JP2003162123A - Image forming device - Google Patents

Abstract

(57) [Problem] To provide an image forming apparatus capable of accurately performing more accurate registration correction and printing high quality image. SOLUTION: After image density correction is performed by an image density correction unit, registration deviation correction based on a result of a registration deviation detection unit is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus adopting an electrophotographic system or an electrostatic recording system, and in particular,
A visible image formed on a plurality of image carriers is multi-transferred to a transfer material carried on an endless belt-shaped transfer material conveying body or to an endless belt-shaped intermediate transfer body to form a multicolor image. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a multicolor image forming apparatus having a function of automatically correcting an image shift when forming multiple images.

[0002]

2. Description of the Related Art Conventionally, a plurality of image forming portions are provided, and in each image forming portion, a laser beam light or LE is formed on a drum-shaped electrophotographic photosensitive member as an image bearing member, that is, a photosensitive drum.
By irradiating light from a light emitting element such as D, an electrostatic latent image is formed on the photosensitive drum by an electrophotographic process, and the electrostatic latent image is developed by a developing device to form a visible image (toner image).
The toner images formed on the photoconductor drums in the respective image forming units are transferred to the transfer member by a transfer unit, and the toner images are multiple-transferred onto a transfer material conveyed by a belt-shaped transfer material conveying member (transfer conveying belt). There has been proposed a multicolor image forming apparatus capable of forming a color image by a method such as multiple transfer of each image on a sheet-shaped intermediate transfer body (intermediate transfer belt), and then batch transfer to a transfer material.

In this type of image forming apparatus, each photosensitive drum is caused by a mechanical mounting error between the photosensitive drums, an optical path length error of each laser beam, an optical path change, or a warp due to the ambient temperature of the LED. The registration of each color image formed above will not match on the transfer material that is finally multi-transferred.

Therefore, conventionally, a registration sensor including a light emitting element and a light receiving element forms a registration correction pattern image formed on an endless belt such as an intermediate transfer belt (or a transfer conveyance belt) from each photosensitive drum. Etc., and detects misregistration on the photoconductor drum corresponding to each color, electrically corrects the image signal to be recorded, and in addition, or as an alternative, is provided in the laser beam optical path. The folding mirror is driven to correct the optical path length change or the optical path change.

[0005]

However, in the above-mentioned image forming apparatus, the detection accuracy of the registration sensor is affected in accordance with the density fluctuation of the registration correction pattern image, and the registration correction accuracy is extended accordingly. Could cause problems.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an image forming apparatus capable of accurately performing registration correction with higher accuracy and printing a high quality image.

[0007]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention is
A plurality of image forming units arranged side by side is provided, and each of the image forming units develops a first image carrier and an electrostatic latent image formed on the first image carrier to form a visible image. A developing device, and a visible image formed on each of the image forming units on the first image carrier is carried on the second image carrier or on the second image carrier. An image forming apparatus which is transferred to be superposed on the transfer material, wherein registration error detecting means for detecting a registration error measuring pattern image formed on the second image carrier by the plurality of image forming units; Registration deviation correction means for correcting the registration of each image forming portion based on the result of the registration deviation detection means, and an image density measuring pattern formed on the second image carrier by the plurality of image forming portions. An image density detecting means for detecting an image and the image density detecting means. Image density correction means for correcting the density of the image formed by each of the image forming units based on the result of the detection means, and after performing the image density correction by the image density correction means, the registration deviation detection means The image forming apparatus is characterized by performing registration misregistration correction based on the result.

According to one embodiment of the present invention, the image density correction timing by the image density correction means is after the power is turned on, and then the registration deviation correction is performed.

According to another embodiment of the present invention, the image density correction timing by the image density correction means is after the power is turned on, and then the registration deviation correction is performed at a predetermined number of print intervals or a predetermined time interval. To do.

