JP2000181171A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of color drift correction and to obtain images having high printing quality by forming registration patterns at the point of the time when the compounded image formation unevenness of image forming means is lest, thereby making it possible to form the registration patterns indicating an exacter color drift quantity. SOLUTION: Image formation unevenness detecting means 71a to 71d form patterns on an intermediate transfer belt 7 and measures the image formation unevenness of the image forming means. An image formation unevenness phase matching means 81 matches the phases of the image formation unevenness periods of the respective image forming means. An intermediate transfer belt transportation unevenness detecting means 91 detects the transportation unevenness of the intermediate transfer belt 7. The phases of the respective image forming means are determined by frequency analyses, etc., and the respective phases are matched. The registration patterns are formed at the point of the time when the plotting unevenness is less and at the point of the time when the transportation unevenness is less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color image forming apparatus provided with a color misregistration detecting mechanism in a registration mechanism of a tandem engine type color image forming apparatus, and a color misregistration detecting method of the color image forming apparatus.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus, 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 to light in accordance with image information. To discharge only the charge of the irradiated portion to the photosensitive drum substrate, thereby forming an image (electrostatic latent image) based on the distribution of the resulting electrostatic charge, and developing the electrostatic latent image with colored charged particles (toner particles). After forming a powder image of toner particles by toner development to form a powder image, transferring the powder image to a sheet material or the like, applying heat and other energy to fix the image by fusing. Forming is being done.

On the other hand, with the colorization of images, a plurality of independent images are formed on the respective photosensitive drums by forming the respective color powder images of a cyan image, a magenta image, a yellow image, and more preferably a black image by the toner phenomenon. A tandem engine type color image forming apparatus that includes a forming station and superimposes and transfers and synthesizes a powder image formed on each photoconductor drum on an intermediate transfer material at a transfer position of each color powder image has also been proposed. I have. In the tandem engine type color image forming apparatus, since image formation is performed in parallel for each color, there is an advantage that the speed of image formation can be increased.

However, in the case of a tandem engine type color image forming apparatus, each powder image formed in a different image forming station is displaced due to a positional error or a timing deviation between the image forming stations, resulting in various colors. A shift occurs. In order to produce a high-quality color image forming apparatus, such a color shift becomes a very serious problem, and 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 such that four image forming stations Pa, Pb, Pc, and Pd are arranged side by side while being brought into contact with an upper portion of an intermediate transfer belt 7 rotated by driving rollers 14a and 14b. Each of the image forming stations has a photosensitive drum 1a, 1b, 1c, or 1d that comes 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 and 1d, charging means 2a, 2b, 2c and 2d for applying an electrostatic charge to each photosensitive drum are provided. Image forming stations Pa, Pb, Pc,
An exposure unit 3 which is a scanning optical system for exposing light corresponding to image information to each of the photosensitive drums 1a, 1b, 1c and 1d charged by the charging unit to form an electrostatic latent image is disposed above Pd. Has been established. Further, each photosensitive drum 1a, 1b, 1
developing means 4 for developing the electrostatic latent image formed by exposure with colored toner particles to form a powder image around c and 1d
a, 4b, 4c, 4d, developing means 4a, 4b, 4c, 4
transfer means 5 for superimposing and synthesizing each powder image formed in d on the intermediate transfer belt 7 at the transfer position of each color powder image
a, 5b, 5c, 5d, transfer means 5a, 5b, 5c, 5
d, cleaning means 6a, 6b, 6c, 6 for cleaning the surfaces of the photosensitive drums 1a, 1b, 1c, 1d after the respective powder images are transferred onto the intermediate transfer belt 7.
d are provided respectively.

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

Next, the image forming operation of the above-described conventional color image forming apparatus will be described. First, at the image forming station Pa, the surface of the photosensitive drum 1a is uniformly charged with electrostatic charge by the charging means 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 means 3K. Is formed. This electrostatic latent image is developed on the photoreceptor drum 1a as a powder image by black toner particles by the developing means 4a, and the powder image is transferred as a black toner image onto the intermediate transfer belt 7 by the transfer means 5a. You. Photoreceptor drum 1 after transfer
On the surface a, the residual toner particles are removed by the cleaning unit 6a, and the surface a is prepared for the next image formation.

On the other hand, in parallel with the formation of the black toner image, the surface of the photosensitive drum 1b is uniformly charged with electrostatic charges by the charging means 2b in the image forming station Pb. 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 unit 4b.
As a result, the toner image is developed on the photosensitive drum 1 b 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 draft toner image. Similarly, the magenta toner image is superimposed by the image forming station Pc and the yellow toner image is superimposed by the image forming station Pd.
And a composite toner image is formed thereon.

