JPH02232643A - Method for controlling scanner optical system of copying machine - Google Patents

Abstract

PURPOSE:To make an overrun quantity constant regardless of variance in operation characteristics of each copying machine and to stop the scanner optical system at a constant position by controlling a scanner motor according to data stored in a nonvolatile RAM when a home position sensor detects the scanner optical system. CONSTITUTION:A control part 20 is provided with the nonvolatile RAM 30, which is stored with data regarding the best manipulated variable of a scanner motor 14 for making the overrun quantity of the scanner optical system constant after the home position sensor 16 detects the optical system according to the difference in operation characteristics due to variance in the mechanical load of each copying machine during the return operation of the scanner optical system. Then when the home position sensor 16 detects the scanner optical system, the scanner motor is controlled with the data regarding the best manipulated variable stored in the nonvolatile RAM. Consequently, even if a reference position passing speed is different, the variance of the overrun quantity and stop position of the scanner optical system is reduced to enable stable copying operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanner optical system control method for a copying machine with a fixed document table. [L11 The general configuration of the optical system of this type of copying machine is outlined in Section 8.
It is shown in the figure. An exposure device including a scanner optical system 2 is provided below a contact glass 1 on which 11 originals (not shown) are placed. Due to this. The reflected light from the yX draft forms an image on a drum-shaped photoreceptor 3. This scanner optical system 2 includes a first scanner 7 comprising an illumination light source 4, a reflector 5, a first mirror 6, etc., and a second scanner 7 comprising a second and third mirror 8.9.
The scanner 10, an imaging lens 11 fixed to the main body of the apparatus, a fourth mirror 12, etc. constitute an aperture system. 13 is dustproof glass. The first scanner 7 and the second scanner 0 have a wire port-1 drive system configuration using the movable pulley principle as shown in FIG. 9 so that the length of the optical path reflected from the document does not change during scanning. 2:1
It is driven forward and backward by the DC motor 4 and the scanner wire 5 at a speed ratio of (The configuration of the drive system itself is well known, so a detailed explanation will be omitted). A scanner home position sensor (hereinafter referred to as HP sensor) 16 having a reflective photointerlag configuration is provided as a reference position detection means for the scanner optical system 2. An E-P shielding plate 17 is provided which can sometimes shield the sensor section of the HP sensor 6. With this configuration, the scanner optical system can be changed from the HP state shown by the solid line in FIG. The system 2 is driven rightward to expose and scan the document surface.The positions of the first and second scanners 7 and 10 shown by imaginary lines in the 8th UA indicate the maximum movement position of the reciprocating operation.The exposure scan is completed. The scanner optical system 2 moves back toward the home position again. In this case, when the scanner optical system 2 moves backward, it is generally driven at a higher speed than when moving forward, and when it approaches the home position HP, it performs deceleration control. Then, when the HP shielding plate 17 crosses the HP sensor 16, the motor 14 is
By changing the direction of rotation from reverse (scanner backward movement direction) to normal rotation (scanner forward movement direction), the overrun position is returned to the home position HP. The stop control to the home position HP will be explained in detail.First, considering the operation of the scanner optical system 2 for one cycle, the 10th
It will be shown in the ward. In FIG. 10, the horizontal axis represents time, and the vertical axis represents rotation WI of DC motor l4. (or the speed of the first scanner 7), and the actual rotation speed of the DC motor l4 (or the scanner speed) is as shown by the solid line with respect to the target value shown by the broken line. , home position}IP will be explained with reference to FIG. It shows a state in which the rotational speed (scanner speed) of the DC motor 14 varies when the rotation speed is reached, and the operating characteristic A' shown by the solid line is as per the target value, and the operating characteristic B' shown by the dashed dot line is lower than the target value. The operating characteristic C' shown by the two-point observation line is higher than the target value.In the conventional system, the rotation direction of the DC motor 14 changes from counterclockwise CCW to clockwise from the time the HP sensor 16 detects the first scanner 7. Until a change to CW is detected, a constant amount of operation (a constant PW) is applied to the forward movement side of the DC motor 14.
