JP2003307901A - Color image forming apparatus and control method thereof - Google Patents

Abstract

(57) Abstract: A color image forming apparatus capable of changing a start condition of a color misregistration correction process according to a print mode and performing optimal color misregistration correction, and a control method thereof. When a print mode is designated by a print mode designation section, an image forming section forms an image for each color on a predetermined medium in the designated print mode.
Here, when the new print mode is designated, the color shift of the image formed on the medium is corrected by the color shift correcting unit 242. For this correction, the color misregistration correction information storage unit 23
The combination before and after the change of the print mode and the color shift correction information at the time of each combination are used.
That is, when the color misregistration detecting unit 241 detects color misregistration of an image formed in a plurality of colors on a medium, the color misregistration correction unit 2
42 corrects the color shift of the image using the corresponding color shift correction information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus having a color shift correcting means and a control method thereof.

[0002]

2. Description of the Related Art An example of a conventional image forming apparatus will be described with reference to the drawings. 10, FIG. 11 and FIG. 12 are diagrams each showing the configuration of a conventional tandem type image forming apparatus.

First, an image forming operation of a conventional laser beam printer will be described based on the image forming apparatus shown in FIGS. 10, 11 and 12. Generally, in a tandem type image forming apparatus, an image forming unit is provided for each color of a black image (Bk), a yellow image (Y), a magenta image (M) and a cyan image (C). Then, in each of the image forming portions, the photosensitive drums 18a to 18d,
Primary chargers 16a to 16 for uniformly charging the photosensitive drum
d, scanner units 11a to 11d that form a latent image on the photosensitive drum, a developing device 1 that develops the latent image into a visible image
4a to 14d, a transfer device 19a for transferring a visible image onto a transfer paper
.About.19d, cleaning devices 15a to 15d for removing the residual toner on the photoconductor, and the like.

When an image forming instruction is input from an external device such as a personal computer (not shown) to the conventional image forming apparatus having such a structure, an image is formed in a controller (not shown) in the image forming apparatus. Information is an image signal (V
DD signal) 101.

The image signal (VDD signal) 101 is input to the laser unit 102 in the scanner unit 11 (11a to 11d). In FIG. 11, reference numeral 103 is
4 shows a laser beam that is on / off modulated by the laser unit 102. Further, the scanner motor 104 causes the rotary polygon mirror (polygon mirror) 105 to steadily rotate. Further, the imaging lens 106 focuses the laser beam 107 changed by the polygon mirror 105 onto the photosensitive drum 18 (18a to 18d) which is the surface to be scanned.

As a result, the laser beam 13 (13a to 13d) modulated by the image signal 101 is horizontally scanned (scanned in the main scanning direction) on the photosensitive drum 18,
A latent image is formed on the photosensitive drum 18.

The beam detecting port 109 is a slit-shaped entrance for taking in a laser beam. The laser beam entering from this entrance is guided to the photoelectric conversion element 111 through the inside of the optical fiber 110. Photoelectric conversion element 111
The laser beam converted into an electric signal by the amplifier is amplified by an amplifier circuit (not shown) and becomes a horizontal synchronizing signal.

On the other hand, in FIG. 10, reference numeral 29 indicates a transfer sheet as a transfer material, which is fed from the cassette 22. The fed transfer paper stands by at the registration rollers 21 in order to keep timing with the image forming unit.

Further, in the vicinity of the registration roller 21, a registration sensor 24 for detecting the leading end of the fed transfer paper.
Is provided. The image forming control unit that controls the image forming unit detects the timing when the leading edge of the paper reaches the registration roller 21 based on the detection result of the registration sensor 24, and detects the first color (cyan color in the example of the image forming apparatus shown in FIG. 10). Image is formed on the photosensitive drum 18d, which is an image carrier, and the heater temperature (not shown) in the fixing device 23 is controlled to a predetermined temperature.

Reference numeral 29 indicates a suction roller. A suction bias is applied to the shaft of this roller to electrostatically attract the transfer paper onto the conveyor belt 20. The transfer sheet waiting by the registration roller 21 is conveyed on the transfer belt 20 arranged so as to pass through the image forming units of respective colors at the timing of the detection result of the registration sensor 24 and the image forming process, and at the same time, the transfer device. The image of the first color is transferred onto the transfer paper by 19d.

Similarly, the image of the second color (magenta in the example of the image forming apparatus shown in FIG. 10) is transferred onto the transfer belt 20 at the timing of the detection result of the registration sensor 24 and the second color image forming process. The transferred image is superimposed and transferred onto the image of the first color on the transfer paper. Similarly, the third color (Fig.
The image of the yellow color in the example of the image forming apparatus shown in 0) and the image of the fourth color (black in the example of the image forming apparatus shown in FIG. 10) are
The images are sequentially transferred and superposed on the transfer paper in synchronization with each image forming process.

The transfer paper on which the four color toner images have been transferred is melted and fixed by a fixing device 23 having a halogen heater incorporated therein, and is discharged to the outside of the machine.

Next, a color misregistration correction method in a conventional image forming apparatus will be described with reference to FIGS.

As a problem of the conventional image forming apparatus having a plurality of image forming portions, there is
When the unevenness of movement of multiple photosensitive drums or conveyor belts, the relationship between the outer peripheral surface of the photosensitive drums at the transfer position of each image forming unit and the amount of movement of the conveyor belt, etc. It is possible that the colors do not match and a color shift occurs. In addition, changes over time of the photosensitive drum and the conveyor belt, fatigue, humidity and temperature in the apparatus, etc. may cause color misregistration.

In particular, in a conventional image forming apparatus having a plurality of image forming units having a laser scanner and a photosensitive drum,
There is an error in the distance between the laser scanner and the photosensitive drum in each image forming unit. If this error differs between each image forming unit, a difference occurs in the scanning width of the laser on the photosensitive drum, causing color misregistration. .

FIG. 13 is a diagram showing an example of color shift that occurs in a conventional image forming apparatus. In FIG. 13, reference numeral 20
Reference numeral 7 denotes an original image position, and reference numerals 208a to 208d denote image positions when color misregistration occurs. Further, in the same drawing, (a), (b), and (c) are transfer examples in the case where there is a color shift in the main scanning direction. Incidentally, FIG.
In (c), two lines are drawn apart in the transport direction for easy understanding.

In FIG. 13, (a) shows an example of transfer in the case where there is a tilt deviation of the main scanning line, which occurs when there is a tilt between the optical section and the photosensitive drum. For example, by adjusting the positions of the optical unit and the photosensitive drum and the position of the lens, the correction is performed in the arrow direction.

Further, (b) shows an example of transfer in the case where there is a color shift due to variation in the main scanning line width, which occurs due to a difference in distance between the optical section (laser) and the photosensitive drum. This is likely to occur when the optical unit is a laser scanner. For example, fine-tune the image frequency (if the scan width is too long,
Increase the frequency. ), And the direction of the arrow is corrected by changing the length of the scanning line.

(C) shows a writing position error in the main scanning direction. For example, when the optical unit is a laser scanner as in the present embodiment, the writing timing from the beam detection position is adjusted to make correction in the arrow direction.

Further, (d) shows a writing position error in the sheet conveying direction. For example, the writing timing of each color from the detection of the leading edge of the sheet is adjusted to correct the arrow direction.