After the above-described superposition of the four color toner images is completed, the intermediate transfer belt 7 is brought into contact with the intermediate transfer belt 7 on the sheet material 9 such as the paper supplied from the paper supply cassette 10 by the paper supply roller 8. The composite toner image is transferred by a transfer roller 11 disposed at a position where the sheet material 9 is interposed between the belt 7 and the transfer roller 11, and is heated and fixed by a fixing unit 12 to form a color image on the sheet material 9. .

However, in the above-described tandem engine type image forming apparatus, when the temperature at the time of turning on the power is unstable, or when the image forming stations Pa, Pb, Pc,
Each image forming station Pa, Pb, P due to exchange of Pd, setting status of the image forming apparatus, temperature change in the apparatus, etc.
Various color shifts as shown in FIGS. 2A to 2E occur due to c, Pd, misalignment of the scanning optical system, and the like.

FIG. 2A shows an intermediate transfer belt 7.
Sub-scanning position shift due to parallel movement in the movement direction A of
(B) is a main scanning position shift that is shifted in parallel in the scanning direction of the exposure unit 3 (a direction perpendicular to the moving direction A of the intermediate transfer belt 7), and (c) is a deviation from the scanning direction of the exposure unit 3. A skew error in which the image is inclined obliquely, (d) is a magnification error in which the magnification of the exposure unit 3 in the scanning direction is shifted among the image forming stations Pa, Pb, Pc, and Pd, and (e) is a scanning direction of the exposure unit 3. Represents a curvature error in which the image is curved.

The main causes of various color misregistrations are the sub-scanning misalignment (a) and the main scanning misalignment (b) due to the misalignment of each image forming station Pa, Pb, Pc, Pd and the exposure means 3, or the exposure The skew error (c) is caused by misalignment of a lens or a mirror (not shown) that constitutes the scanning optical system of the means 3.
a, Pb, Pc, Pd photosensitive drums 1a, 1b, 1
c, deviation of the mounting angles of the rotating shafts 1d and the exposure means 3
The magnification error (d) is an error in the optical path length from the scanning optical system of each of the exposure units 3K, 3C, 3M, and 3Y to the surface of each of the photosensitive drums 1a, 1b, 1c, and 1d. The curvature error (e) is caused by misalignment of a lens or a mirror (not shown) constituting a 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 a "registration pattern") is marked on the intermediate transfer belt 7 in advance. The registration pattern is detected by the color misregistration detecting means 13 using a plurality of sensors, the five types of color misregistration amounts are calculated from the detection results, and the color misregistration for adjusting the position of each color image according to the misregistration amount It is necessary to make corrections.

The operation of detecting and correcting a color shift of a conventional color image forming apparatus will now be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional color misregistration detection unit, and FIG.
FIG. 5 is a layout diagram of a conventional registration pattern on the intermediate transfer belt and a misregistration detection unit. FIG. FIG.

In FIG. 3, a color shift detecting means 13 disposed above the intermediate transfer belt 7 for detecting a positional shift of a registration pattern 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.
It is composed of As shown in FIG. 4, the color misregistration detecting means 13 includes two color misalignment detecting means 13 near a scanning start position and a scanning ending position of the exposing means 3 on a line orthogonal to the moving direction A of the intermediate transfer belt 7. Color shift detecting means 13
b) It is provided. The sensors of the color shift detecting unit 13a and the color shift detecting unit 13b are arranged on a line orthogonal to the moving direction A of the intermediate transfer belt 7.

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

With respect to the sub-scanning position shift shown in FIG. 2A, as shown in FIG. 5A, the registration pattern of each color on the intermediate transfer belt 7 is detected by the color shift detecting means 13a.
, A time difference ΔT between a time T1 passing through the sensor 33a and a predetermined design value T (ΔTn = T−Tn: n =
1, 2, 3, 4) and the moving speed V of the intermediate transfer belt 7
From the displacement ΔYn of each color (ΔYn = ΔTn × V: n
= 1, 2, 3, 4).

With respect to the main scanning position shift shown in FIG. 2B, for example, by setting the registration pattern as an oblique line, the registration pattern can be detected by the sensor 3 in the color shift detecting means 13a in the same manner as described above.
The position shift of each color is calculated from the time of passing through 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, as shown in FIG. 5B, the registration pattern of the same color on the intermediate transfer belt 7 is detected by the color shift detecting means 13a.
And a time difference ΔTTn (n = 1, 2, 2) passing through the sensor 33a and the sensor 33b in the color shift detecting unit 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.

The magnification error shown in FIG. 2D is obtained by calculating the main scanning position shift in the color shift detecting means 13a and 13b as described above, and comparing the calculated value with a predetermined design value. The magnification error is calculated from the difference between.

The curvature error shown in FIG. 2E cannot be accurately measured by the conventional color misregistration detection operation using two sensors. Therefore, the error is reduced by increasing the assembling accuracy of the lens and the like in the exposure means 3.

Based on the four types of color misregistration amounts detected as described above, a color misregistration correction operation is performed in advance.

