JP5262427B2 - Rotating body driving device, image forming apparatus, rotating body drive control method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain stable rotation of a photoreceptor drum by controlling periodic speed variation of the photoreceptor drum. <P>SOLUTION: The rotator driving device includes a rotator, a driving means for rotating and driving the rotator, a rotational speed-detecting means for detecting the rotational speed of the rotator, and a storing means for storing rotational speed information obtained when the rotator is driven at a constant speed each predetermined rotation phase interval until the past n circumferences. Median filter processing 64 is applied to the rotational speed information by n circumferences stored in the storing means 62 each predetermined rotation phase interval, an antiphase waveform rotational speed command value 66 for canceling the speed variation with respect to the linear speed (DC component) of the rotator 43 of rotational speed data is created by antiphase waveform creating processing 65, and the driving means is controlled based on the command value. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a rotating body driving device having a function of controlling the rotational speed of a rotating body, a copier, a facsimile, a printer, a plotter using the rotating body driving device, and a digital multifunction machine having these functions combined. The present invention relates to an image forming apparatus, a rotary drive apparatus, a rotating body drive control method implemented by the image forming apparatus, and a computer program for executing the rotary body drive control method by a computer.

  In a printing apparatus such as an electrophotographic copying machine or printer, a photosensitive drum having a cylindrical shape is used. This photosensitive drum needs to be rotated at a constant speed in order to accurately realize the image exposure position and the transfer position of the toner image onto the transfer belt. In particular, in the case of a tandem type image forming apparatus that forms a color image using four photosensitive drums, the accuracy of the transfer position is directly related to the image quality of the color image as a color shift amount. However, in the photosensitive drum, rotational speed fluctuations occur due to the eccentricity of the photosensitive drum gear, the driving shaft of the photosensitive drum motor, the load from the peripheral unit, resonance, and the like. Therefore, it is necessary to perform rotation speed control that suppresses fluctuations in the rotation speed and rotates the photosensitive drum at a constant speed.

  Feed-forward control is known as control for suppressing a periodic rotational speed fluctuation in one rotation of a rotating body such as a photosensitive drum. However, in such feed-forward control, when sudden fluctuations in rotational speed due to loads or resonances from peripheral units are handled as rotational speed data, the sudden rotational speed fluctuation is controlled. This will have an adverse effect on the rotation of the photosensitive drum. For this reason, it is necessary to control only periodic rotational speed fluctuations caused by the eccentricity of the drive shafts of the photosensitive drum gear and the photosensitive drum motor.

  As the rotation speed control, for example, the inventions described in Patent Documents 1 to 3 are known. Among them, Patent Document 1 discloses a rotation speed detected by the rotation detection means when the rotation detection means for detecting the rotation speed of the rotation body and the drive means for rotating the rotation body are driven at a constant speed. Storage means for storing information for each predetermined division section, and rotation speed information obtained by averaging the rotation speed information of the rotation detection means stored in the storage means by weighting according to the division section during operation of the imaging device And a control means for controlling the driving of the rotating body based on the above. In this invention, rotational speed data from which noise has been removed using moving average filter processing is stored in a storage device, and the angular speed of the drive motor is changed in accordance with the change in rotational speed.

  In Patent Document 2, in a rotating body drive mechanism including a rotating body, a driving unit that rotationally drives the rotating body, and a control unit that controls the rotation speed of the driving unit, the control unit rotates the rotating body. An invention is described in which the rotational speed of the driving means is controlled by synthesizing a constant rotational speed command value and at least one continuous repetition function value so that the speed is in a predetermined rotational state. . In the present invention, periodic fluctuations due to the eccentricity of the rotating body are expressed by a continuous repetition function, and this reverse phase waveform is used as a drive command value for the driving means to obtain smooth rotation and control to cancel the fluctuations. Like to do.