According to another embodiment of the present invention, the image density correction timing by the image density correction means is after power is turned on, and thereafter, from the start to the return to the power saving mode for reducing the device power in the standby mode. It is determined whether or not the registration shift correction is performed according to the time.

According to another embodiment of the present invention, the image density correction timing by the image density correction means is after power is turned on, and thereafter, according to the setting contents of the power saving mode for reducing the device power in the standby mode. It is determined whether or not the registration shift correction is performed.

According to another embodiment of the present invention, the registration shift correction is not performed when the color setting of the image forming apparatus is set to the black monochromatic mode or when it is determined that the black monochromatic image is output.

According to another embodiment of the present invention, the image density correction timing by the image density correction means is after the power is turned on, and thereafter, according to the in-machine temperature detected by the temperature detection means for detecting the in-apparatus temperature. It is determined whether or not the registration shift correction is performed.

According to another embodiment of the present invention, the image density correction timing by the image density correction means is after the power is turned on, and thereafter, the human body detection result detected by detecting the presence or absence of the human body in the vicinity of the apparatus is used. Accordingly, it is determined whether or not the registration shift correction is performed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic sectional view showing the overall construction of an electrophotographic color copying machine according to an embodiment of the image forming apparatus of the present invention. The electrophotographic color copying machine of the present embodiment is a color image output device in which a plurality of image forming units are arranged in parallel and which adopts an intermediate transfer system, which is considered to be particularly applicable to the present invention.

In this embodiment, the electrophotographic color copying machine is
It has an image reading unit 1R and an image output unit 1P. The image reading unit 1R optically reads a document image, converts it into an electric signal, and sends it to the image output unit 1P. Image output unit 1P
Is a plurality of image forming units 1 arranged in parallel in this embodiment.
0 (10a, 10b, 10c, 10d), the paper feeding unit 20, the intermediate transfer unit 30, and the fixing unit 40.
And a control unit (not shown).

Further, each unit will be described in detail.

Each image forming section 10 (10a, 10b, 10)
c, 10d) have the same configuration, and each image forming unit 10 (1
0a, 10b, 10c, 10d), the drum-shaped electrophotographic photosensitive member as the first image carrier, that is, the photosensitive drum 11 (11a, 11b, 11c, 11d) is rotatably supported by the arrow. Driven to rotate. The primary charger 12 (12a, 12b, 12c, 12d), the optical system 13 (13a, 13b, 13c, 13d), the folding mirror 16 (16a, 16a, 16b, 16c, 16d), the developing device 14 (14a, 14b, 14c, 14d), and the cleaning device 15 (15a, 15b, 15c, 15).
d) is arranged.

In the primary chargers 12a to 12d, the surfaces of the photoconductor drums 11a to 11d are given a uniform amount of charge. Next, the optical systems 13a to 13d modulate the recording image signal from the recording image signal output section 1R,
For example, a light beam such as a laser beam is folded back to the mirror 16
By exposing the photosensitive drums 11a to 11d through a to 16d, an electrostatic latent image is formed thereon.

Further, the electrostatic latent images are visualized by the developing devices 14a to 14d which respectively contain four color developers (hereinafter referred to as "toners") of yellow, cyan, magenta and black. The visualized visible image is transferred to the belt-shaped intermediate transfer member, that is, the intermediate transfer belt 31 as the second image carrier constituting the intermediate transfer unit 30 in the image transfer areas Ta, Tb, Tc, and Td. To do.
The intermediate transfer unit 30 will be described in detail later.

On the downstream side of the image transfer areas Ta, Tb, Tc, Td, the cleaning devices 15a, 15b, 15c,
The photosensitive drum 1 is not transferred to the intermediate transfer member by 15d.
The toner remaining on the surfaces 1a to 11d is scraped off to clean the drum surface. By the process described above, image formation with each toner is sequentially performed.

