JP3306082B2 - Control method of scanner optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a scanner optical system used in, for example, a copying machine.

[0002]

2. Description of the Related Art FIG. 13 schematically shows an optical system configuration of a conventional copying machine of this type. First, a scanner optical system 2 is provided below a contact glass 1 on which a document (not shown) is set. As a result, an image formed by the reflected light from the document is formed on the drum-shaped photoconductor 3 via the scanner optical system 2. The scanner optical system 2 includes a first scanner 7 including an illumination light source 4, a reflector 5, a first mirror 6, and the like, a second scanner 10 including second and third mirrors 8, 9 and the like, an imaging lens 11, It comprises four mirrors 12 and the like. 13 is a dust-proof glass. Here, the first scanner 7 and the second scanner 10 have a 2: 1 speed ratio under a driving system configuration as shown in FIG. 14 so that the optical path length reflected from the document does not change during scanning. The motor is driven backward by the DC motor 14 and the scanner wire 15 (the configuration of the drive system itself in FIG. 14 is well known, and detailed description is omitted). A scanner home position sensor (hereinafter, referred to as an HP sensor) 16 having a reflective photointerrupter structure, which is located at a reference position of the scanner optical system 2 and serves as a detecting means, is provided at a predetermined position of the apparatus main body.
A part of the first scanner 7 is capable of shielding the sensor unit of the HP sensor 16 when the home position is reached.
A P shield plate 17 is provided.

Under such a configuration, FIG.
The scanner optical system 2 is driven to scan rightward from the HP state as shown by the solid line to expose and scan the original surface. The positions of the first and second scanners 7, 10 indicated by virtual lines in FIG. 13 indicate the maximum movement positions of the reciprocating operation. The scanner optical system 2 that has completed the exposure scanning moves backward toward the home position again. Here, when the scanner optical system 2 moves backward, it is generally driven at a higher speed than during forward movement, and deceleration control is performed when approaching the home position HP. And
When the HP shield plate 17 crosses the HP sensor 16, the rotation direction of the motor 14 is switched from reverse rotation (scanner backward movement direction) to normal rotation (scanner backward movement direction) to return from the overrun position to the home position HP. Things.

The acceleration control of the forward movement of the scanner optical system 2 will be described in detail. First, the operation of the scanner optical system 2 for one cycle is as shown in FIG. In FIG. 15, the horizontal axis represents the time axis, and the vertical axis represents the rotation speed of the DC motor 14 (or the speed of the first scanner 7).
The actual rotation speed (or the scanner speed) of the DC motor 14 becomes a solid line with respect to the target value indicated by the broken line.

Here, the acceleration control operation during forward movement will be described with reference to FIG. In the figure, the broken line parallel to the X axis is the target speed. The operation characteristic A indicated by a dashed line indicates that when the acceleration is controlled with a constant feedback gain due to a light sliding load of the scanner, the overshoot of the acceleration amount is too large and the speed is excessive near the leading edge of the document. .
The operating characteristic B indicated by a solid line indicates a case where the scanner sliding load is heavy, and when acceleration control is performed with a constant feedback gain, the load becomes a brake and the target speed does not reach the target speed at the leading end position of the document. Here, the operation characteristic C indicated by a broken line indicates an optimum acceleration state.

Next, a description will be given of a second conventional scanner control method for a copying machine. 13 and 14 are the same as those in the above-described conventional example, and the description thereof will be omitted. FIG. 17 shows the operation of the scanner optical system 2 for one cycle. FIG. 17 shows the operation by taking the time axis on the horizontal axis and the rotation speed of the DC motor 14 (or the speed of the first scanner 7) on the vertical axis, with respect to the target value indicated by the broken line. The actual rotation speed (or scanner speed) is shown by the solid line. FIG. 17 shows a method of gradually increasing the target speed at the time of acceleration with time. However, by making the target speed variable, calculation is required, or a data table showing an acceleration profile is required. Become. For this reason, the calculation takes a long time, the original control cannot be completed in time, and the control becomes impossible, or a data table that calculates the target speed during acceleration for each magnification change is required, resulting in a large program capacity. To increase. In order to avoid such a problem, usually, the target speed at the time of acceleration is often set to the target speed at the time of constant speed.
Also, when performing PID control, the gain of the control formula is one for each target speed because the target speed is constant from acceleration to a constant speed range. For this reason,
As shown in FIG. 18, if the gain is optimal to reduce the speed fluctuation in the region of constant speed, the speed overshoot becomes too large at the time of starting the scanner, and the speed cannot be maintained at the leading edge of the document, and the speed fluctuation is not maintained. The speed was insufficient at the leading edge of the document due to squeezing or insufficient acceleration.

