JP2003066678A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To put respective color photoreceptor drums of an image forming apparatus in phase with one another in a short time. SOLUTION: The device has an intermediate transfer belt 8 which can abut against the photoreceptor drums 1 where electrostatic latent images corresponding to respective color toner images are formed and to which the color toner images developed on the photoreceptor drums 1 are put one over another and transferred, a photoreceptor body driving gear which rotates the photoreceptor drums 1, a cam 15 which has 1st cam projections 15a and 2nd cam projections 15b in mutually different shapes and rotates together with the photoreceptor drums 1 and the photoreceptor body driving gear, a subordinate part 17 which is cyclically displaced by the rotation of the cam 15, and a sensor 18 which detects the displacement position of the subordinate part 17, and puts the photoreceptor drums in phase with one another by using 1st pulses a1 and b1 and 2nd pulse a2 and b2 which are generated by the 1st cam projections 15a and 2nd cam projections 15b detected by the sensor 18 via the subordinate part 17 and differ in width from each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus having an endless intermediate transfer member, and more particularly to a technique effectively applied to prevent color misregistration in a color image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus adopting an electrophotographic system, a photoconductor, which is an image carrier, is charged by a charger, and the charged photoconductor is irradiated with light according to image information. An image is formed, the latent image is developed by a developing device, and the developed toner image is transferred to a recording medium to form the image.

On the other hand, there are provided a plurality of image forming stations for executing the above-mentioned image forming processes in accordance with colorization of images, and toner images of respective colors of cyan image, magenta image, yellow image, and preferably black image are respectively provided. A tandem-type color image forming apparatus has also been proposed which forms a full-color image by superposing these toner images on an intermediate transfer member having an endless shape at the transfer position of each photosensitive member.

Since such a tandem type color image forming apparatus has an image forming section for each color,
It is advantageous for speeding up.

FIG. 6 is an explanatory view showing the relationship between the drive roller, the photosensitive member and the photosensitive member pitch in the conventional image forming apparatus. Since the drive roller for rotating the intermediate transfer member rotates eccentrically, the speed unevenness inevitably occurs in the intermediate transfer member.

Therefore, in FIG. 6, the relationship between the outer diameter D ₁ of the drive roller and the pitch L of the photosensitive member is L = πD _1, and the outer diameter D ₂ of the photosensitive member and the pitch L of the photosensitive member are L = By having a relationship with πD ₂ , phase matching is performed so that the transfer timing of the toner image from each color photoconductor to the intermediate transfer body in the speed variation pattern of the intermediate transfer body is matched, and each color photoconductor is superimposed on the intermediate transfer body. The color shift between the transferred color toner images is suppressed to the minimum.

According to this, if the pitch of the photoconductor is narrowed in order to miniaturize the apparatus, the outer diameter D _{2 of the} photoconductor also becomes smaller, but in most cases, the relationship of L = πD ₂ is broken,
L <πD ₂ results. Then, the phases of the photoconductors of the respective colors described above become out of phase with each other, and a color shift occurs.

Therefore, in order to narrow the pitch of the photoconductors and prevent the color misregistration by matching the phases, the amount of color misregistration is measured by using a sensor, and the drive motor for rotating and driving each color photoconductor is controlled. The phase was corrected individually.

[0009]

However, in such a technique, it takes a long time for the phase adjustment, so that the waiting time until the start of printing becomes long and the comfortable operability is impaired.

Therefore, an object of the present invention is to provide an image forming apparatus capable of performing phase alignment of photoconductors of respective colors in a short time.

[0011]

In order to solve this problem, the image forming apparatus of the present invention is arranged in a row so that the central axes of rotation thereof are parallel to each other and rotated in the circumferential direction, and toner images of respective colors are formed. And a plurality of photoconductors on which the electrostatic latent images corresponding to the respective photoconductors are formed, and toners of respective colors developed on the photoconductors, which are provided so as to be able to contact the photoconductors and are supported by a plurality of rollers to rotate around the circumference. An endless intermediate transfer body on which images are superimposed and transferred onto each other to form a color toner image, and a photosensitive body that is mounted on the rotation shaft of the photoconductor and that rotates the photoconductor by transmitting the rotational force of a drive motor. A body drive gear, a first cam lobe and a second cam lobe having mutually different shapes, which are respectively mounted on the rotation shafts of the photoconductors, and which rotate together with the photoconductors and the photoconductor drive gears; Against the cam of And a follower portion that is periodically displaced by the rotation of the cam, and a sensor that is provided corresponding to each follower portion and that detects the displacement position of the follower portion. Phase adjustment between the plurality of photoconductors by using the first pulse and the second pulse having different widths respectively generated by the first cam crest and the second cam crest detected by the sensor via It's something that you do.

