JP2002357942A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus where compensation of color slippage can be carried out speedily at a high precision. SOLUTION: In the apparatus, toner images for detection of deviation in position 200 are formed in each position where the phases are different by 180 deg. on a secondary intermediate transfer drum 7 so that any deviation in array of spacing of periodical toner patterns due to unevenness in rotation of the secondary intermediate transfer drum 7 is dispelled. In this case, the positions of 4 single color toner images in relationship to each another are adjusted by deriving the relationship in positions of each toner pattern forming these toner images for detection of deviation in position 200 through a transfer roll 8 and an optical sensor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used for an electrophotographic copying machine, a printer, and the like.

[0002]

2. Description of the Related Art In recent years, with the spread of colorization of commercial documents and the like, tandem type image forming apparatuses have been widely used.
In order to form a color image on paper, this tandem-type image forming apparatus first forms a toner image of each color toner on a plurality of rotating image carriers, and forms the toner images on the plurality of image carriers. The toner images of the respective colors are transferred onto one rotating intermediate transfer member via another intermediate transfer member except for the one intermediate transfer member, or directly from each of the plurality of image carriers so as to overlap. I do. Next, the multicolor toner images transferred onto the one intermediate transfer member are
The toner image is transferred onto a sheet of recording medium conveyed via a predetermined conveyance path by the action of a rotating bias application roll that applies a predetermined transfer bias to the toner image. Further, the toner image transferred onto the paper is fixed using a fixing device. Thus, a color image composed of the fixed toner image is formed on the paper. In this image forming apparatus, a color image is obtained by simultaneously forming a toner image of each color toner on a plurality of image carriers, so that a color image can be formed at a high speed.

In such an image forming apparatus, color misregistration may occur in a color image formed on a sheet due to uneven rotation of an image carrier and an intermediate transfer member. Japanese Patent Application Laid-Open No. 2000-250280 discloses a method for detecting uneven transport of an image transport unit, and using a pattern for correcting color misregistration formed based on the uneven transport to detect toner images of each color constituting a color image. There has been proposed a technique for performing color misregistration correction so as to overlap with high accuracy. According to the technique proposed in this publication, even when rotational unevenness of the image carrier or the intermediate transfer member occurs, color misregistration correction can be performed with high accuracy.

[0004]

However, according to the technique proposed in the above-mentioned publication, it is necessary to detect uneven transport of the image transport means in advance in order to form a color shift correcting pattern. There is a problem that the time for performing the correction is long.

The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus capable of performing color shift correction quickly and with high accuracy.

[0006]

An image forming apparatus according to the present invention for achieving the above object forms a toner image of each color toner on a plurality of rotating image carriers, and forms the toner images on the plurality of image carriers. The toner images of the respective colors are superimposed on one rotating intermediate transfer member via another intermediate transfer member excluding the one intermediate transfer member, or directly from each of the plurality of image carriers. Transferring a plurality of color toner images transferred on the one intermediate transfer member onto a recording medium conveyed via a predetermined conveyance path, applying a predetermined transfer bias to the toner images, An image forming apparatus that forms a color image composed of a fixed toner image on a recording medium by transferring the image by the action of a rotating bias applying roll and fixing the toner image transferred on the recording medium using a fixing device. To And a misregistration detection toner image that forms a misregistration detection toner image in which toner patterns of single-color toners are arranged to detect misregistration in the rotation direction of the image carrier between toner images using a plurality of color toners. Forming means, and receiving light reflected from each toner pattern constituting the toner image for position shift detection formed by the toner image forming means for position shift detection, obtaining a light receiving signal, and forming each toner based on the light receiving signal. Pattern position measuring means for determining the positional relationship between the patterns, and position adjusting means for adjusting the position between the plurality of single-color toner images based on the positional relationship between the toner patterns determined by the pattern position measuring means, The position deviation detecting toner image forming unit is configured to control a cycle caused by uneven rotation of one of the image carrier and the intermediate transfer body. As arrangement interval deviation of the toner pattern is canceled, the misregistration detection toner image on its one rotational direction at different positions of the rotating body, and characterized in that a plurality of forming or transcription.

Here, the misregistration detecting toner image forming means sequentially converts the plurality of misregistration detecting toner images into approximately n / l (l ≠ n; l, n: It is preferable that each of them is formed once at a position where the phase is shifted by an integer number of turns.