Next, a third conventional method of controlling a scanner of a copying machine will be described. 13 to 15 are the same as the above-described first conventional scanner control method of the copying machine, and thus the description thereof is omitted. The acceleration during the forward movement and the constant speed operation will be described with reference to FIG. In the figure, the broken line is the target speed. The operation characteristic A shown in FIG. 19A shows that when the sliding load of the scanner is light and constant speed control is performed with a constant feedback gain, the gain is too large for the control target and the speed vibration of the scanner diverges. Show the situation. FIG.
The operating characteristic B shown in (b) shows that when the scanner sliding load is heavy and acceleration control is performed with a constant feedback gain,
The overshoot during acceleration is the operating characteristic C in FIG.
This indicates a state in which attenuation cannot be easily performed, that is, a case where the gain is too small for the control target.

[0008]

However, in the state of the first and second prior arts, if the document passes through the leading edge of the original document while accelerating, the copied image may be stretched or the speed may be too high. When a shot is taken, the tip image is in a state of vibrating, and in any case, a defect occurs in the copy image. Further, when the original is scanned in the state as in the third conventional example, the image is in a state of being vibrated, or a part of the image is stretched or shrunk. Occurs.

Therefore, the present invention has the following object. (1) In the forward movement of the scanner optical system, the gain is variable even if the rising profile up to a certain speed is different due to the difference in the forward movement start position or the variation in the mechanical load of each copying apparatus, thereby making the scanner optical variable. Provided is a control method of a scanner optical system of a copying machine, which can smoothly control a system to perform a stable copying operation. (2) In the forward movement of the scanner optical system, the operation of the scanner during the acceleration period and the operation of the scanner at the constant speed are smoothly connected, and the gain at the time of acceleration and the gain at the constant speed can be individually set. Optimal gain can be set for each scanner status, increasing speed stability at a constant speed and eliminating acceleration overshoot due to under-acceleration or over-acceleration during acceleration. To provide a control method of a scanner optical system of a copying machine, which can perform a stable copying operation by performing the above operations smoothly. (3) In the forward movement of the scanner optical system, even if the speed stability differs at a constant speed due to the variation of the mechanical load of each copying apparatus, the gain can be varied to smoothly control the scanner optical system at a constant speed. To provide a control method of a scanner optical system of a copying machine which can perform a stable copying operation.

[0010]

Means for Solving the Problems To solve the above problems, the present invention has the following configuration. (1) A scanner optical system capable of reciprocating operation, a scanner transport motor for transporting the scanner optical system, a moving speed detecting means for detecting a moving speed of the scanner optical system, and a scanner optical system. A moving distance detecting means for detecting a moving distance, and when the scanner optical system moves forward, the moving speed detecting means and the distance detecting means so as to stabilize at a predetermined scanning speed by a predetermined position. In a series of scanner optical system forward movement controls in which the obtained result is subjected to acceleration control for performing feedback control on the power applied to the motor, and is controlled to move at a constant speed when the reference position is reached, the movement is detected by the movement distance detecting means. The maximum scanner speed of the scanner up to the point where the leading edge of the document or a certain point before the leading edge of the document passes is read. Depending on the turbocharger down speed is obtained by the structure of the next subjected to feedback control as the acceleration control value at the time of forward scanning, that the gain of the feedback control system during acceleration is made variable. (2) a scanner optical system capable of reciprocating operation, a scanner carrying motor for carrying the scanner optical system, a moving speed detecting means for detecting a moving speed of the scanner optical system, and a scanner optical system. A moving distance detecting means for detecting a moving distance, and when the scanner optical system moves forward, the moving speed detecting means and the distance detecting means so as to stabilize at a predetermined scanning speed by a predetermined position. A series of scanner optical system forward control in which the obtained result is feedback-controlled to the power applied to the motor, and is controlled to move at a constant speed when the reference position is reached. In the control method using the integral term (I), the P value from an arbitrary position between the stop position of the scanner and the leading end position of the original is set.
At least one type of gain value of ID is different from the same type of gain value used for control after the position, and the value of the integral term up to that point is cleared at the position. It is what it was. (3) a scanner optical system capable of reciprocating operation, a scanner transport motor for transporting the scanner optical system, a moving speed detecting means for detecting a moving speed of the scanner optical system, and a scanner optical system. A moving distance detecting means for detecting a moving distance, and when the scanner optical system moves forward, the moving speed detecting means and the distance detecting means so as to stabilize at a predetermined scanning speed by a predetermined position. In a series of scanner optical system forward movement control in which the obtained result is subjected to acceleration control for feedback control to the power applied to the motor, and is controlled to move at a constant speed when the reference position is reached, the movement is detected by the movement distance detecting means. When the scanner speed and target speed exceed or fall below a certain value from the original position to the maximum scan position. The position information or the time is read, and according to the position information or the time information, feedback control is performed as a control value at a constant speed in the next forward scan, and the gain of the feedback control system at a constant speed is variable. It is a composition of what was done.