As one of the means for correcting these color misregistrations, in the conventional image forming apparatus, the cumulative total of the number of printed sheets is counted, and the color misregistration correction judgment showing the degree of temporal change of each part which is the factor of color misregistration is determined. Seeking a value. When the obtained color misregistration correction determination value is equal to or greater than the predetermined value, the following color misregistration detection is performed, and the various adjustments described above are performed according to the detected misregistration amount.

To detect the color misregistration, a pattern for detecting the color misregistration is formed for each color on the conveyor belt 20 shown in FIG. 10, and a pair of optical sensors provided on both sides of the downstream side of the conveyor belt are used. Used.

FIG. 14 is a diagram showing an example of a color shift detection pattern. In FIG. 14, reference numerals 209a to 209d
Reference numerals 210a to 210d indicate patterns for detecting the amount of color misregistration in the paper transport direction (sub-scanning direction). Further, reference numerals 211a to 211d and reference numerals 212a to 212.
Reference character d denotes a pattern for detecting the amount of color misregistration in the main scanning direction orthogonal to the paper transport direction, and has a tilt of 45 degrees in FIG. In the reference numerals 209 to 212, a
To d represent black (Bk), yellow (Y), magenta (M) and cyan (C), respectively.

Further, in FIG. 14, reference characters tsf1 to t
sf4, tmf1 to tmf4, tsr1 to tsr4 and tmr1 to tmr4 indicate the detection timing of each pattern. Further, the arrow indicates the moving direction of the conveyor belt 20.

Here, the moving speed of the conveyor belt 20 is set to vm.
m / s, black is the reference color, the theoretical distance between each color of the paper transport direction pattern and the black pattern is dsYmm, dsMmm, d
sCmm. At this time, the positional deviation amount δes of each color in the transport direction is δesY = v * {(tsf2-tsf1) + (tsr2-tsr1)} / 2-dsY (1) δesM = when black (Bk) is used as the reference color. v * {(tsf3-tsf1) + (tsr3-tsr1)} / 2-dsM (2) deltaesC = v * {(tsf4-tsf1) + (tsr4-tsr1)} / 2-dsC (3).

On the other hand, the measured distance between the pattern for the sheet conveyance direction of each color and the pattern for the main scanning direction is set to dm
fBkmm, dmfYmm, dmfMmm, dmfCm
m, dmrBkmm, dmrYmm, dmrMmm, d
If mrCmm, then dmfBk = v * (tmf1-tsf1) (4) dmfY = v * (tmf2-tsf2) (5) dmfM = v * (tmf3-tsf3) (6) dmfC = v * (tmf4-tsf4) ( 7) dmrBk = v * (tmr1-tsr1) (8) dmrY = v * (tmr2-tsr2) (9) dmrM = v * (tmr3-tsr3) (10) dmrC = v * (tmr4-tsr4) (11) Is.

Therefore, the positional shift amounts δemf and δemr of the respective colors in the main scanning direction are as follows: dmrBk (15) δemrM = dmrM-dmrBk (16) δemrC = dmrC-dmrBk (17), and it is possible to determine the deviation direction from the positive or negative of the calculation result. Then, the writing position is changed from δemf to δemr
The main scanning width is corrected from −δemf. If there is an error in the main scanning width, the writing position is calculated not only by δemf but also by taking into account the amount of change in the image frequency that has changed due to the main scanning width correction.

FIG. 15 is a diagram for explaining the detecting operation of the color shift detecting means in the conventional image forming apparatus. Figure 15
In the figure, reference numeral 251 denotes a light emitting element, which is realized by, for example, an LED. Reference numeral 252 indicates a light receiving element, which is, for example, a photo sensor. Further, reference numeral 20 indicates a conveyor belt. Furthermore, reference numerals 209, 210 and 2
Reference numerals 11 and 212 denote patterns for detecting color shift.

Further, reference numeral 253 is a light emitting element 25.
The reference numeral 254 indicates the light emitted from the reference numeral 1, and the reference numeral 254 indicates the conveyor belt 20 or the color shift detection patterns 209, 210, and 2.
Of the reflected light from 11 and 213, the received light received by the light receiving element 252 is shown. That is, the light emitting unit and the light receiving unit in the color misregistration detection unit are configured by a regular reflection optical system having the conveyor belt 20 as a reflection surface, and the conveyor belt 20.
The position of the color misregistration detection pattern can be detected by the difference in the reflectance of the specular reflection light of the color misregistration detection pattern, that is, the difference in the reflectance.

FIG. 16 is a block diagram showing the structure of a pattern reading processing unit in a conventional image forming apparatus.
As shown in FIG. 16, a conventional pattern reading processing unit includes a pattern detection unit 1101 including an LED light emitting unit and a photo sensor light receiving unit, and a calculation unit that calculates detection data and calculates a color shift amount and a correction value. 1102, an image output unit 1103 that forms an image according to a calculation result, and timers 1104 and C that perform timing adjustment and various settings of each unit.
PU1105 is made into a component.

FIG. 17 is a block diagram showing a circuit configuration of a light receiving portion in the conventional color shift detecting means shown in FIG. In FIG. 17, the detection current output from the light receiving element 252 is converted into a voltage by the I / V conversion circuit 121. Then, the maximum value and the minimum value of the voltage are detected by the upper peak hold circuit 122 and the lower peak hold circuit 123, respectively, and divided by the resistors 124 and 125. Further, based on the output waveform of the I / V conversion circuit 121 and the voltage value divided by the resistors 124 and 125, the comparison circuit 126 compares the magnitude relationship between them and generates a pulse signal (position information pulse). To be done.

Further, it has a function of resetting the information held in the upper peak hold circuit 122 and the lower peak hold circuit 123 which operate based on the reset signal from the CPU 1105. Here, in order for the upper peak hold circuit 122 and the lower peak hold circuit 123 to respectively obtain the maximum value and the minimum value of the voltage, it is necessary to read at least one line in advance. Then, the pulse conversion reference voltage is created from the maximum value and the minimum value of the voltage acquired here. That is, immediately before the detection of the color shift detection patterns 209a to 209d shown in FIG. 14, it is necessary to create the color shift detection patterns 213 and 214 for acquiring the maximum value and the minimum value of the voltage.

FIG. 18 is a diagram for explaining a detection waveform when a color shift detection pattern is detected by the conventional color shift detection means shown in FIG. In the graph shown in FIG. 18, the horizontal axis represents time t. Also, (a)
Are color shift patterns 209 and 2 detected by the light receiving element 252.
It shows 10, 211 and 212. Furthermore, (b)
Indicates a maximum value, (c) indicates a reference threshold value of the comparison circuit generated from the output of the minimum value detection circuit, and (d) indicates an output (position information pulse) of the detection circuit.

In FIG. 15, when the reflectance of the conveyor belt 20 is high, most of the emitted light 253 becomes specular reflected light 254 and is received by the light receiving element 252. In addition, the color misregistration detection pattern that is a toner image has a low reflectance, most of the emitted light 253 is scattered, and the specularly reflected light 254 received by the light receiving element 252 is small. Therefore, the output waveform (b) is high when the conveyor belt 20 is detected,
It becomes low when detecting the color shift detection pattern.

On the other hand, the threshold value (c) is the resistance 124,
It is determined by the partial pressure ratio of 125. This relationship is represented by A: B = resistor 124: resistor 125 (18).

