JP3186587B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex image forming apparatus having a plurality of image forming means, such as a tandem type color copying machine or a color printer, in which different colors formed by the respective image forming means are formed. The present invention relates to a registration control system for detecting and correcting a color shift component of an image, and more particularly to an image forming apparatus capable of accurately detecting a so-called AC vibration component, which is a periodic fluctuation component generated in each image forming means. is there.

[0002]

2. Description of the Related Art In recent years, documents processed in offices and the like have rapidly become colorized, and image forming apparatuses such as copiers, printers, and facsimile machines that handle these documents have also been rapidly colorized. At present, these color devices tend to have higher image quality and higher speed with higher quality and faster office processing in offices and the like. As a color device that can meet such a demand, for example, each image forming unit is provided for each color of black (K), yellow (Y), magenta (M), and cyan (C), and is formed by each image forming unit. Various so-called tandem-type color image forming apparatuses for forming a color image by multiply transferring images of different colors onto a conveyed transfer material or an intermediate transfer body have been proposed and commercialized.

A tandem type color image forming apparatus of this type is, for example, as follows. As shown in FIG. 46, this tandem type color image forming apparatus includes a black image forming unit 200K for forming a black (K) image and a yellow image forming unit 200Y for forming a yellow (Y) image. And a magenta image forming unit 200M for forming a magenta (M) color image
And four image forming units of a Sian color image forming unit 200C for forming an image of the Sian (C) color.
00Y, 200M, and 200C are horizontally arranged at a fixed interval from each other. Further, below the four image forming units 200K, 200Y, 200M, and 200C of the black, yellow, magenta, and cyan colors, the image forming units 200K, 200Y, and 200M are electrostatically attracted to the transfer paper 201. , A transfer belt 202 as an endless transfer material carrier that conveys the transfer sheet 201 over the transfer position of 200C.

The above four image forming units 200K, 200 of black, yellow, magenta and cyan colors.
Y, 200M, and 200C are all configured similarly, and these four image forming units 200K, 200C
As described above, Y, 200M, and 200C are configured to sequentially form black, yellow, magenta, and cyan toner images, respectively. The image forming units 200K, 200Y, 200M, and 20 for each of the above colors
0C is provided with a photosensitive drum 203, and the surface of the photosensitive drum 203 has a scorotron 20 for primary charging.
After being uniformly charged by 4, an image forming laser beam 205 is scanned and exposed according to image information to form an electrostatic latent image. The electrostatic latent image formed on the surface of the photosensitive drum 203 is stored in each of the image forming units 200K, 200Y,
The toners of black, yellow, magenta, and cyan are developed by the 200M and 200C developing units 206 to form visible toner images. These visible toner images are subjected to pre-transfer charging by the pre-transfer charger 207. After the transfer, the transfer belt 20 is charged by the transfer charger 208.
2 is sequentially transferred to the transfer paper 201 held on the sheet 2. The transfer paper 201 on which the toner images of the black, yellow, magenta, and cyan colors have been transferred is a transfer belt 2
After the separation from the sheet 02, a fixing process is performed by a fixing device (not shown), and a color image is formed.

In the drawing, reference numeral 209 denotes a photoreceptor cleaner,
Reference numeral 210 denotes a photosensitive member discharging lamp, 211 denotes a sheet peeling corotron, 212 denotes a transfer belt discharging corotron, 213 denotes a transfer belt cleaner, and 214 denotes a cleaning pretreatment corotron.

The tandem-type color image forming apparatus configured as described above is a system in which one image is formed using a plurality of image forming units, so that a color image can be formed at a considerably high speed. It is possible. However, if the speed of image formation is increased, the alignment of images formed by the image forming units of each color, that is, color registration (hereinafter referred to as “register”) frequently deteriorates, and high image quality is maintained. Therefore, it has been extremely difficult to achieve both high image quality and high speed.
This is because the position and size of each image forming unit itself and the position and size of each component in the image forming unit are delicate due to a change in the internal temperature of the color image forming device and an external force applied to the color image forming device. Due to the change. Of these, changes in the internal temperature and external forces are inevitable.For example, daily operations such as recovery of paper jams, replacement of parts due to maintenance, and movement of the color image forming apparatus require external forces to be applied to the color image forming apparatus. Will be added.

Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 1-281468, a plurality of image forming devices for forming a visible image corresponding to document image information and also forming a visible image of a position detection mark are disclosed. And a moving member that sequentially moves and passes through a transfer area that transfers a visible image corresponding to the document image information formed by each of the image forming units or the visible image of the position detection mark, and a moving member in the transfer area. A position detection mark detection unit provided on the downstream side in the movement direction and detecting a position detection mark transferred on the moving member, and transferring the mark based on a detection signal output from the position detection mark detection unit. An image forming apparatus configured to control each of the image forming units in order to correct an image shift has already been proposed.

When this transfer image shift correction technique is applied to a so-called tandem-type color image forming apparatus shown in FIG. 46, as shown in FIG. Each image forming unit 200
K, 200Y, 200M, and 200C, a plurality of color misregistration detection patterns 220K and 22 along the traveling direction of the transfer belt 202 and the direction orthogonal to the traveling direction.
0Y, 220M, 220C and 221K, 221Y, 2
21M, 221C are formed at predetermined intervals over the entire circumference of the transfer belt 102, and these color misregistration detection patterns 220K, 220Y, 220M, 220C, and 221 are formed.
K, 221Y, 221M, and 221C
A plurality of light-receiving pixels are sampled by a line-type light-receiving element 222 such as a CCD sensor in which a plurality of light-receiving pixels are linearly arranged using the transmitted light from
K, 220Y, 220M, 220C and 221K, 22
1Y, 221M and 221C are calculated, and each image forming unit 200 is set so that the interval becomes equal to a predetermined reference value.
By correcting the positions of K, 200Y, 200M, and 200C and the image forming timing, higher image quality is realized. The color shift detection patterns 220K, 220Y, 2
20M, 220C and 221K, 221Y, 221M,
221C is the transfer belt cleaner 2 after sampling.
13 to be removed.

In the case of the color image forming apparatus constructed as described above, as shown in FIG. 47, predetermined color misregistration detection patterns 220K, 220Y,
220M, 220C and 221K, 221Y, 221
M, 221C are formed over the entire circumference of the transfer belt 202, and these color misregistration detection patterns 220K, 220
Y, 220M, 220C and 221K, 221Y, 22
1M and 221C are detected by a line type light receiving element 222 composed of a CCD sensor or the like, and a color misregistration detection pattern 2
20K, 220Y, 220M, 220C and 221K,
221Y, 221M and 221C are calculated for each color interval,
By correcting the positions and the image forming timings of the image forming units 200K, 200Y, 200M, and 200C so that this becomes equal to a predetermined reference value, high image quality is realized.

However, the above-described color image forming apparatus has the following problems. That is,
The color misregistration detection patterns 220K, 220Y, 220
M, 220C and 221K, 221Y, 221M, 22
As shown in FIG. 47, 1C is formed over the entire circumference of the transfer belt 202 including the seam portion 202a, and the color shift detection patterns 220 and 221 are removed by the transfer belt cleaner 213 after sampling. At this time, the seam portion 202a of the transfer belt 202
Has small steps, it is difficult to completely remove the color shift detection patterns 220 and 221 formed on the seam portion 202a of the transfer belt 202 by the transfer belt cleaner 213.
The toner forming the color shift detection patterns 220 and 221 remains in the second seam portion 202a. As described above, when the toner forming the color misregistration detection patterns 220 and 221 remains on the seam portion 202a of the transfer belt 202, the remaining toner is held and conveyed on the transfer belt 202 when the next color image is formed. There is a problem in that it adheres to the back surface and causes back surface contamination.

The color shift detecting pattern 220
K, 220Y, 220M, 220C and 122K, 12
2Y, 122M, and 122C are formed over the entire circumference of the transfer belt 202 including the seam portion 202a. At this time, since the seam portion 202a of the transfer belt 202 has a minute step as described above, the color shift detection patterns 220 and 221 formed on the seam portion 202a of the transfer belt 202 have density Variations and chippings may occur. Thus, the transfer belt 20
If the color misregistration detection patterns 220 and 221 formed on the second seam portion 202a have unevenness or lack of density, the color misregistration detection patterns 220 and 221 are detected by the line-type light receiving element 222. There is a problem that a detection error occurs.

Therefore, the present applicant uses the control means to
In the case of controlling the image sampling correction, the sampling start point and the sample width of the sampling control means are set to repeatedly generate a registration deviation measurement pattern, and the sampling data or arithmetic processing data is integrated to obtain a pattern position, There has already been proposed a sampling correction method in which the sampling start point and the sample width of the sampling control means are set to improve the detection accuracy of the registration deviation measurement pattern (JP-A-6-253151).

[0013]

However, the prior art described above has the following problems. That is, in the case of the registration image sampling correction method of the multiple image forming apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-253151, each image forming operation is performed by changing the internal temperature of the color image forming apparatus or applying an external force to the apparatus. A color registration deviation (hereinafter, referred to as a “DC color registration deviation”) in which the position and size of the unit itself, and furthermore, the position and size of the components in the image forming unit slightly change in size and direction due to subtle changes. ) Is detected and corrected. However, in the color registration misregistration, in addition to the DC component, mainly a rotating body such as a photosensitive drum or a belt drive roll is a variable factor. (Hereinafter, referred to as “AC color registration deviation”). That is, in the above-described conventional color image forming apparatus, the rotation fluctuation of the rotating body such as the photosensitive drum or the belt drive roll is detected by using the encoder attached to the rotating shaft of the photosensitive drum or the like, and is detected by the encoder. The rotation fluctuation of the photoconductor drum or the like is fed forward or fed back to the drive motor to reduce the rotation fluctuation of the photoconductor drum or the like. However, even if the control for reducing the rotation fluctuation of the photosensitive drum or the like is performed as described above, the eccentricity of the photosensitive drum itself or the eccentricity of the surface of the photosensitive drum due to the mounting thereof, the eccentricity of the reduction gear and the transmission gear, and the gear The eccentricity of the shaft and the eccentricity due to the clearance error of the rotating shaft of the photosensitive drum, the belt drive roll, and the like exist, and there is a problem that the image quality is deteriorated due to the displacement of the AC color registration.

Nevertheless, in the case of the registration-registered image sampling correction method according to the above proposal, not only the AC component of such a color registration deviation is not subject to correction, but also the color registration deviation of the AC component is detected. At the moment it was impossible to do anything.

The present applicant has solved the above problem, and has proposed an image forming apparatus capable of detecting an AC component of a registration error and determining an abnormality of the registration error caused by the AC component. It has already been proposed (Japanese Patent Application No. 7-89)
No. 892).

However, in the case of the image forming apparatus according to this proposal, when detecting the AC component of the registration error, D
The detection pattern proposed for detecting the registration deviation of the C component with high accuracy is used as it is. Therefore, the AC component of the misregistration generated in the image forming apparatus is detected,
As information for performing advanced control such as correcting the detected AC component misregistration by feeding it back to the drive system of the photosensitive drum or the transfer belt to correct the AC color misregistration, the resolution and precision of data are used. From the point of view, there was a problem that it was not enough.

More specifically, a detection pattern for detecting the registration shift of the DC component is as shown in FIG.
The intervals between the color misregistration detection patterns of the respective colors are set wide, and the registration misregistration of the AC component obtained by detecting the color misregistration detection patterns of the respective colors is limited to a vibration component having a very low frequency. On the other hand, A generated in the image forming apparatus
The C component includes various frequencies such as a cycle of one rotation of the photoconductor drum, a cycle of one rotation of the drive roll of the transfer belt, a vibration component of a gear driving them, an eccentric component, and a walk of the transfer belt. There are fluctuation factors and some of them have high frequencies that fluctuate in a short cycle. For this reason, the registration deviation of the AC component detected as described above hardly includes information on the rotation fluctuation of the drive system such as the photosensitive drum and the transfer belt, and the rotation of the drive system such as the photosensitive drum and the transfer belt is not included. There is a problem that the predetermined control cannot be performed by accurately detecting the fluctuation.

Further, in order to meet the demand for higher image quality in the above-mentioned conventional color image forming apparatus, when the color registration misregistration is to be suppressed to a high precision, for example, 70 μm or less,
Active control is performed to reduce the absolute amount of DC component and AC component misregistration, detect rotation fluctuations of the drive system such as the photosensitive drum and transfer belt as needed, and cancel the effect of the AC component misregistration. When executed, a technique for reducing the AC component is required. However, in the above-described conventional color image forming apparatus, it is not possible to accurately detect a displacement of the AC color registration caused by a rotation fluctuation of a driving system such as a photosensitive drum or a transfer belt, and therefore, it is necessary to improve the accuracy of the color registration. There was also a problem that it was not possible.

