JP4312570B2 - Rotating body drive control method and apparatus, image forming apparatus, process cartridge, program, and recording medium - Google Patents

Description

  The present invention detects the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source that drives the controlled rotor, and controls the rotational drive source on the basis of the detection result, thereby rotating the controlled rotational body. The present invention relates to a rotating body drive control method and an apparatus for controlling the same. The present invention also relates to an image forming apparatus such as a copying machine, a printer, and a FAX, and a process cartridge provided with such a rotational drive control device. Furthermore, the present invention relates to a program used for a computer constituting such a rotational drive control device and a recording medium on which the program is recorded.

Conventionally, this type of image forming apparatus detects a rotational angular displacement or rotational angular velocity of a rotating shaft of a motor that drives a photosensitive drum as a latent image carrier, and feedback controls the rotation of the motor based on the detection result. What to do is known. According to this image forming apparatus, by rotating the motor at a constant speed while suppressing fluctuations in the rotation speed of the motor, image position deviation, color deviation, etc. caused by fluctuations in the rotation speed of the photosensitive drum caused by fluctuations in the rotation speed of the motor Image quality deterioration can be prevented.
However, even if the motor is rotated at a constant speed, if there is an eccentricity or accumulated tooth pitch error in the drive gear as a drive transmission rotating member attached to the rotating shaft of the photosensitive drum, the photosensitive drum rotates once. Periodic rotational speed fluctuations will occur. Thus, an image forming apparatus is known in which a rotary encoder that detects a rotational angular velocity is attached to the rotating shaft of a photosensitive drum (see, for example, Patent Document 1). In this image forming apparatus, the rotation of the motor is feedback controlled so that the photosensitive drum rotates at a stable speed using the detection result of the rotary encoder attached to the rotating shaft of the photosensitive drum.
JP-A-12-231305

However, in order to obtain a sufficient suppression effect on the rotational speed fluctuation of the photosensitive drum due to the eccentricity of the drive gear using the rotary encoder, it is necessary to use a high-precision rotary encoder, which increases the cost. There was a problem that.
This problem is not only the case where the controlled object rotating body is a photosensitive drum, but also an endless belt body such as an intermediate transfer body used in the image forming apparatus and a driving roller of the belt body are controlled object rotating bodies. This also occurs in some cases.

  The present invention has been made in view of the above problems. The purpose of the rotating body is to be able to suppress fluctuations in the rotational speed of one rotation cycle of the rotating body to be controlled due to the eccentricity of the drive transmission rotating body without using a high-accuracy rotary encoder that causes high costs. A drive control method and apparatus thereof are provided. Another object of the present invention is to provide an image forming apparatus provided with such a rotary body drive control device, a process cartridge, a program used for the rotary body drive control device, and a recording medium on which the program is recorded.

In order to achieve the above-mentioned object, the invention according to claim 1 is the rotational angular displacement or rotation of the rotation shaft of the rotation drive source that generates the rotation drive force transmitted to the controlled object rotation body via the plurality of drive transmission rotation bodies. A rotational drive control method for controlling the rotation of the rotational body to be controlled by detecting an angular velocity and controlling the rotational drive source based on the detection result, wherein two or more types of control patterns having different drive conditions The rotation drive source is controlled by the control unit, and when the control object is controlled by each control pattern , the rotation of the control object rotator is rotated among the plurality of drive transmission rotators together with the rotation time when the control object rotator rotates a predetermined rotation angle. at least one drive transmission rotary member is in a position other than the axis to measure the rotation time at the time of rotating the default rotation angle, the controlled object rotating body on the basis of the measurement results of these rotation time, and the measurement target driving Den Obtain an amplitude of the rotational speed fluctuation of one rotation period of the rotating body and the phase, the control target rotational member, and controls said rotation driving source based on the amplitude and phase of the rotational speed fluctuation of the measurement target drive transmitting rotary member It is characterized by this .
The invention of claim 2 is the rotation driving control method according to claim 1, successively, and the measurement and the amplitude of the rotation time from the direction rotation period of the plurality of rotating bodies is to be measured the rotation time is greater The rotational drive source is controlled based on the phase.
According to a third aspect of the present invention, in the rotary body drive control method according to the first or second aspect , the rotation period of the rotation shaft of the rotation drive source, the rotation period of the drive transmission rotation body, and the rotation target of the control object rotation body. The ratio between the rotation periods is a natural number ratio, respectively.
According to a fourth aspect of the present invention, in the rotating body drive control method according to the third aspect , at least one rotation period of the plurality of drive transmission rotating bodies is Tr, a rotation period of the controlled object rotating body is To, and the predetermined rotation When the angle is θo and the natural number is n, the following equation is established.
n × Tr = To × (θo / 2π)
According to a fifth aspect of the present invention, in the rotating body drive control method according to any one of the first to fourth aspects, after the control of the rotational drive source based on the amplitude and phase of the rotational speed fluctuation is started, Measurement is performed, and the amplitude or phase of the rotational speed fluctuation of one rotation period of the controlled rotating body is obtained based on the measurement result. Based on the amplitude or phase, the rotational speed fluctuation used for controlling the rotational drive source is determined. It is characterized by correcting the amplitude and phase.
According to a sixth aspect of the present invention, in the rotating body drive control method according to any one of the first to fifth aspects, the predetermined rotational angle is π [rad].

Also, the invention of claim 7 includes a rotary drive source, the plurality of drive transmitting rotary member for transmitting a rotational driving force of the rotary driving source to the control target rotational member, the rotational angular displacement of the rotary shaft of the rotary drive source Or the 1st detection means which detects a rotation angular velocity, and the rotary body drive control apparatus which controls rotation of this controlled object rotary body by controlling this rotational drive source based on the detection result of this 1st detection means Because
Second detection for detecting at least one drive transmission rotator at a position other than the rotation axis of the control target rotator among the plurality of drive transmission rotators together with the control target rotator rotating a predetermined rotation angle. And the rotation drive source is controlled by two or more types of control patterns having different driving conditions, and the controlled object rotator is rotated based on the detection result of the second detection means at the time of control by each control pattern. Rotation time when at least one drive transmission rotator at a position other than the rotation axis of the control target rotator rotates a predetermined rotation angle among the plurality of drive transmission rotators together with the rotation time when rotating the corner And, based on the measurement results of these rotation times, obtain the amplitude and phase of the rotational speed fluctuation of one rotation cycle of the controlled rotating body,
And a control means for controlling the rotational drive source on the basis of the amplitude and phase of the rotational speed fluctuations of the control object rotator and the drive transmission rotator to be measured .
Further, the invention according to claim 8 is the rotating body drive control device according to claim 7 , wherein the control means sequentially sets the rotation times of the plurality of rotating bodies whose rotation times are measured in descending order. Measurement and control of the rotational drive source based on the amplitude and phase are performed.
The invention according to claim 9 is the rotating body drive control device according to claim 7 or 8 , wherein the rotation period of the rotation shaft of the rotation drive source, the rotation period of the drive transmission rotation body, and the rotation object of the control object rotation body. The ratio between the rotation periods is a natural number ratio, respectively.
Further, the invention of claim 10 is the rotating body drive control device according to claim 9 , wherein at least one rotation period of the plurality of drive transmission rotating bodies is Tr, the rotation period of the controlled object rotating body is To, and the predetermined rotation A rotating body drive control device, wherein the following equation is established when the angle is θo and the natural number is n.
n × Tr = To × (θo / 2π)
According to an eleventh aspect of the present invention, in the rotating body drive control device according to any one of the seventh to tenth aspects, the control means starts control of the rotational drive source based on the amplitude and phase of the rotational speed fluctuation. The rotation time is measured, the amplitude or phase of the rotation speed fluctuation of one rotation period of the controlled object rotating body is obtained based on the measurement result, and used for controlling the rotation drive source based on the amplitude or phase. The amplitude and phase of the rotational speed fluctuation are corrected.
According to a twelfth aspect of the present invention, in the rotating body drive control device according to any of the seventh to eleventh aspects, the predetermined rotation angle is π [rad].
The invention according to claim 13 is the rotating body drive control device according to any one of claims 7 to 12 , wherein the second detection means has a longitudinal central portion attached to the rotation shaft of the controlled object rotating body. It is characterized by using a rod-shaped member having a detected portion at a direction end and a detection device that detects the detected portion at a position where the detected portion of the rod-shaped member passes.
Further, the invention of claim 14 is directed to a rotational drive source, a drive transmission rotator that transmits the rotational drive force of the rotational drive source to the controlled rotational body, and a rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source. And a rotating body drive control device that controls the rotation of the rotating object to be controlled by controlling the rotation driving source based on the detection result of the first detecting means. ,
The second detection means for detecting that the rotating body to be controlled rotates at a predetermined rotation angle, and the rotational drive source is controlled by two or more types of control patterns having different drive conditions, and at the time of control by each control pattern, Based on the detection result of the second detection means, the rotation time when the control object rotating body rotates a predetermined rotation angle is measured, and one rotation period of the control object rotating body is measured based on the measurement result of each rotation time. And a control means for controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, wherein the second detection means is a rotation of the rotating object to be controlled. A rod-shaped member having a longitudinal center portion attached to the shaft and having a sensed portion at the longitudinal end, and a detection device that detects the sensed portion at a position where the sensed portion of the rod-shaped member passes is configured. It is characterized by
The invention according to claim 15 is the rotating body drive control device according to any one of claims 7 to 12 , wherein the second detecting means has a center portion attached to a rotating shaft of the controlled object rotating body. A plate-like member having a detected part in a part of the rotation direction at a position away from the sensor, and a detection device that detects the detected part at a position where the detected part of the plate-like member passes. It is characterized by.
According to a sixteenth aspect of the present invention, there is provided a rotational drive source, a drive transmission rotator for transmitting the rotational drive force of the rotational drive source to the controlled rotational body, and a rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source. And a rotating body drive control device that controls the rotation of the rotating object to be controlled by controlling the rotation driving source based on the detection result of the first detecting means. ,
The second detection means for detecting that the rotating body to be controlled rotates at a predetermined rotation angle, and the rotational drive source is controlled by two or more types of control patterns having different drive conditions, and at the time of control by each control pattern, Based on the detection result of the second detection means, the rotation time when the control object rotating body rotates a predetermined rotation angle is measured, and one rotation period of the control object rotating body is measured based on the measurement result of each rotation time. And a control means for controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, wherein the second detection means is a rotation of the rotating object to be controlled. A plate-shaped member having a detected portion at a part in the rotation direction at a position apart from the central portion with the central portion attached to the shaft, and the detected portion is detected at a position where the detected portion of the plate-shaped member passes. Configured with a detection device that The one in which the features.
According to a seventeenth aspect of the present invention, in the rotating body drive control device according to any of the seventh to twelfth aspects, the second detection means is provided in a part of the outer circumferential surface of the controlled object rotating body in the rotational direction. And a detection device that detects the detected part at a position through which the detected part passes.
Further, the invention of claim 18 is directed to a rotational drive source, a drive transmission rotator that transmits a rotational drive force of the rotational drive source to a controlled rotational body, and a rotational angular displacement or rotational angular velocity of a rotational shaft of the rotational drive source. And a rotating body drive control device that controls the rotation of the rotating object to be controlled by controlling the rotation driving source based on the detection result of the first detecting means. ,
The second detection means for detecting that the rotating body to be controlled rotates at a predetermined rotation angle, and the rotational drive source is controlled by two or more types of control patterns having different drive conditions, and at the time of control by each control pattern, Based on the detection result of the second detection means, the rotation time when the control object rotating body rotates a predetermined rotation angle is measured, and one rotation period of the control object rotating body is measured based on the measurement result of each rotation time. And a control means for controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, wherein the second detection means is an outer periphery of the controlled object rotating body. It is characterized by comprising a detected part provided in a part of the rotation direction on the surface and a detecting device for detecting the detected part at a position through which the detected part passes.
According to a nineteenth aspect of the present invention, in the rotating body drive control device according to any one of the seventh to twelfth aspects, the second detecting means cuts out a part of the rotation direction of the rotating shaft of the controlled object rotating body. And a detection device that detects the detected portion at a position through which the detected portion passes.
According to a twentieth aspect of the present invention, there is provided a rotational drive source, a drive transmission rotator that transmits the rotational drive force of the rotational drive source to the controlled rotational body, and the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source And a rotating body drive control device that controls the rotation of the rotating object to be controlled by controlling the rotation driving source based on the detection result of the first detecting means. ,
The second detection means for detecting that the rotating body to be controlled rotates at a predetermined rotation angle, and the rotational drive source is controlled by two or more types of control patterns having different drive conditions, and at the time of control by each control pattern, Based on the detection result of the second detection means, the rotation time when the control object rotating body rotates a predetermined rotation angle is measured, and one rotation period of the control object rotating body is measured based on the measurement result of each rotation time. And a control means for controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, wherein the second detection means is a rotation of the rotating object to be controlled. It is characterized in that it is configured using a detected portion formed by cutting out a part of the rotation direction of the shaft and a detecting device that detects the detected portion at a position where the detected portion passes. is there.
The invention according to claim 21 is the rotating body drive control device according to any one of claims 13 to 20 , wherein the detection device is provided at a plurality of positions separated by equal angles in the rotation direction of the detected portion. It is a feature.
The invention according to claim 22 is the rotary body drive control device according to any one of claims 13 to 20 , wherein a plurality of the detected parts are provided so as to be separated by an equal angle in the rotation direction. It is.
The invention of claim 23 is characterized in that, in the rotating body drive control device of claim 22 , one of the plurality of detected parts is provided so as to be distinguishable from other detected parts. Is.

According to a twenty-fourth aspect of the present invention, there is provided a latent image carrier, a latent image forming unit that forms a latent image on the latent image carrier, a developing unit that develops a latent image on the latent image carrier, and the latent image carrier. an image forming apparatus having a transfer unit for transferring the transfer material developed image on the image bearing member, a rotary body drive control device for controlling the rotation of the latent image bearing member, any claims 7 to 23 The rotary body drive control device is provided.
According to a twenty-fifth aspect of the present invention, there is provided a latent image carrier, a latent image forming unit that forms a latent image on the latent image carrier, a developing unit that develops a latent image on the latent image carrier, and the latent image carrier. An image forming apparatus comprising transfer means for transferring a visible image on an image bearing member to a transfer material, and an endless belt member stretched around a plurality of support rotating members, Among them, the rotating body drive control device according to any one of claims 7 to 23 is provided as a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body.
According to a twenty-sixth aspect of the present invention, in the image forming apparatus according to the twenty- fifth aspect, the second detecting means detects the plurality of supporting rotating bodies instead of detecting that the driving rotating body rotates at a predetermined rotation angle. Among them, the driven rotating body driven by the belt body is detected to rotate at a predetermined rotation angle.
According to a twenty-seventh aspect of the present invention, there is provided a latent image carrier, a latent image forming unit that forms a latent image on the latent image carrier, a developing unit that develops a latent image on the latent image carrier, and the latent image carrier. In an image forming apparatus comprising transfer means for transferring a visible image on an image carrier to a transfer material, and an endless belt member that is stretched around a plurality of support rotating members,
As a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body among the plurality of supporting rotating bodies, a rotational driving source and the rotational driving force of the rotational driving source are applied to the controlled rotating body. A drive transmission rotating body for transmitting, a first detection means for detecting a rotational angular displacement or a rotational angular velocity of a rotational shaft of the rotational drive source, and controlling the rotational drive source based on a detection result of the first detection means Thus, the rotating body drive control device for controlling the rotation of the controlled object rotating body, the second detecting means for detecting that the controlled object rotating body rotates at a predetermined rotation angle, and the drive condition are mutually The rotation drive source is controlled by two or more different control patterns, and the rotation when the controlled object rotating body rotates the predetermined rotation angle based on the detection result of the second detection means at the time of control by each control pattern Measure the time of each rotation time Control means for obtaining the amplitude and phase of the rotational speed fluctuation in one rotation cycle of the controlled rotating body based on the measurement result, and controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, Instead of detecting that the drive rotator rotates at a predetermined rotation angle, the second detection means is configured such that a driven rotator driven by the belt body among the plurality of support rotators rotates at a predetermined rotation angle. It is characterized by including a rotating body drive control device for detecting the above.
The invention of claim 28 provides a latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and the latent image carrier. An image forming apparatus comprising a transfer means for transferring a visible image on an image carrier to a transfer material, and an endless belt member stretched around a plurality of support rotating members, and controlling the rotation of the belt member A rotating body drive control device according to any one of claims 7 to 23 is provided as the rotating body drive control device.
The invention of claim 29 is the image forming apparatus according to claim 26 or 27, the default rotation angle is a rotation angle corresponding to the natural fraction rotation of half of the belt body, the該既constant rotation angle A detected portion for detecting rotation is provided on the belt body.
According to a thirty- third aspect of the present invention, in the image forming apparatus according to the twenty-sixth or twenty-seventh aspect , the predetermined rotation angle is a rotation angle corresponding to a natural number of one-half rotation of a half circumference of the belt body, and the plurality of support rotations The rotation period of one driven rotating body that follows the belt body among the bodies is a natural number of the rotation period of the belt body, and the second detection means detects one rotation of the driven rotating body. Thus, the belt body is configured to detect the rotation of the predetermined rotation angle.
The invention according to a thirty-first aspect is the image forming apparatus according to the twenty-sixth or twenty-seventh aspect , wherein the first detecting means is configured to support the plurality of supports in place of the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source. The rotational angle displacement or rotational angular velocity of one driven rotating body driven by the belt body among the rotating bodies is detected, and the second detection means detects the rotation of the other driven rotating body. The belt body is configured to detect rotation of the predetermined rotation angle.
The invention according to a thirty-second aspect is the image forming apparatus according to any one of the twenty-fifth to thirty-first aspects, wherein the transfer means transfers the visible image on the latent image carrier onto a transfer material via an intermediate transfer member. The belt body is the intermediate transfer body.
The invention according to claim 33 is the image forming apparatus according to claim 24 , wherein a plurality of the latent image carriers are arranged so as to be arranged along the surface movement direction of the transfer material, and the control means includes each latent image. The amplitude and phase of the rotational speed fluctuation in one rotation period of the carrier are obtained, and based on the amplitude and phase of the rotational speed fluctuation, the rotational speed fluctuation of each latent image carrier with respect to the same location on the transfer material is the same condition. Thus, the rotational drive source corresponding to each latent image carrier is controlled.
The invention according to claim 34 is the image forming apparatus according to claim 32 , wherein a plurality of the latent image carriers are arranged along the surface moving direction of the intermediate transfer member, and the rotational driving force of the drive source is set to the intermediate driving force. A drive transmission rotator that transmits to the transfer body is provided, and the rotation cycle of the drive transmission rotator is equal to the time during which the surface of the intermediate transfer body passes through the pitch between the latent image carriers. .
The invention according to claim 35 is the image forming apparatus according to claim 32 , wherein a plurality of the latent image carriers are arranged along the surface movement direction of the intermediate transfer member, and the rotational driving force of the drive source is set to the intermediate driving force. A drive transmission rotator for transmitting to the transfer body, the rotation cycle of the drive transmission rotator being from the primary transfer position facing the latent image carrier to the secondary transfer position facing the transfer material; It is characterized by being equal to the time for the surface to move.
The invention according to claim 36 is the image forming apparatus according to any one of claims 24 to 35 , further comprising drive transmission means for transmitting the rotational drive force of the drive source to the rotating object to be controlled, wherein the first detection means comprises: Instead of the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational drive source, the rotational angular displacement or rotational angular velocity of the output shaft of the speed increasing mechanism composed of a gear provided on the rotational shaft of the rotating body to be controlled is detected. It is characterized by comprising.
The invention according to claim 37 provides a latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and the latent image carrier. In an image forming apparatus comprising transfer means for transferring a visible image on an image carrier to a transfer material,
As a rotating body drive control device that controls the rotation of the latent image carrier, a rotation driving source, a drive transmission rotating body that transmits the rotation driving force of the rotation driving source to a rotating object to be controlled, and the rotation of the rotation driving source The first detection means for detecting the rotational angular displacement or the rotational angular velocity of the shaft, and the rotation drive source is controlled based on the detection result of the first detection means, thereby controlling the rotation of the controlled object rotating body. A rotary body drive control device, wherein the rotary drive source is controlled by a second detection means for detecting that the controlled rotor rotates at a predetermined rotation angle, and two or more control patterns having different drive conditions. Then, at the time of control by each control pattern, the rotation time when the controlled object rotating body rotates the predetermined rotation angle is measured based on the detection result of the second detection means, and based on the measurement result of each rotation time Of one rotation cycle of the controlled rotating body Rolling obtain an amplitude and phase of the speed fluctuation, a rotary body drive control device being characterized in that a control means for controlling the rotation driving source based on the amplitude and phase of the rotation velocity fluctuation,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. It has a rotating body drive control device configured to detect a displacement or a rotational angular velocity.
The invention of claim 38 provides a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, a developing means for developing the latent image on the latent image carrier, and the latent image carrier. In an image forming apparatus comprising transfer means for transferring a visible image on an image carrier to a transfer material, and an endless belt member that is stretched around a plurality of support rotating members,
As a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body among the plurality of supporting rotating bodies, a rotational driving source and the rotational driving force of the rotational driving source are applied to the controlled rotating body. A drive transmission rotating body for transmitting, a first detection means for detecting a rotational angular displacement or a rotational angular velocity of a rotational shaft of the rotational drive source, and controlling the rotational drive source based on a detection result of the first detection means Thus, the rotating body drive control device for controlling the rotation of the controlled object rotating body, the second detecting means for detecting that the controlled object rotating body rotates at a predetermined rotation angle, and the drive condition are mutually The rotation drive source is controlled by two or more different control patterns, and the rotation when the controlled object rotating body rotates the predetermined rotation angle based on the detection result of the second detection means at the time of control by each control pattern Measure the time of each rotation time Measuring obtains the amplitude and phase of the rotation velocity fluctuation of one rotation period of the controlled object rotating body on the basis of the result, and a control means for controlling the rotation driving source based on the amplitude and phase of the rotation velocity fluctuation,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. It has a rotating body drive control device configured to detect a displacement or a rotational angular velocity.
The invention of claim 39 provides a latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and the latent image carrier. In an image forming apparatus comprising transfer means for transferring a visible image on an image carrier to a transfer material, and an endless belt member that is stretched around a plurality of support rotating members,
As a rotary body drive control device that controls the rotation of the belt body, a rotary drive source, a drive transmission rotary body that transmits the rotary drive force of the rotary drive source to the controlled rotary body, and a rotary shaft of the rotary drive source A first detecting means for detecting a rotational angular displacement or a rotational angular velocity, and a rotating body for controlling the rotation of the controlled rotating body by controlling the rotation drive source based on a detection result of the first detecting means. A drive control device for controlling the rotational drive source with a second detection means for detecting that the controlled rotating body rotates at a predetermined rotational angle, and two or more control patterns having different drive conditions; At the time of control by each control pattern, the rotation time when the controlled object rotating body rotates the predetermined rotation angle is measured based on the detection result of the second detection means, and the control is performed based on the measurement result of each rotation time. One rotation cycle of the target rotating body It obtains the amplitude and phase of speed variations, and control means for controlling the rotation driving source based on the amplitude and phase of the rotation velocity fluctuation,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. It has a rotating body drive control device configured to detect a displacement or a rotational angular velocity.
The invention of claim 40 is a process cartridge for use in the image forming apparatus of claim 24 or 33 , which includes the controlled object rotating body and the rotating body drive control device, and is attached to and detached from the image forming apparatus main body. It is configured to be possible.