[0011]

[Action]

(1) According to the above means (1), when performing acceleration control of the forward movement operation of the scanner optical system, even if the acceleration profile fluctuates due to the fluctuation of the sliding load, the scanner optical system maintains the constant speed. Acceleration control can be performed smoothly, and a good copy result without extension of the leading edge image of the copied image can be obtained irrespective of fluctuations in the sliding load of the scanner optical system. (2) According to the above means (2), when performing acceleration control of the forward movement of the scanner optical system, the acceleration time can be shortened, and the copy speed can be improved. In addition, stable control of acceleration and constant speed becomes possible, and when moving from acceleration to constant speed, the speed curve becomes smooth, and the vibration of the scanner optical system and, consequently, the vibration of the image can be eliminated. (3) According to (3) of the above-described means, when performing acceleration control of the forward movement of the scanner optical system, even if the speed within a certain speed range fluctuates due to the fluctuation of the sliding load, the speed becomes higher at the next scan. Since the gain is repeatedly corrected to approach the constant speed, the speed of the scanner optical system becomes a constant speed, and therefore, there is no stretching, vibration, etc. of the copied image regardless of the fluctuation of the sliding load of the scanner optical system. Good copy results are obtained.

[0012]

1 to 7 show a first embodiment of the present invention.
It will be described based on. First, FIG. 1 shows a configuration of a control circuit of the scanner optical system 2. A microcomputer 20 serving as control means is provided. The microcomputer 20 is based on, for example, a μPD7811G, and the microcomputer 20 is connected to a programmable interval timer 21 using, for example, a μPD8253C as a measuring unit. The transfer DC motor 14 of the scanner optical system 2 is connected to the microcomputer 20 via drive transistors Tr1 to Tr4 and is drive-controlled. That is, the transistors Tr1 and Tr3 are turned on and the transistors Tr2 and Tr4 are turned on.
Is turned off, and the DC motor 14 is turned clockwise (CW).
The rotating current is supplied to the transistors Tr2 and Tr2.
When the transistor 4 is turned on and the transistors Tr1 and Tr3 are turned off, the DC motor 14 is supplied with a current rotating in the counterclockwise direction (CCW). Here, when the DC motor 14 rotates clockwise CW, the scanner optical system 2 moves forward, and when the DC motor 14 rotates counterclockwise CCW, the scanner optical system 2 moves backward.

The DC motor 14 is directly connected to a rotary encoder 22 as a pulse generating means. Here, the encoder 22 generates two pulse signals having different phases according to the rotation amount and the rotation direction of the DC motor 14. One is an A-phase encoder pulse ENCA, and the other is a B-phase encoder pulse ENCB. The A-phase encoder pulse ENCA is input to the counter input terminal CI of the microcomputer 20 via the buffer 23. As a result, the microcomputer 20 sets the pulse interval of the A-phase encoder pulse ENCA to the counter φ12 (transmission frequency of the oscillator 24 of the microcomputer 20 × 1/1).
Measure according to 12). The input signal to the counter input terminal CI is an interrupt input, and the measured data of the encoder interval (TIMER / EVENT COUNTER C) is processed during the processing of an interrupt program described later.
The value of the APURE REGISTER (ECPT) is read, and based on this data, the rotation speed (scanner speed) of the DC motor 14 is calculated, the error from the target rotation speed (target speed) is calculated, and the motor control is performed by the proportional / integral control calculation. The amount (ON time of the pulse width modulation PWM control) is calculated and output (data loading to the programmable interval timer 21).

Further, encoder pulses ENCA, ENC
B is input to the input terminal PC7 of the microcomputer 20 via the buffers 23 and 25 and the flip-flop 26, and is used for phase difference detection, and the rotation direction of the DC motor 14 is determined. An oscillator 27 is connected to the timer 21 to obtain a clock signal.

