JP2710839B2 - Image exposure drive motor control method and apparatus - Google Patents

Description

The present invention relates to a control method of an image exposure drive motor of an image forming apparatus for forming a latent image on a photoreceptor such as a copying machine and changing the visualization by a developing unit, and It concerns the device.

[Prior Art] Conventionally, speed control in this type of device is performed by using a well-known phase locked loop (PLL).
P). In this case, the control during the transitional time, such as when the motor starts, when switching to the rotation direction, or when the motor stops, and the control during the steady state after the target rotation speed is reached
The internal constant (gain) of L control is switched. By doing so, the supply current to the motor during the transition period is limited to suppress overshoot, and a smooth transition to the steady state is realized.

[Problems to be Solved by the Invention] However, since the supply current to the motor is limited during the transition period, the time required for the transition period increases, and at the time of startup, the approach distance from the start to the image front end is set to be long. However, there is a problem that the apparatus becomes large. Further, there is another problem that the transient required time affects the cycle from one image exposure to the next image exposure.

The present invention has been made in view of the above points, and an object of the present invention is to improve control of a transition period. Specifically, during a transitional period in which the relationship between the state quantity and the control quantity is ambiguous, the control quantity is calculated and controlled by performing a fuzzy inference on the ambiguous relation, and an image exposure drive motor control method and apparatus therefor. Is to provide.

Further, in the control of the transition period, the load fluctuation due to the aging of the device and the torque fluctuation due to the temperature rise of the motor are large.
If the rules used in the fuzzy inference are constant, there is a problem that the control state changes.

It is a further object of the present invention to provide an image exposure drive motor control method and apparatus for improving control of a transition time using fuzzy inference for the above-mentioned fluctuation.

[Means for Solving the Problems] In order to solve this problem, a control method of an image exposure drive motor according to the present invention employs an image exposure method in an image forming apparatus which forms a latent image on a photoreceptor and visualizes the latent image by a developing unit. A drive motor control method, comprising a plurality of fuzzy rules, wherein when the optical motor is in a transitional period, a predetermined rule in the plurality of fuzzy rails is selected corresponding to a required time of the transitional period, and From the ambiguous relationship between at least one state quantity and the speed control amount among the optical motor speed detected by the motor encoder, the target speed of the optical motor, and the position of the optical system, calculate the speed control amount by fuzzy inference, The optical motor is controlled based on the speed control amount.

Here, during the transition period, the rotation direction of the optical motor is reversed in order to reverse the moving direction of the optical system until the optical system reaches the vicinity of the front end of the image after the start of driving of the optical motor, and then the optical motor reaches the target speed. Or after the start of speed control for stopping the driving of the optical motor.

In a steady state other than the transition period, the optical motor speed is controlled by the PLL using the optical motor speed detected by the optical motor encoder and the target speed of the optical motor.

Further, the control device of the image exposure drive motor of the present invention is a control device of an image exposure drive motor in an image forming apparatus for forming a latent image on a photoreceptor and visualizing the latent image by a developing means, and detects the image by an encoder of an optical motor. First optical motor speed control means for controlling the optical motor speed by a PLL using the optical motor speed and the optical motor target speed, and the optical motor speed and the optical motor target detected by the optical motor encoder. State quantity detection means for detecting at least one state quantity among the speed and the position of the optical system, and function storage means for storing a function expressing the state quantity and the speed control quantity in at least one ambiguous set, A rule storage means for storing a function of the state quantity and the speed control quantity in association with a plurality of qualitative rules, and a plurality of rules stored in the rule storage means. Selecting means for selecting one rule based on the required time from the rules, and calculating the degree belonging to the set of speed control amounts from the degrees belonging to the set of state quantities according to each of the rules. Inference means for inferring the most likely speed control amount, second optical motor speed control means for controlling the optical motor speed based on the speed control amount inferred by the inference means, and And control switching means for switching between control by the first optical motor speed control means and control by the second optical motor speed control means.

Here, the selection means selects the plurality of rules in accordance with a time deviation from the start of driving of the optical motor to the time when the optical system reaches the vicinity of the front end of the image. Is reached, the control is switched from the control by the second optical motor speed control means to the control by the first optical motor speed control means.

Further, when the rotation direction of the optical motor is reversed in order to reverse the moving direction of the optical system, the switching unit controls from the control by the first optical motor speed control unit to the control by the second optical motor speed control unit. The selection means selects the plurality of rules in accordance with a time deviation from the reversal of the rotation direction of the optical motor to the speed of the optical motor reaching the target speed. Then, the control is switched from the control by the second optical motor speed control means to the control by the first optical motor speed control means.

