JP2001350387A - Image forming device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means capable of moving at least one of rotating bodies (photoreceptor drums) integrally with a belt without any slippage even when there is load variation in the rotating bodies which are eccentric or uneven in diameter. SOLUTION: The image forming device, by which the rotating bodies (photoreceptor drums) 901, 902, 903 and 904 are integrally moved by driving a carrying belt 915, is provided with a means for highly accurately setting the speed of a load variation correcting control system for canceling the load variation of each rotating body even in the case that the rotating bodies are eccentric or uneven in diameter, and a means for detecting the control error of the control system.

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 and an image forming method, and more particularly, to an image forming apparatus including a photosensitive drum and a belt such as a transport belt or an intermediate transfer belt for transporting a sheet and an image forming method. With regard to
The control device here can be applied to a general application of a mechanism for integrally moving a rotating body and a belt having eccentricity or variation in diameter.

[0002]

2. Description of the Related Art In recent years, there has been an increasing need for a color image forming apparatus capable of forming a color image. One of image forming apparatuses capable of forming a color image at high speed is an electrophotographic tandem-type image forming apparatus. A conventional example of a tandem type image forming apparatus is disclosed in
There is an invention described in JP-A-81373 or an invention described in JP-A-10-246995.

The invention described in Japanese Patent Application Laid-Open No. 63-81373 and the invention described in Japanese Patent Application Laid-Open No. Hei 10-246959 each include four photosensitive drums, each of which is a photosensitive drum. A scanning unit is provided for scanning a laser beam to write a latent image on the body drum.

[0004] The four photosensitive drums are arranged in parallel in the transport direction of the paper transported by the transport belt. Then, the laser beam emitted from the scanning unit is rotated while scanning (main scanning) in the direction of the rotation axis, and a latent image is written. One line of the latent image written by one main scan is hereinafter referred to as a scan line.

On the surfaces of the four photosensitive drums on which the latent images have been written, Y (yellow), M (magenta), C
Any one of the toners of (cyan) and K (black) is supplied and adheres to the latent image. Therefore, a toner image of any one of the four colors is formed on each of the four photosensitive drum surfaces. The paper is sequentially pressed against the four photosensitive drums on which the toner images are formed. As a result, the toner images of the respective colors are sequentially transferred to the paper to form a color image.

[0006] At this time, if a shift occurs between the scanning lines constituting the toner images of the respective colors in the formed color image, a so-called color shift occurs in the color image, and the image quality is degraded. To prevent color misregistration, refer to
In the invention described in Japanese Patent Application Laid-Open No. 6955, the photosensitive drum is configured to be rotatable, while the annular transport belt is rotationally driven by a motor, and the transport belt is pressed against the photosensitive drum by a pressure roller provided below the transport belt. I do. The four rotating drums rotate following the conveyor belt. At this time, the four photosensitive drums rotate at the same rotational angular velocity because the same rotational force is applied, and form a color image with no positional deviation between the scanning lines.

[0007]

However, in general, the photoreceptor drum often has a slight eccentricity due to the limitation of the assembling accuracy. FIG. 22 is a diagram illustrating a state in which the conveying belt is pressed against the eccentric photosensitive drum 2101 by the pressing roller. The photosensitive drum 2101 shown in the drawing is shown as a cross section orthogonal to a rotation axis perpendicular to the plane of the drawing passing through the point O.

The eccentric photosensitive drum 2101 has a point O
It rotates around the central axis passing through. On the other hand, the transport belt 2102 has a ring shape and moves in the direction of arrow A. The pressure contact roller 2103 contacts the transport belt 2102 from below while being supported by the spring 2104, and presses the transport belt 2102 against the photosensitive drum 2101. A sheet (not shown) is pressed against the photosensitive drum 2101 by a pressing roller 2103 via a conveyor belt 2102. Then, the toner image formed on the surface of the photosensitive drum 2101 is transferred to a sheet.

The distance from the point O of the photosensitive drum 2101 with eccentricity to the peripheral surface changes according to the rotation angle when observed at a fixed point. Therefore, the paper and the photosensitive drum 2
When the center of gravity of the photoconductive drum 2101 is at G1, the pressure contact is made at the press-contact position P1, and when the center of gravity of the photoconductive drum 2101 is at G2, the press-contact is made at the press-contact position P2.

On the other hand, the pressing roller 2103 is
It moves up and down to some extent because it is supported by 4. Since the pressing roller 2103 also has eccentricity, the pressing position changes in a complicated manner, and the influence on the angular velocity of the photosensitive drum 2101 increases.

When the angular velocity of the photosensitive drum 2101 changes, the interval between the scanning lines of the latent image written on the photosensitive drum 2101 becomes non-uniform, and the formed image is distorted. In a tandem-type color image forming apparatus that includes a plurality of photosensitive drums and forms a color image by superimposing multicolor toner images, when the angular velocity of the plurality of photosensitive drums varies, the transfer position of the toner image of each color is changed. , The image quality of the formed image is degraded.

It is also conceivable to estimate the transfer position of the toner image by calculation and adjust the image forming conditions so that the transfer position is adjusted based on the result. But,
If the angular velocity of the photosensitive drum 2101 changes, the transfer position of the toner image cannot be accurately predicted, and the transfer position of the toner image cannot be adjusted by adjusting the image forming apparatus. Therefore, in the image forming apparatus in which the angular velocity of the photosensitive drum changes, the transfer position of the toner image cannot be eliminated by adjusting the image forming conditions, and the image quality cannot be improved.

The tandem type color image forming apparatus includes a writing unit for each photosensitive drum.
However, it cannot be said that the writing timing by each writing unit provided in each photosensitive drum and the characteristics of the optical system always match. For this reason, the writing timing is shifted for each photoconductor drum, and even when there is no eccentricity in each photoconductor drum, the transfer position of the toner image of each color may be shifted.

Further, the radii of the respective photosensitive drums may slightly vary due to the limitation of processing accuracy. In this case also, the transfer position of the toner image of each color is shifted regardless of the eccentricity of each photosensitive drum.

As print quality of higher resolution (1200 dpi or more) is demanded in the future, it is necessary to manufacture a photosensitive drum of extremely high precision in order to solve the above-mentioned problems. Foreseeing future technological advances,
Although it will be possible to improve the processing accuracy of the photosensitive drum to a certain extent, there is a limit to the improvement of the processing accuracy.

The present invention has been made in view of the above points, and the present invention has been made in consideration of the eccentricity and the variation in the radius of the photosensitive drum caused by variations in assembling the photosensitive drum. It is an object of the present invention to provide an image forming apparatus and an image forming method capable of forming a high-quality image by transferring a toner image onto a sheet on a conveyance belt without displacement.

[0017]

The above-mentioned problems can be solved by the following means. That is, the image forming apparatus according to claim 1 includes at least one rotating body that is directly or indirectly pressed against the belt and is driven by the movement of the belt, and a driving roller that drives the belt. An image forming apparatus comprising: a driving roller driving unit that drives the driving roller; a rotating body driving unit that drives the rotating body; a load fluctuation detecting unit that detects a load fluctuation of the belt; Control means for controlling the operation of the driving roller driving means or the rotating body driving means in accordance with a load change.

According to the first aspect of the present invention, there is provided at least one rotating body which is directly or indirectly pressed against an annular belt for conveying a transfer sheet with a sheet interposed therebetween and driven by the movement of the belt. And an image forming apparatus including a driving roller for driving the belt. A driving roller driving unit drives the belt. Further, the rotating body driving means drives the rotating body. The load change detecting means detects a load change applied to the belt.
The control means controls the operations of the driving roller driving means and the rotating body driving means in accordance with the load fluctuation of the belt.

Therefore, the load transmitted from the rotating body to the belt can be detected. Based on the detected result, the driving of the rotating body is controlled, and the belt is controlled so as to oppose the entire load applied to the driving roller. Slip can be eliminated. Therefore, the image forming apparatus can be easily applied to high-quality printing.

The image forming apparatus according to the second aspect is the first aspect.
In the image forming apparatus according to the above, the load detecting means,
The driving roller driving means is provided in a control means for controlling the driving roller driving means.

According to the second aspect of the present invention, since the detection is performed without attaching a special detector, the load applied to the belt can be detected with a simple device.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the load fluctuation detecting unit detects a current supplied to the driving roller driving unit. It is characterized by being.

According to the third aspect of the present invention, the load on the belt can be detected only by detecting the current supplied to the drive roller driving means, so that the load on the belt can be detected with a simple device.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the rotator driving means detects a load variation of the belt. It is characterized by having identification signal generating means for generating an identification signal for facilitation.

According to the present invention, since the identification signal generating means for generating the identification signal for facilitating the detection of the fluctuation of the load of the belt is provided, the load generated by any of the rotating bodies with a simple configuration. It can be easily detected whether it is a fluctuation.

According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the identification signal is a sine wave.

According to the fifth aspect of the present invention, since the identification signal is a sine wave, the load variation can be easily detected with a simple configuration such as a band-pass filter.

In the image forming apparatus according to a sixth aspect, in the image forming apparatus according to the fourth or fifth aspect, the identification signal generating means adds the identification signal at a different timing for each of the rotating bodies. It is characterized by the following.

In the invention according to claim 6, since the identification signal is added at a different timing for each of the rotating bodies, the load fluctuation of each rotating body can be easily identified.

According to a seventh aspect of the present invention, in the image forming apparatus of the fourth or fifth aspect, the identification signal is a sine wave having a different frequency for each of the rotating bodies. I do.

In the invention according to the seventh aspect, since the identification signal is a sine wave having a different frequency for each of the rotating bodies, it is possible to easily and simultaneously identify the load fluctuation of each rotating body.

According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, any one of the belt, the driving roller driving unit, and the rotating body driving unit is used. It is characterized in that a means for applying an inertial load to the crab is added.

The invention according to claim 8 is characterized in that a means for applying an inertial load to any of the belt, the driving roller driving means, and the rotating body driving means is added, so that the speed fluctuation of the belt caused by the fluctuation of the load. Can be lowered, and stable control can be easily performed so as to reduce the slip of the belt.

An image forming apparatus according to a ninth aspect is at least one rotating body which rotates while being pressed directly or indirectly on the belt, and at least one of a moving speed of the belt and a speed related to the rotating body. A system having a speed detecting means and a control means for detecting one of them, wherein in a system having the speed detecting means and the control means, the moving speed of the belt and the rotating speed of the rotating body are integrated with the belt and the rotating body. A speed setting means for setting a moving speed is provided.

According to the ninth aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if the shapes of the respective rotators vary.

According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the speed setting means controls a speed of the rotating body control means according to a diameter (radius) of the rotating body. It is a means for generating a reference signal to be determined.

According to the tenth aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if the radiators vary in radius. .

An image forming apparatus according to claim 11 is the image forming apparatus according to claim 9 or 10,
The speed setting means generates speed reference information based on information obtained from the speed detecting means of the rotating body and the belt moving speed detecting means.

According to the eleventh aspect of the present invention, even if a radius measuring means for a rotating body is not newly provided, a means for detecting an existing rotation angle and detecting a speed and a distance for moving the belt are measured. Since the speed control reference signal can be generated based on the information obtained by the means for detecting the moving speed, a simple image forming apparatus can be formed.

According to a twelfth aspect of the present invention, in the image forming apparatus of the ninth, tenth, or eleventh aspect, the speed setting means includes a pulse signal output from the speed detecting means. And a pulse signal for synchronizing with an analog signal or an analog reference signal for comparison with an analog signal generated from the speed detecting means of the rotating body.

According to the twelfth aspect of the present invention, even if the number of output pulses of the speed detector by the rotation angle detector is one per rotation, the output is compared with the analog signal continuously output from the speed detecting means of the rotating body. The control can be performed by generating a rotation speed reference signal. In other words, the influence of the radius variation of the rotating body is suppressed by comparing pulse signals, and stable control can be performed by comparing analog signals, so that stable rotating body speed control in which the belt does not slip can be provided.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, a load on the belt caused by a control error of the rotating body control means is provided. The fluctuation is corrected by the speed setting means based on information obtained by the load fluctuation detecting means.

According to the thirteenth aspect of the present invention, the control error of the rotating body can be directly detected as a load applied to the belt, so that the correction can be performed with higher accuracy. Therefore, a device that is less slippery can be constructed.

According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the first to thirteenth aspects, a contact portion between the belt and the rotator includes a contact portion of the rotator. It is characterized in that it has a configuration that is a vertex in the belt direction in a circular cross section.