The control of the DC motor 14 is performed by PWM.
The control is performed. That is, the data of the PWM cycle is loaded into the counter 0 of the timer 21, and the output O of the counter 0 is output.
A square wave having a PWM cycle is output from UT0. This signal is the gate input of counter 1. This counter 1 is loaded with the ON time data of the PWM signal,
A one-shot output synchronized with the M cycle is output from OUT1, and the transistor Tr is output through the gate circuits 28 and 29.
3 or Tr4 is ON / OFF controlled. FIG. 2 shows a waveform example of such PWM control. In FIG. 2, even if the ON time tON is variable, the PWM cycle t (= tO
N + tOFF) is constant.

Here, counter 0 is set to mode 3 (square wave rate generator), and counter 1 is set to mode 1 (programmable one-shot). P
Since the WM cycle t is constant, the loading of the count value of the counter = 0 may be performed only once. And the PWM tO
Every time the N time is changed, the count number of the counter 0 is loaded.

Next, the contents of modes 3 and 1 of the programmable interval timer 21 will be described. FIG. 3 shows a timing chart of mode 3 (square wave rate generator). In this case, it operates as an n-divided counter of the input clock. The duty ratio when the count number is even is 1/2, and when the count number is odd, the duty ratio is (n-1) / 2n. For example, when the counter number n = 5, the duty ratio is 2/5 (active low). When this mode is selected by the control word, OUT0 = 1 and G
The count is loaded with ATE1 = 1. Thus, counting is started. When the count number is even, the first half of the count is OUT0 = 1 and the second half is O.
UT0 = 0. When the count number is odd, the first half (n + 1) / 2 of the count is OUT0 = 1 and the second half (n-1).
/ 2 becomes OUT0 = 0. If GATE1 = 0,
In synchronization with the fall, OUT0 = 1, and the counting stops. Thereafter, when GATE1 = 1, counting is restarted from the initial value. Then, when the count is loaded during the counting, a new counting is started from the next cycle. When the count number is even, the counter is decremented by 2; when it is odd, the counter is decremented by 1 at the first clock when OUT0 = 1, and decremented by 2 from the second clock.

FIG. 4 shows a timing chart of mode 1 (programmable one-shot). This is to output a one-shot pulse (active low) of a designated length. When this mode 1 is selected by the control word, OUT0 = 1, and after the count number is loaded, the count is started by being triggered by the rise of GATE1. OUT0 = 0 during the count, and OUT0 = 1 again when the count is completed. That is, the pulse width becomes a one-shot output of active low corresponding to the count number. When a trigger is applied during counting (when GATE1 is changed from 0 to 1), counting starts again from the initial value. Note that loading the count during counting does not affect the running count,
When a trigger is activated, counting starts at a new count.

Here, feedback control of the scanner speed will be described. The PWM value given to the scanner motor for each sampling of the input of the encoder, that is, the operation amount Y
n is represented by the following PID control equation. Yn = Kp × en + (1 / Ki) × Σen where en is the deviation of the current speed from the target value. Kp is generally called a proportional gain, and Ki is called an integral gain. In this embodiment, the speed information at the time of acceleration due to the fluctuation of the sliding load of the scanner optical system is reflected on the gain of feedback control at the time of the scanner going forward.

In this embodiment, the position information is obtained as follows. The pulse output from the encoder is counted by a microcomputer, and the pulse is counted up when the scanner goes forward, and is counted down when returning, so that the current position of the scanner can be accurately grasped. In order to detect the correct position of the scanner when the power is turned on, the scanner is slowly moved, and the location detected by the HP sensor 16 is set as a reference address (position) for all operations.

Next, a control method for raising the scanners based on the address information (scanner position information) will be described. Here, the address of the home position is set to 400 pulses, and the scanner moves during the forward movement, and the address is added each time one pulse is output from the encoder. At the time of return, the address is subtracted each time one pulse is output from the encoder. The forward movement and the backward movement can be determined by the scanner motor rotation direction detecting means. The leading edge address of the document is 450 pulses. That is, when the scanner is stopped by the HP sensor, the scanner must be started at a constant speed within a distance of 50 pulses. Usually this 5
The distance for 0 pulses is called the approach distance. In normal control, the gain of the feedback control (for example, PID control) and the initial power to be applied when starting the movement from the stop are determined in advance as fixed values so that the speed becomes constant within the approach distance.

