JP3496548B2 - Color image forming equipment - Google Patents

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 provided with a color deviation detecting mechanism in a registration mechanism of a tandem engine type color image forming apparatus and a color deviation detecting method for the color image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus using a conventional electrophotographic system, a uniform electrostatic charge of about 1 millicoulomb per square centimeter is applied to the surface of a photosensitive drum, and the photosensitive member is exposed according to image information. The charge of the irradiation part is released to the photoconductor drum substrate, and the resulting electrostatic charge distribution forms an image (electrostatic latent image). This electrostatic latent image is developed with colored charged particles (toner particles). Then, a powder image of the toner particles is formed by toner development to form a powder image, and the powder image is transferred to a sheet material or the like and then fused and fixed by applying heat or other energy to form an image. Is being formed.

On the other hand, with the colorization of the image, a plurality of independent images are formed on the respective photosensitive drums by the toner phenomenon to form a powder image of each color of a cyan image, a magenta image, a yellow image, and more preferably a black image. A tandem engine type color image forming apparatus is also proposed which has a forming station and superimposes and synthesizes the powder image formed on each photoconductor drum on the intermediate transfer material at the transfer position of each color powder image. There is. The tandem engine type color image forming apparatus has an advantage that it is possible to speed up image formation because images are formed in parallel for each color.

However, in the case of a tandem engine type color image forming apparatus, each powder image formed at a different image forming station is displaced due to a positional error or a timing deviation between the image forming stations, resulting in color change. A gap occurs. In order to manufacture a high quality color image forming apparatus, such a color shift becomes a very serious problem, and therefore a technique for performing color shift correction (registration) is required.

FIG. 1 is a configuration diagram of a conventional color image forming apparatus, and FIG. 2 is a diagram showing types of color misregistration in a general color image forming apparatus.

In FIG. 1, the conventional color image forming apparatus is arranged so that four image forming stations Pa, Pb, Pc and Pd are arranged side by side in contact with the upper portion of the intermediate transfer belt 7 which is rotated by driving rollers 14a and 14b. Each image forming station has photoconductor drums 1a, 1b, 1c, and 1d that come into contact with the intermediate transfer belt 7 attached to the main body of the color image forming apparatus. Around the photosensitive drums 1a, 1b, 1c, 1d, charging means 2a, 2b, 2c, 2d for giving an electrostatic charge to the photosensitive drums are arranged. Image forming stations Pa, Pb, Pc,
An exposure unit 3 which is a scanning optical system for forming an electrostatic latent image by exposing the photosensitive drums 1a, 1b, 1c, and 1d charged by the charging unit with light according to image information is arranged above Pd. It is set up. In addition, the photosensitive drums 1a, 1b, 1
Around the c and 1d, developing means 4 for developing the electrostatic latent image formed by exposure with colored toner particles to form a powder image.
a, 4b, 4c, 4d, developing means 4a, 4b, 4c, 4
Transfer means 5 for transferring and synthesizing the powder images formed in step d on the intermediate transfer belt 7 at the transfer position of the powder images of the respective colors.
a, 5b, 5c, 5d, transfer means 5a, 5b, 5c, 5
Cleaning means 6a, 6b, 6c, 6 for cleaning the surfaces of the photosensitive drums 1a, 1b, 1c, 1d after the powder images are transferred onto the intermediate transfer belt 7 by d.
d are arranged respectively.

The intermediate transfer belt 7 moves in the direction of the arrow A shown in FIG. 1, and the photosensitive drums 1a, 1b, 1c, 1d.
Rotates in the direction of arrow B shown in FIG. 1 without sliding on the intermediate transfer belt 7.

The image forming operation of the conventional color image forming apparatus having the above construction will be described below. First, in the image forming station Pa, the surface of the photosensitive drum 1a is uniformly charged by electrostatic charge by the charging unit 2a, and then the electrostatic latent image corresponding to the image information of the black component is formed on the photosensitive drum 1a by the exposure unit 3K. Is formed. The electrostatic latent image is developed on the photosensitive drum 1a as a powder image of black toner particles by the developing unit 4a, and the powder image is transferred as a black toner image on the intermediate transfer belt 7 by the transfer unit 5a. It Photoconductor drum 1 after transfer
The surface a is cleaned of the residual toner particles by the cleaning means 6a, and is prepared for the subsequent image formation.

On the other hand, in synchronism with the formation of the black toner image, in parallel with this, at the image forming station Pb, the surface of the photosensitive drum 1b is uniformly charged by electrostatic charge by the charging means 2b, and then exposed. An electrostatic latent image corresponding to the image information of the cyan component is formed on the photosensitive drum 1b by the means 3C. This electrostatic latent image is developed by the developing means 4b.
Is developed on the photosensitive drum 1b as a powder image of cyan toner particles, and is superimposed on the black toner image formed on the intermediate transfer belt 7 to form a prototype toner image. Similarly, the image forming station Pc superimposes a magenta toner image, and the image forming station Pd superimposes a yellow toner image on each other.
Formed on top, a synthetic toner image is formed.

After the above-mentioned four color toner images have been superposed, the intermediate transfer belt 7 is brought into contact with the intermediate transfer belt 7 on the sheet material 9 such as paper fed from the paper feed cassette 10 by the paper feed roller 8. The synthetic toner image is transferred by the transfer roller 11 arranged at a position where the sheet material 9 is sandwiched between the belt 7 and the belt 7, and is heated and fixed by the fixing means 12 to form a color image on the sheet material 9. .

