JP5061591B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that adjusts image formation by controlling the speed of a rotating body such as an image carrier for performing transfer. More specifically, the present invention relates to an image forming apparatus that controls the speed of a rotating body by measuring transfer characteristics.

  The image forming apparatus has a rotating body such as a photosensitive drum or an intermediate transfer belt for transferring an image. And in order to perform image formation correctly, it is necessary to adjust the rotational speed of this rotary body correctly. In order to accurately adjust the rotational speed in such a system that requires high-precision control for driving the rotating body, it is desirable to determine the control parameters after grasping the transfer characteristics of the drive system.

  Conventionally, in an image forming apparatus, a transfer characteristic is measured in advance using a prototype or the like, and a fixed control parameter determined based on the result is used. In particular, in a control system including repetitive control used when performing control with higher accuracy, the inverse characteristic of the drive system transfer characteristic (here, “inverse characteristic” is an inverse function of a function representing the transfer characteristic. ), The controllability is reduced when the difference between the control parameter and the actual device transfer characteristic is large. Therefore, normally, control parameters are set so as to achieve both control stability and controllability within a predictable change range of the transmission characteristics of the drive system. In practice, however, it is difficult to assume in advance the range of change in transfer characteristics, including changes over time and component variations, and widening the stable range of control increases the range that allows changes in the speed of the rotating body. Therefore, the accuracy of controllability is lowered. Therefore, it is very difficult to secure a stable range of high accuracy and wide control. Therefore, a technique for obtaining a transfer function in rotation control, obtaining a phase margin and a gain margin from the transfer function, and changing the control parameter if the obtained numerical value exceeds a value indicating a stable range (for example, patent document) 1), and even if one of the rotating members is replaced, a technology for newly obtaining the transfer function of the system by the speed detection means and resetting the control parameters (for example, see Patent Document 2) or , Memorize the speed fluctuation in one rotation of the rotating body in steady state, determine the dominant frequency component from the data, find the frequency response of the drive transmission system, calculate the response characteristics, and repeat control based on this Techniques to be performed (see, for example, Patent Document 3) have been proposed. With these control techniques, parameters are not set in advance using a test machine, but transmitted using actual signals in the actual machine. The characteristics are measured, it has been made to change the control parameters.

JP-A-6-175427 JP-A-8-220966 JP-A-9-182488

  With the above control, it is possible to calculate and change the control parameter using the actual signal. However, in the above control, the transfer characteristic is obtained from the control command value sent to the control system in the actual processing and the actual angular velocity detection result at that time. In this regard, in order to control the rotating body, since the rotating speed of the rotating body is slow, a low frequency signal around 2-3 Hz works most effectively. However, when a control command signal used for actual control is used for calculation, the SN ratio is poor at low frequency components and is difficult to use. Control parameters are calculated using transfer characteristics at input values of high frequency components. It will be. Therefore, the transfer characteristics that can be actually detected are limited, and it is difficult to obtain the required characteristics, and the accuracy of control using the control parameters calculated therefrom is lowered.

  The present invention has been made in view of such circumstances, and detects a transfer characteristic using a test signal including a low frequency to a high frequency, calculates a parameter for changing an inverse characteristic filter from the transfer characteristic, and is changed. Another object of the present invention is to provide an image forming apparatus that controls the rotation system using the inverse characteristic filter.

In order to achieve the above object, an image forming apparatus according to claim 1, a rotating body for transferring an image, a driving means for rotating the rotating body, and a control signal to the driving means, An image forming apparatus having a control means for controlling the speed of the rotating body, the test signal generating means generating a test signal including a frequency band of 2 Hz to 16 Hz , and adding the test signal to the control signal; An angular velocity detecting means for detecting the rotational angular velocity of the rotating body, and a transmission for obtaining the latest transfer function of the rotating system including the rotating body and the driving means based on the rotating angular velocity and the test signal from the angular velocity detecting means. Function calculating means, and the control means has the desired rotational angular velocity based on the inverse function of the transfer function of the rotating system corresponding to the desired rotational angular velocity and the inverse function of the latest transfer function. Like Further, the driving means is controlled.