On the other hand, the sliding load of the scanner changes due to various factors. Differences in the friction coefficient of each machine when assembling the machine, the factors that change over time include the difference in the friction coefficient due to the friction during the movement of the scanner, the change in the sliding force due to the dimensional change of the mechanical parts due to the heat from the exposure lamp, and the drive side Factors of the driving force fluctuation include changes in motor dynamic characteristics such as torque fluctuation due to winding resistance change due to energization of the scanner motor.If a constant voltage is applied, a constant rise, deceleration, and constant speed Tracing the speed profile is not always a factor. Due to such factors, as described above, when the scanner accelerates, the control value given as a fixed value does not always result in a stable constant speed within the approach distance.

According to the present invention, even when there is a fluctuation factor as described above, at the time of forward movement of the scanner, as shown by a broken line in FIG. As the data, at least one of the feedback control gain at the time of the latest scanner acceleration or the initial drive power applied to the motor at the start of the scanner is made variable from the maximum scanner speed until the leading edge of the document. As described above, since the scanner motor is under PWM control, the initial drive power is the PWM value applied to the motor.

As an actual application example, if the leading end position of the scanner is 450 pulses as described above, the encoder interrupt interval ECPT and the encoder interrupt interval ECPT up to that point are counted until the counter measuring the distance indicates 450. Minimum EC
Compare the PT (the maximum speed is the minimum ECPT since the ECPT is the inverse of the speed) and store the smaller value. When the leading edge of the manuscript is reached, the sampling and comparison of the ECPT are stopped.

FIG. 5 shows the flow at this time. By such an operation, a minimum ECPT can be obtained. The reciprocal of this value is the speed of the scanner.
The control value for the next scanner acceleration is calculated from the target speed value. In other words, the minimum ECPT is the EC of the target speed.
If the PT value is smaller than the PT value, it indicates that the speed overshoots during acceleration (A in FIG. 14), indicates that acceleration is excessive during acceleration, and it can be determined that more gradual acceleration is necessary. If the minimum ECPT is larger than the target speed ECPT (B in FIG. 14), it indicates that the scanner is not at a constant speed until the leading end position of the document. In this case, it indicates that more power is needed for acceleration.

The calculation may be performed after the current scan is completed and the scanner returns to the home position. Further, in this method, since the state of the previous scan is fed back to the acceleration control value of the next scan, there is no method other than performing the acceleration at the first scan operation with a predetermined initial value. For this reason, at the first time, a scan operation other than the copy operation is performed before the start of the copy operation, and is fed back to the subsequent copy operation, or the nonvolatile memory is mounted, and the value fed back at the time of aging at the time of factory shipment is used. What is necessary is just to store it in advance.

FIG. 6 is a table showing a PWM value and feedback control (PID control) corresponding to the error of the maximum speed from the target speed until the scanner passes the leading edge position of the document.
An example of the gain of the proportional term and the gain of the integral term are shown below. FIG. 7 shows a calculation flow. When the rate of the speed error is 115, it indicates that the speed is too high and an overshoot occurs. The new PWM is a value (initial value) determined in advance so as to accelerate from a state of stopping at the HP and to reach a constant speed under a general load condition from the leading end of the document under a general load condition. Kp is the gain of the comparison term of PID control determined in the same manner, and Ki is the gain of the integral term. The control amount to be adjusted is a value that is actually obtained by experiment.

In the second embodiment of the present invention, the position information of the scanner at the time of stoppage due to the fluctuation of the sliding load of the scanner optical system is reflected on the gain of the feedback control at the time of forward movement of the scanner. As described above, the target speed is programmed as a fixed value from acceleration to a constant speed. In the scan, the gain is set so as to reduce the speed error in a region of a constant speed. For this reason,
When a constant speed gain is applied as the acceleration gain,
The rising speed is not enough and it does not become constant at the leading edge of the document, or it accelerates too much and overshoots,
Similarly, it does not become constant speed. Therefore, in the second embodiment, the control gain for the acceleration operation when the scanner is started and the control gain for the constant speed operation are different.

That is, the speed at the time of acceleration can be controlled by the gain for acceleration, and the gain at the time of constant speed is controlled by the gain for constant speed. Thus, during acceleration, the target speed is quickly reached due to the dedicated gain. Also,
By switching the gain to a constant speed dedicated gain at a point where the target speed is predicted to be reached or at a point where the constant speed is reached, stable speed control can be performed in a constant speed range after the end of acceleration.

