JPH03289644A - Scanner controller - Google Patents

Abstract

PURPOSE:To prevent the image at the head of an original from extending and vibrating by performing feedback control so that a scanner is started according to position information at the time of the inversion of the scanner and position information at the time of its stop and then reaches a constant speed at the head position of the original. CONSTITUTION:The scanner forward driving electric power for the forward operation of the scanner and the proportional gain of the feedback control are set corresponding to the position difference HP-Rr of a scanner position Rr from a reference position HP. Feedback control means 20 and 21 energizes an electric motor M7 in the scanner forward driving direction according to the set scanner forward driving electric power and energizes and controls the electric motor M7 according to the set proportional gain so that the speed detected by a speed detecting means 20 reaches a target value. Therefore, even if the scanner overruns and stops beyond the reference position HP, the scanner is controlled to the constant speed at the original head position. Consequently, the image at the head neither extends nor vibrates.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scanner control device for controlling the drive of a scanner of an image forming apparatus, and more particularly to a scanner control device for controlling the acceleration of a scanner.

[Conventional technology]

FIG. 7a shows a schematic structure of a general optical system of a conventional image forming apparatus, and FIG. 7b shows a perspective view thereof.

Referring to FIG. 7a, a scanner optical system 2 is provided below the contact glass 1 on which a document (not shown) is set, and an image formed by light reflected from the document is transmitted to the scanner optical system 2. The image is formed on a drum-shaped photoreceptor 3 via the . The scanner optical system 2 includes a first carriage 51 comprising an illumination light source 2a, a reflection plate 2b, a first mirror 2c, etc., a second carriage 52 comprising a second mirror 2d, a third mirror 28, etc., and an imaging lens 2f. , a fourth mirror 2g, etc. 2h is dustproof glass. The first carriage 51 and the second carriage 52 are driven for reciprocating scanning by a DC motor M7 at a speed ratio of 2=1 so that the length of the optical path reflected from the document does not change during scanning.

This will be explained with reference to FIG. 7b. A drive wire 61 coupled to the scanner optical system 2 is wound around a pulley 60 fixed to the shaft of a DC motor M7. The drive wire 61 is connected from one end 61a to a stand pulley 62. Drive pulley 63 coupled to second carriage 52 . Turn pulley 64. A blanket pulley 66, a blanket 67 coupled to the first carriage 51, a drive pulley 63. It is connected to the other end 61b passing through the tightener pulley 68 to form a closed loop.

HPI shown in FIG. 7b is a switch (photo sensor) that detects the home position of the scanner. Similarly, RP
I is a limit switch that detects one forward scanning end position of the scanner, and RP2 is a limit switch that detects another forward scanning end position. Although not shown in this drawing, the variable magnification mechanism (that is, the lens) is also provided with a photosensor HP2 for detecting the home position. This switch is turned on when the lens is in the home position and the magnification position. The reason why the forward scanning end position is detected by two limit switches is because when the scanner performs full scanning, the position of the variable magnification mechanism, especially the lens, changes and the scanner collides with it. This is to protect it. The RPI switch is provided at the forward scanning end position, and the RP2 switch is provided at the variable magnification mechanism.

In such a configuration, the scanner optical system 2 is driven rightward from the HP state as schematically shown in FIG. 7a to expose and scan the document surface.

After completing the exposure scan, the scanner optical system 2 moves back toward the home position again. During the backward movement of the scanner optical system 2, it is generally driven faster than during the forward movement, and deceleration control is performed when the scanner optical system 2 approaches the home position HP. Then, when the HPI detects the home position HP, the rotation direction of the motor M7 is reversed (scanner backward movement direction).
By switching from forward rotation (scanner forward direction),
This is to return to the home position HP from the overrun position.

Control of the operation of the scanner optical system 2 will be described in detail below.

First, considering one cycle of forward and backward movement of the scanner optical system 2, it becomes as shown in FIG.

In FIG. 8, the horizontal axis is time, and the vertical axis is the rotational speed of the scanner drive motor (or the speed of the first carriage 51). The broken line is the target value, and the actual change in rotational speed is the solid line.