As shown in FIG. 14, color misregistration detection patterns 209a to 209d and reference numeral 210 are formed on the conveyor belt 20.
a to 210d are formed, and the color misregistration detection sensors 206a and 2d are formed.
It is detected by 06b. As a result, the light receiving element 25
2 outputs four waveforms corresponding to FIG. That is, the first corresponds to the black color shift detection pattern, the second corresponds to the yellow color shift detection pattern, the third corresponds to the magenta color shift detection pattern, and the fourth corresponds to the cyan color shift detection pattern. At this time, the waveforms for detecting the patterns of the four colors show the same shape. Also, first to
The fourth valley is below the threshold (c) and
A pulse corresponding to (d) in is output from the comparison circuit 126.

Further, the arithmetic unit 1102 shown in FIG. 16 obtains the center positions of the first to fourth pulses shown in FIG. 18D, and further obtains the time difference between the respective center positions. Then, the color misregistration amount is calculated from the difference between the obtained time difference and the preset time difference.

[0038]

However, the conventional image forming apparatus has the following problems. That is, in the conventional image forming apparatus, the cumulative number of printed sheets is counted to obtain the color misregistration correction determination value that indicates the degree of fatigue and the degree of fatigue of each part that is the cause of color misregistration. When the color misregistration correction determination value is equal to or greater than the predetermined value, color misregistration is detected, and various adjustments are performed according to the detected misregistration amount. However, in the case of such an image forming apparatus, the color misregistration correction is not always performed under the optimum condition according to the print mode.

For example, in the monochrome print mode using only black toner, the other yellow, magenta, and cyan colors are not printed, so even if the positional accuracy of the black toner is slightly shifted, the print quality is not a big problem. That is, in the monochrome print mode, since the color misregistration correction processing time only takes time and the print quality does not matter, it is better not to perform the color misregistration correction processing even when the color misregistration correction determination value is equal to or more than a predetermined value. desirable.

On the other hand, when printing on more expensive paper than ordinary paper such as color-only paper or postcards, or when the high-quality printing mode is selected even for plain paper, the user will see color misregistration. It is considered that the expectation is high image quality in which the above are corrected.
In such a case, it is desirable to perform the color misregistration correction process before starting printing.

However, conventionally, since the color misregistration correction processing is executed when the color misregistration correction judgment value is equal to or larger than a predetermined threshold value, if the color misregistration correction judgment value is equal to or larger than the predetermined value, the monochrome mode is set. Even in this case, the color misregistration correction is executed, which causes a problem that an unnecessary waiting time occurs for the user.

Even if the user desires a high image quality with the color shift corrected, if the color shift correction judgment value is equal to or less than a predetermined value, the color shift correction processing is performed to cause each part that is a cause of the color shift. Since the change over time and the degree of fatigue are large, it is not always possible to provide image quality that meets the expectations of the user. In other words, because the optimum color misregistration correction could not be performed according to the print mode,
It is desired to improve this.

The present invention has been made in consideration of such circumstances, and the starting condition of the color misregistration correction processing can be changed according to the print mode, and the optimum color misregistration correction can be performed. An object is to provide a color image forming apparatus and a control method thereof.

[0044]

In order to solve the above problems, the present invention provides a print mode designating means for designating a print mode and an image for each color on a predetermined medium in the designated print mode. A plurality of image forming units to be formed, a color shift detecting unit to detect a color shift of an image formed in a plurality of colors on the medium, and a new print mode is formed on the medium. A color image forming apparatus comprising: a color shift correction unit that corrects a color shift of an image,
A color misregistration correction information storage unit that stores the combination before and after the change of the print mode and the color misregistration correction information at each combination is provided, and the color misregistration correction unit is based on the combination before and after the change of the print mode. Is used to correct the color shift of the image formed on the medium.

Further, in the color image forming apparatus according to the present invention, the image forming means is formed on the image carrier and a toner image forming means for forming a toner image on the image carrier in a designated print mode. It is characterized by comprising a transfer means for transferring the toner image onto a predetermined medium, and a conveying means for conveying the medium to the image carrier.

Further, in the color image forming apparatus according to the present invention, the color misregistration correction unit determines whether or not the color misregistration correction process is necessary according to the combination of the print mode before the change and the print mode after the change. Is characterized by.

Furthermore, in the color image forming apparatus according to the present invention, the print mode can be designated from a plurality of image quality modes, and the changed print mode has a lower image quality than the print mode before the change. In the print mode, the color misregistration correction information is information that does not correct the color misregistration of the image.

Furthermore, in the color image forming apparatus according to the present invention, the print mode is a mode that can be designated from a plurality of image quality modes, and the color misregistration correction unit has the changed print mode before the change. In the case of a print mode having a higher image quality than the print mode, the color misregistration of the image is corrected.

Furthermore, in the color image forming apparatus according to the present invention, the color misregistration correction means has a color misregistration correction judgment value indicating a degree of progress of fatigue or secular change of each part of the color image forming apparatus to be a threshold value or more. In this case, the color shift of the image is corrected.

Furthermore, the color image forming apparatus according to the present invention comprises threshold value storage means for storing the threshold value,
It further comprises threshold changing means for changing the threshold to a threshold according to the changed print mode when the print mode is changed.

Furthermore, in the color image forming apparatus according to the present invention, the color misregistration correction means sets the color misregistration correction judgment value indicating the degree of progress of fatigue or aging of each part of the color image forming apparatus. Corrected based on the detection result of the temperature detection means or the humidity detection means provided inside,
If the color misregistration correction judgment value after correction exceeds the specified value,
It is characterized in that the color shift of the image is corrected.

Further, according to the present invention, print mode designating means for designating a print mode, and a plurality of image forming means for forming toner images of different colors on a plurality of image carriers, respectively.
A transfer unit that superimposes the toner images of different colors on each other and transfers it to an intermediate transfer member, a color shift detection unit that detects a color shift of an image formed by a plurality of colors on the intermediate transfer member, and a new printing mode. Is specified, the color image forming apparatus is provided with a color misregistration correction unit that corrects color misregistration of an image formed on the intermediate transfer member. A color misregistration correction information storage unit that stores color misregistration correction information is further provided, and the color misregistration correction unit is formed on the intermediate transfer member by using the color misregistration correction information based on the combination before and after the change of the print mode. It is characterized in that color shift of an image is corrected.

[0053]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of a color image forming apparatus of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 shows a first embodiment of the present invention.
6 is a flowchart for explaining an operation procedure of the color image forming apparatus according to the embodiment. Regarding the configuration of the tandem type laser printer, which is an example of the color image forming apparatus according to the present embodiment, the image forming operation, and the color misregistration correction process, when the print mode is changed, depending on the combination of the modes before and after the change. The part that executes the color misregistration correction process is different, and the other parts are the same as those of the conventional image forming apparatus described above.

FIG. 2 is a block diagram showing the arrangement of the color image forming apparatus according to the first embodiment of the present invention. Figure 2
As shown in FIG. 3, the color image forming apparatus according to the present embodiment includes a print mode designating section 21 for designating a print mode, an image forming section 22 for forming an image, a storage section 23, and an image forming control section 24 for controlling them. Composed of and.

The image forming control unit 24 for controlling the image formation of the color image forming apparatus has a result selected by the user from an external device such as a personal computer, or various kinds such as a paper type sensor provided in the color image forming apparatus. As the detection result of the sensor or the like, print information such as color printing / monochrome printing, single-sided printing / double-sided printing, special paper printing / plain paper printing, or the like is input as information from the print mode specifying unit 21. And
The image formation control unit 24, based on these print information,
The image forming unit 23 is made to form an image in a predetermined print mode.