Further, the invention of claim 41 detects a rotational angular displacement or a rotational angular velocity of a rotational shaft of a rotational drive source that generates a rotational driving force transmitted to a controlled subject rotational body via a plurality of drive transmission rotational bodies, A program used in a computer constituting a rotating body drive control device for controlling the rotation of the rotating object to be controlled by controlling the rotation drive source based on a detection result, wherein two or more types of driving conditions differ from each other The step of controlling the rotation drive source with a control pattern, and the control target of the plurality of drive transmission rotators together with the rotation time when the control target rotator rotates a predetermined rotation angle at the time of control by each control pattern a step in which at least one drive transmission rotary member is in a position other than the rotation axis of the rotating body to measure the rotation time at the time of rotating the default rotation angle, the measurement results of these rotation time Controlled object rotating body Zui, and a step of determining the amplitude and phase of the rotation velocity fluctuation of one rotation period of the drive transmission rotary member to be measured, the rotation speed variation, and the amplitude of the measurement target of the drive transmission rotating body and And causing the computer to execute the step of controlling the rotational drive source based on the phase .
The invention according to claim 42 is the program according to claim 41 , wherein, based on the measurement of the rotation time and the amplitude and phase in order from the larger rotation period of the plurality of rotating bodies to be measured for the rotation time. The rotary drive source is controlled.
The invention according to claim 43 is the program according to claim 41, wherein the step of measuring the rotation time after starting the control of the rotation drive source based on the amplitude and phase of the rotation speed fluctuation is performed. Determining the amplitude or phase of the rotational speed fluctuation in one rotation period of the controlled rotating body based on the measurement result, and determining the rotational speed fluctuation used for controlling the rotational drive source based on the amplitude or phase. The step of correcting the amplitude and the phase is executed by a computer.
The invention according to claim 44 detects the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational driving source that generates the rotational driving force transmitted to the controlled rotating body, and based on the detection result, the rotational driving source. 44. A recording medium on which a program used by a computer constituting a rotating body drive control device that controls the rotation of the controlled object rotating body is recorded, the program being any one of claims 41 to 43 . It is characterized by being a program.

When the rotational speed fluctuation of the rotating object to be controlled is mainly the rotational speed fluctuation of one rotation cycle, the inventors have determined the rotational speed fluctuation of the rotating object to be controlled using the amplitude and phase of the sine wave as unknown parameters. We paid attention to the point that it can be expressed by relatively simple mathematical formulas. Then, by measuring the rotation time of the predetermined rotation angle of the rotating object to be controlled when the rotational drive source is controlled under different driving conditions, the amplitude and phase of the above formula can be determined from the simultaneous equations established for the above formula. I found it. If the amplitude and phase are determined, it is possible to specify the rotational speed fluctuation of one rotation period of the rotating body to be controlled, and to control the rotational drive source so that the rotational speed fluctuation does not occur. Based on such knowledge, in the present invention, the rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the rotation when the controlled object rotating body rotates the predetermined rotation angle during the control by each control pattern. Measure time. Based on the measurement results of these rotation times, the amplitude and phase of the rotational speed fluctuation in one rotation cycle of the controlled rotating body are calculated by performing arithmetic processing on the mathematical expression including the amplitude and phase of the sine wave as unknown parameters. Ask. By controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, it is possible to suppress the rotational speed fluctuation of one rotation cycle of the controlled object rotating body. The rotation drive source is controlled as follows, for example. Using the amplitude and phase of the rotational speed fluctuation in one rotation cycle of the rotation object to be controlled, the rotational control pattern for the rotational axis of the rotational drive source that reduces the rotational speed fluctuation is determined in advance. By controlling the rotation drive source according to the rotation control pattern determined in this way, the rotation speed fluctuation of one rotation cycle of the controlled object rotating body is suppressed.
In the case of using a conventional rotary encoder, the rotation time during which the rotating object to be controlled rotates by a minute rotation angle (for example, several degrees or less) is continuously measured, and the measured rotation time and the data of the minute rotation angle are used. The rotational speed fluctuation is calculated. Therefore, in order to obtain the rotational speed fluctuation of the rotating object to be controlled with high accuracy, it is necessary to use an expensive rotary encoder that can output a pulse every rotation of a minute rotational angle. On the other hand, in the present invention, it is only necessary to measure the rotation time for one predetermined rotation angle (for example, π [rad]) during one rotation of the rotating object to be controlled. Therefore, it is necessary to use the expensive rotary encoder. Absent.

According to the present invention, the amplitude and phase of the rotational speed fluctuation in one rotation period of the controlled object rotating body are obtained based on the measurement result of the rotation time when the controlled object rotating body rotates the predetermined rotation angle. By controlling the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, it is possible to suppress the rotational speed fluctuation of one rotation cycle of the controlled rotor due to the eccentricity of the drive transmission rotating body.
In addition, since the rotation time can be measured for one predetermined rotation angle during one rotation of the controlled object rotating body, there is an effect that it is not necessary to use a high-accuracy rotary encoder that causes a high cost. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of an image forming apparatus having a controlled object rotating body controlled by the rotation drive control method of the present invention will be described.
FIG. 2 is a schematic configuration diagram of the image forming apparatus according to the present embodiment. In this embodiment, as an example of an image forming apparatus, a color image forming apparatus including four sets of image forming units of four colors, that is, yellow (Y), magenta (M), cyan (C), and black (K). A color printer will be described. In FIG. 2, the printer control unit 11 performs overall control of the color image forming apparatus 10. The color image forming apparatus 10 is a tandem image forming apparatus in which four photosensitive drums 1a to 1d as latent image carriers are arranged at predetermined intervals. An electrostatic latent image for black is formed on the photosensitive drum 1a, an electrostatic latent image for cyan is formed on the photosensitive drum 1b, and an electrostatic latent image for magenta is formed on the photosensitive drum 1c. An electrostatic latent image for yellow is formed on the photosensitive drum 1d. Hereinafter, the subscripts a, b, c, and d attached to the reference numerals in FIG. 8 indicate black, cyan, magenta, and yellow, respectively.

  Each of the photosensitive drums 1a to 1d is rotationally driven by motors 6a to 6d as rotational drive sources. The first to fourth laser scanners 2a to 2d as exposure means perform exposure on the surface of each photosensitive drum uniformly charged by a charging means (not shown) in accordance with an image signal, whereby each photosensitive body is exposed. Electrostatic latent images are formed on the drums 1a to 1d. These charging means and the first to fourth laser scanners 2a to 2d constitute a latent image forming means. The black image forming unit includes a photosensitive drum 1a, a first laser scanner 2a, and the like. The cyan image forming unit includes a photosensitive drum 1b, a second laser scanner 2b, and the like. The magenta image forming unit includes a photosensitive drum 1c, a third laser scanner 2c, and the like. The yellow image forming unit includes a photosensitive drum 1d, a fourth laser scanner 2d, and the like.

  A conveyance belt 3 as an endless belt body that also serves as a transfer belt sequentially conveys a sheet as a transfer material (not shown) to each color image forming unit. The drive roller 4 as a drive rotator is connected to a drive means including a motor as a rotation drive source (not shown) and a gear as a drive transmission rotator, and drives the conveyor belt 3. The fixing device 5 melts and fixes the toner transferred to the paper.

  The image forming apparatus having the above configuration operates as follows. When data to be printed is sent to the color printer 10 from a computer (PC) or the like (not shown), the dot image is converted into video data. When the conversion to the video data is completed and printing is possible, paper is supplied from a paper cassette (not shown) onto the conveyor belt 3. The sheets are sequentially conveyed by the conveyance belt 3 to the image forming units for the respective colors. The image signals of the respective colors are sent to the laser scanners 2a to 2d in synchronization with the conveyance of the paper by the conveyance belt 3, and electrostatic latent images are formed on the photosensitive drums 1a to 1d. The electrostatic latent images on the photosensitive drums 1a to 1d are developed by a developing device (not shown) to become a toner image, and are transferred onto a sheet conveyed by the conveying belt 3 by a transfer unit (not shown). In the color printer 10 of FIG. 2, images are formed in the order of K (black), C (cyan), M (magenta), and Y (yellow), but images are formed in the order of Y, M, C, and K. You may comprise as follows. Thereafter, the sheet is separated from the conveyance belt 3, and the toner image is fixed on the sheet by heat by the fixing device 5 and discharged to the outside of the color printer 10.

Next, rotation drive control of the photosensitive drum of the color printer of this embodiment will be described. In the color printer shown in FIG. 2, a DC servo motor which is a DC brushless motor is used as the motors 6a to 6d for driving the photosensitive drums 1a to 1d of the respective colors. When each of the photosensitive drums 1a to 1d is driven by such motors 6a to 6d, a positional deviation in the sub-scanning direction occurs on the image due to the influence of the following factors (1) and (2).
(1) Motor rotation fluctuation due to torque ripple, etc. (2) Transmission drive system error due to gear accumulated pitch error, rotation shaft eccentricity, etc.

  Image misregistration due to these factors is not limited to the tandem type image forming apparatus as shown in FIG. 2, and a revolver type developing device is used to form a toner image of a plurality of colors using a single photosensitive drum, and the overlapping is performed. This also occurs in the image forming apparatus that outputs the image. Also in an image forming apparatus that forms a single-color image with a single photosensitive drum, the image misalignment occurs due to the influence of similar factors. However, at present, in a tandem type image forming apparatus that can output a color image at a high speed like the color printer shown in FIG. Color misregistration "), and image quality deterioration is noticeable.

Therefore, in the present embodiment, in order to prevent the positional deviation in the sub-scanning direction due to the influence of the factor shown in (1) above, the rotational angular displacement or rotational angular velocity of the rotational shafts (motor shafts) of the motors 6a to 6d is the first. This is detected by an MR sensor described later as a detecting means. The motors 6a to 6d are feedback-controlled based on the detection result of the rotary encoder. With this control, rotational fluctuations of the rotation shafts of the motors 6a to 6d are suppressed.
On the other hand, in order to prevent the positional deviation in the sub-scanning direction due to the influence of the factor shown in (2) above, the amplitude and phase of the rotational speed fluctuation of one rotation period of each of the photosensitive drums 1a to 1d is obtained in advance, and the rotational speed fluctuation is obtained. The motors 6a to 6d are controlled based on the amplitude and phase of the motor. The amplitude and phase of the rotational speed fluctuation in one rotation cycle of the photosensitive drums 1a to 1d used for this control are obtained without using an expensive rotary encoder as follows. In other words, the motor is controlled by two or more control patterns that cause the rotational speed fluctuation of one rotation period having different amplitudes or phases to occur on the photosensitive drum, and the photosensitive drum is rotated at the predetermined rotational angle during the control by each control pattern. Measure the rotation time when rotating. Then, the amplitude and phase of the rotational speed fluctuation in one rotation period of the photosensitive drum are obtained based on the measurement result of each rotation time.

Next, the rotational drive control of the motors 6a to 6d for driving the photosensitive drums 1a to 1d will be described in detail.
FIG. 3 is a block diagram illustrating the configuration of the control system of the color printer 10 of the present embodiment. The printer control unit 11 includes a CPU 11a, a RAM 11b, a ROM 11c, and the like. The printer control unit 11 performs overall control of the color printer 10 by the CPU 11a executing a control program stored in the ROM 11c, and controls each unit in the color printer 10 as described below. The power supply unit 12 supplies power to each unit in the color printer 10. The sensors 13 detect various situations, operation states, and the like of each unit in the color printer 10. The motor control unit 14 as a rotating body drive control device controls motors 15 including motors (not shown) that drive the motors 6a to 6d and the conveyor belt 3 shown in FIG. To do. The motors 15 are power sources for various parts in the color printer 10. The motors 15 include an encoder necessary for control, a time variation detector within a certain angle, or the like. The display unit 16 notifies the user of the operation status of the color printer 10 and the like. The communication controller unit 17 performs communication between the color printer 10 and the host computer 18. The host computer 18 transfers data to be printed to the color printer 10.

  FIG. 4 is a block diagram for explaining the rotational drive mechanism of the motors 6a to 6d shown in FIG. In addition, the same code | symbol is attached | subjected to the same thing as FIG. Each color image forming unit includes a rotation transmission mechanism shown in FIG. In FIG. 4, the photosensitive drums 1 a, 1 b, 1 c, and 1 d are displayed as the photosensitive drum 1, and the motors 6 a, 6 b, 6 c, and 6 d are displayed as the motor 40. In FIG. 3, a configuration using a DC brushless motor as the motor 40 is illustrated. The photosensitive drum 1 includes a motor 40, a gear 46 as a drive transmission rotating body fixed to the rotation shaft (drive shaft) of the motor 40, and a drive transmission rotation body fixed to the rotation shaft of the photosensitive drum 1. It is driven by a gear 47. The gear reduction ratio is, for example, 1:20.

Here, the reason why the gear train of the rotational drive mechanism is made one stage is to reduce the number of parts and reduce the cost, and to reduce the cause of transmission error due to tooth profile error and eccentricity by using two gears. . Further, when a high reduction ratio is set by using the single-stage reduction mechanism, the gear 47 on the rotating shaft (output shaft) of the photosensitive drum 1 inevitably has a large diameter gear larger than the diameter of the photosensitive drum 1. Become. When the large-diameter gear 47 larger than the diameter of the photosensitive drum 1 is used as described above, the single pitch error of the large-diameter gear 47 converted on the photosensitive drum 1 is reduced, and print density unevenness (banding) in the sub-scanning direction is reduced. There is also an effect of reducing the influence of.
The reduction ratio is determined from a speed region in which high efficiency and high rotation accuracy can be obtained in the target speed of the photosensitive drum 1 and the DC motor characteristics.

  Further, the rotation axis of the photosensitive drum 1 includes a second rotation comprising a predetermined angle rotation time variation detector 50 for detecting a time for which the rotation axis rotates a predetermined angle, and a detection device 51 for detecting the passage thereof. Photosensitive drum shaft rotation detecting means is provided as a detecting means.

A DSP (Digital Signal Processor) 20 performs phase switching control based on a rotor position signal from a DC brushless motor 40, and motor start / stop control based on a control signal from the printer control unit 11. The designated speed information and the output of the speed detector are compared, speed control is executed based on the comparison result, and rotation unevenness control described below is performed.
The driver 30 outputs a predetermined drive current to the motor 40. The MR sensor 41 detects the rotational angular velocity (or rotational angle) of the motor. The hall element 42 detects the rotor position.

  FIG. 5 is a block diagram illustrating a control configuration of the DSP 20 shown in FIG. The DSP 20 includes a program controller 21 and an arithmetic unit 22. The arithmetic unit 22 includes a MAC 22a, an ALU 22b that performs addition / subtraction and logical operations, and the like. The DSP 20 includes a data memory 23a, a program memory 23b, a data memory bus 24a, a program memory bus 24b, a serial port 25, a timer unit 26, and an I / O port 27. As described above, the DSP 20 shown in FIG. 4 has a MAC that separates a memory for data and a program, separates a bus into a data bus and a program bus, and performs multiplication and addition in one machine cycle. , Enabling high-speed calculations.

FIG. 6 is an explanatory diagram showing detailed configurations of the DSP 20, the driver 30, and the motor 40 shown in FIG. Hereinafter, the configuration and operation thereof will be described.
In FIG. 6, the DC brushless motor 40 has a coil 43 and a rotor 44 that are U-phase, V-, and W-phase star-connected. Further, as the position detection unit of the rotor 44, three Hall elements 42 for detecting the magnetic poles of the rotor 44 are provided, and their output terminals are connected to the DSP 20. Further, a rotation speed detection unit (speed information detection unit) including a magnetic pattern 45 magnetized on the circumference of the rotor 44 and the MR sensor 41 is provided, and an output terminal thereof is connected to the DSP 20. The driver 30 that drives the DC brushless motor includes three high-side transistors 31 and three low-side transistors 32, and is connected to U, V, and W of the coil 43, respectively. The DSP 20 specifies the position of the rotor 44 based on the rotor position signals HU to HW generated by the hall element 42 and generates a phase switching signal. The phase switching signals UU to UW and LU to LW control the on / off of the transistors 31 and 32 of the driver 30 and rotate the rotor 44 by sequentially switching the phases to be excited. Further, the DSP 20 compares the rotation speed target value with the rotation speed information detected by the rotation speed detection unit, and generates and outputs a PWM signal. The PWM signal is ANDed by the phase switching signals UU to UW and the AND gate 33, and the drive current is chopped to control the rotation speed of the motor 40.