As described above, since the phase of the photoconductor is detected twice per rotation, the phase of the photoconductor of each color can be aligned in a short time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is an electrostatic latent image corresponding to a toner image of each color, which is arranged in a row so that the central axes of rotation are parallel to each other and is rotated in the circumferential direction. A plurality of photoconductors on which images are formed, respectively, and the toners of the respective colors developed on the photoconductors are superposed on each other and are provided so as to be able to contact the photoconductors and supported by a plurality of rollers to rotate around. An endless intermediate transfer member that is transferred to form a color toner image, and a photoconductor drive gear that is mounted on the rotation shaft of the photoconductor and that rotates the photoconductor by transmitting the rotational force of a drive motor, First cam ridges and second cam ridges having different shapes are formed on the respective shafts and mounted on the rotation shafts of the photoconductors. The cams rotate together with the photoconductors and the photoconductor drive gears. Provided and cam rotation A follower unit for more periodically displaced,
A first cam crest and a second cam crest that are provided corresponding to each follower part and that have a sensor for detecting the displacement position of the follower part, and that are detected by the sensor via the follower part. An image forming apparatus for performing phase alignment between a plurality of photoconductors by using a first pulse and a second pulse having mutually different widths. Phase detection of the photoconductors is performed twice per rotation. Therefore, it has an effect of enabling the phase alignment of the photoconductors of the respective colors in a short time.

According to a second aspect of the present invention, in the first aspect of the invention, an image is formed in which the first cam crest and the second cam crest are formed at positions facing each other in the radial direction. Since it is a forming apparatus and the phase detection of the photoconductor is performed twice in one rotation, it has an effect that the phase alignment of the photoconductors of respective colors can be performed in a short time.

According to a third aspect of the present invention, in the invention according to the first or second aspect, the pulse generated in one of the photoconductors and the pulse generated in the other photoconductor immediately after the pulse are generated. In the case of the first pulse or the second pulse of the same type, phase matching is performed by the time difference between these two pulses, and the pulse generated in one photoconductor and the other photoconductor immediately after the pulse are generated. In the case where the types of pulses generated in the above are different from each other, due to the time difference between these two pulses, in the other photoconductor which is the same as the pulse generated in one photoconductor from the pulse generated in the other photoconductor This is an image forming apparatus that performs phase adjustment by correcting the time until the generated pulse, and the phase of the photoconductor is detected twice in one rotation. In, it has an effect that it becomes possible to perform a phase alignment of each color photoreceptor in a short time.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the photosensitive member on which the yellow, magenta and cyan toner images are formed is the first drive motor and the black is black. The photoconductor on which the toner image is formed is rotatably driven by the second drive motor, and the phase between the photoconductor on which the yellow, magenta or cyan toner image is formed and the photoconductor on which the black toner image is formed. This is an image forming apparatus that performs alignment, and since the phase detection of the photoconductor is performed twice in one rotation, the phase alignment of the photoconductors of the respective colors can be performed in a short time.

A fifth aspect of the present invention is the drive motor according to the first, second or third aspect of the invention, in which the photoconductors on which yellow, magenta, cyan and black toner images are formed are different from each other. An image forming apparatus that is rotationally driven and forms a toner image of yellow, magenta, cyan, and black, and performs phase matching between the photoconductors. The phase detection of the photoconductors is performed twice in one rotation. Therefore, there is an effect that it becomes possible to perform the phase alignment of the photoconductors of the respective colors in a short time.

FIG. 1 shows an embodiment of the present invention.
~ It demonstrates using FIG. In addition, in these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is an explanatory view showing a configuration of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view showing a main part of the image forming apparatus of FIG. 1, and FIG. 3 is an image forming apparatus of FIG. Waveform diagram showing an example of a pulse for phase matching by
FIG. 4 is a waveform diagram showing another example of a pulse for phase matching by the image forming apparatus of FIG. 1, and FIG. 5 is a waveform diagram showing an example of a pulse for phase matching by the image forming apparatus as a comparative example. .