By the way, in the acceleration process, if the gain is simply changed when the target speed is reached, the following problems occur. As mentioned above, the target speed for acceleration is the same as the target speed for constant speed,
During acceleration, the integral term of PID control increases steadily. In general, the gain at the time of acceleration is set so as to provide a large feedback even with a small fluctuation. At a constant speed, the amount of feedback is usually smaller than at the time of acceleration. For this reason, the integral term at the time of acceleration is considerably large when the target speed is reached, and if the control is shifted to the constant speed control of the next stroke, the speed is increased by the enlarged integral term. In other words, after reaching a certain speed, a large overshoot occurs.

The curve shown by the broken line in FIG. 8 shows how the speed changes when the integral term during acceleration control is continuously entered into the constant speed control range. In the second embodiment,
In order to eliminate this inconvenience, the present invention is characterized in that the control is shifted from the acceleration control to the constant speed control, and the integral term accumulated during the acceleration is cleared at the same timing as when the gain is changed. A state in which such speed control is performed is shown by a solid line in FIG. By setting the integral term to 0 at the point where the gain is changed, there is no extra acceleration when a certain speed is reached, and no overshoot of the speed occurs.

As described above, by making the gains at the time of acceleration control different from those at the time of constant speed control, the acceleration time can be shortened at the time of acceleration, and at a constant speed, the oscillation of the control system due to a mismatch of the gain or the like. Stable feedback control becomes possible, and the speed curve becomes smooth by setting the integral term to 0 when transitioning from acceleration control to constant speed control, and a stable scanner operation without overshoot etc. Made it possible. The point at which the gain is switched and the integral term is cleared was obtained by experiments.
A fixed value may be used as a point where it is expected that the target constant speed has been reached, or a point where the speed measured by the encoder interrupt reaches the target speed may be used.

In the third embodiment of the present invention, speed information at a constant speed due to a change in the sliding load of the scanner optical system is reflected in a gain of feedback control at the time of forward movement of the scanner. If the scanner is stopped by the HP sensor, the scanner must be started at a constant speed within a distance of 50 pulses. Normally, the distance for these 50 pulses is referred to as a running distance. In normal control, the speed is constant within the approach distance, and even during traveling at a constant speed, the gain of the feedback control (for example, PID control) is determined as a fixed value in advance so that continuous oscillation of the scanner speed does not occur.

On the other hand, the sliding load of the scanner changes due to various factors. Differences in the friction coefficient of each machine when assembling the machine, the factors that change over time include the difference in the friction coefficient due to the friction during the movement of the scanner, the change in the sliding force due to the dimensional change of the mechanical parts due to the heat from the exposure lamp, and the drive side Factors of the driving force fluctuation include changes in motor dynamic characteristics such as torque fluctuation due to winding resistance change due to energization of the scanner motor.If a constant voltage is applied, a constant rise, deceleration, and constant speed Tracing the speed profile is not always a factor. Due to such factors, as described above, when the scanner travels at a constant speed, the control value given as a fixed value does not always result in a stable constant speed.

Here, in order to briefly explain the behavior of the gain and the control object, of the PID control, a proportional control using only P will be described as an example. As a method used when determining the proportionality constant (gain), there is a method called a limit sensitivity method. This is a method of gradually increasing the gain, observing the behavior of the control target, and determining the optimum gain. When the proportional gain is small, the vibration proceeds in the direction of convergence, and when the proportional gain is further increased, the vibration gradually becomes oscillatory. When the proportional gain is further increased, a state of continuous vibration in which the vibration is maintained is obtained. If the proportional gain is further increased from this state, the vibration becomes divergent, and the turbulence of the controlled object is increased. In the PID control, the stability limit is reached until the occurrence of the continuous vibration, and the value of the proportional control must be smaller than this value (FIG. 9).
Other control gains, integral gains, and differential gains are determined according to the period of the continuous vibration. When finally determining the gain, the gain is determined on the safe side, that is, in the direction in which the vibration is attenuated, in order to minimize the occurrence of divergent vibration even if there is disturbance, but if the gain is reduced, The control becomes insensitive and the vibration generated by disturbance or the like cannot be easily returned to a constant speed. In the above description, the behavior of the control target when the gain is changed is described. However, the same thing occurs when the gain is constant and the load of the control target changes.

In the third embodiment, the control is as sensitive to disturbance as possible as shown in FIG. 10 when the scanner moves forward, even if there is a fluctuation factor as described above, and a continuous vibration occurs. As the data at the previous scanner constant speed, so that it can be controlled in a state where it does not
The position information or the time when the scanner speed and the target speed exceed or fall below a certain value from the original position to the maximum scan position, which is detected by the moving distance detecting means, is read. A scanner optical system characterized in that feedback control is performed as a control value at a constant speed in the next forward scan according to position information or time information, and a gain of the feedback control system at a constant speed is variable. Is a control method.