However, in the tandem engine type image forming apparatus as described above, when the temperature is unstable when the power is turned on, or when the image forming stations Pa, Pb, Pc,
The image forming stations Pa, Pb, P depending on the exchange of Pd, the setting status of the image forming apparatus, the temperature change in the apparatus, and the like.
Various color misregistrations as shown in FIGS. 2A to 2E occur due to misalignment of c, Pd, attachment of the scanning optical system, and the like.

In FIG. 2, (a) shows the intermediate transfer belt 7.
Sub-scanning position shift that is displaced in parallel by moving in the moving direction A of
(B) is a main scanning position shift displaced in parallel with the scanning direction of the exposing means 3 (direction perpendicular to the moving direction A of the intermediate transfer belt 7), and (c) is a scanning direction of the exposing means 3. A skew error in which the image is tilted and displaced, (d) is a magnification error in which the magnification in the scanning direction of the exposure unit 3 is displaced between the image forming stations Pa, Pb, Pc, and Pd, and (e) is a scanning direction in the exposure unit 3. Represents a bending error in which the image is bent.

The main cause of various color misregistrations is that the sub-scanning position misalignment (a) and the main scanning misalignment (b) are the misalignment of the image forming stations Pa, Pb, Pc, Pd and the exposure means 3, or the exposure. The skew error (c) is caused by the misalignment of the lenses and mirrors (not shown) constituting the scanning optical system of the means 3, and the skew error (c) is at each image forming station P.
a, Pb, Pc, Pd photosensitive drums 1a, 1b, 1
Misalignment of the mounting angles of the rotating shafts c and 1d and the exposure means 3
The error (d) in magnification is caused by the deviation of the mounting angle of the optical path length from the scanning optical system of each exposure unit 3K, 3C, 3M, 3Y to the surface of each photoconductor drum 1a, 1b, 1c, 1d. The bending error (e) is due to misalignment of the lenses and mirrors (not shown) that form the scanning optical system of each of the exposure units 3K, 3C, 3M, and 3Y.

Therefore, when the power is turned on, when each image station is replaced, or when the temperature inside the apparatus changes, a reference pattern (hereinafter referred to as "registration pattern") is marked on the intermediate transfer belt 7 in advance. Then, the registration pattern is detected by the color shift detection means 13 having a plurality of sensors, the five types of color shift amounts are calculated from the detection results, and the color shifts for matching the positions of the respective color images in accordance with the shift amounts. It is necessary to make a correction.

The color shift detection and color shift correction operations of the conventional color image forming apparatus will be described below with reference to the drawings.

FIG. 3 is a block diagram of a conventional color shift detector, FIG.
Is a layout diagram of the conventional registration pattern on the intermediate transfer belt and the positional deviation detection unit, and FIG. 5 is a layout diagram of the conventional registration pattern on the intermediate transfer belt and the color deviation detection unit and the output signals of the color deviation detection unit. FIG.

In FIG. 3, a color misregistration detecting means 13 for detecting misregistration of the registration pattern, which is arranged on the intermediate transfer belt 7, includes a light source 31 such as a lamp or a laser, and a sensor 33 for detecting the registration pattern. And a lens 32 for forming an image of the registration pattern irradiated on the light source 31 on the sensor 33.
Composed of and. As shown in FIG. 4, two color misregistration detecting means 13 are provided near the scanning start position and the scanning end position of the exposing means 3 on the line orthogonal to the moving direction A of the intermediate transfer belt 7 (color misregistration detecting means 13a and Color shift detection means 13
b) It is provided. The sensors of the color misregistration detection unit 13a and the color misregistration detection unit 13b are arranged on a line orthogonal to the moving direction A of the intermediate transfer belt 7.

In the above-described structure, in the color misregistration detection operation, a registration pattern such as a predetermined straight line or a figure as shown in FIG. The registration patterns 34, 35, 3 for each color are defined by a straight line including the scan start position and a straight line including the scan end position of the exposure unit 3 arranged on a line orthogonal to A at predetermined intervals.
6 and 37 are transferred onto the intermediate transfer belt 7, and the color shift detecting means 13a and the color shift detecting means 13b measure the positional shift amount (color shift amount) of each color.

Regarding the sub-scanning position shift shown in FIG. 2A, the registration patterns of the respective colors on the intermediate transfer belt 7 are color shift detecting means 13a as shown in FIG. 5A.
Time T1 passing through the sensor 33a in the inside and the time difference ΔT (ΔTn = T−Tn: n =
1, 2, 3, 4) and the moving speed V of the intermediate transfer belt 7
From the position deviation ΔYn (ΔYn = ΔTn × V: n
= 1, 2, 3, 4) is calculated.

Regarding the main scanning position shift shown in FIG. 2B, for example, by setting the registration pattern as an oblique line, the registration pattern is detected by the sensor 3 in the color shift detecting means 13a in the same manner as described above.
The positional deviation of each color is calculated from the time between the passing time 3a and a predetermined design value and the moving speed V of the intermediate transfer belt 7.

With respect to the skew error shown in FIG. 2C, the registration pattern of the same color on the intermediate transfer belt 7 has a color shift detecting means 13a as shown in FIG. 5B.
And a time difference ΔTTn (n = 1, 2 ,,) passing through the sensors 33a and 33b in the color shift detection means 13b.
3, 4) and the moving speed V of the intermediate transfer belt 7, the skew error ΔYYn (ΔYYn = ΔTTn × V:
n = 1, 2, 3, 4) is calculated.

