JPH09185209A - Image forming device and method for correcting color reproducibility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the quality of a print from being deteriorated caused by the color mixture of toner and to suppress developer from being exchanged in an image forming device executing a printing action by using the developer such as the toner. SOLUTION: A test chart is outputted by the printer part of the image forming device (S1) and read. Based on the read result and the output data of the test chart, color difference is obtained (S2). When the color difference σis <=5 (S3), it is judged that the color mixture of the toner is slightly caused. Then, the condition of masking work and a toner replenishment signal are corrected (S4). On the other hand, when the color difference σ is larger than 5 and under 10 (S7), it is judged that the comparatively large color mixture of the toner is caused. Then, the toner is forcibly consumed by executing the prescribed frequency of printing actions only with respect to the color (S9).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms a color image by an electrophotographic method using a plurality of types of toner.

[0002]

2. Description of the Related Art A color copying machine is generally known as an image forming apparatus of this type. For example, the configuration includes an image forming unit corresponding to each of a plurality of types of toner, and each image forming unit forms a different toner image for each color on the photosensitive drum, and sequentially prints these toner images. A color image is formed by superimposing and transferring on a material.

FIG. 1 shows a conventional example of such an electrophotographic color copying apparatus.

In the color copying apparatus shown in the figure, the material 6 to be printed such as paper is stored in two cassettes 61 according to the size thereof, and is accompanied by the operation of image formation (hereinafter also referred to as printing). And is fed from one of the cassettes 61 toward the transport unit. The conveyor belt 31 is suspended between the driving roller 35 and the two driven rollers 36 and 37 to form the above-mentioned conveying portion. Here, the driving roller 35 is rotationally driven by the motor 38, so that the conveyor belt 3
1 can reciprocate between the roller 35 and the rollers 36 and 37. The traveling direction is the belt 31.
It is a direction indicated by an arrow A in the figure on the lower side.

4 along the direction in which the conveyor belt 31 extends
Unit image forming units Pa, Pb, Pc and Pd are provided. These image forming units have the same configuration, and the configuration will be schematically described below by taking the first color image forming unit Pa as an example.

In the image forming unit Pa, a cylindrical image carrier that rotates in the direction of arrow B, that is, the photosensitive drum 1a, is arranged in proximity to the above-mentioned conveyor belt 31. As the photosensitive drum 1a rotates, the photosensitive layer on the surface thereof is uniformly charged by the primary charger 15a, and thereafter, the charged photosensitive layer is exposed to the light image of the yellow component of the original image emitted from the laser diode 16a. By doing so, electrostatic latent images are sequentially formed. The portion on which the latent image is formed is sequentially moved by its rotation to reach the position of the developing device 2a, where it is developed and visualized by the yellow toner supplied from the developing device 2a.

The rotation of the photosensitive drum 1a causes the yellow toner image to reach a transfer portion having a corona charger 3a provided between the drum 1a and the conveyor belt 31. The printed material 6 is conveyed to the transfer portion by the conveying belt 31 at the same timing. Then, by applying a transfer bias to the corona charger 3a, the yellow toner image on the photosensitive drum 1a is sequentially transferred onto the printing material 6 as the photosensitive drum 1a rotates.

Then, as the photosensitive drum 1a rotates,
The toner remaining thereon is removed by the cleaning device 4a, and the next image forming process can be started. On the other hand, the printed material 6 to which the yellow toner image is transferred is
The image forming unit Pb for the second color by the conveyor belt 31.
It is transported to the printing section.

The image forming unit Pb for the second color has the same structure as the image forming unit Pb for the first color described above. In the same manner as described above, latent image formation on the photosensitive drum 1b and development with magenta toner are performed. Then, the obtained magenta toner image is transferred onto the printing material at the transfer portion so as to be superimposed on the first color yellow toner image. Similarly, as the print material 6 is conveyed, the cyan toner image and the black toner image are sequentially superimposed and transferred in the image forming units Pc and Pd, and the toner image 4 is transferred onto the print material.
A color image is formed by superposing the color toner images.