Here, the deceleration control operation during the backward movement will be explained with reference to FIG. In FIG. 9, the broken line is the target speed. - Operation characteristic A shown by the dotted chain line indicates a case where the scanner has a large sliding load and performs deceleration follow-up control with a constant feedback gain, but the overshoot of the deceleration amount is too large and the scanner stops in front of the HP sensor. . In addition, operating characteristic B shown by the solid line shows that when the scanner sliding load is light and deceleration follow-up control is performed with a constant feedback gain, the scanner speed does not decrease even when the brake is applied and the HP sensor passes. This shows a case where even if reverse rotational power is applied to the motor by passing the sensor, the HP sensor is considerably overrun and the motor is stopped.

In Figure 10, the horizontal axis shows distance, and the scanner is
A case where the scanner stops in front of the P sensor and a case B when the scanner stops after significantly overrunning the HP sensor are shown. Further, FIG. 10 also shows a situation where the matching of the load and the feedback gain of the scanner control is optimal, and the speed near the HP becomes 0 and the machine stops.

[Problem to be solved by the invention]

When starting the next scan from this state, the 11th
As shown in Figure 1sC, the speed must be constant until the leading edge of the document on the contact glass.However, in operating characteristic A shown by the dashed-dotted line, the sliding load on the scanner is large and the acceleration is controlled with a constant feedback gain. If this is done, the acceleration cannot be completed until the leading edge of the document reaches the position, and the speed cannot be maintained at a constant speed.

Furthermore, the operating characteristic B indicated by the broken line has a light sliding load on the scanner.

When acceleration control is performed with a constant feedback gain,
The speed tends to overshoot and the scanner vibrates as it accelerates.

In both cases A and B, the constant speed control at the leading edge of the original cannot be performed normally, and the leading edge of the copied original image is elongated or is copied as a blurred image that looks like it is vibrating.

This is mainly due to variations in the sliding load, but the sliding load of the scanner changes due to various factors. For example, there are differences in the friction coefficients of each machine during machine assembly, changes over time due to fluctuations in sliding force due to friction during scanner movement, and fluctuations in driving force on the drive side due to windings due to energization of the scanner motor. There are changes in motor dynamic characteristics such as torque fluctuations due to resistance changes, and this is a factor that does not necessarily trace a constant rise, deceleration, or constant speed profile if a constant voltage is applied.

In addition, some machines are able to inspect the sliding load of each machine at the time of shipment from the factory and set the appropriate gain for each machine so that the target speed is reached at the leading edge of the document. Even if it is possible to absorb variations in dynamic load, it cannot absorb fluctuation factors due to changes over time or factors due to fluctuations in driving force.

As mentioned above, due to the variable factors, the acceleration control of the scanner does not end before the scanner reaches the leading edge of the document, and the scanner does not reach a constant speed at the leading edge of the document, resulting in stretching and vibration of the image during copying. The purpose is to prevent such things.

[Means for Solving the Problems 1] The scanner control device of the present invention includes: a scanner (51) capable of reciprocating operation; an electric motor (M7) that drives the scanner (51) in forward/reverse rotation; signal generating means (22) for generating electric pulses with a frequency proportional to the rotational speed of the electric motor (M7);
rotational direction detection means (20) for detecting the rotational direction of the scanner; speed detection means (20) for detecting the speed (V) of the scanner (51) by electric pulses generated by the signal generation means (22);
20); Position information detection means (20) that detects position information of the scanner (51) by electric pulses generated by the signal generation means (22); During the backward movement of the scanner (51), the scanner (51) returns to the reference position (HP); ) Scanner position II where the moving direction of the scanner (51) is reversed after crossing
Position difference (HP - R) from the reference position (HP) of (Rr)
r), the position difference (HP −Rr) is large (
an adjustment means (20) for setting the scanner forward drive power (PWM) and the proportional gain (Kp) of feedback control small; and the scanner forward drive power (PwM) set by the adjustment means (20) The electric motor (M7) is energized in the driving direction, and the proportional gain (set by the adjusting means (20)) is feedback control means (20, 21) for controlling the energization of the electric motor (M7) based on p);

Note that symbols in parentheses indicate corresponding elements in the embodiments described later.

