JP2002091119A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming device carrying out resist adjustment by utilizing a small number of patches and correcting variation in density of the patches at the start of generation of the patches and at the finish. SOLUTION: In the color image forming device installed with a multiple number of image forming units, it is constituted so that printing positions of each image forming unit is adjusted, the patches of a resist deviation position when the density is maximum and of a resist deviation position when the density is minimum are generated, the deviated quantity of resist is calculated by a calculation formula from a value of density that is actually detected between them and resist correction is carried out.

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 such as a tandem type, and more particularly to a color image forming apparatus capable of detecting the density of a patch for detecting a registration correction value using an infrared sensor and performing registration correction with a small number of patches. Equipment related.

[0002]

2. Description of the Related Art In recent years, color printers (color image forming apparatuses) have been widely used in conjunction with an increase in the number of personal computers sold. In particular, tandem type color image forming apparatuses have excellent printing speed. , Is attracting attention today. In a color image forming apparatus of this type, four color images including black (K) and three colors of yellow (Y), magenta (M), and cyan (C) are sequentially transferred, and are superposed and fixed. To form an image. In addition, since an image is formed on a transfer medium (paper) that moves in the sub-scanning direction, the alignment of each color requires precision. Further, in the color image forming apparatus, the color tone is also important, and even if the toner density of one color deviates from the reference, the color tone of the composite color becomes different.

For this reason, various methods have been proposed for the color image forming apparatus in order to achieve image matching and color matching. For example, there is a method of actually printing a test chart, visually judging the correction amount, and adjusting the printing position of each color. In addition, a density sensor is placed,
For example, 1 in which the patch position is sequentially shifted with respect to the reference patch
There has also been proposed a method of printing one color patch (registration correction value detection patch), automatically detecting a printing deviation by the sensor, and automatically calculating a correction amount.

[0004]

However, in the above-mentioned conventional method, in the method of actually printing the test chart and visually determining the correction amount, the operation is complicated and time-consuming. On the other hand, in the method using the patch for detecting the registration correction value, for example, ±
In order to obtain a correction range of 8 dots, it is necessary to generate 11 patches for each color in the case of a 2 dot shift, which requires a lot of patch generation time and toner consumption.

Further, the output value of the density sensor periodically and slightly changes in density between the patch generation start side and the patch generation side due to some factor at the time of patch generation, and even if an image is formed on the same photosensitive member. This affects the accuracy of detecting the correction value. Therefore, the present invention provides a color image forming apparatus that uses a small number of patches, corrects a density change between the patch generation start side and the end side, and performs registration adjustment in a tandem type color image forming apparatus. Aim.

[0006]

According to the first aspect of the present invention, there is provided a transfer belt which is wound around at least two rolls of a driving roll and a driven roll and circulates, and which is attached to and detached from an apparatus main body. A plurality of image forming units that are provided freely along the outer peripheral surface of the transfer belt and that form images with toners of different colors, respectively. An electrophotographic color image forming apparatus for batch-transferring a reference color test print pattern having an image formation blank area, forming an image with a print color serving as a reference for image formation, and the reference color test print pattern An adjustment color solid printing pattern that completely fills the image forming blank area, and an adjustment color test that prints an adjustment color having the same width as the image forming blank area of the reference color test printing pattern. Storage means for storing at least a print pattern; and the reference color test print pattern is called from the storage means, transferred to a corresponding image forming unit, and the reference color test print pattern is stored on the transfer belt along the moving direction of the transfer belt. First to form test print pattern image
The reference color test print pattern and the adjusted color solid print pattern are read out from the storage means in a predetermined order and transferred to the image forming unit of the corresponding color to move the transfer belt. Second test print pattern image forming control means for forming a superimposed image of the reference color test print pattern and the adjustment color solid print pattern on the transfer belt along a direction, and the reference color test print from the storage means. The pattern and the adjusted color test print pattern are called in a predetermined order, transferred to the image forming unit of the corresponding color, and the reference color test print pattern and the adjustment are transferred on the transfer belt along the transfer belt moving direction. A third test print pattern image forming control means for forming an overlaid image with the color test print pattern; A density sensor for detecting the density of the image formed on the transfer belt by the test print pattern image forming control means, and the image density value of the reference color test print pattern detected by the density sensor A density level, a density value of a composite image of the reference color test print pattern and the adjustment color solid print pattern as a maximum density level, and the reference color test print indicating a density level between the minimum density level and the maximum density level. This can be achieved by providing a color image forming apparatus that calculates a correction value of an adjustment color based on a density level of a composite image of a pattern and an adjustment color test print pattern and uses the correction value as a registration correction value of the adjustment color.