FIG. 6 is a configuration diagram of a conventional color misregistration correction mechanism of a scanning optical system in an exposure unit. In FIG. 6, the scanning optical system of the exposure unit 3 provided on the photosensitive drum 1 includes a polygon motor 61, a polygon mirror 62 mounted on the shaft of the polygon motor 61, an adjustment actuator 66, an adjustment actuator 67, , Mirror-shaped mirrors 63 and 64, which are movable up and down and up and down so that the mirror surfaces are held at right angles, and finally the scanning light beam is applied to the photosensitive drum 1.
And a return mirror 65 for irradiating the light. The adjusting actuator 66 includes the folding mirror 63,
64 is moved horizontally in the front-rear direction (the direction of arrow C in FIG. 6), and the adjustment actuator 67 is turned back.
64 is moved in the vertical direction (the direction of arrow D in FIG. 6).
As an actuator for performing these adjustments, a linear step actuator having a stepping motor, which is a drive source that moves linearly in steps, is used. The image data is optically modulated by a semiconductor laser (not shown),
The light enters the polygon mirror 62. Polygon mirror 62
The scanning light beam reflected by the mirrors 63, 64, and 6
5, the light is sequentially reflected and irradiated on the surface of the photosensitive drum 1. The irradiation position of the scanning light beam is controlled by a polygon motor 61, an adjustment actuator 66, and an adjustment actuator 67 which are driven independently.

With the scanning optical system configured as described above, the correction of the sub-scanning position shift shown in FIG. 2A and the main scanning position shift shown in FIG. Timing correction, phase control of the scanning start timing signal, or the phase control of the polygon motor, etc.
The correction of the skew error shown in FIG. 2C and the correction of the magnification error shown in FIG. 2D are performed by adjusting the irradiation position and adjusting the optical path length by the adjustment actuator 66 and the adjustment actuator 67.

[0027]

However, in the above-mentioned conventional configuration, when a registration pattern for examining the amount of color misregistration is transferred as a toner image onto the intermediate transfer belt, the eccentricity of the drive unit of the intermediate transfer belt or the like is reduced. Because the portion of the intermediate transfer belt where the toner image is transferred does not move at a constant speed (zero acceleration) due to shaft deviation of the driving unit or waving of the intermediate transfer belt, the toner image is transferred onto the intermediate transfer belt. The transfer position is not fixed but shifted, resulting in the registration pattern oscillating. Further, the toner image itself may not be accurately formed on the image forming unit due to the eccentricity of the driving unit of the image forming unit or the axial deviation of the driving unit. As a result, if the registration pattern is used to detect the amount of color misregistration, a different amount of color misregistration from the actual one will be detected. As a result, there is a problem that the print quality is deteriorated.

The present invention has been made in order to solve this problem, and more precisely corrects color misregistration by drawing a registration pattern with high accuracy, thereby obtaining an image with high print quality. It is an object of the present invention to provide a color image forming apparatus capable of performing the above.

[0029]

In order to solve the above-mentioned problems, the present color image forming apparatus comprises: an image conveying means for carrying and conveying an image on the surface; and an image conveying means for transmitting an image corresponding to image information of each color. A plurality of image forming means provided for each color to be formed thereon; and a registration pattern generating means for controlling the image forming means to form a registration pattern for each color on the image carrying means during a color misregistration detecting operation. And 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 provided for each color. .

According to this configuration, when the registration pattern is formed, the registration pattern is formed at the time when the combined image forming unevenness of the image forming means is minimized, so that the resist representing the more accurate color shift amount can be obtained. This makes it possible to provide a color image forming apparatus capable of forming an image with high print quality by improving the accuracy of color misregistration correction.

According to another aspect of the present invention, there is provided a color image forming apparatus which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means provided 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 detecting operation, and The image forming apparatus includes a color shift detecting means for detecting a color shift of an image from a translation pattern, and an image forming unevenness detecting means for detecting uneven image formation in a plurality of image forming means provided for each color.

According to this configuration, when forming the registration pattern, it is possible to form the registration pattern of each color at the time when the image forming unevenness of each of the image forming means is the least, thereby more accurate for each color. A registration pattern representing the amount of color misregistration can be formed, and the accuracy of color misregistration correction is improved, thereby providing a color image forming apparatus capable of obtaining an image with high print quality.

According to another aspect of the present invention, there is provided a color image forming apparatus which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means provided 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 detecting operation, and Color misregistration detecting means for detecting a color misregistration of an image from the translation pattern, image forming unevenness cycle detecting means for measuring a cycle of each of a plurality of image forming means provided for each color, and a plurality of measured image forming means And a phase adjusting means for adjusting the phase of each cycle.

According to this configuration, when forming the registration pattern, it is possible to form the registration pattern at the time when image forming unevenness is minimized in a state where the phases of the respective cycles of the plurality of image forming means are matched. Accordingly, it is possible to form a registration pattern representing a more accurate amount of color misregistration, and to provide a color image forming apparatus capable of obtaining an image with high print quality by improving the accuracy of color misregistration correction. can do.