Further, the switching means switches from the control by the first optical motor speed control means to the control by the second optical motor speed control means at the time of starting the speed control for stopping the driving of the optical motor, The plurality of rules are selected according to a time deviation until the drive of the optical motor is stopped.

Example An example of the present invention will be described below in detail with reference to the drawings.

<Example of Configuration> FIG. 2 is a simplified cross-sectional view of the copying apparatus of the present embodiment. 110 is a platen glass on which a document to be copied is placed, 12 is an optical system having an illumination lamp for illuminating the document, 108 is a home sensor for detecting that the optical system is at a reference position, 109
Reference numeral denotes an image sensor for detecting that the optical system advances and is at the leading end of the document. Further, a detection signal from the image sensor is generated even when the optical system moves backward. 111 is a photosensitive drum.

FIG. 1 is a basic block diagram of the optical motor control unit of the copying apparatus according to the present embodiment. Reference numeral 106 denotes a motor for driving the optical system 112. The motor drives forward rotation (optical system forward) and reverse rotation (optical system backward). 105 is a driver for the motor 106. An encoder 107 is connected to the motor 106, and outputs a signal synchronized with the rotation of the motor 106. Reference numeral 100 denotes a well-known PLL control unit.When the motor 106 is rotated at a desired speed, a reference frequency FS corresponding to the desired speed is input so that the phase angle with the encoder signal FG from the motor 106 is changed. A pulse width modulation signal P1 serving as a speed control signal for the motor 106 is output so as to have a constant angle.

Reference numeral 101 denotes a motor speed control by fuzzy inference described later, an output of a reference frequency FS necessary for performing the motor speed control by the PLL, a forward / reverse control signal F / R, and a drive stop control signal O.
This is an arithmetic and control CPU that controls forward / reverse / stop by N / OFF and switching control between motor speed control by PLL control and fuzzy control. The counter d _C , counter t _C , timer T _S, and a timer T _E. 103 is CPU
A ROM for storing a program to be controlled by 101, a fuzzy rule 103a and a membership function 103b to be described later. Here, the fuzzy rule 103a has a plurality of fuzzy rules such as a fuzzy rule 1, a fuzzy rule 2,.
Is used as a work area when performing control and fuzzy inference
It is a RAM, and has a last required time 102a for storing the last required time of the fuzzy control. A switching switch 104 switches between the speed control signal P1 output by the PLL and the speed control signal P2 output by the fuzzy inference (here, P1 and P2 are both pulse width modulation signals).
Switchable with SW. 108 is the home sensor described above, and 109 is the image sensor. Its output signal (High / Lo
w) are both input to the CPU 101.

<Operation Example> Next, an operation example of speed control by fuzzy inference of the optical motor of the present embodiment will be described. The description of this operation example is the first.
This is performed using FIGS.

The CPU 101 counts the number of pulses output from the encoder 107 of the optical motor for a certain period of time, thereby
The speed of 112 is calculated, and the difference between the calculated speed and the target speed is calculated as a speed deviation. The distance deviation between the optical system 112 and the target position is calculated by comparing the number of pulses required for movement between the reference position and the target position with the number of pulses input from the encoder after passing through the reference position.

 In order to perform the fuzzy inference this time, two state quantities, the speed deviation of the target speed from the current speed and the distance deviation of the target position from the current position, are used.

 Also, as a control amount for controlling the speed of the optical system, an optical motor speed control amount is used.

3A to 3C show a fuzzy set called a membership function of the above-mentioned state quantities and control quantities.

The speed deviation, the distance deviation, and the optical motor control amount are largely divided into several groups. For example, in the case of a speed deviation, 1) S _s ...

2) M _s … Medium speed deviation.

3) L _s : Speed deviation is large.

In the case of a distance deviation, 1) S _d ... the distance deviation is small.

2) M _d ... Distance deviation is medium.

3) a large L _d ... distance deviation.

And The degree belonging to each set is represented by a value from 0 to 1. Fig. 3A shows the membership function of the speed deviation, Fig. 3B
The figure shows the membership function of the distance deviation, and FIG. 3C shows the membership function of the optical motor control amount.

Next, a method of calculating the control amount of the optical motor from the state amount between the speed deviation and the distance deviation will be described. For determining the optical motor control amount, for example, the following fuzzy rule is used.

(Rule 1) If, if the speed deviation = L _s and distance deviation = M _d, the optical motor control amount = M _c (Rule 2) If velocity deviation = M _s and distance deviation = if M _d, the optical motor control Amount = S _c Thus, the fuzzy rules are set as required. No.
4A and 4B show the fuzzy rule used in the present embodiment. Here, each fuzzy rule has two rules, a “normal rule” and a “rule after correction”.