[Action 1] According to this, the feedback control means (20, 21)
controls the electric motor (M7) so that the detected speed (V) detected by the speed detecting means (20) matches the target value (MO), so the speed (V) of the scanner (51) reaches the target value (MO).
MO). but,
In the backward movement of the scanner (51), if the sliding load of the scanner (51) is light and the scanner (51) is stopped after significantly overrunning the reference position II (HP), when the scanner (51) is moved forward in the primary direction, for example, (51) cannot be kept at a constant speed at the leading edge of the document.

In the present invention, when the scanner (51) makes a backward movement, the rotational direction detection means (20) detects that the moving direction of the scanner (51) has been reversed after the scanner (51) crosses the reference position if (HP). Position when detected (Rr)
is detected by the position information detection means (20), and the adjustment means (20
) corresponds to the position difference (HP - Rr) from the platform position (HP) of scanner position 1 (Rr), and the position difference (HP - R
r) is large, the scanner forward drive power (PWM) and the proportional gain (Kp) of the feedback gain control are set small when the scanner (51) moves forward next time, and the feedback control means (20, 21) The electric motor (M7) is energized in the scanner forward drive direction based on the scanner forward drive power (PWM), and the detected speed (■) detected by the speed detection means (20) and the target are determined based on the proportional gain (Kp). The electric motor (M7) is energized and controlled so that the value (MO) matches.

Therefore, even if the scanner (51) exceeds the reference position (HP) and stops, the scanner (51) can be controlled to maintain a constant speed at the leading edge of the document, so that the image at the leading edge does not stretch or vibrate. This results in stable copying operations without any problems.

[Means for Solving the Problem 2] The scanner control device of the present invention includes: a scanner (51) capable of reciprocating operation; an electric motor (M7) that drives the scanner (51) in forward/reverse rotation; signal generating means (22) that is coupled to the
The electric pulse generated by the scanner (51)
) Speed detection means (20) for detecting the speed (V) of the scanner (51); Position information detection means (20) for detecting position information of the scanner (51) by electric pulses generated by the signal generation means (22); Scanner (51) When the position information of the scanner (
Corresponding to the position information (RO) when the scanner (51) stops in the backward movement of 51), if the value is large, the scanner forward drive power (PWM) and the proportional gain (Kp) of the feedback control are increased. Adjustment means to be set (
20); and the electric motor (ear 7) in the forward drive direction of the scanner using the forward drive power (PVM) set by the adjusting means (20).
is energized, and the detected speed (
Adjustment means (2) so that V) and target value (MO) match.
0) based on the proportional gain (Kp) set by the electric motor (
feedback control means (20,
21) ;

[Effect 2] According to this, the sliding load of the scanner (51) is large during the backward movement of the scanner (51), and the reference position! (HP)
If the scanner (51) is stopped before reaching this point, for example, the scanner (51) cannot be kept at a constant speed at the leading edge of the document when the scanner (51) is driven forward next time.

In the present invention, when the scanner (51) makes a return operation, the position information detection means (20) detects the position information (Ro) at which the scanner (51) has stopped, and the adjustment means (2o) detects the position information (Ro) at which the scanner (51) has stopped. The position difference (R, -H) corresponds to the position difference (Ro-HP) in the forward direction from the reference position (HP).
P) is large, the scanner forward drive power (PWM) and the proportional gain (Kp) of the feedback gain control are set large when the scanner (51) moves forward next time, and the feedback control means (20, 21) The electric motor (M7) is energized in the scanner forward drive direction based on the scanner forward drive power (PWM), and the detected speed (V) detected by the speed detection means (20) and the target are determined based on the proportional gain (Kp). The electric motor (M7) is energized and controlled so that the value (MO) matches.