The printed material 6 on which the four color toner images have been transferred is further conveyed and discharged by the separation charge eliminator 32.
It is separated from the conveyor belt 3 and sent to a fixing device 5 having a pair of fixing rollers 51 and a pressure roller 52. Here, the transfer toner image is fixed by pressurization and heating by the nip portion of the rollers 51 and 52 which are normally heated to a predetermined temperature. After that, the printed material 6 is
It is ejected outside the copier.

[0011]

However, when printing is performed by the copying apparatus of the above-mentioned conventional example, the print quality may be deteriorated due to the mixture of toners of different colors.

For example, it may be unavoidable that the toner is scattered to some extent in the apparatus, but when the scattered toner reaches an image forming unit of another color, it adheres onto the photosensitive drum in the above-described image forming process. Sometimes. Also,
After the toner is transferred to the print material, the transferred toner may be retransferred from the print material to the photosensitive drum in the image forming unit on the downstream side.

In such a case, in particular, when the toner adhering to the photosensitive drum due to retransfer or the like cannot be completely removed by the cleaning device, the adhering toner is transferred to the developing device as the photosensitive drum rotates. Then, the toner on the photosensitive drum is mixed with the toner in the developing device due to the proximity of the developing device and the photosensitive drum. When such toner mixing is repeated for a long period of time, the color mixture in the printed image becomes so noticeable that accurate color reproduction cannot be performed.

Further, for the purpose of downsizing the image forming apparatus and extending the life of the photosensitive drum, a structure without a cleaning device having an elastic blade, that is, a so-called cleaningless image forming apparatus is also proposed. However, in such a device, the problem of color mixing becomes more remarkable.

FIG. 2 is a diagram showing such an image forming apparatus.

As shown in the figure, LE as an exposure light source
D9a to 9d directly irradiate the corresponding photosensitive drums with light sources of respective color components, and the photosensitive drums 1a to 1d are charged by a contact charger provided in contact with the corresponding drum. 14a to 14d.

In the case of such a configuration, it is more difficult to completely eliminate the retransfer of the toner from the printing material to the photosensitive drum as described above, and the deterioration of the printing quality due to the color mixture as described above is likely to occur.

When the print quality is deteriorated due to the color mixture as described above, a measure that can be taken in the conventional apparatus is to replace the toner having the color mixture. However, in this case, even though there is still a sufficient amount of toner to be used, it will be replaced.
As a result, the life of the developer is shortened.

The present invention has been made to solve the above problems, and an object of the present invention is to enable stable color reproduction over a long period of time and to improve the life of the developer. An object is to provide an image forming apparatus.

[0020]

According to the present invention, there is provided:
In an image forming apparatus that prints on a printing material using a plurality of types of printing agents, a printing unit that performs printing using the plurality of types of printing agents, a printing result by the printing unit, and a printing result At least one of the plurality of types of printing agents is used when the printing means performs printing based on a comparison value calculation means for obtaining a comparison value by comparing the generated print data and the comparison value obtained by the comparison value calculation means. With respect to the type, a printing agent supply control means for controlling the supply amount and color processing condition is provided.

[0021] In another aspect, in an image forming apparatus that prints on a material to be printed by using a plurality of types of printing agents, a printing means for performing printing by using the plurality of types of printing agents, and the printing means. Reading means for reading a print result by the reading means, a comparison value calculating means for obtaining a comparison value by comparing the reading result by the reading means and print data which has generated the printing result for the reading, and the comparison value calculating means. When the printing means prints based on the comparison value obtained by the means,
Printing agent supply control means for controlling the supply amount of at least one of the plurality of types of printing agents;
It is characterized by having.

In still another aspect, in an image forming apparatus that prints on a material to be printed using a plurality of types of printing agents, a printing means for performing printing using the plurality of types of printing agents, and the printing means. The comparison value calculating means for obtaining a comparison value by comparing the print result by the print data and the print data producing the print result, and the comparison value obtained by the comparison value calculating means are the first reference value and the first reference value. A judging means for judging in which range the second reference value is larger than the value, and when the judging means judges that the range is equal to or less than the first reference value, When the printing unit prints, the supply amount of at least one of the plurality of types of printing agents is controlled, and the determination unit is greater than the first reference value. When it is determined that less than or equal to the second reference value is characterized in that comprises a control means for causing a predetermined amount of printing to said printing means using only the type of printing agent according to the comparison value.