As for the magnification error shown in FIG. 2D, the main scanning position deviation is calculated by the color deviation detecting means 13a and the color deviation detecting means 13b as described above, and the value and a predetermined design value are set. Magnification error is calculated from the difference.

The curvature error shown in FIG. 2 (e) cannot be accurately measured by the conventional color misregistration detection operation using two sensors. Therefore, the error is reduced by increasing the accuracy of assembling the lenses in the exposure unit 3.

Based on the four types of color shift amounts detected as described above, the color shift correction operation is performed.

FIG. 6 is a block diagram of a color misregistration correction mechanism of a scanning optical system in a conventional exposure means. In FIG. 6, the scanning optical system of the exposure means 3 arranged on the photosensitive drum 1 includes a polygon motor 61, a polygon mirror 62 attached to the shaft of the polygon motor 61, an adjusting actuator 66, and an adjusting actuator 67. And a pair of substantially C-shaped folding mirrors 63, 64 which are movable in the front-rear direction and whose mirror surfaces are held at a right angle, and finally scan the scanning light beam to the photosensitive drum 1.
And a folding mirror 65 for irradiating the light. The adjusting actuator 66 is a folding mirror 63,
64 is moved horizontally in the front-back direction (direction of arrow C in FIG. 6), and the adjustment actuator 67 moves the folding mirror 63,
64 is moved in the vertical direction (direction of arrow D in FIG. 6).
As an actuator for performing these adjustments, a linear step actuator having a step motor, which is a drive source that linearly moves in stages, is used. The image data is optically modulated by a semiconductor laser (not shown),
It is incident on the polygon mirror 62. Polygon mirror 62
The scanning light beam reflected by the folding mirrors 63, 64, 6
It is sequentially reflected at 5, and is irradiated onto the surface of the photosensitive drum 1. The irradiation position of the scanning light beam is controlled by a polygon motor 61, an adjusting actuator 66, and an adjusting actuator 67 which are independently driven.

With the scanning optical system configured as described above, the correction of the sub-scanning position deviation shown in FIG. 2A and the main scanning position deviation shown in FIG. 2B is started by the exposure means 3 for each color. Timing correction, phase control of scanning start timing signal, phase control of polygon motor, etc.
The skew error shown in FIG. 2C and the magnification error shown in FIG. 2D are corrected by adjusting the irradiation position and adjusting the optical path length by the adjusting actuator 66 and the adjusting actuator 67.

[0027]

However, in the above-mentioned conventional configuration, when the registration pattern for checking the amount of color misregistration is transferred onto the intermediate transfer belt as a toner image, the eccentricity of the drive portion of the intermediate transfer belt or The toner image is transferred onto the intermediate transfer belt because the part where the toner image is transferred on the intermediate transfer belt does not move at a constant speed (zero acceleration) due to axial deviation of the drive unit or waviness of the intermediate transfer belt. The transfer position is not constant and is shifted, and as a result, the registration pattern vibrates. In addition, the toner image itself may not be accurately formed on the image forming unit due to eccentricity of the driving unit of the image forming unit or axial deviation of the driving unit. As a result, if the registration pattern is used to detect the amount of color misregistration, an amount of color misregistration that is different from the actual amount will be detected, and as a result, correction cannot be performed with high accuracy, or conversely, the amount of color misregistration will be increased. However, there is a problem in that the print quality deteriorates.

The present invention has been made in order to solve this problem. By drawing the registration pattern with high accuracy, the color misregistration can be corrected more accurately and an image of high print quality can be obtained. It is to provide a color image forming apparatus capable of performing the same.

[0029]

In order to solve the above-mentioned problems, a color image forming apparatus of the present invention comprises an image carrying means for carrying and carrying an image on the surface, and an image according to image information of each color. A plurality of image forming means formed for each color formed above, and a registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during a color misregistration detection operation. A color shift detecting means for detecting color shift of an image from the registration pattern, and an image forming unevenness detecting means for detecting image forming unevenness in a plurality of image forming means installed for each color. .

With this configuration, when the registration pattern is formed, the registration pattern is formed at the time when the composite image forming unevenness of the image forming means is the smallest, so that the resist showing a more accurate color shift amount can be obtained. It is possible to form a coloration pattern, and the accuracy of color misregistration correction is improved, so that it is possible to provide a color image forming apparatus that can obtain an image with high print quality.

In order to solve the above problems, the color image forming apparatus forms an image carrying means for carrying an image on the surface and carrying it and an image according to the image information of each color on the image carrying means. A plurality of image forming means installed for each color; a registration pattern generating means for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color misregistration detection operation; The color misregistration detecting means for detecting the color misregistration of the image from the image formation pattern, and the image formation unevenness detecting means for detecting the image formation unevenness in the plurality of image forming means installed for each color.

With this configuration, when the registration pattern is formed, it is possible to form the registration pattern of each color at the time when the unevenness of image formation of each of the image forming means is the smallest, and thus, the registration pattern of each color is more accurate. Since it is possible to form a registration pattern that represents the amount of color misregistration and the accuracy of color misregistration correction is improved, it is possible to provide a color image forming apparatus that can obtain an image with high print quality.

In order to solve the above problems, the color image forming apparatus forms an image carrying means for carrying an image on the surface and carrying it and an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each color; a registration pattern generating means for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color misregistration detection operation; Color misregistration detection means for detecting the color misregistration of the image from the image formation pattern, image formation irregularity cycle detection means for measuring the cycle of each of the plurality of image forming means installed for each color, and the plurality of measured image formation means Of the respective periods, the phase matching means for matching the phases is provided.