According to the present invention, when the rotating body is eccentric, a contact portion between the belt and the rotating body changes in a belt moving direction or a direction perpendicular to the belt moving direction. When moving at a speed, the rotational angular velocity of the rotator becomes constant. Thus, if a plurality of the rotating bodies are provided, a function of detecting the moving position of the belt or detecting the rotation angle of the belt driving roller to detect the moving speed may provide the plurality of rotating bodies with a simple one.
The rotation angle or speed of the rotating body can be predicted with high accuracy by using a detector that detects only one shot in the circumference. This can be said to be the same even if the radius of the rotating body further varies. Therefore, in the mechanism system in which the conditions here are satisfied, the above control can be realized with higher accuracy even if the rotating body has eccentricity or variation in diameter, so that a stable slip-free device can be realized.

According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to fourteenth aspects, the rotating body is a photosensitive drum on which a latent image is written. The belt is a conveyance belt that presses the paper against the photosensitive drum, transfers a toner image formed based on the written latent image to the paper, and conveys the paper;
Alternatively, the belt is an intermediate transfer belt for directly transferring a toner image formed based on a latent image written on the photosensitive drum by pressing the toner image against the photosensitive drum.

According to the fifteenth aspect of the present invention, it is possible to eliminate slippage between the photosensitive drum and the belt, between the photosensitive drum and the sheet, or between the sheet and the belt. However, if the belt moves at a constant speed, the rotational angular velocity of the photosensitive drum becomes constant, so that it is possible to stably and easily realize an image without image distortion or color shift.

According to another aspect of the present invention, there is provided an image forming method comprising: at least one rotating member which is directly or indirectly pressed against a belt and is driven by the movement of the belt; and a driving roller for driving the belt. A driving roller driving step for driving the driving roller, a rotating body driving step for driving the rotating body, and a load for detecting a load variation of the belt. And a control step of controlling an operation of the driving roller or the rotating body according to a load change of the belt.

According to a sixteenth aspect of the present invention, there is provided at least one rotating member which is directly or indirectly pressed against an annular belt for conveying a transfer sheet with a sheet interposed therebetween and is driven by the movement of the belt. And an image forming method for controlling an image forming apparatus including a driving roller for driving the belt. In the driving roller driving step, the belt is driven. In the rotating body driving step, the rotating body is driven. In the load change detecting step, a load change applied to the belt is detected. In the control step, the operation of the driving roller and the rotating body is controlled according to the load variation of the belt.

Therefore, the load transmitted from the rotating body to the belt can be detected, and the driving of the rotating body is controlled based on the detected result, and the belt is controlled so as to oppose the entire load applied to the driving roller. Slip can be eliminated. Therefore, the image forming method can be easily applied to high quality printing.

According to a seventeenth aspect of the present invention, in the image forming method of the sixteenth aspect, in the load variation detecting step, a current supplied to drive the driving roller is detected. And

According to the seventeenth aspect of the present invention, only the current supplied to drive the drive roller is detected,
Since the load on the belt can be detected, the load on the belt can be detected with a simple device.

The image forming method according to claim 18 is the image forming method according to claim 16 or 17, wherein in the driving step of the rotating body, identification for facilitating detection of load fluctuation of the belt is performed. Generating a signal.

According to the eighteenth aspect of the present invention, since the identification signal for facilitating the detection of the load fluctuation of the belt is generated, it is possible to easily detect which rotating body the load fluctuation is generated from with a simple configuration. it can.

According to a nineteenth aspect of the present invention, in the image forming method of the eighteenth aspect, the identification signal is a sine wave.

According to the nineteenth aspect of the present invention, since the identification signal is a sine wave, the load variation can be easily detected with a simple configuration such as a band-pass filter.

According to a twentieth aspect of the present invention, in the image forming method according to the eighteenth or nineteenth aspect, the identification signal is added at a different timing for each of the rotating bodies.

According to the twentieth aspect of the present invention, since the identification signal is added at a different timing for each of the rotating bodies, the load fluctuation of each rotating body can be easily identified.

According to a twenty-first aspect of the present invention, in the image forming method according to the eighteenth or nineteenth aspect, the identification signal is a sine wave having a different frequency for each rotating body. I do.

In the invention according to claim 21, since the identification signal is a sine wave of a different frequency for each of the rotating bodies, it is possible to easily and simultaneously identify the load fluctuation of each rotating body.

According to a twenty-second aspect of the present invention, in the image forming method according to any one of the sixteenth to twenty-first aspects, any one of the belt, the driving roller driving unit, and the rotating body driving unit is used. A step of applying an inertial load to the crab is added.

According to a twenty-second aspect of the present invention, a step of applying an inertial load to one of the belt, the driving roller driving means, and the rotating body driving means is added, so that the belt speed fluctuation caused by the load fluctuation is added. Can be lowered, and stable control can be easily performed so as to reduce the slip of the belt.

23. An image forming method according to claim 23, wherein the image forming method is for controlling at least one rotating body which rotates while being directly or indirectly pressed against the belt, wherein the moving speed of the belt is controlled. A speed detection step and a control step of detecting at least one of the speeds related to the rotating body, wherein in the system for executing the speed detecting step and the control step, the moving speed of the belt and the rotating speed of the rotating body are determined by the belt. And a speed setting step of setting a speed at which the and the rotating body can move integrally.

The invention according to the twenty-third aspect can prevent the occurrence of slippage between the rotating body and the belt, between the rotating body and the sheet, or between the sheet and the belt, even if the shapes of the rotating bodies vary.

According to a twenty-fourth aspect of the present invention, in the image forming method according to the twenty-third aspect, a reference signal for determining a speed in the rotating body control step according to a diameter (radius) of the rotating body is provided. Characterized in that it occurs.

According to the twenty-fourth aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if the radiators vary in radius. .

According to a twenty-fifth aspect of the present invention, in the image forming method according to the twenty-third aspect or the twenty-fourth aspect, the step of setting the speed is obtained from a step of detecting a speed of the rotating body and a step of detecting the belt moving speed. And generating speed reference information based on the obtained information.

According to the twenty-fifth aspect of the present invention, even if a radius measuring means for the rotating body is not newly provided, a means for detecting an existing rotation angle and detecting a speed and a distance for moving the belt by measuring a distance for moving the belt. Since the speed control reference signal can be generated based on the information obtained by the means for detecting the moving speed, a simple image forming method can be realized.

According to a twenty-sixth aspect of the present invention, in the image forming method according to the twenty-third, twenty-fourth, or twenty-fifth aspect, the speed setting step includes the step of outputting a pulse signal output in the speed detecting step. And a pulse signal for synchronizing with an analog signal or an analog reference signal for comparison with an analog signal generated in the speed detection step.

According to the twenty-sixth aspect of the present invention, even when the number of output pulses of the speed detector by the rotation angle detector is one per rotation, the output is compared with the analog signal continuously output from the speed detector of the rotating body. The control can be performed by generating a rotation speed reference signal. In other words, the influence of the radius variation of the rotating body is suppressed by comparing pulse signals, and stable control can be performed by comparing analog signals, so that stable rotating body speed control in which the belt does not slip can be provided.

According to a twenty-seventh aspect of the present invention, in the image forming method according to any one of the twenty-third to twenty-sixth aspects, the image forming method according to any one of the twenty-third to twenty-sixth aspects is applied to the belt, which is caused by a control error in the rotating body control step. The load fluctuation is corrected in the speed setting step based on information obtained in the load fluctuation detecting step.

According to the twenty-seventh aspect of the present invention, the control error of the rotating body can be directly detected as a load applied to the belt, so that the correction can be performed with higher accuracy and the method becomes less slippery.

[0073]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image forming apparatus and an image forming method according to the present invention will be described below.
The image forming apparatus of the present invention has a circular cross section, a photosensitive drum that rotates about an axis perpendicular to the cross section, and a sheet contacting the photosensitive drum, which is formed on the surface of the photosensitive drum. The image forming apparatus includes a sheet on which the toner image is transferred and a transport belt for transporting the sheet. The contact portion between the conveyor belt or the paper and the photoconductor drum is configured to be a vertex in a direction of the conveyance belt in a circular cross section of the photoconductor drum.

In the embodiment of the present invention, the belt is configured as a transport belt that transports the paper toward the photosensitive drum. In addition, as the belt of the image forming apparatus of the present invention, an intermediate transfer belt that transfers a toner image formed on a photosensitive drum to a surface, and then transfers the image to a sheet can be considered.

Further, the image forming apparatus of the present invention detects a difference between an ideal (as designed) state and an actual state (such as the eccentricity of the photosensitive drum) of the image forming apparatus, and adjusts the image forming conditions according to the difference. Is adjusted so that a high-quality image can be formed. In the first embodiment, the configuration of the image forming apparatus according to the first embodiment will be described first, followed by detection of the state of the image forming apparatus and adjustment of the image forming conditions according to the state of the image forming apparatus.

(Embodiment 1) Configuration of Image Forming Apparatus FIG. 1 is a diagram for explaining a main part of an image forming apparatus according to Embodiment 1. The illustrated image forming apparatus includes a photosensitive drum C101, a photosensitive drum M102, and a photosensitive drum Y1.
03, a tandem image forming apparatus provided with a photosensitive drum K104. Further, the image forming apparatus includes a transport belt 1
15 and the drive roller 1 around which the conveyor belt 115 is wound
06, the driven roller 105, and the tension roller 114
And rollers 111, 112, and 113. Below the photoconductor drum C101, the photoconductor drum M102, the photoconductor drum Y103, and the photoconductor drum K104, transfer corona chargers 107 and 108 for transferring a toner image formed on the surface of the photoconductor drum onto paper are provided. 10
9 and 110 are provided, respectively.

The image forming apparatus according to the first embodiment includes an image reading unit such as a scanner, a paper feeding unit including a paper feeding cassette,
The image forming apparatus includes a fixing unit that fixes the toner image on the sheet and a sheet discharging unit. Since the above configuration is a known configuration, illustration and description are omitted.

The photosensitive drum C101 and the photosensitive drum M1
02, photosensitive drum Y103, photosensitive drum K104
Each includes a writing unit that scans a surface with a laser beam to write a latent image, a developing unit that supplies toner to the latent image to form a toner image, a cleaner, a charger, and the like. Since the above configuration is also a known configuration, illustration and description are omitted. The developing device provided on the photosensitive drum C101 supplies cyan toner. The developing device provided on the photosensitive drum M102 supplies magenta toner. The developing device provided on the photosensitive drum Y103. The developing device supplies yellow toner, and the developing device provided on the photosensitive drum K104 supplies black toner.

The photosensitive drum C101 and the photosensitive drum M1
02, photosensitive drum Y103, photosensitive drum K104
Are photosensitive drums each having a circular cross section and rotating about an axis perpendicular to the cross section. Conveyor belt 115
Reference numeral denotes an endless transport belt for bringing a paper (not shown) into contact with each photosensitive drum and transferring a toner image formed on the surface of each photosensitive drum. Conveyor belt 11 shown
5 moves at a constant speed V in the direction of the arrow.

The tension roller 114 is rotatable, and is urged against the transport belt 115 by a spring 114a as shown in FIG. The transport belt 115 is brought into contact with a part of the photosensitive drum with an appropriate tension by the spring pressure of the spring 114a.

In the image forming apparatus shown in FIG. 1, rollers 111, 112, and 113 are provided between the photosensitive drums. Photoconductor drum C101, photoconductor drum M1
02, the photosensitive drum Y103 and the photosensitive drum K104 are not provided with rollers for pressing the transport belt 115 against each other.

For this reason, the transfer position (transfer position) changes due to the eccentricity of the photosensitive drum, but the contact portion (transfer position) between the conveyor belt or paper and the photosensitive drum.
Is substantially the top of the circular cross section of the photosensitive drum in the direction of the conveyor belt.

Further, the transport belt 115 at the transfer position
Since there is no roller that comes into contact with the photosensitive drum, there is no influence from variations in the pressed position of the pressing roller, so that the rotational angular velocity of the photosensitive drum does not change.

FIG. 3 is a diagram modeling the photosensitive drum of the first embodiment described above. Hereinafter, with reference to FIG. 3, it will be described that in the image forming apparatus according to the first embodiment, the angular velocity of the photosensitive drum does not change even when the photosensitive drum is eccentric.

As shown in FIG. 3, the photosensitive drum 301 having a radius R is rotating around a point O while being eccentric. FIG. 3 shows the x-axis and the y-axis with the point O as the origin. When the center of gravity of the photosensitive drum 301 is at G, the eccentricity is represented by ε as the length of a straight line connecting the point O and the point G, and θ as an angle formed between the straight line and the x-axis. Hereinafter, in this specification,
Let ε be the amount of eccentricity, and the position represented by (ε, θ) be the eccentric position.