[0023] In still another aspect, an image forming apparatus for printing on a material to be printed by using a plurality of types of printing agents comprises a printing means for performing printing by using the plurality of types of printing agents, and the printing is performed. A comparison value is obtained by comparing the print result by the printing means and the print data that has generated the printing result, and when the printing means performs printing based on the comparison value, at least one of the plurality of types of printing agents is used. about,
It is characterized by having a color reproducibility correction mode for controlling the supply amount.

In still another aspect, in an image forming apparatus for printing on a printing material using a plurality of types of printing agents, a printing means for performing printing using the plurality of types of printing agents is provided, and the printing is performed. A comparison value is obtained by comparing the print result by the printing means and the print data that has generated the printing result, and when the printing means performs printing based on the comparison value, at least one of the plurality of types of printing agents is used. about,
It is characterized by having a color reproducibility correction mode for controlling the supply amount.

In still another aspect, the printing means is an electrophotographic method means, and the printing agent is a developer having toner.

According to the above configuration, since the supply amount of the printing agent is controlled based on the comparison value between the print result and the print data, when the above-mentioned comparison value fluctuates due to color mixture in the printing agent, the value is changed. It is possible to change the amount of the printing agent at the time of printing according to the above, and thus it is possible to cancel the change in the print density due to the color mixture.

When the comparison value is equal to or more than the predetermined value, the mixed color printing agent can be forcibly consumed, so that the mixed color state can be eliminated.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a schematic side view showing the structure of the copying apparatus according to the embodiment of the present invention.

As shown in the figure, the copying apparatus of this embodiment is mainly composed of a reader section A and a printer section B arranged below the reader section A.

The reader unit A is constructed as follows.

That is, the original 101 placed on the original table glass 102 is illuminated by the light source 103 and the optical system 1
An image is formed on the CCD sensor 105 via 04. CCD
The sensors 105 are arranged in three rows and are CCs corresponding to red (R), green (G), and blue (B), respectively.
It has a D line sensor group and generates R, G, and B color component signals. The reading optical system unit including the elements below the light source 103 is scanned in the direction of the arrow in the drawing, and the original 10 is scanned.
The image or the like on 1 is converted into an electric signal data string for each scanning line.

In order to determine the white level of the abutting member 107 for preventing the document from being placed obliquely by placing the position of the document on the platen glass 102 and the CCD sensor 105, A reference white plate 106 for shading the CCD sensor 105 in the thrust direction is arranged.

The image signal obtained by the CCD sensor 105 is subjected to image processing such as color conversion by the reader image processing section 108, and then sent to the printer control section 109 of the printer section B and subjected to predetermined processing.

FIG. 4 is a block diagram showing the configuration of the image processing unit 108 of the reader unit A described above in terms of the flow of image signals to be processed.

As shown in the figure, the image signal output from the CCD sensor 105 is first converted into the analog signal processing section 20.
1 is input, and after gain adjustment and offset adjustment are performed there, the A / D converter 202 converts each color signal into 8-bit digital image signals R1, G1, B1. After that, in the shading correction unit 203, a known shading correction using the read signal of the reference white plate 106 is performed for each color.

In the figure, the clock generator 211
Generates a clock for each pixel with respect to the image reading timing of the reader unit A. Main scanning address counter 2
12 counts the clocks from the clock generator 211 to generate a line (main scanning) address output. Then, the decoder 213 decodes the main scanning address from the main scanning address counter 212, and represents a valid area in a CCD driving signal of a line unit such as a shift pulse or a reset pulse or a 1-line read signal from the CCD. Signal and line sync signal HSYNC. The main scanning address counter 212 is HSYNC.
It is cleared by the signal and the counting of the main scanning address of the next line is started.

In the line delay circuit 204, since each line sensor of the CCD sensor 105 is arranged at a predetermined distance in the direction (sub scanning direction) orthogonal to the scanning direction (main scanning direction), the sub scanning is performed. Corrects spatial deviations in direction. Specifically, each of the R and G signals is delayed from the B signal by a timing corresponding to the shift in the sub-scanning direction, and is output.