Further, in order to accurately detect the registration deviation of the AC component generated in the color image forming apparatus, according to the sampling theorem, the AC component is measured at a frequency originally higher than the vibration component generated in the color image forming apparatus. However, the color image forming apparatus has a vibration component having a considerably high frequency due to a driving gear or the like, and in order to detect the vibration component, a very fine color misregistration detection pattern must be formed with high accuracy. In addition, in order to sample the color misregistration detection pattern formed on the transfer belt, a physical size such as the width and length of the color misregistration detection pattern or the color misregistration detection pattern must be used. There is also a problem that the pattern for detecting color misregistration cannot be formed at a high frequency, that is, at an extremely small interval, due to a processing time of data for detecting the color shift. .

Incidentally, the sampling theorem is defined as “time t
When the frequency component of the signal f (t) which is a function of is limited to W hertz or less, the signal value f (i / 2W) (i = 1, 2,...) Measured at a time interval of 1/2 W From the signal f
Theorem is that (t) can be completely restored. In other words, the sampling frequency must be at least twice the maximum frequency of the spectrum distribution of the original signal to reproduce the original signal from the sampled data. It is. "

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to form a color misregistration detection pattern under limited conditions. However, it is possible to accurately detect the displacement of the AC color registration, and to actively control the driving system of the rotating body such as the photosensitive drum and the transfer belt, and to provide sufficient data as information for reducing the displacement of the AC color registration. An object of the present invention is to provide an image forming apparatus that can be obtained.

[0022]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a hyperlink "http: //www.ipdl.jpo-
miti.go.jp/Tokujitu/tjitemdrw.ipdl?N0000=235&N0500
= 9E # N / ;? 6 =?;? 78 /// & N0001 = 24 & N0552 = 9 & N0553 = 000003 "
\ t "tjitemdrw" As shown in FIG. 1, the transfer material 02 carried on the endless carrier 01 which is driven to rotate or a plurality of images having different colors are directly formed on the endless carrier by a plurality of image forming means. An image is formed by forming the image by using 03K, 03Y, 03M, and 03C, and a pattern for detecting color misregistration is formed by the color misregistration correction unit 04 on the endless carrier 01 that is driven to rotate. An image forming apparatus configured to perform a predetermined control operation by sampling a misregistration detection pattern is provided with a misregistration detection pattern 05 for detecting a periodic rotation fluctuation generated in the image forming apparatus. And its color shift
As a detection pattern,
Multiple messages with different pattern intervals
It is configured to have the following pattern .

Further, the image forming apparatus according to claim 2 of the present invention, rolling is carried on the endless carrier member is rotated
A plurality of images having different colors are directly placed on the copying material or the endless carrier.
Forming an image by forming an image
A pattern for detecting color misregistration is provided on the endless carrier that is rotationally driven.
Pattern and sample these color misregistration detection patterns.
An image configured to perform a predetermined control operation by ringing
Forming a periodic image generated in the image forming apparatus.
Color misregistration detection pattern to detect
In addition, only one pattern of the color misregistration detection is provided, and the single color misregistration detection pattern is sampled at a plurality of sampling frequencies.

Further, in the image forming apparatus according to the present invention, the color misregistration detection patterns are separately formed at at least two places in a direction perpendicular to the moving direction of the endless carrier, and the respective detection patterns are separately formed. May be configured to perform sampling.

[0025] Furthermore, the image forming apparatus of the present invention is to form a serial color misregistration detecting patterns in the central portion in the direction perpendicular to the moving direction of the endless carrier member, and configured to sample the detection pattern You may .

The image forming apparatus according to a third aspect of the present invention is an image forming apparatus, comprising: a roller supported on a rotatably driven endless carrier;
A plurality of images having different colors are directly placed on the copying material or the endless carrier.
Forming an image by forming an image
A pattern for detecting color misregistration is provided on the endless carrier that is rotationally driven.
Pattern and sample these color misregistration detection patterns.
An image configured to perform a predetermined control operation by ringing
Forming a periodic image generated in the image forming apparatus.
Color misregistration detection pattern to detect
In addition, the interval between the color misregistration detection patterns in the moving direction of the endless carrier is set in accordance with the frequency of the periodic rotation fluctuation generated in the image forming apparatus.

Further, the image forming apparatus according to claim 4 of the present invention, rolling is carried on the endless carrier member is rotated
A plurality of images having different colors are directly placed on the copying material or the endless carrier.
Forming an image by forming an image
A pattern for detecting color misregistration is provided on the endless carrier that is rotationally driven.
Pattern and sample these color misregistration detection patterns.
An image configured to perform a predetermined control operation by ringing
Forming a periodic image generated in the image forming apparatus.
Color misregistration detection pattern to detect
In addition, the frequency for sampling the color misregistration detection pattern is set in accordance with the frequency of the rotation fluctuation to be detected among a plurality of periodic rotation fluctuations generated in the image forming apparatus. Have been.

The image forming apparatus according to a fifth aspect of the present invention is an image forming apparatus, comprising: a roller supported on a rotatably driven endless carrier;
A plurality of images having different colors are directly placed on the copying material or the endless carrier.
Forming an image by forming an image
A pattern for detecting color misregistration is provided on the endless carrier that is rotationally driven.
Pattern and sample these color misregistration detection patterns.
An image configured to perform a predetermined control operation by ringing
Forming a periodic image generated in the image forming apparatus.
Color misregistration detection pattern to detect
In addition, the frequency at which the color misregistration detection pattern is sampled is set in accordance with a high-frequency rotation fluctuation among a plurality of periodic rotation fluctuations generated in the image forming apparatus. .

Further, in the image forming apparatus of the present invention, the color misregistration detection pattern is formed by repeating the pattern at predetermined intervals along the moving direction of the endless carrier, and A pattern formed along the direction perpendicular to the direction of movement of the endless carrier, and a pattern formed along the direction perpendicular to the direction of movement of the endless carrier. May be configured to be divided and sampled.

Further, the image forming apparatus according to the present invention may be configured so that the color misregistration detection pattern is divided and sampled for each color.

Further, according to a sixth aspect of the present invention, in the image forming apparatus according to the first or second aspect , the different color misregistration detecting patterns are provided in a direction orthogonal to the moving direction of the endless carrier. Are separately formed in at least two places, and a predetermined control operation is performed using data obtained by separately sampling each of the detection patterns.

In the image forming apparatus of the present invention , the same type of color misregistration detection pattern is separately formed in at least two places in a direction orthogonal to the moving direction of the endless carrier, and each of the detection patterns is separately formed. it may be configured to be comprehensive after sampling utilizing the averaged data performs a predetermined control operation.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first or second aspect , a plurality of color misregistration detection patterns having different frequency characteristics are formed by setting a pattern interval. By extracting the vibration waveform component obtained by sampling with the low-frequency detection pattern from the vibration waveform component obtained by sampling with the high-frequency detection pattern, the vibration component related to the high-frequency rotation fluctuation is extracted. It is configured to

According to an eighth aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect , wherein a plurality of color misregistration detecting patterns having different frequency characteristics by setting a pattern interval are used. When performing the sampling and control operation using the at least one detection pattern having the lower frequency, the sampling and control operation is performed using the at least one detection pattern having the next lower frequency. And a control operation.

Further, according to a ninth aspect of the present invention, in the image forming apparatus according to the second aspect , a color misregistration detection pattern having a high frequency is formed and sampled, and the frequency is determined from the sampling data. A vibration component related to low-frequency rotation fluctuation is detected by extracting only a low vibration component, and a vibration component related to high-frequency rotation fluctuation is detected by subtracting a vibration component related to low-frequency rotation fluctuation from the sampling data. It is configured to

According to a tenth aspect of the present invention, in the image forming apparatus according to the first or second aspect , the sampling of the color misregistration detection pattern is performed by a DC color register immediately after the apparatus is turned on. It is configured to be performed after at least one of the coarse adjustment and the fine adjustment of the correction cycle is completed.

[0037]

The image forming apparatus according to the first aspect of the present invention is provided with a color misregistration detection pattern for detecting a periodic rotation fluctuation generated in the image forming apparatus. Even when the misregistration detection pattern is formed under limited conditions, the misregistration detection pattern may be formed in consideration of the periodic rotation fluctuation generated in the image forming apparatus. An AC color registration deviation can be accurately detected by a color deviation detection pattern for detecting a periodic rotation fluctuation generated in the image forming apparatus, and a driving system of a rotating body such as a photosensitive drum or a transfer belt can be used. Active control is performed, and sufficient data can be obtained as information for reducing the deviation of the AC color registration. Further, the image forming apparatus according to the present invention has the above-mentioned color misregistration.
It is configured to have a plurality of detection patterns.
Therefore, the periodic rotation fluctuation occurring in the image forming apparatus is
Even if there are multiple color misregistrations,
It can be detected with high accuracy by the use pattern.

On the other hand , the image forming apparatus according to a second aspect of the present invention has only one color misregistration detection pattern,
Since the single color misregistration detection pattern is configured to be sampled at a plurality of sampling frequencies, only one color misregistration detection pattern needs to be formed, and the color misregistration detection pattern can be easily formed. It can be carried out.

Further, in the image forming apparatus of the present invention, the color misregistration detecting patterns are separately formed at least at two or more positions in a direction orthogonal to the moving direction of the endless carrier, and the respective detecting patterns are separately formed. When sampling is performed in the image forming apparatus, periodic rotation fluctuations caused by different phases and amplitudes at both ends of the rotating body in the axial direction due to an eccentric component of the rotating body in the image forming apparatus,
Detection can be performed with high accuracy.

Further, the image forming apparatus according to the present invention is configured such that the color misregistration detection pattern is formed at a central portion in a direction perpendicular to the moving direction of the endless carrier, and the detection pattern is sampled . In such a case, a periodic rotation variation that occurs due to a difference in phase or amplitude at both ends in the axial direction of the rotating body due to an eccentric component or the like of the rotating body in the image forming apparatus is generated at the center in the axial direction of the rotating body. It is possible to easily and efficiently detect the signals in a state where they are averaged to some extent. For this reason, two ends such as both ends in the axial direction of the rotating body.
There is no need to form a detection pattern at a location or more, sample the pattern, and average the obtained data.

In the image forming apparatus according to a third aspect of the present invention, the interval between the color misregistration detection patterns in the moving direction of the endless carrier is determined by the frequency of the periodic rotation fluctuation generated in the image forming apparatus. , The periodic rotation fluctuation occurring in the image forming apparatus can be accurately detected by a color misregistration detection pattern adapted to the rotation fluctuation.

The image forming apparatus according to a fourth aspect of the present invention seeks to detect the frequency at which the color misregistration detection pattern is sampled from a plurality of periodic rotation fluctuations generated in the image forming apparatus. Is configured so as to correspond to the frequency of the rotation fluctuation that occurs, even if there are a plurality of periodic rotation fluctuations that occur in the image forming apparatus, a specific periodic rotation fluctuation can be accurately detected. Can be detected.

Further, in the image forming apparatus according to a fifth aspect of the present invention, the frequency at which the color misregistration detection pattern is sampled is set to a higher frequency among a plurality of periodic rotation fluctuations generated in the image forming apparatus. Since it is configured to be set corresponding to the rotation fluctuation, as can be seen from the sampling theorem, without detecting the rotation fluctuation with a high frequency,
Only rotation fluctuations with a low frequency can be detected.

Further, according to the image forming apparatus of the present invention, the color misregistration detecting pattern is formed repeatedly at predetermined intervals along the moving direction of the endless carrier, A pattern formed along the direction perpendicular to the direction of movement of the endless carrier, and a pattern formed along the direction perpendicular to the direction of movement of the endless carrier. Is divided and sampled, the moving direction of the endless carrier and the pattern in the direction orthogonal to the direction are separated and sampled, so that the direction along the moving direction of the endless carrier is Even when the pattern interval is small, sufficient data processing time can be secured.

In the image forming apparatus according to the present invention, when the color misregistration detection pattern is configured to be divided and sampled for each color, the interval between the patterns of each color can be set narrow. Even when the frequency of the periodic rotation fluctuation generated in the image forming apparatus is high, it can be accurately detected.

Further, in the image forming apparatus according to a sixth aspect of the present invention, different types of color misregistration detection patterns are separately formed at at least two places in a direction orthogonal to the moving direction of the endless carrier. Since a predetermined control operation is performed using data obtained by separately sampling each detection pattern, a plurality of types of periodic rotation fluctuations occurring in the image forming apparatus can be detected accurately and efficiently. it can be. Also, since the sampling data obtained at the same time has the same phase, it is very effective for subsequent data processing and use.

In the image forming apparatus of the present invention, the same kind of color misregistration detection pattern is separately formed in at least two places in the direction orthogonal to the moving direction of the endless carrier, and each of the detection patterns is separately formed. taken together after sampling when using the averaged data configured to perform predetermined control operation, such as an eccentric component of the rotating body in the image forming apparatus of the rotary body axis direction due It is possible to reliably and accurately detect periodic rotation fluctuations that occur at both ends with different phases, amplitudes, and the like, and perform an optimal control operation that takes such eccentric components and the like into consideration.