As an actual application example, it is assumed here that the target speed at the time of running the scanner at a constant speed is v. Further, the allowable speed fluctuation rate is set to 2%. In such a state, if the speed of the scanner in a range where the speed must be controlled to be constant exceeds or falls below v ± 0.02v, it is determined that the gain is not appropriate as described above. Further, by detecting the position information when the value exceeds or falls below v ± 0.02v, whether the gain is too large and the vibration is in a divergent state, or the overshoot of the speed at the time of rising is fixed because the gain is too small. It can be determined whether or not the speed can be converged.

Then, if the speed of the scanner is v ± 0.
A method for determining whether the value exceeds 02v or below will be described. As described above, the position of the leading end of the scanner is 450.
If it is a pulse, the counter that measures the distance is 450
The interval ECPT of the encoder interrupt is constantly monitored from the time when the value exceeds the maximum value until the maximum scan position of the scanner is reached. The scanner speed is calculated from the ECPT value,
Compare with v ± 0.02v. Scanner speed is v +
Location information when exceeding 0.02v, and v-0.02v
Is stored in the memory. Also, the position information of the point where the speed deviation becomes maximum is stored in the memory. The position information is obtained by integrating the number of encoder interruptions from the home position of the scanner.

When one scan is completed, the position information stored in the memory is checked. The length of one scan is divided into the first half and the second half, and when the scanner speed is out of the range, the stored position information is more in the first half.
It is determined whether the number is large in the latter half or measured in the entire scan. If it is large in the first half, it indicates that the overshoot at the start of the scanner cannot be converged and the gain is too small, and if it appears overall, the gain is large and continuous vibration is occurring, or the vibration is diverging Can be determined. Here, when the maximum value of the speed deviation is large in the latter half, it indicates that the vibration is diverging with time and the gain is too large.

As described above, case 1 (FIG. 10 (a)) indicates that the gain is too small, and case 2 (FIG. 10 (b)) indicates that the gain is too large to determine that the continuous vibration is occurring. The case where it is considered to be in the divergent state is referred to as case 3 (FIG. 10C). In each case, the gain is calculated and the gain is corrected at the next scan. An example is shown in the table of FIG. Here, only the proportional gain is made variable, but it is also possible to calculate the period of the position information deviating from the allowable speed and feed it back to the integral gain and the differential gain. FIG. 12 is a flowchart for storing the position information of the point deviating from the allowable speed and the position information of the point with the maximum speed deviation.

[0041]

As described above, according to the present invention, when the acceleration control of the forward movement of the scanner optical system is performed, even if the acceleration profile fluctuates due to the fluctuation of the sliding load, the scanner optical system remains constant. Acceleration control to speed can be performed smoothly,
Therefore, a good copy result without extension of the leading edge image of the copied image can be obtained irrespective of the variation in the sliding load of the scanner optical system. Further, when performing acceleration control of the forward movement of the scanner optical system, the acceleration time can be reduced, and the copy speed can be improved. In addition, stable control of acceleration and constant speed becomes possible, and when moving from acceleration to constant speed, the speed curve becomes smooth, and the vibration of the scanner optical system and, consequently, the vibration of the image can be eliminated. Further, when performing acceleration control of the forward movement of the scanner optical system, even if the speed in a certain speed range fluctuates due to a change in the sliding load, the gain is repeatedly corrected so as to approach the certain speed at the next scan. As a result, the speed of the scanner optical system becomes constant, so that a good copy result without expansion, vibration, etc. of the copied image can be obtained regardless of the fluctuation of the sliding load of the scanner optical system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control circuit of a scanner optical system.

FIG. 2 is a diagram illustrating a waveform example of PWM control.

FIG. 3 is a diagram showing a timing chart of a mode 3;

FIG. 4 is a diagram showing a timing chart of a mode 1;

FIG. 5 is a flowchart showing an operation for obtaining a minimum ECPT.

FIG. 6 is a table showing a PWM value and various gains corresponding to an error of a maximum speed with respect to a target speed until the scanner passes the original document top position.

FIG. 7 is a flowchart showing a calculation operation for obtaining the value of FIG. 6;

FIG. 8 is a speed-time characteristic diagram showing a change in speed when an integral term during acceleration control is continuously entered into a constant speed control region in a forward operation of the scanner optical system.

FIG. 9 is a control block diagram of proportional control using only P of the PID control and a diagram showing vibration characteristics depending on the magnitude of a proportional gain.