With this configuration, it is possible to correct the effect of the periodic density fluctuation by using a small number of patches and perform the registration correction. According to the invention as set forth in claim 2, the above-mentioned object is provided so as to be detachably mounted on a transport belt that is wrapped around at least two rolls of a drive roll and a driven roll and circulates, and that is detachably attached to the apparatus main body. An electrophotographic color image having a plurality of image forming units arranged along the outer peripheral surface, each of which forms an image with a different color toner, and sequentially forming a superimposed image on a sheet carried on the transport belt Forming a reference color test print pattern having an image forming blank area, forming an image with a printing color that is a reference of the image forming apparatus, and completely forming the image forming blank area of the reference color test print pattern. At least an adjustment color solid print pattern to be filled and an adjustment color test print pattern for printing an adjustment color having the same width as the image forming blank area of the reference color test print pattern. A storage unit for storing the reference color test print pattern from the storage unit, transferring the reference color test print pattern to the corresponding image forming unit, and transferring the image of the reference color test print pattern on the paper along the moving direction of the transfer belt. The first test print pattern image forming control unit to be formed, the reference color test print pattern and the adjustment color solid print pattern are called from the storage unit in a predetermined order, and transferred to the image forming unit of the corresponding color. A second test print pattern image forming control unit for forming a superimposed image of the reference color test print pattern and the adjustment color solid print pattern on the paper along the moving direction of the transfer belt; and The reference color test print pattern and the adjustment color test print pattern are called in a predetermined order, and the image forming unit of the corresponding color is called. A third test print pattern image forming control means for transferring the reference color test print pattern and the adjustment color test print pattern on the paper along the moving direction of the transfer belt to transfer the transfer image to the printer. A density sensor for detecting the density of an image formed by the first to third test print pattern image formation control means, and the density value of the reference color test print pattern detected by the density sensor is set to a minimum density. Level, a density value of a composite image of the reference color test print pattern and the adjustment color solid print pattern as a maximum density level, and the reference color test print pattern indicating a density level between the minimum density level and the maximum density level. A correction value for the adjustment color is calculated based on the density level of the composite image of the adjustment color test print pattern and a registration correction value for the adjustment color. This can be achieved by providing a color image forming apparatus that performs the following.

This embodiment differs from the first embodiment in that various patterns are printed on paper instead of on a transfer belt. With such a configuration, it is also possible to correct the effect of the periodic density fluctuation by using a small number of patches and perform the registration correction.

According to a third aspect of the present invention, in the first or second aspect of the invention, the correction value of the adjustment color is calculated by setting the image density of the reference color test print pattern to B, The density of the composite image with the adjustment color solid print pattern is A, and the density of the composite image of the reference color test print pattern and the adjustment color test print pattern is α.
In this case, the correction value ΔH is represented by the following equation: ΔH = (α− (A + B) / 2) / (AB) / 10)

In this example, the arithmetic expressions according to claims 1 and 2 are specified, but the arithmetic expressions are not necessarily limited to the above expressions. According to a fourth aspect of the present invention, there is provided a transfer belt which is wound around at least two rolls of a driving roll and a driven roll and circulates and is provided detachably with respect to an apparatus main body. And a plurality of image forming units which are arranged along the outer peripheral surface of the transfer belt and form images with toners of different colors, respectively. A color image forming apparatus, comprising: a first reference color test print pattern having an image formation blank area and forming an image with a print color serving as a reference for image formation; A plurality of types of images to be formed with a predetermined color to be adjusted corresponding to the reference color test print pattern so as to fill the image formation blank area at various ratios with respect to the printing position shift direction. A storage unit for storing at least an adjustment color test print pattern, a second reference color test print pattern having an image formation blank area, and forming an image with a print color serving as a reference for image formation; and The first reference color test print pattern and the plurality of types of adjustment color test print patterns are called in a predetermined order, transferred to the image forming unit of the corresponding color, and transferred on the transfer belt along the moving direction of the transfer belt. To sequentially form a superimposed image of the first reference color test print pattern and the adjustment color test print pattern, and to form an image of the second reference color test print pattern between each of the superimposed images. Test print pattern image forming control means for controlling, a density sensor for detecting the density of the superimposed image formed on the transfer belt, and a density sensor A correction unit that calculates a correction value from the data of each image density to be output, and corrects the density of each image of the superimposed image pattern by the correction value; and performs a resist correction of a corresponding adjustment color according to a result corrected by the correction unit. This can be achieved by providing a color image forming apparatus that performs the image formation.