[0048] The image forming apparatus according to claim 7 of the present invention, samples to form a plurality of color shift detection patterns having different frequency characteristics by setting the pattern interval, and sampled at a higher detection pattern frequency By subtracting the vibration waveform component obtained by sampling with a low-frequency detection pattern from the vibration waveform component obtained by
Since the vibration component related to the high-frequency rotation fluctuation is configured to be extracted, the rotation fluctuation having a different frequency among the periodic rotation fluctuations generated in the image forming apparatus can be efficiently detected. In particular, when a plurality of color misregistration detection patterns having different frequency characteristics are sampled simultaneously, since the phase is the same, the subtraction of the vibration waveform component can be easily performed as it is, and more efficiency can be achieved. Good detection becomes possible.

In the image forming apparatus according to the eighth aspect of the present invention, when the sampling and control operation is performed using a plurality of color misregistration detection patterns having different frequency characteristics by setting the pattern interval, the frequency is low. At least one
It is configured to perform the sampling and control operation using one detection pattern and then perform the sampling and control operation using at least one detection pattern having the next lower frequency. The detection of the periodic rotation fluctuation of the high frequency to be performed is performed in a state where the rotation fluctuation of the lower frequency has already been eliminated, so that it can be easily and accurately performed.

The image forming apparatus according to a ninth aspect of the present invention forms a pattern for detecting color misregistration having a high frequency, performs sampling, and extracts only a vibration component having a low frequency from the sampled data to thereby reduce the frequency. Since it is configured to detect a vibration component related to low-speed rotation fluctuation, and to detect a vibration component related to high-frequency rotation fluctuation by subtracting the vibration component related to low-frequency rotation fluctuation from the sampling data, , A plurality of types of periodic rotation fluctuations can be efficiently detected.

[0051] Further, the image forming apparatus according to claim 1 0 of the present invention, the sampling of the color shift detection patterns, at least one of the coarse adjustment and fine adjustment of DC color registration correction cycle just after power-on of the device When the AC color registration deviation is detected, at least the coarse adjustment of the DC color registration correction cycle has been completed, so that the periodic rotation fluctuation generated in the image forming apparatus is completed. The color misregistration detection pattern for detecting the color misregistration can be formed with high precision, and it is possible to reliably prevent the occurrence of the overlap with the color misregistration detection pattern and the detection error of the AC color registration misalignment due to the pattern overlap. can do. Furthermore, if the sampling and correction cycle of the AC color misregistration detection pattern is performed between the coarse adjustment and the fine adjustment of the DC color registration correction cycle immediately after the power is turned on, the fine adjustment of the subsequent DC color registration correction cycle can be performed with high accuracy. Can do well.

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment.

FIG. 2 is an overall configuration diagram showing a digital color copying machine as an embodiment of the image forming apparatus according to the present invention.

In FIG. 2, an original 2 placed on a platen glass 1 is converted into RGB analog image signals by an image scanner equipped with a color CCD sensor 3 via a scanning optical system including a light source and a scanning mirror. Read. The RGB analog image signals read by the color CCD sensor 3 are converted into KYMC image signals by the image processing unit 4 and temporarily stored in a memory provided inside the image processing unit 4.

As shown in FIGS. 2 and 3, the image processing unit 4 outputs image forming units 5 for each color of black (K), yellow (Y), magenta (M), and cyan (C).
K, 5Y, 5M, 5C ROS (Raster Out)
put Scanner) 8K, 8Y, 8M, and 8C sequentially output image data of each color, and these ROS 8K,
Laser beams LB emitted from 8Y, 8M, and 8C according to image data are supplied to respective photosensitive drums 6K, 6K.
The surfaces of Y, 6M and 6C are scanned and exposed to form an electrostatic latent image. The electrostatic latent images formed on the respective photosensitive drums 6K, 6Y, 6M, 6C are developed by the developing units 9K, 9Y, 9M, 9C.
Thus, the toner image is developed as a toner image of each color of black (K), yellow (Y), magenta (M), and cyan (C).

Each of the photosensitive drums 6K, 6Y, 6M, 6
Transfer paper 1 for transferring toner images of each color formed on C
Reference numeral 4 denotes a plurality of paper feed cassettes 15 and 1 as shown in FIG.
The paper feed roller 18 and the paper transport roller pair 19, 20, 2,
1 is conveyed through a sheet conveyance path 22 composed of the first and second sheets. The transfer paper 14 supplied from any one of the paper feed cassettes 15, 16, 17 is sent out onto a transfer belt 24 as an endless carrier by a registration roll 23 which is rotated at a predetermined timing. This transfer belt 24
Is a drive roll 25 and a stripping roll 26
, A tension roller 27, and an idle roller 28, which are endlessly wound around with a constant tension and driven by a dedicated drive motor (not shown) having excellent constant speed. It is designed to circulate at a predetermined speed in the direction. As the transfer belt 24, for example, an endless belt is formed by forming a flexible synthetic resin film such as PET into a belt shape and connecting both ends of the synthetic resin film formed in a belt shape by means such as welding. What was formed in the shape is used.

The leading end of the transfer sheet 14 conveyed by the transfer belt 24 and the leading end of the image on the first photosensitive drum 6K formed by the first image forming unit 5K are
The paper feed timing and the image writing timing are determined so that they coincide at the lowest transfer point of the photosensitive drum 6K. Transfer paper 1 that has reached the transfer point
Reference numeral 4 denotes the transfer of the visible image on the photosensitive drum 6K by the corotron 11K for transfer, and furthermore, the photosensitive drum 6Y
To the transcription point directly below. This photosensitive drum 6Y
The transfer paper 14 that has reached the transfer point immediately below is transferred with the visible image on the photosensitive drum 6Y in the same manner as the transfer on the photosensitive drum 6K. Similarly, the transfer paper 14 after all the transfer is further conveyed by the transfer belt 24,
When reaching the vicinity of the stripping roll 26, the charge is removed by the stripping charge removing corotron 29 and the stripping roll 2 having a small radius of curvature is set.
The transfer belt 24 is separated from the transfer belt 24 by the stripper 6 and the separation claw 30. Thereafter, the transfer paper 1 on which the four color toner images are transferred
4 is fixed by a heating roller 32a and a pressure roller 32b by a fixing device 31, and is discharged onto a discharge tray 34 shown in FIG. 2 by a discharge roller pair 33 to copy a color image.

When a full-color image is copied on both sides of the transfer sheet 14, the transfer sheet 14 having a color image formed on one side is not directly discharged by the discharge roll pair 33 as shown in FIG. And switching plate 35
The transfer direction of the transfer paper 14 is switched downward by
The transfer paper 14 is again conveyed onto the transfer belt 24 through the paper conveyance path 22 in a state where the transfer paper 14 is turned upside down via a paper conveyance path 40 including a pair of paper conveyance rolls 36, 37, 38, 39, and the like. A color image is formed on the back surface of the transfer paper 14 by the same process as described above.

The above four image forming units 5K, 5Y, 5M, 5K, 5Y, 5M,
5C, all have the same configuration as shown in FIG. 3, and these four image forming units 5K, 5Y, 5M,
In 5C, as described above, black, yellow, magenta, and cyan color toner images are sequentially formed at a predetermined timing. The image forming units 5K, 5Y, 5M, and 5C for the respective colors include photoconductor drums 6K, 6Y, 6M, and 6C. After being uniformly charged by scorotrons 7K, 7Y, 7M and 7C, laser beams LB for image formation emitted from ROSs 8K, 8Y, 8M and 8C in accordance with image data are scanned and exposed to correspond to each color. An electrostatic latent image is formed. The photosensitive drums 6K, 6Y, 6
The electrostatic latent images formed on the surfaces of the image forming units M, 6C correspond to the developing units 9K, 9Y, 9 of the image forming units 5K, 5Y, 5M, 5C.
M and 9C develop visible toner images with toners of black, yellow, magenta and cyan colors, respectively, and these visible toner images are charged by pre-transfer chargers 10K, 10Y, 10M and 10C. After the transfer, the transfer paper 14 held on the transfer belt 24 by charging the transfer chargers 11K, 11Y, 11M, and 11C is transferred.
Are sequentially transferred. The transfer paper 14 onto which the toner images of the above-described black, yellow, magenta, and cyan colors have been transferred is separated from the transfer belt 24, and then subjected to the fixing process by the fixing device 31 as described above, thereby forming a color image. The formation takes place.

Further, the transfer paper 14 is supplied from any one of the plurality of paper feed cassettes 15, 16 and 17, is conveyed onto the transfer belt 24 at a predetermined timing by the registration rolls 23, and is used for holding the paper. Charger 41
In addition, the toner image is held and transported on the transfer belt 24 by the charging roller 42.

The photosensitive drums 6K, 6Y, 6
After the toner image transfer step is completed, the M and 6C are neutralized by the pre-cleaning neutralizers 12K, 12Y, 12M, and 12C, and are also cleaned by the cleaners 13K, 13Y, 13M, and 1M.
3C removes residual toner and the like, and prepares for the next image forming process.

The transfer belt 24 is used to transfer the transfer paper 1
After the roller 4 has been peeled off, the charge is removed by the transfer belt removing corotron pairs 43 and 44 in the orbit around the transfer belt, and the surface of the transfer belt 24 is
The cleaning device 47 including the blade 5 and the blade 46 removes toner, paper dust, and the like.

In the digital color copying machine constructed as described above, for example, the following device is used as a device for rotating the photosensitive drums 6K, 6Y, 6M and 6C. The photosensitive drums 6K, 6Y, 6
A device for rotating and driving M and 6C is provided for each photosensitive drum in a similar manner. Here, the photosensitive drum 6K will be described. As shown in FIG. 4, the drive device for the photosensitive drum includes a sub-frame 51 attached to a first frame 50 located on the front side of the copying machine main body, and a second frame arranged in parallel with the first frame 50. 52, the photosensitive drum 6K is rotatably supported, and the rotating shaft 5 of the photosensitive drum 6K is
Drive shaft 56 connected to coupling 4 via coupling 55
Is rotatably supported between the second frame 52 and the third frame 57. The photosensitive drum 6K includes a drive motor 58 and a rotation shaft 59 of the drive motor 58.
, A first intermediate gear 61 meshing with the motor shaft gear 60, a second intermediate gear 62 fixed to the same shaft as the first intermediate gear 61, and a second intermediate gear The photoreceptor drum 6K is rotatably driven by a photoreceptor drive gear 63 fixed to a drive shaft 56 of the photoreceptor drum 6K that meshes with 62. Further, the photosensitive drum 6
An encoder 64 is attached to the drive shaft 56 of K, detects the rotation state of the photosensitive drum 6K by the encoder 64, and feeds back a detection signal to the drive circuit 66 of the drive motor 58 via the control circuit 65. hand,
The rotation speed of the photosensitive drum 6K is controlled to be constant. In the drawing, reference numeral 67 denotes a flywheel attached to the rotating shaft 59 of the photosensitive drum 6K.

The drive roller 25 for rotating the transfer belt 24 is also driven to rotate by the same drive device as that for the photosensitive drum 6.

In the digital color copying machine constructed as described above, for example, the photosensitive drums 6K, 6Y, 6M, 6C
, The cycle of the drive roll 25 of the transfer belt 24, and the gears 60, 61, 62,
A relatively high-frequency rotation fluctuation that fluctuates in a short cycle occurs, such as a vibration component and an eccentric component of 63, a so-called walk or the like in which the transfer belt 24 moves in a direction orthogonal to the movement direction, and this is shown in FIG. And rotation fluctuations of black, yellow, magenta, and cyan.

FIG. 6 is a schematic diagram showing the image forming section of the digital color copying machine together with the control section.

In the figure, reference numeral 70 denotes each image forming unit 5
Transfer belt 2 formed by K, 5Y, 5M, 5C
4 is a color shift detecting pattern detecting means for detecting a color shift detecting pattern image 71 on the transfer belt 24. The pattern detecting means 70 is arranged in a pair at each end in the width direction in the image area of the transfer belt 24. Light source 73 and light receiving element 7
4 is provided. The light source 73 includes an LED for generating background light necessary for detecting the pattern image 71 for detecting a color shift on the transfer belt 24.
The light receiving element 74 is provided between the light source 73 and the transfer belt 24.
And a CCD as a line type light receiving element in which a large number of light receiving pixels are linearly arranged.

Reference numerals 75K, 75Y, 75M, and 75C denote ROS 8K in each of the image forming units 5K, 5Y, 5M, and 5C.
An interface board for sending image signals to 8Y, 8M, and 8C, and a correction board 76 for controlling a color misregistration correction system. Reference numeral 77 denotes a memory and an image processing board that collectively handles image processing relations, and 78 denotes a control board that manages all of these boards and the movement of the entire digital color copying machine.

FIG. 7 is a sectional view showing the pattern detecting means for detecting the color misregistration.