The input masking section 205 performs color space conversion on the signal in which the spatial displacement of the CCD sensor is corrected. That is, here, the read color space determined by the spectral characteristics of the R, G, and B color filters in the CCD sensor is converted into the standard color space of NTSC.
The conversion is performed by the matrix operation as in the following equation.

[0040]

[Equation 1]

Further, the light quantity / density conversion section (LOG conversion section) 206 is composed of a look-up table ROM, whereby the converted luminance signal R of the color space is obtained.
4, G4, B4 are converted into density signals C0, M0, Y0. The memory 207 performs data compression processing on C0, M0, and Y0 and stores it. Then, in synchronization with the image formation of the Y, M, C, and K image forming units, C1, M1, Y1, and C are formed.
2, M2, Y2, C3, M3, Y3 and C4, M4
Y4 is output in parallel. That is, the image data is output for the misregistration amount in the image forming unit.

Next, in the masking and UCR circuit 208, first, undercolor removal processing (UCR) is performed based on the signals C1, M1 and Y1, and the signal K1 relating to black color is converted to the minium function min (M1, C1, Y1). Generated by.

Next, based on the signal K1 and the signals C1, M1 and Y1, the matching between the spectral distribution of the color toner and the spectral characteristic of the CCD used in the reading optical system or the spectral characteristic of the color separation filter is optimized. Therefore, the masking process is performed by the matrix calculation of the following equation.

[0044]

[Equation 2]

The γ correction circuit 209 outputs the signal Y after the above processing.
Density correction is performed on 2, M2, C2, and K2 so as to match the ideal gradation characteristics of the printer unit B. Further, the spatial filter processing unit (output filter) 210 performs processing such as edge enhancement and smoothing.

The image signal thus processed is sent to the printer control section 109 of the printer section B, and gradation printing is performed by driving the laser with a pulse width corresponding to these signal values.

In FIG. 4, reference numeral 214 is a CPU for executing the control of the above-described processing in the reader unit A, and 215 is an R.
AM and 216 respectively represent ROMs. Reference numeral 21
Reference numeral 7 denotes an operation unit of the reader unit A, which has a display 218.

Next, the printer section B will be described.

As shown in FIG. 3, the mechanical structure of the printer unit B (the structure of the printer engine) is the same as that shown in FIG. 2 shown as a conventional example. Therefore, the same symbols are given to the similar elements. Will be attached and their description will be omitted.

The printer section shown in FIG. 3 is of the so-called cleaningless type similar to that described in FIG. 2, and the present invention is effective when applied to an image forming apparatus of this type. However, it is needless to say that the present invention can be applied to the type provided with the cleaning device shown in FIG.

FIG. 5 is a block diagram showing a schematic configuration of the printer control unit 109 and the printer engine unit 100 in the printer unit B shown in FIG.

As shown in FIG. 5, the printer control unit 109 has a CPU 128 and the like, performs predetermined image processing based on the image data and the like transferred from the reader unit A, and
Control associated with the printing operation is performed as described later with reference to FIG. That is, the lookup table (LUT) 1
A pulse width modulation circuit (PWM) 126 performs a predetermined density conversion on the image data transferred from the reader unit A.
Converts the density converted data into pulse width data for driving the laser and supplies the pulse width data to the LD driver 127. Then, the LD driver 127 drives the laser light emitting elements (LEDs) 9a to 9d of the printer engine unit 100 based on the pulse width data.

When a predetermined test pattern as described later is printed, the test pattern memory 1
The test pattern stored in 31 is supplied to the pattern generator 129, converted into density data there, and then supplied to the pulse width modulation circuit.

Further, the CPU 128 controls the driving of the developing devices 2a to 2d and the contact charging devices 14a to 14d of the printer engine section 100 during the printing operation.

FIG. 6 is a block diagram showing a flow of processing of an image signal in the configuration shown in FIG.

A luminance signal of the image is obtained by the CCD 105, and this signal is converted into a density signal in the reader image processing unit 108. This image signal corrects the density fluctuation due to the γ characteristic of the printer engine unit, and as a result, the density of the original image and the density of the output image match so that the LUT 12
At 5, the density characteristics are converted.