With this configuration, it is possible to correct the periodic density fluctuation on the patch generation start side and the patch generation end side, and to perform more accurate registration correction. According to the fifth aspect of the present invention, the transport belt is provided so as to be detachably attached to a transport belt that is wrapped around at least two rolls of a drive roll and a driven roll and circulates, and that is detachably attached to an apparatus body. A plurality of image forming units that are arranged along the outer peripheral surface of the image forming apparatus and form images with toners of different colors, respectively. An image forming apparatus, comprising: a first reference color test print pattern having an image formation blank area and forming an image with a print color serving as a reference for the image forming apparatus; In order to fill the image forming blank area at various ratios with respect to the printing position shift direction, a plurality of images formed with a predetermined color to be adjusted corresponding to the reference color test print pattern and adjusting the image forming position. Storage means for storing at least a kind of adjusted color test print pattern and a second reference color test print pattern having an image forming blank area and forming an image with a print color which is a reference of the image forming apparatus; Means for calling out the reference color test print pattern and the plurality of types of adjustment color test print patterns in a predetermined order, transferring them to the image forming unit of the corresponding color, and transferring the transfer print belt on the paper along the moving direction of the transfer belt. Test printing for sequentially forming a superimposed image of the reference color test print pattern and the adjustment color test print pattern, and controlling to form an image of the second reference color test print pattern between each of the superimposed images. Pattern image formation control means, a density sensor for detecting the density of the superimposed image formed on the paper, and each image detected by the density sensor Correction means for calculating a correction value from the degree data, and correcting the density of each image of the superimposed image pattern with the correction value; and forming a color image for performing a resist correction of a corresponding adjustment color according to a result corrected by the correction means. This can be achieved by providing a device.

[0012] This configuration also corrects periodic density fluctuations on the patch generation start and end sides, and
More accurate resist correction can be performed. Claim 6
In the invention according to claim 4 or 5, the calculation performed by the correction means is such that the average value of the image density of the second reference color test print pattern is Avel, and the first reference color test print pattern is Is the density of any one image of P1D1, and the second reference color test print adjacent to the arbitrary one image across the superimposed image of the first reference color test print pattern and the adjustment color test print pattern When the density of the pattern image is P1D2 and the density of the superimposed image with the first reference color test print pattern is RP3, the corrected density RD3 is given by RD3 = RP3- (P1D1 + P1D2) / 2-Avel It is a configuration that can be obtained.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 shows a color image forming apparatus according to the present embodiment, which is an example of a so-called tandem type color printer. In FIG. 1, the printer device 11 is connected to a host device such as a personal computer (not shown) by a cable.

The printer device 11 comprises an upper portion 12 of the apparatus main body and a lower portion 13 of the apparatus main body. An operation panel 14 is provided on the upper portion 12 of the apparatus, and a discharge section 15 for printing paper is formed on the upper surface thereof. I have. The operation panel 14 includes a key operation unit 14a on which a plurality of keys are arranged, and a liquid crystal display 14b for performing display based on display information output from a CPU described later. The print output created by an image forming unit described later is discharged to the paper discharge unit 15 by the rotation of the paper discharge roll 16, and is sequentially stacked on the paper discharge unit 15.

A transport unit for double-sided printing and a paper feed cassette described later are set in the lower portion 13 of the apparatus main body. For example, by opening a lid (not shown) provided on a side surface of the printer apparatus 11, a double-sided printing described later is performed. This is a configuration in which the printing transport unit can be attached and detached. A front cover 17 that can be opened and closed and a paper cassette 18 that is detachable from the lower part 13 of the apparatus are provided in the lower part 13 of the apparatus, and the front cover 17 is opened, for example, for jam clearance or maintenance.

The paper supply cassette 18 is housed at the bottom of the printer 11 of the present embodiment as described above. When replenishing paper to the paper supply cassette 18, for example, by pulling the handle 18a forward, the paper supply cassette 18 is supplied. The paper cassette 18 can be pulled out in the direction of the arrow. FIG. 2 is a cross-sectional view illustrating an internal configuration of the printer device 11 having the above-described external configuration. In FIG. 1, the printer device 11 includes an image forming unit 21, a conveyance unit 22 for double-sided printing, and a paper feeding unit 23. Here, the image forming unit 21 has a configuration in which four image forming units 24 to 27 are arranged side by side. Magenta (M), cyan (C), yellow (Y), They are arranged in the order of black (K). The magenta (M), cyan (C), and yellow (Y) image forming units 24 to 26 are configured to perform color printing by subtractive color mixing, and the black (K) image forming unit 27 is configured to perform monochrome printing. Used for

Here, each of the above image forming units 24-2
Reference numeral 7 includes a drum set C1 and a toner set C2, and has the same configuration except for (color of) the developer stored in the developing container. Therefore, the configuration will be described using the image forming unit 26 for yellow (Y) as an example. The drum set C1 contains a photosensitive drum, a charger, and a cleaner, and the toner set C2 contains a developing roll and toner. The peripheral surface of the photoconductor drum 30 is made of, for example, an organic photoconductive material, and a charger 31a, a print head 31b, and a developing roll 3 are provided near the peripheral surface of the photoconductor drum 30.
1c, a transfer device 31d, and a cleaner 31e are sequentially arranged. The photoreceptor drum 30 rotates in the direction of the arrow, and first charges the peripheral surface of the photoreceptor drum 30 uniformly by applying a charge from the charger 31a. Then, by optical writing based on the print information from the print head 31b, the photosensitive drum 30
Is formed on the peripheral surface of the developing roller 31c, and a toner image is formed by a developing process using the developing roll 31c. At this time, the toner image formed on the peripheral surface of the photosensitive drum 30 is
Of the yellow (Y) toner stored in the printer. The toner image formed on the peripheral surface of the photosensitive drum 30 in this way reaches the position of the transfer unit 31d with the rotation of the photosensitive drum 30 in the direction of the arrow, and moves immediately below the photosensitive drum 30 in the direction of the arrow. It is transferred to the moving paper.