The coordinates of the transfer position T between the photosensitive drum 301 and the conveyor belt 302 are expressed as (εcos θ−R + sin θ) using the eccentric position (ε, θ). Therefore, the moving speed VTx in the x direction of T and the moving speed VTy in the y direction
Is expressed as follows. VTx = −ε · sin θ · ω (1) VTy = ε · cos θ · ω (2) where ω = dθ / dt

Using the equations (1) and (2), the velocity Vs in the direction of rotation about the point O (this direction is indicated by a straight line S) is: Vs = V · cos α−ε · sin θ · ω · cosα + ε
Cos θ · ω · sin α (3) where V indicates the moving speed of the conveyor belt 302, and α is an angle formed by a straight line S orthogonal to a straight line r connecting the transfer position T and the point O with the conveyor belt 302. .

Therefore, ω = Vs / r = (V · cos α−ε · sin θ · ω · cos α + ε · cos θ · ω · sin α) / r (4) where r ² = R ² + ε ² −2Rεcos ( (π / 2−θ) = R ² + ε ² −2 · R · ε · sin θ (5) ε / sin α = r / sin (π / 2−θ) = r / cos θ (6) = Ε · cos θ / r (7) cos α = (R−ε · sin θ) / r (8)

[0089] Equation (5), (7), by substituting (8) into equation (4), ω = {V · R- (V + ω · R) ε · sinθ + ω · ε 2} / (R 2 + ε ² −2R · ε · sin θ) (9) By transforming equation (9), ω (R ² + ε ² −2R · ε · sin θ) = VR · (V + ω · R) ε · sin θ + ω · ε ² . Since (9) ′, V = R · ω (10) is obtained.

That is, when the conveying belt 302 is driven at a constant speed V and no force is applied to the transfer position T by a pressing roller or the like, the rotational angular velocity of the photosensitive drum 301 may be constant regardless of eccentricity. Understand.

Detection of State of Image Forming Apparatus Next, the transfer position shift due to the eccentricity of the photosensitive drum, the eccentricity of the photosensitive drum, the actual drum radius of the photosensitive drum,
The detection of the state of the image forming apparatus such as the operation of the writing unit will be described.

First, detection of the transfer position when the photosensitive drum is eccentric will be described. FIG. 4 is a diagram for explaining obtaining the transfer position of the latent image written on the eccentric photosensitive drum 401. In FIG. 4,
Taking the x-axis and the y-axis with the point O representing the cross section of the rotation axis of the photosensitive drum 401 perpendicular to the paper surface as the origin, the photosensitive drum 40
It is assumed that the coordinates related to No. 1 are represented.

The radius R of the photosensitive drum shown in FIG. 4 has a radius R in a cross section orthogonal to the rotation axis, and rotates around a point O with an eccentricity represented by an eccentric position ε. Further, due to this eccentricity, the center of gravity of the photosensitive drum 401 changes so as to move on the circumference e of the circle having the radius ε.

After the latent image is written on the photosensitive drum 401, the written latent image is converted into a toner image by a developing device and is transferred to a sheet. When the photosensitive drum 401 has no eccentricity,
A latent image is written at an upper point (0, R) of the photosensitive drum 401 that intersects with the y-axis. The photosensitive drum 401 is designed to rotate by π during a predetermined time, and to transfer a toner image onto a sheet at a lower point (0, -R) crossing the y-axis.

However, the center of gravity of the photosensitive drum 401 is G
When at 2, the latent image is written at the location indicated by E. The written latent image is developed by a developing device to become a toner image. Then, when the eccentric photosensitive drum 401 rotates by Δt and the center of gravity is at G1, the photosensitive drum 401 is transferred to a sheet (not shown) at the transfer position T1. At this time, the transfer position T1 is shifted by -s (s is referred to as a shift amount) in the x direction from the transfer position (0, -R) when the photosensitive drum 401 has no eccentricity.

The shift amount s is obtained as follows. That is, the rotation angle Δt at which the eccentric photosensitive drum 401 rotates from the writing of the latent image to the transfer of the latent image is the angle G2E.
Using the angle β represented by O, it is represented as follows: Δt = π−β (11) Since sinβ = (ε / R) cosθ (12), Expression (11) is expressed as follows: {t = π−sin− ¹ } (ε / R) cosθ} (13) Since s = ε · cos (θ−β), s = ε · cos θ (ε / R) [｛(R / ε) ² −cos ² θ｝ ^1/2 + sin θ] (14) is obtained. Therefore, even when the photosensitive drum 401 is eccentric, if the maximum eccentricity ε and the angle θ (FIG. 4) formed by the maximum eccentricity at the moment when the latent image is written (exposed) are known, the latent image can be formed. The rotation angle Δt at which the photosensitive drum 401 rotates from the writing to the transfer and the shift of the transfer position in the x-axis direction can be determined.

As described above, when the transfer position shifts, the transfer position of the toner image on the conveyor belt 402 also shifts. Position shift amount d of toner image on conveyor belt
Is obtained as follows.

The toner image formed based on the latent image written on the photosensitive drum 401 is transferred after the photosensitive drum 401 rotates by Δt from the writing of the latent image. Therefore, the time τ required from the writing of the latent image to the transfer is represented by Δt / ω = τ (15), where ω is the angular velocity at which the photosensitive drum 401 rotates.

Further, there is no eccentricity, and the radius R ₀ according to the design value is obtained.
When the photosensitive drum (ideal drum) having the rotation at an angular velocity ω ₀ , the time τ ₀ required from the writing of the latent image to the transfer is represented by π / ω ₀ = τ ₀ (16). That is, the eccentric photosensitive drum 401 and the ideal drum have a difference of τ ₀ −τ in the time from writing to transfer. For this reason, the transport belt 40 of the photosensitive drum 401 has a radius that varies and is eccentric.
The deviation amount d between the transfer position on the transfer belt 2 and the transfer position of the ideal drum on the conveyor belt 402 is as follows: d = V (τ ₀ −τ) = V (π / ω ₀ −Θt / ω) = π (R ₀ − R) + Rsin ^-1 {(ε / R) cos θ} (17) When the latent image is formed by generating image data as an ideal drum, if the photosensitive drum has an eccentricity or a variation in diameter, the image is transferred to a position shifted by d, causing a color shift. . Therefore, if an image to be transferred to a position shifted by d is generated in advance to form a latent image, an image corresponding to the transferred position can be formed, so that color shift does not occur.

By operating the writing unit in consideration of the deviation amount d obtained as described above, the image forming apparatus according to the first embodiment has the eccentricity of the photosensitive drum.
Alternatively, even when the radius of the photosensitive drum is different from the radius of the ideal drum, the toner image can be transferred to the same position as the toner image transferred by the ideal drum.

In order to obtain the displacement d, it is necessary to detect the actual rotation radius Δt of the drum, which represents the radius R of the photosensitive drum and the eccentric position (ε, θ). Next, the configuration of the image forming apparatus that detects the radius R, the eccentric position (ε, θ), and the rotation angle Δt will be described.

FIG. 5 is a diagram for explaining a configuration in which the image forming apparatus of the first embodiment detects the photoconductor drum radius R, the eccentric position (ε, θ), and the rotation angle Δt of its own device. Note that the same components as those shown in FIG. 1 among those shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be partially omitted.

The configuration shown is a photosensitive drum C101,
The photoconductor drum M102, the photoconductor drum Y103, the photoconductor drum K104, and the transport belt 115 are provided.
Further, the photosensitive drum C101, the photosensitive drum M102,
The photoconductor drum Y103 and the photoconductor drum K104 are respectively provided with rotation angle detection encoders 501 and 5 for detecting a rotation angle.
02, 503, 504 and an eccentricity detector 5 for detecting eccentricity
21, 522, 523, and 524.

On the other hand, the transport belt 115 has a paper passage area 512 through which the paper is transported and passed.
A paper passage detector 508 for detecting the passage of the paper is provided inside the paper passage area 512. Outside the paper passage area 512, a timing mark 510 for detecting the amount of movement of the conveyor belt 115 and a reference mark 511 indicating the tip of the conveyor belt 115 are formed. Further, a timing mark 5 is provided above the transport belt 115.
10, a linear encoder 507 for generating a pulse each time a timing mark is detected, and a reference mark 5
A tip position detector 509 for detecting the position of the reference mark 11 and a reference position error detector 506 for detecting the amount of positional deviation between the toner image and the reference mark 511, which will be described later, are provided.

Rotation Angle Detecting Encoder 5 of First Embodiment
Reference numerals 01, 502, 503, and 504 denote encoders that can detect the absolute value of the rotation angle of the photoconductor drum, and generate a pulse each time the photoconductor drum rotates by a predetermined angle. Rotation angle detection encoders 501, 502, 503, 504
Functions as a writing start position detecting means for detecting a position where writing to each photosensitive drum is started.

Also, the eccentricity detector 521 of the first embodiment,
Reference numerals 522, 523, and 524 denote light-emitting elements that irradiate a light beam to the peripheral surface of each photosensitive drum, light-receiving elements that receive light beams reflected by the peripheral surface of the photosensitive drum, and eccentricity of the photosensitive drum peripheral surface. An optical system that can detect a change in the amount of light received by a light receiving element (for example, a two-division photodiode) when displaced. As such an eccentricity detector,
For example, it is conceivable to employ a focus error detection method used in the field of optical disks.

When the eccentricity detector is configured to detect eccentricity by the focus error detection method, a photocurrent that changes according to the distance between the eccentricity detector and the peripheral surface of the photosensitive drum flows to the light receiving element. When the photocurrent is extracted from the light receiving element as an electric signal, a waveform curve that changes with a constant cycle and amplitude is obtained. The eccentric position (ε, θ) is obtained from the obtained amplitude and cycle of the waveform curve.

FIG. 6 shows a reference mark 511 and a photosensitive drum C101, a photosensitive drum M102, a photosensitive drum Y103, and a photosensitive drum K1 based on the reference mark 511.
FIG. 4 is a diagram illustrating toner images 601C, 601M, 601Y, and 601K serving as reference toner images formed on the conveyor belt 115. A writing unit (not shown) writes a latent image (reference latent image) on the photosensitive drum C101 assuming that the photosensitive drum C101 is an ideal drum. The reference latent image is developed by a developing device (not shown), and a toner image 60
1C, and is transferred to the conveyor belt 115. The timing of writing and transferring the reference latent image is performed at a timing at which the toner image 601C is transferred so as to coincide with the reference mark 511.

Similarly, the writing unit of the photosensitive drum M102, the writing unit of the photosensitive drum Y103, and the writing unit of the photosensitive drum K104 are similarly transferred to the toner image 601M,
The transfer belt 11 transfers the toner image 601Y and the toner image 601K.
Transfer onto 5 As a result, as shown in FIG. 6, it is possible to form a pattern in which the difference between the ideal writing and transfer timing of each photoconductor drum and the actual writing and transfer timing is recognized. At this time, in the first embodiment, the pattern shown in FIG. 6 is formed directly on the transport belt 115 without transporting the sheet.

FIG. 7 is a block diagram for explaining a configuration for controlling the configuration shown in FIG. The configuration shown is
The reference position error detector 506, the linear encoder 507, and the rotation angle detection encoders 501 and 50 described in FIG.
2, 503, 504 and eccentricity detectors 521, 522, 5
23, 524, reference position error detector 506, linear encoder 507, rotation angle detection encoders 501, 50
2, 503, 504, eccentricity detectors 521, 522, 52
3 and 524, the detected information is input, the radius R and the eccentric position (ε, θ) are calculated based on the information, and the writing unit control units 702, 703,
And a control unit 701 for controlling 704 and 705.

In the configuration shown in FIG.
Are eccentricity detectors 521, 522, 523, and 524, a reference position error detector 506, a linear encoder 507, and rotation angle detection encoders 501, 502, 503, and 504.
Functions as timing adjustment means for adjusting the generation timing of the data to be written to each photosensitive drum based on the actual measurement value.

A memory 703 for storing the calculated values is connected to the control unit 701. Further, an operation signal for operating the image forming apparatus is input. Four write unit controllers 702, 703, 704, 705
Are provided corresponding to the writing units provided on each of the photosensitive drum C101, the photosensitive drum M102, the photosensitive drum Y103, and the photosensitive drum K104.

The configuration shown in FIGS. 5 and 7 operates as follows to detect the radius R, the eccentric position (ε, θ), and the rotation angle Δt. That is, when image formation starts, a control device (not shown) that controls the entire image forming apparatus rotates the drive roller 106 to move the transport belt 115. At this time, the linear encoder 507 detects the timing mark 510 of the transport belt 115. The movement amount of the conveyor belt 115 is detected based on this signal, and the conveyor belt 115 is detected.
Is moved by the circumference L (2πR ₀ ) of the ideal drum.

On the other hand, the rotation angle detecting encoders 501, 5
02, 503, and 504 are photosensitive drums C10, respectively.
1. The rotation angles of the photosensitive drums M102, Y103, and K104 are input to the control unit 701. The control unit 701 obtains the actual radius R of each photoconductor drum from the rotation angle θi of each photoconductor drum when the transport belt 115 moves by L as R = L / θi (18).