Therefore, even if the scanner (51) stops before reaching the reference position II (HP), the scanner (51) can be controlled to have a constant speed at the leading edge of the document, so that the image at the leading edge does not stretch or vibrate. The copy operation is stable without any lag.

Other objects and features of the present invention will become clear from the following examples with reference to the drawings.

〔Example〕

The general mechanism of the scanner according to the embodiment of the present invention is similar to the conventional scanner shown in FIGS. 7a and 7b, but the configuration of its control system is different.

FIG. 1 shows a schematic configuration of the control system of this embodiment.

This control system is mainly composed of a microcomputer 20 (hereinafter referred to as CPU).
20 uses μPD7811G.

Further, a programmable interval timer 21 is connected to the CPU 20, and a μPD8253C is used as the programmable interval timer 21.

A DC motor M7 for conveying the scanner optical system 2 is.

CPU via drive transistors Tri to Tr4
20 and is driven and controlled. In the DC motor M7, transistors Tri and Tr3 are on, T r 2 , T
Rotationally driven clockwise (CW) with r4 off, transistors Tr1 and Tr3 off,
Tr2. While Tr4 is on, it is rotated in the long-term direction (CCV). Note that the DC motor M7 is rotated counterclockwise (
CCW), the scanner optical system 2 is set to perform a double-movement operation.

A rotary encoder 22 is connected to the DC motor M7, and generates two pulse signals with different phases depending on the amount and direction of rotation of the DC motor M7. One is the A-phase encoder pulse ENCA, and the other is the B-phase encoder pulse ENCB.

The A-phase encoder pulse ENCA is input to the counter input terminal CI of the CPU 20 via the buffer 23. The CPU 20 measures the pulse interval of the A-phase encoder pulse ENCA using a counter φ12 (oscillation frequency of the oscillator 24 of the CPU 20 x 1/12) built into the CPU. Further, the input signal to the input terminal CI of this counter φ12 is an interrupt. This interrupt causes the CPU20
is the encoder interval measurement data (TIMER/EVE
NTCOUNTERCAPTURE REGISTER
Based on this data, calculate the rotation speed (scan speed) of DC motor M7, calculate the deviation from the target rotation speed (target speed), and calculate the motor control amount by proportional/integral control calculations. (ON time of pulse width modulation PWM control)
calculation and output (programmable interval timer 2
1).

The encoder pulse ENCA is input to the clock terminal CLK of the D flip-flop 26 via the buffer 23,
The encoder pulse ENCB is input to the D terminal of the D flip-flop 26 via the buffer 25. The output Q of the D flip-flop 26 (signal indicating the rotation direction of the DC motor M7) is input to the input terminal PC7 of the CPU 20,
The PU 20 determines the rotation direction of the DC motor M7 based on this output Q.

The programmable interval timer 21 includes an oscillator 27.
is connected to obtain a clock signal. Further, the DC motor M7 is controlled by PWM control, and this PWM signal is generated by the timer 21.

The programmable interval timer 21 has two counters, counter O and counter 1. counter O
PWM cycle data is loaded into the counter O, and a PWM cycle square wave is output from the output ○UTO of the counter O. This 0
Zhen is the gate input of counter 1. In addition, the ON time data of the PWM signal is stored in the counter l.
20, and a one-shot output synchronized with the PWM cycle is output from ○UTI. The output from OUT 1 controls the transistor Tr 3 or Tr 4 in a ◯N/◯FF manner via gate circuits 28 and 29.

FIG. 4 shows a waveform example of the above-mentioned PWM control. This figure shows that even if the ON time toe changes, the PWM period t, (=toN+top F) is constant.

Incidentally, the μPD8253C used as the programmable interval timer 21 has six program timer modes from mode O to mote 5, but mode 3 and mode 1 are set in this embodiment. counter O
is set to mode 3 (square wave rate generator),
Counter l is set to mode 1 (programmable one-shot).

Since the PWM period is constant, it is only necessary to load the count number of counter=O once. And PWM Lo
Every time N time is changed, the count number of counter O is loaded.