The paper feeding unit 20 includes cassettes 21a and 21b for storing the transfer material P and a manual feed tray 27.
And cassettes 21a, 21b or manual feed tray 27
Pickup rollers 22a, 22b, 26 for feeding the transfer material P one by one, and each pickup roller 2
2a, 22b, and 26, a pair of paper feed rollers 23 for conveying the transfer material P to the registration rollers, a paper feed guide 24, and the transfer material P at the image forming timing of each image forming unit. It has registration rollers 25a and 25b for sending it to the secondary transfer area Te.

The intermediate transfer unit 30 will be described in detail.

The intermediate transfer belt 31 is the intermediate transfer belt 3
A driving roller 32 that transmits the driving force to the first transfer roller 1, and a driven roller 33 that follows the rotation of the intermediate transfer belt 31 as a tension roller that applies an appropriate tension to the intermediate transfer belt 31 by the urging of a spring (not shown). , A secondary transfer counter roller 3 that faces the secondary transfer area Te with the belt in between.
It is wound tightly between 4 and. Of these, the primary transfer plane A is formed between the drive roller 32 and the driven roller 33. As the intermediate transfer belt 31, for example, PET
(Polyethylene terephthalate), PVdF (polyvinylidene fluoride) or the like is used. The drive roller 32 is
The surface of the metal roller is coated with rubber (urethane or chloroprene) having a thickness of several mm to prevent slippage with the belt. The drive roller 32 is a pulse motor (not shown)
It is driven to rotate by.

In the primary transfer areas Ta to Td where the photosensitive drums 11a to 11d and the intermediate transfer belt 31 face each other, the primary transfer charger 35 (35a) is provided on the back of the intermediate transfer belt 31.
~ 35d) are arranged. On the other hand, a secondary transfer roller 36 is arranged so as to face the secondary transfer counter roller 34, and a secondary transfer area Te is formed by a nip with the intermediate transfer belt 31. The secondary transfer roller 36 is the intermediate transfer belt 31.
It is pressurized with moderate pressure.

A cleaning device 50 for cleaning the image forming surface of the intermediate transfer belt 31 is arranged downstream of the secondary transfer area Te of the intermediate transfer belt 31. The cleaning device 50 includes a cleaning blade 51 for removing toner on the intermediate transfer belt 31,
A waste toner box 52 for storing waste toner is provided.

The fixing unit 40 has a fixing roller 41a having a heat source such as a halogen heater therein and a pressure roller 41b (which may be provided with a heat source). Further, the roller pairs 41a, 4
The guide 43 for guiding the transfer material P to the nip portion of 1b, the fixing heat insulating covers 46, 47 for confining the heat of the fixing unit inside, and the transfer material P discharged from the roller pair 41a, 41b are further added. An internal paper discharge roller 44 for guiding the paper to the outside of the apparatus, an external paper discharge roller 45, a paper discharge tray 48 on which the transfer material P is stacked, and the like are provided.

Although not shown, the control unit
It has a control board and a motor drive board for controlling the operation of the mechanism in each unit.

Next, the operation of the electrophotographic color copying machine having the above structure will be described.

The control unit has a CPU for controlling the operation of the mechanism in each unit, and when an image forming operation start signal is issued from the CPU, the paper feed selected according to the selected paper size or the like. Feeding operation starts from the stage.

For example, when the paper is fed from the upper paper feed stage, the transfer material P is first fed from the cassette 21a one by one by the pickup roller 22a in FIG. Then, the transfer material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and conveyed to the registration rollers 25a and 25b. At that time, the registration rollers 25a and 25b are stopped, and the leading end of the transfer material P hits the nip portion. After that, the registration roller 25 is synchronized with the timing when the image forming unit starts image formation.
a and 25b start rotating. This rotation timing is the transfer material P
The timing is set so that the toner image primarily transferred onto the intermediate transfer belt 31 from the image forming unit coincides with the secondary transfer area Te.