With the above operation, the photosensitive drum C10
1. The actual radius R of the photosensitive drum M102, the photosensitive drum Y103, and the photosensitive drum K104 is calculated. The calculated radius R is output from the control unit 701 to the memory 703 and stored. Also, the rotation angle detection encoder 50
1, 502, 503, and 504 are the photosensitive drum C10
1. The rotation angles of the photosensitive drums M102, Y103, and K104 are input to the control unit 701. Then, the eccentricity detectors 521, 522, 523, 52
4 is a photosensitive drum C101, a photosensitive drum M102,
Information regarding the eccentricity of the photosensitive drums Y103 and K104 is input to the control unit 701 as eccentricity signals. The control unit 701 can obtain information on the eccentric position (ε, θ) from the information on the rotation angle of the photosensitive drum and the eccentric signal.

Adjustment of Image Forming Conditions According to State of Image Forming Apparatus Next, adjustment of image forming conditions in the image forming apparatus according to the calculated radius R, (ε, θ) will be described.
Here, θ is rotation angle information corresponding to the maximum amount of eccentricity ε at the moment when the latent image is formed. The control unit 701 substitutes the calculated R and ε into the equation (17), and calculates a shift amount d during one rotation of each photosensitive drum (θ = 0 to 2π). The calculated shift amount d of the transfer position on the sheet is
The data is stored as a reference table in the memory 703. The control unit 701 includes a rotation angle detection encoder 501,
The writing unit control units 702, 703, 704, and 705 are controlled with reference to the shift amount d corresponding to the rotation angle according to the rotation angle input from 502, 503, and 504.

Writing unit control units 702, 703, 7
The control of steps 04 and 705 adjusts the data writing timing of the latent image on each photosensitive drum according to the deviation amount d, and conveys the toner image irrespective of the eccentricity of each photosensitive drum or variation in the radius of the photosensitive drum. The transfer is performed at a fixed position on the belt 115. As a result, the toner images of the cyan, magenta, yellow, and black colors transferred on the respective photosensitive drums are misaligned on the paper regardless of the eccentricity of the respective photosensitive drums and the eccentricity due to the variation in the radius of the photosensitive drums. It is transferred without being superimposed.

Further, in the configuration shown in FIG. 7, the reference position error detector 506 uses the reference mark 511, the toner image 601C, the toner image 601M, and the toner image 601 shown in FIG.
Y, the amount of deviation from the toner image 601K is detected. The detected shift amount is input to the control unit 701. The control unit 701
When the toner image 601C (601M, 601Y, 601K) is formed, if the shift amount d is corrected and formed, the writing unit may adjust the writing timing of the writing unit according to the input shift amount. The controller 702, 703, 704, 705 is controlled.

Further, the toner image 601C (601M, 601Y,
When forming (K), the shift amount d may be corrected by an arithmetic process based on the shift amount detected by the reference position error detector 506, and control may be performed so as to correct the variation in the installation position of each photoconductor drum. By this control, the image forming apparatus according to the first embodiment can also cancel the shift of the transfer position even when the installation positions of the respective photosensitive drums vary.

FIG. 8 is a diagram for explaining an image forming method performed by the image forming apparatus according to the first embodiment.
6 is a flowchart illustrating detection of the state of the image forming apparatus and adjustment of the image forming conditions. The processing of the illustrated flowchart starts when the control unit 701 receives an instruction for latent image formation control by an operation signal (step S801), and while the control unit 701 does not receive the instruction for latent image formation control (step S801: No), stand by.

When the control section 701 starts processing, the linear encoder 507 detects the amount of movement of the transport belt 115 by the linear encoder 507 while the transport belt is being driven by the control of another control section (not shown). Is calculated (step S802). Also, the eccentricity detector (521, 522, 523, 524) and the rotation angle detecting encoders 501, 502, 503, 504 detect the eccentric position (ε, θ) (step S803), and step S803.
The shift amount d is calculated together with the radius R obtained in 802.
At this time, as the shift amount d, all possible values when θ in Expression (17) changes from 0 to 2π are calculated. The calculated shift amount d is stored in the memory 703 as a reference table.
(Step S804).

Further, the control unit 701 controls the reference mark 51
1 and toner images 601C, 601M, 601Y, 601K
Is detected (step S805). And
The shift amount d corresponding to the rotation angle of each photosensitive drum at the moment when the latent image is formed is read out (step S806), and writing is performed in consideration of both the shift amount d and the shift amount between the reference mark 511 and the toner image. Unit control units 702, 703, 70
4 and 705 (Step S)
807). The control signal generated in step S807 is
Write unit control units 702, 703, 704, 705
(Step S808).

Next, the control section 701 determines whether or not the formation of the latent image has been completed (step S809). Step S
If it is determined in step 809 that the latent image formation has not been completed (step S809: No), the process returns to step S806 again to read out the deviation amount d, generate a control signal, and generate a control signal to write unit control unit. 702, 703, 704,
705.

On the other hand, if it is determined in step S809 that the image formation has been completed (step S8).
09: Yes), it is determined whether or not there is a latent image on the next page (step S810). If the result of this determination is that there is no latent image formation for the next page (step S810: N
o), the process ends. The shift amount d is, for example,
The setting is reset when the mechanical state of the image forming apparatus changes due to maintenance or mechanical adjustment of the image forming apparatus, or reset periodically at predetermined intervals. If the result of determination in step S810 is that there is formation of a latent image on the next page (step S810: Y
es) The process proceeds to step S811.

Next, it is determined whether or not an instruction to form a latent image has been issued (step S811). If an instruction to form a latent image has been received (step S811: Yes), d is read from the memory 703, and the writing unit controller 7 is read.
02, 703, 704, and 705 are controlled. In addition, while the instruction to form a latent image is not issued, the control unit 701 waits in preparation for the instruction (step S811: N
o).

The image forming method described above is realized by executing a prepared program by a controller (not shown). Alternatively, the program is recorded on a computer-readable recording medium such as a hard disk, a floppy (registered trademark) disk, a CD-ROM, an MO, and a DVD, read from the recording medium by the computer, and transferred to the controller. It may be performed by doing. Further, this program can be distributed via the recording medium and as a transmission medium via a network such as the Internet.

The present invention relates to the first embodiment described above.
However, the present invention is not limited to this. For example, in the image forming apparatus of the present invention, instead of the encoder for detecting the rotation angle, a pulse generator (a reference position for detecting a reference position of the rotation angle of the photoconductor drum) that emits one pulse each time the photoconductor drum makes one rotation. The rotation angle of the photosensitive drum can also be detected by the detecting means). When the rotation angle is detected using a pulse generator, the pulses generated by the linear encoder 507 are counted during the pulse generation cycle of the pulse generator (period of rotation of the photosensitive drum), and the linear encoder 507 outputs one pulse. The rotation angle at which the photosensitive drum rotates during the occurrence of is detected.

When the radius R of the photosensitive drum is obtained by using such a pulse generator, the linear encoder 507 detects the moving amount (Lb) of the conveyor belt 115 when the photosensitive drum makes one rotation. I do. Then, the radius R of the photosensitive drum may be calculated as R = Lb / 2π (19).

The control unit 70 of the image forming apparatus of the present invention
1 is to provide a rotation angle detecting encoder at any one position of a photoconductor drum or a roller shaft holding a conveyance belt, and to a photoconductor drum not provided with the rotation angle detection encoder, the pulse generation The deviation amount d of the image with respect to the sheet on the conveyance belt 115 of the photosensitive drum can be detected (derived) by using a device.

Further, the radius R and the eccentric position (ε, θ) of the photosensitive drum are measured at the factory before shipping the image forming apparatus, and are stored in a flash memory provided in the image forming apparatus. Can also.

Next, embodiments 2, 3, and 4 of the image forming apparatus of the present invention will be described. Embodiment 2,
The image forming apparatuses of the third and fourth embodiments are different from the image forming apparatuses of the first embodiment in that the conveying belt is conveyed every time the conveying belt moves a predetermined distance in order to further reduce the slip between the photosensitive drum and the conveying belt. The motor further includes a motor that rotates the transport belt drive motor in synchronization with a pulse generated by a rotation angle detection encoder attached to the drive roller that holds the belt. The first embodiment is established when there is no slip between the photosensitive drum and the belt or between the photosensitive drum and the paper.

Embodiments 2, 3, and 4 are based on the following concept. That is, it is necessary to take into consideration that when the frictional force between the photosensitive drum and the transport belt, or between the photosensitive drum and the paper, or between the paper and the transport belt is small, it is easy to slip. That is, it is necessary to reduce the control error of the load fluctuation correction control system which controls the photosensitive drum so as to cancel the load fluctuation by generating a force against the load fluctuation applied to each photosensitive drum. That is, if the force in the belt moving direction applied to the transport belt or the sheet caused by the control error becomes larger than the frictional force, slip occurs. The second, third, and fourth embodiments are made to deal with these matters.

In the second embodiment, a load fluctuation correction control system for detecting reverse power proportional to the rotation speed of the load fluctuation correction motor and comparing it with a reference speed signal for determining an appropriate rotation speed is controlled. Make up. In the third embodiment,
Further, in order to improve the accuracy of the load fluctuation correction control system compared to the second embodiment, the phase difference between a pulse generated once per rotation of the photosensitive drum and a reference pulse having an appropriate pulse interval for determining an appropriate rotation speed is calculated. A load fluctuation correction control system that performs comparison and control is configured. Further, the fourth embodiment provides a more accurate and stable load fluctuation correction control system in combination with the second or third embodiment based on the following principle.

The error of the load fluctuation correction control system becomes a load on the transport belt drive system. Therefore, by observing the current waveform flowing through the transport belt drive motor, it is determined whether the correction of the load variation motor is excessive, insufficient, or appropriate, and the reference signal (amplitude, pulse frequency, etc.) of the load correction drive motor control system is determined. Is corrected.

In other words, a control error corresponding to various load fluctuations on a certain photosensitive drum is transmitted as a load fluctuation of the transport belt drive motor. The transport belt drive motor is
In order to move so as to rotate at a constant speed against the load fluctuation, a drive current for that flows to the transport belt drive motor. Therefore, if this is detected and fed back to the load fluctuation correction motor control system, the load fluctuation for the overall drive control can be further reduced.

If a load greater than the friction between the photosensitive drum and the conveyor belt is applied without the correction being successful, a slip phenomenon occurs. Therefore, the load fluctuation correction motor control system controls the current applied to the system of the transport belt drive motor current component so as not to be larger than a certain value. However, it is not known where the drive current flowing through the transport belt drive motor is caused by an error in the load fluctuation correction control system. Therefore, a sine wave for identification of the drive current of the load fluctuation correction motor (superimposed sine wave for identification) is superimposed. That is, the load fluctuation correction current is modulated.

If this frequency is higher than the control band of the overall drive motor, the control of the overall drive motor does not work, and the speed of the transport belt fluctuates at this frequency. Within the control band of the overall drive motor, the control system works to correct this frequency variation, and current flows through the overall drive motor. If the overall drive motor control system has a sufficient gain, the effect on the image due to the fluctuation of the transport belt due to this error can be ignored. By detecting the previously determined frequency component of the current flowing through the overall drive motor, it is possible to detect the situation in which the load fluctuation correction motor is being controlled.

The speed of the photosensitive drum fluctuates due to the current signal of the superimposed sine wave for identification, and the fluctuation must not affect the image formation. It is sufficient that the driving frequency of the superimposed sine wave for identification can be increased so as not to affect the fluctuation in the speed of the photosensitive drum, but it is usually quite difficult. In other words, the frequency of the superimposed sine wave for identification must be selected within the entire drive motor control band. Accordingly, the modulation degree of the drive current is determined so that the fluctuation of the photosensitive drum speed due to the drive current does not affect the image. In other words, even in the worst case, the modulation factor is selected so that the speed fluctuation of the photosensitive drum does not affect the image. If the modulation degree is determined, it is possible to measure what load is applied to the entire motor drive control system as a whole.

If the current frequency of the superimposed sine wave for identification of each photosensitive drum can be changed, it is possible to simultaneously detect what load is acting on the entire motor drive control system as a whole. In this case, the control band of the entire drive system needs to be considerably wide. Therefore, when this band cannot be obtained, it may be detected by the time division method. In addition, it is effective to detect at a timing other than the time of image formation instead of always providing feedback when the friction between the photosensitive drum and the conveyance belt is not large, that is, when the allowable control error is small. is there. For example, it may be executed before image formation or when starting up the apparatus. If a timing other than the image forming mode is selected, the rotation speed of the photosensitive drum may vary.