FIG. 5 is an example of calculating the control amount of the optical motor by performing fuzzy inference using the above (rule 1) and (rule 2). For example, speed deviation = x, distance deviation =
Consider the case of y.

In (Rule 1), the degree of μx to the input x by Menbashitsupu function of the speed deviation in the set of L _s at μy degree of relative input y by Menbashitsupu function of distance deviation in the set of M _d It is. Thereafter, the minimum value of μx and μy is taken, and the value is defined as the degree to which the condition part of (rule 1) is satisfied. The value and the MIN (minimum value) between Menbashitsupu function M _c of the control amount of the optical motor Taking operation becomes trapezoid indicated by the shaded area in S. The same calculation is performed in (rule 2), and the shape shown by the shaded portion of T comes out.

Thereafter, the sum of the set of S and the set of T is calculated, and a new set of U indicated by the hatched portion is created. In this case, the control amount of the optical motor obtained by fuzzy inference is set for the center of gravity P. In the case of the speed deviation = L _s and distance deviation S _d, in the case of the speed deviation = M _s and distance deviation S _d is not shown.

As described above, for all the fuzzy rules shown in FIG. 4, the degree of belonging to the fuzzy set of the control quantity is calculated from the degree to which the state quantity belongs to the fuzzy set in accordance with each of the fuzzy rules by the method described above, and the degree of belonging to each rule is calculated. The sum of the sets is calculated, the most likely control amount is calculated by obtaining the center of gravity, and the center of gravity is set as the control amount of the optical motor. Then, the optical motor is controlled according to the set optical motor control amount. This control amount is the PW of the optical motor.
M output DUTY.

<At the time of starting the optical system> Next, the procedure of fuzzy inference at the time of starting the optical system driving motor will be described with reference to the flowcharts of FIGS.

The routine of FIG. 6 is executed each time the optical system moves a predetermined distance (d) due to an encoder interrupt. This encoder interrupt routine is used until the position of the optical system reaches the image destination. On the other hand, apart from this routine, an interrupt routine for time measurement is provided in step S20 in FIG.
Counts up-counter t _C in a predetermined time interval. Counter t _C is cleared to zero at step S13 in during routine Figure 6. Accordance connexion, the moving speed of the optical system at that time from the value of the counter d _C and t _C is obtained.

First counts up-optical system moving distance counter d _C at step S11. Step obtains a moving speed-S12 the value of the counter t _C In, calculates the speed deviation. Counter t
_C is cleared to zero in step S13 after the processing in step S12 ends. Calculating the distance deviation from the value of the counter d _C at step S14.

Next, in step S21, based on the time required for starting the previous optical system drive motor (the time from the start of the motor to the end of the control by the fuzzy inference), if the time required for the previous start is less than 200 msec, The control is performed by using the “normal rule” in FIG. 4A, and by using the “corrected rule” in FIG. 4A for 200 msec or more.

Next, in steps S15 and S16, the degree to which the state quantity belongs to the fuzzy set for each of the moving distance and the moving speed is determined, and the degree to which the control quantity belongs to the fuzzy set based on the newly set fuzzy rule is determined from the values. Ask. When this operation is completed for all the rules to be considered, the process proceeds from step S15 to step S17, where the sum of the sets belonging to each rule is calculated, and the most probable control amount is calculated by calculating the center of gravity in step S18. Then, in step S19, the center of gravity is set as PWM data for controlling the optical system drive motor.

When the moving speed of the optical system is set, the speed control of the optical system driving motor is switched to the PLL. At the same time, the time required from the start of the optical system drive motor to that time is stored. This value is referred to at the next correction of the fuzzy rule.

<At the time of reversing the optical system> Next, the procedure of fuzzy inference when the rotation direction of the optical system driving motor is reversed will be described with reference to the flowcharts of FIGS.

The routine of FIG. 6 is executed each time the optical system moves a predetermined distance (d) due to an encoder interrupt. This encoder interrupt routine is used until the speed reaches a certain set value after reversing the moving direction of the optical system. On the other hand, the present routine is provided separately from the seventh view of a time measurement interrupt routine, and counts up-counter t _C in a predetermined time interval. Subsequent processing in each step is the same as that at the time of startup. At the time of reversing, for example, the last required reversing time is less than 300 msec based on the required reversing time (from the motor reversing to the time when the moving speed of the optical system reaches a predetermined value) at the time of reversing the optical system driving motor. Time is the "normal rule" in Figure 4A
In the case of 300 msec or more, control is performed by using the “rule after correction” in FIG. 4A.