With this configuration, when the registration pattern is formed, it is possible to form the registration pattern at the time when the unevenness of image formation is minimized in the state where the phases of the cycles of the plurality of image forming units are matched. As a result, it is possible to form a registration pattern that represents a more accurate color misregistration amount, and the accuracy of color misregistration correction improves, thereby providing a color image forming apparatus that can obtain an image with high print quality. can do.

In order to solve the above-mentioned problems, the color image forming apparatus forms an image carrying means for carrying an image on the surface and carrying it and an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each color; a registration pattern generating means for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color misregistration detection operation; Color misregistration detecting means for detecting the color misregistration of the image from the image formation pattern, the image forming unevenness detecting means for detecting the image forming unevenness in the plurality of image forming means installed for each color, and the unevenness of the conveyance of the image conveying means. The transport unevenness detecting means is provided.

With this configuration, when the registration pattern is formed, it is possible to form the registration pattern at the time when the unevenness of the image carrying means and the unevenness of the combined image forming of the image forming means are the smallest. By this, it becomes possible to form a registration pattern representing a more accurate amount of color misregistration, and by improving the accuracy of color misregistration correction, a color image forming apparatus capable of obtaining an image with high print quality is provided. be able to.

In order to solve the above problems, the color image forming apparatus forms an image carrying means for carrying an image on the surface and carrying it and an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each color; a registration pattern generating means for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color misregistration detection operation; Color misregistration detecting means for detecting the color misregistration of the image from the image formation pattern, the image forming nonuniformity detecting means for detecting the image forming nonuniformity in the plurality of image forming means installed for each color, and the nonuniformity of conveyance of the image conveying means. It is configured to include a conveyance unevenness detection unit.

With this configuration, when the registration pattern is formed, the registration for each color is performed at the time when there is little unevenness in conveyance, and at the time when there is the least unevenness in image formation for each of the plurality of image forming units installed for each color. It is possible to form a registration pattern, which makes it possible to form a registration pattern that represents a more accurate amount of color misregistration, and improves the accuracy of color misregistration correction to obtain an image with high print quality. It is possible to provide a color image forming apparatus capable of performing the above.

In order to solve the above-mentioned problems, the color image forming apparatus forms an image carrying means for carrying and carrying an image on the surface and an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each color; a registration pattern generating means for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color misregistration detection operation; Color misregistration detection means for detecting the color misregistration of the image from the image formation pattern, image formation irregularity cycle detection means for measuring the cycle of each of the plurality of image forming means installed for each color, and the plurality of measured image formation means The phase adjusting means for adjusting the phases of the respective cycles and the uneven conveyance detecting means for detecting uneven conveyance of the image conveying means are provided.

With this configuration, when the registration pattern is formed, registration unevenness is minimized in the state where the phases of the cycles of the plurality of image forming units are matched, and at the time when the unevenness of image formation is the smallest. It becomes possible to form a pattern, which makes it possible to form a registration pattern that represents a more accurate amount of color misregistration, and the accuracy of color misregistration correction improves, so that an image with high print quality can be obtained. It is possible to provide a color image forming apparatus that can be used.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A color image forming apparatus according to claim 1 of the present invention is an image carrying means for carrying and carrying an image on the surface, and an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each color, and a registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during a color misregistration detection operation. A color shift detecting means for detecting a color shift of an image from the registration pattern, and an image forming unevenness detecting means for detecting image forming unevenness in a plurality of image forming means installed for each color. With this configuration, it is possible to form a registration pattern at the time when there is the least amount of image formation unevenness in the combined image forming means. Ri, the effect of drawing shake registration pattern is reduced, the registration pattern is more accurately rendered, an effect that measurement of the color shift amount becomes high accuracy.

A color image forming apparatus according to a second aspect of the present invention is an image carrying means for carrying and carrying an image on the surface, and each color for forming an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each,
Registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during color shift detection operation, and color shift detection for detecting image color shift from the registration pattern And an image forming unevenness detecting unit for detecting image forming unevenness in a plurality of image forming units installed for each color. With this configuration, a plurality of image forming units installed for each color are provided. By forming the registration pattern for each color at the time when the image forming unevenness of each means is the smallest, the influence of the drawing blur of the registration pattern is reduced, the registration pattern is drawn more accurately, and the amount of color misregistration Has the effect of making the measurement of high precision.

According to a third aspect of the present invention, there is provided a color image forming apparatus in which an image carrying means for carrying an image on the surface and carrying it and each color for forming an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each,
Registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during color shift detection operation, and color shift detection for detecting image color shift from the registration pattern Means, an image formation unevenness cycle detection means for measuring the cycle of each of the plurality of image forming means installed for each color, and a phase adjusting means for matching the phase of each cycle of the measured plurality of image forming means With this configuration, in the state where the phases of the cycles of the plurality of image forming units are aligned, the registration pattern is formed by forming the registration pattern at the time when the image formation unevenness is the smallest. The effect of image blurring is reduced and the registration pattern becomes more accurate. It is drawn in, with the effect that measurement of the color shift amount becomes high accuracy.