A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the control unit includes an inverse characteristic filter based on an inverse function of the transfer function in advance, and a designated desired rotation speed. The repetitive control means for outputting the control signal obtained by passing the information in the reverse characteristic filter, the transfer function calculating means, based on the latest transfer function, the reverse characteristic filter A parameter value for changing to an inverse characteristic filter for a transfer function is calculated and transmitted to the repetition control unit, so that the information on the desired rotational angular velocity is transmitted to the repetition control unit. The control signal obtained by passing through an inverse characteristic filter including a value is output .

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, in addition to the control of the driving means by the control signal of the repeat control means, the information on the rotational angular velocity is received. And PI control means for performing proportional control and integral control.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the warning unit notifies the warning when the value of the transfer function exceeds a predetermined value. Is further provided.

  A fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the rotating body is a photosensitive drum or an intermediate transfer belt. is there.

  According to the image forming apparatus according to claim 1 and claim 2, since the transfer function is obtained using a test signal including a low frequency to a high frequency from the outside of the rotating body, a transfer function in a wide frequency band can be obtained. . Therefore, the calculation of parameters for changing the inverse characteristic filter that controls the repetitive fluctuation component of the rotating body by the transfer function obtained using the transfer characteristic of the low frequency component that strongly affects the rotation of the rotating body Is possible. In other words, since a more appropriate parameter value for changing the inverse characteristic filter that controls the repetitive fluctuation component of the rotating body can be calculated, the rotating body can be controlled with high accuracy, and an accurate image can be formed. .

  According to the image forming apparatus of claim 3, the repeatability of the rotating body is obtained by obtaining a parameter value for changing the inverse characteristic filter using a transfer function in a wide frequency band including a low frequency to a high frequency. By controlling a certain fluctuation component and performing feedback control, it is possible to control fine fluctuations and sudden fluctuations in the rotating body with different frequencies. Thereby, the rotating body can be controlled with higher accuracy, and an accurate image can be formed.

  According to the image forming apparatus of the fourth aspect, a warning is notified when the transfer function at a low frequency component exceeds a predetermined value. As a result, an abnormality is detected by a frequency component that greatly affects the speed of the rotating body, and an accurate abnormality can be detected.

  According to the image forming apparatus of the fifth aspect, the speed of the photosensitive drum or the intermediate transfer belt of the image forming apparatus can be adjusted with high accuracy. Thereby, accurate image formation becomes possible.

[First Embodiment]
The image forming apparatus according to the first embodiment will be described below. FIG. 1 is a block diagram showing functions of an image forming apparatus according to the present invention. FIG. 2 is a configuration diagram of the drive control device of the image forming apparatus according to the present invention. As shown in FIG. 1, the image apparatus according to the present invention includes a rotating body 1, a drive unit 2, a control unit 3, a transfer function calculation unit 4, a test signal generation unit 5, a rotation speed detection unit 6, and a warning unit 7. Prepare. Further, the control unit 3 includes a repetition control unit 31 and a PI control unit 32. Here, the control means 3, the transfer function calculation means 4, and the rotation speed detection means 6 are constituted by a CPU. Examples of the rotating body 1 include a photosensitive drum or an intermediate transfer belt. Hereinafter, the rotating body 1 will be described as a photosensitive drum.

The control means 3 calculates the control command signal for obtaining the target rotation angular velocity by the repetitive control means 31 passing the target rotation angular velocity of the rotating body 1 through the inverse characteristic filter. For example, if the target value is ω ₀ and the function representing the inverse characteristic filter is F ⁻¹ (x), the control command signal is F ⁻¹ (ω ₀ ). Here, the inverse characteristic filter is a filter representing the inverse characteristic of the transfer characteristic of the rotating system 8. The repetitive control means 31 can reduce periodic fluctuations among fluctuations in the rotational angular velocity of the rotating body 1 by controlling according to the period of the rotating body 1 (for example, once per rotation). it can.