In the drawing, reference numeral 80 denotes a housing of the pattern detecting means, and 81 denotes a linear CC as the light receiving element 74.
D is a substrate on which a linear CCD 81 and peripheral circuits for driving the linear CCD 81 are mounted. The board 82 is attached to the housing 80 via an angle 83 having an L-shaped cross section. Reference numeral 84 denotes a gradient index lens array, and reference numeral 85 denotes a substrate on which an illumination light source 86 as the light source 74 and a peripheral circuit for driving the illumination light source 86 are mounted.

FIG. 8 is a three-dimensional view showing the positional relationship among the sensor substrate 82, the gradient index lens array 84, and the pattern image 71 for detecting the image position on the transfer belt 24. , Two pairs of the sensor substrate 82 and the gradient index lens array 84 shown here are arranged. Moreover, the housings 80 are arranged one at each end in the width direction in the image area of the transfer belt 24. The linear C attached to the one sensor substrate 82
The CD 81 is for detecting both the main scanning and sub-scanning directions of the color misregistration detection pattern 71 on the near side, and the linear CCD 81 attached to the other sensor substrate 82 is
This is for detecting those on the back side. As described above, by using two sensors, a shift in the main scanning direction near the center of the copy, a shift in the sub-scanning direction near the center of the copy, a magnification error in the main scanning direction, a shift due to an angular shift with respect to the main scanning direction, and the like. Can be adjusted in all directions. For example, if only adjustment in the main scanning direction is performed, only one detection sensor may be used. However, it is preferable to separately provide two or more detection sensors in the detection width direction. As shown in FIG. 6, two housings 80 each having the above-described two built-in sensors are provided at both ends in the width direction of the image area of the transfer belt 24.

Further, as the illumination light source 86, LE
When D is used and a required illumination range cannot be secured with one LED, a plurality of LEDs may be used. For example, when one sensor CCD 81 detects the scanning start position of the laser beam scanning device, that is, the shift in the main scanning direction and the transfer conveyance direction, that is, the shift in the sub-scanning direction, at relatively close positions, one LED 86 is used. When detecting at a distant position, two LEDs are assigned. At this time, by bringing the condensing type LED 86 closer to the transfer belt 24, an illumination width almost equal to the outer shape of the LED can be obtained, and the number of LEDs to be turned on is several, so that the power consumption thereof can be extremely reduced.

In this embodiment, a transparent belt 24 made of, for example, PET (polyethylene terephthalate) is used as the transfer / transporting means.
Is formed in an endless belt shape by connecting both ends of a PET film formed in a belt shape by means such as welding. As shown in FIG. 9, the typical transmittance of the transfer conveyance belt 8 is such that the transmittance increases as the wavelength increases. FIG. 10 shows typical sensitivity characteristics of the CCD 31. The CCD 31 has good sensitivity in the visible light region. On the other hand, the emission wavelength of the LED 86 from which high luminance is obtained is in the red region (600 to 700 nm), and by combining these, a large sensor output can be obtained. When the pattern image 71 on the transfer belt 24 reaches the detection position, the transmittance at the pattern position becomes 0 because the toner forming the pattern image 71 is opaque regardless of the color.
And the sensor output becomes very small. The greater the difference between the sensor outputs, the more stable the detection is. The output example of this configuration is shown in FIG. 11, and almost the same output is obtained for each color of KYMC.

For example, as shown in FIG. 12, the DC color misregistration detecting pattern 71 is in the sub-scanning direction for detecting a main scanning direction misalignment which is a direction orthogonal to the traveling direction of the transfer belt 24. Color shift detection pattern 71b
(K), 71b (Y), 71b (M), 71b (C)
And color shift detection patterns 71a (K), 71a (Y), 71a (M), 7 along the main scanning direction for detecting a shift in the sub-scanning direction, which is the traveling direction of the transfer belt 24.
1a (C) is used. Then, as shown in FIG. 6, a predetermined position 71 a is located on the transfer belt 24 at a predetermined position which can be read by the pattern detecting means 70 for detecting color misregistration, which is disposed one by one on the front side and the back side of the image forming unit. (K), 71a (Y), 71a (M), 7
1a (C), 71b (K), 71b (Y), 71b
(M) and 71b (C) are multiplex-transferred one set at a time. Further, the color misregistration detection patterns 71a (K), 71a (Y), 71 in the main scanning direction and the sub-scanning direction are used.
a (M), 71a (C) and 71b (K), 71b
(Y), 71b (M), and 71b (C) are formed by forming a band pattern as a linear portion of each color of black (K), yellow (Y), magenta (M), and cyan (C) at predetermined intervals. They are arranged sequentially.

FIG. 13 is a block diagram showing one embodiment of the control section of the sampling apparatus for the color misregistration detection pattern according to this embodiment. This control unit includes a correction board 7 shown in FIG.
6.

In this correction substrate 76, a driver 91 drives a CCD sensor according to a clock generated by a CCD drive clock generation circuit 90, and sequentially reads read image data of, for example, 8 bits and 256 gradations in pixel units to a receiver 92. take in. Then, the image data relating to the main scanning is stored in the main scanning high-speed image memory 94 through the bus control system 93, and the image data relating to the sub-scanning is averaged by the sub-scanning image operation circuit 95. The image data is stored in the sub-scanning high-speed image memory 96 through the line 93. The sample timing control circuit 97 acquires image data into the sub-scanning image arithmetic circuit 96, the main scanning high-speed image memory 94, and the sub-scanning high-speed image memory 99 according to the sample start timing, the sampling period, and the like set by the CPU 98. Is controlled. The main RAM 100 is used as a work area of the CPU 98, and the ROM 101 stores a control program of the CPU 98. Serial communication IC10
2. The serial communication driver 103 includes various control systems 104
The CPU 98 transmits control data such as setting parameters to the I / O interface 105.
Is for outputting on / off signals to various correction systems 104, inputting on / off signals from sensors, and transmitting / receiving on / off signals to / from the system controller 106. The serial communication driver 107 includes the CPU 98 and the system controller 1
06 is transmitted and received.

The CPU 98 controls the CCD drive clock generation circuit 90, the sample timing control circuit 97, and the bus control system 93 to fetch the image data of the registration deviation measurement pattern 71 output on the transfer belt 24 and to set the image position address. After the registration, the registration shift amount is calculated, and the serial communication IC 1
02, the various correction systems 104 are controlled through the serial communication driver 103 or the I / O interface 105 and the serial communication 107.

In this embodiment, a color misregistration detection pattern dedicated to AC component detection for detecting the periodic rotation fluctuation generated in the digital color copying machine is a DC
It is configured so as to be provided separately from the pattern for detecting color registration deviation.

That is, in this embodiment, FIG.
As shown in FIG. 5, K, formed on the transfer belt in a straight line in the main scanning direction to detect rotation fluctuation in the sub-scanning direction.
Y, M, C four color patterns 110a (K), 110a
(Y), 110a (M), and 110a (C) are formed in parallel with each other at a constant fine pitch in the sub-scanning direction, and detect rotation fluctuations in the main scanning direction.
K, Y, M, C linearly formed in the sub-scanning direction
4b patterns 110b (K), 110b (Y), 1
10b (M) and 110b (C) are configured to form one set along one straight line in the sub-scanning direction. These AC color shift detection patterns 110a (K), 110
a (Y), 110a (M), 110a (C) and 110
b (K), 110b (Y), 110b (M), 110b
(C) is formed continuously along the moving direction of the transfer belt 24 (for example, all around the transfer belt 24) and is sampled. In addition, as shown in FIG.
In order to detect rotation fluctuations in the main scanning direction, patterns 110b (K), 110b (Y), 110b (M) of four colors of K, Y, M, and C formed linearly along the sub-scanning direction.
110b (C) may be formed long in parallel with each other along the sub-scanning direction.

Of the color shift detection patterns dedicated to AC component detection, patterns 110a (K), 110a (Y), and 110a for detecting rotation fluctuation in the sub-scanning direction.
a (M) and 110a (C), as shown in FIG. 14A, the interval P in the moving direction of the transfer belt 24 corresponds to the frequency of the periodic rotation fluctuation generated in the digital color copying machine. Is set. At that time, the frequency of the periodic rotation fluctuation generated in the digital color copier is:
As described above, the photosensitive drums 6K, 6Y, 6M, 6C
, One cycle of the drive roll 25 of the transfer belt 24, vibration components and eccentric components of gears that drive them, and walks of the transfer belt 24, and various other frequency components. Therefore, detecting all of these frequencies at once requires a very high sampling frequency. However, in practice, it is impossible to form a pattern corresponding to a very high sampling frequency due to the relationship between the pattern width, the calculation time, and the like.

Therefore, in this embodiment, a plurality of AC component detection dedicated patterns are provided, and a frequency to be detected is assigned to each AC component detection dedicated pattern. This makes it possible to obtain a high AC color registration deviation detection accuracy while suppressing the sampling frequency. However, the present invention is not limited to this. As will be described later, only one AC component detection dedicated pattern is formed corresponding to a relatively high sampling frequency, and is determined using this one AC component detection dedicated pattern. Of course, it may be configured to detect a plurality of AC components.

When the AC component is detected, it becomes more difficult to obtain the number of repetitive samples at a lower frequency due to the time required for the detection. Therefore, there is a problem how to improve the accuracy of low frequency sampling. now,
Assume that multiple ACs in a digital color copier system
It is assumed that the vibration frequencies are A, B, and C (A>B> C). When the low frequency C is detected, the sampling frequency is deliberately set to the high frequency A or B itself or its divisor, and when there is no problem in the sampling of C, as shown in FIG. It is set to sample together. For example, A = 30 Hz, B
= 20Hz, C = 3Hz, sample frequency is 10
Hz. On the other hand, if there is a problem, the sampling frequency is set to a frequency which is more susceptible to accuracy or a divisor thereof. For example, A = 30 Hz, B = 5H
When z and C = 3 Hz, the sampling frequency is set to 10 or 15 or 30 Hz. At this time, it is difficult to separate B and C unless the amplitude of either vibration component B or vibration component C is small. For example, the amplitude of vibration component B is smaller than the amplitude of vibration component C. In this case, the vibration component B can be ignored, and only the vibration component C can be detected.

By setting the sampling frequency in this manner, as shown in FIG. 16, the vibration components of the frequencies A and B can be made dead zones, so that the detection and analysis of only the vibration component C can be easily performed. And the sample accuracy can be improved.

Based on the above theoretical considerations, in this embodiment, the frequency for sampling the color misregistration detection pattern dedicated to AC component detection is determined by changing the frequency of a plurality of periodic rotation fluctuations generated in the digital color copying machine. Of these, the setting is made so as to correspond to the high-speed rotation fluctuation.

Now, the rotational frequency of the photosensitive drum 6 is set to 0.
Assuming that the rotation frequency of the drive roll 25 of the transfer belt 24 is 5 Hz, the sampling frequency of the color misregistration detection pattern 110 dedicated to AC component detection is 5 Hz, which is equal to the rotation frequency of the drive roll 25 of the transfer belt 24 having a high frequency. Is set to As a result, the process speed of the digital color copying machine was increased to 160 mm / sec.
Assuming that c, patterns 110a (K), 110a (Y), 110a for detecting rotation fluctuation in the sub-scanning direction among the color shift detection patterns 110 dedicated to AC component detection.
14 (M) and 110a (C), as shown in FIG. 14, the interval P between patterns of the same color in the transfer belt moving direction 24 is, for example, 160 (mm / sec) ÷ 5 (Hz) =
The distance p is set to 32 (mm), and the interval p between adjacent patterns having different colors is set to 8 mm. However, it is not limited to this, and the sample frequency is set to 5 Hz.
When the frequency is a half of 2.5 Hz, the interval P between patterns of the same color may be set to about 64 mm.

In the color image forming apparatus according to this embodiment having the above configuration, even if the color misregistration detection pattern is formed under limited conditions as described below, the AC color registration misregistration is performed. Can be accurately detected, and the driving system of the rotating body such as the photosensitive drum and the transfer belt can be actively controlled, and sufficient data can be obtained as information for reducing the deviation of the AC color registration. I have.

That is, in the above-described digital color printer, the position and size of each image forming unit itself, and further, each image forming unit 5K, 5Y, 5
The position and size of the components in the M and 5C may change slightly. Of these, changes in the internal temperature and external forces are inevitable.For example, daily work such as clearing paper jams, replacing parts due to maintenance, and moving the digital color printer requires applying external force to the digital color printer. Becomes When a change in the internal temperature or an external force acts on the digital color printer, the alignment of the images formed by the image forming units 5K, 5Y, 5M, and 5C for each color deteriorates, and a DC-like color registration shift occurs. Therefore, it is difficult to maintain high image quality.

In the digital color printer, for example, one cycle of the photosensitive drum 6, one cycle of the drive roll 25 of the transfer belt 24, a vibration component and an eccentric component of a gear driving the transfer belt 24, a transfer belt, and the like. There is also a relatively high frequency AC-like color registration shift that fluctuates in a short cycle, such as 24 walks.