A color image forming apparatus according to a fourth aspect of the present invention is an image carrying means for carrying and carrying an image on the surface and each color for forming an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each,
Registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during color shift detection operation, and color shift detection for detecting image color shift from the registration pattern Means, and an image forming unevenness detecting means for detecting image forming unevenness in a plurality of image forming means installed for each color, and a carrying unevenness detecting means for detecting carrying unevenness of the image carrying means, With this configuration, the registration pattern is formed at the time when the conveyance unevenness of the image conveying unit and the combined image formation unevenness of the image forming unit are minimized, so that the influence of the drawing blurring of the registration pattern is reduced, and the registration pattern is reduced. The pattern is drawn more accurately, and the amount of color shift is measured. It has the effect that it becomes highly accurate.

A color image forming apparatus according to a fifth aspect of the present invention is an image carrying means for carrying and carrying an image on the surface, and each color for forming an image according to image information of each color on the image carrying means. A plurality of image forming means installed for each,
Registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during color shift detection operation, and color shift detection for detecting image color shift from the registration pattern Means, and an image forming unevenness detecting means for detecting image forming unevenness in a plurality of image forming means installed for each color, and a carrying unevenness detecting means for detecting carrying unevenness of the image carrying means, With this configuration, the registration pattern is formed for each color at the time when there is little unevenness in conveyance, and at the time when the unevenness in image formation of each of the plurality of image forming means installed for each color is the smallest. The effect of image blurring on the Ri is accurately rendered, an effect that measurement of the color shift amount becomes high accuracy.

According to a sixth aspect of the present invention, there is provided a color image forming apparatus which carries an image on the surface thereof and conveys the image, and each color which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means installed for each,
Registration pattern generating means for performing control to form a registration pattern for each color on the image conveying means by the image forming means during color shift detection operation, and color shift detection for detecting image color shift from the registration pattern Means, an image forming unevenness cycle detecting means for measuring each cycle of a plurality of image forming means installed for each color, and a phase adjusting means and an image for matching the phases of the measured cycles of a plurality of image forming means The present invention is provided with a conveyance unevenness detection unit for detecting the conveyance unevenness of the conveyance unit. With this configuration, the conveyance unevenness is small in the state where the phases of the cycles of the plurality of image forming units are matched, and the image By forming the registration pattern at the time of the least unevenness of formation,
This has an effect that the influence of the drawing blurring of the registration pattern is reduced, the registration pattern is drawn more accurately, and the measurement of the color misregistration amount becomes highly accurate.

(Embodiment 1) FIG. 7 is a functional block diagram of a color image forming apparatus in Embodiments 1 and 2 of the present invention, and FIG. 11 is an image in a plurality of image forming means in Embodiment 1 of the present invention. 6 is a graph showing the irregularity of formation and the period of the combined irregularity of image formation in time series.

The image forming unit of the color image forming apparatus according to the present embodiment has the same device configuration as the conventional configuration shown in FIG. 1, and a description thereof will be omitted.

In FIG. 7, 71a, 71b, 71c,
71d is a pattern for measuring unevenness in conveyance, which is formed at equal intervals by an encoder or the like (not shown) attached to the drive unit of the image forming unit for each color, or by the same procedure as the registration pattern formation. An image forming unevenness detecting means 72 for measuring the image forming unevenness of the image forming means by a means such as forming on the intermediate transfer belt 7 and detecting by the same procedure as the color shift detecting means 13, and 72 an image forming unevenness detecting means. 71a, 71b, 7
1c and 71d, a registration pattern generating means for generating a registration pattern using the cycle of image formation unevenness detected, 3 is the exposing means, P
a, Pb, Pc, and Pd are the image stations, and 7 is
The intermediate transfer belt 13 which is an image conveying means, the color shift detecting means 73, and the color shift detecting means 73 correspond to the color shifts detected by the color shift detecting means 13 as shown in FIGS. Color misregistration correction means for performing color misregistration correction.

The color misregistration detecting means 13 has the same structure as the conventional structure shown in FIG. 3, and the description of its structure and operation will be omitted.

The color misregistration correction means 73 has the same structure as the conventional structure as shown in FIG. 6, and the description of its structure and operation will be omitted.

In FIGS. 11A to 11D, the vertical axis represents the amount of image formation unevenness in the image forming means for each color, and the horizontal axis represents time. Ta, Tb, Tc, and Td represent the cycle of each image formation unevenness. Each image formation unevenness is a cycle depending on the cycle of each component (gear, pulley, etc.) in the image forming means. This cycle may use a known design value, or if there is no design value, it can be obtained by a method such as frequency analysis of the output of an encoder (not shown) attached to the drive unit of each image forming unit. You can These image formation irregularities are mainly a vibration system and have periodicity, and the amount of image formation irregularities does not diverge. Therefore, when viewed in time series, there are always times Xa, Xb, Xc, and Xd where the amount of image formation unevenness is small. Even at the time when the amount of the image formation unevenness is small, it can be obtained in the same manner as the method for obtaining the cycle. In FIG. 11 (e), the vertical axis represents the difference between FIGS. 11 (a) to 11 (d), and the horizontal axis represents time. As shown in (e) of FIG. 11, when the image forming unevenness in the image forming means of each color has a cycle, the image forming unevenness of four colors, which is a composite of the image forming unevenness, also has a cycle. It can be determined from the image formation unevenness in the forming means. The image forming unevenness that is a composite of the image forming unevennesses also has a periodicity and does not diverge, so that the areas Y1, Y2, Y where the amount of image forming unevenness is small.
3 and Y4 are present. Therefore, this Y1, Y2, Y3,
By forming the registration pattern at the location of Y4, it is possible to form a more accurate registration pattern that is less affected by unevenness in image formation, and as a result, it is possible to detect the amount of color misregistration and correct the color misregistration. Becomes

(Embodiment 2) FIG. 7 is a functional block diagram of a color image forming apparatus in Embodiments 1 and 2 of the present invention, and FIG. 11 is an image in a plurality of image forming means in Embodiment 1 of the present invention. It is the graph which represented the period of formation unevenness on the time series. Since these are the same as those in the first embodiment, description of the configuration and operation thereof will be omitted.