Mode 3 and mode 1 will be explained below.

FIG. 5 shows a timing chart for mote 3 (square wave rate generator). In this case, it operates as an n-divided counter of the input clock.

In addition, when the count number is even, the duty ratio is 1/
2, and the duty ratio when the count number is odd is (
n-1)/2n. For example, when the count number n=5, the duty ratio is 215 (active low).

That is, when this mode is selected by the control word input from CP TJ-20, 0UTO=
1, and load the count number with GATE L = 1. This starts counting. When the count number is even, the first half of the count is 0UTO =
1. The second half is ○UTO=O. When the count number is odd, the first half of the count (n+1)/2 is ○UTO=
1, the second half (n-1)/2 becomes 0UTO=O. G again
When ATE1=0, ○UT synchronizes with the falling edge of ATE1.
O=1 and counting stops, then GATE 1
= When it becomes king, counting will restart from the initial value.

If a count number is loaded during counting, a new count will start from the next cycle. If the count is an even number, the counter is decremented by 2; if it is an odd number, when UTO=1, the counter is decremented by 1 at the first clock, and from the second clock, the counter is decremented by 2.

FIG. 6 shows a timing chart of mode 2 (programmable one-shot) of the programmable interval timer 21. This outputs a one-shot pulse (active low) of a specified length.

When this mode 1 is selected by the control word input from the CPU 20, 0UTO=1, and after loading the count number, a count triggered by the rising edge of GATE 1 is started.

During counting, 0UTO=0, and when counting ends, 0UTO=1 again. In other words, it is an active low one-shot output whose pulse width corresponds to the count number. If a trigger is applied during counting (when GATE 1 is changed from 0 to 1), counting starts again from the initial value. Note that even if the count number is rotated during counting, it will not affect the current count, but when a trigger is applied, counting will start with a new number of columns.

As described above, by inputting PWM cycle data using timer O and using the data as gate input of timer 1 to form PWM on-time data in timer 1, the output of 0TJTl, which is the output of timer 1, is The pulse is P
It becomes WM data.

A control flowchart of the CPU 20 is shown in 2nd aCj4. First, when the power is turned on (Step 1: the word "step" will be omitted hereafter), the scanner is moved slowly to clear timers, flags, etc. and detect the exact position of the scanner. Initialization is performed to set the location detected by the IP sensor as the reference address (home position) for all operations (2). Next, register PWM has ρ
Initialize ρ in wm and Kp, respectively (3). Note that pwm is a value predetermined at the time of shipment from the factory so that the scanner accelerates from a stopped state to HP and reaches a constant speed until the leading edge of the document, and kp is determined in the same way, and is a value determined in advance by the proportional gain of the control formula described later. It is. After completing step 3, wait until a start instruction is given (4).

When a start instruction is given, the scanner performs forward movement control (
5). "Forward motion control" (5) performs acceleration control until the scanner reaches a predetermined speed, and then performs constant speed control of the incoming scanner.

When the sensor RPI detects that the scanner has reached the return position (6), "return control" of the scanner is performed (7). “Forward control” (5) to “Return control” (
Moving to step 7), the motor M7 is driven to reverse rotation, and the scanner is controlled at a constant speed faster than in "forward motion control" (5), and when the HP position approaches, deceleration control is performed. and,
A flag SP, which is set in "return control" (7) to be described later, and indicates whether the scanner has stopped before detecting the HP position is checked (8). If SP is not l in step 8 and the HP position is detected by the sensor HPI (9), the scanner's "stop control" is performed (10) "stop control J (10
), the motor is driven to reverse rotation again and then stopped. Further, when 5P=1°, that is, when the scanner stops before detecting the HP position, "stop control J (10) is not performed.

Next, register R is set in "return control" (7) or "stop control J" (10), which will be described later.

12), and corresponding to this value, set the initial drive power to be applied to the motor when the scanner is next driven, that is, the initial value of PWM to be applied to the motor, as shown in Table 112). Then, the gain of the control formula corresponding to register R8 is set (13).