  Here, in FIG. 4, the MR sensor 41 is used as means for detecting the rotational speed of the rotor 44 (motor shaft). However, when higher-precision motor shaft rotation control is required, a higher-resolution rotation detection means is required. Therefore, as shown in FIG. 7, a rotary encoder 48 matched to the rotational accuracy of the motor shaft may be attached on the same axis, and rotation control may be performed based on the output signal of the rotary encoder.

  In the rotation drive control device for the photosensitive drum 1 shown in FIGS. 4 to 6, when driven by feedback (FB) control by detecting the rotation speed of the motor shaft, the photosensitive drum rotation shaft is eccentric with the gear 46 and the gear 47. And uneven rotation due to accumulated tooth pitch error.

FIG. 8 shows the rotation irregularity of the photosensitive drum when the rotation control device mechanism for the photosensitive drum 1 shown in FIGS. 4 to 6 is feedback-controlled with 10 gears 46 and a motor rotation speed of 1200 rpm. It is a characteristic view which shows the time characteristic. FIG. 9 is a frequency characteristic diagram showing the frequency components.
As can be seen from FIGS. 8 and 9, the rotational fluctuation (unevenness of rotation) of the photosensitive drum rotating shaft is roughly three. The first rotation fluctuation is uneven rotation occurring at the gear meshing cycle. This is mainly due to backlash caused by the relationship between tooth single pitch error, load fluctuation, and moment of inertia. However, in the configuration of this drive mechanism, as described above, since the diameter of the gear 47 is larger than the diameter of the photosensitive drum, when converted on the photosensitive drum, that is, on the image, the fluctuation for a single tooth pitch is small and the influence is small. . The second rotation fluctuation is uneven rotation generated by one rotation of the motor. This is mainly due to the accumulated pitch error and eccentricity of the motor shaft gear 46 due to transmission errors. However, in the configuration of the present drive mechanism, the rotation period of the gear 46 of the motor shaft is a natural number of a half rotation period of the gear 47. For this reason, the optical writing position fluctuation and the transfer position fluctuation have the same phase, and the influence on the positional deviation of the transferred image can be suppressed. The third rotation fluctuation is uneven rotation generated by one rotation of the photosensitive drum. This is mainly due to a cumulative pitch error of the gear 47 and a transmission error due to eccentricity. In addition, when the shaft of the gear 47 and the photosensitive drum 1 shaft are connected by coupling, an error in the center position of the both shafts and the angle of deflection are one of the causes.

Next, a photosensitive drum shaft rotation detecting means as a second detecting means for detecting that the photosensitive drum rotates at a predetermined rotation angle by using the rotation driving control device for the photosensitive drum according to the present embodiment will be described.
FIGS. 10A and 10B are diagrams showing one example of the photosensitive drum shaft rotation detecting means constituted by using the rod-like member 501 as the predetermined angle rotation time fluctuation detecting body 50 and the detecting device 51 for detecting the passage thereof. It is explanatory drawing which shows a structural example. This rod-shaped member 501 has a central portion in the longitudinal direction attached to the rotating shaft 1 ′ of the photosensitive drum, and has a detected portion at an end in the longitudinal direction. The detection device 51 is arranged to detect the passage of the detected portion at the end of the rod-shaped member 501. The photosensitive drum shaft rotation detection means in FIG. 10A is a configuration example in which one detection device 51 is provided. The photosensitive drum shaft rotation detection means in FIG. 10B is a configuration example in which two detection devices 51 are provided so that the detected portions at both ends of the rod-like member 501 can be detected simultaneously.

FIGS. 11A and 11B respectively show photosensitive drums configured by using plate-like members 502 and 503 having blade portions 502a and 503a formed by cutting out a part of a disc, and the detection device 51. It is explanatory drawing which shows the example of 1 structure of a shaft rotation detection means. These plate-like members 502 and 503 have a central portion attached to the rotation shaft 1 ′ of the photosensitive drum and have an edge-shaped detected portion at a part in the rotational direction at a position away from the central portion. A plate-like member 502 in FIG. 11A is an example of a plate-like member having a half-moon shaped blade portion 502a having an angle of 180 degrees formed by cutting out a disk. A plate-like member 503 in FIG. 11B is an example of a plate-like member having two fan-shaped blade portions 503a with an angle of 90 degrees formed by cutting out a disk.
Moreover, as shown to Fig.12 (a) thru | or (d), you may use the plate-shaped members 504-507 which cut out the disk and formed the fan-shaped blade | wing part 504a-507a. The plate-like member 504 in FIG. 12 (a) is obtained by cutting out a disk so as to leave a fan-shaped blade portion 504a having an opening angle of 120 degrees, and the plate-like member 505 in FIG. The disk is cut out so as to leave the fan-shaped blade portion 505a. FIGS. 12C and 12D are cut out so as to leave two fan-shaped blade portions 506a and 507a each having an opening angle of 60 degrees.
The detection device 51 in the case of using these plate-like members 502 to 507 is configured to detect the passage of the detected portion formed by the linear edge of the fan-shaped blade portion.

The rod-like member 501, the plate-like members 502 and 503, and the detection device 51 may be installed at either end in the axial direction of the rotating shaft 1 ′ of the photosensitive drum. Further, the rod-like member 501 and the plate-like members 502 to 507 may be fixed on the rotation shaft 1 ′ so as to rotate with respect to the rotation shaft 1 ′ of the photosensitive drum 1, and the rotation center thereof is the photosensitive drum. 1 may be fixed to the photosensitive drum main body side so as to rotate integrally with the photosensitive drum 1 so as to coincide with the rotation axis of the photosensitive drum 1.
Further, it is composed of a high light reflection part or a low light reflection part shaped like the blade part of the rod-like member 501 or the plate-like members 502 to 507 in FIGS. A detected mark may be formed. For example, when forming the detection mark of the low light reflection part, the rough surface is processed. Thus, when forming the detection mark of a high light reflection part or a low light reflection part, the problem of the error at the time of attachment like using the said rod-shaped member 501 and the plate-shaped members 502-507 can be reduced.

The detection device 51 shown in FIGS. 10 to 12 detects the passage of the detected portion at the end of the rod-shaped member 501 or the passage of the detected portion formed of the edge of the blade portion of the plate-shaped members 502 to 507. It is something to detect. The detection device 51 is a light transmission type detection device composed of a light emitting element and a light receiving element fixedly arranged so as to face each other at a position where the detected portion passes. Light blocking due to the end of the bar-shaped member 501 and the edge of the plate-shaped member passing between the light-emitting element and the light-receiving element is detected. Further, the detection device 51 detects the passage of the detected portion by irradiating light to the blade portions of the rod-like member 501 and the plate-like members 502 to 507 and detecting the light reflected from those members. It may be a light reflection type detection device.
The detection device 51 may be configured using a magnetic sensor in addition to the optical sensor. In this case, a magnetic body is fixed to the detected part of the bar-shaped member 501 and the detected parts of the plate-like members 502 to 507, and the detected part is allowed to pass using the magnetic field change when the detected part passes. Detect.
Further, in addition to using light shielding and magnetic field change due to the passage of the member to be detected, light is transmitted onto the disk member 508 as shown in FIGS. Optical marks 508a and 508b made of a light transmitting part or a light reflecting part that reflects light may be provided, or a magnetic mark may be provided. These marks may be directly provided on the photosensitive drum 1 which is a controlled object rotating body. Further, a semicircular cutout may be provided on the rotating shaft 1 ′ of the photosensitive drum 1, and light shielding and transmission by the cutout may be used.

Further, as a method for detecting the timing at which the detected portion passes, a method for detecting only at the rising portion or the falling portion of the output of the detection device 51 of FIG. 11B can be employed. In general, a phase error occurs in a circuit system or the like at the rising portion and the falling portion of the detection device 51, so that this error can be avoided by measuring at the same phase (either the rising portion or the falling portion). it can.
Also, as shown in FIG. 10B, when the two detection devices 51 are installed at positions 180 degrees apart from the rotation axis 1 ′, there are the following merits. That is, if the shaft center of the rod-shaped member 501 or the plate-shaped members 502 to 507 is eccentric, an error occurs in the half-rotation detection timing due to the eccentricity of the shaft center, but the error in the detection timing should be corrected. There is a merit that you can. As shown in FIG. 14, when the center of the rod-shaped member 501 or the plate-shaped members 502 to 507 is eccentrically attached to the center of the rotating shaft 1 ′ of the photosensitive drum 1, for example, the rod-shaped member and the plate The upper angle between 0 and 180 degrees is detected in a shorter time than the original half-rotation of the rotating shaft of the photosensitive drum, and the lower angle between 180 and 360 degrees is detected in a longer time. The The short time and the long time have symmetry, and the short time error and the long time error from the original time are substantially equal. Therefore, by averaging the detection times of the two detection devices 51, the influence of the eccentricity of the shaft center of the rotating shaft 1 ′ of the photosensitive drum, the rod-like member 501, and the plate-like members 502 to 507 is canceled, and the true A half rotation of the photosensitive drum 1 can be detected.

  Here, the rotational period of the gear 46 that transmits the rotational driving force from the motor 40 to the rotational shaft 1 ′ of the photosensitive drum 1 is the predetermined rotational angle detected by the photosensitive drum shaft rotation detecting means. It is a natural fraction of the rotation time, or a natural fraction of the time for the same part on the photosensitive drum 1 to move from the optical writing position to the transfer position to the paper on the conveying belt 3. That is, the rotation period of the gear 46 is 180 degrees (π rad) when the detection device 50 of FIG. 10 and FIG. 11 is used. It is a natural fraction of the period. As will be described later, this is a rod-like member provided on the same axis of the photosensitive drum 1 as the influence of the rotational transmission error to the photosensitive drum 1 due to the accumulated tooth pitch error and eccentricity over one cycle of the gear 46 is reduced. This is because the detection accuracy of the photosensitive drum shaft rotation detection means including the detection target 501 and the detection device 51 is increased. Further, when the optical writing position and the transfer position on the photosensitive drum 1 are arranged with an angle of 180 degrees in the rotation direction, the rotation period of the gear 46 is the half rotation period of the gear 47 coaxial with the photosensitive drum 1. It is a natural fraction of. With such a configuration, even if a rotation transmission error to the photosensitive drum 1 occurs due to the accumulated tooth pitch error or eccentricity over one cycle of the gear 46, the optical writing position fluctuation and the transfer position fluctuation are in phase, It is possible to suppress the influence on the displacement of the transferred image. Therefore, the default rotation angle is set to 180 degrees, the optical writing position and the transfer position on the photosensitive drum 1 are set to 180 degrees, and the rotation period of the gear 46 is a natural number of the half rotation period of the gear 47. If it is 1, the time fluctuation within the predetermined rotation angle that is not affected by the rotation period fluctuation of the gear 46 can be measured, and at the same time, the influence on the displacement of the transferred image can be suppressed.

Next, data processing and control operations in the photosensitive drum rotation drive control apparatus of the present embodiment will be described.
FIG. 1 is a flowchart showing a procedure of data processing and control operation for correcting and controlling the rotation fluctuation of one rotation cycle of the photosensitive drum in the rotation drive control apparatus according to the present embodiment. This data processing and control corresponds to the processing procedure executed by the program controller 21 based on the control program stored in the program memory 23b shown in FIG. In addition, (1)-(13) in a figure shows the step of each procedure. The program is activated by a control signal from the printer control unit 11.
First, before executing the drive control for correcting the rotation unevenness of one rotation of the photosensitive drum shaft, a correction sine reference signal for the drive control is calculated. This pre-operation is performed in the manufacturing process before shipping the product, and is further performed when the photosensitive drum is replaced. In addition, for example, when the fastening part slips over time or in the environment, it matches the user's usage status (timing when there is no print request) at every predetermined time, every number of sheets, during startup operation after turning on the power, etc. Do it.
The DSP 20 drives the motor 40 at a constant angular velocity by feedback control of the reference signal to be driven at the target rotational speed and the rotational speed signal of the MR sensor 41 or the rotary encoder 48 (step 1). It is determined from the rotational speed information whether the motor 40 has reached the target rotational speed (step 2). If the target rotational speed has not been reached, the process returns to step 2. On the other hand, if it is determined that the target rotational speed has been reached, the pulse output from the photosensitive drum shaft rotation detection means constituted by the rod-like member 501 that detects half rotation of the photosensitive drum 1, the detection device 51, etc. Is measured by the timer unit 26 shown in FIG. 5, and the time T1 of the measurement result is stored in the memory (step 3). At this time, in the case of the rod-shaped member 501 in FIG. 10, the DSP 20 always detects half rotation as to whether the half rotation from A to B or the half rotation from B to A shown in FIG. The output state of the photosensitive drum shaft rotation detecting means is observed by polling, and is determined by the rising (or falling) of the odd numbered pulse or the rising (or falling) of the even numbered pulse. Similarly in FIG. 10B, the determination is made based on whether the number is odd or even. The same applies to FIG. 11B. In FIG. 11A, a distinction is made according to the time interval of the output “1” level or the time interval of the “0” level. In FIG. 11 (b), if the opening angles of the two sectors are greatly different, it can be determined whether the number is an even number or an odd number based on the difference in time interval.

Further, as the interval measurement of the pulses output from the photosensitive drum shaft rotation detecting means, the output pulses of the rotary encoder 48 mounted on the motor shaft shown in FIG. 7 may be counted. In this case, the timer unit 26 is a pulse count unit. This is because the number of output pulses of the rotary encoder 48 is proportional to the speed and time of the motor shaft, so that if the speed is predetermined, the time can be measured by the output pulse count as in the timer unit measurement. As a result, even when the motor shaft rotation deviates from a predetermined speed due to load fluctuation or the like, it is possible to measure the photosensitive drum shaft predetermined angle rotation time from which the influence is removed. A method of measuring the rotation time T from the number of pulses in the case where the rotation speed of the predetermined motor shaft fluctuates like ΔωsinωoT, including the case where the rotation speed is constant, will be described below.
A predetermined rotational speed with a mean ωo and a fluctuation component of amplitude Δω can be expressed as ω = ωo + ΔωsinωoT. Here, the rotation angle θ of the photosensitive drum shaft is θ = ωoT− (Δω / ωo) {cosωoT−1}. When there is no fluctuation (Δω = 0), T = (1 / ωo) θ, and if the number of encoder rotation pulses is N, the one-pulse rotation angle Δθ is Δθ = 2π / N. If the encoder pulse count is n, the time T is T = (1 / ωo) θ = (1 / ωo) Δθ * n = {2π / (ωoN)} * n. When there is a change, (2π / N) * n = ωoT− (Δω / ωo) {cosωoT−1}. The relationship between the encoder pulse count and n and T may be tabulated based on this equation.

  Next, the reference component (speed control reference signal) of the target rotational speed used when driving with the rotation of the predetermined rotational angle is added to the fluctuation component (measurement sine for the preset period of one rotation of the photosensitive drum). The signal 40) is superposed with reference to the detection timing on the A or B side of the photosensitive drum shaft rotation detection means as a reference signal, and the motor 40 is driven by feedback control of the rotational speed signal of the MR sensor 41 or the rotary encoder 48. (Steps 4 and 5). As in step 3, the pulse interval is measured by the timer unit 26 and stored in the memory as time T2 (step 6). Here, based on the measured T1 and T2, the phase based on the amplitude of the rotational fluctuation component of one rotation period of the photosensitive drum shaft and the detection timing on the A or B side of the bar-shaped member 501 or the plate-shaped members 502 to 507 is calculated. (Step 7).

Here, the calculation of the amplitude and phase of the rotation fluctuation component in one rotation cycle of the photosensitive drum shaft is performed as follows.
First, when the motor shaft is driven at a constant angular velocity, rotation fluctuation occurs on the photosensitive drum shaft as shown in FIG. Paying attention to the rotation period of the photosensitive drum shaft among the fluctuation components, the amplitude of the fluctuation component is A, the initial phase based on the detection of the rod-shaped member 501 is α, and Asin (ωt + α), and the photosensitive drum shaft If the average angular velocity component of ω is ω (reduction ratio conversion from a constant motor shaft angular velocity), the rotational speed of the photosensitive drum 1 can be expressed by the following equation (1).

Here, since the photosensitive drum has made a half rotation (π radians rotation) at time T1, the following equations (2) and (3) are established.

The photosensitive drum half-rotation time T2 measured in steps (4) to (6) is set so that the measurement sine reference signal obtains the rotational speed fluctuation Msin (ωt) on the photosensitive drum shaft. If this is the case, the following formulas (4) and (5) hold as in the formula (2). At this time, when the rotational speed fluctuation is given to the photosensitive drum shaft, the home position (angle ωt = 2πN (where N is an integer)) of the fluctuation period is determined in advance by the rod-like member of FIG. 10 or the plate-like member of FIG. The time when the edge of the blade part passes the detection position by the detection device 51 is defined.

Equations (3) and (5) are transformed into equations (6) and (7), respectively.
However,

Here, since ω, T1, T2, E, and F are known constants, the amplitude A and the initial phase α of the fluctuation component of one rotation period of the photosensitive drum are obtained from the simultaneous equations of the equations (6) and (7). Can be requested. When Expressions (6) and (7) are modified and expressed as a matrix, the following expression is obtained.

When each matrix is set as B, X, and Y as described above, the matrix X is obtained by obtaining an inverse matrix of the matrix B as shown in the following equation.

Here, the obtained X is set as the following equation.

Therefore, the amplitude A and the initial phase α are obtained as in the following equations (10) and (11).

Thus, the amplitude A of the fluctuation component of one rotation cycle of the photosensitive drum shaft and the initial phase α based on the detection of the determined rod-shaped member or the edge portion of the rotating disk are obtained. From this A and α, the amplitude A is converted into the motor shaft rotational speed fluctuation amplitude in consideration of the reduction ratio, reversed to cancel the fluctuation, and delayed in phase by α relative to the reference output of the half-rotation detector. A sine wave reference signal is created (step 8). If this is used as a correction sine reference signal and superimposed on the speed control reference signal to drive the motor, fluctuations in the rotation period of the photosensitive drum 1 can be suppressed (steps 9 and 10).
Steps 1 to 8 are the preliminary operations described above. That is, the process up to step 8 is performed before the image output operation, and during the image output operation, fluctuations in the rotation cycle of the photosensitive drum 1 are suppressed by the operations of step 9 and step 10.
Here, the operations from step 11 to step 13 are operations for confirming whether or not fluctuations in the rotation cycle of the photosensitive drum 1 are suppressed. This operation may be omitted if the detection error and the drive accuracy error due to disturbance such as vibration during driving of the photosensitive drum are sufficiently small. Conversely, when there is a concern about detection errors such as disturbances, or when fluctuations are suppressed with high accuracy, this is an important step. You may carry out in the condition which can take adjustment time, such as the manufacturing process before market shipment. In step 11, the time for half rotation of the photosensitive drum is measured. Here, unlike the measurement in step 3 and step 4, not only one half rotation (rotation from A to B) but also the rotation cycle of both half rotations (including rotation from B to A) is measured. That is, the comparison is performed from the odd-numbered and even-numbered measurement values of the pulse period output by the detection device 51 (step 12).