The repetition control means 31 holds sampling data of the value of the rotational angular velocity for one rotation before one rotation. Then, the repetition control means 31 subtracts the target value ω ₀ from the rotational angular velocity (ω ₀ + Δω. Δω is the fluctuation amount) before one rotation, that is, performs (ω ₀ + Δω) −ω ₀ , A variation Δω, which is the difference between the rotational angular velocity before one rotation and the target rotational angular velocity, is calculated. Then, the variation Δω is passed through an inverse characteristic filter to obtain a control command signal F ⁻¹ (Δω) that is worth the variation. Then, the control command signal F ⁻¹ (ω ₀ ) before one rotation is subtracted from the control command signal F ⁻¹ (Δω) worthy of the fluctuation, and the control command signal F incorporating the fluctuation in the rotational angular velocity before one rotation is incorporated. ⁻¹ (ω ₀ ) −F ⁻¹ (Δω) is calculated. As a result, control is performed so that the rotational angular velocity before one rotation (ω ₀ + Δω) −the variation Δω = the target rotational angular velocity ω ₀ .

  Further, when changing the parameter (specifically, the parameter of the inverse function of the transfer function constituting the inverse characteristic filter) to change the inverse characteristic filter (hereinafter, sometimes referred to as “calibration of the inverse characteristic filter”), The repeat control means 31 receives the parameters such as the torque constant in the inverse function of the latest transfer function obtained by the transfer function calculation means 4 and the coefficient of the term representing the contact coefficient between the photosensitive drum and the intermediate transfer belt, and repeat control is performed. The inverse characteristic filter of the means 31 is changed. Here, the contact coefficient is a value indicating that the degree of adhesion between the photosensitive drum and the intermediate transfer belt increases as the value increases. Then, after changing the inverse characteristic filter, the repetition control means 31 calculates the control command signal described above. Hereinafter, “parameter” refers to a parameter for changing the inverse characteristic filter.

  Further, the PI control means 32 calculates a control command signal for adjusting to the target rotational angular velocity by performing proportional control and integral control based on the difference between the fed back rotational angular velocity and the target rotational angular velocity. Then, the control unit 3 transmits a control command signal obtained by adding the control command signal calculated by the PI control unit 32 to the control command signal calculated by the repetition control unit 31 to the driving unit 2.

  In this embodiment, in order to control the rotating system 8 more accurately, the control means 3 is provided with the repetition control means 31 and the PI control means 32. In principle, this is the repetition control means 31. Therefore, the PI control means 32 is not always necessary. The PI control means 32 is effective for suppressing fluctuations that do not depend on the periodicity of the rotating body 1.

  The driving unit 2 receives the control command signal transmitted from the control unit 3 and generates a rotational torque to rotate the rotating body 1. As shown in FIG. 2, actually, the rotational torque generated by the driving means 2 is transmitted to the rotating body 1 through the gear train.

  The toner image is transferred from the rotating body 1 serving as the photosensitive drum to the rotating intermediate transfer belt, and the image is further transferred from the intermediate transfer belt to the transfer paper.

  The test signal generation means 5 generates a test signal, places the test signal on a control command signal sent from the control means 3 to the drive means 2, and sends the test signal to the transfer function calculation means 4. Here, white noise including components from a low frequency to a high frequency is used for the test signal. Here, since the rotating body 1 has only a few rotations per second, a signal in a low frequency band greatly affects the rotational angular velocity of the rotating body 1, and therefore it is preferable to use white noise including a low frequency band. In particular, white noise including a frequency band in the range of 5 to 10 times the reference frequency (2 to 3 Hz in this embodiment) is preferable. Here, FIG. 3 which is a figure showing the control characteristic of the rotating system 8 is referred. In FIG. 3, the horizontal axis represents the frequency of the test signal input to the driving means 2, and the vertical axis represents the transmission ratio corresponding to the frequency of the test signal. Here, the transmission ratio is the ratio of the rotational angular velocity from the rotational speed detecting means 6 to the output value from the test signal generating means 5. In addition, FF in FIG. 3 is a curve of control characteristics of repetitive control, and FB is a curve of control characteristics of PI control. In FIG. 3, the smaller the value on the vertical axis, the more effective the control. For example, the control is very effective at the point 001, but the control is not effective at the point 002. This indicates that the point 001 where the control is effective corresponds to a cycle that is an integral multiple of one rotation of the rotator 1, and the control is very effective at that point, but conversely, the control is not effective at the frequency in between. In this case, it can be seen that the repetition control is effective at 16 Hz or less. Thus, as can be seen from FIG. 3, the repetition control works effectively in the low frequency band.