FIG. 10 is a speed-time characteristic diagram of a scanner optical system that varies depending on the magnitude of a gain.

11 is a table corresponding to FIG. 10 and showing a new gain to be corrected at the next scan.

FIG. 12 is a flowchart for storing the position information of the point deviating from the allowable speed and the position information of the point with the maximum speed deviation.

FIG. 13 is a schematic configuration diagram of a conventional scanner optical system.

FIG. 14 is a perspective view of the scanner optical system shown in FIG.

FIG. 15 is a speed-time characteristic diagram illustrating acceleration control of a reciprocating operation of the scanner optical system.

FIG. 16 is a diagram showing different operation characteristics in acceleration control of the forward operation of the scanner optical system.

FIG. 17 is a speed-time characteristic diagram of a forward operation of the scanner optical system.

FIG. 18 is a speed-time characteristic diagram of a forward operation of the scanner optical system.

FIG. 19 is a diagram illustrating various vibration characteristics by acceleration control of a forward operation of a scanner optical system.

[Explanation of symbols]

 2 Scanner optical system 14 DC motor for conveyance 16 HP sensor 20 Microcomputer 21 Programmable interval timer 22 Encoder 23, 25 Buffer 24, 27 Oscillator 26 Flip-flop 28, 29 Gate circuit

Continuation of the front page (51) Int.Cl. ⁷ identification code FI G06T 1/00 G06F 15/64 325F H04N 1/04 105 (58) Investigated field (Int.Cl. ⁷ , DB name) G03B 27/50 G03G 15/04 G05B 11/36 G06T 1/00 H04N 1/04 105

Claims (5)

(57) [Claims] A scanner optical system capable of reciprocating operation; a scanner transport motor for transporting the scanner optical system; a moving speed detecting means for detecting a moving speed of the scanner optical system; A moving distance detecting means for detecting a moving distance of the system, wherein the moving speed detecting means and a distance detecting means for stabilizing a predetermined scanning speed by a predetermined position when the scanner optical system moves forward. In a series of scanner optical system forward movement control in which the result obtained by the means is feedback-controlled to the power applied to the motor, and control is performed so as to move at a constant speed when the reference position is reached. Reads the scanner's maximum scanner speed up to the detected document leading edge position or a certain point before the document leading edge A feedback control is performed as an acceleration control value in the next forward scan according to the scan speed, and a gain of the feedback control system in acceleration is made variable. 2. The method according to claim 1, wherein the feedback control during acceleration is P
2. The acceleration control method for a scanner optical system according to claim 1, wherein the acceleration control is performed by an ID control method. 3. A scanner optical system capable of reciprocating operation, a scanner transport motor for transporting the scanner optical system, a moving speed detecting means for detecting a moving speed of the scanner optical system, and the scanner optical system. A moving distance detecting means for detecting a moving distance of the system, wherein the moving speed detecting means and a distance detecting means for stabilizing a predetermined scanning speed by a predetermined position when the scanner optical system moves forward. A series of scanner optical system forward movement controls that perform feedback control of the result obtained by the means to the power applied to the motor and perform control to move at a constant speed when the reference position is reached. In the control method using at least the integral term (I), the PID from the stop position of the scanner to the position of the leading edge of the original to a certain arbitrary position is small. At least one kind of gain value is different from the same kind of gain value used for control after the position, and the value of the integral term up to that point is cleared at the position. Scanner optical system control method. 4. A scanner optical system capable of reciprocating operation, a scanner transport motor for transporting the scanner optical system, a moving speed detecting means for detecting a moving speed of the scanner optical system, and the scanner optical system. A moving distance detecting means for detecting a moving distance of the system, wherein the moving speed detecting means and a distance detecting means for stabilizing a predetermined scanning speed by a predetermined position when the scanner optical system moves forward. In a series of scanner optical system forward movement control in which the result obtained by the means is feedback-controlled to the power applied to the motor, and control is performed so as to move at a constant speed when the reference position is reached. The speed of the scanner and the target speed between the detected leading edge position and the maximum scanning position exceed or fall below a certain value. The position information or time at the time of reading is read, and feedback control is performed as a control value at a constant speed in the next forward scan according to the position information or the time information, and the gain of the feedback control system at a constant speed is obtained. The control method of the scanner optical system, characterized in that it is variable. 5. The feedback control at the time of acceleration, wherein P
5. The control method for a scanner optical system according to claim 4, wherein the control is performed by an ID control method.