In the first embodiment, the registration pattern is formed at the time when the amount of combined image formation unevenness is small. To this end, the combined image formation unevenness is caused by the image formation unevenness of each image forming means. Is required. Therefore, the registration pattern is not formed at the time when the amount of combined image formation unevenness is small, but the registration for each color is performed for each image forming unit at the time Xa, Xb, Xc, and Xd where the image formation unevenness is small. Form a ration pattern. This eliminates the need for the processing to obtain the composite image formation unevenness, and enables the formation of a more accurate registration pattern that is less affected by each image formation unevenness. As a result, highly accurate color misregistration amount detection and color misregistration can be performed. Correction is possible.

(Third Embodiment) FIG. 8 is a functional block diagram of a color image forming apparatus according to a third embodiment of the present invention.
FIG. 12 is a time-series graph showing the period of image formation unevenness in a plurality of image forming means and the combined image formation unevenness in the third embodiment of the present invention.

In FIG. 8, reference numeral 81 denotes an uneven image forming phase adjusting means for adjusting the phases of the uneven image forming periods in the respective image forming means. Others are the same as those in the first embodiment, and therefore the description of the configuration and operation thereof will be omitted.

In FIGS. 12A to 12F, the vertical axis represents the amount of image formation unevenness in the image forming means for each color, and the horizontal axis represents time. Here, for the sake of simplicity, a case where the image forming unevenness periods of the respective image forming means are the same will be described for the case of two colors. 12A and 12B show image formation unevenness in image forming means of different colors. They have the same period but are out of phase by Z. In this case, the difference between FIG. 12A and FIG.
The color shift becomes large as shown in FIG. 12D and 12E show image formation unevenness in image forming means of different colors. They have the same period but are not out of phase. In this case, FIG.
The difference between (d) and FIG. 12 (e), that is, the difference between the two colors is
It becomes small as shown in FIG. in this way,
If the period is the same, the difference will be only the difference in amplitude if the phase is the same, and will be large if the phases are out of phase. Therefore, first, the phase of each image forming unit is obtained by frequency analysis or the like, and the respective phases are matched. After that, as shown in the first embodiment, a registration pattern is formed at a time when there is little drawing unevenness, thereby forming a more accurate registration pattern that is less affected by image forming unevenness than the method of the first embodiment. As a result, highly accurate color misregistration amount detection and color misregistration correction can be performed.

(Fourth Embodiment) FIG. 9 is a functional block diagram of a color image forming apparatus according to the fourth and fifth embodiments of the present invention. FIG. 11 is a graph showing the cycle of image formation unevenness in the plurality of image forming means in the first embodiment of the present invention in time series. These are the first embodiment
Since it is the same as the above, the description of its configuration and operation will be omitted.

In FIG. 9, reference numeral 91 is an intermediate transfer belt conveyance unevenness detecting means for detecting the conveyance unevenness on the intermediate transfer belt which is a conveying means. Reference numeral 72 denotes registration using the cycle of image formation unevenness detected by the image formation unevenness detection means 71a, 71b, 71c, 71d and the conveyance unevenness cycle detected by the intermediate transfer belt conveyance unevenness detection means 91. It is a registration pattern generating means for generating a pattern. Others are the same as those in the first embodiment, and therefore the description of the configuration and operation thereof will be omitted.

Like the image forming unevenness described in the first embodiment, the uneven transportation occurs in a cycle depending on the cycle of each component (gear, pulley, etc.) in the intermediate transfer belt. This cycle may use a known design value,
If there is no design value, the output of an encoder (not shown) attached to the drive unit of the intermediate transfer belt can be obtained by a method such as frequency analysis. These transport irregularities are
It is mainly an oscillating system and has periodicity and does not diverge the amount of uneven transport. Therefore, when viewed in a time series, there is always a time point (not shown) at which the amount of uneven transport is small, as in the uneven image formation described in the first embodiment. Even at the time when the amount of uneven transportation is small, it can be obtained in the same manner as the method for obtaining the cycle. The transport irregularities can be considered in the same manner as the image irregularities described in the first embodiment. Therefore, by forming the registration pattern at the time when the image formation unevenness that is a composite of the image formation unevennesses described in the first embodiment is small, and at the time when the conveyance unevenness is small, the effect of the uneven conveyance in the first embodiment is reduced. It is possible to form a small number of registration patterns, that is, a registration pattern that is more accurate than that of the first embodiment, and as a result, it is possible to detect the color misregistration amount and correct the color misregistration with higher accuracy.

(Fifth Embodiment) FIG. 9 is a functional block diagram of a color image forming apparatus according to the fourth and fifth embodiments of the present invention. FIG. 11 is a graph showing the cycle of image formation unevenness in the plurality of image forming means in the first embodiment of the present invention in time series. These are the first embodiment
Since it is the same as that of No. 2 and 2, the description of the configuration and operation thereof will be omitted.