  The rotational speed detecting means 6 detects the rotational angular speed of the rotating body 1 and sends the detected rotational angular speed value to the transfer function calculating means 4 and the control means 3. Here, as shown in FIG. 2, the rotational speed detection means 6 is actually disposed on a shaft for transmitting the rotational torque of the gear train to the rotating body 1, and detects the rotational angular velocity of this shaft. .

  Here, the change in the rotational angular velocity does not affect the fixed portion such as the gear train, and is mostly caused by the change in the torque of the driving unit 2 and the contact coefficient between the rotating body 1 and the intermediate transfer belt. This change in torque occurs when a large amount of toner rides on the rotating body 1 and the rotating body becomes heavy. In addition, when the gear is changed, the rotational angular velocity changes.

  The transfer function calculating means 4 removes the rotational angular velocity given by the control command signal from the control means 3 from the rotational angular velocity value received from the rotational speed detecting means 6, and outputs the output value from the test signal generating means 5. The rotational angular velocity is obtained by analyzing each frequency. The removal of the rotational angular velocity means, for example, that a control command signal is sent to the driving means 2 without adding a test signal, the rotational angular velocity at that time is measured, and the rotational angular velocity based on the control command signal with the test signal added is measured. You may make it pull from. The transfer function calculating means 4 repeats the acquisition of the output value from the test signal generating means 5 and the transmission ratio of the rotating system 8 5000 times, and the acquired output values from the respective test signal generating means 5 and the rotation system 8 corresponding thereto. The transmission ratio is stored in a storage unit (not shown) included in the transfer function calculation unit 4. Next, taking the output value from the test signal generating means 5 on the horizontal axis and the transmission ratio of the rotating system 8 on the vertical axis, the stored 5000 points are plotted and a graph showing the transfer characteristics of the rotating system 8 is created. To do. Here, if the number of points to be plotted is large, the transfer characteristic graph becomes more accurate, but conversely, it takes time to create the graph in proportion to the amount of points to be plotted. Therefore, in the present embodiment, 5000 points are plotted as points necessary for creating a certain degree of accurate graph in a short time, but this may take other values depending on the relationship between time and accuracy. . In the present embodiment, the points on the graph of the output value and the transmission ratio are plotted and the function is obtained. However, the function calculation method is not particularly limited as long as the function representing the transfer characteristic can be obtained.

  Here, the transfer function calculating means 4 confirms the transfer ratio with respect to the output value from the test signal generating means 5 of 3 Hz, for example, and the value is a value twice as large as the transfer ratio in a state where no signal deterioration occurs. If it exceeds, the warning means 7 is notified of the warning. For example, if the transmission ratio with respect to 3 Hz when no deterioration occurs is 0.8, a warning is notified if the transmission ratio after the occurrence of deterioration exceeds 1.6. Here, in this embodiment, 3 Hz having a large influence on the rotational speed of the rotating body 1 is taken as a reference. However, the reference frequency may be any other frequency as long as it has a low frequency that has a large influence on the rotational speed. The output value from the frequency test signal generator 5 may be used as a reference. Further, in the present embodiment, if the measured transmission ratio reaches twice the transmission ratio in a state where no deterioration has occurred, it is difficult to control, so that the threshold is set in a state in which no deterioration has occurred. However, the threshold value is not particularly limited as long as the threshold value is determined to be uncontrollable. For example, the upper limit of the transmission ratio is 2 and the addition / subtraction is an absolute value such as 0.1. It is also possible to take other values.