FIG. 7 is a 4-limit chart showing how gradation is linearly reproduced by the above-mentioned density conversion and the like.

In the figure, the quadrant I shows the reading characteristics of the reader unit A for converting the document density into the density signal, and the quadrant II is the LUT for converting the density signal into the laser output signal.
125 shows the conversion characteristics of the image forming apparatus, the third quadrant shows the printing characteristics of the printer section B for converting the laser output signal to the output density, and the fourth quadrant shows the relationship between the original density and the output density. The key reproduction characteristics are shown. Since the number of gradations in these conversions is processed by an 8-bit digital signal, it is 256 gradations.

As is apparent from the figure, in the copying apparatus of the present embodiment, in order to make the total gradation characteristic in the fourth quadrant linear, in order to make the gradation characteristic linear in the printer characteristic in the third quadrant, Correction is performed by the LUT 125 in the IV quadrant. Although a predetermined value is input to the LUT 125 based on the characteristics of the photosensitive drum and the printer due to the characteristics of reduction, etc., new data may be stored again by performing appropriate calculation depending on the usage status of the apparatus.

The image signal whose density has been converted by the LUT 125 is converted into a signal corresponding to the dot width by the pulse width modulation (PWM) circuit 126 and sent to the laser driver 127 which controls the on / off of the laser. In this embodiment, the gradation reproduction method by pulse width modulation processing is used for all the colors Y, M, C, and K.

An example of the color reproducibility stabilizing process of the present invention based on the configuration of the apparatus of the present embodiment shown above will be described below.

FIG. 8 shows an example of the processing, and the procedure of the processing started by pressing the mode setting button called automatic color reproducibility correction provided on the operation unit 217 (see FIG. 4). It is a flowchart showing. This process is executed by the CPU 214 of the reader unit A (see FIG. 4) and the CPU 128 of the printer unit B (see FIG. 5).

When the operator presses the mode setting button to start the process of the automatic color reproducibility correction mode, the display 218 (see FIG. 4) is first displayed in step S1.
A print start button 81 for activating the print of the test print 1 is displayed on the top (FIG. 9).
(A)). On the other hand, when the operator presses the button, the image of the test print 1 shown in FIG. 11 is printed out by the printer unit B. It should be noted that during this print output, the display shown in FIG. 9C is displayed on the display 218. It should be noted that at the time of print output, the presence or absence of a sheet for printing the test pattern 1 is determined, and if there is no sheet, a warning display as shown in FIG. 9B is displayed.

Further, the copying apparatus of this embodiment is provided with a plurality of paper cassettes, and a plurality of paper sizes such as B4, A3, A4 and B5 can be selected. However, as the print paper used in this mode, so-called large size paper is used in order to avoid an error due to an error between vertical placement and horizontal placement during the reading operation by the operator. That is, using B4, A3, 11 × 17, LGR,
Is set.

The test pattern 1, as shown in FIG. 10, corresponds to various values of M, C, Y and Bk signals.
Patterns 301 through C, Y, and Bk of each density combination
This is an output of 365. Of these, pattern 30
Reference numerals 2, 303, 304, and 305 denote maximum density patches of M, C, Y, and Bk, respectively, which correspond to 255 levels of density signal values. The pattern 301 is a black band for position adjustment / confirmation.

Referring again to FIG. 8, when the test print 1 is output as described above, in step S2, as shown in FIG.
1 (a) is displayed, the test print 1 is placed on the platen glass 102, and the reading start button 91
Prompt to press. On the other hand, the operator sets the test pattern 1 on the platen glass 10 as shown in FIG.
2 (see FIG. 3), and when the reading start button 91 is pressed, the reading operation of the test print 1 is executed. At this time, the display shown in FIG. 11B is displayed on the display 218.

When the test print 1 is placed on the platen, as shown in FIG. 12, the wedge-shaped mark T on the upper left side is a mark for abutting the document on the platen, and the test pattern 1 strip is applied. The pattern 301 is the hitting mark T
Place it so that it is on the side and that there are no mistakes on the front and back. Along with this, on the display 218 of the operation panel, as shown in FIG.
The message shown in (a) is displayed. By doing so, it is possible to prevent a control error due to a misplacement.