When the moving speed of the optical system reaches the set value, the speed control of the optical system driving motor is switched to the PLL. At the same time, the time required from the inversion of the optical system drive motor to that time is stored.
This value is referred to when correcting the fuzzy rule described above.

<When the optical system is stopped> Next, with reference to the flowcharts of FIGS. 6 and 7, the procedure of the fuzzy inference when the optical system drive motor is stopped will be described.

The routine of FIG. 6 is executed each time the optical system moves a predetermined distance (d) due to an encoder interrupt. This encoder interrupt routine is used from the time the optical system movement stop command is received until the moving speed of the optical system reaches zero. Until a command to stop the movement of the optical system is received, the movement of the optical system is controlled by a conventional method. On the other hand, the present routine is provided separately from the seventh view of a time measurement interrupt routine, and counts up-counter t _C in a predetermined time interval. Hereinafter, the processing of each step is the same as that at the time of starting and reversing. Here, at the time of a stop, for example, the last required brake time is based on the required brake time (time until the moving speed of the optical system reaches zero after receiving the motor stop command) when the previous optical system drive motor was stopped. When the time is shorter than 150 msec, the control is performed by using the “normal rule” in FIG. 4B, and when the time is 150 msec or longer, the control is performed by using the “corrected rule” in FIG. 4B.

When the moving speed of the optical system reaches zero, the time required from receipt of the motor stop command to that time is stored. This value is referred to the correction of the fuzzy rule described above. After the stop, normal start-up or inversion is performed.

<Switching Between Fuzzy Control and PLL Control> Next, referring to the flowchart of FIG. 8, the optical system drive by the fuzzy speed control and the PLL speed control when the optical system drive motor is started, inverted, and stopped. Switching of the motor speed control will be described.

First, in step S31, a target frequency FS (1 KHz) corresponding to the target speed of the optical system drive motor is output to the PLL. In step S32, the speed control of the optical system drive motor is switched to the fuzzy speed control, and at the same time, the timer is set in step S32a.
Cleared to zero T _E. In step S33, the optical system drive motor is rotated forward (forward). In step S34, it is determined whether or not the optical system has arrived at the image destination. If not, the process waits for arrival at the image destination while performing fuzzy control in step S34 for each predetermined distance.

In step S35 the speed control of the optical system driving motor with switched to PLL velocity control is stored as the last required time at the time of driving the value of the timer T _E at step S35a. Step S3
In step 6, a timer T _S is set for reversing the optical system drive motor. In the step S37, the timer T _S is to determine whether or not Taimuatsupu, if you have not Taimuatsupu wait for Taimuatsupu at step S37. Step S
At 38, the target frequency FS (3 KHz) corresponding to the target speed when the optical system drive motor is reversed is output to the PLL.

Step S39 the speed control of the optical system driving motor with switched to fuzzy velocity control, reset to zero the timer T _E at step S 39 a. In step S40, the optical system drive motor is reversed (reverse). In step S41, it is determined whether or not the frequency output by the optical system drive motor via the encoder is equal to the target frequency FS output in step S38. If they are equal, the process proceeds to step S42. If they are not equal, the process waits for the target frequency to be reached while performing fuzzy control for each predetermined distance.

In step S42, the speed control of the optical system drive motor is
With switching to speed control, the timer T _E at step S42a
Is stored as the last required time at the time of inversion. Step
In S43, it is determined whether the optical system has reached the image destination. If so, go to step S44; if not, go to step S44.
Wait to arrive at 43.

In step S44, switches the speed control of the optical system driving motor to fuzzy velocity control, reset to zero the timer T _E at step S44a. Step speed control is a step
This is performed until the optical system stops in S45. When the optical system is stopped, it stores the value of the timer T _E as the last required time at stop in step S46.

[Effects of the Invention] As described above, according to the present invention, at the time of transient control such as when the image exposure drive motor is started, when the rotation direction is switched, and when the image exposure drive motor is stopped, the speed control is switched to the speed control based on the fuzzy inference. The time required for a typical part can be reduced, and the influence on the cycle from one image exposure to the next image exposure can be reduced.
In addition, the approach distance can be set short. Therefore, the size of the apparatus can be reduced. Further, since the time is shortened and the smooth transition to the steady state is realized, there is an effect that the device can be made compact and the image quality can be stabilized.