  The transfer function calculation means 4 calculates a function identified in the created graph. In this calculation method, a constitutive model of the image output device is set, and dynamic characteristics including drum drive and belt movement are expressed by a motion equation, and the characteristics calculated from the motion equation are actually plotted on a graph. A function to be obtained is calculated by changing parameters such as a torque constant of the motor and a contact coefficient between the drum and the belt which greatly change depending on the apparatus state so as to match the arrangement of the points.

  The transfer function calculation unit 4 calculates an inverse function of the obtained function. This inverse function is obtained by creating an inverse function for the dynamic equation of motion and substituting the equation with a discrete equation that matches the control sampling.

  The transfer function calculation means 4 extracts parameter values for calibrating the inverse characteristic filter from the obtained function. Here, in the drive system of the present invention, what is considered to affect the fluctuation of the rotational angular velocity of the rotating body is the torque constant of the drive means, so the parameters are the torque constant in the function and the contact coefficient between the drum and the belt. Is the coefficient in the term. Further, the transfer function calculation unit 4 sends the parameter value to the control unit 3.

Here, the configuration of the inverse characteristic filter will be described using values. The rotational angular velocity of the target rotating body 1 is ω ₀ (001 in FIG. 1), the control command signal before calibration of the inverse characteristic filter for obtaining this angular velocity is X ₀ (002 in FIG. 1), When the transfer function of the rotating system 8 is F ₀ (X), it is originally ω ₀ = F ₀ (X ₀ ) (003 in FIG. 1). In other words, if the inverse function of Y = F ₀ (X) is X = F ₀ ⁻¹ (Y) (004 in FIG. 1), then X ₀ = F ₀ ⁻¹ (ω ₀ ). However, the transmission characteristics of the rotating system 8 change depending on the adhesion of toner and the contact coefficient between the photosensitive drum and the intermediate transfer belt. Therefore, the transfer function calculating means 4 calculates a transfer function that changes from the output value from the test signal generating means 5 and the rotational angular velocity detected by the rotational speed detecting means 6, and this transfer function is expressed as Y = F (X). To do. The Y = the angular velocity of the rotating body 1 also enter the F (X) in the control command signal X ₀ to a target can not be obtained. Therefore, the transfer function calculation means 4 calculates an inverse function X = F ⁻¹ (Y) (005 in FIG. 1) of the calculated transfer function. Parameters such as the torque constant of F ⁻¹ (Y) and the contact coefficient between the drum and the belt are sent to the repetitive control means 31, and the repetitive control means 31 converts the function of the inverse characteristic filter to F ⁻¹ (Y) (FIG. 1). To 006). Here, the control command signal F ⁻¹ (ω ₀ ) (007 in FIG. 1) is obtained in response to the target value ω ₀ of the rotational angular velocity of the rotating body 1. Since this control command signal F ⁻¹ (ω ₀ ) is ω ₀ = F (F ⁻¹ (ω ₀ )) (008 in FIG. 1), it passes through the current transfer function F (X) of the rotating system 8. This is a control command signal that becomes ω ₀ when As described above, the control command signal for obtaining the target value of the rotational angular velocity of the rotating body 1 after the change of the transfer characteristic is obtained, and the control command signal is sent to the driving means 2.

In other words, the transfer function calculation means 4 measures that the transfer function of the rotating system 8 has changed from F ₀ (X) to F (X), and repeat control is performed using the inverse function F ⁻¹ (Y). It can be said that the inverse characteristic filter of the means 31 is calibrated.