M (ON time of pulse width variation m>) is given. As a result, the overrun measure and stop position from the HP sensor 16 (that is, the home position HP) of the first scanner 7 is determined by the overrun amount in the case of operation characteristic B', which is the integral value of the area SL shown with diagonal lines. is shown by
The stopping position is indicated by the difference SL-S between the integral values of the areas SL and S2. In the case of the operating characteristics A' and C' of S, the overrun and stop position will be similar to this. Therefore, according to the conventional method, as is clear from the operating characteristics A', B', and C' in FIG.
The rotation speed of the DC motor 14 when passing through the P sensor 16 (
The overrun amount and stop position vary depending on the scanner speed. This variation causes the following errors. First, when the overrun level is large, the problem arises that the scanner optical system 2 (especially the first scanner 7) collides with other members. In addition, if the first scanner 7 stops on the forward movement side than the HP sensor 16 in a state where Si-S2<O, the speed will increase by the time the scanner optical system 2 reaches the leading edge of the Wi image of the document. The image is not stabilized and appears as a blurred image on the copy. In addition, -ffi, the copy operation is sequence controlled based on the point in time when the scanner optical system 2 reaches the leading edge of the image, and whether or not the scanner optical system 2 has reached the leading edge of the image is determined by using the HP sensor l6. This is done by counting the number of encoder pulses after they come off. As a result, as described above, if the scanner optical system 2 is already on the forward side than the HP sensor 16 when it starts, an error will occur in the counted value and the copy sequence will be disrupted. This causes inconveniences such as the leading edge of the image and the leading edge of the transfer paper not matching. As a means to solve this inconvenience, for example, as disclosed in Japanese Patent Application Laid-Open No. 63-10145, a non-volatile R
There is a method to store it in AM. However, simply changing the braking start time requires an accurate stopping position.
Within 2mm from the target stop position》This is insufficient to control the stop vI to the home position. It's ゛ yo ゛
In view of the above-mentioned circumstances of the conventionally used and proposed stop control method of the scanner optical system of a copying machine to a stop position during the backward movement, the present invention addresses the dispersion of the mechanical load of the copying machine WIW. An object of the present invention is to provide a method for controlling a scanner optical system of a copying machine, which can reduce the amount of overrun of the scanner optical system and variations in the stop position even if the reference position passing speed differs, and can perform stable copying operations. Suppose that In order to solve the above-mentioned problem, the method for controlling the scanner optical system w1 of the present invention in ゜T. In response to differences in operating characteristics caused by variations in target load, data regarding the optimal operation of the scanner motor is collected so that the amount of overrun of the scanner optical system after the scanner optical system is detected by the home position sensor is constant. The above non-volatile RA for each copying machine
When the home position sensor detects the scanner optical system during the backward movement of the scanner optical system, the above non-volatile RAM
The scanner motor is characterized by being controlled by data related to the optimum operation amount stored in the scanner. 1 As mentioned above, depending on the differences in the operating characteristics of each copying machine due to variations in the mechanical load of each copying machine, the overload of the scanner optical system after the scanner optical system is detected by the home position sensor. Data regarding the optimum operating amount of the scanner motor to keep the run amount constant is stored in a non-volatile RAM for each copying machine, and when the home position sensor detects the scanner optical system when the scanner optical system moves back and forth, By controlling the scanner motor using the above data stored in the non-volatile RAM, it is possible to keep the amount of overrun constant and stop the scanner optical system at a fixed position, regardless of variations in operating characteristics between copiers. ．． Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. 1 to 7 are diagrams for explaining an embodiment of the present invention, and the same parts as those shown in FIGS. 8 to 10 are indicated by the same reference numerals. FIG. 4 is a diagram showing the configuration of the control circuit of the scanner optical system 2 according to the present invention. A microcomputer 20 is provided as a control means. This microcomputer 2
0 is based on, for example, a μPD7811G, and connected to this microcomputer 20 are a non-volatile RAM 30 that can write data on the amount of operation applied to the DC motor 14 when the scanner is stopped, and a programmable interval timer 21 such as a μPD8253C as a measuring means. It has been done. Further, the conveyance DC motor 14 of the scanner optical system 2 is connected to the microcomputer 20.