On the other hand, in the image forming section, when the image forming operation start signal is issued, the toner image formed on the most upstream photosensitive drum 11d in the rotation direction of the intermediate transfer belt 31 by the above-mentioned process is The primary transfer area T is charged by the primary transfer charger 35d to which a high voltage is applied.
At d, the image is primarily transferred to the intermediate transfer belt 31. The primary-transferred toner image is conveyed to the next primary transfer area Tc. There, the image formation is performed with a delay between the image forming units by the time when the toner image is conveyed, the resist is aligned on the previous image, and the next toner image is transferred. The same steps are repeated below, and eventually the four color toner images are primarily transferred onto the intermediate transfer belt 31.

After that, when the transfer material P enters the secondary transfer area Te and comes into contact with the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in accordance with the passage timing of the transfer material P. As a result, the four color toner images formed on the intermediate transfer belt 31 by the above-described process are transferred to the surface of the transfer material P. After that, the transfer material P is accurately guided by the conveyance guide 43 to the fixing roller nip portion. Then, the toner image is fixed on the surface of the transfer material P by the heat of the roller pairs 41a and 41b and the pressure of the nip.
After that, the transfer material P is conveyed by the inner and outer paper discharge rollers 44 and 45, and is discharged to the outside of the machine.

In the image forming apparatus having the above structure,
Image density detection means 100 is provided.

That is, when the environment changes or each part of the apparatus changes due to long-term use, the density or chromaticity of the obtained image changes. Particularly in the case of an electrophotographic color image forming apparatus, even if a slight change in density is caused, the color balance may be disturbed. Therefore, it is necessary to always maintain constant density and gradation.

Therefore, the toner of each color has several kinds of exposure amount corresponding to absolute humidity, process conditions such as developing bias, and gradation correction means such as a look-up table (LUT), and is measured by a temperature / humidity sensor. The process condition and gradation correction value at that time are selected based on the absolute humidity.

Further, a pattern image for density detection, that is, a toner patch is formed by a toner of each color, that is, a toner patch, so that a constant density, gradation, and tint can be obtained even if a change occurs in each part of the apparatus during use. The toner patch is formed on the image sensor 31 and is detected by the image density detecting means 100 such as an optical sensor. As a result, a stable image can be obtained.

Next, a characteristic part of this embodiment will be described with reference to FIGS.

FIG. 2 shows a pattern image detecting means including an LED and a photodiode for detecting a registration correction pattern image of an image forming apparatus showing a characteristic portion of the first embodiment of the present invention, that is, a register. Deviation detection means 60
It is a schematic diagram of the vicinity.

The intermediate transfer belt 31 is made of rubber as a raw material.
・ You can use Young's body in the circumferential direction by using elastic body such as elastomer.
Rate is 1 × 10⁷Pa or higher. Of the intermediate transfer belt 31
The thickness ensures the thickness accuracy and strength, and the flexible rotary drive.
From the viewpoint of realizing
Yes. Further, the intermediate transfer belt 31 is made of metal powder (carbon
The desired resistance value (volume resistance) can be obtained by adding a conductive agent such as
1 × 10 as the resistance value ¹¹Ωcm or less is desirable)
Has been done. Also, it rotates in the direction of arrow B to move it within area C.
And the drive is transmitted by wrapping around the drive roller 32.
ing.

On the other hand, the registration deviation detecting means 60 is located between the drive roller 32 and the most downstream photosensitive drum 11a in the belt advancing direction among the plurality of photosensitive drums, and the position on the intermediate transfer belt 31. At Sa, the registration correction pattern image formed on the intermediate transfer belt 31 is read. Further, as shown in FIG. 3 (a top view of the main part of FIG. 2), they are arranged at both ends of the intermediate transfer belt 31.

In the image forming apparatus, before performing the image forming operation, the registration correction pattern image 70 is formed on the intermediate transfer belt 31 at a predetermined timing, read by the registration deviation detecting means 60, and the exposure corresponding to each color is performed. The registration deviation on the body drum is detected, the image signal to be recorded is electrically corrected, and / or the folding mirror 16a provided in the optical path of the laser beam.
Is driven to correct the optical path length change or the optical path change.