On the other hand, the paper is transported by the paper feed cassette 18, the standby roll 32, the transport belt 33, the drive roll 34, the driven roll 34 ', etc. constituting the above-mentioned paper feed unit 23. The sheet conveyed out of the sheet cassette 18 by the rotation is sent to the standby roller 32, further sent on the conveyor belt 33 at a timing coincident with the toner image, and reaches the transfer device 31 d. Then, the toner image is transferred by the transfer device 31 d, and the sheet on which the toner image is transferred moves on the transport belt 33 in the direction of the arrow according to the movement of the transport belt 33, and is subjected to heat fixing processing in the fixing unit 36.

On the upper surface of the sheet, not only the yellow (Y) toner image but also a drum set C of another color is provided.
The magenta (M) and cyan (C) toner images transferred by the toner set 1 and the toner set C2 are also transferred, and printing of a color according to the subtractive color mixture is performed.

The above-mentioned paper includes not only the paper carried out of the paper feed cassette 18 but also the paper supplied from the MPF tray 19. In this case, the paper is supplied by the paper feed roller 19a.
And the printing process is performed along the above-described route. The fixing unit 36 includes a heat roll 36a,
While the paper P is nipped and conveyed between the above-mentioned heat rolls 36a and 36b, for example, a multi-color toner image transferred to the paper is melted and melted.
Heat-fixed. The cleaner 36c is a heat roll 36a.
Has the function of removing the toner remaining in the toner. The sheet on which the toner image is fixed by the fixing unit 36 is connected to the switching plate 41.
Is transported upward or leftward on the paper.

On the other hand, the double-sided printing transport unit 22 is detachably attached to the apparatus main body, and is a unit to be mounted when performing double-sided printing by the printer device 11 of the present embodiment, and has a plurality of transport rolls 40a to 40e inside. Are arranged. In the case of double-sided printing, the sheet is once sent upward by the switching plate 41. For example, when the rear end of the sheet reaches the transport roll 42, the transport of the sheet is stopped, and the sheet is further transported in the reverse direction. With this control, the sheet is conveyed downward on the left side of the switching plate 41 set at the position indicated by the dotted line,
The paper is conveyed into the paper conveyance path of the conveyance unit 22 for double-sided printing,
The paper is sent by the transport rolls 40a to 40e, reaches the standby roll 32, is sent to the transfer unit at the same timing as the toner image as described above, and the toner image is transferred to the back surface of the paper.

In this embodiment, a density measuring sensor 45 is provided near the driving roll 34 and
The density of the toner image (patch described later) formed on the peripheral surface of is measured. The density measurement sensor 45 is an infrared sensor, and irradiates infrared rays to a patch formed on the peripheral surface of the transport belt 33 to measure the density of the patch.

FIG. 3 is a view showing a state where the upper part 12 of the apparatus main body is opened. As shown in FIG.
Is opened while being kept substantially horizontal with respect to the lower portion 13 of the apparatus main body. Therefore, at the time of opening, the drum set C1 and the toner set C2 can be inserted and removed in a substantially horizontal direction. For example, when replacing the drum set C1, as shown in FIG. 4, the drum set C1 is pulled out to the near side, and a new drum set C1 is inserted. When replacing the toner set C2, as shown in FIG. 5, the user pulls out the toner set C2 and inserts a new toner set C2.
Therefore, in the color image forming apparatus of the present example, the exchange of the drum set C1 and the toner set C2 is easy.

FIG. 6 is a diagram showing an internal circuit configuration in a color image forming apparatus having the above-mentioned mechanism configuration. In the figure, a color image forming apparatus according to the present embodiment includes an interface (I / F) 51, a CPU 52, and an EEPROM.
53, a ROM 54, a print controller 55, a printer printing unit 56, the above-mentioned operation panel 14, and a density measurement sensor (infrared sensor) 45. An interface (I / F) 51 receives print data sent from a host device (not shown) and creates bitmap data of yellow (Y), magenta (M), cyan (C), and black (K). This bitmap data is stored in the frame memory 57.

Here, the frame memory 57 is composed of 57Y, 57M, 57C and 57K corresponding to yellow (Y), magenta (M), cyan (C) and black (K). The bitmap data of yellow (Y) is stored in the storage area 57Y of the frame memory 57, the bitmap data of magenta (M) is stored in the storage area 57M of the frame memory 57, and the bitmap data of cyan (C) is stored. Are stored in the storage area 57C of the frame memory 57, and the black (K) bitmap data is stored in the storage area 57K of the frame memory 57.

The CPU 52 is the color image forming apparatus 1 of this embodiment.
1 is a central control unit that performs printing control and system control, and controls according to a program stored in the ROM 54. The EEPROM 53 stores pattern data of various patches described later, and the ROM 54 stores a printing program and a control program. Also, EE
An arithmetic expression (calculation expression) described later is stored in the PROM 53 or the ROM 54, and the density measurement sensor (infrared sensor) 45
The calculation described later is performed using the density data of the patch read from the.