Table 1: When the specified number of reciprocating controls are completed, the process returns to step 3 and waits until a start instruction is given. If the specified number of reciprocating controls have not been completed, the process returns to step 5 and performs "forward control" again (5 ) (14).

Figure 2b shows rCI interrupt processing by encoder interrupt.
The flowchart is shown below. In this "C-work interrupt processing", first, the timer Ts used for determining the scanner stop is started (21), then the measured data of the encoder interval is read (22), and the speed V of the motor M7 is calculated based on this data. (23).

Furthermore, the deviation MO-V between this speed V and the target value MO is detected, the gain Kp is read (24), and PWM calculation is performed based on the deviation MO-■ and the gain KP (25).

Here, this PWM calculation will be explained.

In this embodiment, the sliding load of the scanner optical system is estimated from the position information of the scanner at the time of reversal or stop, and the feedback control (PID) of the acceleration control during the next forward movement of the scanner is performed.
This is reflected in the gain of control) so that when the scanner is restarted, the scanner reaches a constant speed at the leading edge of the document. That is, in this embodiment, in order to detect load fluctuations, an inversion address or a brake address as shown in FIG. The initial PWM value at the time of transition from stoppage to forward motion is determined as a fixed value as shown in Table 1 mentioned above, and calculation is performed. Each address will be explained below.

(1) Reversal address: When the scanner returns to the home position, the reverse rotation brake is applied until the rotation changes from reverse to forward, but this is the address of the unconventional scanner where the direction of rotation changes from reverse to forward.

(2) Brake address: Stop address when the scanner is heavily loaded and stops short of the platform.

Here, the address of the home position HP is set to 400 pulses, and during forward movement, the scanner moves and the encoder 22
One pulse is output from the address and the address is added every four. Also, at the time of return, the address is subtracted every time one pulse is input/output from the encoder 22. Note that whether the movement is forward or backward is determined based on the direction of rotation of the scanner motor M7.

The reverse address is detected after the scanner passes the sensor HPI. For example, scanner motor M7 with 390 pulses
When the rotation changes from reverse rotation to forward rotation, the reversal address is 39.
It becomes 0.

Brake address is sensor HP due to excessive braking.
This is address information for determining at which position before I the vehicle has stopped. This value takes a value of 400 nolus or more.

The PWM value given to the scanner motor, that is, the manipulated variable Yn is expressed by the following control equation.

Yn=K p X en+(1/ K i )XΣe
n where en is the deviation of the current speed from the target value (en = M 0 - V). Note that the target values are set separately in each of the forward movement and backward movement controls in the main routine (FIG. 2a).

When the PWM calculation is completed, data is loaded into the programmable interval timer 21 based on this value and the process returns (26).

FIG. 2c shows a flowchart of "return control" (7) shown in FIG. 2a.

First, it is checked whether the current address Ad of the scanner is greater than or equal to a predetermined value A1 (71). If so, the timer Ts used for determining the stoppage of the scanner is cleared 72), and "constant speed control" is performed (73). Also, how to read the scanner address.

The address of the HP is set to 400 pulses, the pulses output from the encoder 22 are counted by the CPU 20, and the current position of the scanner can be accurately grasped by counting up when the scanner moves forward and counting down when moving backward.

If the address Ad is less than the predetermined value A1, the flag SP is set to O (74), and the timer Ts is checked to see if it has timed out (75). - In this way, when the address Ad is A1 or more, "constant speed control J (73) is executed, but if the address Ad is
If the value becomes less than 1 and the timer Ts does not time out, "deceleration control J (76) is executed.

If the scanner is detected by the HP without the timer Ts exceeding its time, the process proceeds to "stop control" (1 in Figure 2a).
0).

By the way, the timer Ts is restarted each time there is an encoder input (pulse) by the rCI interrupt process shown in FIG. do not. However, in "return control" (7), when the scanner stops or reaches an extremely low speed that can be considered stopped, the encoder cycle becomes Ts or more (infinite when it stops completely), and the rCI interrupt processing (
2b) is executed at a cycle longer than Ts, or is not executed at all (in the case of a complete stop), so the timer Ts times out.