At this time, according to the present embodiment, the registration correction pattern image 70 formed on the intermediate transfer belt 31 by the plurality of photosensitive drums including the photosensitive drum 11a is rotated by the rotation of the intermediate transfer belt 31. Area C
The registration deviation detecting means 60 before the contact start point C1 between the intermediate transfer belt 31 and the drive roller 32 before the intermediate transfer belt 31 scatters due to the expansion and contraction of the surface of the intermediate transfer belt 31 and deteriorates the image quality. Since the registration correction mark image is read at the position Sa, erroneous detection due to image deterioration of the registration correction pattern image 70 can be prevented, and accurate registration correction can be realized.

FIG. 4 is a flow chart showing an embodiment of the registration correction sequence executed according to the present invention. The process after the power is turned on will be described.

First, the power is turned on (S6-1), and then the process stands by until an image can be formed on the intermediate transfer belt 31 (S6-2).

When image formation becomes possible, first, a patch image 70 for image density correction is formed on the belt 31 (S6-3). Image density correction is performed using this patch image (S6-4). Of course, the registration misregistration correction sequence is not performed when the color setting of the color printer is set to the black monochromatic mode or when it is determined that the black monochromatic image is output.

In this embodiment, since the color printer is set to full color, image density correction is performed for all four YMCK colors. When the image density corrections of the four colors are completed, the registration shift correction patch inspection is started (S6-5).

After that, the number of prints is set by the user (S6-6), and the number of prints is stacked (S6).
-7).

A print command is issued (S6-8), and (S6
-9), the number of sheets actually printed is counted, and the count value N is stacked (S6-10). The predetermined number X of sheets determined in advance is compared with the counted number of sheets previously stacked (S6-11), and if N <X, it is judged whether or not the number of prints set by the user is completed (S6).
-12), if not finished, return to S16-10, count the number of prints, compare N and X,
If N> = X, the registration shift is corrected (S6-1).
3) A series of operations is repeated until printing is completed.

Embodiment 2 FIG. 6 is a flowchart showing an embodiment of the registration correction sequence according to the present invention.

First, as in the first embodiment, the power is turned on (S7-1), and the process stands by until an image can be formed on the intermediate transfer belt 31 (S7-2). When image formation becomes possible, first, the patch image 70 for image density correction
Is formed on the belt 31 (S7-3). Image density correction is performed using this patch image 70 (S7-4).

In this embodiment, since the printer is a color printer, the image density of all four colors of YMCK is corrected and the standby state is set.

When a predetermined power saving condition, for example, a standby for a predetermined time is continued, the power saving mode is shifted to the power saving mode (7-5) by an instruction from the user, for example, and the power saving mode waiting time t
s is measured (S7-6), it is determined whether or not the power saving mode has been canceled (S7-7), and until the power saving mode is canceled, the power saving mode standby time ts is measured and S in S7-6 above.
Repeat judgment 7-7. When it is determined in S7-7 that the power saving mode has been canceled, it is determined in S7-8 whether the time is less than a predetermined time T, and ts> T.
If, then the registration correction described above is performed. If ts <T, the above-mentioned registration correction is not performed and the printing operation is started (S6-).
10).

Embodiment 3 Next, another embodiment of the image forming apparatus according to the present invention will be described.

There are cases where it is necessary to perform the above-mentioned registration correction due to expansion and contraction or distortion of side plates of the apparatus due to fluctuations in the temperature inside the image forming apparatus. However, when waiting in a standby state after a print job and then performing printing, it is not always necessary to perform registration correction, and it is necessary to determine whether to perform the registration correction according to the temperature inside the machine. Thus, it is possible to shorten the recovery time from energy saving, standby or power saving mode.

The image forming apparatus of this embodiment has the same structure as the image forming apparatus described in the first embodiment shown in FIG. 1, except that a temperature sensor (not shown) for detecting the temperature inside the machine is installed. The only difference is that it is done.