Further, any one of the rotating members may be one of the intermediate transferring members or a plurality of intermediate transferring members having the same diameter.

Further, the toner image forming means for detecting the positional deviation is sequentially rotated by 1 / m (m is an integer of 2 or more) on the rotating member having the smallest diameter among the image bearing member and the intermediate transfer member. It is preferable to form a misregistration detection toner image in which the distance between the toner patterns is adjusted so that the same toner pattern appears repeatedly at a position where the phase is displaced m times.

The position deviation detecting toner image forming means finally forms the position deviation detecting toner image on the bias applying roll, and the pattern position measuring means comprises the bias applying roll. The light receiving signal may be obtained by receiving the reflected light from each of the toner patterns forming the misregistration detecting toner image formed above.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic configuration diagram of an embodiment of the image forming apparatus of the present invention.

The image forming apparatus 100 shown in FIG. 1 has yellow (Y), magenta (M), cyan (C), and black (K).
Drums 1Y, 1M, 1C, 1K corresponding to the colors of
(Examples of a plurality of image carriers according to the present invention, each having a diameter (φ) of 20 mm).
These photosensitive drums 1Y, 1M, 1C, 1K rotate clockwise in FIG.

The image forming apparatus 100 includes chargers 2Y, 2M, 2C, 2K for uniformly charging the photosensitive drums 1Y, 1M, 1C, 1K, and photosensitive drums 1Y, 1K.
A controller to be described later including a scanning optical system for irradiating spot light on the surfaces of M, 1C, and 1K according to image signals of each color to form electrostatic latent images of each color on each of the photosensitive drums 1Y, 1M, 1C, and 1K. 3, and the respective color developing units 4Y, 4Y, which develop the respective photosensitive drums 1Y, 1M, 1C, 1K on which the electrostatic latent images are formed using yellow, magenta, cyan, and black toners.
4M, 4C, 4K, and each of the photosensitive drums 1Y, 1M, 1
Cleaners 5Y and 5 for removing residual toner on C and 1K
M, 5C, and 5K.

Further, in the image forming apparatus 100, the primary intermediate transfer drum 6_1 (diameter (diameter) where the yellow and magenta toner images formed on the respective photosensitive drums 1Y and 1M are electrostatically transferred so as to overlap each other. (φ) is 40mm)
And the primary intermediate transfer drum 6_2 (diameter (φ) is 40 m) on which the cyan and black toner images formed on the photosensitive drums 1C and 1K are electrostatically transferred so as to overlap each other.
m). These primary intermediate transfer drums 6
_1 and 6_2 rotate counterclockwise.

In the image forming apparatus 100, the secondary intermediate transfer drum 7 (diameter (φ) is 40 mm) on which the toner images formed on the primary intermediate transfer drums 6_1 and 6_2 are electrostatically transferred so as to overlap each other. Is provided. The secondary intermediate transfer drum 7 rotates clockwise.

Further, the image forming apparatus 100 includes a paper feed cassette 11 for supplying the paper P as a recording medium, and a paper separating half-roll 12 for separating the paper P stored in the paper feed cassette 11 one by one. And a paper feed roll pair 13 for feeding the paper P from the paper separation half-moon roll 12 in advance.
And a paper transport roll pair 14_1 that transports the paper P
And a paper standby roll pair 15 for holding the paper P by forming a desired amount of paper curl.

The image forming apparatus 100 includes a transfer roller 8 (the present invention) which transfers a toner image from the secondary intermediate transfer drum 7 to a sheet P, and on which a toner image for detecting misregistration to be described later is formed. The diameter (φ) is 20 mm) and the amount of reflected light from each toner pattern constituting the toner image for detecting the displacement formed on the transfer roll 8 is measured. And a cleaner 10 for cleaning the surface of the transfer roll 8.

Further, the paper P
Roll 17 for heating and pressing the toner image transferred to
a, a fixing unit 17 comprising a pressure roll 17b;
Fuser exit roll pair 1 that transports paper P that has passed through 7
9, a fuser exit switch 20 for detecting the trailing end of the sheet P that has passed through the fixing device 17, and a sheet transport roll pair 14_2
And a pair of outlet rolls 18 for sending out the paper P.

The image forming apparatus 100 includes a fixing device 1
7, a paper transport roll pair 14_3 that transports the paper P on which an image has been fixed on one side again, with the front and back reversed.
A manual feed roll pair 16 for feeding desired paper P from outside the image forming apparatus 100;
And a paper transport roll pair 14_4 for transporting the paper.