Then, the CPU 20 assumes that the scanner has stopped before the HP, and sets the flag SP to 177).
Write the address of the stop position to register RO. Next, in the homing process, it is driven again, moved toward the home position, and stopped at the home position.79)-
Return to main routine.

FIG. 2d shows a flowchart of the "stop control" (10) shown in FIG. 2a.

When it is detected that the scanner has passed the double-movement sensor HPI (9 in Figure 2a), the PWM value is set to apply a reverse brake in the same way as for column movement to stop the double-drive movement of the scanner. Output (101). When the scanner is reversed from reverse rotation to forward rotation (from double drive direction to inter-column movement direction) (102), the address of the scanner at the point where this rotation changed, that is, the reverse address, is written to register Rr (103), and the scanner Stop motor M7 (10
4). Then, register R written in step 103
The distance from when the scanner reverses until it stops is determined by the value of r (
The value obtained by adding the pulse amount) Id (Id is assumed to be constant) is written in the register Ro (105), and the process returns to the main routine.

In Figure 2e, "Initial drive setting" (12) shown in Figure 2a
The flowchart is shown below.

Here, the initial drive value (P
WM operation initial value) is determined.

First, "return control" (7) or "stop control" (1)
Read the value written to register R,) at step 0).12
1) If RO is less than 380 pulses, register P
Set pwm-25 for WM122), if it is 380 pulses or more and less than 385 pulses, set pwn+-15123), if 385 pulses or more and less than 390 pulses, set pwm -5 12U, 390 pulses or more 400 If it is less than the pulse, set pwtm±0 to 1
25) If it is 400 pulses or more and less than 405 pulses, set ρw+10126) If it is 405 pulses or more and less than 410 pulses, set pwm+2012
7) If it is 410 pulses or more and less than 415 pulses, set pwm+30 (128), and if it is 415 pulses or more, set pw+m+40 (129).

FIG. 2f shows a flowchart of "gain setting" (13) shown in FIG. 2a.

Here, the proportional gain of the above-mentioned feedback control (PID control) when the scanner starts next time is determined in accordance with the position information when the scanner is reversed (reverse address) or the position information when it is stopped (brake address). .

First, "return control" (7) or "stop control" (1)
131 Read the value written to register Ro at step 0).
), if Ro is less than 380 pulses, register Kp
Set kp-3 to 132), set ρ-2 to 380 pulses or more and less than 385 pulses133
), 1 if 385 pulses or more and less than 390 pulses
Please set tp-1134), 390 pulses or more4
If it is less than 00 pulses, set kp±0135)
, kp+2 if 400 pulses or more and less than 405 pulses
Please set 136), if it is 405 pulses or more and less than 410 pulses, set kp+4137), 410
If the pulse is greater than or equal to 415 pulses, set kp+6 (13g), and if it is greater than or equal to 415 pulses, set kP+8 (139).e The above is an outline of the control flowchart in the CPU 20.

In other words, in this embodiment, the position information (
Based on the position information, the scanner is then started and feedback control is performed so that the scanner reaches a constant speed at the leading edge of the document (p Io * JflJ) (1 ) Determine the initial value PWM O, J: and the proportional gain Kp.

In addition, in this embodiment, feedback control (PID control)
Among the gains, only the proportional gain is made variable, but other gains may be changed.

〔Effect of the invention〕

As described above, according to the present invention, the scanner (51) is the reference position! Even if it exceeds (HP) and stops, the scanner (5
1) can be controlled so that the speed is constant at the leading edge of the document, so the image at the leading edge does not stretch or vibrate, resulting in a stable copying operation.