Registration correction using this temperature sensor will be described with reference to the flow chart of FIG.

First, the power is turned on (S8-1,), and the process stands by until an image can be formed on the intermediate transfer belt 31 (S8-2). When image formation becomes possible, first, the patch image 70 for image density correction is transferred to the intermediate transfer belt 31.
Form on top (S8-3). The image density is adjusted by the patch image 70 (S8-4).

In this embodiment, since the printer is a color printer, the image density of all four colors of YMCK is corrected and the standby state is set.

After that, when a predetermined power saving condition, for example, a standby for a predetermined time is continued, the power saving mode is entered by an instruction from the user (S8-5), and it is determined whether or not the power saving mode is released. (S8-6) When it is determined that the power saving mode has been canceled, the temperature difference Δ between the in-machine temperature t1 stored when the registration correction was previously performed and the current in-machine temperature t2 in S8-3. T is calculated (S8-7). It is determined whether or not it is less than a predetermined temperature change T inside the machine, and if ΔT> Ta, the above-described registration correction is performed. Also, ΔT <T
If it is a, the printing operation is started without performing the above-mentioned registration correction (S8-8).

Embodiment 4 Next, another embodiment of the image forming apparatus according to the present invention will be described.

The image forming apparatus of this embodiment is the same as the first embodiment.
The configuration is similar to that of the image forming apparatus described in
Furthermore, the only difference is that a sensor (not shown) for detecting the presence or absence of a human body near the device is installed.

Also in this embodiment, after the print job,
When waiting in the standby state and printing after that, by detecting the presence of the operator and determining whether or not to perform the registration correction, it is possible to shorten the time for returning from energy saving, standby or power saving mode. is there.

Registration correction using this human body detection sensor can also be performed, for example, in the same manner as in the third embodiment, and similar operational effects can be obtained.

That is, as in the third embodiment, the image density is corrected and the standby state is set. After that, when a predetermined power saving condition, for example, when waiting for a predetermined time is continued,
When the human body detection sensor detects the presence of an operator,
Cancel the power saving mode and determine whether or not registration correction should be performed. The subsequent sequence is the third embodiment.
Is the same as.

Embodiment 5 FIG. 7 shows another embodiment of the image forming apparatus of the present invention. In the electrophotographic color copying machines described in Embodiments 1 to 4, the second image carrier 31 was used as the intermediate transfer belt, but in the electrophotographic color copying machines of this embodiment, the second image carrier 31 was used. Transfer material P
The transfer material conveying belt that carries and conveys the same, and is otherwise configured similarly to the electrophotographic color image forming apparatus of the first embodiment. Therefore, members having the same function and action are designated by the same reference numerals, and further description will be omitted.

In this embodiment as well, as will be understood by referring to FIG. 2 as in the case of the first embodiment, the pattern detection means 60 (61) for detecting the image image for detecting the image shift, A plurality of photosensitive drums 11 (11a, 1)
1b, 11c, 11d) is formed on the transfer material transport belt 31 at a position Sa on the transfer material transport belt 31, which is located further downstream than the most downstream photosensitive drum 11a in the belt traveling direction. The formed image shift detection pattern image is read. Also, the detection means 60 (61)
Are arranged at both ends of the intermediate transfer belt 31, as shown in FIG. 3 described in the first embodiment. This detection means 60
Correction is performed based on the image shift amount detected in (61). Further, an image density detecting means 100 for detecting the image density measuring pattern image is also arranged.

Also in this embodiment, as in the case of the first to fourth embodiments, the density correction and the registration deviation correction operation are performed,
The same effect can be obtained.

[0070]

As described above, the image forming apparatus of the present invention is configured to perform the registration deviation correction based on the result of the registration deviation detection means after the image density correction means performs the image density correction. The registration correction after the image density correction is properly performed when necessary, and the registration correction error due to the difference in image density can be further reduced to obtain a high quality image.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an electrophotographic color copying machine which is an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic configuration diagram of a region in which a detection unit that detects a registration correction pattern is provided.