That is, when a print job is started (step S101), the image forming control section 24 confirms whether the print mode has been changed from the previous print job (step S102). As a result, when the print mode is changed (YES), it is determined whether the combination of the modes before and after the change is a combination that requires color misregistration correction (step S107).

The determination method performed in step S107 will be described. A case where the image forming mode of the image forming apparatus has, for example, three modes of high image quality / special paper mode, color mode, and monochrome mode will be described. In addition, the order of image quality requested by the user for color misregistration is (1) high image quality / special paper mode, (2) color mode, and (3) monochrome mode in the order of high image quality. , Special paper is color special paper.

For example, the high image quality of the color before the mode change
If the special paper mode is the normal color mode after the mode change, the user is not asking for the high image quality but the normal image quality after the mode change. Therefore, it is not necessary to perform the color misregistration correction process at the timing of changing this mode. This is because the image quality is improved and the user waiting time is increased when the correction process is performed.

On the contrary, when the normal color mode is used before the mode change and the high image quality / special paper mode is used after the mode change, the user desires high image quality after the mode change, and thus the color misregistration correction is performed. It needs to be processed. That is, when the mode is switched from high image quality to normal image quality, color shift correction is not performed. On the other hand, when the mode is switched from the normal image quality to the high image quality, the color misregistration correction suitable for the selected mode can be performed by performing the color misregistration correction.

FIG. 3 is a diagram summarizing the necessity of color misregistration correction when changing modes in the color image forming apparatus according to the present embodiment. In FIG. 3, a circle mark indicates that color misregistration correction is performed, and a cross mark indicates that color misregistration correction is not performed.

If the result of determination in step S107 is that the mode requires color misregistration correction (YE
S), and color misregistration correction is executed (step S105). Then, the color misregistration correction determination value, which is a reference for executing the color misregistration correction processing, is cleared (step S106). Here, the color misregistration correction determination value is the EE provided in the color image forming apparatus.
It is stored in the storage unit 23 such as a PROM. The image formation control unit 24 reads and writes the color misregistration correction determination value.

On the other hand, in step S102, if the print mode is not changed (NO), a predetermined formula or the like is used based on the change over time and the degree of fatigue due to the number of printed sheets, the number of rotations of the photosensitive drum, and the like. A color misregistration correction determination value is obtained (step S103). Next, it is determined whether the color misregistration correction determination value is greater than or equal to a predetermined threshold Th (step S104). As a result, if the color misregistration correction determination value is equal to or larger than the threshold Th (YES), step S105.
In step S106, the color misregistration correction process is performed, and in step S106, the color misregistration correction determination value serving as a reference for performing the color misregistration correction process is cleared and stored in the storage unit. On the other hand, when the color misregistration correction determination value is less than the threshold Th (NO), the color misregistration correction determination value is stored as it is.

As described above, even when the print mode is changed, the color shift correction processing is performed according to the combination of the modes before and after the change, so that the color shift processing suitable for the print mode can be performed. it can.

In order to enable the above-described operation, the image formation control section 24 includes the color shift detection section 241 and the color shift correction section 2.
Function as 42. The storage unit 23 also functions as the color misregistration correction information storage unit 231.

That is, according to the present invention, a print mode designating means (print mode designating section 21) for designating a print mode and a plurality of images for forming an image for each color on a predetermined medium in the designated print mode. Forming means (image forming section 2
2), a color shift detection unit (color shift detection unit 241) that detects the color shift of an image formed in a plurality of colors on the medium, and a new print mode is formed on the medium. A color image forming apparatus including a color shift correction unit (color shift correction unit 242) that corrects a color shift of an image, in which colors before and after changing a print mode and color shift correction information at the time of each combination are stored. A misregistration correction information storage unit (color misregistration correction information storage unit 231) is further provided, and the color misregistration correction unit (color misregistration correction unit 242) uses the color misregistration correction information based on the combination before and after the change of the print mode on the medium. It is characterized in that the color misregistration of the image formed on the image is corrected.

The image forming section 22 further includes a toner image forming section 221, a transfer section 222, and a conveying section 223. Therefore, in the color image forming apparatus according to the present invention, the image forming unit (image forming unit 22) and the toner image forming unit (toner image forming unit 221) form the toner image on the image carrier in the designated print mode. , Transfer means (transfer section 222) for transferring the toner image formed on the image carrier onto a predetermined medium
And a transport unit (transport unit 22) for transporting the medium to the image carrier.
3) and are provided.

Further, in the color image forming apparatus according to the present invention, the color misregistration correction means (color misregistration correction unit 242) performs the color misregistration correction processing according to the combination of the print mode before the change and the print mode after the change. The feature is that the necessity is determined. Furthermore, in the color image forming apparatus according to the present invention, when the print mode is a mode that can be designated from a plurality of image quality modes and the changed print mode is a print mode having a lower image quality than the print mode before the change, The color misregistration correction information is information that does not correct the color misregistration of the image.

In this embodiment, color special paper is taken as an example of the special paper, and in order to simplify the description,
The special paper mode and the high image quality mode designated by the user are explained as the same mode. Here, the special paper includes paper types such as special color paper, postcards, thick paper, and thin paper. Therefore, when there are a plurality of print modes for each paper type, the mode is set according to the mode. The same can be achieved by deciding in advance whether or not the color misregistration correction process should be executed at the time of change.

<Second Embodiment> FIG. 4 shows a second embodiment of the present invention.
6 is a flowchart for explaining an operation procedure of the color image forming apparatus according to the exemplary embodiment. The configuration, image forming operation, and color misregistration correction processing of the tandem type laser printer, which is an example of the color image forming apparatus of the present embodiment, are the same as those used in the first embodiment. In this embodiment, a color image forming apparatus will be described in which, when the print mode is changed, the threshold value of the color misregistration correction determination value is changed according to the changed mode.

FIG. 5 is a block diagram showing the arrangement of a color image forming apparatus according to the second embodiment of the present invention. Similarly to the color image forming apparatus according to the first embodiment, the color image forming apparatus according to the present embodiment also has a print mode specifying unit 51 that specifies a print mode and an image forming unit 5 that forms an image.
2, a storage unit 53, and an image formation control unit 54 that controls them.

The image formation control section 54 for controlling the image formation of the color image forming apparatus has a result selected by the user from an external device such as a personal computer, or various types such as a paper type sensor provided in the color image forming apparatus. Color print / monochrome print, single-sided print /
Print information such as double-sided printing, special paper printing / plain paper printing, etc. is input. Then, the image forming control unit causes the image forming unit to form an image in a predetermined print mode based on the print information.

First, when a print job is started (step S201), the image formation control unit 54 confirms whether the print mode has been changed from the previous print job (step S202). As a result, when the print mode has been changed (YES), the threshold value of the color misregistration correction determination value corresponding to the mode before and after the change is changed (step S207).

Here, the threshold value of the color misregistration correction determination value corresponding to the mode will be described. It is assumed that the color image forming apparatus has three image forming modes, for example, a high image quality / special paper mode, a color mode, and a monochrome mode. At this time, it is considered that the order of image quality requested by the user for the color shift is (1) high image quality / special paper mode, (2) color mode, and (3) monochrome mode in order of high image quality. In the present embodiment, as an example, the special paper is color special paper.