Also, the scanner (51) is in the reference position! Even if the scanner (51) is stopped before reaching (HP), the scanner (51) can be controlled to maintain a constant speed at the leading edge of the document, so the image at the leading edge does not stretch or vibrate, resulting in stable bee movement. becomes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a control system according to an embodiment of the present invention. FIG. 2a is a flowchart showing the control operation of the CP 20 shown in FIG. FIG. 2b is a flowchart showing the operation of CI interrupt processing by the CPU 20 shown in FIG. FIG. 2c is a flowchart showing the contents of "return control" (7) shown in FIG. 2a. FIG. 2d is a flowchart showing the contents of "stop control" (lO) shown in FIG. 2a. Figure 2e shows the "initial drive settings" (12) shown in Figure 2a.
FIG. FIG. 2f is a flowchart showing the contents of gain setting j (13) shown in FIG. 2a. FIG. 3 is a graph showing the relationship between scanner characteristics and addresses. 1. FIG. 5 is a time chart showing the PWM control output of the programmable interval timer 21 shown in FIG. 1. FIG. 5 is a time chart of mode 3 of the programmable interval timer 21 shown in FIG. 7 is a time chart of mode 1 of the programmable interval timer 21 shown in FIG. 7. FIG. 7a is a side view showing an outline of the mechanism of a conventional scanner, and FIG. FIG. 9 is a graph showing the operating characteristics of a scanner in one reciprocating cycle. FIG. 9 is a graph showing the deceleration control characteristics of a conventional scanner. FIG. 10 is a graph showing the case where a conventional scanner stops at a fixed position. (above) and when stopped before the fixed position (
It is a graph showing the characteristics when the vehicle stops after exceeding the normal position (middle) and when it stops after exceeding the normal position (bottom). FIG. 11 is a graph showing the operating characteristics of a conventional scanner. 1: Contact glass 2: Scanner optical system 2a
: Illumination light source 2b Two reflecting plates 2c: First mirror 2d: Second mirror 2e: Third mirror 2f: Imaging lens 2g = Fourth mirror
2h: Dust-proof glass 51: First carriage (scanner) 52: Second carriage HPI: Home position sensor RPI, RP2: Return position sensor M7: Scanner motor (electric motor) 20: CPU (rotation direction detection means, speed detection means. Position information Detection means, : 11 adjustment means) 21: Programmable interval timer (20, 21
: Feedback control means) 22: Encoder (signal generation means)

Claims (2)

[Claims] (1) A scanner capable of reciprocating operation; an electric motor that drives the scanner in forward/reverse rotation; a signal generating means that is mechanically coupled to the electric motor and generates electric pulses with a frequency proportional to the rotational speed of the electric motor; Rotational direction detection means for detecting the rotational direction; Speed detection means for detecting the speed of the scanner using electric pulses generated by the signal generating means; Position information detection means for detecting position information of the scanner using electric pulses generated by the signal generating means. Means: Corresponding to the positional difference from the reference position of the scanner position where the direction of movement of the scanner is reversed after the scanner crosses the reference position during the backward movement of the scanner, if the positional difference is large, the scanner forward drive power and feedback control are an adjusting means for setting a small proportional gain; and energizing the electric motor in the forward driving direction of the scanner with the forward driving power set by the adjusting means so that the detected speed detected by the speed detecting means matches the target value. A scanner control device comprising: feedback control means for controlling the energization of the electric motor based on the proportional gain set by the adjustment means. (2) A scanner capable of reciprocating operation; an electric motor that drives the scanner in forward/reverse rotation; signal generating means that is mechanically coupled to the electric motor and generates electric pulses with a frequency proportional to the rotational speed of the electric motor; speed detection means for detecting the speed of the scanner using electric pulses generated by the signal generating means; position information detection means for detecting position information of the scanner using electric pulses generated by the signal generating means; When the value is large, the scanner's forward drive power and proportional gain of feedback control are set to a large value in response to the position information when the scanner stops during the scanner's backward movement. means; and a proportional ratio set by the adjustment means so that the electric motor is energized in the forward drive direction of the scanner with the forward drive power set by the adjustment means, and the detected speed detected by the speed detection means matches the target value. A scanner control device comprising: feedback control means for controlling energization of an electric motor based on gain.