Further, in the reader unit A, the patterns 302 to 3
When 65 is read, the scanning is gradually performed from the abutting mark T, and the first density gap point is obtained at the corner of the pattern 301 (point A in FIG. 13). The positions of the patches 302 to 365 are determined and the density values of the patterns 302 to 365 are read.

The display shown in FIG. 11 (b) is displayed during reading, and the message shown in FIG. 11 (c) is displayed when the test print 1 cannot be read due to incorrect orientation or position. When it is displayed that the reading is impossible, the operator places the test print 1 again and presses the reading key 92 to perform the reading.

In step S2, the color difference δ is calculated as follows based on the read result.

That is, R, G, obtained as a result of reading
The value of B is changed to (the line-delayed signals R3, G in FIG.
3, B3) Convert to CIE1976L ^* a ^* b ^* space chromaticity value. It should be noted that this conversion is known, and the description thereof is omitted here. Then, the patterns 302 and 30
3, 304, 305, that is, the maximum density patch of each color of M, C, Y, Bk, from the chromaticity value of the L ^* a ^* b ^* space, the value at the time of reading the test print on the a ^* -b ^* plane The color difference δ between this and the chromaticity value at the time of creating the test print, which was previously obtained on the same plane

[0072]

(Equation 3)

Calculate

Next, in step S3, the color difference δ between these colors is calculated.
The maximum of _M , δ _C , δ _Y , and δ _Bk is 0 ≦ δ ≦
Determine if it is 5. If a positive decision is made here,
In step S4, the following processing is performed.

First, the pattern 30 on the test print 1
Patterns 3 obtained by processing the values of M, C, Y, and Bk signals obtained in advance for 2 to 365 and the read data
The values of M ′, C ′, Y ′, and Bk ′ corresponding to 02 to 365 are obtained, and the parameters of the matrix shown in the above equation (2) are calculated from these values by the least squares method known as a known method. Calculate and reset it.

When the correction of the toner replenishment signal in the developer density control is simultaneously performed, a more preferable result can be obtained.

That is, a so-called two-component developer containing toner and carrier particles is used as the developer, and the concentration of the developer is controlled by an optical system or an inductance system or by outputting a patch on a drum or a conveyor belt. When performing, the toner replenishment signal in this density control is corrected according to the above-mentioned color differences δ _M , δ _C , δ _Y , δ _Bk (ATR control value correction). In this correction, when the toner of another color is mixed in the developing device, the apparent developer concentration increases (specifically, the ratio of the toner to the carrier in the developer increases), and the toner of the original color remains in the developer. This is to prevent the above-mentioned deterioration in print quality due to a decrease in the ratio in the above.

That is, it was confirmed by the studies and experiments by the present inventors that there is a certain relationship between the color difference obtained as described above and the print density difference, that is, the toner density difference in the developer. ing.

Specifically, in the developer used in this embodiment, for example, when the reproduced print density is 1.5 and the color difference δ is 5, this difference is about 0. 2. The toner density in the developer corresponds to about 3% of the set center value (note that the variation ratio with respect to the set center value is constant regardless of the print density).

Therefore, in the present embodiment, with respect to the toner replenishment signal value HS,

[0081]

## EQU4 ## The correction represented by HS '= HS × (1 + 0.006δ) is performed.

When the toner replenishment signal is corrected as described above, the parameter values of the matrix shown in the reset equation (2) are gradually changed according to the corrected number of sheets. Further, color reproducibility can be stably obtained.

If the result of judgment 1 in step S3 is negative,
That is, when the color difference δ is larger than 5, first, a parameter N indicating the number of times such determination is made in step S5 is performed.
Is incremented by 1 and then at step S6 this number N
Is 5 or more. When N is 5 or more, that is, when the determination that the color difference δ is 5 or more continues for five times or more, the process proceeds to step S8, the display shown in FIG. 13B is displayed, and the determined color is developed. Encourages the exchange of agents,
This processing procedure ends.