For example, the high image quality of color before the mode change
In the special paper mode, when the changed color mode is the normal color mode, it means that the user wants not the high image quality but the normal image quality after the mode change. Therefore, the color misregistration correction process in the normal color mode does not need to be performed more frequently than in the high image quality / special paper mode. This is because if the correction process is performed frequently, the image quality is improved but the waiting time for the user is increased.

On the contrary, when the normal color mode is before the mode change and the high image quality / special paper mode is after the mode change,
Since the user desires high image quality after changing the mode, it is necessary to increase the frequency of color misregistration correction processing to maintain high image quality after changing the mode. That is, in the high image quality mode, the frequency of color misregistration correction is increased by lowering the threshold value of the color misregistration correction determination value. Further, in the normal image quality mode, in order to reduce the waiting time of the user as much as possible, it is desirable to reduce the number of color misregistration corrections by raising the threshold value as compared with the high image quality mode.

FIG. 6 is a diagram showing the color misregistration correction determination threshold value according to the print mode in the color image forming apparatus according to the second embodiment. In this embodiment, the threshold values (Th1 <Th2 <Th3) shown in FIG. 6 are used.

In monochrome printing, color misregistration correction is generally unnecessary. Therefore, by setting the threshold value in the monochrome mode to a value that is not possible when the color misregistration determination value is normally obtained, color misregistration correction is not performed in the monochrome mode, and the user wait time due to the color misregistration correction processing is not performed. There is no increase in However, since a color image forming apparatus generally has many printing modes, the size relationship of Th1 to Th3 as shown in FIG. 6 does not always hold.

Next, the color misregistration correction judgment value is obtained from a predetermined calculation formula or the like based on the time-dependent change and the degree of fatigue due to the number of printed sheets, the number of rotations of the photosensitive drum, etc. (step S
208). Then, it is determined whether or not the color misregistration correction determination value exceeds a threshold Th1 (in this embodiment, high image quality / special paper mode) corresponding to a predetermined print mode (step S).
209).

As a result, if the threshold value Th1 is exceeded (YES), color misregistration correction processing is performed (step S20).
5). Then, the color misregistration correction determination value, which is a reference for executing the color misregistration correction processing, is cleared (step S206). This color misregistration correction judgment value is the E value provided in the color image forming apparatus.
The image forming control unit stores the color misregistration correction determination value stored in a storage unit such as an EPROM.

On the other hand, if the print mode has not been changed in step S202 (NO), the color misregistration correction determination value is similarly obtained (step S203). After that, it is determined whether or not the color misregistration correction determination value exceeds a predetermined threshold Th according to the print mode from the previous time (step S20).
4). As a result, when the threshold value Th is exceeded (YE
S), the color misregistration correction process is performed (step S20).
5). Then, the color misregistration correction determination value, which is a reference for executing the color misregistration correction process, is cleared and stored in the storage unit (step S
206). On the other hand, in step S204, if the threshold value Th is not satisfied (NO), the color misregistration correction determination value is stored as it is.

As described above, when the print mode is changed, the color shift correction processing suitable for the print mode is performed by changing the threshold value of the color shift correction judgment value according to the changed mode. be able to.

Further, in the present embodiment, the special color paper is taken as an example of the special paper, and the special paper mode and the high image quality mode designated by the user are treated as the same mode in order to simplify the description. did. The special papers include color special papers, postcards, thick papers, thin papers, and the like. Therefore, when there are a plurality of print modes for each paper type, it is necessary to determine the threshold value of the color misregistration correction determination value in advance according to those modes.

Further, when the color image forming section 52 is provided with the temperature sensor 521 or the humidity sensor 521, the color misregistration correction judgment value is determined according to the combination of the print mode and the temperature or humidity in the color image forming apparatus. If the threshold value is determined in advance, it is possible to more appropriately correct the color misregistration caused by the change over time and the degree of fatigue of each part due to temperature and humidity.

Further, in the case of a combination that requires color misregistration correction by combination with the first embodiment or by combination with modes before and after the change, the threshold value of the color misregistration correction judgment value is changed. Needless to say, is also effective.

That is, in the color image forming apparatus according to the present invention, the color misregistration correction means (color misregistration correction section 542) has a predetermined color misregistration correction judgment value indicating the degree of progress of fatigue or secular change of each part of the color image forming apparatus. When the value is equal to or more than the value, it is characterized in that the color shift of the image is corrected. Further, the color image forming apparatus according to the present invention includes a threshold value storage unit (threshold value storage unit 531) for storing a threshold value, and a print mode after the threshold value is changed in accordance with a change in the print mode. And a threshold value changing unit (threshold value changing unit 541) for changing the threshold value according to the above.

Further, in the color image forming apparatus according to the present invention, the color misregistration correction means (color misregistration correction section 542) sets the color misregistration correction judgment value indicating the degree of progress of fatigue or secular change of each part of the color image forming apparatus, Correction is performed based on the detection result of the temperature detecting unit (temperature sensor 521) or the humidity detecting unit (humidity sensor 522) provided inside the color image forming apparatus, and the corrected color misregistration correction determination value becomes a predetermined value or more. In this case, the color shift of the image is corrected.

<Third Embodiment> Next, a color image forming apparatus according to a third embodiment will be described. The configuration of the tandem type laser printer, which is an example of the color image forming apparatus of the present embodiment, the image forming operation, and the color misregistration correction process are the same as those of the color image forming apparatuses of the first and second embodiments. In the present embodiment, when the print mode is changed, the correction coefficient of the color misregistration correction judgment value is changed according to the changed mode.

FIG. 7 is a flow chart for explaining the operation procedure of the color image forming apparatus according to the third embodiment. The configuration of the color image forming apparatus according to this embodiment is the same as that of the color image forming apparatus according to the second embodiment. The image forming control unit for controlling the image forming of the color image forming apparatus detects a result selected by a user from an external device such as a personal computer or various sensors such as a paper type sensor provided in the color image forming apparatus. From the results, color printing / monochrome printing, simplex printing / duplex printing,
Print information such as special paper printing / plain paper printing is input. Then, the image forming control unit causes the image forming unit to form an image in a predetermined print mode based on the print information.

First, when a print job is started (step S301), the image formation control unit confirms whether the print mode has been changed from the previous print job (step S302). As a result, when the print mode is changed (YES), the correction coefficient is changed to the color misregistration correction determination value corresponding to the mode before and after the change (step S).
307).

Here, the correction coefficient of the color misregistration correction judgment value corresponding to the mode will be described. High-quality / special paper mode, color (single-sided) mode, color (double-sided) in a color image-forming apparatus having a double-sided printing function or a color image-forming apparatus capable of double-sided printing by mounting an optional double-sided unit. Mode, monochrome (single sided)
When there are five image forming modes, i.e., a mode and a monochrome (double-sided) mode, the changes over time and the degree of fatigue of each part that cause color misregistration are usually different for each mode. Therefore, it is necessary to correct the color misregistration correction determination value according to each print mode.

For example, when the total number of printed sheets is counted and the color misregistration correction judgment value is obtained as in the conventional image forming apparatus, inconvenience occurs in single-sided printing and double-sided printing. When the number of printed sheets is 1, for single-sided printing,
In double-sided printing, image formation is performed twice on the front and back of paper.
For this reason, it can be said that even with the same printing of one sheet, double-sided printing has a greater degree of change over time and the degree of fatigue of each part, which is a factor of color misregistration, than single-sided printing.