In Patent Document 3, a control unit that controls the rotation speed of the image carrier, a detection unit that detects the rotation speed, a storage unit that stores the rotation speed until n rotations of the image carrier, and a rotation cycle. A determination unit that determines whether or not a difference in rotation speed between the latest rotation speed and the rotation speed before the previous n cycles is equal to or greater than a predetermined reference value at the same position and the vicinity thereof. In the image forming apparatus that controls the rotation speed of the image carrier using the rotation speed data in a predetermined section including the same rotation position of the rotation cycle before one rotation or before n rotations, the determination result of the determination unit Accordingly, the rotation speed of the next rotation cycle is controlled to control the image carrier to a stable rotation speed. Specifically, in order to eliminate the effects of sudden fluctuations in rotational speed, the rotational speed data for the past five laps are compared with the latest data. Measures are taken to remove and output the average value of the data group below the threshold.
JP 07-303385 A JP 2005-176467 A JP 2006-235577 A

  However, in the invention described in Patent Document 1, due to the characteristics of the moving average filter, it is easily affected by sudden rotation speed fluctuations caused by loads, resonances, and the like from peripheral units. Further, in the invention described in Patent Document 2, since rotational speed fluctuations other than a specific period are not controlled, there is no influence of sudden rotational speed fluctuations, but rotational speeds of a period caused by eccentricity of the drive shaft of the drum motor. Variations cannot be controlled. Furthermore, since the average value is adopted in the invention described in Patent Document 3, it is easily affected by sudden speed fluctuations less than a threshold and noise caused by loads, resonances, and the like from peripheral units. Therefore, it is not an essential solution to the problem. When the drum operates at almost the same speed fluctuation every revolution, that is, when the repeatability of rotation is good, the expected control result is obtained, but when repeatability is poor. However, the control accuracy decreases.

  On the other hand, when the toner image on the photosensitive drum is transferred onto the transfer belt, the transfer belt and the photosensitive drum are brought into contact with each other by a transfer device. When the photosensitive drum is rotated in this state, sudden speed fluctuations and noise are generated in the rotation speed data due to the load from the transfer belt, and the rotation repeatability is deteriorated. When the above-described rotation control is performed based on such rotation speed data, the control accuracy is deteriorated.

  On the other hand, in the rotational speed data of the photosensitive drum, sudden speed fluctuations may occur due to load fluctuations of peripheral units regardless of whether the transfer belt is in contact or not. Control of such speed fluctuations as rotational speed data also causes deterioration in control accuracy.

  In any case, it is difficult to suppress speed fluctuation when sudden speed fluctuation or noise occurs. In the invention described in each cited document, the speed fluctuation is accurately controlled when sudden speed fluctuation or noise occurs. I can't.

  Therefore, the problem to be solved by the present invention is to obtain a stable rotation of the rotating body by controlling the periodic speed fluctuation of the rotating body without being affected by noise and sudden speed fluctuation.

In order to achieve the above object, the present invention provides a rotating body, driving means for rotationally driving the rotating body, rotational speed detecting means for detecting the rotational speed of the rotating body, and driving the rotating body at a constant speed. past n orbiting rotational speed information obtained for each predetermined rotational phase interval when: a storage means for storing up to (n n ≧ 1 integer), the rotary body drive system that having a, stored in said storage means Control means for controlling the rotational speed by applying a median filter for each predetermined rotational phase interval for rotational speed information for n revolutions , and the storage means includes rotational phase intervals before and after the rotational phase interval. In addition to the rotational speed information for the past n revolutions, the rotational speed information for two sections before and after the rotational speed information is stored, and when the median filter is applied, the control means stores the rotational speed information in the rotational phase section. Before Rotation speed information of the rotational phase interval of two sections characterized in that it also be subject to the median filter.

  In the embodiment described later, the rotating body is the photosensitive drums 11y, 11m, 11c, and 11k, the driving means is the reference numeral 41, the rotational speed detecting means is the encoder 50 and the control means 45, and the storage means is the reference numeral 62. The median filter corresponds to the median filter processing 64, the control unit corresponds to the calculation unit 47 and the control unit 45, the transfer belt corresponds to the reference numeral 21, and the contact roller corresponds to the reference numerals 22y, 22m, 22c, and 22k.