In the present embodiment, when the fluctuation of the rotation period of the photosensitive drum 1 is appropriately suppressed, the odd-numbered and even-numbered cycles are equal. This periodic error is confirmed. If the error is within the specified range, the confirmation operation is terminated. However, if the periodic error is not specified, the amplitude and phase of the correction sine signal are adjusted, and the process is repeated from step 9. If the error does not fall within the specified range even after repeating this operation a plurality of times, the process returns to step 1 and the adjustment is performed again by calculating the amplitude A and the initial phase α of the fluctuation component of one rotation period of the photosensitive drum. In the present embodiment, the photosensitive drum is measured when the feedback rotation (FB) control of the constant angular velocity reference signal is measured and the sine reference signal for measurement is superimposed on the constant angular velocity and the FB control drive is performed. The half rotation period T2 was measured, and the amplitude A and the phase α of the fluctuation component of one rotation period of the photosensitive drum were calculated from these two data. Here, in order to calculate the amplitude A and the phase α with higher accuracy, a plurality of patterns of measurement sine reference signals having different amplitudes and / or phases are prepared, and the respective photosensitive sine reference signals are superimposed. The body drum half rotation period T2 ′ group may be measured. In that case, if the matrix is transformed in the same manner as the equations (6) and (7), the matrix becomes the following equation (12).

  By selecting any two rows of the matrix B and selecting the corresponding element of the column vector Y, the amplitude A and the phase α can be obtained in the same manner. If a plurality of combinations are obtained and the results are averaged, an accurate value can be obtained.

Even after the drive control is started, it is possible to measure the half rotation period of the photosensitive drum and update the amplitude and phase of the rotational fluctuation of the photosensitive drum to improve the accuracy. That is, the drive control signal is considered as a sine reference signal for measurement, the half rotation period of the photosensitive drum is measured, and the measurement result is substituted into the above equation (4) to calculate the amplitude or phase of the rotational fluctuation of the photosensitive drum. can do. Here, since only one equation substituted into the equation (4) is obtained, either the amplitude or the phase is calculated. For example, when the photosensitive drum is configured to be detachable for maintenance, etc., and is removable between the drive transmission gear unit and the photosensitive drum, if the phase changes in the fitted state of both, the phase Is calculated and corrected. Further, the fitting angle is configured to be restricted, but when the amount of eccentricity changes in the fitted state, the amplitude is calculated and corrected.
Even after drive control is started in this way, the half-cycle period of the photosensitive drum is measured, and the amplitude and phase of the rotational fluctuation of the photosensitive drum are updated to change the rotational fluctuation of the photosensitive drum over time and the environment. It can correspond to. In addition, the correction of the control data using the amplitude or phase data calculated here, that is, the update of the amplitude or phase data used for the control is performed in accordance with the degree of change in the rotational fluctuation of the photosensitive drum. preferable. For example, the rotation fluctuation amplitude and phase data used for the previous correction and the newly obtained amplitude and phase are weighted, and the average value of these is used to correct the amplitude and phase actually used for drive control. May be performed. In other words, by giving a large weighting coefficient to the newly obtained amplitude or phase data, the newly obtained amplitude or phase data is greatly reflected in the corrected amplitude or phase data, and the rotational fluctuation of the photosensitive drum It will be possible to respond to sudden changes in
Note that the process of measuring the half rotation period of the photosensitive drum and updating the amplitude and phase of the rotational fluctuation of the photosensitive drum can be applied to all of the embodiments described later even after the drive control described here is started. It is. For example, in the case of drive control of an endless belt body such as an intermediate transfer belt, the phase is corrected when slippage occurs between the drive roller and the belt body, and the thickness variation in the circumferential direction of the belt body changes due to temperature changes. When doing so, the amplitude is corrected.
In addition, here, the case where the rotation time when the photosensitive drum rotates by π radians as the default rotation angle, that is, the half rotation period is measured has been described. It can also be applied to.

  In the present embodiment, at the time of drive control when an image is output, a PWM drive control signal corresponding to the same amplitude and opposite phase (π phase shift or inversion) as the rotation fluctuation component of one rotation cycle of the photosensitive drum rotation shaft is generated. Then, the drive current is chopped based on the PWM signal to perform motor control. However, there is a case where the amplitude of the fluctuation component of one rotation cycle of the photosensitive drum rotating shaft is small and cannot be driven according to the PWM drive control signal, and the motor cannot be appropriately controlled. That is, there may be a case where a rotational fluctuation component of a small rotation period of the photosensitive drum exceeding the motor control range is detected. Alternatively, there is a case where the control error does not fall within the allowable range even if the feedback control is performed to correct the photosensitive drum 1 rotation cycle fluctuation component. In particular, this is likely to occur because the gain cannot be increased (the bandwidth of the control system cannot be increased) when the controlled rotor is not rigid. At this time, fluctuations in the rotation period of the photosensitive drum within the control error appear. In order to solve these problems, the embodiments described below are more preferable.

[Embodiment 2]
Next, an image forming apparatus according to another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. The image forming apparatus according to the present embodiment is different from the image forming apparatus according to the first embodiment in that phase alignment between the photosensitive drums is performed.
In this embodiment, in order to reduce the color misregistration caused by the rotation fluctuation of the rotation period of the photosensitive drum for each color, the rotation fluctuation phase data of each photosensitive drum detected in the first embodiment is used. . Using this rotation variation phase data, the drive motors are rotated independently so that a plurality of other photosensitive drums rotate with a predetermined phase difference with respect to one rotation cycle variation phase of a predetermined predetermined photosensitive drum. To drive. By independently rotating the drive motor in this manner, the rotational fluctuation phases of the photosensitive drums at the same pixel on the photosensitive drums of the respective colors are overlapped, color shift in the sub-scanning direction is reduced, and image quality deterioration is prevented. It becomes possible.

FIG. 15 is an explanatory diagram of phase alignment between the photosensitive drums in the case of the configuration of the image forming apparatus shown in FIG. As shown in FIG. 15, the four photosensitive drums are D0, D1, D2, and D3, and the rotation of the other three photosensitive drum driving systems is based on the photosensitive drum driving system of D0 at the end of the four photosensitive drums. Match the fluctuation phase. Here, it is assumed that the belt speed and the photosensitive drum circumferential speed are driven substantially equal. In order to superimpose the images affected by the rotational fluctuation formed by the four photosensitive drums on the conveying belt with the same fluctuation phase, the following control is performed. That is, if the arrows shown on the respective photosensitive drums in FIG. 15 indicate the rising zero cross phase of the rotation fluctuation, the zero cross rotation phase of D1 is advanced by a phase of (L / πφ) × 2π = 2L / φ [rad]. What is necessary is just to control so that it may rotate. Here, the distance between the photosensitive drums is L, and the diameter of the photosensitive drum is φ.
Similarly, the rotational phases of the photosensitive drums D2 and D3 are advanced by 4L / φ and 6L / φ [rad], respectively. When the zero cross phase of each photoconductor drum rotation fluctuation is driven with such a phase difference, the point of the arrow is also formed on the photosensitive drum D1 on the pixel transferred at the point of the exact arrow on the photosensitive drum D0. The pixels at the time when reaches the transfer position are superimposed. Similarly, D2 is delayed by one revolution and D3 is delayed by two revolutions, but the pixels when the arrow reaches the transfer position are overlapped. However, in the first embodiment, the zero-crossing phase of the rotation fluctuation to be obtained is the phase angle α from the rising point where the detection device 51 detects one (A) of the rod-shaped member (or rotating disk) 50 as shown in FIG. As obtained. When the phase angle obtained from each of the photoconductive drums D0 to D3 is set to α0 to α3, and the rotation variation phase of the other photoconductive drums is matched with reference to the detector rising at the photoconductive drum D0, the photoconductive drum D1 , D2, and D3 detector rising phase delays have a relationship as shown in the following equation (13).

Assuming that the angular velocity of each photoconductor drum is ω [rad / sec], the time difference between the output rise of the detection device on the photoconductor drum D0 and the output rise of the detection device on each photoconductor drum is expressed by the following equation (14). It becomes like this.

  FIG. 17 shows a timing chart of output pulses of the detection device 51 when the phase alignment correction operation of each photosensitive drum is completed. The other photosensitive drums D1, D2, and D3 are phase-matched with a time difference as shown in the above equation (14) with reference to the rising edge of the pulse detected at the A side shown in FIG. 16 by the detector of the photosensitive drum D0. Yes. As described above, in order to match the rotational phases of the photosensitive drums, the phase adjustment can be easily performed by performing the drive rising timing of the photosensitive drums with a time difference as shown in the equation (14). As described above, by adjusting the phase of the photosensitive drum one-cycle fluctuation when starting up the photosensitive drum driving unit, the time difference between the output pulses of the detection devices becomes the time difference as shown in FIG. However, when each photosensitive drum is driven independently, an error occurs in the time difference shown in the equation (14) due to the rising operation error between the motors. When there is an error in the time difference of the photosensitive drum one-cycle fluctuation phase as described above, the adjustment is performed by making the rotational speed of the motor faster or slower than the reference speed in a certain time according to the error amount. For example, the motor is controlled at a constant angular velocity with a reference signal for driving and controlling the photosensitive drum at a target angular velocity, and the output interval of the predetermined angular rotation time variation detector is measured.

  Further, the above-described photosensitive drum shaft rotation detecting means in FIG. 11B employs a method of detecting only at the rising or falling portion of the detector output. In general, a phase error occurs in the rising and falling parts of the detector output in the circuit system, etc., so this phase error can be avoided by measuring at the same phase (either the rising or falling part). it can. The detection device (edge detector) 51 in FIG. 11 is a light transmission type detection in which the light emitting element and the light receiving element are fixedly arranged so that the blade portions of the plate-like members 502 to 507 pass between the light emitting element and the light receiving element. It may be a device, or may be a reflection type detection device in which a light emitting element and a light receiving element are opposed to a detected part on one surface side of a blade part of the plate-like members 502 to 507. . Moreover, the blade | wing part of a rod-shaped member or a plate-shaped member may be formed with a magnetic body, and may be detected magnetically.

[Embodiment 3]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. The image forming apparatus according to the present embodiment is different from the image forming apparatus according to the first embodiment in that the opening angle between the light writing position on the photosensitive drum 1 and the transfer position is not 180 degrees.
In the image forming apparatus according to the first embodiment, the position between the optical writing position on the photosensitive drum as viewed from the rotation center of the photosensitive drum 1 and the transfer position to the transfer body (transfer paper, intermediate transfer drum, or intermediate transfer belt). The opening angle is 180 degrees. However, the configuration as in the first embodiment cannot be taken from the layout of the entire image forming apparatus, and the opening angle between the light writing position and the transfer position on the photosensitive drum 1 is not 180 degrees as in the present embodiment. There is a case.

FIG. 18 is an explanatory diagram showing the positional relationship between the optical writing position Pex on the photosensitive drum 1 and the transfer position Pt in the present embodiment. As shown in FIG. 18, the opening angle between the optical writing position Pex and the transfer position Pt as viewed from the rotation center C of the photosensitive drum 1 is an angle γ smaller than 180 degrees. The photosensitive drum shaft rotation detecting means having such a configuration includes plate-like members 504 to 507 having blade portions having the shapes shown in FIGS. 12A to 12D, and a high reflectance having a similar shape. A disk member having a portion and a low reflectance portion is suitable. The plate-like members 504 to 507 shown in FIG. 12 are selected to have blades with appropriate shapes depending on whether the rising part of the output signal of the detection device 51 is detected or the falling part is detected. In particular, when the plate-like members of FIGS. 12C and 12D are used, detection is performed at either the rising part or the falling part, and therefore the output waveforms of the rising part and the falling part are Detection error (phase error) due to the difference does not occur. Even when such a photosensitive drum shaft rotation detecting means is used, the steps of measuring the amplitude and phase of the rotational fluctuation in one rotation period of the photosensitive drum and the drive control method or the phase matching method between the photosensitive drums are implemented as described above. This is the same as in the first and second embodiments, and the same discussion can be made by assuming that “π” in the equations (2) and (4) is “γ”. The expressions (2) and (4) shown in the first embodiment are respectively the following expressions (15) and (16).

  Also in the present embodiment, as in the first embodiment, the rotation period of the gear 46 in FIGS. 4 and 7 is such that the eccentricity and accumulated pitch error do not affect the detection of the predetermined angle rotation time fluctuation. Is a natural number of a predetermined angular rotation period of the photosensitive drum shaft rotation detecting means shown in FIG. In addition, since the predetermined angle is an opening angle between the exposure position Pex and the transfer position Pt, the fluctuation of the gear 46 is the same as the position fluctuation phase in exposure and the position fluctuation phase in transfer. The influence on the positional deviation can be suppressed.

[Embodiment 4]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. The image forming apparatus according to the present embodiment is different from the image forming apparatuses according to the first to third embodiments in that two kinds of rotation cycle fluctuations are suppressed by a two-stage correction operation.
In the image forming apparatuses of the first to third embodiments, the exposure unit and the transfer unit are detected by detecting and controlling the rotational fluctuation of one rotation cycle of the large-diameter gear 47 installed on the rotation shaft 1 ′ of the photosensitive drum 1. The positional deviation of the image due to the speed fluctuation can be suppressed. Further, by rotating the photosensitive drum 1 at a constant speed, the speed difference between the photosensitive drum 1 and the transfer body at the time of transfer from the photosensitive drum 1 to the transfer body (transfer paper, intermediate transfer drum, intermediate transfer belt). Fluctuation can be reduced. As a result, it is possible to suppress the collapse of the pixels during transfer (thickening of the pixels).
In the image forming apparatus according to the first exemplary embodiment, the rotational period of the motor shaft gear 46 is set to a period that is a fraction of the natural number of times that the photosensitive drum 1 rotates the exposure and transfer position angle, thereby shifting the position of the transferred image. It has a configuration to suppress. However, although pixel expansion / contraction can be reduced, the photosensitive drum 1 has a rotational speed fluctuation of the motor shaft gear 46 due to the eccentricity of the motor shaft gear 46 and the accumulated tooth pitch error. Fluctuation has occurred. As a result, pixel collapse (pixel fattening) occurs, and the image is recognized as shading (banding). In particular, as in the configuration shown in the first embodiment, when the reduction ratio is 1:20, the diameter of the photosensitive drum 1 is 40 mm, and the transfer member conveyance linear velocity (= photosensitive drum peripheral speed) is 125 mm / s, the motor The period fluctuation of one rotation of the shaft gear 46 becomes banding with a pitch of 6.5 mm on the image, and is easily recognized visually. For this reason, detecting and controlling the fluctuation of one rotation period of the motor shaft gear 46 is very effective in realizing high image quality.

  Therefore, in this embodiment, not only one rotation cycle variation of the gear 47 on the rotation shaft 1 ′ of the photosensitive drum 1 but also one rotation cycle variation of other gears is detected, and control is performed based on the detection result. . The drive control method of this embodiment can be applied to a transfer belt drive roller, a transfer paper transport roller, and the like, and will be described together.

In the image forming apparatus according to the present embodiment, first, fluctuations in the rotation cycle of the photosensitive drum and the driving roller, which are control target rotating bodies, are removed by the same method as in the first embodiment. In this state, the phase and amplitude of the rotation cycle variation of another transmission mechanism such as a motor shaft gear are detected by a similar method. Correction control can be performed based on the detection result. That is, the rotation time of the second predetermined angle having an angle smaller than the rotation angle of the controlled object rotating body when the motor shaft is rotated once on the rotating shaft of the controlled object rotating body (photosensitive drum or driving roller). A bar-like member or a plate-like member for measuring is installed. Instead of installing these members, a mark for measuring the rotation time of the second predetermined angle may be provided at the end of the photosensitive drum 1. The detection device that detects the passage of these members and marks detects the amplitude and phase of one rotation period variation of the motor rotation shaft. The second predetermined angle is preferably set to a rotation angle at which the controlled object rotating body rotates when the motor shaft rotates by one half. When set in this way, the detection sensitivity is highest with respect to the phase and amplitude of the rotation cycle variation of other transmission mechanisms such as motor shaft gears.
As described above, after correcting and removing the rotation cycle variation of the photosensitive drum or drive roller that is the controlled rotor, the phase and amplitude of the rotation cycle variation of other transmission mechanisms such as motor shaft gears are detected. Control to correct.

FIGS. 19A to 19D are explanatory views showing a configuration example of a plate-like member 509 for detecting both the rotation fluctuation of one rotation cycle of the photosensitive drum 1 and the rotation fluctuation of one rotation cycle of the motor shaft. It is. The plate-like member 509 is formed with a fan-shaped blade portion 509a by notching a part of the disk member in the same manner as the plate-like members 502 to 507 shown in FIGS. The thick line in the figure indicates the edge to be detected.
Instead of the plate member 509, a disk member provided with an optical mark or a magnetic mark having the same shape as the blade 509a on the surface may be used. Moreover, you may provide the same mark in the axial direction end surface of a control object rotary body.

  19A to 19D, three types of angles γ, β1, and β2 between edges extending in the radial direction of each blade portion 509a are set as follows. Here, the angle γ is an angle for detecting the amplitude and phase of one rotation fluctuation of the controlled object rotating body as described in the first and third embodiments, and the controlled object rotating body is a photosensitive drum. In some cases, the angle between the exposure position and the transfer position may be adjusted. The angle β1 is an angle for detecting the amplitude and phase of one rotation fluctuation of the motor shaft. This angle β1 may be any angle as long as it is equal to or less than the rotation angle of the control target rotor for one rotation of the motor shaft, but the rotation angle of the control target rotor when the motor shaft rotates by one half. When set to, detection sensitivity is highest. The angle β2 is also an angle set for the same purpose as the angle β1.

In the plate-like members of FIGS. 19A to 19D, since only one of β1 and β2 has to be set as the rotation angle for detecting the motor shaft period fluctuation, one of the angles β1 and β2 is the motor. You may change into the angle used for uses other than an axial period fluctuation | variation detection. When the angles β1 and β2 are made different from each other in this way, it can be used to determine which rotation angle is detected. That is, since the rotation speed does not change greatly, it is possible to determine which angle is measured based on the measurement result of the rotation time of the angle β1 or β2. That is, by measuring the passage time of the fan-shaped blade portion, it is possible to determine which blade portion of the two blade portions is detected in each plate-like member. And the fluctuation | variation of a motor shaft 1 rotation period is detectable by the fluctuation | variation of the rotation time for which a plate-shaped member rotates only the center angle of a fan-shaped blade | wing part.
Moreover, in this embodiment, the shape of the to-be-detected part which passes the detection position by the detection apparatus 51 does not need to be a fan shape. For example, as shown in FIGS. 13 (a) and 13 (b), optical marks 508a, 508b and magnetic marks made of a rectangular light transmitting portion and light reflecting portion provided on the disk member 508 may be used. . These marks may be formed on the end surface of a photosensitive drum or a driving roller which is a rotating body to be controlled.

Here, the rotation period of the motor shaft (one rotation time) is the rotation object to be controlled so that the phase relationship between one rotation period of the motor shaft and the rotation period of the rotation object to be controlled (photosensitive drum or drive roller) is constant. Is set to be a natural number of the rotation period. That is, in the case of FIG. 19 (a), β1 × N = 2π or β1 × N = 2π (N: natural number) is set. With this setting, when the cycle variation of the motor shaft is detected by a plurality of operations, the cycle variation of the motor phase can always be detected with the same phase variation cycle, so that the cycle variation of the motor shaft can be accurately detected and used for control.
It should be noted that instead of the relationship of β1 × N = 2π or β1 × N = 2π (N: natural number), the relationship of β1 × N = 2πM or β1 × N = 2πM (N, M: natural number) is satisfied. You may comprise as follows. In this case, it is only necessary to generate the reference signal for detecting the fluctuation period of the motor shaft and correcting the fluctuation based on the reference rotational angle position for each M rotations of the rotating body to be controlled. In this case, it is necessary to always measure the time lag for each M rotation for detecting the reference position. Therefore, when starting up again after turning off the power supply, it is necessary to start from the period fluctuation detection operation.