According to another aspect of the present invention, there is provided a color image forming apparatus which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means provided 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 detecting operation, and Color misregistration detecting means for detecting a color misregistration of an image from a translation pattern, image forming unevenness detecting means for detecting image forming unevenness in a plurality of image forming means provided for each color, and detecting conveyance unevenness of the image conveying means. And a transport unevenness detecting means.

According to this configuration, when forming the registration pattern, it is possible to form the registration pattern at the time when the unevenness of conveyance of the image conveying means and the unevenness of image formation combined by the image forming means are minimized. Accordingly, it is possible to form a registration pattern representing a more accurate color shift amount, and to provide a color image forming apparatus capable of obtaining an image with high print quality by improving the accuracy of color shift correction. be able to.

According to another aspect of the present invention, there is provided a color image forming apparatus which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means provided 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 detecting operation, and A color misregistration detecting unit for detecting a color misregistration of an image from the translation pattern, an image forming nonuniformity detecting unit for detecting image forming nonuniformity in the plurality of image forming units installed for each of the colors, and a conveyance nonuniformity of the image conveying unit. It has a configuration provided with uneven conveyance detecting means.

According to this configuration, when forming the registration pattern, the registration of each color is performed at a point in time when the unevenness in conveyance is small, and at a point in time when the image formation unevenness of each of the plurality of image forming means installed for each color is minimal. It is possible to form a registration pattern, thereby enabling a registration pattern representing a more accurate amount of color misregistration to be obtained, and by improving the accuracy of color misregistration correction, obtaining an image with high print quality. And a color image forming apparatus capable of performing the above-described operations.

According to another aspect of the present invention, there is provided a color image forming apparatus which forms an image corresponding to image information of each color on the image conveying means. A plurality of image forming means provided 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 detecting operation, and Color misregistration detecting means for detecting a color misregistration of an image from the translation pattern, image forming unevenness cycle detecting means for measuring a cycle of each of a plurality of image forming means provided for each color, and a plurality of measured image forming means And a non-uniform transport detecting means for detecting the non-uniform transport of the image transport means.

According to this configuration, when forming a registration pattern, when the phases of the respective cycles of the plurality of image forming means are matched, the registration unevenness is minimized at the time when the conveyance unevenness is small and the image formation unevenness is minimized. This makes it possible to form a pattern, thereby making it possible to form a registration pattern representing a more accurate amount of color misregistration, and by improving the accuracy of color misregistration correction, it is possible to obtain an image with high print quality. A color image forming apparatus that can be provided.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color image forming apparatus according to a first aspect of the present invention comprises an image conveying means for carrying and conveying an image on the surface, and an image corresponding to image information of each color on the image conveying means. A plurality of image forming means installed for each color to be formed, and a 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 at the time of color misregistration detection operation A color misregistration detecting means for detecting a color misregistration 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 provided for each color. With this configuration, it is possible to form the registration pattern at the time when the combined image forming unevenness of the image forming unit is minimal. 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.

According to a second aspect of the present invention, there is provided a color image forming apparatus, comprising: an image carrying means for carrying and carrying an image on the surface; and each color forming an image corresponding 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 controlling the formation of a registration pattern for each color on the image carrying means by the image forming means at the time of color misregistration detection operation, and color misregistration detection for detecting color misregistration 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 provided for each color. With this configuration, a plurality of image forming means provided for each color are provided. By forming a registration pattern for each color at the time point when the image forming unevenness of each of the means is the least, the influence of drawing blur of the registration pattern is reduced, the registration pattern is drawn more accurately, and the amount of color shift This has the effect that the measurement of becomes highly accurate.

According to a third aspect of the present invention, there is provided a color image forming apparatus, comprising: an image carrying means for carrying and carrying an image on the surface; and each color forming an image corresponding 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 controlling the formation of a registration pattern for each color on the image carrying means by the image forming means at the time of color misregistration detection operation, and color misregistration detection for detecting color misregistration of an image from the registration pattern Means, an image forming unevenness cycle detecting means for measuring each cycle of the plurality of image forming means provided for each color, and a phase matching means for adjusting the phase of each cycle of the measured plurality of image forming means. According to this configuration, in a state where the phases of the respective cycles of the plurality of image forming units are matched with each other, the registration pattern is formed at the time point where the image forming unevenness is least, so that the registration pattern is formed. The effect of drawing blur is reduced, and the registration pattern is more correct. It is drawn in, with the effect that measurement of the color shift amount becomes high accuracy.