The uneven transport can be considered in the same manner as the uneven image formation, as described in the fourth embodiment.
Therefore, for each image forming unit shown in the second embodiment,
A registration pattern for each color is formed at the time points Xa, Xb, Xc, and Xd where there is little image formation unevenness, and at the time points when there is little carry unevenness. This eliminates the need for the process for obtaining the composite image formation unevenness, and the registration unevenness is less affected by the conveyance unevenness than in the second embodiment, that is, the registration pattern can be formed more accurately than in the second embodiment. Therefore, it is possible to detect the color shift amount and correct the color shift with higher accuracy.

(Embodiment 6) FIG. 10 is a functional block diagram of a color image forming apparatus according to Embodiment 6 of the present invention, and FIG. 12 is image formation unevenness in a plurality of image forming means according to Embodiment 3 of the present invention. 6 is a graph showing the cycle of the image formation unevenness and the combined image formation time series. Since these are the same as those in the third and fourth embodiments, the description of the configuration and operation thereof will be omitted.

The unevenness of conveyance can be considered in the same manner as the unevenness of image formation, as described in the fourth embodiment.
Therefore, the phase of each image forming unit shown in the third embodiment is obtained by frequency analysis or the like, and the respective phases are matched to form a registration pattern at the time when the drawing unevenness is small and the transfer unevenness is small. The effect of transport unevenness is smaller than that of the third embodiment, that is, a registration pattern that is more accurate than that of the third embodiment can be formed, and as a result, more accurate color misregistration amount detection and color misregistration correction are possible. Becomes

[0065]

As described above, according to the color image forming apparatus of the first aspect of the present invention, the image carrying means for carrying and carrying the image on the surface, and the image corresponding to the image information of each color are provided. A plurality of image forming means installed for each color formed on the image carrying means, and registration for performing control for forming a registration pattern for each color on the image carrying means by the image forming means during a color shift detection operation. By providing the pattern generating means, the color misregistration detecting means for detecting the color misregistration of the image from the registration pattern, and the transport unevenness detecting means for detecting the transport unevenness in the image transporting means, the registration is performed at the time when the transport unevenness is small. The registration pattern can be transferred, and the influence of the blurring of the registration pattern is reduced, It is possible to provide a color image forming apparatus capable of obtaining an image with high print quality by accurately drawing the coloration pattern and measuring the color misregistration amount with high accuracy. can get.

According to the color image forming apparatus of the second aspect of the present invention, the image carrying means for carrying and carrying the image on the surface, and the image according to the image information of each color are formed on the image carrying means. A plurality of image forming means installed for each color, registration pattern generating means for performing control for forming a registration pattern for each color on the image conveying means by the image forming means during a color shift detection operation, and By providing the color misregistration detection means for detecting the color misregistration of the image from the registration pattern and the image formation unevenness cycle detection means for each of the plurality of image forming means installed for each color, the plurality of color misalignment detection means installed for each color At the time when the image forming unevenness of each of the image forming means
The registration pattern can be transferred, the influence of the registration pattern blurring is reduced, the registration pattern is drawn more accurately, and the amount of color misregistration is measured with high accuracy, resulting in an image with high print quality. The advantageous effect that it is possible to provide a color image forming apparatus capable of obtaining the above is obtained.

A color image forming apparatus according to a third aspect of the present invention is the color image forming apparatus according to the second aspect, wherein the measured phases of the respective periods of the plurality of image forming means are matched. By providing the means, it is possible to transfer the registration pattern in the state where the phases of the respective cycles of the plurality of image forming means are matched, and the influence of the drawing blurring of the registration pattern of each color becomes the same. Since the measurement of the deviation amount becomes highly accurate, there is an advantageous effect that it is possible to provide a color image forming apparatus capable of obtaining an image with high print quality.

According to the color image forming apparatus of the fourth aspect of the present invention, the image carrying means for carrying and carrying the image on the surface, and the image according to the image information of each color are formed on the image carrying means. A plurality of image forming means installed for each color, registration pattern generating means for performing control for forming a registration pattern for each color on the image conveying means by the image forming means during a color shift detection operation, and Color misregistration detection means for detecting color misregistration of an image from a registration pattern, conveyance unevenness detection means for detecting unevenness of conveyance in the image conveyance means, and image formation unevenness cycle of each of a plurality of image forming means installed for each color. Since the detection means is provided, at the time when the unevenness in the conveyance of the image conveying means and the unevenness in the combined image formation of the image forming means are the smallest, Installation patterns can be transferred, the influence of registration pattern blurring can be reduced, registration patterns can be drawn more accurately, and the amount of color misregistration can be measured with high accuracy, resulting in images with high print quality. The advantageous effect that it is possible to provide a color image forming apparatus capable of obtaining the above is obtained.

According to a fifth aspect of the present invention, there is provided a color image forming apparatus according to the fourth aspect, wherein the plurality of color image forming apparatuses are installed at each time when there is little unevenness in conveyance. The registration pattern can be transferred at the time when the unevenness of image formation of each of the image forming means is the smallest, the influence of the drawing blur of the registration pattern is reduced, the registration pattern is drawn more accurately, and the amount of color misregistration With the high accuracy of the measurement of 1, it is possible to provide an advantageous effect that it is possible to provide a color image forming apparatus that can obtain an image with high printing quality.