As shown in FIG. 1, the image forming apparatus of the present embodiment has four image forming stations Pa, Pb, P.
c and Pd are arranged, and each image forming station P
Each of a, Pb, Pc, and Pd has a photoconductor drum (photoconductor) 1a, 1b, 1c, and 1d that rotates in the circumferential direction as an image carrier. The photosensitive drums 1a, 1b, 1c, 1d
Are arranged in a row so that their rotation center axes are parallel to each other.

Around the photosensitive drums 1a, 1b, 1c, 1d, charging means 3a, 3b for uniformly charging the surfaces of the photosensitive drums 1a, 1b, 1c, 1d to a predetermined potential.
3c, 3d, charged photosensitive drums 1a, 1b, 1
Exposure light beam 4 corresponding to image data of a specific color on c and 1d
Exposure means 4 for irradiating K, 4C, 4M and 4Y to form an electrostatic latent image, and electrostatic latent images formed on the photoconductor drums 1a, 1b, 1c and 1d are visualized to form a toner image. The developing means 5a, 5b, 5c, 5d, the driving roller 9a and the driven roller 9b are belt-supported by the photosensitive drums 1a, 1a.
An endless intermediate transfer belt (intermediate transfer member) 8 on which toner images of respective colors visualized on b, 1c, and 1d are transferred and superposed on each other to form a color toner image. Transfer means 6a, 6b, 6 for transferring an image
c, 6d, cleaning means 7a, 7b for removing residual toner remaining on the photoconductor drums 1a, 1b, 1c, 1d after transferring the toner image from the photoconductor drums 1a, 1b, 1c, 1d to the intermediate transfer belt 8. , 7c, 7d are arranged respectively.

Here, the photosensitive drums 1a, 1b, 1c,
The intermediate transfer belt 8 provided so as to be capable of contacting 1d is rotated in the direction of arrow A by the drive roller 9a in the illustrated case. The image forming stations Pa, Pb,
In Pc and Pd, a black image, a cyan image,
A magenta image and a yellow image are formed. Then, the monochromatic images of the respective colors formed on the photoconductor drums 1a, 1b, 1c, 1d are sequentially superposed and transferred onto the intermediate transfer belt 8 to form a full-color image. Here, the image is formed in the order of the yellow image, the magenta image, the cyan image, and the black image. Therefore, the yellow image is first transferred onto the intermediate transfer belt 8, and the magenta image, the cyan image, and the yellow image are transferred to the yellow image. Black images are transferred one after another.

At the lower part of the apparatus, a paper feed cassette 12 in which a sheet material 11 such as printing paper is stored is provided.
Then, the sheet material 11 is sent from the sheet feeding cassette 12 by the sheet feeding roller 10 to the sheet conveying path one by one.

On the paper conveying path, the intermediate transfer belt 8 comes into contact with the outer peripheral surface of the intermediate transfer belt 8 for a predetermined amount.
A sheet material transfer roller 13 that transfers the color image formed on the sheet material 11, and a fixing that fixes the color image transferred on the sheet material 11 to the sheet material 11 by pressure and heat associated with the rotation of nip of the roller. The container 14 is arranged.

In the image forming apparatus having such a structure,
First, the latent image of the yellow component color of the image information is formed on the photosensitive drum 1d by the charging device 3d and the exposure device 4 of the image forming station Pd. This latent image is visualized as a yellow toner image by the developing means 5d having yellow toner, and transferred as a yellow toner image onto the intermediate transfer belt 8 by the transfer means 6d.

On the other hand, while the yellow toner image is being transferred to the intermediate transfer belt 8, a latent image of magenta component color is formed at the image forming station Pc, and then the developing means 5 is formed.
In c, the magenta toner image by the magenta toner is visualized. Then, the magenta toner image is transferred onto the intermediate transfer belt 8 where the transfer of the yellow toner image is completed at the image forming station Pd at the image forming station Pc.
Transferred and is superimposed on the yellow toner image.