According to a fourth aspect of the present invention, there is provided a color image forming apparatus, comprising: an image carrying means for carrying and carrying an image on the surface; and each color forming an image corresponding 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 controlling the formation of a registration pattern for each color on the image carrying means by the image forming means at the time of color misregistration detection operation, and color misregistration detection for detecting color misregistration of an image from the registration pattern Means, unevenness in image formation in a plurality of image forming means provided for each color, and unevenness in image formation detecting means for detecting unevenness in image formation, and unevenness detecting means for detecting unevenness in transfer of the image conveying means, With this configuration, the registration pattern is formed at the time point where the unevenness of image transporting by the image transporting unit and the combined image forming unevenness of the image forming unit are minimized. The pattern is drawn more accurately and the amount of color misregistration is measured. It has the effect that it becomes highly accurate.

According to a fifth aspect of the present invention, there is provided a color image forming apparatus, comprising: an image carrying means for carrying and carrying an image on the surface; and a color image forming apparatus for forming an image corresponding 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 controlling the formation of a registration pattern for each color on the image carrying means by the image forming means at the time of color misregistration detection operation, and color misregistration detection for detecting color misregistration of an image from the registration pattern Means, unevenness in image formation in a plurality of image forming means provided for each color, and unevenness in image formation detecting means for detecting unevenness in image formation, and unevenness detecting means for detecting unevenness in transfer of the image conveying means, With this configuration, the registration pattern for each color is formed at a point in time when the transport unevenness is small, and at a point in time when the image forming unevenness of each of the plurality of image forming units provided for each color is the least. The effect of drawing blur is reduced, and the registration pattern 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, comprising: an image carrying means for carrying and carrying an image on the surface; and each color forming an image corresponding to the image information of each color on the image carrying means. A plurality of image forming means installed for each,
Registration pattern generating means for controlling the formation of a registration pattern for each color on the image carrying means by the image forming means at the time of color misregistration detection operation, and color misregistration detection for detecting color misregistration of an image from the registration pattern Means, an image forming unevenness cycle detecting means for measuring each cycle of the plurality of image forming means provided for each color, a phase matching means for adjusting the phase of each cycle of the measured plurality of image forming means, and an image The image forming apparatus further includes transport unevenness detecting means for detecting transport unevenness of the transport means. With this configuration, in a state where the phases of the respective cycles of the plurality of image forming units are matched, the transport unevenness is small, and By forming a registration pattern at the time of the least formation unevenness,
The effect of blurring of the registration pattern is reduced, the registration pattern is drawn more accurately, and the measurement of the amount of color misregistration becomes more accurate.

(Embodiment 1) FIG. 7 is a functional block diagram of a color image forming apparatus according to Embodiments 1 and 2 of the present invention, and FIG. 11 is a diagram showing images in a plurality of image forming units according to Embodiment 1 of the present invention. 6 is a graph showing a time series of the formation unevenness and the cycle of the combined image formation unevenness.

The structure of the image forming section of the color image forming apparatus according to the present embodiment is the same as the conventional structure as shown in FIG.

In FIG. 7, 71a, 71b, 71c,
Reference numeral 71d denotes a pattern for measuring transport unevenness at regular 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 that for forming a registration pattern. The image forming unevenness detecting means 72 is formed on the intermediate transfer belt 7 and measures the image forming unevenness of the image forming means by means such as detecting by the same procedure as the color misregistration detecting means 13. 71a, 71b, 7
1c and 71d, a registration pattern generating means for generating a registration pattern using the period of the image forming unevenness detected,
a, Pb, Pc, Pd are the image stations, 7 is
The intermediate transfer belt 13 serving as an image conveying means corresponds to the color misregistration detecting means 73, and the color misregistration detecting means 73 corresponds to the color misregistration detected by the color misregistration detecting means 13 as shown in FIGS. Color shift correction means for performing color shift correction.

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

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

In FIGS. 11A to 11D, the vertical axis represents the amount of uneven image formation in the image forming means for each color, and the horizontal axis represents time. Ta, Tb, Tc, and Td represent periods of each image forming unevenness. Each image forming unevenness has a cycle that depends on the cycle of each component (gear, pulley, etc.) in the image forming unit. This cycle may be obtained by using a design value that is known in advance, or, if there is no design value, by obtaining a frequency analysis of the output of an encoder (not shown) attached to the drive unit of each image forming unit. Can be. These image forming unevennesses are mainly a vibration system, and have periodicity, and the amount of the image forming unevenness does not diverge. Therefore, when viewed in chronological order, there always exist time points Xa, Xb, Xc, and Xd where the amount of image formation unevenness is small. The point in time when the amount of unevenness in image formation is small can be obtained in the same manner as the method for obtaining the above-mentioned period. In FIG. 11E, the vertical axis represents the difference between FIGS. 11A to 11D, and the horizontal axis represents time. As shown in FIG. 11E, when the image forming unevenness in the image forming unit of each color has a cycle, the image forming unevenness of the combined four colors of the image forming unevenness also has a cycle. It can be obtained from the image forming unevenness in the forming means. The combined image forming unevennesses of the respective image forming unevennesses also have periodicity and do not diverge, so that the portions Y1, Y2, and Y where the amount of the image forming unevenness is small are small.
3, Y4 exists. Therefore, Y1, Y2, Y3,
By forming a registration pattern at the position of Y4, it is possible to form a more accurate registration pattern with less influence of each image forming unevenness, and as a result, it is possible to detect a color shift amount and correct a color shift with high accuracy. Becomes