The CPU 52 inputs an operation signal from the key operation unit 14a provided on the operation panel 14, and
Also, it outputs a display signal to the display unit. The printer controller 55 outputs the bitmap data supplied from the interface (I / F) 51 to the printer printing unit 56. Here, the printer controller 55 outputs data to the printer printing unit 56 for each of yellow (Y), magenta (M), cyan (C), and black (K). For example, the data of yellow (Y) is supplied to the print head 31b of the above-described image forming unit 26, and the magenta (M)
Is supplied to the print head 31b of the image forming unit 24, and the cyan (C) data is
5, and the black (K) data is supplied to the print head 31b of the image forming unit 27.

The printer printing section 56 is composed of print heads 31b of the corresponding colors, etc.
1. Printing of each color described above is performed by the toner set C2. In the color image forming apparatus having the above configuration, the configuration of the patch used in this example will be described below.
It should be noted that the printing of this patch is performed by the transport belt 33 as described above.
Done on.

FIG. 7 is a diagram for explaining a patch (register for detecting a correction value) used in this embodiment. In the figure, a patch 1 is generated in black (black), for example, and is a reference patch for the patch of this example. This patch 1 has a configuration in which a black print area is 20 dots in the width direction, and five black print areas are formed in a grid pattern with a non-print area of 10 dots interposed therebetween.

The patch 2 is a patch in which a color other than black (black) as a reference, for example, magenta (M) is printed on one side, and is printed over black (black). Same as Patch 1. The patch 2 is formed in the same size for cyan (C) and yellow (Y) other than magenta (M).

Next, patch 3 is replaced with patch 2
Are superimposed and printed, and the patch 3 generated at this time is ideally the patch with the highest density. On the other hand, the patch 4 shown in the lower part of FIG. 7 is the same color as the patch 2 described above, and is, for example, a lattice-like magenta (M) color patch. The grid of this patch 4 (magenta (M)
The print width is 10 dots, and the width of the non-print area is 15 dots.
It is a dot. Here, the 10-dot grid (the width of magenta (M) printing) of the patch 4 is the same as the width of the non-printing area of the patch 1. Therefore, when the grid of magenta (M) of patch 4 is accurately located in the non-printing area of patch 1, the state is the same as that of patch 3 described above.

The patch 5 is an example of a case where the patch 4 is superimposed on the patch 1 and printed. In this case, the patch 4 to be synthesized is, for example, a patch 4 having only 5 dots in a portion of the patch 1 where there is no black (black). This indicates printing in which 5 dots protrude and 5 dots overlap patch 1. Therefore, in this case, the intermediate density will be described later.

The pattern data of patch 1, patch 2, and patch 4 is stored in the above-mentioned EEPROM 53,
It is read out under the control of the CPU 52. In this example, a patch having the above configuration is used, and the printing position shift of magenta (M), yellow (Y), and cyan (C) with respect to black (black) is determined by the change in the amount of protrusion of patch 4 with respect to patch 1. To detect.

In the case of this embodiment, the patches to be printed on the conveyor belt 33 are three patterns of black patch 1, black patch 1 and color patch 2, and black patch 1 and color patch 4, and are created for each color. The above-described density measurement sensor (infrared sensor) 45 detects the density of the pattern, and obtains the density information of only the black patch 1 and the patch 3 which is the overprint of the black patch 1 and the color patch 2.
And the density of the patch 5 which is the superimposed printing of the black patch 1 and the color patch 4 are measured.

FIG. 8 shows the above-mentioned patch 1, patch 3, and patch 5.
FIG. 4 is a diagram showing the relationship between the densities of FIG. As shown in the figure, patch 1 (black patch 1) and patch 3 (composite patch of black patch 1 and color patch 2) show a constant value regardless of registration deviation. That is, the concentration measurement sensor (infrared sensor) 45
, The patch density of the lattice-shaped black patch 1 is the lightest, and the detected density level is also the lowest. On the other hand, the density level of patch 3 (a composite patch of black patch 1 and color patch 2) is the highest, and the detected density level is the highest.

In addition, patch 5 which is a print in which 5 dots (half of a maximum of 10 dot shifts) overlap patch 1
Indicates the density between the patch 1 and the patch 3 according to the resist deviation. In this example, for example, when there is no resist displacement,
The value at the center (intermediate density) of patch 1 and patch 3 is shown. In FIG. 7, when the printing of the patch 4 shifts to the left, the density of the patch 5 approaches the density of the patch 1 according to the shift amount, and conversely, when the color shifts to the right, the patch changes according to the shift amount. The density of 5 approaches the density of patch 3.