Thereafter, the cyan toner image and the black toner image are similarly formed, and when the superimposing of the four color toner images on the intermediate transfer belt 8 is completed, the paper is fed from the paper feeding cassette 10 by the paper feeding roller 10. The toner images of four colors are collectively transferred onto the fed sheet material 11 by the sheet material transfer roller 13. Then, the transferred toner image is heated and fixed on the sheet material 11 by the fixing device 14, and a full-color image is formed on the sheet material 11.

The photosensitive drums 1a, 1b, 1c and 1d, which have been transferred, are cleaned by the cleaning means 7a,
The residual toner is removed by 7b, 7c, and 7d, and the toner is prepared for the next image formation to be performed subsequently.

In such an image forming apparatus, the photosensitive drums 1b, 1c and 1d on which yellow, magenta and cyan toner images are formed are already phase-matched at the assembly stage and are gear-coupled to each other. It is adapted to be rotationally driven by a common first drive motor (not shown). The photosensitive drum 1a on which a black toner image is formed is rotationally driven by a second drive motor (not shown).

The phase matching is performed by correcting the color shift, by matching the phases of the shake components of the photoconductor drums 1b, 1c, 1d, or by matching the phases of the shake components of the photoconductor drive gear described later. By
It can be carried out. However, these may be appropriately used in combination, and further, a method other than these may be used.

The photoconductor drums 1b, 1c, 1d are provided with photoconductor drive gears for transmitting the rotational force of the first drive motor to rotate the photoconductor drums 1b, 1c, 1d. , 1d on the rotation axis. In addition, a photoconductor driving gear that rotates the photoconductor drum 1a by transmitting the rotational force of the second drive motor is attached to the photoconductor drum 1a on the rotation shaft of the photoconductor drum 1a.

Therefore, the photosensitive drums 1b, 1c, on which the yellow, magenta and cyan toner images are formed,
There is no phase shift between 1d, but these photoconductor drums 1b, 1c, 1d and the photoconductor drum 1a on which a black toner image is formed are driven by different drive motors. Therefore, or because only the photosensitive drum 1a is rotationally driven in order to print only black, a phase shift occurs.

Here, as shown in FIG. 2, the photosensitive drums 1a, 1 on which cyan and black toner images are formed.
The photoconductor driving gears 2a and 2b attached to the photoconductor drive gears 2a and 2b are attached to the photoconductor drums 1a and 1b and the photoconductor driving gears 2a and 2b.
Cams 15 that rotate together are mounted on the rotation shafts of the photoconductor drums 1a and 1b, respectively.

Therefore, the photosensitive drums 1b, 1c, 1
The phase shift between the photosensitive drum 1a and the photosensitive drum 1a is
It is corrected by matching the phases of b and the photosensitive drum 1a.

The phase alignment is performed by aligning the phase of the photoconductor drum 1d on which the yellow toner image is formed with the photoconductor drum 1a on which the black toner image is formed, or by forming a magenta toner image. It is also possible to match the phases of the photoconductor drum 1c that forms the black toner image and the photoconductor drum 1a on which the black toner image is formed.

Further, the photosensitive drums 1a, 1 on which yellow, magenta, cyan and black toner images are formed.
An image forming apparatus in which b, 1c, and 1d are independently driven to rotate by different drive motors may be used.
In this case, the photosensitive drums 1a, 1b, on which the yellow, magenta, cyan, and black toner images are formed,
Phase matching between 1c and 1d is performed.

Now, in FIG. 2, the photosensitive drum driving gears 2a and 2b attached to the photosensitive drums 1a and 1b on which cyan and black toner images are formed respectively include the photosensitive drums 1a and 1b and the photosensitive drum driving gears. Cams 15 that rotate with 2a and 2b are mounted on the rotation shafts of the photoconductor drums 1a and 1b, respectively. The photosensitive drums 1c, on which the yellow and magenta toner images are formed,
1d has the same configuration, but is not shown here.

The cam 15 is formed with a first cam lobe 15a and a second cam lobe 15b having mutually different shapes at positions facing each other in the radial direction. In addition, in the present embodiment, the first cam crest 15a and the second cam crest 15b are formed at the radially opposed positions as described above,
It does not have to be such an arrangement.