FIG. 3 is a top view of the region where the detection means shown in FIG. 2 is provided as seen from above.

FIG. 4 is a flowchart showing an embodiment of a registration deviation correction operation.

FIG. 5 is a flowchart showing another embodiment of the registration deviation correction operation.

FIG. 6 is a flowchart showing another embodiment of the registration shift correction operation.

FIG. 7 is a schematic cross-sectional view of an electrophotographic color copying machine which is another embodiment of the image forming apparatus of the invention.

[Explanation of symbols]

10 (10a, 10b, 10c, 10d) Image forming unit 11 (11a, 11b, 11c, 11d) First image carrier (electrophotographic photoreceptor) 14 (14a, 14b, 14c, 14d) Developing device 31 Second Image carrier (intermediate transfer member, transfer material conveying member) 60, 61 registration deviation correction pattern detection means 70 registration deviation measurement pattern image 100 image density detection means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/00 398 G03G 21/00 398 21/14 372 F term (reference) 2H027 DA13 DA29 DA32 DA35 DA39 DA44 DA45 DE02 DE04 DE07 DE09 EA02 EA05 EB04 EC04 EC06 EC07 EC18 EC20 ED04 ED06 ED09 EE01 EE02 EE07 EF02 EF07 EF08 EF09 FA28 FA35 ZA07 2H030 AA01 AB02 AD08 AD17 AD18 BB02 BB16 BB34 BB42 BB46

Claims (8)

[Claims] 1. A plurality of image forming units arranged side by side, each image forming unit developing a first image carrier and an electrostatic latent image formed on the first image carrier. A developing device for forming a visible image, and a visible image on the first image carrier formed in each of the image forming units is formed on the second image carrier,
Alternatively, in an image forming apparatus that is transferred by being superposed on a transfer material carried on the second image carrier, for measuring a registration deviation formed on the second image carrier by the plurality of image forming units. A registration deviation detection unit that detects a pattern image, a registration deviation correction unit that corrects the registration of each image forming unit based on the result of the registration deviation detection unit, and the second image by the plurality of image forming units. Image density detecting means for detecting a pattern image for image density measurement formed on a carrier, and image density correcting means for correcting the density of the image formed by each image forming section based on the result of the image density detecting means. And an image forming apparatus, wherein after performing the image density correction by the image density correcting means, the registration deviation correction is performed based on the result of the registration deviation detecting means. Place 2. The image forming apparatus according to claim 1, wherein the image density correction timing by the image density correction means is after power is turned on, and after that, the registration deviation correction is performed. 3. The image density correction timing of the image density correction means is after power is turned on, and after that, the registration deviation correction is performed at a predetermined number of print intervals or a predetermined time interval. 1. The image forming apparatus of 1. 4. The image density correction timing of the image density correction means is after power is turned on, and after that, the registration deviation is corrected according to the time from the start to the return to the power saving mode for reducing the device power in the standby mode. The image forming apparatus according to claim 1, wherein it is determined whether or not to perform. 5. The image density correction timing by the image density correction means is after power is turned on, and after that, whether or not the registration shift correction is performed according to the setting contents of the power saving mode for reducing the device power in the standby state. The image forming apparatus according to claim 1, wherein 6. The image forming apparatus according to claim 1, wherein the registration deviation correction is not performed when the color setting of the image forming apparatus is set to the black monochromatic mode, or when it is determined that the image is a black monochromatic image output. . 7. The image density correction timing by the image density correction means is after power is turned on, and after that, whether or not the registration deviation correction is performed according to the in-machine temperature detected by the temperature detection means for detecting the in-apparatus temperature. The image forming apparatus according to claim 1, further comprising: 8. The image density correction timing of the image density correction means is after power is turned on, and after that, whether the registration shift correction is performed according to the human body detection result detected by detecting the presence or absence of a human body near the apparatus. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not the image forming apparatus is not included.