Here, assuming that the density of the patch 3 is A, the density of the patch 1 is B, and the density of the patch 5 is α, the registration correction value ΔH at that time is obtained by the following equation. ΔH = (α− (A + B) / 2) / (A−B) / 10) This calculation formula is, for example, the above-mentioned EEPR as a program.
Calculation is performed from the patch density detection value stored in the OM 53 or the ROM 54 and detected by the density measurement sensor (infrared sensor) 45. For example, a concentration measuring sensor (infrared sensor) 4
When the detected value by the C.5 is C shown in FIG.
Calculates the density data c read from the density measurement sensor (infrared sensor) 45 in accordance with the above equation, and obtains a registration shift amount + 1 dot indicated by a dotted line in FIG.

A density measuring sensor (infrared sensor) 4
When the detected value by 5 is D shown in FIG. 8, the CPU 52 similarly calculates the density data d read from the density measuring sensor (infrared sensor) 45 in accordance with the above equation,
A resist displacement amount of -2 dots indicated by a two-dot chain line in FIG. 8 is obtained.

As described above, it is possible to detect the registration correction value by performing the calculation from the density change amount of the patch detected by the density measurement sensor (infrared sensor) 45, and to perform the correction irrespective of the registration correction unit with a small number of patches. The detection of the value can be made possible.

In the above-described embodiment, the dot interval of the patches is set to 20, 10 and only 5 dots are protruded in the patch 5 to enable ± 5 dot correction. It may be good, it may be in the middle, and it may be at intervals of 22, 10, etc. The resist may be in the main scanning direction or the sub-scanning direction.

Further, by increasing the number of generated patches, the detection accuracy of the registration correction value can be improved. In the above embodiment, the registration of the color patch for the black patch is determined. However, the registration of the color patch for the color patch may be determined between magenta (M), yellow (Y), and cyan (C).

Further, in the above description of the embodiment, the printing (generation) of the patch is performed on the transfer belt, but may be performed on the paper moving on the transfer belt. <Second Embodiment> Next, a second embodiment of the present invention will be described. It should be noted that also in this example, FIGS.
Has the same basic configuration.

FIG. 9 is a diagram for explaining the present example. In this example,
As in the conventional example, first, 11 resist patches are generated. Then, the patch 1 described above is interposed between these 11 patches.
(See FIG. 7). The reason for generating the patch 1 in this manner is as follows. That is, the color patch (II) shown in FIG. 9 is a patch in which the printing position is sequentially shifted from the black patch (I), and the density of the composite patch (combined patch) (III) is most in the middle. Dark. But,
As described in the conventional example, there is a delicate density fluctuation between the generation start side and the end side of a continuous patch, and the accuracy of the correction value is not accurate. For example, the leftmost patch and the rightmost patch of the combined patch (combined patch) (III) shown in the figure do not always have the same density.

Therefore, a patch (III) ′ shown in FIG. 9 is generated. That is, for the 11 patches (III), the above-mentioned patch 1 (,
Etc.). Therefore, patch (III) 'is 23
Patch rows. FIG.
This is a printing example in which three patches are generated, and the patch density is sequentially detected by the density measurement sensor (infrared sensor) 45 described above. In the example shown in FIG. 10, the patch generation position is a position shifted by 8 mm from the center of the conveyor belt 33, but is not limited to this position.

With the above configuration, the density data detected by the density measuring sensor (infrared sensor) 45 is supplied to the CPU 52, and the CPU 52 calculates the average value of the densities of the 12 patches 1 generated.
Then, the difference from the average value of the density of each patch 1 is used as a correction value of the resist patch sandwiched between the two patches 1.

Here, the average value of the twelve patches 1 is represented by Avel
When the density of patch 1 () shown in FIG. 9 is P1D1 and the density of patch 1 () is P1D2, RD
3 = RP3- (P1D1 + P1D2) / 2-Avel). Note that RP3 indicates the density level of the resist patch.

Incidentally, a diagram for explaining this relationship in more detail is shown in FIG.
It is FIG. For example, in the range of the above-mentioned patches, the average value of the 12 patches 1 is lower than Avel (−ΔD) and the average value of the 12 patches is + ΔD to the density level (RP3) of the resist patch.

Further, the other patches are sequentially processed in the same manner and the density level is corrected, so that the registration adjustment in which the density fluctuation is corrected can be performed. In this example, the registration may be performed in the main scanning direction or the sub-scanning direction. Not only the registration of the color patch with respect to the black patch but also the registration between magenta (M), yellow (Y), and cyan (C) can be performed. The registration of the color patch with respect to the color patch may be determined.

Although the printing (generation) of the patch is performed on the transfer belt in the description of the above embodiment, it may be performed on a sheet moving on the transfer belt.

[0050]

As described in detail above, according to the present invention, the resist adjustment can be performed using a small number of patches. Further, even when a density variation occurs on the patch generation start side and the patch generation end side, registration adjustment in which the variation is corrected can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an external configuration of a so-called tandem type color printer, which is a color image forming apparatus according to an embodiment.

FIG. 2 is a cross-sectional view illustrating an internal configuration of the printer device.

FIG. 3 is a diagram showing a state where an upper portion of the apparatus main body is opened.