The transistors are connected to each other through driving transistors Trl to Tr4 and their driving is controlled. ! I, transistor TrI,
When Tr3 is on and transistors Tr2 and Tr4 are off, a clockwise (CW) rotating current is supplied to the DC motor 14, and when transistors Tr2 and Tr4 are on and transistors TrI and Tr3 are off, DC is supplied. The motor 14 is supplied with a current that rotates counterclockwise (CCW). Here, the scanner optical system 2 is set to move forward when the DC motor 14 rotates clockwise CW, and to move backward when the DC motor 14 rotates counterclockwise CCW. Further, a rotary encoder 22 as a pulse generating means is directly connected to this DC motor l4. Here, the encoder 22 generates two pulse signals with different phases depending on the amount and direction of rotation of the DC motor 14. One is the A-phase encoder pulse ENCA, and the other is the B-phase encoder pulse ENCA.
This is the 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 changes the pulse interval of the physiognomic encoder pulse ENCA to the internal counter φ]. 2 (oscillation frequency Xi/12 of the oscillator 24 of the microcomputer 20). In addition, the input signal to this counter input terminal C[ is an interrupt input, and encoder interval measurement data (TIM
ER/EVENT C O U N T E RCA
PURE REGISTER (ECPT) value), calculate the rotation speed (scanner speed) of the DC motor 14 based on this data, calculate the error from the target rotation speed (target speed), and calculate the motor speed using proportional/integral control calculations. Calculation and output of control amount (ON time of pulse width modulation (PWM) control) (loading data to programmable interval timer 21)
Do this. Further, the encoder pulses ENCA and ENCB are input to the input terminal PC7 of the microcomputer 20 via the buffers 23 and 25 and the flip-flop 26, and are used for phase difference detection to determine the direction of rotation of the DC motor 14. Further, an oscillator 27 is connected to the timer 21 to obtain a clock signal. Thus, the DC motor 14 is controlled by PWM @ control. R, the data of the PWM @ period is loaded into the counter O of the timer 21, and the PWM @ period data is loaded from the output OUTO of the counter O.
A square wave with WM period is output. This signal is counter 1
This is the gate input. This counter 1 has PWM
The ON time data of the signal is loaded, and a one-shot output synchronized with the PWMm period is output from OUTL, and the gate circuit 2g. The transistor Tr3 or Tr4 is ON/OFF controlled via the transistor 2g. No. 51A shows a waveform example of such PWM control. This figure shows that while the ON time jump toM is variable, the PWM period (=S.N+7opp) is constant. Here, counter O is set to mode 3: square wave rate generator, and counter 1 is set to mode 1: 1-bit programmable one-way rate generator.Since the PWM period t is constant, counter = 0. You only need to load the count once. And PWM t. Load the count number of counter 0 every time N time is changed. Next, the contents of mode 3 and mode 1 of the programmable interval timer 21 will be explained. Figure 6 shows mode 3 (
The timing chart of the square wave rate generator is shown below. In this case, it operates as an n-divided counter for input signals and γ signals. Note that the duty ratio when the count number is an even number is 1/2, and the duty ratio when the count number is an odd number is (n - 1) / 2 n. For example, when the number of counters is n=5, the duty ratio is 2/5.
(active low). When this mode is selected using the control word, OUTO becomes 1, GATEL is set to 1, and the count number is loaded.6 As a result, counting is started. When the count number is even, the first half of the count is OUTO=l. f wheat and a half 1
/2 becomes OUTO=0. When the count number is odd, the first half of the count (nmo 1)/2 is OUTO = 1. Latter half(
n-1)/2 becomes OUTO=O, GA. TEI==
If it is set to 0, OUTO becomes 1 and the count stops in synchronization with the falling edge. After that, when GATE1 becomes 1, counting is restarted from the initial value. If a count number is loaded during counting, a new count will start from the next cycle. If the count number is even, the counter is decremented by 2, and if it is odd, the counter is decremented by 2.