FIGS. 20A to 20C show the detection time of the edge of the blade portion even when the plate-like member having the blade portion (or detection mark) is eccentric, and the rotation time of the predetermined rotation angle. 2 shows a configuration example of a photosensitive drum shaft rotation detection unit configured to measure the temperature accurately. The plate-like member 510 of this configuration example includes two sets of two fan-shaped blade portions arranged so that the edge (thick line) to be detected is positioned at a position shifted from each other by π [rad]. Then, in order to know which edge is detected, one blade portion formed in the two blade portions 510a, 510a′510b, 510b ′ so that the central angle is different from the other blade portions (in FIG. 20). The blade portion indicated by reference numeral 510b) is used as a blade portion for edge identification. By knowing the rotation time and order of the central angles of these blade portions, it is possible to determine which edge is being detected.
First, in order to detect the rotation fluctuation of one rotation period of the photosensitive drum, the method described so far is used by two edges corresponding to the exposure and transfer sandwich angles in one pair of blade portions 510a and 510a ′. Then, the amplitude and phase of the rotation fluctuation in one rotation cycle are calculated. Further, the amplitude and phase of the rotation fluctuation in one rotation cycle are calculated from two edges corresponding to the exposure and transfer sandwich angles in the other pair of blade portions 510b and 510b ′. By calculating the average values of these calculated amplitudes and phases and using them in the control, it is possible to reduce the detection error of the edge of the blade and accurately measure the rotation time of the predetermined rotation angle. The average value of the amplitude and phase is calculated as follows, for example. That is, a vector sum of two vectors composed of two detected amplitudes and phase angles is calculated, and ½ of the magnitude of the vector sum is used as an average value of the amplitudes. Further, the phase of the vector sum is set as the average value of the phases.
Next, based on the calculated average values of the amplitude and phase, rotation control is performed so as to remove the photosensitive drum cycle fluctuation, and the rotation fluctuation of one rotation cycle of the motor shaft is detected as follows. First, in order to detect the rotation cycle fluctuation of the motor shaft, one set having a central angle smaller than the photosensitive drum rotational angle (photosensitive drum rotational angle corresponding to a half rotation of the motor shaft for increasing detection sensitivity). Two edges of the blade portion 510a are detected. Thus, by detecting the two edges of the blade portion 510a and measuring the rotation time of the central angle of the blade portion 510a, the amplitude and phase of the motor shaft rotation period fluctuation are calculated in the same manner as described above. The blade portion 510a is at a position that is out of phase by π [rad], and is smaller than the rotation angle of the photosensitive drum (a photosensitive drum corresponding to a half rotation of the motor shaft in order to increase detection sensitivity). Two edges are detected for the fan-shaped blade portion 510a ′ having a rotation angle. In this way, by detecting the two edges of the blade portion 510a 'and measuring the rotation time of the central angle of the blade portion 510a', the amplitude and phase of the motor shaft rotation period variation are calculated in the same manner as described above. To do. By using the average values of the calculated amplitude and phase, the influence of the eccentricity of the plate-shaped member having the fan-shaped blade portion and the mark can be reduced.
Next, in order to eliminate motor shaft rotation fluctuation, control is performed by adding a sinusoidal reference signal whose phase is shifted by π from the average value of the amplitude and phase of the calculated motor shaft rotation period fluctuation to the motor control reference signal. To do. Here, the rotation cycle of the motor shaft (= one rotation time) is the rotation of the control target so that the phase relationship between the rotation cycle of the motor shaft and the rotation cycle of the control target rotor (photosensitive drum or drive roller) is constant. It is set to be a natural number of the body rotation period. With this setting, it is always possible to detect the fluctuation of the motor shaft cycle by multiple operations, so that the detection error of the blade edge can be reduced and the rotation time of the predetermined rotation angle can be accurately determined. It can be measured and controlled.

FIG. 21 shows a configuration example of a photosensitive drum shaft rotation detecting unit suitable for driving a rotating body to be controlled other than the photosensitive drum (for example, a driving roller of the intermediate transfer belt) from the motor at a one-step speed reduction. Also in this configuration example, even if the plate-like member 511 having the blade portion (or detection mark) is eccentric, the edge detection error of the blade portion can be reduced and the rotation time of the predetermined rotation angle can be accurately measured. .
As shown in FIG. 21, the plate-like member 511 of this configuration example has two fan-shaped blade portions 211a and 211a arranged so that the edge (thick line) to be detected is located at a position shifted from each other by π [rad]. 'And a blade portion 211b for edge identification having a large central angle. The rotational fluctuation of one rotation cycle of the rotating body to be controlled (for example, the driving roller of the intermediate transfer belt) is detected by one rotation angle of the edge of the thick line portion of one blade portion 211a among the one set of blade portions. Furthermore, it detects by the rotation angle of the edge which shifted pi of the other thick line part. Thus, the average value is obtained by the above method. Further, the central angles of the fan-shaped blade portions 511a and 511a ′ facing each other are for detecting a motor shaft cycle variation. The fan-shaped blade portion 511b that is not for detecting the motor shaft cycle fluctuation is provided so that it can be seen which edge is detected. Here, the rotation cycle (one rotation time) of the motor shaft is the rotation cycle (one rotation time) of the control target rotor so that the phase relationship between the rotation cycle of the motor shaft and the rotation cycle of the control target rotor is constant. It is preferable to set so that it becomes 1 / natural number. In this case, in FIG. 21, a relation of β × N = 2π (N: natural number) is established.

  Further, a notch portion may be provided in one of two blade portions (for example, blade portions 510a and 510a ′ in FIG. 20) separated by an angle π [radian], or a mark member may be newly added. . As a result, one of the detected parts (edge parts) in each blade part can be distinguished from the detected part in the other blade part, and one rotation of the plate-like member as the detected object can be made. The reference position can be determined. For example, the timing at which the edge of one of the blades is detected can be used as the reference timing for the drive control signal or the reference timing for phase alignment of the photosensitive drum.

[Embodiment 5]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. The image forming apparatus according to the present embodiment uses the speed reduction mechanism that uses a planetary gear instead of a gear train as the speed reduction mechanism in the drive transmission unit from the motor to the rotating object to be controlled (photosensitive drum or belt drive roller). Different from the image forming apparatus of the first embodiment.

  FIG. 22 shows a configuration example of the planetary gear reduction mechanism used in the image forming apparatus of the present embodiment. This planetary gear reduction mechanism is configured such that the planetary gears 103 and 104 mesh with the output gear 106 and the fixed gear 105 arranged on the same axis and having different numbers of teeth. At least one of the fixed gear 105 and the output gear 106 is a shift gear so that the meshing pitch circles of the fixed gear 105 and the output gear 106 are the same. When the input shaft 101 rotates, the planetary gears 103 and 104 rotate in a planetary manner as shown in FIG. 23 while meshing with the fixed gear 105 and the output gear 106. As a result, the output gear 106 rotates, the rotational force is transmitted to the output shaft 102, and the drive target rotates at a predetermined rotational speed. The reduction ratio at this time is obtained based on the difference in the number of teeth of the output gear 106 and the fixed gear 105, and does not depend on the number of teeth of the planetary gears 103 and 104. Therefore, when a reduction ratio of 1/20 is obtained, for example, the number of teeth of the output gear 106 may be 40 and the number of teeth of the fixed gear 105 may be 38. In the present embodiment, in the configuration of FIG. 22, for example, a photosensitive drum shaft (not shown) is shared with the output shaft 102, or the photosensitive drum shaft and the output shaft 102 are coupled by coupling. A drive motor shaft (not shown) is shared with the input shaft 101, or the drive motor shaft and the input shaft 101 are coupled by coupling.

  By using the planetary gear reduction mechanism configured as described above, a small reduction ratio and a high reduction ratio can be obtained. In addition, since the meshing cycle between the planetary gears 103 and 104, the output gear 106, and the fixed gear 105 is a high frequency, there is an advantage that unevenness in image density of the gear meshing cycle called banding is not noticeable. However, the eccentricity of the fixed gear 105 and the accumulated pitch error of the teeth, and the eccentricity of the output gear 106 and the accumulated pitch error of the teeth become the fluctuation factors of the output shaft 1 rotation cycle, and the rotation fluctuation tends to be larger than that of the gear train. Therefore, in the present embodiment, as described in the first embodiment, a rotary encoder is installed on the DC servo motor or the motor shaft, and a drive source having a configuration capable of feedback control of the motor shaft rotation is used. Then, the above-described rod-shaped member or plate-shaped member (rotary disk) is installed in a form integrated with the photosensitive drum shaft or the photosensitive drum, and the fluctuation of the predetermined rotation time of the photosensitive drum is detected. With such a configuration, it is possible to drive the photosensitive drum with high accuracy. Even in this case, the plate-like member (rotary disc) that detects the time fluctuation within the predetermined angle has a different central angle so that the periodic fluctuation of the input shaft 101, the planetary gears 102 and 103, and the photosensitive drum shaft can be detected. A plurality of fans or marks are provided. The detection error can be suppressed by setting the rotation cycle of the input shaft 101 or the rotation cycle of the planetary gears 102 and 103 to a natural number of a constant angle rotation cycle of the photosensitive drum shaft. Further, when the fixed angle is an angle formed by the exposure position Pex on the photosensitive drum and the transfer position Pt, it is possible to reduce image expansion and contraction due to rotational fluctuations of the input shaft 101 and the planetary gears 102 and 103. Even when there are a plurality of transmission mechanisms (gears or timing belts) having a periodic variation between the motor shaft and the controlled object rotating body (photosensitive drum or belt driving roller) as in this embodiment, the rotating shaft of the controlled object rotating body A plate-like member (rotary disk) or mark provided on the same axis or on the end surface to be controlled is formed so as to detect the respective rotation period fluctuations. Then, it can be predicted from the above explanation that the periodic fluctuation can be corrected if the cyclic fluctuation correction sequence is performed in the descending order of the cyclic fluctuation. However, in this case, the rotation cycle of the motor shaft, the rotation cycle of the plurality of transmission mechanisms, and the rotation cycle of the rotating body to be controlled are set to a natural number ratio. In this way, the phase relationship is always constant and the fluctuation period detection accuracy can be maintained.

[Embodiment 6]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. The image forming apparatus according to the present embodiment uses a speed reduction mechanism that uses friction transmission and traction transmission without using a gear as a speed reduction mechanism in a drive transmission unit from a motor to a rotating object to be controlled (photosensitive drum or belt drive roller). This is different from the image forming apparatus of the first embodiment.

  FIG. 24A is a front cross-sectional view showing a configuration example of a planetary roller speed reducer 35C using traction transmission used in the image forming apparatus of the present embodiment. The planetary roller speed reducer 35C is a known speed reducer, and basically includes a sun roller, a planetary roller that rotates in contact with the circumferential surface of the sun roller, and a carrier that rotatably supports the planetary roller. is there. When the sun roller rotates, the planetary roller transmits the rotation of the sun roller to the carrier by friction driving to rotate the carrier. A desired reduction ratio (speed increase ratio) can be obtained by adjusting the arrangement of the three elements of the sun roller, the planetary roller, and the carrier and the circumferential length of each roller.

FIG. 24B is a side cross-sectional view specifically showing the configuration of the planetary roller speed reducer 35C in the present embodiment, and is a side cross-sectional view in the direction of the arrow BB shown in FIG. Planetary rollers 352C, 353C, and 354C are disposed around a motor shaft 341C corresponding to the sun roller. Each of these planetary rollers 352C to 354C is pivotally supported by shaft bodies 3521C, 3531C, and 3541C projecting from one end surface of the carrier 355C, and the circumferential surface is inscribed in the housing 357C. When the drive motor 40 shown in FIG. 6 of the first embodiment rotates, the planetary rollers 352C to 354C roll around the motor shaft 341C while being guided by the inner peripheral surface of the housing 357C, and the planetary rollers 352C to 354C are rotated. The carrier 355C that supports the shaft is rotated at a lower speed than the motor shaft 341C. The planetary rollers 352C to 354C are formed by covering the peripheral surface of a metal shaft center with an elastic member. Although it is made hard to produce a slip by an elastic member, a slip cannot be eliminated completely. An output shaft 356C for transmitting the rotation of the carrier 355C is provided on one end surface of the carrier 355C.
The motor shaft 341C, the planetary rollers 352C to 354C, and the carrier 355C are housed in housings 357C and 358C joined by screws 3581C, 3582C, and 3583C. The housing 357C is fixed inside the copying machine by a support member (not shown). Has been. By using such a planetary roller speed reduction mechanism 35C, the rotation is transmitted by contact with the roller peripheral surface, so that the power is transmitted smoothly and no vibration of a high frequency component occurs when a gear such as a speed reduction gear is used. . However, there is a possibility that slip occurs on the contact surface between the rollers, and in this case, the rotation unevenness of the low frequency component becomes large. Further, the rotation unevenness of one rotation of the output shaft occurs due to the roundness of the inner peripheral surface of the housing 357C. Therefore, in the present embodiment, as described in the first embodiment, a drive source having a configuration in which a rotary encoder is installed on the DC servo motor or the motor shaft and the motor shaft rotation can be feedback controlled is used. Then, the above-described rod-shaped member or plate-shaped member (rotary disk) is installed in a form integrated with the photosensitive drum shaft or the photosensitive drum, and the fluctuation of the predetermined rotation time of the photosensitive drum is detected. At this time, first, the period of one rotation of the photosensitive drum is measured at one edge of the rod-shaped member or plate-shaped member (rotary disk), and it is confirmed whether or not the target reference rotational speed of the photosensitive drum 1 has been reached. It is possible to correct the slip component. After performing this operation, correction drive control or phase adjustment of the rotation fluctuation of one rotation period of the photosensitive drum as described in the first embodiment, the second embodiment, or the third embodiment is performed. Thereby, it is possible to drive the photosensitive drum with high accuracy.

FIG. 25 shows a configuration example of a speed reducer using a flat belt. This speed reducer is decelerated by the diameter ratio of the small pulley 302 on the input shaft 300 coaxial with the rotating shaft of the drive source (brushless DC servo motor) 40 provided on the frame 400 and the large pulley 303 on the output shaft 304. It is a known speed reducer. In this configuration example, stainless steel is used as the material of the belt 301 in order to perform transmission with higher accuracy. Further, the output shaft 304 and the rotating shaft 1 ′ of the photosensitive drum 1 are connected by a coupling 305.
The transmission of rotation in the reduction gear is due to the contact between the peripheral surfaces of the pulleys 302 and 303 and the flat belt 301, so that power transmission is performed smoothly and no vibration of high frequency components occurs when gears are used. However, there is a possibility that slip occurs between the contact surfaces of the pulleys 302 and 303 and the flat belt 301. Further, in terms of component accuracy, the large pulley 303 tends to have a larger amount of eccentricity than the small pulley 302, and a transmission error due to the eccentricity occurs, resulting in uneven rotation of the output shaft 304 in one rotation cycle. Therefore, in the present embodiment, as described in the first embodiment, a drive source having a configuration in which a rotary encoder is installed on the DC servo motor or the motor shaft and feedback control of the motor shaft rotation is used. Then, the above-described rod-shaped member or plate-shaped member (rotary disk) is installed in a form integrated with the photosensitive drum shaft or the photosensitive drum, and the fluctuation of the predetermined rotation time of the photosensitive drum 1 is detected. At this time, first, the period of one rotation of the photosensitive drum is measured at one edge of the rod-like member or plate-like member (rotary disc), and it is confirmed whether or not the target reference rotational speed of the photosensitive drum has been reached. It is possible to correct the slip component. After this operation is performed, correction driving control or phase matching of the rotation fluctuation of one rotation period of the photosensitive drum as described in the first embodiment, the second embodiment, or the third embodiment is performed. Thereby, it is possible to drive the photosensitive drum with high accuracy.
Further, even when the correction drive control for correcting the rotation fluctuation is executed, the rotation period of the photosensitive drum 1 is always measured at one edge of the rod-shaped member or plate-shaped member (rotary disk), and the photosensitive member is measured. It is confirmed whether the target reference rotation speed of the drum 1 has been reached, and the steady slip component is corrected. If the correction reference signal is generated in synchronism with the timing at which the edge that is the home position of the bar-like member or plate-like member (rotary disc) is detected, the effect of slipping does not accumulate.
In the present embodiment as well, the detection error can be suppressed by setting the rotation period of the input shaft 300 to a natural number of the predetermined angle rotation period of the photosensitive drum shaft. Further, when the certain angle is an angle formed by the exposure position Pex on the photosensitive drum 1 and the transfer position Pt, the expansion and contraction of the pixels due to the rotational fluctuation of the input shaft 300 can be reduced. When the control target rotator is a driving roller that drives the intermediate transfer belt as in the image forming apparatus shown in FIG. 27, the intermediate transfer belt between the transfer units including the secondary transfer unit is set to one rotation time of the drive roller. It is preferable to set the natural number of the passage time. Further, the plate-like member (rotary disk) or mark as shown in FIG. 21 is provided on the drive roller shaft or the end surface of the drive roller. Further, the time for rotating the central angle of the fan-shaped blade portion for detecting the periodic fluctuation of the motor shaft is also set to a natural number of the intermediate transfer belt passing time between the transfer portions including the secondary transfer portion. When configured in this way, it is possible to reduce image color misregistration and expansion / contraction. Here, the phase relationship between the rotation cycle of the motor shaft and the rotation cycle of the drive roller is set so that the rotation cycle (one rotation time) of the motor shaft is a natural number of the rotation cycle of the drive roller. When a configuration in which a plate-like member (rotary disk) or a mark as shown in FIG. 21 is applied, the rotation period (one rotation time) of the motor shaft is a natural number of a half rotation period of the drive roller.

[Embodiment 7]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment.
In the configuration using the friction transmission and the traction transmission as in the sixth embodiment, when the image output operation is performed with a steady slip (a constant slip amount) in the image output operation although it changes depending on the temperature and the diameter, the above-mentioned With such a configuration, a sufficient effect can be obtained. However, if a non-steady and variable slip occurs due to a load change during the image output operation, the configuration of the sixth embodiment cannot correct it and causes uneven rotation of the photosensitive drum. . Therefore, in the present embodiment, the MR sensor 41 of FIG. 4 and the rotary encoder 48 of FIG. 5 that have detected the rotation of the motor shaft in the configuration of the first embodiment are installed on the output shaft as a configuration corresponding to the variable slip. is doing. A gear is installed on the output shaft of the planetary roller and the output shaft of the flat belt transmission mechanism, and the speed is increased by the gear and the encoder is installed.

  FIG. 26 shows a configuration example of the gear speed increasing mechanism and the encoder 48 in the drive control apparatus of the present embodiment. The pitch circles of the plurality of gears 310 to 313 constituting this gear speed increasing mechanism are designed to rotate at a period of a natural number of the rotation time of the photosensitive drum from the exposure position to the transfer position. Yes. The attachment position of the encoder 48 including the encoder panel 48a and the detector 48b is installed on the output shaft 314 of the gear speed increasing mechanism. With this configuration, it is possible to eliminate the influence of fluctuations in rotational speed due to not only steady slip but also variable slip, and increase the apparent encoder resolution. On the photosensitive drum side, the rod-shaped member or plate-shaped member (rotary disk) is installed in a form integrated with the photosensitive drum shaft or the photosensitive drum in the same manner as in the above-described embodiment. Detects angular rotation time variation. With such a configuration, it is possible to control to cope with a variable slip and reduce the fluctuation of one rotation period of the photosensitive drum. Further, since the plurality of gears 310 to 313 rotate at a period of a natural number of the time that the photosensitive drum rotates from the exposure position to the transfer position, the gear 1 generated by the plurality of gears. The influence on the expansion and contraction of the image due to the rotation fluctuation of the rotation cycle is small.