ADVANTAGE OF THE INVENTION According to this invention, the periodic speed fluctuation | variation of a rotary body can be suppressed without being influenced by noise and sudden speed fluctuation, and the rotation of a rotary body can be obtained stably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of a four-color full-color image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to the present embodiment is a so-called indirect transfer tandem image forming apparatus. In the figure, the image forming apparatus has four photosensitive drums 11y, 11m, 11c, and 11k, and forms a toner image of each color on each of the photosensitive drums 11y, 11m, 11c, and 11k. Image forming units 1y, 1m, 1c, and 1k for the respective colors are provided on the outer peripheral portions of the photosensitive drums 11y, 11m, 11c, and 11k, respectively. The image forming units 1y, 1m, 1c, and 1k for each color include drum chargers 12y, 12m, 12c, and 12k, exposure devices 13y, 13m, 13c, and 13k, developing units 14y, 14m, 14c, and 14k, and transfer units for each color. 15y, 15m, 15c, 15k, and drum cleaning devices 16y, 16m, 16c, 16k, respectively. In the image forming units 1y, 1m, 1c, and 1k, toner images of different colors are formed such that 1y is yellow, 1m is magenta, 1c is cyan, and 1k is black. A transfer belt 21 is provided to superimpose these toner images. When transferring the toner image, contact rollers 22y, 22m, 22c, and 22k are provided to bring the transfer belt 21 into contact with the photosensitive drums 11y, 11m, 11c, and 11k. A belt driving motor 23 and a belt cleaning device 24 are disposed around the transfer belt 21. A secondary transfer device 31 is provided at a position facing the lower end of the transfer belt 21, and a paper transport path 33 is provided so that the paper 32 passes between the secondary transfer device 31 and the transfer belt 21. In addition, a fixing device 34 is provided after passing between the secondary transfer device 31 and the transfer belt 21 (downstream in the paper transport direction).

The toner image forming process in each of the image forming units 1y to 1k will be described by taking a yellow toner image forming process as an example.
When the photosensitive drum 11y starts rotating, a high voltage is applied to the drum charger 12y, and negative charges are uniformly charged on the surface of the photosensitive drum 11y. Further, the contact roller 22y moves upward, and the transfer belt 21 contacts the photosensitive drum 11y. Next, when image information is transmitted from a controller (not shown) to the image forming apparatus, the exposure device 13y controls on / off of the light emission signal in accordance with the image information. As a result, a portion irradiated with laser light from the exposure device 13y and a portion not irradiated with light from the exposure device 13y are formed on the surface of the photosensitive drum 11y, and negative charges are reduced in the portion irradiated with the laser light.

  When the portion where the charge is reduced on the photosensitive drum 11y reaches a position facing the developing device 14y, toner charged to a negative charge is attached to the portion where the electrification is reduced on the photosensitive drum 11y, and toner development is performed. A toner image is formed.

  When the toner image formed on the photosensitive drum 11y reaches a position where it abuts on the transfer belt 21, the toner image is primarily transferred onto the transfer belt 21 by the action of a high voltage applied to the transfer device 15y. Thereafter, the photosensitive drum 11y that has passed through the portion in contact with the transfer belt 21 passes through the drum cleaning device 16y, and the toner remaining on the surface of the photosensitive drum 11y is removed.

  For other colors, toner images are formed on the respective photoconductive drums 11m, 11c, and 11k in the same process, and the toner images are transferred onto the transfer belt 21 so as to overlap with each other, and the four color toner images are superimposed. An image is formed.

  The transfer belt 21 is conveyed in the direction of arrow A by a belt drive motor 23. At the same time when the full-color image formed on the transfer belt 21 reaches the portion facing the secondary transfer device 31, the sheet 32 is an example of a sheet-like medium that has been conveyed through the sheet conveyance path 33 in the arrow B direction. Reaches the secondary transfer unit 31. Then, the full color image is transferred onto the paper 32 by the action of the high voltage applied to the secondary transfer device 31.