According to the color image forming apparatus of the sixth aspect of the present invention, the image carrying means for carrying and carrying the image on the surface, and the image according to the image information of each color are formed on the image carrying means. A plurality of image forming means installed for each color, registration pattern generating means for performing control for forming a registration pattern for each color on the image conveying means by the image forming means during a color shift detection operation, and Color misregistration detection means for detecting color misregistration of an image from a registration pattern, conveyance unevenness detection means for detecting unevenness of conveyance in the image conveyance means, and image formation unevenness cycle of each of a plurality of image forming means installed for each color. By providing the detection means, there is little conveyance unevenness in the state where the phases of the cycles of the plurality of image forming means are matched, and In the most less the time of forming the village,
The registration pattern can be transferred, the influence of the registration pattern blurring is reduced, the registration pattern is drawn more accurately, and the amount of color misregistration is measured with high accuracy, resulting in an image with high print quality. The advantageous effect that it is possible to provide a color image forming apparatus capable of obtaining the above is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional color image forming apparatus.

FIG. 2 is a diagram showing types of color misregistration in a general color image forming apparatus.

FIG. 3 is a configuration diagram of a conventional color shift detection unit.

FIG. 4 is a layout diagram of a registration pattern and a positional deviation detection unit on a conventional intermediate transfer belt.

FIG. 5 is a diagram showing a layout pattern of a registration pattern on a conventional intermediate transfer belt, a position shift detection unit, and an output signal of the color shift detection unit.

FIG. 6 is a configuration diagram of a color misregistration correction mechanism of a scanning optical system in a conventional exposure unit.

FIG. 7 is a functional block diagram of the color image forming apparatus according to the first and second embodiments of the present invention.

FIG. 8 is a functional block diagram of a color image forming apparatus according to a third embodiment of the present invention.

FIG. 9 is a functional block diagram of a color image forming apparatus according to Embodiments 4 and 5 of the present invention.

FIG. 10 is a functional block diagram of a color image forming apparatus according to a sixth embodiment of the present invention.

FIG. 11 is a graph showing, in a time series, the period of image formation unevenness in a plurality of image forming means and the combined image formation unevenness in the first embodiment of the present invention.

FIG. 12 is a graph showing, in a time series, the period of image formation unevenness in a plurality of image forming means and the combined image formation unevenness in the third embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1b, 1c, 1d Photosensitive drums 2a, 2b, 2c, 2d Charging means 3, 3K, 3C, 3M, 3Y Exposure means 4a, 4b, 4c, 4d Developing means 5a, 5b, 5c, 5d Transfer means 6a, 6b, 6c, 6d Cleaning means 7 Intermediate transfer belt 8 Paper feeding roller 9 Sheet material 10 Paper feeding cassette 11 Transfer roller 12 Fixing means 13 Color misregistration detecting means 14a, 14b Driving roller 31 Light source 32 Lens 33 Sensor 34 to 37 Registration Registration pattern 61 polygon motor 62 polygon mirrors 63, 64, 65 folding mirrors 66, 67 adjustment actuators 71a, 71b, 71c, 71d image formation unevenness detection means 72 registration generation means 73 color misregistration correction means 81 image formation unevenness phase adjustment means 91 Intermediate Transfer Belt Conveyance Unevenness Detection Unit P , Pb, Pc, Pd Image forming stations Ta, Tb, Tc, Td, Te, Tf Image formation unevenness periods Xa, Xb, Xc, Xd Times with less image formation unevenness Y1, Y2, Y3, Y4 Combined image formation unevenness Phase difference of image formation unevenness Z

Claims (6)

(57) [Claims] 1. An image carrying means for carrying and carrying an image on the surface, a plurality of image forming means provided for each color for forming an image on the image carrying means according to image information of each color, and a color. Registration pattern generating means for performing control to form a registration pattern for each color on the image carrying means by the image forming means during a shift detecting operation, and color shift detecting means for detecting a color shift of an image from the registration pattern A color image forming apparatus including: an image forming unevenness detecting unit that detects image forming unevenness in a plurality of image forming units installed for each color; A registration pattern generating unit that forms the registration pattern at the time when the unevenness is the least is provided. Color image forming apparatus according to symptoms. 2. The registration pattern generating means includes image forming unevenness cycle detecting means for each of the plurality of image forming means installed for each color, and each image for each of the plurality of image forming means installed for each color. The color image forming apparatus according to claim 1, wherein the registration pattern for each color is formed at the time when the formation unevenness is the smallest. 3. An image forming unevenness cycle detecting means for measuring the cycle of each of the plurality of image forming means installed for each color, and a phase adjusting means for matching the phase of each cycle of the measured plurality of image forming means. 7. The registration pattern generating means forms the registration pattern at a time when the unevenness of image formation is minimized in a state where the phases of the cycles of the plurality of image forming means are matched. 1. The color image forming apparatus described in 1. 4. A registration unevenness detection unit for detecting unevenness of the transfer of the image transfer unit, wherein the registration is performed at a time point when the transfer unevenness of the image transfer unit and the image formation unevenness of the combined image forming unit are the smallest. The color image forming apparatus according to claim 1, wherein a pattern is formed. 5. A conveyance unevenness detecting means for detecting the unevenness of conveyance of the image conveying means is provided, and the registration pattern generating means includes a plurality of image forming means installed at each time when the unevenness of conveyance is small. 3. The color image forming apparatus according to claim 2, wherein a registration pattern for each color is formed at the time when the unevenness of image formation is minimized. 6. An uneven transport detecting means for detecting uneven transport of the image carrying means, wherein the unevenness of carrying is small in the registration pattern generating means in a state where phases of respective cycles of the plurality of image forming means are matched. The registration pattern is formed at a time when the unevenness of image formation is minimized.
The described color image forming apparatus.