[Embodiment 8]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus according to the present embodiment are the same as those in the first embodiment. In the image forming apparatus according to the present embodiment, a toner image on each photosensitive drum is transferred to a sheet via an intermediate transfer belt, and a belt drive in which a rotation target to be controlled drives an intermediate transfer belt instead of the photosensitive drum 1. It differs from the image forming apparatus of the first embodiment in that it is a roller. The contents of the rotational drive control described in the first embodiment and the third to seventh embodiments can be applied horizontally to the rotational drive control of the belt drive roller of the present embodiment.

FIG. 27 is a schematic configuration diagram of the image forming apparatus of the present embodiment. In the present embodiment, the intermediate transfer belt 201 which is an endless belt body passes through the primary transfer position Pt1 of the four photosensitive drums 202 to 205 and the secondary transfer position Pt2 on the paper transport path 206. And a plurality of support rollers 207 to 210. Then, a change in one rotation cycle of the driving roller 207 that is one of the plurality of support rollers is detected, and motor rotation control is performed on the motor that drives the driving roller 207 based on the detection result.
Further, in the image forming apparatus of the present embodiment, the intermediate transfer belt 201 passes between the primary transfer positions Pt1 of the photosensitive drum through the rotation cycle of at least one rotary member constituting the drive transmission unit including the drive roller 207. It is set to a natural number of a time, or to a natural number of a time that the intermediate transfer belt 201 passes through the secondary transfer position Pt2 for transferring from the primary transfer position of the photosensitive drum to the sheet. In the configuration of FIG. 4 described above, as described in the first embodiment, the motor shaft gear 46 is rotated at one cycle of a natural number of the cycle in which the predetermined angle rotation time variation detector 50 rotates the predetermined angle. It is configured. That is, when the time variation detector 50 within the predetermined angle is for detecting the predetermined angle of 180 degrees as shown in FIG. 1, FIG. 10, or FIG. 21, the motor shaft gear 46 has the half rotation period of the gear 47. It is comprised so that it may rotate with the period of 1 / natural number. As a result, it is possible to measure the time variation within a certain angle that is not affected by the rotation period variation of the gear 46. In addition, the rotation period of the motor shaft gear 46 is configured such that the intermediate transfer belt 201 rotates at a period that is a natural number of the time that the intermediate transfer belt 201 passes the inter-photosensitive-drum transfer portion distance Lst. As a result, the amount of color misregistration between the colors due to the fluctuation of the period due to the eccentricity of the motor shaft gear 46 and the accumulated tooth pitch error can be reduced. Alternatively, the rotation cycle of the motor shaft gear 46 is rotated at a cycle that is a fraction of a natural number of the time that the intermediate transfer belt passes the distance Ltr that moves from the primary transfer position to the secondary transfer position of the photosensitive drum. Constitute. As a result, the speed fluctuation phases at the primary transfer position and the secondary transfer position coincide with each other, so that the speed difference (primary transfer condition) in the primary transfer of the photosensitive drum with respect to the intermediate transfer belt 201 and the transfer paper are reduced. On the other hand, the speed difference (secondary transfer conditions) in the secondary transfer of the intermediate transfer belt has an inverse relationship. Thereby, the expansion and contraction of the pixels can be reduced.

  In many tandem type image forming apparatuses, a plurality of photosensitive drums are arranged at an equal pitch. That is, the same effect can be obtained for each color as long as both rotation cycle conditions between the primary transfer position of the photosensitive drum 202 and the photosensitive drum 203 and between the primary and secondary transfer positions are satisfied.

  Correction of the periodic fluctuation of the motor shaft can be similarly realized by using the object to be detected using the disk or mark of the plate-like member of FIG. 7 described in the fourth embodiment. In the rotation control of the driving roller 207, the transmission means shown in the fifth to seventh embodiments may be used. In addition, in the image forming apparatus, the rotation control described in the first embodiment and the third to seventh embodiments is similarly used for the transfer roller and the transfer roller (hereinafter referred to as “registration roller”) that sends the transfer paper to the image forming unit. can do. If the transfer roller has a rotation fluctuation of one rotation cycle, expansion / contraction and displacement of the pixel occur due to a speed difference between the primary transfer position and the secondary transfer position. Also in the registration roller, the rotation fluctuation in one rotation cycle becomes the transfer paper conveyance speed fluctuation as it is, and pixel expansion / contraction, positional deviation, and color deviation occur. By suppressing rotational fluctuations of the transfer roller and the registration roller, it becomes possible to transfer an image with higher accuracy.

[Embodiment 9]
Next, an image forming apparatus according to still another embodiment will be described. The basic configuration and operation of the image forming apparatus of the present embodiment are the same as those of the first and eighth embodiments. In the image forming apparatus according to the present embodiment, the controlled object rotating body is not a cylindrical rotating body such as a photosensitive drum or a driving roller but an endless belt body such as an intermediate transfer belt. 8 different from the image forming apparatus. The configuration for transferring the toner image on each photoconductor drum to a sheet via an intermediate transfer belt is the same as in the eighth embodiment.
In the first to eighth embodiments, the drive control method for reducing the rotation fluctuation of one rotation cycle of the cylindrical rotating body such as the photosensitive drum and the driving roller has been described. This drive control method can also be applied to the case where the target rotating body is an endless belt body such as an intermediate transfer belt.

  First, rotation fluctuations (conveyance speed fluctuations) that occur when an endless belt body (hereinafter referred to as “endless belt”) 211 such as an intermediate transfer belt used in the image forming apparatus makes one rotation (one turn) will be described. In the intermediate transfer belt of the image forming apparatus, a seamless endless belt (seamless belt) is mainly used. As a manufacturing method of this endless belt, for example, a centrifugal molding method in which a raw material solution is cast in a rotating mold and fired is used. The belt manufactured by such a molding method has a thickness deviation over the entire circumference of the belt due to the roundness of the mold, the bias of the injected raw material solution, and the like.

  FIG. 28 is a graph showing the thickness distribution of the endless belt produced by the above manufacturing method. As shown in FIG. 28, the thickness of the endless belt is not uniform, and has a thickness distribution over one circumference of the belt. When the driving roller is rotated at a constant speed and conveyed using such an endless belt, the conveying speed of the belt flat surface portion (stretching portion) increases when a thick portion of the endless belt is wound around the driving roller. Conversely, when a thin portion of the endless belt is wound around the driving roller, the conveyance speed of the belt flat surface portion (stretching portion) decreases. As described above, it is known that the transport speed of the endless belt also fluctuates in one rotation cycle of the belt according to the thickness distribution of the endless belt.

  FIG. 29 shows a schematic configuration of a drive control system that detects and controls the rotation fluctuation in one rotation cycle of the endless belt of the present embodiment. The endless belt 211 is stretched around a drive roller 212, a first driven roller 213, and a second driven roller 214 as a support rotating body. The endless belt 211 is conveyed in the direction of the arrow by rotating the driving roller 212 to which the rotational driving force is transmitted via the driving shaft 212a. The drive shaft 212a of the drive roller 212 is driven by a drive motor (not shown) and drive transmission means (not shown). The configuration of the drive system that transmits the rotational driving force from the drive motor shaft to the drive shaft 212a via the drive transmission means can be the same as that shown in FIG. 4, for example. In this embodiment, instead of the photosensitive drum shaft rotation detecting means, a predetermined angle rotation time variation detector for detecting a time for which the endless belt 211 rotates a predetermined angle, and a detection device for detecting the passage thereof. A belt rotation detecting means as a second detecting means is provided. As shown in FIG. 29, the belt rotation detecting means is constituted by mark members 215 and 216 as predetermined angle rotation time fluctuation detectors, and a detecting device 218 for detecting the passage of the mark member. As the mark members 215 and 216 installed on the endless belt 211, various members can be used in combination with the detection device 218. For example, in the case of the detection device 218 using an optical element, a mark member that reflects light, a mark member that blocks light, or a mark member that transmits light can be used. In the case of the detection device 218 using a magnetic sensor, a mark member made of a magnetic material can be used. Such mark members 215 and 216 are installed at positions where the phase of the rotation angle τ is separated when the circumference of the belt is 2π [radians], and the endless belt 211 is detected by detecting the mark members. It can be seen that τ [radian] has been rotated. The mark members 215 and 216 may be configured to fill the space between the rotation angles τ in FIG. However, the detection sensitivity is highest when τ = π [radian]. Under this condition, the detection mark member may be inserted in the middle of one half cycle so that it can be understood which half cycle is measured.

  In the drive control system of FIG. 29, assuming that one rotation period of the drive transmission mechanism including the driving roller 212 that is greatly affected by the period fluctuation is a natural number of the time during which the endless belt 211 is conveyed by the rotation angle τ, Belt period fluctuation detection that is not easily affected can be performed. Accordingly, one rotation cycle of the drive transmission mechanism including the drive roller, which is greatly affected by the cycle fluctuation, is determined between the photosensitive drum 202 and the photosensitive drum 203 or the primary transfer position and the secondary transfer position in FIG. Is set to a natural fraction of the time that the endless belt 211 passes through. Furthermore, one rotation cycle of the drive transmission mechanism is set to a natural number of a time during which the belt 211 passes by the rotation angle τ. With these settings, a high-quality image without color shift and pixel expansion / contraction can be obtained.

  In addition, when the endless belt 211 has a component (second harmonic component) in which the thickness variation changes in addition to one cycle for one rotation and further two cycles in one rotation, as shown in FIG. A mark member 217 is provided at a position separated by the rotation angle τ / 2. First, one rotation period component of the endless belt 211 is corrected, and then the second harmonic component is corrected. If the thickness variation of the third harmonic component or the nth harmonic component (where n is a natural number) is corrected, the mark member is formed at a position separated from the mark member 216 by the rotation angles τ / 3, τ / n. Then, the correction may be performed sequentially. However, one rotation period of the transmission mechanism including the drive roller, which is greatly affected by the period fluctuation, is set to a natural fraction of the time during which the belt is conveyed by the rotation angle τ / n.

  Using the detection result of the predetermined rotation angle rotation time of the endless belt 211 detected by the belt rotation detecting unit of the present embodiment, the rotation of one cycle of the endless belt is performed as in the case of the photosensitive drum rotation control described in the first embodiment. The amplitude and phase of the fluctuation component are calculated. Then, taking into account the reduction ratio of the drive transmission means, the radius of the drive roller, and the average thickness of the belt, it is converted into the rotational speed fluctuation amplitude of the motor shaft, and the sine wave reference signal so as to cancel the rotational fluctuation of one cycle of the endless belt. And drive control.

  FIG. 30 is a schematic configuration diagram showing another configuration example of the belt drive control system similar to FIG. In FIG. 30, the drive shaft 222a of the drive roller 222 is driven by a drive motor (not shown) and drive transmission means (not shown). The configuration of the drive system that transmits the rotational driving force from the drive motor shaft to the drive shaft 212 via the drive transmission means can be the same as that shown in FIG. 4, for example. Further, in place of the photosensitive drum shaft rotation detecting means, a predetermined angle rotation time fluctuation detecting body (hereinafter referred to as “detected body”) for detecting a time during which the endless belt 211 rotates a predetermined angle is provided. Furthermore, a belt rotation detecting means as a second detecting means comprising a detecting device for detecting the passage of the detected object is provided. A rotary encoder (not shown) is attached to the rotation shaft of the first driven roller 223. In the present embodiment, the detected body 225 is provided on the rotation shaft or the end surface of the second driven roller 224. As the detected body 225, a plate-like member having fan-shaped blade portions 225 a and 225 a ′ 225 b as shown in FIG. 21 is provided on the rotation shaft of the second driven roller 224. Alternatively, three marks having the same shape may be formed on the end face of the second driven roller 224. By detecting the passage of the detection object 225 by the detection device 226, the periodic fluctuation of the first driven roller 223 can be corrected. That is, the rotation time for the second driven roller 224 to rotate the central angle β is one rotation cycle of the first driven roller 223. One rotation cycle of the shaft of the first driven roller 223 is set to a half rotation cycle of the rotation shaft of the second driven roller 224 and a natural number of one cycle of the belt.

Here, even if an attempt is made to feed back the rotary encoder output to rotate the first driven roller 223 at a constant speed, the second driven roller 224 rotates the second driven roller one rotation period due to the eccentricity of the second driven roller 224. Cause fluctuations. The rotation fluctuation of the first driven roller is caused by the eccentricity of the rotary encoder and the eccentricity of the first driven roller 223 and the like. Therefore, the periodic fluctuation of the second driven roller 224 is first corrected by the method shown in the fourth embodiment, and then the cyclic fluctuation of the first driven roller 223 is corrected. Thereafter, the belt thickness variation is corrected. The detection device 226 detects one rotation of the shaft of the second driven roller 224 by detecting the detected object 225. The rotation period of the shaft of the second driven roller 224 is set to a natural number of one period of the belt. It is known that the effective belt thickness that determines the rotation of the driven roller when the endless belt 211 is wound around the second driven roller 224 is about half of the belt thickness. Therefore, when the average belt thickness is B, the relationship between the belt circumferential length Lb and the radius Re of the second driven roller 224 is expressed by equation (17).

Here, it is assumed that the first driven roller 223 and the second driven roller 224 have been subjected to period fluctuation correction. Further, the belt thickness variation Δb is approximately expressed by the equation (18). In equation (18), ωb is the belt 1 rotation angular frequency, b is the belt thickness fluctuation amplitude, and α is the phase of the belt thickness fluctuation Δb at the driving roller 222 at time zero.

Then, the rotational speed ω of the second driven roller 224 when the first driven roller 223 is controlled to a constant rotation ωo is approximately expressed by the following equation (19).

Where ωb is the belt 1 rotation angular frequency, R1 is the first driven roller radius, R2 is the second driven roller radius, and τo is the time for the belt to pass between the first driven roller 223 and the second driven roller 224. Is a value at which τo / ωb. That is, the rotational speed ω of the second driven roller 224 is not simply caused by the belt 211 coming into contact with the second driven roller and being subjected to belt thickness fluctuations, but also when the first driving roller is in contact with the belt 211. ing. In order to simplify the discussion now, assuming that R1 >> B and R2 >> R1, equation (19) is approximately as follows.

  In this case, the second driven roller 224 may be changed according to the belt thickness fluctuation. For example, when the driven shaft of the second driven roller 224 rotates 10 times in one belt cycle, the time required for the belt half cycle is detected by detecting the time when the driven shaft rotates 5 times. The home position of one rotation of the belt 211 can be detected by detecting a mark member provided on the belt 211 so as to indicate the home position. The home position for one rotation of the belt 211 comes to the home position for the rotation of the driven shaft of the second driven roller 224 after the power is turned on to the device on which the belt drive system is mounted and the correction is started. It is also possible to detect by continuing to count the timing. Using such detection means, the amplitude and phase of the rotational fluctuation component of one belt cycle can be calculated in the same manner as in the photosensitive drum rotation control shown in the first embodiment. However, in practice, as described above, rotational fluctuations are added which are influenced by fluctuations in the thickness of the belt at the places where the first driven roller 223 and the second driven roller 224 are wound. Therefore, in order to control with high accuracy such that the relationship of R2 >> R1 cannot be ignored, the belt cycle variation may be obtained and corrected based on the equation (19).

  FIG. 31 is a schematic configuration diagram showing another configuration example of the belt drive control system similar to FIG. In FIG. 31, the drive shaft 222a of the drive roller 222 is driven by a drive motor and drive transmission means (not shown). The configuration of the drive system that transmits the rotational driving force from the drive motor shaft to the drive shaft 212 via the drive transmission means can be the same as that shown in FIG. 4, for example. In the present embodiment, instead of the photosensitive drum shaft rotation detecting means, a predetermined angle rotation time variation detector for detecting a time during which the endless belt 211 rotates a predetermined angle and a detection device for detecting the passage thereof are provided. Belt rotation detection means is provided as second detection means. Further, in place of the photosensitive drum shaft rotation detecting means, a detected body for detecting a time during which the endless belt 211 rotates a predetermined angle is provided. Furthermore, a belt rotation detecting means as a second detecting means comprising a detecting device for detecting the passage of the detected object is provided. In the present embodiment, the detected body 225 is provided on the rotation shaft or the end surface of the second driven roller 224. As the detected body 225, a plate-like member having fan-shaped blade portions 225 a and 225 a ′ 225 b as shown in FIG. 21 is provided on the rotation shaft of the second driven roller 224. Alternatively, three marks having the same shape may be formed on the end face of the second driven roller 224. By detecting the detected object 225 by the detection device 226, the rotation period variation of the driving roller 222 can be corrected. That is, the time for rotating the central angle β of one blade portion 225 a ′ among the plurality of blade portions constituting the detected body 225 is the predetermined angle rotation time of the driving roller 222. The rotation period of the shaft 222a of the driving roller 222 is set to a half rotation period of the shaft of the driven roller 224 and a natural number of one period of the belt. Even if the driving roller 222 is rotated at a constant speed, the driven roller 224 causes a periodic fluctuation of one rotation period of the driving roller due to the eccentricity of the driving roller 222, and is superposed on the periodic fluctuation of the rotation of the driven roller due to the eccentricity of the driven roller 224. Will occur. First, the periodic fluctuation of the driven roller 226 is corrected by the method shown in the fourth embodiment, and then the cyclic fluctuation of the driving roller 222 is corrected.

Next, the rotational fluctuation due to the belt thickness fluctuation is corrected. The detection device 226 detects one rotation of the shaft of the driven roller 224 by detecting the passage of the blade portion of the detected object 225. The rotation period of the shaft of the driven roller 224 is set to 1 / natural number of one belt period. It is known that the effective belt thickness that determines the rotation of the shaft of the driven roller 224 when the belt 211 is wound around the driven roller 224 is about half the thickness of the belt 211. Therefore, when the average belt thickness is B, the relationship between the circumferential length Lb of the belt 211 and the radius Re of the driven roller 224 is expressed by the following equation (21).

Here, it is assumed that the period fluctuations of the driving roller 222 and the driven roller 224 are corrected. In addition, the thickness variation Δb of the belt 211 is approximately expressed by the equation (18).

Then, the rotational speed ω of the driven roller 226 when the driving roller 222 is controlled to a constant rotation ωo is approximately expressed by the following equation (22).

However, ωb is a belt 1 rotation angular frequency, R1 is a driving roller radius, R2 is a driven roller radius, and τ is a value at which τ / ωb is a time during which the belt passes between the driving roller 222 and the driven roller 224. In other words, the rotational speed ω of the driven roller 224 occurs not only when the belt 211 comes into contact with the single driven roller 224 but is subjected to belt thickness fluctuations, but also when the driving roller 222 comes into contact with the belt. In order to simplify the discussion now, if R1 >> B, R2 >> R1, the expression (22) is approximately as follows.

  In this case, the driven roller 224 may be changed according to the belt thickness fluctuation. For example, when the driven shaft of the driven roller 224 rotates 10 times in one belt cycle, the time required for the belt half cycle is detected by measuring the time when the driven roller shaft rotates 5 times. The home position of one rotation of the belt 211 can be detected by detecting a mark member provided on the belt 211 so as to indicate the home position. The home position for one rotation of the belt 211 comes to the home position for the rotation of the driven shaft of the second driven roller 224 after the power is turned on to the device on which the belt drive system is mounted and the correction is started. It is also possible to detect by continuing to count the timing. Using such detection means, the amplitude and phase of the rotational fluctuation component of one belt period can be calculated in the same manner as in the photosensitive drum rotation control shown in the first embodiment. However, in practice, as described above, rotational fluctuations are applied which are affected by the thickness fluctuation of the belt 211 at the portions where the driving roller 222 and the driven roller 224 are wound. Therefore, in order to control, the belt cycle variation may be obtained and corrected based on the above equation (22).