  The full color image transferred onto the paper 32 is melted and fixed when the paper 32 passes through the fixing device 34. On the other hand, the transfer belt 21 that has passed through the portion facing the secondary transfer device 31 passes through the belt cleaning device 24, and the toner remaining on the surface of the transfer belt 21 is removed.

  As described above, in the full-color image forming apparatus, a single-color toner image is formed on the photosensitive drums 11y, 11m, 11c, and 11k for each color, and then the full-color image is formed by superimposing the toner images on the transfer belt 21. doing. For this reason, if the rotation of the photosensitive drums 11y, 11m, 11c, and 11k includes a speed variation, the toner images cannot be accurately superimposed, and color misregistration may occur in the formed image. This color shift appears as a reduction in image quality. Therefore, in the present embodiment, it is intended to suppress fluctuations in the rotational speed of the photoconductive drums 11y, 11m, 11c, and 11k, and prevent a color shift of the formed image so that a high-quality full color image can be obtained. .

  FIG. 2 is a diagram showing a schematic configuration of the rotating body driving device in the present embodiment. In FIG. 2, the rotating body driving device 40 includes a driving means 41, a rotation transmitting means 42, a rotating body 43, a rotation speed detecting means 44 a or 44 b, a control means 45, a storage means 46, and a computing means 47. Prepare.

  Various motors such as a stepping motor, a DC brushless motor, a DC servo motor, and an AC servo motor can be used as the driving means 41. The rotation transmitting means 42 is a mechanism for transmitting the rotational power of the driving means to the rotating body 43 using a geared motor shaft, gear, or the like. The rotating body 43 is a rotating unit such as the photosensitive drums 11y, 11m, 11c, and 11k and a photosensitive drum driving shaft. A configuration may be adopted in which a stable rotation is obtained by adding a flywheel or the like to the photosensitive drum drive shaft.

  The rotational speed detecting means 44a or 44b is a rotary encoder 50 for detecting a slit 52 of a code wheel 51 provided on a photosensitive drum drive shaft 43a as shown in FIG. In order to improve the rotational speed detection accuracy, the first rotational speed detecting means 44a and the second rotational speed detecting means 44b are arranged opposite to each other, and the respective encoder output intervals are averaged to reduce the eccentric component of the code wheel. You may let them. The control means 45 is composed of an embedded processor, FPGA, dedicated IC or the like, and is determined by the calculation means 47 and a function for storing the detected rotational speed data from the first and second speed detection means 44a, 44b in the storage means 46. And a function of outputting a signal to the driving means 41 in accordance with the rotation speed command value. The storage means 46 is composed of a volatile memory IC such as SRAM, and stores the detected rotational speed data from the first and second speed detecting means 44a and 44b as described above. The calculation means 47 is composed of an embedded processor, FPGA or the like, and generates a rotation speed command value 66 (see FIG. 4) from the rotation speed data stored in the storage means 46, and passes the rotation speed command value to the control means 45. have.

  Hereinafter, Example 1 of the present embodiment will be described.

  FIG. 4 is a block diagram showing a processing configuration of the calculation means 47 for creating the rotation speed command value. In the present embodiment, the first and second reception interval times 61a and 61b obtained from the first and second rotation speed detection means 44a and 44b (shown as reception interval time 1 and reception interval time 2 in FIG. 4). As processing units for processing, a storage means 62, a low-pass filter process 63, a median filter process 64, and an antiphase waveform generation process 65 are included. And the rotational speed command value 66 which suppresses the rotational speed fluctuation | variation of the rotary body 43 through each process unit is obtained. As will be described later, the rotation speed command value 66 is generated by the calculation means 47 and sent to the control means 45. By sending the rotation speed command value 66 from the control means 45 to the drive means 41, the rotation speed of the rotating body 43 is increased. Is controlled.

  First, regarding the details of the method for obtaining the first and second reception interval times 61a and 61b and the method for storing the rotational speed data, the first and second rotational speed detecting means 44a and 44b are arranged opposite to each other as shown in FIG. This will be described based on the example.