Further, by measuring the required time during transitional control times such as when the image exposure drive motor is started, when the rotation direction is switched, when the image exposure drive motor is stopped, and by switching a plurality of rules used for fuzzy inference according to the measured data, Stable control is possible even for load fluctuation due to aging and torque fluctuation due to motor temperature rise.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic block diagram of an optical motor control unit of a copying apparatus according to the present embodiment, FIG. 2 is a simplified sectional view of the copying apparatus according to the present embodiment, and FIG. FIG. 3B is a diagram showing an example of a membership function of a distance deviation, FIG. 3C is a diagram showing an example of a membership function of an optical motor control amount, and FIG. 4A and FIG. FIG. 5 is a diagram showing a fuzzy rule of the embodiment, FIG. 5 is a diagram showing an example of fuzzy inference of the present embodiment, FIG. 6 is a flowchart showing a procedure of an encoder interrupt routine, and FIG. 7 is a flowchart showing a procedure of a timer interrupt routine. FIG. 8 is a flowchart showing a switching procedure between the fuzzy speed control and the PLL speed control. In the figure, 100: PLL control unit, 101: CPU, 102: RAM, 10
2a: Previous time required, 103: ROM, 103a: Fuzzy rule, 103b: Membership function, 104: Switching switch, 105: Driver, 106: Motor, 107: Encoder, 108: Home sensor , 109 …… Image sensor, 110
... Original platen glass, 111... Photosensitive drum, 112... Optical system.

Claims (8)

(57) [Claims] 1. A control system for an image exposure drive motor in an image forming apparatus for forming a latent image on a photoreceptor and visualizing the latent image by a developing means, wherein a plurality of fuzzy rules are provided and the optical motor is in a transition period. A predetermined rule among the plurality of fuzzy rules is selected in accordance with the required time of the transition period, and among the optical motor speed detected by the encoder of the optical motor, the target speed of the optical motor, and the position of the optical system, From the ambiguous relationship between at least one state quantity and the speed control quantity,
A control method of an image exposure drive motor, wherein a speed control amount is calculated by fuzzy inference, and an optical motor is controlled based on the speed control amount. 2. The method according to claim 1, wherein, after the start of the driving of the optical motor, the rotation direction of the optical motor is reversed to reverse the moving direction of the optical system until the optical system reaches the vicinity of the front end of the image. 2. The control system for an image exposure drive motor according to claim 1, wherein the control is performed until the target speed is reached or after the start of speed control for stopping the drive of the optical motor. 3. The optical motor speed is controlled by a PLL using an optical motor speed detected by an encoder of the optical motor and a target speed of the optical motor during a steady state other than the transient period. 2. A control method for an image exposure drive motor according to claim 1. 4. A control device for an image exposure drive motor in an image forming apparatus for forming a latent image on a photoreceptor and visualizing the latent image by a developing means, comprising: an optical motor speed detected by an encoder of the optical motor; A first optical motor speed control means for controlling an optical motor speed by a PLL using the target speed; and an optical motor speed detected by an optical motor encoder, a target speed of the optical motor, and a position of the optical system. State quantity detection means for detecting at least one state quantity; function storage means for storing a function expressing the state quantity and the speed control quantity by at least one vague set; and a function of the state quantity and the speed control quantity From a plurality of rules stored in the rule storage means based on a required time based on a required time. Selecting means for selecting three rules, calculating a degree belonging to the set of speed control quantities from degrees belonging to the set of state quantities according to each of the rules, and inferring the most likely speed control quantity from among them. Second optical motor speed control means for controlling the speed of the optical motor based on the speed control amount inferred by the inference means; and at a predetermined timing, the first optical motor speed control means And a control switching means for switching between control by the second optical motor speed control means and control by the second optical motor speed control means. 5. The image processing apparatus according to claim 1, wherein the selection unit selects the plurality of rules in accordance with a time deviation from when the optical motor is driven to when the optical system reaches the vicinity of the front end of the image. 5. The control of the image exposure drive motor according to claim 4, wherein the control is switched from the control by the second optical motor speed control means to the control by the first optical motor speed control means when reaching the vicinity of. apparatus. 6. The control means according to claim 1, wherein said switching means reverses the rotation direction of said optical motor in order to reverse the moving direction of said optical system. 5. The control device for an image exposure drive motor according to claim 4, wherein control is switched to control by means. 7. The selection means selects the plurality of rules in accordance with a time deviation from the reversal of the rotation direction of the optical motor to the speed of the optical motor reaching the target speed. When it reaches
7. The control apparatus according to claim 6, wherein the control is switched from the control by the second optical motor speed control means to the control by the first optical motor speed control means. 8. The switching means switches from control by the first optical motor speed control means to control by the second optical motor speed control means when the speed control for stopping the driving of the optical motor is started. 5. The control device according to claim 4, wherein the means selects the plurality of rules according to a time deviation until the drive of the optical motor is stopped.