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

In the first embodiment, the registration pattern is formed at a time when the amount of the combined image forming unevenness is small. Is required. Therefore, instead of forming a registration pattern at a time when the amount of combined image forming unevenness is small, a registration for each color is performed at each of the image forming means at times Xa, Xb, Xc, and Xd where image forming unevenness is small. Forming a translation pattern. This eliminates the need for processing for obtaining combined image forming unevenness, and allows a more accurate registration pattern to be formed with less influence of each image forming unevenness. As a result, highly accurate color shift amount detection and color shift Correction becomes possible.

(Embodiment 3) FIG. 8 is a functional block diagram of a color image forming apparatus according to Embodiment 3 of the present invention.
FIG. 12 is a graph showing, in chronological order, image forming unevenness in a plurality of image forming units and a cycle of the combined image forming unevenness in a plurality of image forming units according to the third embodiment of the present invention.

In FIG. 8, reference numeral 81 denotes an image forming unevenness phase adjusting means for adjusting the phase of the image forming unevenness cycle in each image forming means. Other configurations are the same as those in the first embodiment, and a description of the configuration and operation will be omitted.

12A to 12F, the vertical axis represents the amount of uneven image formation in the image forming means of each color, and the horizontal axis represents time. Here, the case where the image forming unevenness cycle of each image forming unit is the same will be described for the case of two colors for simplicity. FIGS. 12A and 12B show image forming unevenness in image forming units of different colors. These 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. FIGS. 12D and 12E show image forming unevenness in image forming units of different colors. These 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 shift between two colors is
It becomes small as shown in FIG. in this way,
If the periods are the same, the difference is only the difference in amplitude if the phase is the same, and becomes larger if the phase is shifted. Therefore, first, the phase of each image forming unit is obtained by frequency analysis or the like, and the phases are matched. Thereafter, as shown in the first embodiment, by forming the registration pattern at a time point when the drawing unevenness is small, a more accurate registration pattern having less influence of the image forming unevenness than the method of the first embodiment is formed. As a result, high-accuracy color misregistration detection and color misregistration correction become possible.

(Embodiment 4) FIG. 9 is a functional block diagram of a color image forming apparatus according to Embodiments 4 and 5 of the present invention. FIG. 11 is a graph showing, in chronological order, periods of image forming unevenness in a plurality of image forming units according to Embodiment 1 of the present invention. These are the first embodiment
Therefore, the description of the configuration and operation is omitted.

In FIG. 9, reference numeral 91 denotes an uneven transfer belt detecting means for detecting uneven transfer in the intermediate transfer belt as the transfer means. Reference numeral 72 denotes registration using the period of the image forming unevenness detected by the image forming unevenness detecting means 71a, 71b, 71c, 71d and the period of the uneven transfer detected by the intermediate transfer belt unevenness detecting means 91. It is a registration pattern generating means for generating a pattern. Other configurations are the same as those in the first embodiment, and a description of the configuration and operation will be omitted.

As in the case of the image forming unevenness described in the first embodiment, the uneven transfer occurs at a cycle that depends on the cycle of each component (gear, pulley, etc.) of the intermediate transfer belt. This cycle may use a design value known in advance,
If there is no design value, the output can be obtained by a method such as frequency analysis of the output of an encoder (not shown) attached to the drive unit of the intermediate transfer belt. These transport irregularities
It is mainly a vibration system and has periodicity and the amount of uneven transport does not diverge. Therefore, when viewed in chronological order, there is always a time point (not shown) where the amount of transport unevenness is small, similarly to the image forming unevenness described in the first embodiment. The point at which the amount of uneven transport is small can also be determined in the same manner as the method of determining the period. The transport unevenness can be considered in the same manner as the image forming unevenness described in the first embodiment. Therefore, by forming a registration pattern at a time when the combined image forming unevenness of each image forming unevenness shown in the first embodiment is small and at a time when the uneven transfer is small, the influence of the uneven unevenness in the first embodiment is reduced. It is possible to form a small number of registration patterns, that is, more accurate than in the first embodiment. As a result, it is possible to detect a color misregistration amount and correct color misregistration with higher accuracy.

(Embodiment 5) FIG. 9 is a functional block diagram of a color image forming apparatus according to Embodiments 4 and 5 of the present invention. FIG. 11 is a graph showing, in chronological order, periods of image forming unevenness in a plurality of image forming units according to Embodiment 1 of the present invention. These are the first embodiment
2 and 2, the description of the configuration and operation is omitted.