Further, as shown in the figure, a follower portion 17 which is periodically displaced by the rotation of the cam 15 and a photo sensor (sensor) 18 which detects the displaced position of the follower portion 17 are provided. Note that a sensor other than the photo sensor can be used as long as the displaced position of the follower portion 17 can be detected.

With this structure, in the present embodiment, the mutual widths generated by the first cam crest 15a and the second cam crest 15b detected by the photo sensor 18 via the follower portion 17 are mutually different. Phase matching is performed by using different pulses (first pulse, second pulse).

Here, as a comparative example, phase matching using a pulse generated by a cam in which only one cam crest is formed will be described.

In the present embodiment, it is described that the phases match when the time difference of the pulses between the photoconductor drums for phase matching disappears. May match.

As shown in FIG. 5, assuming that the pulses generated by the rotation of the photosensitive drum A and the photosensitive drum B are a and b, respectively, since there is one cam crest, each pulse a, One b will be generated in one round. For the phase matching by the pulse, for example, if the pulse a is generated on the photoconductor drum A, the time difference C between the pulse a and the pulse b generated on the photoconductor drum B immediately after that is taken so that it becomes zero. (Or, the rising edge is shifted by a predetermined time). Then, when the number of cams is one, the time difference C is maximum and the photosensitive drum 1
It takes almost the same time as the rotation, and it takes time to adjust the phase.

Next, phase matching in the image forming apparatus of this embodiment will be described.

Here, among the pulses generated on the photosensitive drum A, the narrow pulse is the first pulse a ₁ and the wide pulse is the second pulse a ₂ . Further, among the pulses generated by the photoconductor drum B, the narrow pulse is the first pulse b ₁ and the wide pulse is the second pulse b ₂ . Since the photoconductor drum A and the photoconductor drum B are aligned with each other, these correspond to the photoconductor drum 1a and the photoconductor drum 1b in FIGS. 1 and 2, respectively. However, when the alignment between the other photoconductor drums is performed, they correspond to the photoconductor drum A and the photoconductor drum B. Therefore, the photoconductor drum A and the photoconductor drum B are shown in FIGS. It does not correspond to a specific photosensitive drum.

First, the phase matching in the case where the pulse generated by the photosensitive drum A and the pulse generated immediately after that by the photosensitive drum B are the same pulse will be described. Note that, here, the pulses generated by the photoconductor drums A and B are the first pulses a ₁ and b ₁ .

As shown in FIG. 3, in this case, since the time difference C between these two pulses a ₁ and b ₁ becomes the phase difference, phase matching is performed at this time difference C. That is, the first pulse a ₁ of the photosensitive drum A and the first pulse a ₁ of the photosensitive drum B are
The rotation of the photosensitive drums A and B is controlled so that there is no time difference from the pulse b ₁ of the above.

Next, the phase matching in the case where the pulse generated by the photosensitive drum A and the pulse generated immediately after that by the photosensitive drum B are different from each other will be described. Here, the pulse generated by the photosensitive drum A is the first pulse a ₁ and the pulse generated by the photosensitive drum B is the second pulse b ₂ .

As shown in FIG. 4, in this case, at the time difference C between these two pulses a ₁ and b ₂ , from the second pulse b ₂ generated on the photosensitive drum B to the photosensitive drum B.
The phase adjustment is performed by adding the correction of the time D up to the _first pulse b ₁ which is the pulse generated in 1.

As described above, according to the present embodiment, the phase detection of the photoconductor drums is performed twice in one rotation, so that the phase alignment of the photoconductor drums of each color can be performed in a short time. It becomes possible (time D is constant).

Further, since the rotation amount of the photoconductor due to the phase adjustment is minimized, the life of the photoconductor drum, which is a consumable item, can be extended.

It should be noted that the image formed on the photosensitive drum A is
First pulse a₁(Or the second pulse a₂) Width and others
The first pulse b generated on the other photosensitive drum B
₁(Or the second pulse b₂) Width is not mutually the same
You don't have to. In other words, it is generated on the photoconductor drums A and B.
The first pulse a₁, B₁Width of the second pulse a ₂，
b₂Of the photosensitive drums A and B on both sides are different from each other.
The first pulse at₁, B₁And the second pulse a₂, B₂
Have the same width definition (that is, the first pulse a₁, B₁Is the
2 pulse a₂, B₂Wider (or narrower) than
Person).