By the way, in the digital color printer, in order to meet the demand for higher image quality, it is necessary to suppress the color registration deviation to a high precision, for example, about 70 μm or less. To this end, by improving the manufacturing accuracy of the image forming unit and the transfer belt itself and the accuracy of the driving device, etc., the absolute amount of the color registration deviation of the DC component and the AC component can be reduced, and the photosensitive drum, the transfer belt and the like can be reduced. The rotation fluctuation of the drive system is detected at any time,
In some cases, it is necessary to perform active control so as to cancel the influence of the color registration deviation of the AC component.

Therefore, in the above-described digital color printer, when the apparatus is turned on, after a paper jam is recovered, and at a predetermined timing, before the start of the normal image forming mode (print mode) or in the normal image forming mode (print mode). Mode), a sampling operation of a DC color misregistration detection pattern and a correction mode based on the sampling operation as necessary.
In addition, a sampling operation of the AC color misregistration detection pattern and a predetermined operation based thereon are performed. At this time, the sampling operation of the AC color shift detection pattern and the predetermined operation based on the same may be executed each time the DC color shift detection pattern is sampled and the correction mode based thereon is performed. It is set such that the sampling operation of the AC color shift detection pattern and the predetermined operation based thereon are performed only once in the color shift correction cycle immediately after the power of the apparatus is turned on.

Further, in this embodiment, as shown in FIG. 17, it is first determined whether or not to execute a color shift correction cycle (step S10). A detection coarse adjustment pattern sample is performed (step S11). Here, the color misregistration detection coarse adjustment pattern has a larger pitch than the DC color misregistration detection pattern 72 shown in FIG. 12, and is used for coarse adjustment of the DC color misregistration. In this color shift detection coarse adjustment pattern sample, sample data of the coarse adjustment pattern is taken in, and the sampling data is calculated to determine the image position. When the image positions for all the sampling data are obtained, the correction values of the various DC registers are calculated (step S12), the correction values of the various DC registers are set (step S13), and the correction values of the various DC registers are set. When the setting is completed, this is transmitted to the system board by communication (step S14).

Next, as described later, the transfer belt 2
After the detection and calculation of the color misregistration detection pattern 110 dedicated to the detection of the AC component formed on the P.4 (step S1)
5), a color shift detection fine adjustment pattern sample is performed (step S16). Here, the color misregistration detection fine adjustment pattern 72 is
This is shown in FIG. 12, and is for fine adjustment of DC color shift. In the color shift detection fine adjustment pattern sample, sample data of a fine adjustment pattern is taken in, and the sampling data is calculated to obtain an image position. When the image positions for all the sampling data are obtained, the correction values of various DC registers are calculated (step S1).
7) Set the correction values of various DC registers (step S1)
8) When the correction value setting of the various DC registers is completed, the correction value is transmitted to the system board by communication (step S19),
End the correction cycle.

At this time, if the AC component detection / correction cycle is executed immediately after the power of the apparatus is turned on and before the coarse adjustment of the DC color registration correction cycle is completed, there is a variation in the DC color registration. If the sample period is shortened, patterns of other colors before and after may overlap, and if a large sample area is not used at the time of sampling, there is a risk that the pattern will not enter the sample area. Because sample is not possible,
The pattern interval cannot be reduced. On the other hand,
At least after the end of the coarse adjustment in the DC color registration correction cycle, the variation in the DC color registration becomes small, so that the pattern interval can be reduced. Also, when performing DC color registration correction, DC component detection accuracy is higher when sampling is performed with a small amount of AC components than when sampling is performed with a large amount of AC components remaining. Therefore, it is preferable to complete the correction of the AC component before making the fine adjustment. Thus, preferably, by inserting the AC color registration correction cycle between the coarse adjustment and the fine adjustment of the DC color registration correction cycle,
In the fine adjustment of the DC color registration correction, the influence of the AC component can be reduced, and more accurate DC color registration correction can be performed.

Next, the sampling operation of the AC color misregistration detection pattern and the control operation based thereon will be described in detail.

First, in the sampling operation of the AC color misregistration detection pattern and the control mode based thereon, as shown in FIG. 6, a command is issued to each unit by the control board 78, and each interface board 75K, 75Y, 7
The image forming units 5K, 5Y, 5M, 5M, and 75C respectively correspond to the image data of the AC color shift detection pattern 110 by the built-in color shift detection pattern output means.
Start outputting sequentially to 5C. At this time, the timing at which each of the interface boards 75K, 75Y, 75M, and 75C starts outputting image data is exactly the same as the timing in the normal image forming mode (print mode). Thereby, each image forming unit 5K, 5Y, 5M, 5C
Forms a predetermined color misregistration detection pattern 110 based on the image data, sequentially multiplex-transfers it to the transfer belt 24 at the same timing as in a normal image forming mode (print mode), and forms the color misregistration detection pattern 110 Is formed on the transfer belt 24.

In the subroutine for detecting and calculating the color shift detection pattern 110 dedicated to AC component detection, sample data of the color shift detection pattern 110 dedicated to AC component detection is fetched as shown in FIG. S20) When the sampling frequency is calculated, the vibration frequency component, amplitude, and phase of the AC registration deviation of each color are detected (step S21), and the vibration frequency component, the amplitude, and the like of the AC registration deviation for all the sampling data are obtained. Calculate the correction values of the various AC registers (step S2
2) Correction values of various AC registers are set (step S2)
3) When the correction values of the various AC registers are set, the correction values are transmitted to the system board by communication (step S24).
The correction cycle of the AC cash register ends.

Next, a specific example of a color misregistration detection pattern dedicated to AC component detection and a correction algorithm will be described.

In the sampling of the color shift detection pattern 110 dedicated to the AC component detection, as shown in FIG.
Wait for the pattern writing to start (step S
101), light amount correction and shading correction are performed (steps S102 to S103), and sample start / end addresses of K data in the sub-scanning direction are set (step S10).
4).

Then, the process waits until a sample end interrupt of K data occurs (step S105), and stores the sampling data (K data) in the sub-scanning direction in the main RAM 10.
The block is transferred to 0 (step S106).

Subsequently, after setting the sample start / end addresses of the Y data in the sub-scanning direction (step S107),
The image position of the K data in the sub-scanning direction is calculated (step S
108).

Next, as shown in FIG. 20, it waits until a sample end interrupt of Y data occurs (step S1).
13), sampling data in the sub-scanning direction (Y data)
After block transfer to the main RAM 50 (step S
114), the sample start / end addresses of the M data in the sub-scanning direction are set (step S115), and the image position of the Y data in the sub-scanning direction is calculated (step S116).

Next, as shown in FIG. 21, the process waits until an M data sample end interrupt occurs (step S11).
9) Then, similarly, the processing up to the C data is performed as shown in FIGS. 21 to 22 (steps S120 to S13)
1) Return to step S105 until the specified number of samplings are completed, and repeat the same processing. When the specified number of samplings are completed (step S132), average calculation of the sampled data is performed (step S13).
4).

In the sub-scanning sample start point correction, as shown in FIG. 23, first, a nominal design sample address of each color is set (step S141), and the process waits until the end of the sample (step S142), and an image position of each color is calculated. (Step S143). The same processing is repeatedly performed until the sample is completed for K, Y, M, and C (step S144).

Next, the shift amount Δ of the K image position address from the center of the previous K sample range is calculated (step S145). If the image position address could not be determined because the previous sample was dirty due to dirt or the like, the correction value is used two times before, and if it was not possible to determine the image position twice before, the correction value used two times before is used.

The next sample start / end address of a pattern perpendicular to the belt traveling direction of K (color shift detecting pattern in the sub-scanning direction) is calculated from (design value−shift amount Δ),
It is set (steps S146 to S147). And K
It waits for the end of the sample (step S148). However, if it is not necessary for the system, step S145 can be omitted. At this time, the sample start interval between K and K is constant.

Next, the image position of K is calculated as shown in FIG. 24 (step S149). And each color (Y, M,
The sample start and end addresses of C) are set (step S150), and the process waits for sample completion (step S15).
1). KY, YM, and MC are constant values. Accordingly, the correction of the deviation caused by the sampling method performed when detecting the AC component is performed in steps S145 to S1.
Since it is only necessary to uniformly correct the K sample range correction value corrected in 47, the number of calculation steps is reduced. Next, the image position of each color (Y, M, C) is calculated (step S15).
2).

Step S until the sample of Y, M, C is completed
The processing from step 150 is repeated (step S153), and the processing from step S145 is repeated until the specified number of samples is completed (step S154).

In the correction of the address error of each color with respect to K after sampling, as shown in FIG. 25, the pattern sample of each color (step S161) and the calculation of the image position address (step S162) are sequentially performed, and K, Y, M , C obtained for each sample pattern-(KY, Y
A correction value (set fixed value) of an error caused by fixing the -M, MC spread interval (step S164).
Correction of error by correcting the spread start point of K (K,
Image address obtained for each sample pattern of Y, M, and C)-(Spreading correction of K)

Image address obtained for each sample pattern of K, Y, M, and C— (correction value of error caused by mismatch between ROS write / CCD read frequency (set fixed value))
Is performed (step S165).

As a result, the absolute address of each color and each pattern is obtained, and by analyzing them, the AC component can be detected (step S166).

An ideal image profile when reading the AC registration deviation measuring pattern 110 is generally as shown in FIG. Then, the center of the pattern image is obtained by using the centroid method, and this operation is repeated to obtain an average, whereby an accurate image position address can be determined.

The sampling of the color misregistration detection pattern in the main scanning direction is performed in the same manner as described above.

By the way, the sampling data of the color misregistration detection pattern 110 dedicated to the detection of the AC component is used for the AC color misregistration detection pattern 110 of each color unless the color registration misregistration of the AC component occurs in the digital color copying machine. The interval should be a constant value, as shown in FIG. However, in an actual digital color copying machine, one cycle of the photosensitive drum 6, one cycle of the drive roll 25 of the transfer belt 24, a vibration component and an eccentric component of a gear driving them, and a transfer belt There are rotational variations over various frequency components, such as 24 walks. For this reason, the interval between the color misregistration detection patterns 110 of each color is set as shown in FIG.
As shown in FIG. 7, the color registration shift of the AC component that does not become a constant value and varies periodically occurs.

Therefore, in this embodiment, the main RAM 1
Based on the sampling data at the intervals of the color misregistration detection patterns 110 stored in 00, the vibration frequency component, amplitude, and phase of the AC registration misregistration of each color are detected (step S21). Here, to detect the vibration frequency component, amplitude, and phase of the AC registration shift of each color, first, interval data of the color shift detection pattern 110 of each color is sampled according to the sampling frequency, and shown in FIG. like,
Calculate the average value based on the following equation. Average value = Σ (f (X) / n) Here, Σ is taken from X _−n to X _n .

The color misregistration detection pattern 11 for each color is used.
The sampling data at intervals of 0 is shown in FIG.
As shown in (1), a rising zero-cross address and a falling zero-cross address where the average value data is zero are obtained, and from these rising and falling zero-cross addresses, the vibration frequency component and phase of the AC registration deviation of each color are obtained. At this time, the phase of the AC registration deviation of each color is obtained based on the phase of the black pattern. Further, the amplitude of the AC registration deviation of each color is obtained by obtaining the maximum value and the minimum value, and subtracting the minimum value from the maximum value.

When the vibration frequency component, amplitude, and the like of the AC registration deviation for all the sampling data are obtained, the correction data is calculated and the correction data is transmitted (step S24).

As described above, in the above-described embodiment, the color misregistration detection pattern 110 dedicated to AC component detection for detecting the periodic rotation fluctuation generated in the digital color copying machine.
Therefore, even when the color misregistration detection pattern 110 dedicated to the AC component detection is formed under limited conditions, the periodic rotation generated in the digital color copying machine can be performed. The color misregistration detection pattern 110 may be formed in consideration of the variation, and the color misregistration detection pattern 110 for detecting the periodic rotation variation generated in the digital color copying machine can reduce the AC color registration misalignment. The photoconductor drum 6 can be detected with high accuracy.
It is possible to actively control the driving system of a rotating body such as the transfer belt 24 and the like, and to obtain sufficient data as information for reducing the displacement of the AC color registration.

In this embodiment, the frequency at which the AC color misregistration detection pattern 110 is sampled is determined by the frequency of the rotational fluctuation to be detected among a plurality of periodic rotational fluctuations generated in the digital color copying machine. Is configured so as to correspond to the above, even if there are a plurality of periodic rotation fluctuations occurring in the digital color copying machine, it is possible to accurately detect a specific periodic rotation fluctuation. it can.

Further, in this embodiment, the frequency at which the color misregistration detection pattern 110 is sampled is made to correspond to a high-frequency rotation fluctuation among a plurality of periodic rotation fluctuations generated in the digital color copying machine. Since it is configured to set, as can be seen from the sampling theorem, it is possible to detect only low-frequency rotation fluctuation without detecting high-frequency rotation fluctuation.