The controller 3 uses four color toners of yellow, magenta, cyan, and black to detect a positional shift in which toner patterns of single-color toners are arranged for detecting a positional shift between toner images in the process direction. A misregistration detection toner image forming means 31 for forming a toner image is provided. Here, the misregistration detection toner image forming unit 3
1 for the misregistration detection toner image formed by
This will be described with reference to FIG.

FIG. 2 is a view showing an example of a misregistration detecting toner image formed by the misregistration detecting toner image forming means.

FIG. 2 shows a position shift detecting toner image 20 formed over one round of the transfer roll 8 shown in FIG.
0 is shown. This misregistration detection toner image 20
0 has, at the beginning, a black toner pattern KT for a trigger pulse having a larger line width than other toner patterns. By having such a toner pattern KT, measurement of the passage time (the width of the toner pattern and the interval between the toner patterns) of the toner patterns of each color, which will be described later, and the color of the next toner pattern from the toner pattern KT. Can be easily specified. In addition, the toner image 200 for detecting misregistration has six toner patterns K (black), C (cyan),
K (black), M (magenta), K (black), Y (yellow)
Has four blocks consisting of

The description will be continued with reference to FIG. The controller 3 receives the reflected light from each of the toner patterns constituting the misregistration detection toner image 200 formed by the misregistration detection toner image forming means 31 by the optical sensor 9 to obtain a light reception signal. A pattern position measuring means 32 for obtaining a positional relationship between the respective toner patterns shown in FIG. 2 based on the signal is provided. For example, as shown in FIG. 2, the positional relationship between the toner pattern K (black) and the toner pattern C (cyan) (registration deviation ΔT between K and C) is ΔT = (T1 + T2) − (T1 + T2 + T3 + T4) /
2 (where T1 and T3 indicate the pattern widths of the toner patterns K and C. Further, T2 and T4 indicate
The interval between the toner patterns K and C and the interval between the toner patterns C and K are shown.

FIG. 3 is a diagram showing the amount of misalignment between the toner patterns of each color.

In FIG. 3, when the toner pattern K (black) is used as a reference line, the photosensitive drum 1 with respect to the reference line is shown.
Secondary intermediate transfer drum 7 for one rotation of Y, 1M, 1C, 1K
, And the toner patterns Y, Y at the conveyance distance of the paper P corresponding to the pitch of 3/2 of the secondary intermediate transfer drum 7
The displacement amount (mm) of M and C is shown. Ideally, when the deviation amounts of the toner patterns Y, M, and C are averaged, they overlap the reference line. Here, even if the number of samplings is small, the average value can be made closer to the ideal value by canceling the peak value.

Further, the controller 3 adjusts the positions of the four single-color toner images constituting the toner images of a plurality of colors based on the positional relationship between the toner patterns obtained by the pattern position measuring means 32. Means 33
Is provided.

The toner image forming means 31 for detecting the positional deviation
Are photosensitive drums 1Y, 1M, 1C, 1K (φ: 20 m
m) and any of the primary intermediate transfer drums 6_1, 6_2, and the secondary intermediate transfer drum 7 (φ: 40 mm). Are formed at different positions in the rotation direction of the secondary intermediate transfer drum 7 so that the periodic deviation of the arrangement interval of the toner pattern due to the above is canceled.

In the image forming apparatus 100 according to the present embodiment, different positions of the secondary intermediate transfer drum 7 are changed so that the periodic toner pattern arrangement interval deviation caused by uneven rotation of the secondary intermediate transfer drum 7 is canceled. A toner image 200 for detecting misregistration is formed on each of the toner images. The positional relationship between the respective toner patterns constituting the toner image 200 for misregistration detection is obtained via the transfer roll 8 and the optical sensor 9 to obtain four positions. Adjust the positions of the single color toner images. Thus, at each of the different positions of the secondary intermediate transfer drum 7,
Since the positional deviation detecting toner image 200 is formed so as to cancel the periodic deviation of the arrangement interval of the toner pattern caused by the rotation unevenness of the secondary intermediate transfer drum 7, these positional deviation detecting toner images 200 are formed. The positional relationship between each of the constituent toner patterns is obtained and averaged, and based on the averaged positional relationship, the positional relationship between the four single-color toner images is adjusted, so that color misregistration correction can be performed with high accuracy. . Further, unlike the conventional technology of detecting the uneven transfer of the image transfer unit and forming a pattern for correcting the color shift, there is no need to detect the uneven transfer in advance, and the time for performing the color shift correction is short. I'm done.