Further, in an image forming apparatus capable of double-sided printing, generally, the paper after printing on the front surface is once returned to the inside of the apparatus and re-fed to perform back surface printing. At this time, the temperature inside the apparatus often rises and the humidity lowers due to the paper warmed by the fixing device at the time of front side printing, as compared with the case of single sided printing. Therefore, it can be said that the double-sided printing is larger than the single-sided printing in the time-dependent change and the degree of fatigue of each part, which is a factor of color misregistration due to the temperature rise in the apparatus. Further, in the special paper mode such as the thick paper, it is general to change the image forming conditions such as the paper transport speed and the adjusting temperature of the fixing device, as compared with the plain paper mode. Therefore, even with the same printing of one sheet, the changes over time and the degree of fatigue of each portion that cause color misregistration differ depending on the type of paper to be printed (print mode).

In order to perform the color misregistration correction process under appropriate conditions according to the temporal change and the degree of fatigue of each part which causes the color misregistration due to the difference in the print mode, the color misregistration correction judgment value is obtained. In addition, it is necessary to perform the correction using the correction coefficient provided in advance according to the print mode.

FIG. 8 is a diagram showing the correction values of the color misregistration correction determination value according to the print mode according to the third embodiment. In the present embodiment, the correction value as shown in FIG. 8 is used, but the correction coefficient in the double-sided printing mode is set to a value larger than the correction coefficient in the single-sided printing mode for the reason described above.

When obtaining the color misregistration correction judgment value, the number of printed sheets is multiplied by this correction coefficient K3 (step S
303). Then, it is determined whether the color misregistration correction determination value corrected by the correction coefficient K3 exceeds the threshold Th (step S304). As a result, if the color misregistration correction determination value exceeds the threshold Th (YES), color misregistration correction processing is performed (step S305). Further, the color misregistration correction determination value, which is a reference for executing the color misregistration correction processing, is cleared (step S306). The color misregistration correction determination value is stored in a storage unit such as an EEPROM provided in the color image forming apparatus, and the image misregistration correction determination value is read and written by the image forming control unit.

As described above, by performing the correction according to the mode, the color shift correction determination value becomes larger in the double-sided print mode than in the single-sided print mode even with the same number of prints. Will be higher. Therefore, appropriate color misregistration correction can be performed according to the change over time and the degree of fatigue of each part that causes color misregistration.

On the other hand, if the print mode is not changed in step S302 (NO), the color misregistration correction judgment value is obtained by multiplying the correction coefficient according to the print mode from the previous time (step S303). After that, it is determined whether the color misregistration correction determination value exceeds a predetermined threshold Th (step S304). As a result, if the color misregistration correction determination value exceeds the predetermined threshold value (YES), color misregistration correction processing is performed (step S305). Then, the color misregistration correction determination value, which is a reference for executing the color misregistration correction process, is cleared and stored in the storage unit (step S306). On the other hand, when the color misregistration correction determination value is less than the threshold Th (NO), the color misregistration correction determination value is stored as it is.

As described above, when the print mode is changed, the color misregistration correction determination value is corrected according to the changed mode, so that the color misregistration correction process can be performed at a timing suitable for the print mode. . In the present embodiment, the special color paper is taken as an example of the special paper, and the special paper mode and the high image quality mode designated by the user are treated as the same mode in order to simplify the description. here,
Special papers include special color papers, postcards, thick papers, thin papers, and so on.If there are multiple print modes for each paper type, color misregistration correction judgment is performed according to those modes. It is necessary to determine the correction coefficient of the value in advance.

In this embodiment, the number of prints is taken as an example when obtaining the color misregistration correction judgment value. However, the number of rotations of the photosensitive drum, the number of rotations of the conveyor belt, and the application of the high voltage used for image formation are applied. It may be obtained based on the number of times. Further, in the color image forming apparatus in which the developing device and the conveyor belt perform the separating operation with respect to the photoconductor or the like, the color misregistration correction determination value may be obtained based on the number of times of the separating operation.

Further, when a temperature sensor or a humidity sensor is provided in the color image forming apparatus, if the correction coefficient is determined in advance according to the combination of the print mode and the temperature or humidity in the color image forming apparatus, It is possible to more appropriately correct the color misregistration caused by the change with time and fatigue of each part due to temperature and humidity.

Further, in the case of a combination that requires the color misregistration correction based on the combination of the first embodiment and the second embodiment, and the combination of the modes before and after the change, the threshold value of the color misregistration correction determination value and the correction value. Needless to say, it is effective to change the. <Fourth Embodiment> Next,
A color image forming apparatus according to the fourth embodiment of the present invention will be described. The present embodiment is different from the above-described first to third embodiments in the configuration of the color image forming apparatus and the image forming process. Here, since the image forming operation of the laser printer is as described in the conventional example and the first to third embodiments, a part thereof will be omitted.

FIG. 9 is a configuration diagram for explaining the detailed configuration of the color image forming apparatus according to the fourth embodiment. That is, when the image forming control unit that controls the image forming unit receives a print signal from a host computer (not shown), the image of the first color (cyan color in this embodiment) is formed on the photosensitive drum 318a that is an image carrier. Fixer 3 as it starts to form
The heater temperature (not shown) of 23 is controlled to a predetermined temperature.

In FIG. 9, reference numeral 325 is an intermediate transfer belt arranged so as to penetrate through the image forming portions of the respective colors, and when the image of the first color is formed, only the photosensitive drum of the first color hits the intermediate transfer belt 325. Contact. Further, the intermediate transfer belt 325 is rotationally driven along with the rotation of the photoconductor drum 318, and when the primary transfer bias is applied to the primary transfer roller 319, it is formed based on the reference position of the intermediate transfer belt 325. The toner image of the first color is sequentially transferred onto the intermediate transfer belt 325.

Similarly, the image of the second color (magenta color in this embodiment) is brought into contact with the intermediate transfer belt 325 only on the photosensitive drum 318b of the second color, and the image of the second color is detected based on the reference position of the intermediate transfer belt 325. The toner image of the intermediate transfer belt 32
5 is superimposed and transferred onto the first color toner image on 5.

Similarly, for the third color (yellow in this embodiment) image, the third-color photoconductor drum 318c is intermediate, and for the fourth-color (black in this embodiment) image, the fourth-color photoconductor drum 318 is intermediate. The transfer belt 325 comes into contact with the transfer belt 325, and the transfer is sequentially performed on the intermediate transfer belt 325.

Reference numeral 326 is a secondary transfer roller for secondarily transferring the toner image formed on the intermediate transfer belt 325 to a transfer sheet, and at the time of image formation, the intermediate transfer belt 325.
Is retracted to a position separated from. Reference numeral 329 is a transfer paper, which is a transfer material, and is fed from the cassette 322. The fed transfer paper 329 stands by at the registration roller 321 in order to keep timing with the image forming unit.

Further, in the vicinity of the registration roller 321,
Registration sensor 3 for detecting the leading edge of the fed transfer paper
24 are provided. The transfer sheet waiting by the registration roller 321 is re-conveyed at the timing of the detection result of the registration sensor 324 and the image forming process. At this time, the secondary transfer roller 326 comes into contact with the intermediate transfer belt 325,
When the secondary transfer bias is applied to the secondary transfer roller 326, the four color toner images on the intermediate transfer belt 325 are collectively transferred onto the transfer paper.