As described above, among the belt drive control systems of FIGS. 29, 30 and 31 exemplified in the ninth embodiment, the belt drive control system of FIG. 30 is particularly effective when a slip occurs between the drive roller 222 and the belt 211. is there.
Further, in the belt drive control system exemplified in this embodiment, it is not necessary to accurately measure the amplitude and movement of the rotation fluctuation of one rotation period of the belt 211 due to the belt thickness fluctuation, and a plurality of movement times of the half period of the belt 211 are set. It may be measured once.

In each of the above embodiments, the second detection unit and at least one component such as a photosensitive drum, a charging unit, a developing unit, and a cleaning unit may be integrally coupled as a process cartridge. . In this case, the second detection means included in the process cartridge can be integrated and detached and exchanged, and the convenience of maintenance is enhanced.
This process cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer. In the image forming apparatus having the process cartridge having the second detection means, the photosensitive drum is rotationally driven at a predetermined peripheral speed. In the rotation process of the photosensitive drum, the charging device means receives a uniform charge of positive or negative predetermined potential on its peripheral surface, and then receives image exposure light from image exposure means such as slit exposure and laser beam scanning exposure. . In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photosensitive drum, and the formed electrostatic latent images are then developed with toner by a developing unit. The developed toner image is sequentially transferred by the transfer unit to the transfer material fed between the photosensitive drum and the transfer unit from the paper feeding unit in synchronization with the rotation of the photosensitive drum. The transfer material that has received the image transfer is separated from the peripheral surface of the photosensitive drum, introduced into the image fixing means, the image is fixed, and printed out as a copy (copy). The surface of the photosensitive drum after the image transfer is cleaned by removing the transfer residual toner by the cleaning means, and after being further discharged, it is repeatedly used for image formation.

As described above, according to each embodiment, a motor as a rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotating body rotates a predetermined rotation angle at the time of control by each of these control patterns. Measure the rotation time. Based on the measurement result of each rotation time measured in this way, the amplitude and phase of the rotational speed fluctuation in one rotation period of the controlled object rotating body are obtained. Then, by controlling the drive motor as the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, the rotational speed fluctuation of one rotation cycle of the controlled rotating body due to the eccentricity of the drive transmission rotating body is suppressed. can do. In addition, since the rotation time can be measured for one predetermined rotation angle during one rotation of the rotating object to be controlled, it is not necessary to use a high-precision rotary encoder that causes a high cost.
The driving conditions in the control patterns are set such that, for example, rotational speed fluctuations in one rotation period having different amplitudes or phases occur in the control target rotating body such as the photosensitive drum, the driving roller, and the intermediate transfer belt.

In each embodiment, a rotational driving force is applied from a rotational driving source to a rotating body to be controlled such as a photosensitive drum, a driving roller, and an intermediate transfer belt via a driving transmission rotating body such as a plurality of gears constituting a driving transmission unit. When transmitting, it is preferable to control as follows. That is, at the time of control by each control pattern, about the rotation time when at least one drive transmission rotator at a position other than the rotation axis of the control target rotator among the plurality of drive transmission rotators rotates a predetermined rotation angle Also measure. Based on the measurement results of these rotation times, the amplitude and phase of the rotational speed fluctuation in one rotation cycle of the drive transmission rotating body to be measured can be obtained. Based on the amplitude and phase of the rotational speed fluctuation, the rotational speed of the rotational speed of the drive transmission rotator and the rotational speed of the rotational speed of the driving transmission rotator are controlled along with the rotational speed fluctuation of the rotational speed of the rotational body to be controlled. Variations can be suppressed.
Further, when measuring the rotation time of the predetermined rotation angle not only for the controlled object rotating body but also for the drive transmission rotating body in this way, the rotation time measurement and the rotation driving based on the amplitude and phase are performed in the following order. Source control is preferably performed. That is, the measurement of the rotation time and the control of the rotation drive source based on the amplitude and phase are sequentially performed in order from the longer one rotation cycle of the plurality of rotating bodies to be measured. By performing the control in this order, the rotation time can be measured and the rotation drive source can be controlled based on the amplitude and phase in an order that is not easily influenced by the rotation fluctuations of other rotating bodies. Accurate drive control can be performed.
In each embodiment, the ratio between the rotation cycle of the motor shaft, which is the rotation shaft of the rotary drive source, the rotation cycle of the drive transmission rotor, and the rotation cycle of the controlled object rotor is a natural number ratio. It is preferable to configure. Thus, by making the ratio of each rotation cycle a natural number ratio, the phase relationship among the rotation cycles of the motor shaft, the controlled object rotating body, and the drive transmission rotating body becomes a constant relationship. Accordingly, during the control of the above-described plurality of types of control patterns, the rotation time of the default rotation angle of the controlled object rotating body is set to be the same as the rotational fluctuation of the motor shaft and the drive transmission rotating body whose cycle is shorter than the rotational fluctuation of the controlled object rotating body. Can be measured in phase. Further, the rotation time of the predetermined rotation angle of the drive transmission rotating body can be measured with the same phase of the rotation fluctuation of the motor shaft whose cycle is shorter than the rotation fluctuation of the drive transmission rotation body. Therefore, the measurement accuracy of the rotation time of the predetermined rotation angle of the controlled object rotator or the drive transmission rotator is increased, and the rotation drive source can be controlled so that the rotational fluctuation of the controlled object rotator or the drive transmission rotator can be reliably suppressed.
Here, the rotation cycle of at least one of the plurality of drive transmission rotators constituting the drive transmission means (hereinafter referred to as “specific drive transmission rotator”) is Tr, the rotation cycle of the controlled rotor is To, and the default rotation It is preferable that n × Tr = To × (θo / 2π) holds when the angle is θo and the natural number is n. In this case, even if a speed fluctuation with a cycle shorter than one rotation period is superimposed on the rotation of the rotating body to be controlled due to the eccentricity of the specific drive transmission rotating body or the accumulated tooth pitch error, the rotational speed fluctuation with the short cycle is superposed. The rotation time of the predetermined rotation angle is measured with substantially the same phase. Therefore, the rotation fluctuation due to the eccentricity of the specific drive transmission rotating body is less likely to affect the measurement result of the rotation time of the predetermined rotation angle detected by the second detection means, and more accurate rotation drive control is possible. Become.
In each embodiment, the rotation time of the predetermined rotation angle may be measured even after the control of the rotational drive source based on the amplitude and phase of the rotational speed fluctuation is started. Based on the measurement result of the rotation time, the amplitude or phase of the rotational speed fluctuation in one rotation period of the rotating object to be controlled is newly obtained, and the rotational speed fluctuation amplitude used for controlling the rotational drive source based on the amplitude or phase and Correct the phase. Thus, by starting the control of the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, after updating the rotational speed fluctuation amplitude or phase of the controlled rotational body, the rotational fluctuation of the controlled rotational body due to the environment and time It will be possible to respond to changes in
In each embodiment, the predetermined rotation angle is preferably π [rad]. The angular velocity variation of the controlled object rotating body in question in this embodiment is a fluctuation of one rotation cycle, and the angular speed of the controlled object rotating body is higher than the average angular velocity every time the controlled object rotating body rotates by π [rad]. The rotation region and the low-speed rotation region smaller than the average angular velocity are repeated. Accordingly, when the default rotation angle is set to π [rad], the rotation time of the default rotation angle can be measured in a period substantially corresponding to either the high speed rotation region or the low speed rotation region. It becomes possible to increase the sensitivity to time to the maximum sensitivity. Therefore, it is possible to detect the amplitude and phase of the rotational fluctuation with the highest sensitivity within the range of the predetermined rotation angle of 0 to 2π [rad], and to perform more accurate drive control.

In each embodiment, the second detection means (photoreceptor drum shaft rotation detection means) has a central portion in the longitudinal direction attached to a rotation shaft of a rotating body to be controlled such as a photoconductive drum, and a longitudinal end portion thereof is covered. It can be configured using a rod-shaped member (detected body) having a detection unit. In this case, as compared with the case where a commercially available rotary encoder is used, the detection means has a very simple configuration, and the cost can be reduced.
Further, in each embodiment, the second detection unit is configured such that the central portion is attached to the rotation shaft of the rotating body to be controlled such as the photosensitive drum and the detected portion is partly in the rotational direction at a position away from the central portion. It can comprise using the plate-shaped member which has. For example, it can comprise using the plate-shaped member which consists of a fan-shaped blade | wing part which has an edge part as a to-be-detected part. Also in this case, compared with the case where a commercially available rotary encoder is used, the detection means has a very simple configuration, and the cost can be reduced.
Further, in each embodiment, the second detection means is configured using a mark member as a detected portion provided in a part of the rotation direction on the outer peripheral surface of the rotating body to be controlled such as a photosensitive drum. Can do. Also in this case, compared with the case where a commercially available rotary encoder is used, the detection means has a very simple configuration, and the cost can be reduced. In particular, in this case, since the number of parts provided independently of the controlled rotating body such as the photosensitive drum is reduced, the cost can be reduced and the space can be saved.
In each embodiment, the second detection unit can be configured using a detected portion formed by cutting out a part of the rotation direction of the rotation shaft of a rotating body to be controlled such as a photosensitive drum. Also in this case, since the number of parts provided independently of the rotating body to be controlled such as the photosensitive drum is reduced, the cost can be reduced and the space can be saved.
In addition, you may provide the detection apparatus which detects the to-be-detected part in the rod-shaped member, plate-shaped member, etc. as said to-be-detected body in the several places distant by the equal angle in the rotation direction of a to-be-detected part. In this case, the measurement result of the rotation time obtained by performing the averaging process on a plurality of sets of data detected by each detection device can be used. Therefore, detection errors due to eccentric mounting of rod-like members, plate-like members, and the like as detection bodies can be reduced, and highly accurate detection and drive control can be performed. In particular, it is preferable to provide the detection devices at two locations separated by π radians around the rotation axis of the rotating body to be controlled.
Further, a plurality of detected portions in the rod-shaped member, plate-shaped member, or the like as the detected body may be provided so as to be separated by an equal angle in the rotation direction. In this case, by simultaneously detecting a plurality of detected parts, detection errors due to mounting eccentricity of a rod-like member or plate-like member as a detected object are reduced, and highly accurate detection and drive control are possible. . In particular, it is preferable to provide the detected parts at two locations separated from each other by π radians around the rotation axis of the controlled object rotating body.
In addition, when a plurality of the detected parts are provided, one of the detected parts may be provided so as to be distinguishable from other detected parts. In this case, it is possible to determine the reference position for one rotation of the detected body such as a rod-shaped member or a plate-shaped member having the detected portion.

Moreover, in each embodiment, the detection apparatus which detects the to-be-detected part in the rod-shaped member, plate-shaped member, etc. as said to-be-detected body can be comprised using an optical sensor. In this case, since the passage timing of the detected part (edge part) of the detected object can be detected with high accuracy, highly accurate rotational drive control is possible.
Moreover, in each embodiment, the detection apparatus which detects the to-be-detected part in the rod-shaped member, plate-shaped member, etc. as said to-be-detected body can be comprised using a magnetic sensor. In this case, for example, when used in an image forming apparatus, detection can be performed without being affected by the contamination of the sensor due to toner adhesion, so the reliability of the rotational drive control device against the contamination is increased.

Further, as shown in the above embodiment, the drive control according to the present invention can be applied to the drive control of the photosensitive drum of the image forming apparatus. In this case, it is possible to suppress the rotation fluctuation of one rotation cycle of the photosensitive drum and the rotation fluctuation of one rotation cycle of the drive transmission rotating body such as a gear that transmits the rotation driving force to the photosensitive drum. Therefore, it is possible to reduce the positional deviation of the transferred image and the expansion / contraction of the pixels, thereby realizing high image quality.
Further, as shown in the above embodiment, the drive control according to the present invention can be applied to the drive control of the drive roller that drives the intermediate transfer belt of the image forming apparatus. In this case, it is possible to suppress the rotational fluctuation of one rotation period of the driving roller and the rotational fluctuation of one rotation period of the drive transmission rotating body that transmits the rotational driving force to the driving roller. Therefore, it is possible to reduce the positional deviation of the transferred image and the expansion / contraction of the pixels, thereby realizing high image quality.
Further, as shown in the above embodiment, the drive control according to the present invention can be applied to the drive control of the transport roller that transports the transfer paper of the image forming apparatus. In this case, it is possible to suppress the rotation fluctuation of one rotation cycle of the conveyance roller and the rotation fluctuation of one rotation cycle of the drive transmission rotating body that transmits the rotation driving force to the conveyance roller. Accordingly, it is possible to reduce the positional deviation of the transferred image and the pixel thickness and to realize high image quality.
Further, as shown in the above embodiment, the drive control according to the present invention can be applied to drive control of a transfer roller as a transfer member of an image forming apparatus. In this case, it is possible to suppress the rotation fluctuation of one rotation cycle of the transfer roller and the rotation fluctuation of one rotation cycle of the drive transmission rotating body that transmits the rotation driving force to the transfer roller. Therefore, it is possible to reduce the positional deviation of the transferred image and the expansion / contraction of the pixels that occur in the primary transfer and the secondary transfer, and to realize high image quality.

Further, as shown in the above embodiment, the drive control according to the present invention can be applied to the drive control of the intermediate transfer belt of the image forming apparatus. In this case, the rotational fluctuation (conveyance speed fluctuation) caused by the thickness fluctuation over the circumference of the intermediate transfer belt and the rotational fluctuation of one rotation cycle of the drive transmission rotating body that transmits the rotational driving force to the intermediate transfer belt are suppressed. be able to. Therefore, it is possible to reduce the positional deviation of the transferred image and the expansion / contraction of the pixels, thereby realizing high image quality.
In the case of driving and controlling an endless belt body such as an intermediate transfer belt, the rotation variation (conveying speed) of the belt body is detected with a simple configuration in which mark members are provided and detected at at least two locations on the belt body. Variation) and the like can be suppressed.
Also, the rotation period of the rotation shaft of the driven roller to which the belt body is stretched is set to a natural fraction of the rotation period of the belt body, and the belt body is rotated by a predetermined time by measuring one rotation time of the driven roller. You may measure the time which rotates a corner. In this case, with a simple configuration of detecting one rotation of the driven roller, it is possible to obtain an effect that it is possible to suppress the rotation fluctuation (conveyance speed fluctuation) of the belt body and the cost is further reduced. it can. In addition, highly accurate detection is possible without being affected by the rotational fluctuation component due to the eccentricity of the rotation shaft of the driven roller.
In addition, a rotary encoder may be attached to one of the rotation shafts of the two driven rollers over which the belt body is stretched, and the second detection means may be provided on the other rotation shaft. In this case, the second detection means can eliminate the rotation detection error due to the eccentricity of the rotary encoder, and the feedback control of the rotation shaft of the driven roller can be performed with higher accuracy.
Further, the second detection means is provided on the rotation shaft of the driven roller to which the belt body is stretched, and the belt body, the driven roller shaft, and the drive roller shaft are respectively rotated by a predetermined rotation according to the detection result of the second detection means. The time for rotating the corner may be measured. Based on the measurement result, the phase and amplitude of the rotational fluctuation of the belt body, the driven roller shaft, and the driving roller shaft can be obtained, and the belt body can be conveyed and driven with high accuracy.

Further, when the drive control according to the present invention is applied to the drive control of the photosensitive drum of the image forming apparatus, the rotation cycle of the drive transmission rotating body such as a gear rotates the angle at which the photosensitive drum forms the exposure and transfer unit. It is preferable to make it a natural fraction of the period. In this case, even if rotational fluctuation occurs due to the eccentricity of the drive transmission rotator or the accumulated tooth pitch error, the displacement of the transferred image can be reduced.
In particular, as in each embodiment, a tandem type image is provided with a plurality of photosensitive drums arranged along the moving direction of the intermediate transfer belt, and a drive transmission rotating body that transmits the rotational driving force of the drive source to the intermediate transfer belt. In the case of a forming apparatus, the following configuration is preferred. That is, it is preferable that the rotation cycle of the drive transmission rotator is equal to the time required for the surface of the intermediate transfer belt to pass the pitch between the photosensitive drums. In this case, an image is transferred in synchronism with the phase of the detected rotational fluctuation of each photoconductive drum with respect to the transfer material. Therefore, transfer conditions (intermediate transfer belt and photoconductive drum between The speed difference is the same, and the color shift is reduced.

  In the tandem type image forming apparatus, when the drive roller for driving the intermediate transfer belt is driven and controlled, the following configuration is preferable. That is, it is preferable that the rotation cycle of the drive transmission rotator including the drive roller is equal to the time during which the surface of the intermediate transfer belt passes the pitch between the photosensitive drums. In this case, even if rotational fluctuation occurs due to the eccentricity of the drive transmission rotating body or the accumulated tooth pitch error, it is possible to reduce the displacement of the transferred image. The rotation cycle of the drive transmission rotator is the same even when the surface of the intermediate transfer belt moves from the primary transfer position facing the photosensitive drum to the secondary transfer position facing the transfer material. An effect can be obtained.

In each embodiment, it is preferable to use a large-diameter gear for the final stage of the drive transmission mechanism. In this case, since the number of parts can be reduced by one-stage deceleration and the rotational speed of the motor can be increased, the motor efficiency can be increased. Further, it is possible to make it difficult to visually recognize the banding period due to the single pitch error of the large-diameter gear by reducing it on the image.
In each embodiment, a planetary gear mechanism may be used as the drive transmission mechanism. In this case, high speed reduction is possible in a small space, and the apparatus can be made compact.
In each embodiment, a planetary roller mechanism may be used as the drive transmission mechanism. In this case, there is no single pitch banding generated by the gears, and high image quality can be realized.
In each embodiment, a flat belt mechanism may be used as the drive transmission mechanism. Also in this case, there is no single pitch banding generated by the gears, and high image quality can be realized.
Further, according to each embodiment, it is possible to correct slip even in a transmission mechanism in which slip occurs in the drive transmission mechanism such as a planetary roller or a flat belt. In addition, the cost can be reduced by using an inexpensive encoder with low resolution when detecting slippage.

In each embodiment, the control, detection, and data processing for obtaining the amplitude and phase of the rotation fluctuation in one rotation cycle of the rotating object to be controlled such as the photosensitive drum can be performed in the manufacturing process of the image forming apparatus. . In this case, the drive control can be performed in response to the user's output request.
Further, in each embodiment, control, detection, and data processing for obtaining the amplitude and phase of the rotation fluctuation of one rotation cycle of the rotating object to be controlled such as the photosensitive drum are actually installed and used in the image forming apparatus. It may be performed in a place where In this case, it is possible to perform drive control corresponding to the environment and changes over time.