  The code wheel 51 of the rotary encoder 50 is provided with slits 52 at equal intervals. When the slit 52 reaches the opposing portion of the first and second rotation speed detection means 44a and 44b, detection signals are transmitted from the first and second rotation speed detection means 44a and 44b to the control means 45, respectively. . The control means 45 measures the reception interval time of the detection signal, and saves the reception interval time in the storage means 62 every time the detection signal for the number of slits included in the rotation phase section 53 of the rotating body 43 is received. At that time, by adopting an average value of the first reception interval time 61a from the first rotation speed detection means 44a and the second reception interval time 61b from the second rotation speed detection means 44b, the code wheel 51 The eccentric component of is removed.

  Next, the computing unit 47 reduces the noise in the rotational speed data by performing a low-pass filter process 63 on the rotational speed data stored in the storage unit 62. At this time, the cut-off frequency and attenuation amount of the low-pass filter are determined so as to correct the rotational speed fluctuation of the period caused by the eccentricity of the drive shaft of the drive means 41.

  After the processing of the low-pass filter processing 63, the calculation means 47 applies the median filter processing 64 to the rotation speed data for n rotations for each rotation phase section of the rotator 43, thereby causing sudden rotation speed fluctuations. Suppress. As shown in FIG. 5, the median filter is a filter that rearranges the input data group in ascending order of values (large) and outputs a median value. When the median filter process 64 is performed, the filter output waveform is smoothed by performing the median filter process with the data of the preceding and subsequent rotational phase sections as shown in FIG. However, since the number of data to be input to the median filter is insufficient when processing the data of the end rotational phase section, for example, when processing the data of the first rotational phase section of the m-th rotation, m−1. When processing the data of the last rotation phase interval of the rotation and the data of the last rotation phase interval of the m rotation, the data is processed using the data of the first rotation phase interval of the (m + 1) th rotation. At this time, since the information is insufficient with only the rotation speed data for n rotations, data for two sections before and after are further stored in addition to the rotation speed data for n rotations. That is, when the median is obtained from the phase interval indicated by the dotted line as shown in FIG. 6, the phase data before and after the phase interval is used as surrounded by the one-dot chain line, and the number of data in the phase interval is If the number is n, the median filtering process performs filtering with n × 3 data.

  Finally, as shown in FIG. 7, the anti-phase waveform generation processing 65 generates an anti-phase waveform rotational speed command value 66 that cancels the speed fluctuation of the rotational speed data with respect to the linear speed (DC component) of the rotating body 43. To the control means 45. The control means 45 can suppress fluctuations in the rotational speed of the rotating body 43 by operating the drive means 41 based on the rotational speed command value 66.

  In the diagram shown in FIG. 7, the horizontal axis represents the rotational phase interval number and the vertical axis represents the rotational speed fluctuation rate. The solid line represents rotational speed data, and the broken line represents rotational speed command value data. This rotational speed command value data is a rotational speed command value 66 having a waveform with an opposite phase to the rotational speed.

  By obtaining the rotational speed command value in this way, it is possible to suppress the rotational speed fluctuations of the photoconductive drums 11y, 11m, 11c, and 11k, prevent color shift of the formed image, and obtain a high-quality full-color image.

  In the first embodiment, when the rotation speed command value 66 is generated as shown in FIG. 4, it is necessary to acquire the rotation speed data of the rotating body 43 using the encoder 50. When this is applied to the image forming apparatus of FIG. 1, it is necessary to rotate the photosensitive drums 11y, 11m, 11c, and 11k corresponding to the rotating body 43. Usually, the photosensitive drums 11y, 11m, 11c, and 11k are brought into contact with the transfer drum 21 by the contact rollers 22y, 22m, 22c, and 22k in order to transfer the toner image. It rotates in the state. In this case, as shown in FIG. 8, sudden speed fluctuations and noise frequently occur in the transfer belt 21 due to disturbance from the transfer belt unit including a driving mechanism for driving the transfer unit 21, and the rotation is repeated. Sexuality will deteriorate. On the other hand, when the photosensitive drums 11y, 11m, 11c, and 11k and the transfer belt 21 are rotated apart from each other, sudden speed fluctuations and noise are small as shown in FIG. 9, and rotation repeatability is good.