As described in the fourth embodiment, the transport unevenness can be considered in the same manner as the image forming unevenness.
Therefore, for each image forming unit described in the second embodiment,
At time points Xa, Xb, Xc, and Xd at which image forming unevenness is small, and at a time point at which transport unevenness is small, a registration pattern for each color is formed. This eliminates the need for a process for obtaining combined image forming unevenness, and can form a registration pattern that is less affected by transport unevenness than in the second embodiment, that is, can form a more accurate registration pattern than in the second embodiment. Thus, it is possible to detect the color shift amount and correct the color shift more accurately.

(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 a diagram showing image forming unevenness in a plurality of image forming means according to Embodiment 3 of the present invention. 6 is a graph showing the cycle of image formation unevenness combined with the time series. Since these are the same as the third and fourth embodiments, the description of the configuration and operation is omitted.

The transport unevenness can be considered in the same manner as each image forming unevenness as described in the fourth embodiment.
Therefore, the phase of each image forming unit described in the third embodiment is obtained by frequency analysis or the like, and the phases are adjusted to form a registration pattern at a time when there is little drawing unevenness and at a time when there is little conveyance unevenness. In addition, it is possible to form a more accurate registration pattern than in the third embodiment, that is, it is possible to form a more accurate registration pattern than in the third embodiment. 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 provided for each color to be formed on the image carrying means, and a 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 misregistration detecting operation A pattern generation unit, a color shift detection unit that detects a color shift of an image from the registration pattern, and a transfer unevenness detection unit that detects uneven transfer in the image transfer unit, so that the registration can be performed at a time when the transfer unevenness is small. Registration pattern can be transferred, and the effect of registration pattern drawing blurring is reduced. An advantage of the present invention is that it is possible to provide a color image forming apparatus capable of obtaining an image with high printing quality by drawing a color pattern more accurately and measuring the amount of color misregistration with higher accuracy. can get.

According to the color image forming apparatus of the present invention, an image carrying means for carrying and carrying an image on the surface, and forming an image corresponding to the image information of each color on the image carrying means. A plurality of image forming units installed for each color, and a registration pattern generating unit for performing control to form a registration pattern for each color on the image conveying unit by the image forming unit during a color misregistration detecting operation; By providing a color misregistration detecting means for detecting a color misregistration of an image from a registration pattern and an image forming unevenness cycle detecting means of each of a plurality of image forming means provided for each color, a plurality of image forming irregularities are provided for each color. At the time when the image forming unevenness of each of the image forming means is the least,
The registration pattern can be transferred, the influence of blurring of the registration pattern is reduced, the registration pattern is drawn more accurately, and the measurement of the amount of color misregistration becomes more accurate, so that an image with high printing quality can be obtained. Has an advantageous effect of being able to provide a color image forming apparatus capable of obtaining the following.

According to a third aspect of the present invention, there is provided the color image forming apparatus according to the second aspect, wherein the measured phases of the respective cycles of the plurality of image forming units are matched. With the provision of the means, the registration pattern can be transferred in a state where the phases of the respective cycles of the plurality of image forming means are matched, and the influence of the drawing blur of the registration pattern of each color becomes the same, The high accuracy of the measurement of the shift amount has an advantageous effect that a color image forming apparatus capable of obtaining an image with high print quality can be provided.

According to the color image forming apparatus of the present invention, an image carrying means for carrying and carrying an image on the surface, and forming an image corresponding to image information of each color on the image carrying means. A plurality of image forming units installed for each color, and a registration pattern generating unit for performing control to form a registration pattern for each color on the image conveying unit by the image forming unit during a color misregistration detecting operation; A color misregistration detecting means for detecting a color misregistration of an image from a registration pattern, a transport unevenness detecting means for detecting transport unevenness in the image transport means, and an image forming unevenness cycle of each of a plurality of image forming means provided for each color By providing the detecting means, the level can be reduced at the time when the unevenness of the image forming means combined with the unevenness of the image forming means is minimized. The registration pattern can be transferred, the effect of the registration pattern drawing blur is reduced, the registration pattern is drawn more accurately, and the color misregistration amount is measured with high accuracy. Has an advantageous effect of being able to provide a color image forming apparatus capable of obtaining the following.