In the present embodiment, calibration of the inverse characteristic filter by changing the parameters described above is performed by performing a calibration operation when the operator decides once a day or once a month. The calibration for is configured to maintain the state until the next calibration operation is performed. For example, the image forming apparatus is provided with an original image forming mode and a calibration mode. In the calibration mode, the reverse characteristic filter of the repeat control unit 31 is changed from F ₀ ⁻¹ (Y) to F ⁻¹ (Y) as described above. After the calibration is completed, the mode is switched to the image forming mode, the connection for adding the test signal from the test signal generating means 5 to the control command signal, and the connection from the transfer function calculating means 4 to the repeat control means 31 Is cut and original image formation is performed. In this image forming mode, the transfer function calculating means 4 receives the output value from the test signal generating means 5 and the rotational angular velocity from the rotational speed detecting means 6 and warns the warning means 7 when the above threshold value is exceeded. You may make it the structure to notify. The timing for performing such a calibration mode is determined according to the degree of deterioration of the rotating system 8 with respect to time.

  When the inverse characteristic filter is calibrated when the image forming apparatus is actually performing image formation, the test signal level is lowered as much as possible so that the influence of the test signal on image formation is minimized. Need to be done.

  Next, the flow of calibration of the inverse characteristic filter by the transfer function calculating means 4 will be described with reference to FIG. Here, FIG. 4 is a flowchart of the calibration of the inverse characteristic filter by the transfer function calculation means 4.

  Step S001: The test signal generation means 5 sends the test signal to the transfer function calculation means 4 and places the test signal on the control command signal sent from the control means 3 to the drive means 2.

  Step S002: The rotational speed detecting means 6 detects the rotational angular speed of the rotating body 1 and sends it to the transfer function calculating means 4.

  Step S003: The transfer function calculating means 4 calculates a transfer ratio corresponding to the output value of the test signal generating means 5 based on the received rotational angular velocity, and stores it in the storage means.

  Step S004: The transfer function calculation means 4 determines whether the predetermined number of times (5000 times) has been completed. If not completed, steps S001 to S003 are repeated. If completed, the process proceeds to step S005.

  Step S005: The transfer function calculation means 4 plots the saved output values of the 5000 test signal generation means 5 and the transfer ratios corresponding to the output values of the test signal generation means 5, and creates a graph.

  Step S006: The transfer function calculating means 4 determines whether or not the transfer ratio at a predetermined frequency (3 Hz) exceeds a threshold value (1.6). If the threshold is not exceeded, the process proceeds to step S007, and if the threshold is exceeded, the process proceeds to step S011.

  Step S007: The transfer function calculation means 4 creates a function (Y = F (X)) representing transfer characteristics.

Step S008: The transfer function calculation means 4 creates an inverse function (X = F ⁻¹ (Y)) of the function Y = F (X).

Step S009: The transfer function calculation means 4 extracts the parameter value from the inverse function X = F ⁻¹ (Y), and sends the parameter value to the control means 3.

  Step S010: The control means 3 receives the parameter value from the transfer function calculation means 4, and calibrates the inverse characteristic filter of the repetition control means 31.

  Step S011: The transfer characteristic means 4 notifies the warning means 7 of the warning and ends the calibration of the inverse characteristic filter.

[Second Embodiment]
A second embodiment of the present invention will be described. In the second embodiment of the present invention, the inverse characteristic filter is calibrated using a test signal in a low frequency band instead of white noise including a low frequency band to a high frequency band as a test signal. .

  In this regard, if a lot of noise is added to the control command signal, there is a high risk of causing a positional deviation of the image to be formed. For this reason, the test signal is less affected by image formation when the frequency band is narrowed as much as possible. Further, the frequency band that most affects the rotational angular velocity of the rotating body 1 is a frequency band having a period close to the time taken for one rotation of the rotating body 1, and the rotating body 1 rotates 2-3 times per second, It is preferable to use a test signal with a low frequency band, in particular a test signal with a frequency band of 2 to 3 Hz. Thus, since only the signal in the frequency band that most affects the rotational angular velocity of the rotating body 1 has a large effect on the rotational angular velocity of the rotating body 1, and the signals in the other frequency bands are small enough to be ignored, Control of the control command signal is possible.