More specifically, the misregistration detection toner image forming means 31 transfers the misregistration detection toner image 200 to each of the positions on the secondary intermediate transfer drum 7 which are sequentially shifted in phase by 3/2 revolutions. Form. For this reason, the toner image for detecting the positional deviation is located between a predetermined position (for example, the maximum eccentric direction position) of the secondary intermediate transfer drum 7 and a position (for example, the minimum eccentric direction position) 180 ° shifted from the predetermined position. 200 are respectively formed. Thus, the secondary intermediate transfer drum 7
However, since the toner image 200 for detecting misregistration is formed at a position 180 degrees out of phase with each other, it is necessary to obtain the positional relationship between the toner patterns constituting the misregistration detecting toner image 200 with high accuracy. Can be.

Further, a toner image forming means 3 for detecting a displacement is provided.
Reference numeral 1 denotes a toner such that the same toner pattern repeatedly appears on the photosensitive drums 1Y, 1M, 1C, and 1K, which are rotating bodies having the minimum diameter (φ: 20 mm), at positions sequentially shifted by 1/4 turn. A toner image 200 for detecting misregistration in which the distance between the patterns is adjusted is formed. Since the misregistration detection toner image 200 formed in this way has four blocks composed of a combination of four colors, each toner pattern is averaged by averaging the positional relationship between the color toner patterns in these four blocks. The mutual positional relationship can be obtained with high accuracy.

Further, a toner image forming means 3 for detecting a displacement is provided.
Numeral 1 is a device for finally forming a position shift detecting toner image 200 on the transfer roll 8, and the pattern position measuring means 32 constitutes the position shift detecting toner image 200 formed on the transfer roll 8. Light reflected from each toner pattern is received by the optical sensor 9 to obtain a light receiving signal.

FIG. 4 is a diagram showing each interval in a plurality of misregistration detecting toner images.

The interval t1 shown in FIG. 4 indicates an interval corresponding to a 3/2 circumferential pitch of the secondary intermediate transfer drum 7 (a position where the phase is shifted by n / 1 rounds in the present invention). The interval t2 is the interval between the lines forming the toner pattern, that is, the quarter pitch of the photosensitive drums 1Y, 1M, 1C, and 1K (the position where the phase is shifted by 1 / m round in the present invention). Indicates the interval. Further, the interval t3 indicates an interval for one round of the transfer roll 8 shown in FIG.

To form a color image with the image forming apparatus 100, first, each of the photosensitive drums 1Y, 1M, 1C,
A toner image is formed on each of 1K by yellow, magenta, cyan, and black toners. Next, the toner images of the respective colors formed on the photosensitive drums 1Y, 1M, 1C and 1K are transferred onto the secondary intermediate transfer drum 7 so as to overlap with each other via the primary intermediate transfer drums 6_1 and 6_2. Further, a predetermined transfer bias is applied to the toner image of a plurality of colors transferred on the secondary intermediate transfer drum 7 onto the sheet P conveyed through a predetermined conveyance path, and the toner image is rotated. Transfer by the action of the transfer roll 8
The toner image transferred above is fixed using the fixing device 17. Thus, a color image composed of the fixed toner image is formed on the paper P.

In the present embodiment, the example of the secondary intermediate transfer drum 7 has been described as one of the rotating bodies according to the present invention. However, the present invention is not limited to this, and the primary intermediate transfer drums 6_1, 6_2, Any one or more of the secondary intermediate transfer drums 7 may be used.

Further, in the present embodiment, an example has been described in which the two toner images 200 for detecting the positional deviation are formed on the secondary intermediate transfer drum 7 at positions sequentially shifted in phase by 3/2 rotation. According to the present invention, a plurality of misregistration detecting toner images are sequentially shifted by approximately n / l (l ≠ n; l and n are all integers) on any one of the rotating bodies. What is necessary is just to form once.

Further, in the present embodiment, the photosensitive drum 1
A position shift detection toner image 200 in which the intervals between the toner patterns are adjusted such that the same toner pattern repeatedly appears at positions shifted in phase by 1/4 turn on Y, 1M, 1C, and 1K. Although the present invention has been described with reference to an example, the present invention is not limited to this.
(M is an integer of 2 or more) It is only necessary to form a toner image for detecting misregistration in which the intervals between toner patterns are adjusted such that the same toner pattern appears repeatedly m times at positions shifted in phase by circumference. .