In order to ensure that the above-described operations can be performed before image formation, the amplitude of the reference signal of the load fluctuation correction control system (or the gain for obtaining an appropriate amplitude), Alternatively, the reference pulse frequency needs to be set in advance with high accuracy. That is, this is to prevent the above-mentioned slip from occurring at the time of image formation. Therefore, first, the reference signal of the load fluctuation correction system is fixed, and the drive including the entire drive motor is performed. The reference input of the load fluctuation correction system (reference speed signal of the load fluctuation correction system) has a large error because it is not corrected. For this reason, the gain of the load fluctuation correction control system is reduced in advance. At this time, the load around the photosensitive drum is small because the image forming process is not operating, so that it is possible to select a condition that allows sufficient driving. And
As described above, in order to sequentially obtain the amplitude of the reference signal input of each load fluctuation correction system (or a gain for obtaining an appropriate magnitude of the amplitude) or the reference pulse frequency, To correct the reference input. When those corrections have been completed for the four load fluctuation correction systems, the image forming apparatus is ready for image formation.

FIG. 9 shows a configuration for realizing the above idea.
Shown below. FIG. 9 is a diagram for explaining main parts of the image forming apparatuses according to the second, third, and fourth embodiments. The illustrated image forming apparatus is a tandem-type image forming apparatus including a photosensitive drum C901, a photosensitive drum M902, a photosensitive drum Y903, and a photosensitive drum K904, similarly to the image forming apparatus of the first embodiment. Further, the image forming apparatus includes a conveyance belt 915, a roller 905, and a conveyance belt 9
15 is provided with a conveyance belt driving roller 906 for driving the roller 15, a tension roller 914, and rollers 911, 912, and 913. A tip position detector 909 is provided above the conveyor belt 915, and detects a reference mark (not shown) formed on the conveyor belt 915. This is used when a reference mark as shown in FIG. 6 is detected to form a reference latent image.

The image forming apparatuses according to the second, third, and fourth embodiments also include an image reading section such as a scanner, a sheet feeding section including a sheet feeding cassette, a fixing section for fixing a toner image on a sheet, a sheet discharging section, It has a corona charger. Then, the photosensitive drum C901, the photosensitive drum M902, the photosensitive drum Y
903, each of the photosensitive drums K904 includes a writing unit that scans a surface with a laser beam to write a latent image, a developer that supplies toner to the latent image to form a toner image, a cleaner, a charger, and the like. I have. Since the above configuration is also a known configuration, illustration and description are omitted.

The developing device provided on the photosensitive drum C901 supplies cyan toner, the developing device provided on the photosensitive drum M902 supplies magenta toner, and the developing device provided on the photosensitive drum Y903. The provided developing device supplies the yellow toner,
The developing device provided on the photosensitive drum K904 supplies black toner.

In the image forming apparatus shown in FIG. 9, the photosensitive drum C901, the photosensitive drum M902, the photosensitive drum Y
903, a rotation angle reference position detector 931, 932, 933 for detecting the reference position of the rotation angle of the photosensitive drum K904;
934. The conveyor belt driving roller 906 for driving the conveyor belt is provided with a rotation angle detection encoder 9.
08. Rotation angle reference position detectors 931 and 93
2, 933 and 934, for example, a pulse generator for generating a pulse each time the photosensitive drum makes one rotation, and a rotation angle detection encoder 908, for example, an encoder for generating a number of pulses corresponding to the moving amount of the conveyor belt Is used.

A photosensitive drum C901, a photosensitive drum M902, a photosensitive drum Y903, a photosensitive drum K9
04 are load fluctuation correction motors 921 and 92, respectively.
2, 923, and 924, and the transport belt driving roller 906 includes a motor 907 directly connected to the rotation shaft.

The motor 907 is a motor for rotating the conveyor belt 915. That is, when the motor 907 rotates, the transport belt driving roller 906 rotates, and the transport belt 915 that contacts the transport belt driving roller 906 is rotated.
To move. The rollers 905, 911, 912, 913 and the tension roller 914 rotate following the rotation of the conveyor belt 915. Also, the load fluctuation correction motor 92
1, 922, 923, and 924 are photosensitive drums C90.
1. The configuration is such that a change in load applied to the photosensitive drum M902, the photosensitive drum Y903, and the photosensitive drum K904 is detected, and a change in load is suppressed by causing the motor torque to oppose the detected change.

The load fluctuation correcting motors 921 and 92
The load for suppressing the fluctuation in 2, 923 and 924 refers to a load generated by a cleaner or the like on the peripheral surface of the photosensitive drum. Such loads can fluctuate periodically. In addition, the control of the image forming apparatus by the rotation angle detection encoder 908 and the motor 907 and the load fluctuation correction motors 921 and 92
The operations of 2, 923 and 924 will be described later in detail.

As shown in FIG. 10, the load fluctuation correction motor (load fluctuation correction motor 924 in FIG. 10) is provided in the area where writing is performed on the photosensitive drum (photosensitive drum K904 in FIG. 10). A relatively small roller 100 outside
1 can be attached. By attaching the load fluctuation correction motor 924 in this manner, the motor efficiency is increased, the power consumption can be reduced, and a small motor can be used as compared with the case where the motor is directly connected to the photosensitive drum. It is possible to suppress an increase in the size of the image forming apparatuses of the third, fourth, and fourth aspects.

In the image forming apparatuses according to the second, third, and fourth embodiments, the pulse generated by the rotation angle detecting encoder 908 is detected, and the measured value of the pulse and the rotation angle reference position detectors 931, 932, The rotation amounts of the photosensitive drums 901, 902, 903, and 904 detected by 933 and 934 are compared. From this comparison, the second embodiment,
In the image forming apparatuses of Nos. 3 and 4, the rotation angle of the photosensitive drum rotating while the conveyor belt driving roller 906 makes one rotation can be detected. Alternatively, the number of pulses generated by the rotation angle detection encoder 908 during one rotation of the photosensitive drum can be detected.

Further, in the image forming apparatus in which the conveying belt is moved by the driving roller as in the image forming apparatuses of the second, third and fourth embodiments, the conveying belt driving roller 906 which rotates while the photosensitive drum makes one rotation is used. The amount of rotation is stored in advance. Then, the stored rotation amount of the conveyor belt driving roller 906 and the detected conveyor belt driving roller 906 are detected.
Are compared with each other, and when the difference between the two exceeds an allowable range, it is determined that the image forming apparatus is abnormal.

FIG. 11 shows an encoder 908 for detecting a rotation angle.
FIG. 3 is a block diagram for describing control of the image forming apparatus by a motor and a motor 907. The configuration shown in FIG. 11 includes a conveyance belt driving roller 906, a motor 907 for rotating the conveyance belt driving roller 906, a rotation angle detection encoder 908 for detecting a rotation angle of the conveyance belt driving roller 906, and a rotation angle detection encoder 908. Control circuit 11 for controlling motor 907 based on a signal detected by encoder 908
00, a power amplifier 1104, and a phase compensator 1105
, An fV converter 1106, and an encoder pulse detector 1107. Further, the control circuit 1100 includes:
Phase comparator 1101, charge pump 1102, LPF
(Low Pass Filter) 1103.

The frequency fr of the pulse output from the rotation angle detecting encoder 908 when the speed of the transport belt reaches the target speed V is based on the following equation. That is, the target speed V of the conveyor belt, and the radius of the conveyor belt drive roller 906 and Rr, the rotation speed omega _r of the entire drive motor, is expressed as follows. ω _r = V / Rr (20) Further, assuming that the number of pulses output by the encoder during one rotation of the transport belt driving roller 906 is Nr, the frequency fr of the pulse output by the encoder is: fr = Nr · ω _r / (2π) = Nr · V / (2πRr) (21) The control unit generates a signal S1 equal to the frequency fr and inputs the signal S1 to the phase comparator 1101.

The phase comparator 1101 receives the pulse signal S4 based on the pulse actually output from the rotation angle detection encoder 908, compares the pulse signal S4 with the reference pulse S1, and calculates the difference between the two phases. The calculated value is stored in the charge pump 11
02, passes through the LPF 1103, is converted into a voltage signal expressed in analog, and is further input to the power amplifier 1104. The power amplifier 1104 outputs a control signal to the motor 907 based on the phase difference between the input signals S1 and S4, and controls the motor 907 so that the transport belt 915 moves at the target speed V. As a result, the motor 907
Rotates at a constant speed at an angular speed obtained when the conveyor belt 915 moves at the target speed V. The above process is a known process called a PLL (Phase Locked Loop).

The pulse generated by the rotation angle detection encoder 908 is output to the fV converter 1106 via the encoder pulse detector 1107. fV converter 1
106 converts the pulse into a voltage signal and generates a voltage signal S3 proportional to the angular velocity of the transport belt driving roller 906. The voltage signal S3 is fed back to the power amplifier 1104 through the phase compensator 1105 to improve the speed control characteristics of the transport belt driving roller 906.

Further, since the voltage signal S3 is proportional to the angular velocity of the transport belt driving roller 906, the voltage signal S3 is output to another configuration as a signal indicating the rotational speed of the transport belt driving roller 906, and the voltage signal S3 is composed of a photosensitive drum. Used for speed control.

The transport belt drive roller 9
06 or a change (magnitude, timing) of the load applied to the conveyor belt 915 is obtained, and this load change is externally applied as a feedforward signal S2. Such feedforward control can improve the speed control characteristics of the conveyor belt system.

It is to be noted that the timing and the magnitude of the change in the load applied to the photosensitive drum of the electrophotographic apparatus (printer or copier), the driving roller for the conveyor belt, or the conveyor belt are known in advance. Therefore, the above-described feedforward control can be performed.
In the embodiment of FIG. 9, the encoder 908 for detecting the rotation angle and the motor 907 which are directly connected to the shaft of the conveyor belt drive roller 906 are used, but these encoders or motors may be connected via a gear.

(Embodiment 2) Next, Embodiment 2 of the image forming apparatus will be described. FIG. 12 is a block diagram for explaining a configuration for controlling the load fluctuation correction motor. The illustrated configuration is a drum C load fluctuation correction control system 1200 that corrects the load fluctuation of the photosensitive drum C901.
A feed forward signal generator 1210; a drum M load fluctuation correction control system 1206 for correcting a load fluctuation of the photosensitive drum M902; a drum Y load fluctuation correction control system 1207 for correcting a load fluctuation of the photosensitive drum Y903; A drum BK load fluctuation correction control system 1209 for correcting a load fluctuation of the drum K904 is provided.

The drum C load fluctuation correction control system 120
0 is the current source type power amplifier 1201 and the phase compensator 12
02, load fluctuation correction motor 921, back electromotive force detector 1
203, a comparator 1205 used for detecting the back electromotive force.

In the above configuration, the load fluctuation of the photosensitive drum is canceled by the torque of the load fluctuation correcting motor 921, and the influence of the load fluctuation of the photosensitive drum on other photosensitive drums via the conveyor belt is minimized. It is to suppress.

Feed forward signal generator 1210
Are known photosensitive drums C901 and M90.
2. A signal for generating a torque for canceling the variation (magnitude, timing) of the load applied to the photosensitive drum Y 903 and the photosensitive drum K 904 is transmitted to a control system corresponding thereto, that is, a drum C load variation correction control system 1200; A feedforward signal is input to the M load fluctuation correction control system 1206, the drum Y load fluctuation correction control system 1207, and the drum BK load fluctuation correction control system 1209.

The drum C load fluctuation correction control system 120
0, a drum M load fluctuation correction control system 1206, a drum Y load fluctuation correction control system 1207, and a drum BK load fluctuation correction control system 1209 each receive a voltage signal S3. The signal S3 is a signal for determining the rotation speed of the load fluctuation correction motor. However, the signal S3 is converted into a value such that the conveyance belt 915 and the photosensitive drum rotate at a speed at which the conveyance belt 915 and the photosensitive drum move together, and is used as a reference signal for determining the rotation of the motor.

Further, the reference signal to the load variation correction control system for each photosensitive drum may be a reference signal for determining the rotation of the motor by performing correction in consideration of variation in the radius of the photosensitive drum. Further, the drum C load fluctuation correction control system 1200 in FIG. 12 detects the back electromotive force generated in proportion to the rotation speed of the load fluctuation correction motor 921, and compares the detected voltage with the voltage signal S3 to control the speed. In the second embodiment, other load fluctuation correction control systems have the same circuit configuration. The load fluctuation correction control system controls the motor to rotate even if there is a load fluctuation at a speed determined by a reference signal that determines the rotation of the load fluctuation correction motor. As a result, the amount of transmission of the load fluctuation to the other drive system is reduced, and the occurrence of slip between the photosensitive drum and the conveyance belt or between sheets can be reduced.