  Here, the operation of the image forming apparatus in the present embodiment will be described. In response to the signal obtained by adding the test signal in the low frequency band from the test signal generating means 5 to the control command signal output from the control means 3, the rotating body 1, the driving means 2 and the rotational speed detecting means 6 are in the first embodiment. The rotational angular velocity is sent to the transfer function calculation means 4 in the same manner as the configuration. Further, an output value from the test signal generating means 5 having a low frequency component is sent to the transfer function calculating means 4.

  The transfer function calculating means 4 receives the rotation angular velocity and the output value from the test signal generating means 5 and, like the first embodiment, the transfer function corresponding to the output value from the test signal generating means 5 having a low frequency component. Get the ratio. Similarly to the case of the first embodiment, the transfer function calculation means 4 stores the acquired output value from each test signal generation means 5 and the value of the transfer ratio for the output value inside the transfer function calculation means 4. A graph representing the transfer characteristics of the rotating system 8 by plotting the stored points with the horizontal axis representing the output value from the test signal generating means 5 and the vertical axis representing the transmission ratio. Then, a transfer function which is a function to be identified in the graph is obtained, an inverse function of the transfer function is calculated, a parameter value for calibrating the inverse characteristic filter is calculated, and the value of the parameter is controlled by the control means 3 Send to.

  As in the first embodiment, the control means 3 calibrates the inverse characteristic filter using the received parameter value, and calculates a control command signal corresponding to the target rotational speed of the rotating body 1. The control command signal is sent to the driving means 2.

  As described above, by controlling using a signal having a low frequency component that greatly affects the rotation speed of the rotating body 1 as a test signal, while reducing the load caused by the calculation of the transfer function calculating means 4 and the like, The rotating body 1 can be controlled with high accuracy.

1 is a block diagram of an image forming apparatus according to the present invention. 1 is a configuration diagram of a drive control device of an image forming apparatus according to the present invention. The figure showing the control characteristic of the image control apparatus which concerns on this invention The figure which shows the flow of the calibration of the inverse characteristic filter by a transfer function calculation means

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating body 2 Drive means 3 Control means 31 Repeat control means 32 PI control means 4 Transfer function calculation means 5 Test signal generation means 6 Rotational speed detection means 7 Warning means 8 Rotation system

Claims (5)

An image forming apparatus comprising: a rotating body for transferring an image; a driving unit that rotates the rotating body; and a control unit that provides a control signal to the driving unit to control the speed of the rotating body. ,
Test signal generating means for generating a test signal including a frequency band of 2 Hz to 16 Hz and adding the test signal to the control signal;
Angular velocity detecting means for detecting the rotational angular velocity of the rotating body;
A transfer function calculating means for obtaining a latest transfer function of a rotating system including the rotating body and the driving means based on the rotational angular speed and the test signal from the angular speed detecting means,
The control means controls the drive means so as to achieve the desired rotational angular velocity based on the inverse function of the transfer function of the rotating system corresponding to the desired rotational angular velocity and the inverse function of the latest transfer function. An image forming apparatus that controls the image forming apparatus. The control means has an inverse characteristic filter based on an inverse function of the transfer function in advance, and repeat control for outputting the control signal obtained by passing information on a specified desired rotation speed through the inverse characteristic filter With means,
The transfer function calculating unit, based on the latest transfer function to calculate the parameter values for changing the inverse characteristic filter in the reverse characteristic filter for the latest transfer function, transmitting said repeat control means The control signal obtained by passing the information on the desired rotational angular velocity through an inverse characteristic filter including the calculated parameter value is output to the repetition control means. The image forming apparatus described in 1.   3. The apparatus according to claim 1, further comprising PI control means for performing proportional control and integral control in response to information on the rotational angular velocity in addition to control of the drive means by a control signal of the repeat control means. The image forming apparatus described.   4. The image forming apparatus according to claim 1, further comprising warning means for notifying a warning when the value of the transfer function exceeds a predetermined value.   The image forming apparatus according to claim 1, wherein the rotating body is a photosensitive drum or an intermediate transfer belt.

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