[0039]

As described above, according to the image forming apparatus of the present invention, the color misregistration can be corrected quickly and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of a misregistration detection toner image formed by a misregistration detection toner image forming unit;

FIG. 3 is a diagram illustrating a positional shift amount between toner patterns of each color.

FIG. 4 is a diagram showing each interval in a plurality of misregistration detection toner images.

[Explanation of symbols]

1Y, 1M, 1C, 1K Photoconductor drum 2Y, 2M, 2C, 2K Charger 3 Controller 4Y, 4M, 4C, 4K Developing unit 5Y, 5M, 5C, 5K, 10 Cleaner 6_1, 6_2 Primary intermediate transfer drum 7 Secondary Intermediate transfer drum 8 Transfer roll 9 Optical sensor 11 Paper feed cassette 12 Paper separation half moon roll 13 Paper feed roll pair 14_1, 14_2, 14_3, 14_4 Paper transport roll pair 15 Paper standby roll pair 16 Manual paper feed roll pair 17 Fixing device 17a Heating Roll 17b Pressure Roll 18 Outlet Roll Pair 19 Fuser Outlet Roll Pair 20 Fuser Exit Switch 31 Toner Image Forming Means for Detecting Misalignment 32 Pattern Position Measuring Means 33 Position Adjusting Means 100 Image Forming Apparatus 200 Toner Image for Detecting Misalignment

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA21 DE02 DE07 DE10 EB04 EC03 EC06 EC07 EC09 ED24 EE02 2H030 AA01 AB02 AD17 BB23 BB42 BB46 BB54 BB56 BB63 2H200 FA04 GA23 GA44 GA47 GB22 HA02 HB12 HB22 J10 JA20 JA28 JC02 NA01 PB13 PB16

Claims (5)

[Claims] 1. A toner image of each color is formed on a plurality of rotating image carriers, and the toner images of each color formed on the plurality of image carriers are formed on one rotating intermediate transfer member. The transfer is performed via another intermediate transfer member excluding the one intermediate transfer member, or directly from each of the plurality of image carriers, so as to overlap each other. The toner image is transferred onto a recording medium conveyed via a predetermined conveyance path by the action of a rotating bias applying roll that applies a predetermined transfer bias to the toner image and is transferred onto the recording medium. An image forming apparatus that forms a color image composed of a fixed toner image on the recording medium by fixing the formed toner image using a fixing device; Rotational position A misregistration detection toner image forming means for forming a misregistration detection toner image in which a toner pattern of each single color toner is arranged for misregistration detection; and a misregistration detection formed by the misregistration detection toner image forming means. A pattern position measuring means for receiving reflected light from each toner pattern constituting the toner image to obtain a light receiving signal, and calculating a positional relationship between the toner patterns based on the light receiving signal; Position adjusting means for adjusting the positions of the plurality of single-color toner images based on the relative positional relationship between the toner patterns. The position shift detection is performed so that the periodic gap shift of the toner pattern due to the uneven rotation of one of the rotating bodies is canceled. An image forming apparatus for forming or transferring a plurality of output toner images at different positions in the rotation direction of any of the rotating members. 2. The method according to claim 1, wherein the misregistration detection toner image forming unit sequentially converts the plurality of misregistration detection toner images into substantially n / l (l ≠ n; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed one time each at a position shifted in phase by each circumference. 3. The image forming apparatus according to claim 1, wherein the one of the rotating bodies is one of the intermediate transfer bodies or a plurality of intermediate transfer bodies having the same diameter. 4. The toner image forming means for detecting misregistration, wherein each of the image bearing members and the intermediate transfer member has a minimum rotation of 1 / m (m is an integer of 2 or more) on the rotating member. 3. A toner image according to claim 1, wherein a toner image for detecting a positional shift is formed in which the distance between the toner patterns is adjusted so that the same toner pattern appears repeatedly at a position shifted in phase. Image forming device. 5. The apparatus according to claim 5, wherein the toner image forming means for detecting misregistration forms the toner image for detecting misregistration on the bias applying roll finally. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to receive light reflected from each of the toner patterns constituting the toner image for detecting misregistration formed thereon to obtain a light receiving signal.