  Therefore, in the second embodiment, as shown in the timing chart of FIG. 10, when the rotational speed data is measured, the measurement is performed in a state where the photosensitive drums 11y, 11m, 11c, and 11k and the transfer belt 21 are separated from each other. That is, the transfer belt 21 is activated upon completion of the measurement of the rotation speed data, and the transfer belt 21 is brought into contact with the photosensitive drums 11y, 11m, 11c, and 11k by the contact rollers 22y, 22m, 22c, and 22k. Thereafter, the photosensitive drums 11y, 11m, 11c, and 11k are driven with the rotational speed command value 66 obtained from the rotational speed data at the time of separation, so that the rotational speeds of the photosensitive drums 11y, 11m, 11c, and 11k are made constant. Can keep.

  More specifically, in FIG. 10, the photosensitive drums 11y, 11m, 11c, and 11k, the transfer belt 21, and the contact rollers 22y, 22m, 22c, and 22k are stopped driving, that is, the transfer belt 21 is in the photosensitive drum 11y. First, the photosensitive drums 11y, 11m, 11c, and 11k are activated (T1) from a state where they are separated from 11m, 11c, and 11k, and after reaching a steady speed (T2), rotation speed measurement S1 is started (T3). ). When the rotation speed measurement is completed, the transfer belt 21 starts to rotate (T4). When the predetermined rotation speed is reached (T5), the contact rollers 22y, 22m, 22c, and 22k are driven to transfer. The belt 21 is brought into contact with the photosensitive drums 11y, 11m, 11c, and 11k (T6), and the images of the respective colors are transferred to the transfer belt 21. During this time, the median filter process S2 is executed on the photosensitive drums 11y, 11m, 11c, and 11k. Other parts not specifically described are configured in the same manner as in the first embodiment and function in the same manner.

  By performing the median filter processing S2 at such timing and obtaining the rotation speed command value, fluctuations in the rotation speed of the photoconductive drums 11y, 11m, 11c, and 11k are suppressed, and color deviation of the formed image is prevented and high image quality is achieved. A full-color image can be obtained.

  As described above, according to the present embodiment, the feedforward control is performed using the rotational speed data obtained from the encoder 50, so that the photosensitive drum gear among the speed fluctuations of the photosensitive drums 11y, 11m, 11c, and 11k. In addition, it is possible to selectively control only the speed fluctuation having periodicity due to the eccentricity of the drive shaft of the photosensitive drum motor or the like. That is, by removing only noise without periodicity and sudden speed fluctuations, it is possible to prevent deterioration of control accuracy and stably produce high-quality full-color images.

  In this embodiment, the photosensitive drums 11y, 11m, 11c, and 11k are taken as examples of the rotating body. However, the present invention is applicable to any rotating body that functions as a driving source for driving other members. The present invention is not limited to this embodiment, and all technical matters included in the technical idea described in the scope of claims are targeted.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows schematic structure of the rotary body drive device which concerns on embodiment of this invention. It is a figure which shows the rotational speed data measurement mechanism (encoder) which concerns on embodiment of this invention. It is a block diagram which shows the structure which produces | generates the rotational speed command value in Example 1. FIG. It is a figure which shows the outline | summary of the median value filter process used in Example 1. FIG. 6 is a diagram illustrating input data for median filter processing in Embodiment 1. FIG. It is a figure which shows the rotational speed command value data output to a control means from a calculating means. FIG. 6 is a diagram illustrating rotation speed data of a photosensitive drum when the photosensitive drum and a transfer belt are brought into contact with each other and rotated. FIG. 6 is a diagram illustrating rotation speed data of a photosensitive drum when the photosensitive drum and the transfer belt are rotated apart from each other. FIG. 6 is a diagram illustrating an outline of operation timings of a photosensitive drum, a transfer belt, and a contact roller in Embodiment 2.