Further, in this embodiment, the color misregistration detection pattern 110 is repeatedly formed at predetermined intervals along the moving direction of the transfer belt 24 and in a direction perpendicular to the moving direction of the transfer belt 24. The pattern formed along the moving direction of the transfer belt 24 and the pattern formed along the direction orthogonal to the moving direction of the transfer belt 24 are divided and sampled. Therefore, by separating and sampling the pattern in the direction of movement of the transfer belt 24 and the pattern in the direction orthogonal to the direction of the transfer belt 24, even if the interval between the patterns along the direction of movement of the transfer belt 24 is small, Sufficient data processing time can be secured.

In this embodiment, the sampling of the color misregistration detection pattern 110 is performed after at least one of the coarse adjustment and the fine adjustment of the DC color registration correction cycle immediately after the power of the apparatus is turned on. Therefore, when the AC color registration deviation is detected, at least the coarse adjustment of the DC color registration correction cycle has been completed, so that the color deviation for detecting the periodic rotational fluctuation occurring in the digital color copying machine is detected. Detection pattern 1
10 can be accurately formed, and it is possible to reliably prevent the color misregistration detection pattern 110 from being overlapped. Furthermore, if the sampling and correction cycle of the AC color misregistration detection pattern 110 is performed between the coarse adjustment and the fine adjustment of the DC color registration correction cycle immediately after the apparatus is turned on, the fine adjustment of the subsequent DC color registration correction cycle is performed. It can be performed with high accuracy.

In this embodiment, the same color misregistration detection is carried out by a total of two pattern detection means 70 (see FIG. 6) provided at the left and right ends in the width direction of the image area of the transfer belt 24. Patterns (color shift detection patterns dedicated to DC component and AC component detection) are simultaneously sampled, and an average of each sampled data obtained at both ends thereof is used as a final detection value.

Accordingly, in the above-described detection and calculation of the color shift detection pattern 110 dedicated to AC component detection, in actuality, in steps S20 to S22 shown in FIG. The sampling data is fetched (step S20), and the sampling data at the left and right ends are calculated to detect the vibration frequency component, amplitude, and phase of the AC registration deviation at both ends of each color (step S21). Then, when the vibration frequency components and amplitudes of the AC registration deviation are obtained for all the sampling data, the average values of the vibration frequency components and amplitudes at the left and right end portions are integrated, and the averaged value is used as the detection value. The correction values of various AC registers are calculated (step 22).

As another method relating to the above-described detection and calculation, the operations of steps S20 to S22 shown in FIG. , And a correction value may be calculated, and then the obtained left and right correction values may be averaged to obtain a detection value.

As described above, the same type of color misregistration detection pattern is formed in the direction perpendicular to the moving direction of the endless carrier (main scanning direction).
Are separately formed at least in two or more locations, and the respective detection patterns are separately sampled, and then predetermined control is performed by using the data obtained by averaging and integrating the data of each location. As described above, it is possible to accurately detect the eccentric component existing in the main scanning direction of the rotating body and perform appropriate control based on the detection.

First, in a cylindrical rotating body such as the photosensitive drum 6, the belt drive roll 25, etc., there is generally an eccentric component which appears due to a mechanical dimensional error in manufacturing. And this eccentric component is shown in FIG.
As illustrated in (a), when the rotation axis G of the rotating body is displaced in parallel to the center line X of the cylinder (the normal position of the rotation axis G), the eccentric component in the main scanning direction Since a uniform periodic vibration component appears at any position, even if the color misregistration detection pattern is sampled at a certain position in the main scanning direction, the eccentric component is reliably detected regardless of the sampling position. , It is possible to perform appropriate control based on the detected value. However, as shown in FIGS. 29 (b) to (d), the rotation axis G is shifted from the center line X of the cylinder by only one end (b).
Both sides are shifted (c), or the center line X
(D), the eccentric component appears as a periodic vibration component that differs depending on the position in the main scanning direction, so that the color misregistration detection pattern is shifted to a certain position in the main scanning direction. Just sampling in places,
In addition to not being able to reliably detect the eccentric component, in some cases, if control is performed based on the sampling data, appropriate control cannot be performed, and conversely, the vibration component (rotational fluctuation) of the rotating body deteriorates. This results in such a result.

For example, as shown in FIG. 30A, periodic vibration components (a plurality of components having the same amplitude peak value but different phases) at both left and right ends due to the eccentricity of a rotating body such as a photosensitive drum. Exists, and when only the information of the vibration component at the left end is detected, the vibration component at the left end is almost eliminated by the control, whereas the vibration component at the right end is before the correction by the control. In some cases, the amplitude peak of the vibration component increases and deteriorates (FIG. 2B). Further, as shown in FIG. 31A, there are periodic vibration components (a plurality of components having the same phase but different amplitude peak values) at both right and left ends due to the eccentricity of the rotating body such as the photosensitive drum. When only the information of the vibration component at the left end is detected, the vibration component at the left end is almost eliminated by the control, whereas the vibration component at the right end is too large to be corrected by the control. In some cases, the amplitude peak is increased and deteriorated as compared to before (b in the figure).

On the other hand, when control is performed by averaging data obtained by sampling the same color misregistration detection pattern at both ends in the main scanning direction as in this embodiment, the cycle of the rotating body is controlled. Since the vibration component due to a typical eccentric component (FIGS. 29b to 29d) is detected at both ends where the most prominent appears, such eccentric component can be detected accurately, and at one point in the main scanning direction. It is possible to surely avoid executing erroneous control that deteriorates as a result of performing control by sampling.

That is, when the eccentric components as shown in FIG. 30A are present at the left and right ends, an appropriate control based on the averaged value (zero in this example) of the sampling data at the left and right ends. Is executed, and FIG.
A correction result as shown in FIG. 2 is obtained. Therefore, control is performed such that one of the vibration components is worse than before the correction, as in the case of sampling at one place (FIG. 30B).
Will be avoided. Further, when the eccentricity component as illustrated in FIG. 31A is present at the left and right ends, the eccentricity component is based on a value obtained by averaging the sampling data at the left and right ends (in this example, the average value of the left and right amplitude peaks). The control is executed, and a correction result as shown in FIG. 33 is obtained. Therefore, the control (FIG. 31b) in which one of the vibration components becomes worse than before the correction as in the case of sampling at one place is avoided.

In this embodiment, the color misregistration detection patterns are separately formed in at least two places in the direction (main scanning direction) perpendicular to the direction of movement of the endless carrier, and these detection patterns are separately formed. Although the example in which the predetermined control is performed by using the data obtained by sampling the data at each location and averaging the data is shown in the present embodiment, in the present invention, the pattern for detecting the color misregistration is moved in the moving direction of the endless carrier. The same control may be performed using data obtained by sampling a detection pattern formed at a central portion in the direction orthogonal to the above (it may be at a substantially central position instead of a true central position). . This is performed on the assumption that AC vibration components generated at both left and right ends in the axial direction of a rotating body such as a photosensitive drum appear as averaged values at the center.

When the formation of the color misregistration detection pattern and the sampling of the pattern are adopted as described above, the pattern formation and the sampling need only be performed at one place, and the pattern formation is performed at the left and right ends. It is not necessary to average each sampled data as in the case of performing the detection. Therefore, it is possible to more easily and efficiently detect the AC vibration component generated due to the eccentricity of the rotating body, and it is possible to perform the control associated therewith.

Embodiment 2 FIG. 34 shows Embodiment 2 of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals and described.
In this embodiment, it is configured to have a plurality of AC color misregistration detection patterns. The plurality of AC color misregistration detection patterns 110a (K), 110a (Y),
10a (M), 110a (C) and 110b (K), 1
10b (Y), 110b (M), and 110b (C) are formed along the moving direction of the transfer belt 24 so that a plurality of periodic rotation fluctuations occurring in the digital color copying machine can be detected. The intervals between the patterns are set to be different from each other. Note that these AC color shift detection patterns 110a (K), 110a (Y), 11
0a (M), 110a (C) and 110b (K), 11
0b (Y), 110b (M), and 110b (C) are also continuously formed along the moving direction of the transfer belt 24 (for example,
Formed on the entire circumference of the transfer belt 24) and sampled.

As described above, the AC color shift detection pattern 1
By having a plurality of patterns 10, even if there are a plurality of periodic rotation fluctuations occurring in the digital color copying machine, these can be detected with a plurality of kinds of color misregistration detection patterns with high accuracy. Can be.

Embodiment 3 FIG. 35 shows Embodiment 3 of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals and described.
In this embodiment, the color misregistration detection pattern 110a
(K), 110a (Y), 110a (M), 110a
(C) and 110b (K), 110b (Y), 110b
(M) and 110b (C) are formed continuously for each color, and are divided and sampled for each color. Note that these AC color shift detection patterns 11
0a (K), 110a (Y), 110a (M), 110
a (C) and 110b (K), 110b (Y), 110
Also, b (M) and 110b (C) are formed continuously along the moving direction of the transfer belt 24 (for example, all around the transfer belt 24) and sampled.

As described above, the AC color shift detection pattern 1
10 is configured to be sampled by being divided for each color, so that the interval between the patterns of each color can be set narrow, and even when the frequency of the periodic rotation fluctuation generated in the image forming apparatus is high. This can be detected with high accuracy.

As shown in FIG. 36, the DC color shift detection pattern 72 and the AC color shift detection pattern 110a
(K), 110a (Y), 110a (M), 110a
(C) and 110b (K), 110b (Y), 110b
(M) and 110b (C) may be formed in combination, and these may be separately sampled. Note that these AC color shift detection patterns 110a
(K), 110a (Y), 110a (M), 110a
(C) and 110b (K), 110b (Y), 110b
(M) and 110b (C) are also formed continuously (for example, all around the transfer belt 24) along the moving direction of the transfer belt 24 and sampled.

In this embodiment, the AC color misregistration detection pattern 110 is formed continuously for each color and is sampled by dividing it for each color. When used, an AC component detection and correction cycle may be performed before fine adjustment.
It may be carried out before the coarse adjustment of the components.

Embodiment 4 FIG. 37 shows Embodiment 4 of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals and described.
In this embodiment, after the coarse adjustment in the DC color registration correction cycle is completed and before the fine adjustment, the sampling operation of the AC color misregistration detection pattern and the control operation based thereon are performed as follows. . That is, in this embodiment, the rough adjustment process and the fine adjustment process of the DC color registration correction cycle employ the same configuration as the process content (FIG. 17) shown in the above-described embodiment.
Detection and calculation of each color drum AC register in FIG. 17 (step S
The difference is that steps S30 to S34 shown in FIG. 37 are employed instead of 15).

First, after the coarse adjustment of the DC color registration correction cycle shown in steps S10 to S14 of FIG. 17 is similarly performed, new AC registration detection / calculation for each color is performed (step S30). It is determined whether there is a phase shift of the AC color register based on the calculation result (step S31). In this step S31, for example, whether the amplitude of each vibration component at the left and right ends of the rotating body in the same drive system is in the optimum state, It is also determined whether or not there is a deviation in the phase of the vibration component.

If there is a phase shift in step S31, after calculating an AC vibration component correction value for each color (step S32), the correction value is applied to each drive control for the photosensitive drum, belt drive roll, and the like. The information is transmitted to the substrate by communication (step S33). When the correction values of the various AC registers are completed, the correction values are transmitted to the system board by communication (step S34), and the correction cycle of the AC registers is completed. Then, after the completion of the correction cycle of the AC register, D shown in steps S16 to S19 in FIG.
Fine adjustment of the C color registration correction cycle is similarly performed.
On the other hand, if there is no phase shift in step S31, the DC registration correction cycle is not executed and the DC
Move on to fine adjustment of color registration correction cycle.

Further, in this embodiment, a color misregistration detection pattern 110 dedicated to AC component detection is formed at both right and left ends in the image area of the transfer belt, and the detection and calculation are performed. In the subroutine for detection and calculation when the same type of detection pattern 110 is similarly formed at both left and right end portions, as shown in FIG. Acquisition (step S40), calculation of each sampling data at the left and right ends, and detection of each vibration frequency component, amplitude, and phase of the AC registration deviation (step S4).
1) When the vibration frequency components, amplitudes, and the like of the displacements of the AC registers at the left and right ends are obtained, a total average value of the vibration frequency components, the amplitudes, and the like at the right end and the left end is calculated (step S42). End the correction cycle.

On the other hand, in a subroutine of detection and calculation in the case where different types of detection patterns 110 are formed at both left and right end portions, as shown in FIG. Acquisition (step S50), calculation of each sampling data at both left and right ends, detection of each vibration frequency component, amplitude, and phase of AC registration deviation (step S51), and vibration frequency of each AC registration deviation at left and right ends. When the components, amplitudes, and the like are obtained, the respective average values of the respective vibration frequency components and amplitudes at the right end and the left end are calculated (step S5).
2) End the correction cycle of the AC register. In this case, a plurality of different types of AC registration deviations can be simultaneously detected by a single sampling. For this reason, the sampling process can be minimized as compared with the case where the various types of AC registration deviations are detected one by one in a dedicated sampling cycle, which is effective in reducing the image forming start waiting time of the apparatus.