In the case of negative determination in the determination 2 in step S6,
That is, if it is still less than 5 times that the color difference δ is larger than 5, the process proceeds to step S7.

Here, it is determined whether or not δ is 5 <δ ≦ 10, and if the determination is affirmative, the process proceeds to step S9, and only for the colors whose color difference δ is within the above range of 5 <δ ≦ 10,
Predetermined number of full copies at maximum print density, eg A
Print out about 10 to 20 sheets of 4 size paper.

By doing so, the mixed color toner in the developer can be forcibly consumed and eliminated. At this time, as shown in FIG. 13A, a message "Currently, color reproducibility restoration work is in progress." Is displayed. After the process of step S9 is completed, the process returns to step S1 to check whether or not the toner after the forced consumption is in the proper state.

On the other hand, if a negative decision is made in step S7, the operation proceeds to step S8, and for the color having the color difference δ of 10 <δ as described above, "○" as shown in FIG.
Please replace the color developer "message and call for service.

By performing the above-described processing, the color reproducibility of the full-color copying machine can be stably obtained over a long period of time. Further, conventionally, when the toner of another color is mixed with the developer, the color reproducibility is deteriorated,
Although the developer must be replaced, according to the above-described embodiment of the present invention, by correcting the masking coefficient and the toner replenishment signal as described above, the print quality is improved even if a small amount of toner is mixed. Can be suppressed. Further, even if the deterioration of the print quality becomes relatively large, it is possible to forcibly consume and eliminate the mixed color toners that are the cause of the deterioration.
It is not necessary to replace the developer frequently, which makes it possible to extend the life of the developer.

By the way, this automatic color reproducibility stabilizing mode is constructed so that it can be appropriately performed by a service person or an apparatus operator. Further, it goes without saying that the apparatus itself may display a message for performing this mode for each usage status, for example, for every certain number of used sheets.

Further, in the present embodiment, when some judgments are made, the predetermined operation is carried out when the color difference δ is the above-mentioned value. Is not limited to the above,
It goes without saying that it can be appropriately changed according to the performance of the full-color image forming apparatus.

In the present embodiment, the test section outputs the test pattern and the reader reads the output test pattern to detect the color reproducibility of the image forming apparatus. As shown in FIG. 15, the chromaticity value detecting device 71,
72, or a chromaticity value detection device 73 near the photosensitive drum.
If a (73b, 73c, 73d) is provided and the test pattern is directly recorded on the photosensitive drum or the conveyor belt without outputting the test print and these are read by the chromaticity value detection device, The reproducibility recovery mode is more preferable because it can be easily performed.

[0092]

As described above, according to the present invention, since the supply amount of the printing agent is controlled based on the comparison value between the print result and the print data, color mixture occurs in the printing agent and the comparison value becomes When it fluctuates, it is possible to change the amount of the printing agent at the time of printing according to the value, and it is possible to cancel the change of the printing device due to the color mixture.

When the comparison value is equal to or more than the predetermined value, the mixed color printing agent can be forcibly consumed, and the mixed color state can be eliminated.

As a result, stable and good color reproducibility can be obtained over a long period of time. Further, since the interval for exchanging the printing material can be extended, it is possible to extend the life of the printing material.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a conventional example of a copying apparatus.

FIG. 2 is a schematic side view showing another conventional example of a copying apparatus.

FIG. 3 is a schematic diagram showing a configuration of a copying apparatus according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a reader image processing unit of the apparatus of this embodiment shown in FIG.

5 is a block diagram showing a configuration of a printer control unit of the apparatus of this embodiment shown in FIG.

6 is a block diagram showing the flow of image signals in the apparatus of this embodiment shown in FIG.

FIG. 7 is a diagram for explaining density conversion in the apparatus of this embodiment.

FIG. 8 is a flowchart showing a processing procedure of an automatic color reproducibility correction mode according to an embodiment of the present invention.

9A to 9C are diagrams showing display examples in the above processing.

FIG. 10 is a schematic diagram showing a test pattern used in the above processing.

FIG. 11 is a diagram showing a display example in the above processing.

FIG. 12 is a diagram showing how to place a test pattern in relation to the above processing.