With the above operation, the load fluctuation correction motors 921, 922, 923, and 924 are moved by the transport belt 915.
Is controlled according to the rotational angular velocity of the motor 907 for driving the motor. For this reason, the image forming apparatus according to the second embodiment can be configured so that slippage with the photosensitive drum (only one of the photosensitive drum and the transport belt 915 moves) does not easily occur even at the time of startup. .
The back electromotive force generated in the load fluctuation correction motor 921 can be detected by subtracting the internal resistance from the voltage applied to the terminal. Also, a current source type power amplifier 1201 is used as a power amplifier, and a phase compensator 1202 is used.
Is provided in order to enhance the control characteristics of the configuration shown in FIG.

Further, as another configuration example, the signal for determining the rotational angular velocity of the load variation correction motor may be generated by a controller (not shown). Further, in the second embodiment, other control modes such as start and stop are not described, but these can be realized by a conventional technique.

As described above, according to the image forming apparatus of the second embodiment, the driving system including the photosensitive drum and the conveyor belt 915 is speed-controlled by the motor 907, and the conveyor belt driving roller 906 rotated by the motor 907. The fluctuation of the load applied to the other photosensitive drum and the conveyor belt 915 that rotates following the rotation can be corrected by individual control systems.

Embodiment 3 Next, Embodiment 3 of the image forming apparatus will be described. The third embodiment is a further improvement of the second embodiment. In other words, taking advantage of the fact that the photoconductor drum moves at a constant rotational angular speed when the conveyor belt moves at a constant speed, the rotation speed of the photoconductor drum can be adjusted more accurately so that slip does not occur between the photoconductor drum and the conveyor belt or paper. It provides a way to set it. FIGS. 13 and 14 are block diagrams for explaining a configuration for controlling the load fluctuation correction motors 921, 922, 923, and 924. The configuration shown in FIG. 13 is a drum load fluctuation correction control unit that detects the rotation state of the photoconductor drum and overcomes the load fluctuation applied to the photoconductor drum according to the state to control the photoconductor drum at a constant angular velocity. . The drum load fluctuation correction control unit controls the load fluctuation correction motor at a constant speed, and acts to cancel the load fluctuation applied to the photosensitive drum by the torque of the load fluctuation correction motor. Since the influence of the load fluctuation on other photosensitive drums and the like is suppressed, and the load fluctuation on the transport belt or the paper is suppressed, slippage can be prevented. In addition, the configuration shown in FIG. 14 generates the clock frequency fd which is a reference for the processing of the configuration shown in FIG.
The generation unit.

The fd generator shown in FIG. 14 comprises a frequency synthesizer 1301 and a k (N + P) counter 1302
And the PLL processing unit 1303 (k · No counter 1305)
And phase comparator, charge pump, loop filter, V
And a controller 1306 for controlling the above configuration.

The frequency synthesizer 1301 outputs a pulse signal from an oscillator (not shown) oscillating at a pulse oscillation frequency equal to the frequency fr of the pulse output from the rotation angle detection encoder 908 when the conveyor belt 915 is moving at the speed V. receive. Then, based on the frequency fr, a pulse frequency fdo when the rotation angle reference position detector of the ideal photosensitive drum outputs the pulse is generated. Then, the reference clock frequency fd of the load fluctuation correction control system of FIG. 13 is generated by the PLL processing unit 1303 and the k (N + P) counter 1302. The frequencies fdo and fd may be pulse frequencies according to the following relational expression.

When the motor 907 is driven to move the conveyor belt at the moving speed V, the photosensitive drum rotates. At this time, the rotational angular velocity ω of the photosensitive drum is expressed as ω = V / R. When each photoconductor drum is rotated at an angular velocity of each ω according to this formula, no slip occurs in any photoconductor drum. In the case of the ideal photosensitive drum diameter Ro, the encoder output pulse number No when the photosensitive drum makes one rotation is as follows: No = Ro · Nr / Rr (22) If Ro / Rr is mechanically designed to be a natural number, more accurate control becomes easier.

In the present embodiment, when measuring the actual radius of the photosensitive drum, the number of pulses output by the rotation angle detecting encoder 908 when the photosensitive drum makes one rotation is counted. The number of pulses detected during one rotation of the photosensitive drum is N, and the phase indicating the interval between pulses is 2π.
If P (where 0 <P <1), the rotation angle detection encoder 908 makes N +
The pulse of P is output. Therefore, the actual radius R of the photosensitive drum is expressed as follows: R = Rr (N + P) / Nr (23)

In order for the conveying belt speed V and the photosensitive drum to move as a unit, the rotational angular speed ω of the photosensitive drum may be determined by the following equation. ω = V / R = V · Nr / {Rr (N + P)} ... (24) rotational speed omega _o of the photosensitive drum of the ideal shape ω _o = V / R _o
It is. From the above, ω = {No / (N + P)} ω ₀ (24) ′ holds.

At this time, the output pulse frequency fd of the rotation angle reference position detector 931 is fd = ω / (2π).
The output pulse frequency fdo of the rotation angle reference position detector of the ideal shape photosensitive drum is fdo = ω ₀ / (2π) Therefore, fd = {No / (N + P)} fdo (25) The relationship between fr and fdo is fr = Nr · V / (2πRr) = (Nr · Ro / Rr) fdo (26) fdo = {Rr / (Nr · Ro)} fr (27)

The frequency synthesizer 1301 uses the equation (27).
The frequency fdo output after performing the frequency conversion corresponding to
Is input to the k (N + P) counter 1302 via the PLL processing unit 1303. The controller 1306 is a PL
The L processing unit 1303 controls the k (N + P) counter 1302 to change the frequency fdo to the frequency fdo corresponding to the equation (25).
Calculate d. Note that k shown in the figure is a natural number,
It is determined according to the detection accuracy of the rotation angle detection encoder 908. For example, the phase detection resolution of the rotation angle detection encoder 908 is 0.2 × 2π (（of the pulse period).
In the case of (period), an appropriate number of 5 or more is selected as k.

The PLL processing unit 1303 sets fdo to k · N
In this configuration, the frequency is multiplied by o · fdo. The k (N + P) counter 1302 is a presettable counter whose count value can be set, and calculates fd by dividing k · No · fdo. Note that a number rounded to a natural number is used for kP. The frequency fd calculated as described above is output to the drum load fluctuation correction control unit shown in FIG.

The drum load fluctuation correction control unit shown in FIG. 13 includes a phase comparator 1307, a charge pump 1208, a loop filter 1309, a controller 1306, and a DA.
It includes a converter 1407, a phase compensator 1204, a current source type power amplifier 1201, and a load fluctuation correction motor 921. The drum load variation correction control unit is provided for each of the plurality of photosensitive drums provided in the image forming apparatus. FIG. 13 shows the photosensitive drum C901.

The frequency fd generated by the fd corrector is input to the phase comparator 1307 of the drum load fluctuation correction controller. Further, the pulse signal from the rotation angle reference position detector 931 of the photosensitive drum corresponding to the drum load variation correction control unit is input to the phase comparator 1307. The drum load fluctuation correction control unit compares the frequency and phase of the input pulse signal with the frequency and phase of the frequency fd, and controls the load fluctuation correction motor so that the two coincide. Rotate at an angular velocity of.

A drum load fluctuation correction control unit provided for each photosensitive drum controls the photosensitive drum at a constant angular velocity ω.
, The photosensitive drum provided in the image forming apparatus is controlled to an appropriate speed that does not cause slip even when there is eccentricity and variation in radius.

When the amount and timing of the load change on the photosensitive drum or the conveyor belt 915 are known, the drum load change correction control unit outputs a feedforward signal S6 corresponding to the amount and timing of the load change. Output from the controller 1306. As a result, the required gain of the feedback control system (so-called PLL control system) using the phase comparator 1307 of FIG. 13 can be reduced, so that a more stable and highly accurate control system can be configured.

In the drum load fluctuation correction control section, a signal proportional to the rotation speed of the photosensitive drum is detected from the load fluctuation correction motor 921 by the back electromotive force detector 1203 and fed back. In order to perform more stable control, a signal proportional to the rotation speed of the photosensitive drum is detected by a load fluctuation correction motor, and a speed feedback system is added. Since the PLL system shown in FIG. 13 controls a pulse output once for one rotation of the photosensitive drum, this speed feedback system is provided for the purpose of correcting fluctuations occurring within the pulse interval. Then
It is more stable and can be controlled with high accuracy.

The controller generates a signal S7 based on the speed ω calculated by the equation (24), and inputs the signal S7 to the DA converter 1407. The signal S8 DA-converted by the DA converter 1407 is compared with the back-EMF detected by the back-EMF detector 1203 whose phase is compensated by the phase compensator 1204. The back electromotive force is detected by subtracting the internal resistance r from the voltage of the terminal of the load fluctuation correction motor 921. Here, the current source type power amplifier 12
01 is used to improve control characteristics, and the phase compensator 12
04 is inserted to compensate for the stability of the system.

The drum load fluctuation correction control unit controls the load fluctuation correction motor to cancel the fluctuation of the load on the photosensitive drum based on the result of the comparison and rotate the photosensitive drum at the angular velocity ω. According to the above processing, the image forming apparatus of the present embodiment controls the entire system including the photosensitive drum and the transport belt by the motor 907, and the load variation of each photosensitive drum is used for correcting the load variation provided for each photosensitive drum. The correction can be made by the motor 921.

(Embodiment 4) Next, Embodiment 4 of the image forming apparatus will be described. The fourth embodiment can further improve the second and third embodiments. Form 2
Alternatively, even when the mode 3 is implemented, the present invention is effective for a system in which the slip easily occurs due to the control error. That is, if the frictional force between the photosensitive drum and the transport belt, between the photosensitive drum and the paper, or between the paper and the transport belt is weak, slip occurs even with a slight control error. Embodiment 4 described below provides a system with better control accuracy.

FIG. 1 shows a configuration for realizing the above idea.
5 and later. FIG. 15 is a block diagram for explaining a configuration for controlling the motor according to the fourth embodiment. The mechanical configuration of the image forming apparatus according to the fourth embodiment is the same as that described in the second or third embodiment with reference to FIG. For this reason, illustration and description of the configuration corresponding to FIG. 9 of the image forming apparatus according to the fourth embodiment will be omitted, and similar members will be assigned the same reference numerals.

The configuration shown in FIG. 15 corresponds to the photosensitive drum C9.
11 shows a drum C load fluctuation correction control system that corrects the load fluctuation of No. 01. The control system includes a sine wave oscillator 1401 for generating a superimposed sine wave for identification, an attenuator 1402 for attenuating an input signal, a sine wave oscillator 1401 and an attenuator 14.
Multiplier 140 that multiplies the signal outputted from
3, a switch 1405 that opens and closes based on a signal from the controller 1404, and further includes a current source type power amplifier 1406, a DA converter 1407, a load fluctuation correction motor 921, a rotary motor back electromotive force detector 1409, And a variable gain circuit 1411.

FIG. 16 is a block diagram of a system 1510 for detecting a waveform of a current flowing through a motor for driving the transport belt driving roller 906 in the control circuit of FIG. The motor current detection circuit 1500 includes a transport belt driving roller 906
Is a circuit for detecting a current flowing through a motor 907 for driving the motor. A system 15 for detecting a current waveform flowing through the motor
A band-pass filter 1501, an absolute value circuit 1502, which passes only signals of 10 fixed bands, a low-pass filter 1503, which passes only signals in a low-frequency range, a sample-and-hold circuit A1504, and a sample-and-hold circuit B15.
05, a code detection comparator 1506, and an AD converter 1507.

FIGS. 11 and 1 show specific examples of the above.
16 and 15 show circuits obtained by adding the above contents to FIG.
FIG. 15 shows a load fluctuation correction control system for the photosensitive drum, and FIG. 16 shows a power amplifier 1104 in FIG.
Is a current source type power amplifier so that a current proportional to the motor thrust can be detected. FIG. 17 is a timing chart for explaining these operations. Here, FIG. 13 shows another embodiment of FIG. 12, but does not show the sine wave oscillator 1401, attenuator 1402, multiplier 1403, switch 1405, etc. shown in FIG. These circuits can be inserted in the same manner as shown in FIG.

The following embodiment shows a case where the operation for detecting the control error of each load fluctuation correction control system is performed in a time-division manner. When the entire control system is moving, the error caused by the load fluctuation correction control system for the photosensitive drum in FIG.
In order to correct the reference signal of the load fluctuation correction control system with high accuracy in order to further reduce the transmission of the load fluctuation to the entire drive motor system of FIG.
Turns on the switch 1405. That is, to the input of the current source type power amplifier 1406, a signal input before the operation of this control mode, a signal obtained by attenuating the signal by the attenuator 1402, and a sine wave oscillator 1401
Is multiplied by a sine wave signal for detection of a constant frequency oscillating by the above. That is, the signal for measuring the load fluctuation transmitted to the entire drive motor side in FIG. 11 is modulated. Therefore, the load fluctuation correcting motor 9
Since a current corresponding to this flows through 21, a sinusoidal thrust fluctuation corresponding to this current occurs.