The transfer paper on which the four color toner images have been transferred is fused and fixed by a fixing device 323 having a halogen heater incorporated therein, and is discharged to the outside of the machine. Even in a tandem type image forming apparatus using such an intermediate transfer belt, color misregistration correction can be performed at an appropriate timing according to the print mode, as in the flow described in the first to third embodiments. It is possible.

That is, according to the present invention, the print mode designating means for designating the print mode, the plurality of image forming means for respectively forming the toner images of different colors on the plurality of image carriers, and the toner images of different colors are superposed. Transfer means for transferring the image to the intermediate transfer body, a color misregistration detection means for detecting the color misregistration of an image formed in a plurality of colors on the intermediate transfer body, and a new print mode, when the intermediate transfer body A color image forming apparatus including a color misregistration correction unit that corrects a color misregistration of an image formed on the image forming apparatus, the color misregistration correction information storing color misregistration correction information before and after a combination of changing print modes. The color misregistration correction means further comprises a storage means,
The color shift correction information based on the combination before and after the change of the print mode is used to correct the color shift of the image formed on the intermediate transfer member.

In the first to fourth embodiments, an example of a laser beam printer using a laser beam as an exposure device has been shown. However, it goes without saying that the same effects as those of the present invention can be obtained even in a printer using an LED as an exposure device.

The object of the present invention is to supply a recording medium (or storage medium) recording a program code of software for realizing the functions of the above-described embodiment to a system or apparatus, and to supply a computer of the system or apparatus ( It is needless to say that it is also achieved by reading and executing the program code stored in the recording medium by the CPU or MPU). In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium recording the program code constitutes the present invention.

Further, by executing the program code read by the computer, not only the functions of the above-described embodiment are realized, but also the operating system (OS) running on the computer based on the instruction of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the recording medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the recording medium, the recording medium stores the program code corresponding to the above-mentioned flowchart.

By having the above-described structure and performing the above-described operation procedure, the color image forming apparatus according to the present invention does not perform color misregistration correction at the time of monochrome printing in which color misregistration correction is generally unnecessary. It is possible to avoid an increase in the waiting time of the user due to the above.

When the high-quality image forming mode is selected, the color misregistration correction is performed before printing, so that the color misregistration accuracy after the color misregistration correction is good for a user who requests high image quality. Images can be provided. Furthermore, by setting the correction coefficient so that the color misregistration correction judgment value is counted more during double-sided printing than during single-sided printing, it is possible to correct the change over time and the degree of fatigue of each part that causes color misregistration depending on the print mode. However, the color misregistration correction process can be performed under appropriate conditions for each mode.

[0118]

As described above, according to the present invention,
The start condition of the color misregistration correction process can be changed according to the print mode, and the optimum color misregistration correction can be performed.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining an operation procedure of a color image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a color image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram summarizing necessity of color misregistration correction when changing modes in the color image forming apparatus according to the present embodiment.

FIG. 4 is a flowchart for explaining an operation procedure of the color image forming apparatus according to the second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a color image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a color misregistration correction determination threshold value according to a print mode in the color image forming apparatus according to the second embodiment.

FIG. 7 is a flowchart illustrating an operation procedure of a color image forming apparatus according to a third embodiment.

FIG. 8 is a diagram showing a correction value of a color misregistration correction determination value according to a print mode according to the third embodiment.

FIG. 9 is a configuration diagram illustrating a detailed configuration of a color image forming apparatus according to a fourth embodiment.

FIG. 10 is a diagram showing a configuration of a conventional tandem type image forming apparatus.

FIG. 11 is a diagram showing a configuration of a conventional tandem type image forming apparatus.

FIG. 12 is a diagram showing a configuration of a conventional tandem type image forming apparatus.

FIG. 13 is a diagram showing an example of color shift that occurs in a conventional image forming apparatus.

FIG. 14 is a diagram showing an example of a color shift detection pattern.

FIG. 15 is a diagram illustrating a detection operation performed by a color shift detection unit in a conventional image forming apparatus.

FIG. 16 is a block diagram showing a configuration of a pattern reading processing unit in a conventional image forming apparatus.

17 is a block diagram showing a circuit configuration of a light receiving section in the conventional color shift detecting means shown in FIG.

FIG. 18 is a diagram for explaining detection waveforms when a color shift detection pattern is detected by the conventional color shift detection means shown in FIG.

[Explanation of symbols]

21, 51 Print mode specification section 22, 52 Image forming unit 23, 53 storage 24, 54 image formation control unit 221 Toner image forming unit 222 Transfer unit 223 Transport section 231 Color Misregistration Correction Information Storage Unit 241 Color shift detector 242 and 542 color misregistration correction unit 521 Temperature sensor 522 Humidity sensor 531 Threshold storage section 541 Threshold change unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/00 384 H04N 1/29 G 5C079 H04N 1/29 1/40 D 1/46 1/46 Z 1 / 60 B41J 3/00 B F term (reference) 2C262 AA24 AB15 EA04 EA14 EA18 GA04 2H027 DA09 DA11 DA14 DA21 DA38 DA44 DA45 DC02 EB06 EC03 EC06 EC07 eC18 EC20 ED04 FA28 FA30 FA35 2H300 EA12 EB02 EB04 EB07 EB12 EC02 EC05 ED02 ED05 EF02 EF03 EF06 EF08 EF13 EG02 EH16 EH34 EH35 EJ09 EK03 FF02 FF08 FF14 FF15 GG02 GG22 GG23 GG24 GG36 GG37 QQ10 QQ25 QQ28 QQ29 QQ32 RD37 BB15 RD15 BB5A15 TT03 5C079 HB03 KA03 MA11 NA03 NA21 PA03

Claims (26)