6 is a flowchart showing a procedure of data processing and control operation for correcting and controlling the rotation fluctuation of one rotation cycle of the photosensitive drum in the rotation drive control device according to the embodiment of the present invention. 1 is a schematic configuration diagram of a color printer as an image forming apparatus according to an embodiment. FIG. 3 is a block diagram illustrating a configuration of a control system of the color printer. The block diagram explaining the rotation drive mechanism of the motor in the control system. The block diagram explaining the control structure of DSP in the rotation drive mechanism. Explanatory drawing which shows the detailed structure of DSP, a driver, and a motor in the rotation drive mechanism. The block diagram explaining the rotational drive mechanism of the motor which concerns on a modification. The characteristic view which shows the time characteristic of a photoreceptor drum axis | shaft rotation nonuniformity. The frequency characteristic figure which shows the frequency component of the same photoreceptor drum axis | shaft rotation unevenness. (A) And (b) is explanatory drawing which shows one structural example of the photoreceptor drum shaft rotation detection means comprised using the rod-shaped member. (A) And (b) is explanatory drawing which shows one structural example of the photoconductor drum axis | shaft rotation detection means comprised using the plate-shaped member. (A)-(d) is explanatory drawing of the plate-shaped member which concerns on a modification. (A) And (b) is explanatory drawing which shows the photosensitive drum shaft rotation detection means which concerns on a modification. Explanatory drawing which shows the photosensitive drum shaft rotation detection means which concerns on another modification. Explanatory drawing of phase alignment between photoconductor drums in the image forming apparatus which concerns on other embodiment. Explanatory drawing which shows the mode of a detection of a rod-shaped member. The timing chart of the output pulse of a detection apparatus when the phase alignment correction | amendment operation | movement of each photoconductor drum is completed. FIG. 10 is an explanatory diagram showing a positional relationship between an optical writing position Pex and a transfer position Pt on a photosensitive drum in an image forming apparatus according to another embodiment. (A)-(d) is a plate-shaped member for detecting both the rotation fluctuation of one rotation period of a photosensitive drum and the rotation fluctuation of one rotation period of a motor shaft in an image forming apparatus according to another embodiment. Explanatory drawing which shows the example of a structure. (A)-(c) is explanatory drawing which shows the structural example of the photosensitive drum shaft rotation detection means comprised using the plate-shaped member which has the blade | wing part (or detection mark) which concerns on a modification. FIG. 3 is an explanatory diagram showing a configuration example of a photosensitive drum shaft rotation detection unit suitable for driving a controlled object rotating body other than the photosensitive drum at a one-step speed reduction from a motor. The perspective view which shows the structural example of the planetary gear reduction mechanism used for the image forming apparatus which concerns on other embodiment. Explanatory drawing which shows the mode of the planetary rotation of the planetary gear in the planetary gear reduction mechanism. (A) is front sectional drawing which shows the structural example of the planetary roller speed reducer using the traction transmission used with the image forming apparatus which concerns on other embodiment. (B) is side surface sectional drawing which shows the structure of the planetary roller speed reducer concretely. The top view which shows the structural example of the reduction gear using the flat belt used with the image forming apparatus which concerns on other embodiment. FIG. 10 is an explanatory diagram illustrating a configuration example of a gear speed increasing mechanism and an encoder in a drive control device of an image forming apparatus according to another embodiment. Furthermore, the schematic block diagram of the image forming apparatus of embodiment. The graph which shows thickness distribution of an endless belt. The schematic block diagram of the belt drive control system which detects and controls the rotation fluctuation | variation of 1 rotation period of an endless belt. The schematic block diagram which shows the other structural example of a belt drive control system. The schematic block diagram which shows the further another structural example of a belt drive control system.

Explanation of symbols

1 (1a to 1d) Photosensitive drum 1 'Rotating shaft 2a to 2d Laser scanner 3 Conveyor belt 4 Drive roller 5 Fixing device 6a to 6d Motor 10 Color printer 11 Printer control unit 40 Motor 46, 47 Gear 50 Predetermined angle rotation time fluctuation Detecting object (detected object)
51 Detection Device 501 Bar-shaped Member 502-507 Plate-shaped Member

Claims (44)

A rotational angular displacement or a rotational angular velocity of a rotational shaft of a rotational drive source that generates a rotational driving force transmitted to the controlled rotational body through a plurality of drive transmission rotational bodies is detected, and the rotational drive source is based on the detection result. A rotational drive control method for controlling the rotation of the controlled rotating body by controlling
Controlling the rotational drive source with two or more kinds of control patterns having different driving conditions;
At the time of control by each control pattern, at least one of the plurality of drive transmission rotators at a position other than the rotation axis of the control object rotator, together with the rotation time when the control object rotator rotates a predetermined rotation angle. Measure the rotation time when the drive transmission rotator rotates at the predetermined rotation angle,
Based on the measurement results of these rotation times, the amplitude and phase of the rotational speed fluctuation in one rotation period of the control object rotator and the drive transmission rotator to be measured are obtained ,
A rotating body drive control method, comprising: controlling the rotation drive source based on an amplitude and a phase of a rotational speed variation of the control object rotating body and the drive transmission rotating body to be measured . In the rotating body drive control method of Claim 1 ,
Rotating body drive characterized in that the rotational time is measured and the rotational drive source is controlled based on the amplitude and phase in order from the larger rotational period of the plurality of rotating bodies to be measured for the rotational time. Control method. In the rotating body drive control method according to claim 1 or 2 ,
The ratio between the rotation cycle of the rotation shaft of the rotary drive source, the rotation cycle of the drive transmission rotor, and the rotation cycle of the control target rotor is a natural number ratio, respectively. A rotating body drive control method. In the rotating body drive control method of Claim 3 ,
When at least one rotation period of the plurality of drive transmission rotators is Tr, the rotation period of the controlled object rotator is To, the predetermined rotation angle is θo, and a natural number is n, the following equation holds: Rotating body drive control method.
n × Tr = To × (θo / 2π) In the rotating body drive control method according to any one of claims 1 to 4 ,
After starting the control of the rotational drive source based on the amplitude and phase of the rotational speed variation, the rotational time is measured, and based on the measurement result, the rotational speed variation amplitude of one rotation period of the controlled rotating body Alternatively, a rotating body drive control method comprising: obtaining a phase and correcting the amplitude and phase of the rotational speed fluctuation used for controlling the rotational drive source based on the amplitude or phase. In the rotating body drive control method in any one of Claims 1 thru | or 5 ,
The rotating body drive control method, wherein the predetermined rotation angle is π [rad] . Rotation drive source, a plurality of drive transmission rotators for transmitting the rotation drive force of the rotation drive source to the controlled object rotator, and a first detection for detecting the rotation angular displacement or rotation angular velocity of the rotation shaft of the rotation drive source A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
Second detection for detecting that at least one drive transmission rotating body at a position other than the rotation axis of the control target rotating body rotates at a predetermined rotation angle among the plurality of drive transmission rotating bodies together with the control target rotating body. Means,
And control of the rotary drive source at more than one control pattern driving conditions are different from each other, rotate during control by the control pattern, the control target rotational member based on a detection result of the second detecting means default rotation angle And a rotation time when at least one drive transmission rotating body at a position other than the rotation axis of the control target rotating body rotates a predetermined rotation angle among the plurality of drive transmission rotating bodies. Then, based on the measurement results of these rotation times, the amplitude and phase of the rotational speed fluctuation in one rotation period of the control object rotator and the drive transmission rotator to be measured are obtained,
A rotator drive control apparatus comprising: a control body that controls the rotation drive source based on the amplitude and phase of rotation speed fluctuations of the control object rotator and the drive transmission rotator to be measured . In the rotating body drive control device according to claim 7 ,
The control means performs the measurement of the rotation time and the control of the rotation drive source based on the amplitude and phase in order from the larger rotation cycle of the plurality of rotating bodies that are the measurement objects of the rotation time. Rotating body drive control device. In the rotating body drive control device according to claim 7 or 8 ,
A rotator characterized in that a ratio between a rotation period of a rotation shaft of the rotation drive source, a rotation period of the drive transmission rotator, and a rotation period of the rotation object to be controlled is a natural number ratio. Drive control device. In the rotating body drive control device according to claim 9 ,
When at least one rotation period of the plurality of drive transmission rotators is Tr, the rotation period of the controlled object rotator is To, the predetermined rotation angle is θo, and a natural number is n, the following equation is established: Rotating body drive control device.
n × Tr = To × (θo / 2π) The rotary body drive control device according to any one of claims 7 to 10 ,
The control means, after starting the control of the rotational drive source based on the amplitude and phase of the rotational speed fluctuation, measures the rotational time, and on the basis of the measurement result, the rotational speed of one rotation cycle of the controlled object rotating body. A rotating body drive control device characterized by obtaining an amplitude or phase of a rotational speed fluctuation and correcting the amplitude and phase of the rotational speed fluctuation used for controlling the rotational drive source based on the amplitude or phase. In the rotating body drive control device according to any one of claims 7 to 11 ,
The rotating body drive control device, wherein the predetermined rotation angle is π [rad]. In the rotating body drive control device according to any one of claims 7 to 12 ,
The second detection means includes a rod-shaped member having a central portion in the longitudinal direction attached to the rotation axis of the rotating body to be controlled and having a detected portion at the longitudinal end portion, and a position where the detected portion of the rod-shaped member passes. A rotating body drive control device comprising: a detection device that detects the detected portion. A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
  Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
  The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The second detection means includes a rod-shaped member having a central portion in the longitudinal direction attached to the rotation axis of the rotating body to be controlled and having a detected portion at a longitudinal end, and a position where the detected portion of the rod-shaped member passes. A rotating body drive control device comprising: a detection device that detects the detected portion. In the rotating body drive control device according to any one of claims 7 to 12 ,
The second detection means includes a plate-like member having a center part attached to the rotation shaft of the controlled object rotating body and having a detected part in a part of the rotation direction at a position away from the center part, and the plate-like member A rotating body drive control device comprising: a detecting device that detects the detected portion at a position through which the detected portion passes. A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
  Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
  The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The second detection means includes a plate-like member having a center portion attached to the rotation shaft of the controlled object rotating body and having a detected portion at a part of the rotation direction at a position away from the center portion, and the plate-like member A rotating body drive control device comprising: a detecting device that detects the detected portion at a position through which the detected portion passes. In the rotating body drive control device according to any one of claims 7 to 12 ,
The second detection means includes a detection unit provided in a part of the rotation direction on the outer peripheral surface of the control target rotating body, and a detection device that detects the detection unit at a position where the detection unit passes. A rotating body drive control device, characterized in that it is configured by using. A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
  Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
  The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The second detection means includes a detection unit provided in a part of the rotation direction on the outer peripheral surface of the control target rotating body, and a detection device that detects the detection unit at a position where the detection unit passes. A rotating body drive control device, characterized in that it is configured by using. In the rotating body drive control device according to any one of claims 7 to 12 ,
The second detection means detects the detected portion at a position where the detected portion is formed by notching a part of the rotation direction of the rotating shaft of the control target rotating body, and the position where the detected portion passes. A rotating body drive control device comprising a detection device. A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
  Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
  The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The second detection means detects the detected portion at a position where the detected portion is formed by notching a part of the rotation direction of the rotation axis of the rotating body to be controlled, and the position where the detected portion passes. A rotating body drive control device comprising a detection device. The rotating body drive control device according to any one of claims 13 to 20 ,
A rotating body drive control device, wherein the detection device is provided at a plurality of locations separated by equal angles in the rotation direction of the detected portion. The rotating body drive control device according to any one of claims 13 to 20 ,
A rotating body drive control device, wherein a plurality of the detected parts are provided so as to be spaced apart at equal angles in the rotation direction. The rotating body drive control device according to claim 22 ,
A rotating body drive control device, wherein one of the plurality of detected parts is provided so as to be distinguishable from other detected parts. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and a visible image on the latent image carrier An image forming apparatus comprising a transfer means for transferring to a material,
An image forming apparatus comprising the rotating body drive control device according to any one of claims 7 to 23 as a rotating body drive control device that controls the rotation of the latent image carrier. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing the latent image on the latent image carrier, and a visible image on the latent image carrier An image forming apparatus comprising transfer means for transferring to a material, and an endless belt member that is stretched around a plurality of support rotating members,
The rotating body drive control device according to any one of claims 7 to 23 is provided as a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body among the plurality of supporting rotating bodies. A featured image forming apparatus. The image forming apparatus according to claim 25 .
The second detection means detects, instead of detecting that the drive rotator rotates a predetermined rotation angle, a driven rotator that follows the belt body among the plurality of support rotators rotates a predetermined rotation angle. An image forming apparatus for detecting the above. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and a visible image on the latent image carrier In an image forming apparatus comprising a transfer means for transferring to a material and an endless belt member that is stretched around a plurality of support rotating members,
As a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body among the plurality of supporting rotating bodies,
A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
Instead of detecting that the drive rotator rotates at a predetermined rotation angle, the second detection means rotates a driven rotator that follows the belt body among the plurality of support rotators at a predetermined rotation angle. An image forming apparatus comprising a rotating body drive control device for detecting the above. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing the latent image on the latent image carrier, and a visible image on the latent image carrier An image forming apparatus comprising transfer means for transferring to a material, and an endless belt member that is stretched around a plurality of support rotating members,
An image forming apparatus comprising the rotating body drive control device according to any one of claims 7 to 23 as a rotating body drive control device for controlling the rotation of the belt body. The image forming apparatus according to claim 26 or 27 .
The predetermined rotation angle is a rotation angle corresponding to one natural rotation of a half circumference of the belt body,
An image forming apparatus, wherein a detected portion for detecting rotation of the predetermined rotation angle is provided on the belt body. The image forming apparatus according to claim 26 or 27 .
The predetermined rotation angle is a rotation angle corresponding to one natural rotation of a half circumference of the belt body,
The rotation period of one driven rotating body that follows the belt body among the plurality of supporting rotating bodies is a natural fraction of the rotation period of the belt body,
2. The image forming apparatus according to claim 1, wherein the second detecting means is configured to detect that the belt body rotates the predetermined rotation angle by detecting one rotation of the driven rotating body. The image forming apparatus according to claim 26 or 27 .
The first detection means is configured to detect the rotational angular displacement of one driven rotating body that follows the belt body among the plurality of supporting rotating bodies, instead of the rotational angular displacement or rotational angular velocity of the rotation shaft of the rotational drive source. Configure to detect the angular velocity,
2. The image forming apparatus according to claim 1, wherein the second detecting means is configured to detect that the belt body rotates at the predetermined rotation angle by detecting rotation of another driven rotating body. The image forming apparatus according to claim 25 or 31,
The transfer unit is configured to transfer the visible image on the latent image carrier to a transfer material via an intermediate transfer member;
An image forming apparatus, wherein the belt member is the intermediate transfer member. 25. The image forming apparatus according to claim 24 .
A plurality of the latent image carriers are arranged so as to be aligned along the surface movement direction of the transfer material,
The control means obtains the amplitude and phase of the rotational speed fluctuation in one rotation cycle of each latent image carrier, and based on the amplitude and phase of the rotational speed fluctuation, each latent image carrier for the same location on the transfer material An image forming apparatus that controls a rotational drive source corresponding to each latent image carrier so that fluctuations in rotational speed of the same are in the same condition. The image forming apparatus according to claim 32 .
A plurality of the latent image carriers are disposed along the surface movement direction of the intermediate transfer member,
A drive transmission rotating body that transmits the rotational driving force of the drive source to the intermediate transfer body;
2. An image forming apparatus according to claim 1, wherein the rotation cycle of the drive transmission rotating member is equal to a time during which the surface of the intermediate transfer member passes the pitch between the latent image carriers. The image forming apparatus according to claim 32 .
A plurality of the latent image carriers are disposed along the surface movement direction of the intermediate transfer member,
A drive transmission rotating body that transmits the rotational driving force of the drive source to the intermediate transfer body;
The rotation cycle of the drive transmission rotator is equal to the time required for the surface of the intermediate transfer member to move from the primary transfer position facing the latent image carrier to the secondary transfer position facing the transfer material. Image forming apparatus. The image forming apparatus according to claim 24 or 35,
Drive transmission means for transmitting the rotational driving force of the driving source to the controlled object rotating body;
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. An image forming apparatus configured to detect a displacement or a rotational angular velocity. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing a latent image on the latent image carrier, and a visible image on the latent image carrier In an image forming apparatus provided with a transfer means for transferring to a material,
As a rotating body drive control device for controlling the rotation of the latent image carrier,
  A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation in one rotational period of the controlled rotating body are obtained based on the measurement result of each rotational time. A rotating body drive control device comprising a control means for controlling a rotation drive source,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. An image forming apparatus comprising a rotating body drive control device configured to detect a displacement or a rotational angular velocity. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing the latent image on the latent image carrier, and a visible image on the latent image carrier In an image forming apparatus comprising a transfer means for transferring to a material and an endless belt member that is stretched around a plurality of support rotating members,
As a rotating body drive control device for controlling the rotation of a driving rotating body for driving the belt body among the plurality of supporting rotating bodies ,
A rotation drive source, a drive transmission rotator for transmitting a rotation drive force of the rotation drive source to a control target rotator, and a first detection means for detecting a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device for controlling the rotation of the controlled rotating body by controlling the rotation driving source based on the detection result of the first detecting means,
Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation in one rotational period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. An image forming apparatus comprising a rotating body drive control device configured to detect a displacement or a rotational angular velocity. A latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier, a developing unit for developing the latent image on the latent image carrier, and a visible image on the latent image carrier In an image forming apparatus comprising a transfer means for transferring to a material and an endless belt member that is stretched around a plurality of support rotating members,
As a rotating body drive control device for controlling the rotation of the belt body,
A rotation drive source, a drive transmission rotator that transmits a rotation drive force of the rotation drive source to a control target rotator, and a first detection unit that detects a rotation angle displacement or a rotation angular velocity of a rotation shaft of the rotation drive source; A rotating body drive control device that controls the rotation of the rotating body to be controlled by controlling the rotation driving source based on the detection result of the first detecting means,
Second detection means for detecting that the controlled object rotating body rotates a predetermined rotation angle;
The rotational drive source is controlled by two or more types of control patterns having different driving conditions, and the control target rotator rotates a predetermined rotational angle based on the detection result of the second detection means at the time of control by each control pattern. Rotational time is measured, and the amplitude and phase of the rotational speed fluctuation of one rotation period of the controlled rotating body are obtained based on the measurement result of each rotational time, and the rotational speed fluctuation is calculated based on the amplitude and phase of the rotational speed fluctuation. A control means for controlling the rotational drive source,
The first detection means is configured to detect the rotation angle of the output shaft of the speed increasing mechanism including a gear provided on the rotation shaft of the rotating body to be controlled instead of the rotation angle displacement or the rotation angular velocity of the rotation shaft of the rotation drive source. An image forming apparatus comprising a rotating body drive control device configured to detect a displacement or a rotational angular velocity. A process cartridge used in the image forming apparatus according to claim 24 or 33 ,
A process cartridge comprising the above-described rotating body to be controlled and the above-described rotating body drive control device and configured to be detachable from the main body of the image forming apparatus . A rotational angular displacement or a rotational angular velocity of a rotational shaft of a rotational drive source that generates a rotational driving force transmitted to the controlled rotational body through a plurality of drive transmission rotational bodies is detected, and the rotational drive source is based on the detection result. A program used in a computer constituting a rotating body drive control device that controls the rotation of the controlled rotating body by controlling
Controlling the rotational drive source with two or more control patterns having different drive conditions;
At the time of control by each control pattern, at least one of the plurality of drive transmission rotators at a position other than the rotation axis of the control target rotator together with a rotation time when the control rotator rotates at a predetermined rotation angle. Measuring a rotation time when the drive transmission rotating body rotates a predetermined rotation angle;
Obtaining the amplitude and phase of the rotational speed fluctuation in one rotation period of the control object rotator and the drive transmission rotator to be measured based on the measurement results of these rotation times ;
A program for causing a computer to execute the step of controlling the rotational drive source based on the amplitude and phase of rotational speed fluctuations of the controlled object rotating body and the drive transmission rotating body to be measured . 42. The program of claim 41 , wherein:
A program for performing measurement of the rotation time and control of the rotation drive source based on the amplitude and phase in order from the one having the larger rotation cycle of the plurality of rotating bodies that are the measurement objects of the rotation time. In the program according to claim 41 or 42 ,
After starting the control of the rotational drive source based on the amplitude and phase of the rotational speed variation, the step of measuring the rotational time, and the rotational speed variation of one rotation period of the controlled rotating body based on the measurement result A program for causing a computer to execute the steps of obtaining the amplitude or phase of the rotation speed and correcting the amplitude and phase of the rotational speed fluctuation used for controlling the rotational drive source based on the amplitude or phase. By detecting the rotational angular displacement or rotational angular velocity of the rotational shaft of the rotational driving source that generates the rotational driving force transmitted to the controlled object rotating body, and controlling the rotational driving source based on the detection result, the controlled object A recording medium on which a program used in a computer constituting a rotating body drive control device for controlling rotation of a rotating body is recorded,
44. A recording medium, wherein the program is any one of claims 41 to 43 .