A sine wave having a magnitude corresponding to the transmitted load fluctuation can be detected from the output of the motor current detection circuit 1500 of the entire drive motor system in FIG. The slowly changing signal including DC other than the sine wave cannot be used as control information because it includes a load change transmitted from another photosensitive drum system. Further, since the load fluctuation caused by the load fluctuation correction control system error attached to each photosensitive drum system and the load fluctuation applied to the conveyor belt system are mainly mechanical, the components on the high frequency side are small, so If the frequency of the sine wave is selected on the high frequency side in the control band of the entire drive motor system, an error in the load fluctuation detection signal in the frequency component detected by the motor current detection circuit 1500 is small. When the specified sine wave signal component is detected by the bandpass filter 1501, a control error of the load fluctuation correction control system with high accuracy can be detected. Since the control signal to be input to the original current source type power amplifier 1406 is multiplied by a fixed ratio (constantly attenuated) and then multiplied by a sine wave, if the amplitude of the output of this bandpass filter is detected, , The transmission load can be predicted. The input voltage of the current source type power amplifier 1406 is controlled by the load fluctuation correction motor 92.
This can be said because it is almost proportional to the current flowing in 1. When the control error of the load fluctuation control system increases,
Since the load on the entire drive system in FIG. 11 increases, the amplitude of the output of the bandpass filter 1501 also increases. Therefore,
The amplitude is detected through the absolute value circuit 1502. The signal detection is stabilized through the low-pass filter 1503.

However, at this time, even if the transmission load amount is known, the direction of the transmission load is not known. That is, the error of the load fluctuation correction system is in the pulling direction with respect to the belt moving direction or in the opposite direction. Therefore, at the timing of changing the code detection gain in FIG. 17, the gain of the variable gain circuit 1411 for changing the reference signal to the control system in FIG. 15 is slightly changed by the gain data from the controller 1404, or the reference signal is slightly changed. Alternatively, the direction is detected by slightly shifting the appropriate reference signal frequency fd and the reference speed data S7 of each load variation correction system in FIG.
For example, if the detected sine wave output in the output of the entire drive motor current detection circuit is decreased when the speed of the photosensitive drum is decreased, it can be understood that the load fluctuation control system works in the direction of pulling the belt. That is, when pulling the belt, the pulling force is reduced. When the sine wave detection output amplitude is within the specified range, there is no need to perform this detection operation. That is, it is in a state in which it is hard to slip. Returning and executing may cause problems such as making a mistake in the determination of the sign.

Sample hold circuit A1504 in FIG.
Detects the output of the low-pass filter 1503 that is the amplitude of the sine wave signal before changing the gain of the variable gain circuit 1411 of each of the load fluctuation correction systems or the reference signal frequency fd or the reference speed data, and performs sample-and-hold B
Reference numeral 1505 detects the gain of the variable gain circuit 1411 or the sine wave signal amplitude after changing the reference signal frequency fd or the reference signal data. The direction of the transmission load can be determined by calculating the difference between the sample and hold circuits by the code detection comparator 1506. In this embodiment, the sample and hold circuit A1504
Although the transfer load is predicted from the output, the output of the sample and hold circuit B1505 may be used. In the case of the output of the sample and hold circuit A1504, since the information is before the reference signal frequency fd or the reference speed data is changed, a slight correction is required. Since the load variation transmission amount and its direction can be measured in this manner, the controller 1404 determines whether the load transmission amount is small based on the measured value so that the variable gain circuit 141 in FIG.
The reference signal frequency fd may be determined by setting the gain of 1 or setting the reference speed data S7 in FIG. 13 and setting the count values of the k (N + P) counter 1302 and the k · No counter 1305 in FIG. Here, the k · No counter 1305 is a presettable counter so that the frequency of the reference signal frequency fd can be freely set in the increase / decrease direction.

As described above, the load transmitted to the entire drive motor due to the error of the load fluctuation correction control system can be reduced.
Other load fluctuation correction systems may perform similar control at different times. When the force transmitted to the transport belt caused by the load variation correction control error is reduced in this manner, slippage between the photosensitive drum and the transport belt, between the photosensitive drum and the paper, or between the transport belt and the paper is eliminated.

Next, another example of the configuration of the load fluctuation correcting motor according to the second, third and fourth embodiments will be described. FIG.
Are rollers 1704 on the rotation axis of the photosensitive drum K904.
FIG. 13 is a diagram illustrating an example of a load fluctuation correction motor in which a roller 1701 that is directly rotated by a load fluctuation correction motor 1702 is brought into contact with a roller 1704 and rotates. Reference numeral 1703 indicates an encoder. The configuration shown in FIG.
02 has the advantage that the degree of freedom of the structure for transmitting the driving force to the photosensitive drum K904 can be increased.

FIG. 19 shows a motor 1804 for correcting load fluctuation.
FIG. 10 is a diagram illustrating an example of a load fluctuation correction motor in which a roller 1801 rotated by a spring is supported by a spring 1802.
According to the configuration shown in FIG.
804 can be sufficiently transmitted to the photosensitive drum K904.

FIG. 20 shows a disk-shaped transmission member 1901 directly connected to the photosensitive drum 1903 and a drive source 1904.
5 is a configuration example of a load fluctuation correction motor using a roller 1902 that stably transmits the driving force of the motor. At the contact portion between the transmission member 1901 and the roller 1902, the transmission member 1901 side is flat, and the roller 1902 is tapered to increase the number of contact portions so as to obtain stable transmission characteristics (characteristics of non-slip). ing. This drive source 1904
Is not parallel to a plane orthogonal to the rotation axis of the transmission member 1901.

The present invention is not limited to the embodiments described above. That is, Embodiment 2,
In the image forming apparatuses 3 and 4, the photosensitive drum 90 is provided.
When a flyhole is provided on the rotating shaft of the transfer belt drive roller 906, the transfer belt 1, 902, 903, and 904, the load fluctuation in the high-frequency region of the photosensitive drum or the conveyance belt can be further reduced, and the stable load fluctuation correction control or the whole. Drive control can be performed, and as a result, slip prevention is facilitated. However, if the flywheel is provided directly on the rotating shaft of the photosensitive drum or the driving roller, there is a disadvantage that the image forming apparatus becomes heavy.

To eliminate this disadvantage, for example,
As shown in FIG. 21, the flywheel 2001 is provided indirectly on the photosensitive drum (the photosensitive drum C901 in the figure) via a rotational force transmitting roller 2002. According to the configuration shown in FIG. 21, the moment of inertia of the flywheel 2001 as viewed from the drive shaft of the photosensitive drum is smaller than that of the photosensitive drum C901 as compared with the case where the inertial load is applied coaxially to the photosensitive drum. It is the square of the radius of the transmission roller 2002. Therefore, a relatively lightweight flywheel can be used to obtain a required moment of inertia, and the weight of the image forming apparatus can be reduced.

In the flywheel structure, the greater the weight of the outer peripheral portion, the greater the inertia can be given to the photosensitive drum. Therefore, by making the outer peripheral portion of the flywheel thicker than the inner peripheral portion, it is possible to reduce the weight while obtaining the necessary inertia.

In the image forming apparatuses according to the second, third, and fourth embodiments, the rotation angle detection encoder 908 that can detect the rotation angle as an absolute value is provided on the transport belt driving roller 906. However, the image forming apparatus of the present invention has
The reference mark provided on the front end position detector 9
The signal detected at step 09 may be replaced with a signal from an encoder (a belt movement amount detection encoder) that generates a pulse each time the transport belt 915 moves by a predetermined amount.

In the second, third, and fourth embodiments, a rotation angle detecting encoder 908 is provided on the transport belt driving roller 906.
Is provided, and the moving speed of the transport belt is controlled based on the rotation angle detected by the rotation angle detection encoder 908.
For example, the moving speed of the transport belt may be controlled in accordance with a speed signal detected by a rotation reference position detecting means or an encoder provided on the photosensitive drum.

In the second, third, and fourth embodiments, the roller is a photosensitive drum and the endless belt is a transport belt. However, the present invention is not limited to such a configuration. The present invention can also be applied to an application where it is desired to operate stably integrally with one rotating body and a belt that moves by pressing against these rotating bodies.

Further, the present invention can be applied to, for example, a multi-writing type image forming apparatus in which a latent image is simultaneously written on each photosensitive drum with a plurality of beams.

According to Embodiments 2, 3, and 4 described above, there is provided an image forming apparatus in which a slip does not easily occur between the photosensitive drum and the conveyor belt and an image without color shift can be stably formed. be able to. This is because the present invention can provide a control method and an apparatus for accurately canceling the load on the photosensitive drum and the conveyor belt so as not to cause slippage.

[0204]

According to the first aspect of the present invention, since the control means controls the operations of the driving roller driving means and the rotating body driving means in accordance with the load fluctuation of the belt, the control means controls the operation of the belt from the rotating body. As a result, the driving of the rotating body and the driving of the belt are controlled respectively, and the slip of the belt can be eliminated. The image forming apparatus has an effect that it can be easily applied to high-quality printing.

The invention according to claim 2 has an effect that the load applied to the belt can be detected by a simple device because the detection is performed without attaching a special detector.

According to the third aspect of the present invention, the load applied to the belt can be detected only by detecting the current supplied to the driving roller driving means, so that there is an effect that the load on the belt can be detected with a simple device. .

According to the fourth aspect of the present invention, since the identification signal generating means for generating the identification signal for facilitating the detection of the fluctuation of the load of the belt is provided, the load generated from any rotating body with a simple configuration. This has the effect of easily detecting whether or not there is a change.

According to the fifth aspect of the present invention, since the identification signal is a sine wave, it is possible to easily detect which of the rotating bodies the load fluctuation is generated from with a simple configuration.

[0209] According to the invention of claim 6, since the identification signal is added at a different timing for each of the rotating bodies, there is an effect that the load fluctuation of each rotating body can be easily identified.

According to the seventh aspect of the present invention, since the identification signal is a sine wave having a different frequency for each of the rotating bodies, there is an effect that load fluctuations of the respective rotating bodies can be easily and simultaneously distinguished.

The invention according to claim 8 is characterized in that a means for applying an inertial load to any of the belt, the driving roller driving means, and the rotating body driving means is added, so that the belt speed fluctuation caused by the load fluctuation is provided. The frequency band of the belt can be lowered, and stable control for reducing the slip of the belt can be easily performed.

According to the ninth aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if there is a variation in the shape of each rotator. It works.

According to the tenth aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if the radiators vary in radius. This has the effect.

According to the eleventh aspect of the present invention, the distance between the belt and the means for detecting the existing rotation angle and detecting the speed can be measured without newly providing the radius measurement means for the rotating body. Since the speed control reference signal can be generated based on the information obtained by the means for detecting the moving speed of the moving image, there is an effect that a simple image forming apparatus or the like can be formed.

According to a twelfth aspect of the present invention, there is provided a rotating device for comparing an analog signal continuously output from a speed detecting means of a rotating body even if the number of output pulses of a speed detector by a rotation angle detector is once per rotation. A body speed reference signal can be generated and controlled. In other words, the influence due to the variation in the radius of the rotating body is suppressed by comparing pulse signals, and stable control can be performed by comparing analog signals.
There is an effect that it is possible to provide stable rotation speed control without rotating the belt.

According to the thirteenth aspect of the present invention, the control error of the rotating body can be directly detected as a load applied to the belt, so that the correction can be performed with higher accuracy. Therefore, there is an effect that a device which is less slippery can be constructed.

According to the fourteenth aspect of the present invention, even if the rotating body has eccentricity or a variation in diameter, the control can be realized with higher accuracy, so that a stable and slip-free device can be realized.

According to the fifteenth aspect, it is possible to stably and easily realize image generation without image distortion or color shift.

According to the sixteenth aspect of the present invention, the operation of the driving roller and the rotating body is controlled according to the fluctuation of the load of the belt. Therefore, the driving of the rotating body and the belt is performed based on the load transmitted from the rotating body to the belt. Each of them is controlled, and the slip of the belt can be eliminated. The image forming method has an effect that it can be easily applied to high-quality printing.

According to the seventeenth aspect of the present invention, the load on the belt can be detected only by detecting the current supplied in the driving roller driving stage, so that the belt load can be detected with a simple device. .

According to the eighteenth aspect of the present invention, since the identification signal for facilitating the detection of the load fluctuation of the belt is generated, it is easy to detect which rotating body the load fluctuation is generated from with a simple configuration. It has the effect of being able to.