By detecting the same type or different types of color misregistration detection patterns at the left and right ends simultaneously, the obtained data such as the vibration frequency component and amplitude of the AC registration misregistration have the same phase. It can be used very effectively when analyzing data.

Embodiment 5 This embodiment is different from Embodiment 4 described above in that each color AC register detection /
In the calculation step (Step S30), an example is shown in which a plurality of types of AC vibration components having different frequencies are detected. FIG. 40 shows the AC register detection / calculation process of this embodiment. That is, when there are low-frequency and high-frequency vibration components, the pattern interval P is set such that the AC vibration component of the rotating body or the driving system having a low frequency determined at the time of designing the rotary driving system is detected. A pattern for color misregistration detection dedicated to an AC color register of a frequency and a high frequency having a pattern interval P set to detect an AC vibration component of a rotating body or a drive system having a high frequency determined at the time of designing a rotary drive system. And a color misregistration detection pattern dedicated to the AC color register is formed on each of the left and right ends in the main scanning direction of the transfer belt, and sampling is performed.

Description will be made assuming that there is an AC vibration component as shown in FIG. 41 (a). First, a low-frequency AC
A color misregistration detection pattern dedicated to a color register is fetched (step S60), and sampling data is calculated to detect a low frequency vibration frequency component, amplitude, and phase (step S61). At the same time, a high frequency AC color is detected. A color misregistration detection pattern dedicated to a cash register is captured (step S6).
2) The phase of the sampling data is detected using the zero phase (Z phase) of the encoder attached to the rotating body as a reference timing (step S63). FIG.
(B) shows a vibration waveform component read by the detection pattern with a low frequency, and (c) shows a vibration waveform component read by the detection pattern with a high frequency. Then, the low-frequency AC vibration component is obtained from the obtained high-frequency AC vibration component.
The vibration component is subtracted (step S64). This subtraction
Since the two detection patterns are sampled at the same time and have the same phase, the detection can be easily performed as it is. As a result, a vibration waveform component as shown in FIG. 41D is obtained, and the frequency component, amplitude, and phase of the high-frequency AC vibration component after the subtraction are detected (step S6).
5) End the correction cycle. The low-frequency pattern sampling and the high-frequency pattern sampling are performed in completely different steps, and after adjusting the phase relationship between the two sampled data, two kinds of high-frequency AC vibration components are detected through the above-described steps. May be.

For example, a case will be described in which AC vibration components of both the photosensitive drum having a rotation frequency of 0.5 Hz and the transfer belt drive roll having a rotation frequency of 3 Hz are detected.
First, in order to detect the AC vibration component of the photosensitive drum,
In order to eliminate the influence of the vibration component of the transfer belt drive roll, sampling is performed using a low-frequency color misregistration detection pattern set at the same frequency of 3 Hz as the rotation frequency of the drive roll, and the vibration frequency component, amplitude, etc. Detection is performed (steps S60 and S61). On the other hand, in order to detect the AC vibration component of the transfer belt drive roll, sampling is performed using a high frequency detection pattern set to a frequency 20 Hz sufficiently higher than the rotation cycle of the drive roll, and the vibration frequency component and amplitude are measured. Are detected (steps S60 and S61). And
Since these two sample data are sampled simultaneously and have the same phase, the AC vibration component (amplitude and the like) of the same frequency 3 Hz depending on the photosensitive drum is directly subtracted from the AC vibration component of the frequency 20 Hz (step S64).
As a result, an AC vibration waveform mainly involving the transfer belt drive roll, in which the influence of the vibration component of the photosensitive drum is eliminated (FIG. 41D), is obtained. The amplitude and phase can be easily obtained.

Embodiment 6 This embodiment is different from the embodiment 4 described above in that each color AC register detection /
This shows another example in which a plurality of types of AC vibration components having different frequencies are detected in the calculation step (step S30). FIG. 42 shows the AC register detection / calculation process of this embodiment. That is, when there are low-frequency and high-frequency vibration components, a color misregistration detection pattern dedicated to a low-frequency AC color register and a high-frequency AC color register in which the interval P is set in the same manner as described in the fifth embodiment. Using a dedicated color misregistration detection pattern, 2
One AC vibration component is detected.

Description will be made on the assumption that there is an AC vibration component as shown in FIG. 43 (a). First, a low-frequency AC
A color misregistration detection pattern dedicated to the color register is fetched (step S70), the sampling data is calculated, and the low frequency vibration frequency component, amplitude, and phase are detected (step S71). A low-frequency AC vibration component correction value is set based on the
72). Next, after the control correction based on the correction value is performed, a high-frequency color misregistration detection pattern dedicated to the AC color register is fetched (step S73), and the sampling data is calculated to calculate the high-frequency vibration frequency component, amplitude, and phase. Is detected (step S74). During the sampling of the high-frequency pattern, the influence of the low-frequency vibration component is eliminated by correction, so that the high-frequency AC vibration component can be easily and accurately detected.

For example, a case will be described in which the AC vibration components of both the photosensitive drum having a rotation frequency of 0.5 Hz and the transfer belt drive roll having a rotation frequency of 3 Hz are detected.
First, in order to detect the AC vibration component of the photosensitive drum,
In order to eliminate the influence of the vibration component of the transfer belt drive roll, sampling is performed using a low-frequency color misregistration detection pattern set at the same frequency of 3 Hz as the rotation frequency of the drive roll, and the vibration frequency component, amplitude, etc. Detection is performed (steps S70, S71). Then, a correction value of the AC vibration component having the frequency of 3 Hz is set (step S72), and control based on the correction value is performed. next,
In order to detect an AC vibration component of the transfer belt drive roll, sampling is performed using a high-frequency detection pattern set to a high frequency of 20 Hz (step S73).
However, at this time, since the AC vibration component of the photosensitive drum has already been corrected, the A of the transfer belt drive roll can be easily adjusted.
C vibration component can be detected (step S7)
4).

Embodiment 7 This embodiment is different from the embodiment 4 described above in that each color AC register is detected and detected.
This shows another example in which a plurality of types of AC vibration components having different frequencies are detected in the calculation step (step S30). FIG. 44 shows the AC register detection / calculation process of this embodiment. That is, when there are low-frequency and high-frequency vibration components, one color misregistration detection pattern dedicated to a high-frequency AC color register with an interval P set to a predetermined high frequency is used as follows. Two AC
A vibration component is detected. Here, the high frequency of the color misregistration detection pattern may be set, for example, to be a common multiple of the AC vibration component to be detected.

First, a high-frequency color misregistration detection pattern is read (step S80). At this time, for example, FIG.
An AC vibration waveform component as shown in FIG. Then, only necessary data portions are extracted from the obtained sampling data at a predetermined frequency (step S81),
The amplitude and phase of the extracted low-frequency vibration component are detected (step S82). A low frequency vibration frequency component is calculated by interpolation from the obtained amplitude and phase data (step S83), and a correction value for the low frequency vibration frequency component is set (step S84). The interpolation at this time is
For example, a low-frequency vibration component cut out as shown in FIG. 45 (b) is approximated to a sine waveform, and the frequency component (waveform curve) Y is expressed as “Y = a · sin ω (t−α)” (a: amplitude,
α: phase). Next, a low-frequency vibration component is subtracted from the high-frequency sample data obtained previously (step S85). Thereby, for example, FIG.
An AC vibration component having a high frequency as shown in FIG. 5 (c) is obtained. Finally, the frequency component, amplitude, and phase of the high-frequency AC vibration component are detected (step S8).
6) A high frequency vibration frequency component is calculated by interpolation from the obtained amplitude and phase data (step S8).
7), a correction value of the high frequency vibration frequency component is set (step S88).

For example, in this embodiment, when detecting the AC vibration components of both the photosensitive drum having the rotation frequency of 0.5 Hz and the transfer belt drive roll having the rotation frequency of 3 Hz, the color misregistration detection pattern used is 20 Hz.
Can be used. Then, an AC vibration component of the photosensitive drum having a low frequency is first cut out at a frequency of 3 Hz.

In each of the above-described embodiments, an AC vibration component dependent on the photosensitive drum and the transfer belt drive roll has been mainly described as an example. However, the present invention is not limited to the AC vibration component depending on other factors. The same can be applied to the transfer belt. For example, the present invention can be applied to an AC vibration component in one rotation of the belt that depends on the belt thickness unevenness of the transfer belt.

[0154]

According to the present invention, there is provided the image forming apparatus according to the first aspect of the present invention, which is for detecting a periodic rotation fluctuation occurring in the image forming apparatus. Since it is configured to include the color misregistration detection pattern, even when the color misregistration detection pattern is formed under limited conditions, the periodic rotation fluctuation generated in the image forming apparatus is considered. Then, the color misregistration detection pattern may be formed, and the color misregistration detection pattern for detecting the periodic rotation fluctuation (vibration component) generated in the image forming apparatus can accurately detect the AC color registration misalignment. It is possible to control the drive system of the rotating body such as the photosensitive drum and the transfer belt actively, and obtain sufficient data as information to reduce the displacement of the AC color registration. That. Further, the image forming apparatus of the present invention
Has a plurality of patterns for detecting the color misregistration.
The period that occurs in the image forming apparatus
Even if there are multiple
Precise detection using the same color misregistration detection pattern
be able to.

On the other hand , an image forming apparatus according to a second aspect of the present invention has only one color misregistration detection pattern.
Since the single color misregistration detection pattern is configured to be sampled at a plurality of sampling frequencies, only one color misregistration detection pattern needs to be formed, and the color misregistration detection pattern can be easily formed. It can be carried out.

Further, in the image forming apparatus of the present invention, the color misregistration detection patterns are separately formed at least at two or more positions in the direction orthogonal to the moving direction of the endless carrier, and the respective detection patterns are separately formed. When sampling is performed in the image forming apparatus, periodic rotation fluctuations caused by different phases and amplitudes at both ends in the axial direction of the rotating body due to an eccentric component of the rotating body in the image forming apparatus,
Detection can be performed with high accuracy.

Further, the image forming apparatus according to the present invention is configured such that the color misregistration detection pattern is formed at a central portion in a direction orthogonal to the moving direction of the endless carrier, and the detection pattern is sampled . In such a case, a periodic rotation variation that occurs due to different phases and amplitudes at both ends in the axial direction of the rotating body due to an eccentric component of the rotating body in the image forming apparatus is generated at the center in the axial direction of the rotating body. It is possible to easily and efficiently detect the signals in a state where they are averaged to some extent. For this reason, two ends such as both ends in the axial direction of the rotating body.
There is no need to form a detection pattern at a location or more, sample the pattern, and average the obtained data.

In the image forming apparatus according to a third aspect of the present invention, the interval of the color misregistration detection pattern in the moving direction of the endless carrier is determined by the frequency of the periodic rotation fluctuation generated in the image forming apparatus. , The periodic rotation fluctuation occurring in the image forming apparatus can be accurately detected by a color misregistration detection pattern adapted to the fluctuation.

Further, the image forming apparatus according to claim 4 of the present invention seeks to detect the frequency at which the color misregistration detection pattern is sampled from a plurality of periodic rotation fluctuations generated in the image forming apparatus. Is configured so as to correspond to the frequency of the rotation fluctuation that occurs, even if there are a plurality of periodic rotation fluctuations that occur in the image forming apparatus, a specific periodic rotation fluctuation can be accurately detected. Can be detected.

In the image forming apparatus according to a fifth aspect of the present invention, the frequency at which the color misregistration detection pattern is sampled is set to a higher frequency among a plurality of periodic rotation fluctuations generated in the image forming apparatus. Since it is configured to be set corresponding to the rotation fluctuation, as can be seen from the sampling theorem, without detecting the rotation fluctuation with a high frequency,
Only rotation fluctuations with a low frequency can be detected.

Further, in the image forming apparatus according to the present invention, the color misregistration detection pattern is repeatedly formed at predetermined intervals along the moving direction of the endless carrier, and the color misregistration detecting pattern is moved in the moving direction of the endless carrier. A pattern formed along the direction perpendicular to the direction of movement of the endless carrier, and a pattern formed along the direction perpendicular to the direction of movement of the endless carrier. a configuration divided and to sample then, by sampling by separating the direction of the pattern of movement direction and perpendicular to the endless carrier, the pattern along the moving direction of the endless carrier spacing Even if is small, sufficient data processing time can be secured.

[0162] The image forming apparatus of the present invention, the color shift detection pattern, when configured to sample is divided for each color can be set narrow intervals of the color patterns, Even when the frequency of the periodic rotation fluctuation generated in the image forming apparatus is high, it can be detected accurately.

Further, in the image forming apparatus according to the sixth aspect of the present invention, different types of color misregistration detection patterns are separately formed at least at two or more positions in a direction orthogonal to the moving direction of the endless carrier. Since a predetermined control operation is performed using data obtained by separately sampling each detection pattern, a plurality of periodic rotation fluctuations occurring in the image forming apparatus can be accurately and efficiently detected. it can be. Also, since the sampling data obtained at the same time has the same phase, it is very effective for subsequent data processing and use .