According to a fifth aspect of the present invention, there is provided the color image forming apparatus according to the fourth aspect, wherein a plurality of the color image forming apparatuses are provided at a time when the transport unevenness is small and for each color. The registration pattern can be transferred at the time when the image forming unevenness of each of the image forming means is the least, the influence of drawing blur of the registration pattern is reduced, the registration pattern is drawn more accurately, and the amount of color misregistration is reduced. The measurement has high accuracy, which has 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 present invention, an image carrying means for carrying and carrying an image on the surface, and forming an image corresponding to image information of each color on the image carrying means. A plurality of image forming units installed for each color, and a registration pattern generating unit for performing control to form a registration pattern for each color on the image conveying unit by the image forming unit during a color misregistration detecting operation; A color misregistration detecting means for detecting a color misregistration of an image from a registration pattern, a conveyance unevenness detecting means for detecting uneven conveyance in the image conveying means, and an image forming unevenness cycle of each of a plurality of image forming means provided for each color With the provision of the detecting means, in a state where the phases of the respective cycles of the plurality of image forming means are matched, the transport unevenness is small, and In the most less the time of forming the village,
The registration pattern can be transferred, the influence of blurring of the registration pattern is reduced, the registration pattern is drawn more accurately, and the measurement of the amount of color misregistration becomes more accurate, so that an image with high printing quality can be obtained. Has an advantageous effect of being able to provide a color image forming apparatus capable of obtaining the following.

[Brief description of the 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 conventional registration pattern and a displacement detection unit on an intermediate transfer belt.

FIG. 5 is a diagram showing a conventional arrangement pattern of a registration pattern on an intermediate transfer belt, a misregistration detection unit, and an output signal of a misregistration detection unit.

FIG. 6 is a configuration diagram of a color shift 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 Embodiment 3 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 chronological order, a cycle of image forming unevenness in a plurality of image forming units and a combined image forming unevenness in the plurality of image forming units according to the first embodiment of the present invention;

FIG. 12 is a graph showing, in a time series, image forming unevenness in a plurality of image forming units and a cycle of the combined image forming unevenness in a plurality of image forming units according to the third embodiment of the present invention;

[Explanation of symbols]

1, 1a, 1b, 1c, 1d Photoreceptor drum 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 feed roller 9 Sheet material 10 Paper feed cassette 11 Transfer roller 12 Fixing means 13 Color shift detecting means 14a, 14b Driving roller 31 Light source 32 Lens 33 Sensor 34-37 Resist Registration pattern 61 Polygon motor 62 Polygon mirror 63, 64, 65 Folding mirror 66, 67 Adjustment actuator 71a, 71b, 71c, 71d Image forming unevenness detecting means 72 Registration generating means 73 Color shift correcting means 81 Image forming unevenness phase matching means 91 Intermediate transfer belt Sending unevenness detecting means Pa, Pb, Pc, Pd Image forming station Ta, Tb, Tc, Td, Te, Tf Image forming unevenness cycle Xa, Xb, Xc, Xd Time point when image forming unevenness is small Y1, Y2, Y3, Y4 Composite Time point at which image formation unevenness is small Z Phase difference of image formation unevenness

Claims (6)

[Claims] 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 corresponding to the image information of each color on the image carrying means; 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 at the time of a displacement detecting operation, and color misregistration detecting means for detecting a color misregistration of an image from the registration pattern A color image forming apparatus comprising: an image forming unevenness detecting unit configured to detect image forming unevenness in a plurality of image forming units provided for each of the colors; and a combined image forming unit of the image forming unit. At the point of least unevenness, it is provided with a registration pattern generating means for forming the registration pattern. Color image forming apparatus according to symptoms. 2. The image forming apparatus according to claim 1, wherein said registration pattern generating means includes an image forming unevenness cycle detecting means of each of a plurality of image forming means provided for each color, and each of the plurality of image forming means provided for each color. 2. The color image forming apparatus according to claim 1, wherein a registration pattern for each color is formed at a point in time when formation unevenness is minimized. 3. An image forming unevenness cycle detecting means for measuring a cycle of each of a plurality of image forming means provided for each color, and a phase matching means for adjusting a phase of each of the measured plurality of image forming means. Wherein the registration pattern generating means forms the registration pattern at a time point when image forming unevenness is minimized in a state where phases of respective periods of a plurality of image forming means are matched. 2. The color image forming apparatus according to 1. 4. An image forming apparatus according to claim 1, further comprising a transport unevenness detecting means for detecting transport unevenness of said image transport means, wherein said registration is performed at a time point when the transport unevenness of said image transport means and the image forming unevenness of said image forming means are minimized. The color image forming apparatus according to claim 1, wherein the pattern is formed. 5. An image forming apparatus according to claim 1, further comprising a transport unevenness detecting means for detecting transport unevenness of said image transport means, wherein said registration pattern generating means detects a plurality of image forming means provided for each color at a time when the transport unevenness is small. 3. The color image forming apparatus according to claim 2, wherein a registration pattern for each color is formed at a time point when each image forming unevenness is minimized. 6. An image forming apparatus according to claim 1, further comprising transport unevenness detecting means for detecting transport unevenness of said image transport means, wherein said registration pattern generating means reduces transport unevenness when a plurality of image forming means are in phase with each other. 4. The method according to claim 3, wherein the registration pattern is formed at a time when image formation unevenness is minimized.
The color image forming apparatus as described in the above.