Here, the determination of the width of the pulse width is made by, for example, the average width of the first pulse a ₁ being 50 ms and the second pulse a _{2 being}
If the average width of the
It can be performed depending on whether the detected pulse width is wider or narrower than this threshold.

Therefore, even if the pulse widths generated by a plurality of photosensitive drums vary, the determination of the pulse widths will not be hindered.

[0055]

As described above, according to the present invention, since the phase detection of the photoconductor is performed twice per rotation, it is possible to perform the phase alignment of the photoconductors of respective colors in a short time. The effective effect of becoming is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a main part of the image forming apparatus of FIG.

3 is a waveform diagram showing an example of a pulse for phase matching by the image forming apparatus of FIG.

4 is a waveform chart showing another example of pulses for phase matching by the image forming apparatus of FIG.

FIG. 5 is a waveform chart showing an example of a pulse for phase matching by an image forming apparatus as a comparative example.

FIG. 6 is an explanatory diagram showing a relationship between a drive roller, a photoconductor, and a photoconductor pitch in a conventional image forming apparatus.

[Explanation of symbols]

1b, 1c, 1d photoconductor drum (photoconductor) 2b Photoconductor drive gear 8 Intermediate transfer belt (intermediate transfer member) 15 cams 15a Kam mountain 15b Kam mountain 17 Follower 18 sensor (photo sensor)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoki Maki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Junya Yamauchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 2H027 DA22 EB06 ED02 EE01 EE03                       EE04                 2H030 AA01 AB02 AD17 BB42 BB63                       BB71                 2H035 CA07 CB01 CG01 CG03                 2H071 CA02 CA05 EA18

Claims (5)

[Claims] 1. A plurality of photoconductors, which are arranged in a row so that their central axes of rotation are parallel to each other and rotate in the circumferential direction, to form electrostatic latent images corresponding to toner images of respective colors, respectively; An endless shape which is provided so as to be able to contact the body and is supported by a plurality of rollers in a band-wise manner to rotate, and the toner images of the respective colors developed on the photoconductor are superposed on each other and transferred to form a color toner image. Of the intermediate transfer member, a photoconductor driving gear that is mounted on the rotation shaft of the photoconductor and rotates the photoconductor by transmitting the rotational force of a driving motor, and a first cam crest having a different shape and Second cam ridges are formed and are respectively mounted on the rotation shafts of the photoconductors, and the cams rotate together with the photoconductors and the photoconductor drive gears, and the cams are provided corresponding to the respective cams. In rotation A follower section that is displaced more periodically, and a sensor that is provided corresponding to each of the follower sections and that detects a displacement position of the follower section, are provided by the sensor through the follower section. Phase matching between the plurality of photoconductors is performed using the first pulse and the second pulse having different widths respectively generated by the detected first cam lobe and the second cam lobe. An image forming apparatus characterized by the above. 2. The image forming apparatus according to claim 1, wherein the first cam lobe and the second cam lobe are formed at positions facing each other in the radial direction. 3. The first pulse or the second pulse in which the type of the pulse generated in one of the photoconductors and the type of the pulse generated in the other photoconductor immediately after the pulse are the same. In the case where the phase is adjusted by the time difference between these two pulses, and the type of the pulse generated in one of the photoconductors and the type of the pulse generated in the other photoconductor immediately after the pulse are different from each other. To the time difference between these two pulses, from the pulse generated in the other photoconductor to the pulse generated in the other photoconductor that is the same as the pulse generated in the one photoconductor. The image forming apparatus according to claim 1, wherein phase adjustment is performed by adding time correction. 4. The photoconductor on which yellow, magenta, and cyan toner images are formed is rotationally driven by a first drive motor, and the photoconductor on which a black toner image is formed is rotationally driven by a second drive motor, respectively. The image according to claim 1, 2 or 3, wherein the photoconductor on which a yellow, magenta or cyan toner image is formed and the photoconductor on which a black toner image is formed are phase-matched to each other. Forming equipment. 5. The photoconductor on which yellow, magenta, cyan, and black toner images are formed is rotationally driven by different drive motors to form yellow, magenta, cyan, and black toner images. The image forming apparatus according to claim 1, 2 or 3, wherein mutual phase matching is performed.