FIG. 4 is a diagram illustrating an example in which a drum set is extracted to the front and a new drum set is inserted;

FIG. 5 is a diagram illustrating an example in which a toner set is extracted to the front and a new toner set is inserted.

FIG. 6 is a diagram illustrating an internal circuit configuration in the color image forming apparatus.

FIG. 7 is a diagram illustrating a patch (a patch for detecting a registration correction value) used in the first embodiment.

FIG. 8 is a diagram illustrating a relationship between densities of a patch 1, a patch 3, and a patch 5.

FIG. 9 is a diagram illustrating a patch used in the second embodiment.

FIG. 10 is a printing example in which 23 patches are generated on a transport belt.

FIG. 11 is a diagram illustrating an arithmetic process according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Printer apparatus 12 Upper part of apparatus main body 13 Lower part of apparatus main body 14 Operation panel 14a Liquid crystal display 14b Operation part 15 Paper discharge part 16 Paper discharge roll 17 Front cover 18 Paper feed cassette 18a Handle 19 MPF (multi paper feeder) mounting part 20 Cover 21 Image forming unit 22 Double-sided printing transport unit 23 Paper feed unit 24-27 Image forming unit 30 Photoreceptor drum 31a Charger 31b Print head 31c Developing roll 31d Transfer unit 31e Cleaner 32 Standby roll 33 Transport belt 34 Drive roll 34 'Follower roll 35 Paper feed roller 36 Fixing unit 36a, 36b Heat roll 36c Cleaner 40a to 40e Transport roll 41 Switching unit 42 Transport roll 45 Density measurement sensor 51 Interface (I / F) 52 CP 53 EEPROM 54 ROM 55 the print controller 56 printer printing unit 57,57Y, 57M, 57C, 57K frame memory

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA09 DE02 DE07 EB04 EC03 EC06 ED04 2H030 AA01 AA02 AB02 AD16 BB16 BB36

Claims (6)