13A and 13B are diagrams showing display examples in the above processing.

FIG. 14 is a schematic side view showing another example of an image forming apparatus to which the present invention can be applied.

FIG. 15 is a schematic diagram showing still another example of an image forming apparatus to which the present invention can be applied.

[Explanation of symbols]

 1a, 1b, 1c, 1d Photosensitive drum 2a, 2b, 2c, 2d Developing device 9a, 9b, 9c, 9d LED (exposure light source) 14a, 14b, 14c, 14d Contact charger 71, 72, 73a Chromaticity value detecting device 100 Printer Engine Unit 105 CCD Sensor 108 Reader Image Processing Unit 109 Printer Control Unit 125 LUT 126 Pulse Width Modulation Circuit 127 LD Driver 128, 214 CPU 129 Pattern Generator 131 Test Pattern Memory 218 Display

Claims (8)

[Claims] 1. An image forming apparatus for performing printing on a printing material using a plurality of types of printing agents, a printing unit for performing printing using the plurality of types of printing agents, and a printing result by the printing unit. A comparison value calculation unit that obtains a comparison value by comparing the print data that has produced the print result, and a plurality of types of the plurality of types when the printing unit performs printing based on the comparison value that the comparison value calculation unit obtains. An image forming apparatus comprising: a printing agent supply control unit that controls a supply amount and a color processing condition of at least one type of printing agent. 2. The image forming apparatus according to claim 1, wherein the color processing condition is a masking coefficient. 3. An image forming apparatus for printing on a printing material using a plurality of types of printing agents, a printing unit for performing printing using the plurality of types of printing agents, and a printing result by the printing unit. A reading means for reading, a comparison value calculating means for obtaining a comparison value by comparing the reading result by the reading means with print data which has produced a printing result for the reading, and a comparison obtained by the comparison value calculating means. An image forming apparatus comprising: a printing agent supply control unit that controls a supply amount of at least one of the plurality of types of printing agents when the printing unit performs printing based on a value. 4. An image forming apparatus for performing printing on a printing material using a plurality of types of printing agents, a printing unit for performing printing using the plurality of types of printing agents, and a printing result by the printing unit. , A comparison value calculating unit that obtains a comparison value by comparing the print data that generated the print result, and a comparison value that the comparison value calculating unit obtains are larger than the first reference value and the first reference value. When the determination means determines which range is with respect to a certain second reference value, and when the determination means determines that the range is less than or equal to the first reference value, the printing means prints based on the comparison value. When performing, the supply amount of at least one of the plurality of types of printing agents is controlled, and the determination means is greater than the first reference value and the second reference value. When it is determined that the lower the image forming apparatus being characterized in that comprises a control means for causing a predetermined amount of printing to said printing means using only the type of printing agent according to the comparison value. 5. An image forming apparatus for printing on a printing material using a plurality of types of printing agents, comprising printing means for performing printing using the plurality of types of printing agents, and a printing result by the printing means. And a print value that has produced the print result are compared to obtain a comparison value, and when the printing means performs printing based on the comparison value, the supply of at least one of the plurality of types of printing agents is performed. An image forming apparatus having a color reproducibility correction mode for controlling the amount. 6. An image forming apparatus for performing printing on a printing material using a plurality of types of printing agents, a printing unit for performing printing using the plurality of types of printing agents, and a printing result by the printing unit. , A comparison value calculating unit that obtains a comparison value by comparing the print data that has produced the print result, and if the comparison value obtained by the comparison value calculating unit is greater than or equal to a predetermined reference value, An image forming apparatus comprising: a control unit that causes the printing unit to perform a predetermined amount of printing using only the type of printing agent. 7. The image forming apparatus according to claim 1, wherein the printing unit is an electrophotographic system unit, and the printing agent is a developer having a toner. 8. A color reproducibility correction method of an image forming apparatus for printing on a printing material using a plurality of types of printing agents, wherein a printing means for performing printing using the plurality of types of printing agents is prepared. A color reproduction having a step of controlling a supply amount of at least one of the plurality of kinds of printing agents when the printing means performs printing based on a printing result of the printing means. Sex correction method.