According to the nineteenth aspect of the present invention, since the identification signal is a sine wave, there is an effect that it is possible to easily detect from which rotating body the load fluctuation is generated by a simple configuration.

According to the twentieth aspect of the present invention, the identification signal is added at a different timing for each rotating body.
There is an effect that the load fluctuation of each rotating body can be easily identified.

According to the twenty-first aspect of the present invention, the identification signal is a sine wave having a different frequency for each of the rotating bodies.
There is an effect that the load fluctuation of each rotating body can be easily and simultaneously identified.

[0225] The invention according to claim 22, wherein the belt,
Since the drive roller driving means and the step of applying an inertial load to any of the rotating body driving means are added, the frequency band of the speed fluctuation of the belt caused by the load fluctuation can be reduced, and the slip of the belt can be reduced. There is an effect that it is possible to easily perform stable control for performing the control.

According to the twenty-third aspect of the present invention, it is possible to prevent the occurrence of slippage between the rotator and the belt, between the rotator and the paper, or between the paper and the belt, even if the shapes of the respective rotators vary. It works.

According to the twenty-fourth aspect, even if there is a variation in the radius of each rotating body, it is possible to prevent slippage between the rotating body and the belt, between the rotating body and the paper, or between the paper and the belt. This has the effect.

According to the twenty-fifth aspect of the present invention, even if a radius measuring means for the rotating body is not newly provided, the distance for moving the belt and the means for detecting the existing rotation angle and the speed are measured. Since the speed control reference signal can be generated based on the information obtained by the means for detecting the moving speed of the moving image, there is an effect that a simple image forming method can be realized.

According to a twenty-sixth aspect of the present invention, even when the number of output pulses of the speed detector by the rotation angle detector is one per rotation, the rotation is compared with an analog signal continuously output in the speed detection stage of the rotating body. A body speed reference signal can be generated and controlled. In other words, the influence of the radius variation of the rotating body can be suppressed by comparing pulse signals, and stable control can be performed by comparing analog signals, so that it is possible to provide stable rotating body speed control in which the belt does not slip. It works.

According to the twenty-seventh aspect of the present invention, the control error of the rotating body can be directly detected as a load applied to the belt, so that the correction can be performed with higher accuracy and a method that is less slippery can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a basic configuration of an image forming apparatus applied to a first embodiment of the present invention;

FIG. 2 is a view for explaining a tension roller shown in FIG. 1;

FIG. 3 is a diagram modeling the photosensitive drum shown in FIG. 1;

FIG. 4 is a diagram for explaining obtaining a transfer position of a latent image written on an eccentric photosensitive drum.

FIG. 5 is a diagram for describing a configuration for detecting a radius, an eccentric position, and a rotation angle of the photosensitive drum in the image forming apparatus according to the first embodiment;

FIG. 6 is a diagram illustrating a reference mark and a toner image formed by each photoconductor drum based on the reference mark.

FIG. 7 is a block diagram for explaining a configuration for controlling the configuration shown in FIG. 5;

FIG. 8 is a flowchart illustrating detection of a state of the image forming apparatus and adjustment of image forming conditions performed by the image forming apparatus illustrated in FIG. 1;

FIG. 9 is a diagram illustrating a main part of an image forming apparatus according to a second, third, or fourth embodiment of the present invention;

FIG. 10 is a view for explaining the load fluctuation correction motor shown in FIG. 9;

FIG. 11 is a block diagram for describing control of a belt or a drive roller by a rotation angle detection encoder and a belt drive motor.

FIG. 12 is a block diagram illustrating a configuration of a drum load fluctuation correction control unit that controls a load fluctuation of a photosensitive drum.

FIG. 13 is a block diagram illustrating a configuration of a drum load fluctuation correction control unit that controls a load fluctuation of a photosensitive drum, which is more improved.

FIG. 14 is a block diagram illustrating an fd generation unit that generates the clock frequency fd shown in FIG.

FIG. 15 is a block diagram illustrating a configuration for controlling a motor of the image forming apparatus according to the fourth embodiment.

16 is a block diagram for explaining a circuit for detecting a waveform generated in a drive roller driving motor current according to a control error of the load fluctuation correction system shown in FIG.

FIG. 17 is a timing chart of the block diagrams shown in FIGS. 15 and 16;

FIG. 18 is a diagram showing another configuration example of the load fluctuation correction motor.

FIG. 19 is a diagram showing another example of the configuration of the load variation correction motor.

FIG. 20 is a diagram showing another configuration example of the load fluctuation correction motor.

FIG. 21 is a diagram illustrating another configuration example of the image forming apparatus in which the flywheel is attached to the photosensitive drum in the second, third, and fourth embodiments.

FIG. 22 is a diagram illustrating a transfer position of a conventional image forming apparatus.

[Explanation of symbols]

101, 102, 103, 104, 301, 401, 9
01, 902, 903, 904 Photoconductor drum 105 Follower roller 106 Drive roller 107, 108, 109, 110 Corona charger for transfer 111, 112, 113, 911, 912, 913 Roller 114, 914 Tension roller 115, 302, 402, 915 Conveyor belt 501, 908, 1303 Rotation angle detection encoder 506 Reference position error detector 507 Linear encoder 508 Paper passage detector 509, 909 Tip position detector 510 Timing mark 511 Reference mark 512 Paper passage area 521, 522, 523, 524 Eccentricity detector 701 Control unit 702 Writing unit control unit 703 Memory 906 Conveyor belt drive roller 907 Motor 921, 922, 923, 924 Load fluctuation correction motor 931, 932, 33,934 Rotation angle reference position detector 1001,1902 Roller 1100 Control circuit 1101 Phase comparator 1102 Charge pump 1104 Power amplifier 1105 Phase compensator 1106 fV converter 1107 Encoder pulse detector 1201,1406 Current source type power amplifier 1203 Back electromotive force detector 1202, 1204 Phase compensator 1205 Comparator 1208 Charge pump 1301 Frequency synthesizer 1302 k (N + P) counter 1303 PLL processing unit 1304 Signal processing unit 1305 k / No counter 1306, 1404 Controller 1307 Phase comparator 1309 Loop filter 1401 sine wave oscillator 1402 attenuator 1403 multiplier 1405 switch 1407 DA converter 1409 rotary motor back electromotive force detector 1 11 variable gain circuit 1500 motor current detecting circuit 1501 bandpass filters 1502 the absolute value circuit 1503 low-pass filter 1504, 1505 sample-and-hold circuit 2001 flywheel 2002 rotational force transmission roller

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 15/16 G03G 21/00 350 3F049 21/00 350 372 3J049 F term (reference) 2H027 DA01 DA32 DA41 DE03 EB04 EC10 ED02 EE01 EE02 EE03 EE04 EE07 2H030 AA01 AB02 AD17 BB42 BB46 BB53 BB56 BB71 2H032 AA15 BA01 BA09 BA18 BA23 2H035 CA07 CB01 CD13 CG01 CG03 2H071 BA42 BA43 CA01 CA02 CA05 DA26 DA31 DA32 3F0 EA03 BB03 A03 BB03 A03 BB03

Claims (27)

[Claims] 1. An image forming apparatus comprising: at least one rotator directly or indirectly pressed against a belt and driven by the movement of the belt; and a driving roller for driving the belt. A driving roller driving unit that drives the driving roller; a rotating body driving unit that drives the rotating body; a load fluctuation detecting unit that detects a load fluctuation of the belt; and the driving roller according to a load fluctuation of the belt. An image forming apparatus comprising: a driving unit or a control unit that controls an operation of the rotating unit driving unit. 2. The image forming apparatus according to claim 1, wherein the load fluctuation detecting unit is provided in the control unit that controls the driving roller driving unit. 3. The image forming apparatus according to claim 1, wherein the load fluctuation detecting unit detects a current supplied to the driving roller driving unit. 4. The apparatus according to claim 1, wherein said rotating body driving means includes an identification signal generating means for generating an identification signal for facilitating detection of load fluctuation of said belt.
The image forming apparatus according to claim 3. 5. The image forming apparatus according to claim 4, wherein the identification signal is a sine wave. 6. The image forming apparatus according to claim 4, wherein the identification signal generation unit adds the identification signal at a different timing for each of the rotating bodies. 7. The image forming apparatus according to claim 4, wherein the identification signal is a sine wave having a different frequency for each of the rotating bodies. 8. The belt, the driving roller driving unit,
The image forming apparatus according to any one of claims 1 to 7, wherein a means for applying an inertial load is added to any one of the rotating body driving means. 9. At least one rotator that rotates while being pressed directly or indirectly onto the belt, wherein the speed detector detects at least one of a moving speed of the belt and a speed related to the rotator, and control. And a speed setting means for setting the moving speed of the belt and the rotation speed of the rotating body to a speed at which the belt and the rotating body can move integrally with each other in the system having the speed detecting means and the controlling means. An image forming apparatus comprising: 10. The apparatus according to claim 9, wherein said speed setting means is means for generating a reference signal for determining a speed of said rotating body control means in accordance with a diameter (radius) of said rotating body. Image forming apparatus. 11. The speed setting unit according to claim 9, wherein the speed setting unit generates speed reference information based on information obtained from the speed detection unit of the rotating body and the belt moving speed detection unit. An image forming apparatus according to claim 1. 12. The speed setting means comprises a pulse signal for synchronizing with a pulse signal output from the speed detection means, or an analog reference signal for comparing with an analog signal generated from the speed detection means. Claim 9, Claim 10, or Claim 1 characterized by the above-mentioned.
2. The image forming apparatus according to 1. 13. The speed setting means according to claim 11, wherein a load fluctuation on the belt caused by a control error of the rotating body control means is corrected by the information obtained by the load fluctuation detecting means. 9 to claim 1
3. The image forming apparatus according to any one of 2. 14. The device according to claim 1, wherein the contact portion between the belt and the rotating body has a configuration that is a vertex in the belt direction in a circular cross section of the rotating body. The image forming apparatus according to one of the above. 15. The rotating body is a photosensitive drum on which a latent image is written, and the belt presses a sheet against the photosensitive drum to form a toner based on the written latent image. A transfer belt that transfers the image onto a sheet and conveys the sheet, or the belt presses a toner image formed based on a latent image written on the photosensitive drum against the photosensitive drum. The image forming apparatus according to any one of claims 1 to 14, wherein the image forming apparatus is an intermediate transfer belt that transfers images directly. 16. An image forming apparatus comprising: at least one rotating member directly or indirectly pressed against a belt and driven by the movement of the belt; and a driving roller for driving the belt. A driving roller driving step of driving the driving roller; a rotating body driving step of driving the rotating body; a load fluctuation detecting step of detecting a load fluctuation of the belt; and a load of the belt. Controlling the operation of the driving roller or the rotator according to the fluctuation. 17. The image forming method according to claim 16, wherein in the load variation detecting step, a current supplied to drive the driving roller is detected. 18. The image forming method according to claim 16, wherein in the rotating body driving step, an identification signal for facilitating detection of load fluctuation of the belt is generated. 19. The image forming method according to claim 18, wherein the identification signal is a sine wave. 20. The image forming method according to claim 18, wherein the identification signal is added at a different timing for each of the rotating bodies. 21. The apparatus according to claim 18, wherein the identification signal is a sine wave having a different frequency for each of the rotating bodies.
Alternatively, the image forming method according to claim 19. 22. The method according to claim 16, further comprising the step of applying an inertial load to any one of said belt, said driving roller driving means, and said rotating body driving means.
2. The image forming method according to any one of 1. 23. An image forming method for controlling at least one rotating body that rotates while being pressed directly or indirectly on a belt, wherein at least one of a moving speed of the belt and a speed related to the rotating body. A speed detection step and a control step of detecting the speed, wherein in the system for performing the speed detection step and the control step, the movement speed of the belt and the rotation speed of the rotating body are integrated with the belt and the rotating body. An image forming method, comprising a speed setting step of setting a moving speed. 24. The image forming method according to claim 23, wherein in the speed setting step, a reference signal for determining a speed in the control step according to a diameter (radius) of the rotating body is generated. . 25. The speed setting step according to claim 23, wherein the speed setting step generates speed reference information based on information obtained from the rotating body speed detecting step and the belt moving speed detecting step. 2. The image forming method according to 1., 26. The speed setting step includes a pulse signal for synchronizing with a pulse signal output in the speed detection step, or an analog reference signal for comparison with an analog signal generated in the speed detection step. 26. The image forming method according to claim 23, wherein the image forming method comprises: 27. The speed setting step according to claim 23, wherein a load fluctuation on the belt caused by a control error in the rotating body control step is corrected in the speed setting step based on information obtained in the load fluctuation detecting step. Claim 23 to Claim 2
7. The image forming method according to any one of 6.