Explanation of symbols

11y, 11m, 11c, 11k Photosensitive drum 21 Transfer belt 22y, 22m, 22c, 22k Abutting roller 40 Rotating body driving device 41 Driving means 43 Rotating body 44a, 44b Rotating speed detecting means 45 Control means 47 Calculation means 50 Encoder 51 Code wheel 52 Slit 53 Rotation phase section 61a, 61b Reception interval time 62 Storage means 63 Low pass filter process 64 Median value filter process 65 Reverse phase waveform generation process 66 Rotational speed command value

Claims (7)

A rotating body,
Driving means for rotationally driving the rotating body;
Rotation speed detection means for detecting the rotation speed of the rotating body;
Storage means for storing rotational speed information obtained when the rotating body is driven at a constant speed up to the past n rounds (n: integer of n ≧ 1) for each predetermined rotational phase section;
The rotary member driving device that having a,
Control means for controlling the rotational speed by applying a median filter for each predetermined rotational phase interval to the rotational speed information for n revolutions stored in the storage means ;
The storage means stores rotational speed information for two sections before and after the rotational speed information in addition to rotational speed information for the past n revolutions in a rotational phase section before and after the rotational phase section,
The control means, when the median filter is applied, also applies rotational speed information of the rotational phase sections of the front and rear two sections to the rotational phase section as the application target of the median filter. apparatus. The rotating body drive device according to claim 1,
The rotating body drive device, wherein the rotating body is a photosensitive drum . An image forming apparatus comprising the rotating body driving device according to claim 2 . The image forming apparatus according to claim 3 .
A transfer belt for transferring a toner image from the photosensitive drum;
A contact roller for contacting the photosensitive drum and the transfer belt;
With
An image forming apparatus , wherein when the rotational speed information is stored in the storage unit, the contact between the photosensitive drum and the transfer belt is released . The image forming apparatus according to claim 4 .
The control means controls the rotational speed of the photosensitive drum based on the rotational speed information stored in the storage means when the contact is released when the photosensitive drum is brought into contact with the transfer belt. An image forming apparatus. A rotating body,
Driving means for rotationally driving the rotating body;
Rotation speed detection means for detecting the rotation speed of the rotating body;
Storage means for storing rotational speed information obtained when the rotating body is driven at a constant speed up to the past n rounds (n: integer of n ≧ 1) for each predetermined rotational phase section;
Control means for controlling the rotational speed by applying a median filter for each predetermined rotational phase interval to the rotational speed information for n revolutions stored in the storage means;
A rotating body drive control method for controlling the rotational speed of the rotating body of a rotating body drive device having
The storage means stores rotational speed information for two sections before and after the rotational speed information in addition to rotational speed information for the past n revolutions in the rotational phase section before and after the rotational phase section,
When the control means applies a median filter for each predetermined rotation phase interval to the rotation speed information for n revolutions stored in the storage means, the rotation of the two preceding and following intervals with respect to the rotation phase interval A rotational body drive control method, wherein rotational speed information of a phase section is also applied to a median filter to control the rotational speed . A rotating body,
Driving means for rotationally driving the rotating body;
Rotation speed detection means for detecting the rotation speed of the rotating body;
Storage means for storing rotational speed information obtained when the rotating body is driven at a constant speed up to the past n rounds (n: integer of n ≧ 1) for each predetermined rotational phase section;
Control means for controlling the rotational speed by applying a median filter for each predetermined rotational phase interval to the rotational speed information for n revolutions stored in the storage means;
A computer program for causing a computer to control the rotational speed of the rotating body of the rotating body drive device comprising :
The storage means stores in addition to the rotational speed information for the past n revolutions in the rotational phase section before and after the rotational phase section, and further stores rotational speed information for two sections before and after the rotational speed information;
When the control means applies a median filter for each predetermined rotation phase interval to the rotation speed information for n revolutions stored in the storage means, the rotation of the two preceding and following intervals with respect to the rotation phase interval The procedure for controlling the rotational speed as the application target of the median filter for the rotational speed information of the phase interval,
Computer program characterized by comprising a.