[Claims] 1. A print mode designating means for designating a print mode, a plurality of image forming means for forming an image for each color on a predetermined medium in the designated print mode, and a plurality of colors on the medium. A color image including a color shift detecting unit that detects a color shift of the image formed in step S1 and a color shift correcting unit that corrects the color shift of the image formed on the medium when a new print mode is designated. The forming apparatus further includes a color misregistration correction information storage unit that stores the combination before and after the change of the print mode and the color misregistration correction information at the time of each combination, and the color misregistration correction unit is a combination before and after the change of the print mode. A color image forming apparatus, which corrects a color shift of an image formed on the medium using color shift correction information based on the above. 2. The image forming unit transfers a toner image forming unit that forms a toner image on an image carrier in a designated print mode, and the toner image formed on the image carrier onto a predetermined medium. The color image forming apparatus according to claim 1, further comprising a transfer unit and a transport unit that transports the medium to the image carrier. 3. The color misregistration correction unit determines whether or not the color misregistration correction process is necessary according to a combination of a print mode before change and a print mode after change.
Or the color image forming apparatus described in 2. 4. When the print mode is a mode that can be designated from a plurality of image quality modes and the changed print mode has a lower image quality than the print mode before the change, the color misregistration correction information is The color image forming apparatus according to any one of claims 1 to 3, wherein the information is information that does not correct color misregistration of the image. 5. The print mode is a mode that can be designated from a plurality of image quality modes, and the color misregistration correction unit is a print mode in which the changed print mode has a higher image quality than the print mode before the change. The color image forming apparatus according to claim 1, wherein the color misregistration of the image is corrected. 6. The color misregistration correction unit corrects the color misregistration of the image when a color misregistration correction determination value indicating a degree of progress of fatigue or aging of each part of the color image forming apparatus is equal to or more than a threshold value. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a color image forming apparatus. 7. A threshold value storage unit for storing the threshold value, and a threshold value changing unit for changing the threshold value to a threshold value according to the changed print mode in accordance with the change of the print mode. The color image forming apparatus according to claim 6, further comprising: 8. The color misregistration correction means uses a color misregistration correction determination value indicating the degree of progress of fatigue or secular change of each part of the color image forming apparatus as temperature detection means or humidity detection provided inside the color image forming apparatus. 3. The color image according to claim 1, wherein the color image is corrected based on the detection result of the means, and when the corrected color misregistration correction determination value is equal to or larger than a predetermined value, the color misregistration of the image is corrected. Forming equipment. 9. A print mode designating unit that designates a print mode, a plurality of image forming units that form toner images of different colors on a plurality of image carriers, and an intermediate transfer by superimposing the toner images of different colors. Transfer means for transferring to the body, color shift detecting means for detecting color shift of an image formed by a plurality of colors on the intermediate transfer body, and when a new print mode is designated, on the intermediate transfer body A color image forming apparatus comprising: a color misregistration correction unit that corrects a color misregistration of an image to be formed, wherein color misregistration correction information storage stores combinations before and after changing a print mode and color misregistration correction information at each combination. The image forming apparatus further includes a unit, and the color misregistration correcting unit corrects the color misregistration of the image formed on the intermediate transfer member by using the color misregistration correction information based on the combination before and after the change of the print mode. And a color image forming apparatus. 10. The color according to claim 9, wherein the color misregistration correction unit determines whether or not the color misregistration correction process is necessary according to a combination of the print mode before the change and the print mode after the change. Image forming apparatus. 11. When the print mode is a mode that can be designated from a plurality of image quality modes, and the print mode after the change has a lower image quality than the print mode before the change,
The color image forming apparatus according to claim 9, wherein the color misregistration correction information is information that does not correct the color misregistration of the image. 12. The print mode is a mode that can be designated from a plurality of image quality modes, and the color misregistration correction unit is a print mode in which the changed print mode has a higher image quality than the print mode before the change. 11. The color shift of the image is corrected.
The color image forming apparatus described in 1. 13. The color misregistration correction unit corrects the color misregistration of the image when a color misregistration correction determination value indicating a degree of progress of fatigue or aging of each part of the color image forming apparatus is equal to or more than a threshold value. The color image forming apparatus according to claim 9, wherein. 14. A threshold value storage unit for storing the threshold value, and a threshold value changing unit for changing the threshold value to a threshold value according to the changed print mode in accordance with the change of the print mode. 14. The color image forming apparatus according to claim 13, further comprising: 15. The color misregistration correction unit uses a color misregistration correction determination value indicating the degree of progress of fatigue or secular change of each part of the color image forming apparatus as a temperature detecting unit or a humidity detecting unit provided inside the color image forming apparatus. 10. The color image forming apparatus according to claim 9, wherein the color shift of the image is corrected when the color shift correction determination value after the correction becomes equal to or larger than a predetermined value based on the detection result of the means. 16. A print mode designating step of designating a print mode, a plurality of image forming steps of forming an image for each color on a predetermined medium in the designated print mode, and a plurality of colors on the medium. A color image having a color misregistration detection step of detecting a color misregistration of the image formed by the step (1) and a color misregistration correction step of correcting the color misregistration of the image formed on the medium when a new print mode is designated. A method of controlling a forming apparatus, wherein the color image forming apparatus includes a color misregistration correction information storage unit that stores color misregistration correction information for each combination before and after changing a print mode, and the color misregistration correction step. A color image forming apparatus is characterized in that the color misregistration correction information based on the combination before and after the change of the print mode is used to correct the color misregistration of the image formed on the medium. Your way. 17. The toner image forming step of forming a toner image on an image bearing member in a designated print mode in the image forming step; and transferring the toner image formed on the image bearing member onto a predetermined medium. The method of controlling a color image forming apparatus according to claim 16, further comprising a transfer step and a carrying step of carrying the medium to the image carrier. 18. The color misregistration correction step determines whether color misregistration correction processing is necessary or not according to a combination of a print mode before change and a print mode after change. A method for controlling a color image forming apparatus as described above. 19. If the print mode is a mode that can be designated from a plurality of image quality modes and the changed print mode has a lower image quality than the print mode before the change,
19. The method of controlling a color image forming apparatus according to claim 16, wherein the color misregistration correction information is information that does not correct the color misregistration of the image. 20. The print mode is a mode that can be designated from a plurality of image quality modes, and in the color misregistration correction step, the changed print mode has a higher image quality than the print mode before the change. The color shift of the image is corrected.
8. The method for controlling a color image forming apparatus according to any one of items 8 to 8. 21. The color misregistration correction step corrects the color misregistration of the image when a color misregistration correction determination value indicating a degree of progress of fatigue or aging of each part of the color image forming apparatus is equal to or more than a threshold value. The method for controlling a color image forming apparatus according to claim 1 or 2, wherein 22. The color image forming apparatus further comprises threshold value storage means for storing the threshold value, and the threshold value corresponding to the print mode after the threshold value is changed in accordance with the change in the print mode. 22. The method for controlling a color image forming apparatus according to claim 21, further comprising a threshold value changing step of changing to a value. 23. In the color misregistration correction step, a color misregistration correction judgment value indicating the degree of progress of fatigue or aging of each part of the color image forming apparatus is detected by temperature detecting means or humidity detection provided inside the color image forming apparatus. 18. The color image according to claim 16, wherein the color image is corrected based on the detection result of the means, and when the corrected color misregistration correction determination value is equal to or larger than a predetermined value, the color misregistration of the image is corrected. Control method of forming apparatus. 24. A print mode designating step of designating a print mode, a plurality of image forming steps of respectively forming toner images of different colors on a plurality of image carriers, and an intermediate transfer by superimposing the toner images of different colors. Transfer step of transferring to the body, color shift detection step of detecting color shift of an image formed in a plurality of colors on the intermediate transfer body, and when a new print mode is designated, on the intermediate transfer body A method of controlling a color image forming apparatus, comprising: a color misregistration correction step of correcting a color misregistration of an image to be formed, wherein the color image forming apparatus is a combination before and after a change in a print mode and a color deviation at each combination. Color misregistration correction information storage means for storing correction information is provided, and the color misregistration correction step uses the color misregistration correction information based on the combination before and after the change of the print mode to form a pattern on the intermediate transfer member. A method for controlling a color image forming apparatus, comprising correcting a color shift of an image formed. 25. A print mode designating means for designating a print mode, a plurality of image forming means for forming an image for each color on a predetermined medium in the designated print mode, and a plurality of colors on the medium. Color image forming apparatus including a color misregistration detection unit that detects a color misregistration of an image formed by the process described above, and a color misregistration correction information storage unit that stores color misregistration correction information for each combination before and after changing the print mode. When a new print mode is specified, the color misregistration correction information based on the combination before and after the change of the print mode is used to correct the color misregistration of the image formed on the medium. A computer program that functions as a color misregistration correction unit for correction. 26. A recording medium on which the computer program according to claim 25 is stored.