In the image forming apparatus of the present invention, the same type of color misregistration detection pattern is separately formed in at least two places in the direction perpendicular to the direction of movement of the endless carrier, and the respective detection patterns are separately formed. taken together after sampling when using the averaged data configured to perform predetermined control operation, such as an eccentric component of the rotating body in the image forming apparatus of the rotary body axis direction due It is possible to reliably and accurately detect periodic rotation fluctuations that occur with different phases and amplitudes at both ends, and perform an optimal control operation that also takes such eccentric components and the like into account.

In the image forming apparatus according to a seventh aspect of the present invention, a plurality of color misregistration detection patterns having different frequency characteristics are formed and sampled by setting a pattern interval, and sampling is performed using a high frequency detection pattern. By subtracting the vibration waveform component obtained by sampling with a low-frequency detection pattern from the vibration waveform component obtained by
Since the vibration component related to the high-frequency rotation fluctuation is configured to be extracted, the rotation fluctuation having a different frequency among the periodic rotation fluctuations generated in the image forming apparatus can be efficiently detected. In particular, when a plurality of color misregistration detection patterns having different frequency characteristics are sampled simultaneously, since the phase is the same, the subtraction of the vibration waveform component can be easily performed as it is, and more efficiency can be achieved. Good detection becomes possible.

In the image forming apparatus according to the eighth aspect of the present invention, when performing sampling and control operations using a plurality of color misregistration detection patterns having different frequency characteristics by setting the pattern interval, a low frequency is used. At least one
It is configured to perform the sampling and control operation using one detection pattern and then perform the sampling and control operation using at least one detection pattern having the next lower frequency. The detection of the periodic rotation fluctuation of the high frequency to be performed is performed in a state where the rotation fluctuation of the lower frequency has already been eliminated, so that it can be easily and accurately performed.

The image forming apparatus according to the ninth aspect of the present invention forms a pattern for detecting color misregistration having a high frequency, performs sampling, and extracts only a vibration component having a low frequency from the sampling data to thereby reduce the frequency. Since it is configured to detect a vibration component related to low-speed rotation fluctuation, and to detect a vibration component related to high-frequency rotation fluctuation by subtracting the vibration component related to low-frequency rotation fluctuation from the sampling data, , A plurality of types of periodic rotation fluctuations can be detected efficiently.

[0168] Furthermore, the image forming apparatus according to claim 1 0 of the present invention, at least one of the coarse adjustment and fine adjustment of DC color registration correction cycle of sampling of the color shift detection pattern, immediately after the power-on of the device When the AC color registration deviation is detected, at least the coarse adjustment of the DC color registration correction cycle has been completed, and the periodic rotation generated in the image forming apparatus has been completed. It is possible to accurately form a color misregistration detection pattern for detecting a change, and it is possible to reliably prevent the color misregistration detection pattern from overlapping or the like. Furthermore, if the sampling and correction cycle of the AC color misregistration detection pattern is performed between the coarse adjustment and the fine adjustment of the DC color registration correction cycle immediately after the power is turned on, the fine adjustment of the subsequent DC color registration correction cycle can be performed with high accuracy. Can do well.

[Brief description of the drawings]

FIG. 1A is a conceptual diagram showing an image forming apparatus according to the present invention, and FIG. 1B is a plan view showing an AC color misregistration detection pattern.

FIG. 2 is a configuration diagram showing one embodiment of a digital color copying apparatus according to the present invention.

FIG. 3 is a configuration diagram showing one embodiment of a digital color copying apparatus according to the present invention.

FIG. 4 is a configuration diagram illustrating a driving device of a photosensitive drum.

FIG. 5 is a graph showing the rotation fluctuation of the photosensitive drum of each color.

FIG. 6 is a perspective view showing a main part of an embodiment of a digital color copying apparatus according to the present invention.

FIG. 7 is a cross-sectional configuration diagram showing a sensor.

FIG. 8 is a perspective view showing the same sensor.

FIG. 9 is a graph showing the relationship between transmittance and wavelength.

FIG. 10 is a graph showing the relationship between the relative output of the sensor and the wavelength of incident light.

FIG. 11 is a waveform diagram showing an output of a sensor.

FIG. 12 is a plan view showing a pattern for DC registration displacement measurement.

FIG. 13 is a block diagram showing a control circuit of the digital color copying machine according to the present invention.

FIGS. 14A and 14B are plan views showing patterns for measuring AC registration deviation.

FIGS. 15A and 15B are tables showing the relationship between the frequency of rotation fluctuation and the sampling frequency, respectively.

16 (a) to 16 (d) are graphs each showing an example of sampling of rotation fluctuation.

FIG. 17 is a flowchart showing a color misregistration correction operation.

FIG. 18 is a flowchart showing a color misregistration correction operation.

FIG. 19 is a flowchart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 20 is a flow chart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 21 is a flowchart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 22 is a flowchart showing the operation of the color shift detection pattern sampling apparatus according to this embodiment.

FIG. 23 is a flowchart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 24 is a flowchart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 25 is a flowchart showing the operation of the color misregistration detection pattern sampling apparatus according to this embodiment.

FIG. 26 is a graph showing a method for detecting the rotation phase of the photosensitive drum.

FIG. 27 is a graph showing a method for detecting the rotation phase of the photosensitive drum.

FIGS. 28A and 28B are graphs showing a method of detecting the rotation phase of the photosensitive drum, respectively.

FIG. 29 is an explanatory diagram showing a typical pattern of the eccentric component of the rotating body according to this embodiment.

FIG. 30 shows an example of a control result when pattern sampling is performed at one point in the main scanning direction of the rotating body. FIG. 30 (a) is a waveform diagram showing a state before correction.
(B) is a waveform diagram showing a state after the correction.

FIG. 31 shows another example of a control result when pattern sampling is performed at one position in the main scanning direction of the rotating body. FIG. 31 (a) is a waveform diagram showing a state before correction.
(B) is a waveform diagram showing a state after the correction.

FIG. 32 is a waveform diagram showing a control result in a case where the vibration component shown in FIG. 30A is sampled according to this embodiment.

FIG. 33 is a waveform diagram showing a control result when sampling according to this embodiment is performed on the vibration component shown in FIG. 31 (a).

FIG. 34 is a plan view showing an AC registration deviation measurement pattern according to another embodiment (Example 2) of the present invention.

FIG. 35 is a plan view showing an AC registration deviation measurement pattern according to still another embodiment (Embodiment 3) of the present invention.

FIG. 36 is a plan view showing an AC registration deviation measurement pattern according to still another embodiment (Embodiment 3) of the present invention.

FIG. 37 is a flowchart illustrating another example (Example 4) of the color misregistration correction operation.

FIG. 38 is a flowchart showing detection and calculation of an AC color register when the same type of detection pattern is used.

FIG. 39 is a flowchart showing the detection and calculation of an AC color register when different types of detection patterns are used simultaneously.

FIG. 40 is a flowchart showing detection and calculation of an AC color register when different types of detection patterns are used (Embodiment 5).

FIG. 41 is an AC oscillation waveform diagram for explaining the detection / calculation of FIG. 40.

FIG. 42 is a flowchart showing detection and calculation of an AC color register when different types of detection patterns are used in another process (Embodiment 6).

FIG. 43 is an AC vibration waveform diagram for explaining detection / calculation in FIG. 42.

FIG. 44 is a flowchart showing detection / calculation of an AC color register when one detection pattern is used in another process (Embodiment 7).

FIG. 45 is an AC oscillation waveform diagram for explaining detection / calculation in FIG. 44.

FIG. 46 is a configuration diagram showing a digital color copying apparatus to which a conventional sampling apparatus for a color misregistration detection pattern is applied.

FIG. 47 is an explanatory diagram showing a color misregistration detection pattern.

[Explanation of symbols]

01 endless carrier, 02 transfer material, 03K, 03Y,
03M, 03C Image forming means, 04 color shift correction means, 05 color shift detection pattern.

Continuation of front page (56) References JP-A-6-253151 (JP, A) JP-A-6-79917 (JP, A) JP-A-6-137812 (JP, A) JP-A-2-297574 (JP) JP-A-6-35290 (JP, A) JP-A-6-51607 (JP, A) JP-A-7-199576 (JP, A) JP-A-7-36244 (JP, A) 7-271125 (JP, A) JP-A-6-261177 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/01 G03G 15/01-15/01 117

Claims (10)

(57) [Claims] An image is formed by forming a plurality of images of different colors directly on a transfer material carried on a rotatably driven endless carrier or directly on the endless carrier. An image forming apparatus configured to form a pattern for detecting color misregistration on an endless carrier to be sampled, sample these color misregistration detection patterns, and perform a predetermined control operation. A color misregistration detection pattern for detecting a periodic rotation fluctuation generated in the device is provided , and the color misregistration is detected.
In the direction of movement of the endless carrier
With different pattern intervals
An image forming apparatus having the following patterns . 2. An endless carrier supported on a rotatably driven endless carrier.
The transfer material having different colors is directly applied to the transfer material or the endless carrier.
Forming an image by forming a number of images
To detect a color shift on the rotatably driven endless carrier.
Of these color misregistration detection patterns.
It is configured to perform a predetermined control operation by sampling.
The periodic rotation fluctuation occurring in the image forming apparatus is detected.
Color misregistration detection pattern for
And has only one pattern for detection
The detection pattern can be sampled at multiple sampling frequencies.
An image forming apparatus characterized by performing pulling . 3. An endless carrier that is driven to rotate.
The transfer material having different colors is directly applied to the transfer material or the endless carrier.
Forming an image by forming a number of images
To detect a color shift on the rotatably driven endless carrier.
Of these color misregistration detection patterns.
It is configured to perform a predetermined control operation by sampling.
The periodic rotation fluctuation occurring in the image forming apparatus is detected.
Color misregistration detection pattern for
Between the endless carrier in the moving direction of the endless detection pattern
Gap between the periodic rotation fluctuations occurring in the image forming apparatus.
An image forming apparatus , wherein the image forming apparatus is set according to a frequency . 4. An endless carrier supported on a rotatably driven endless carrier.
The transfer material having different colors is directly applied to the transfer material or the endless carrier.
Forming an image by forming a number of images
To detect a color shift on the rotatably driven endless carrier.
Of these color misregistration detection patterns.
It is configured to perform a predetermined control operation by sampling.
The periodic rotation fluctuation occurring in the image forming apparatus is detected.
Color misregistration detection pattern for
The frequency at which the detection pattern is sampled is
Of a plurality of periodic rotation fluctuations occurring in the image forming apparatus,
Set according to the frequency of rotation fluctuation to be detected.
An image forming apparatus characterized in that: 5. An endless carrier supported on a rotatably driven endless carrier.
The transfer material having different colors is directly applied to the transfer material or the endless carrier.
Forming an image by forming a number of images
To detect a color shift on the rotatably driven endless carrier.
Of these color misregistration detection patterns.
It is configured to perform a predetermined control operation by sampling.
The periodic rotation fluctuation occurring in the image forming apparatus is detected.
Color misregistration detection pattern for
The frequency at which the detection pattern is sampled is
Of a plurality of periodic rotation fluctuations occurring in the image forming apparatus,
It is set to correspond to high frequency rotation fluctuation.
An image forming apparatus. 6. An endless pattern for detecting different types of color misregistration.
At least two places in the direction perpendicular to the direction of movement of the carrier
Separately, and each detection pattern is separately supported.
Perform predetermined control operations using the sampled data
The image forming apparatus according to claim 1 or 2, characterized in that. 7. The frequency characteristic is set by setting a pattern interval.
A sample is formed by forming a plurality of different color misregistration detection patterns.
Sampling with a high-frequency detection pattern.
Low-frequency detection pattern from the vibration waveform component
By subtracting the vibration waveform component obtained by sampling
To extract vibration components related to high-frequency rotation fluctuation
The image forming apparatus according to claim 1 or 2, characterized in that. 8. The frequency characteristic is set by setting a pattern interval.
Using multiple different color misregistration detection patterns,
When performing pulling and control operations, use
Sampling using one detection pattern
And after performing the control operation, the next lowest frequency
Also uses one detection pattern for sampling and
Claim 1, characterized in that to perform the fine control operation
Or the image forming apparatus according to 2. 9. A color misregistration detection pattern having a high frequency is formed.
And sample it.
By extracting only vibration components with low wave numbers,
Vibration components related to low rotation fluctuations are detected.
The vibrations related to low-frequency rotation fluctuations are
By subtracting the dynamic component, it is possible to
The image forming apparatus according to claim 2, wherein a vibration component that changes is detected . 10. A sample of the color misregistration detection pattern.
The DC color registration correction cycle after turning on the power to the device.
After at least one of coarse adjustment and fine adjustment of
The image forming apparatus according to claim 1, wherein the image forming apparatus is implemented .