[Claims] At least two of a driving roll and a driven roll
A transfer belt wrapped around a plurality of rolls and circulating; a plurality of image forming units which are provided detachably with respect to the apparatus main body, are disposed along the outer peripheral surface of the transfer belt, and form images with toners of different colors, respectively. An electrophotographic color image forming apparatus that sequentially forms superimposed images on the transfer belt and then collectively transfers the images onto a sheet, comprising an image forming blank area, which serves as a reference for image forming. A reference color test print pattern in which an image is formed in a print color, an adjustment color solid print pattern that completely fills the image formation blank area of the reference color test print pattern, and the image formation blank area of the reference color test print pattern. Storage means for storing at least an adjustment color test print pattern for printing an adjustment color of the same width; and calling the reference color test print pattern from the storage means A first test print pattern image forming means for transferring to the corresponding image forming unit to form an image of the reference color test print pattern on the transfer belt along the moving direction of the transfer belt; and The reference color test print pattern and the adjustment color solid print pattern are called in a predetermined order, transferred to the image forming unit of the corresponding color, and transferred to the transfer belt along the moving direction of the transfer belt. Second test print pattern image forming control means for forming a superimposed image of a print pattern and the adjustment color solid print pattern; and a predetermined order of the reference color test print pattern and the adjustment color test print pattern from the storage means. Call with
A third test print for transferring the corresponding color test print pattern and the adjustment color test print pattern on the transfer belt along the moving direction of the transfer belt by transferring the corresponding color to the image forming unit; Pattern image forming control means; and a density sensor for detecting the density of an image formed on the transfer belt by the first to third test print pattern image forming control means. The image density value of the reference color test print pattern is defined as a minimum density level, the density value of a composite image of the reference color test print pattern and the adjustment color solid print pattern is defined as a maximum density level, and the minimum density level and the maximum density level are determined. The reference color test print pattern and the adjustment color test print pattern indicating the density level between Te, and calculates a correction value of the adjustment color, color image forming apparatus characterized by a registration correction value of the adjustment color. 2. At least two of a driving roll and a driven roll.
A plurality of image forming units which are detachably provided to the apparatus main body, are disposed along an outer peripheral surface of the conveying belt, and form images with toners of different colors, respectively. And an electrophotographic color image forming apparatus for sequentially forming superimposed images on paper carried on the transport belt, the image forming apparatus having an image forming blank area and serving as a reference for the image forming apparatus. A reference color test print pattern in which an image is formed in a print color, an adjustment color solid print pattern that completely fills the image formation blank area of the reference color test print pattern, and the image formation blank area of the reference color test print pattern. Storage means for storing at least an adjustment color test print pattern for printing an adjustment color of the same width; and calling the reference color test print pattern from the storage means A first test print pattern image forming control unit that transfers the image to the corresponding image forming unit to form an image of the reference color test print pattern on the sheet along the moving direction of the transfer belt; and The reference color test print pattern and the adjustment color solid print pattern are called in a predetermined order, transferred to the image forming unit of the corresponding color, and the reference color test print is printed on the paper along the moving direction of the transfer belt. Second test print pattern image forming control means for forming a superimposed image of the pattern and the adjustment color solid print pattern; and the reference color test print pattern and the adjustment color test print pattern from the storage means in a predetermined order. call,
A third test print pattern which transfers the reference color test print pattern and the adjustment color test print pattern on the paper along the moving direction of the transfer belt by transferring the corresponding color to the image forming unit; Image forming control means; and a density sensor for detecting the density of an image formed by the first to third test print pattern image forming control means, wherein the reference color test print pattern detected by the density sensor is provided. Is the lowest density level, the density value of the composite image of the reference color test print pattern and the adjustment color solid print pattern is the highest density level, and indicates the density level between the lowest density level and the highest density level. The correction value of the adjustment color is calculated based on the density level of the composite image of the reference color test print pattern and the adjustment color test print pattern.
A color image forming apparatus, wherein a registration correction value of the adjustment color is used. 3. The method of calculating the correction value of the adjustment color, wherein B is the image density of the reference color test print pattern, and A is the density of a composite image of the reference color test print pattern and the adjustment color solid print pattern. The density of the composite image of the reference color test print pattern and the adjusted color test print pattern is α
The correction value ΔH is represented by the following formula: ΔH = (α− (A + B) / 2) / (A−B) / 10). Color image forming device. 4. At least two of a driving roll and a driven roll
A transfer belt wrapped around a plurality of rolls and circulating; a plurality of images provided detachably with respect to the apparatus main body, arranged along the outer peripheral surface of the transfer belt, and each forming an image with a different color toner; An electrophotographic color image forming apparatus, comprising: a forming unit; and sequentially forming a superimposed image on the transfer belt, and then transferring the formed image onto a sheet at once. A first reference color test print pattern in which an image is formed with a print color of
A predetermined adjustment color corresponding to the reference color test print pattern to adjust image formation so as to fill the image forming blank area of the first reference color test print pattern at various ratios with respect to the printing position shift direction. It has a plurality of types of adjustment color test print patterns on which images are formed, and an image formation blank area,
Storage means for storing at least a second reference color test print pattern formed with a print color serving as a reference for image formation; and the first reference color test print pattern and the plurality of types of adjustment colors are stored from the storage means. A test print pattern is called in a predetermined order and transferred to the image forming unit of the corresponding color, and the first reference color test print pattern and the adjustment color are sequentially arranged on the transfer belt along the moving direction of the transfer belt. A test print pattern image forming control means for forming a superimposed image with the test print pattern and controlling to form an image of the second reference color test print pattern between the images of the superimposed image; Calculating a correction value from a density sensor for detecting the density of the superimposed image formed on the image forming apparatus, and data of each image density detected by the density sensor; Color image forming apparatus, wherein the correcting means for correcting the density of each image of the image pattern superimposed by the value, to make a corresponding adjustment color registration correction according to the result corrected by said correction means. 5. At least two of a driving roll and a driven roll
A transport belt that is wrapped around a plurality of rolls and circulates, and a plurality of images that are provided detachably with respect to the apparatus main body, are disposed along the outer peripheral surface of the transport belt, and form images with toners of different colors. An electrophotographic color image forming apparatus that sequentially forms superimposed images on paper carried on the transport belt, the image forming apparatus having an image forming blank area, and a reference for the image forming apparatus. A first reference color test print pattern image-formed in a different print color, and the reference color to fill the image formation blank area of the first reference color test print pattern at various ratios with respect to the printing position shift direction. The image forming apparatus has a plurality of types of adjusted color test print patterns, which are formed with a predetermined color to be adjusted to adjust the image forming position, corresponding to the test print pattern, and an image forming blank area. Storage means for storing at least a second reference color test print pattern formed of an image with a reference print color; and determining the reference color test print pattern and the plurality of types of adjustment color test print patterns from the storage means. And transfer to the image forming unit of the corresponding color to form a superimposed image of the reference color test print pattern and the adjustment color test print pattern sequentially on the paper along the moving direction of the transfer belt. And a test print pattern image forming control means for controlling to form an image of the second reference color test print pattern between each of the superimposed images; and detecting a density of the superimposed image formed on the paper. A correction value is calculated from the density sensor to perform, and data of each image density detected by the density sensor, and each correction value is calculated based on the correction value. Color image forming apparatus, wherein the correcting means for correcting the density of the image, to make a corresponding adjustment color registration correction according to the result corrected by said correction means. 6. The calculation performed by the correction unit is such that the average value of the image density of the second reference color test print pattern is Avel, and the density of any one image of the first reference color test print pattern is P1D1. With the superimposed image of the first reference color test print pattern and the adjustment color test print pattern interposed therebetween, the density of the image of the second reference color test print pattern adjacent to the arbitrary one image is P1D2, The density of the superimposed image on the first reference color test print pattern is represented by R
6. The color image forming apparatus according to claim 4, wherein when P3 is set, the corrected density RD3 is obtained by RD3 = RP3- (P1D1 + P1D2) / 2-Avel).