When UTO=1, it is decremented by 1 in the first clock, and it is decremented by 2 from the second clock onward. Figure 7 shows a timing chart for mode 1 (programmable one-shot).This outputs a one-shot pulse (active low) of a specified length.Mode 1 is selected using the control word. Then, OUTO = 1, and after loading the count number, it is triggered by the rising edge of GATE 1 and starts counting.During counting, OUTO = 0, and when counting is finished, OUTO = 1 again.In other words, the pulse width is It is an active low one-shot output corresponding to the number.If a trigger is applied during counting (G
When ATE l is changed from 0 to 1), counting starts again from the initial value. Note that even if you load a count number while counting, it will not affect the running count, but if you apply a trigger, it will start counting with a new count number. In this embodiment, data on the amount of operation applied to the DC motor 14 during stop control of the scanner optical system 2 is stored in the non-volatile RAM 30.
This data can be used to variably control the operating position on the reciprocating side. FIG. 2 shows waveforms of various parts during stop control of the scanner optical system 2 at the home position HP and a timing chart of CI interrupt processing, and FIG. 3 shows a flowchart of C [interrupt processing]. First, every time the A-phase encoder pulse ENCA falls, CIF+ processing is performed. In such interrupt processing, first, it is determined whether the current state of the scanner optical system 2 is forward or backward movement, and if it is forward movement, forward movement processing is performed. The flow of forward processing is the same as before, so it will be omitted. On the other hand, if it is a return movement, the HP sensor 16 detects the first scanner 7 (HP shielding plate 17) (H level) or not (L level). vq
Since the HP sensor 16 is at the I-level and is not detecting the first scanner 7 in the steps of (1) to (3), the scanner optical system 2 (first scanner 7) is adjusted so that the scanner speed corresponds to the current scanner position. ), perform proportional/integral control. When the HP sensor 16 detects the first scanner 7 and reaches the f{ level. Enter stop control for home position HP. In this process, first, the flag ST
Determine whether P is set to 1. This flag STP is used to determine the operation amount only once when the output of the HP sensor 16 changes from L level to H level, and initially flag STP is set to 0. Here, when the output of the HP sensor 16 changes from L level to H level, data on the amount of operation applied to the DC motor 14 is read from the nonvolatile RAM 30 and PWM output is performed. Then, set the flag STP to 1. This kind of processing is the processing by CI interrupt ■. When the flag STP is set to 1, the input terminal PC7 of the microcomputer 20 is set to 1.
Check whether the motor rotation direction has changed from the backward direction CCW to the forward direction CW from the input to v4@shi. Until the rotation direction changes, do nothing even if there is an interrupt like ■■ (
That is, return without changing the PWM output value), and when the rotation direction changes as in CI'Ipi, turn off the DC motor l4, mask the CI interrupt, and return. FIG. 1 shows the state of stop @ control to the home position HP according to the method of this embodiment in correspondence with FIG. 11. That is, the operating characteristic A indicated by the solid line is when the rotation speed of the DC motor 14 is as per the target value a, the operating characteristic B indicated by one point JIIAI is lower than the target value, and the operating characteristic indicated by the two-dot chain line is higher than the target value. It is. If the copying machine exhibits a characteristic like operating characteristic B due to variation in the el% mechanical load of each copying device, the data of the operation violet written to the non-volatile RAM 30 should be made smaller than when it exhibits a characteristic like operating characteristic A. If it exhibits a characteristic like operating characteristic C, it can be increased. In either case, by actually operating the scanner optical system 2, confirming the stop position, and changing the operation amount data accordingly, the optimum operation amount can be easily determined. Confirm the stop position and write the operation amount to the non-volatile RAM 30 using an appropriate measuring device and non-volatile RA.
This may be done manually by the operator using a writing device to M, or when the scanner optical system 2 reaches the home position in CIII1 and the HP sensor moves to the first. There is also a method of measuring the deviation by counting the number of encoder pulses output from when the scanner 7 is detected until the i-motor 14 stops, and writing the operation determined based on this to non-volatile RAM. ．． In addition, if you regularly change the manipulated variable data described above,
I! due to changes over time etc. It is possible to prevent variations in the stopping position due to changes in the load. As mentioned above, the amount of operation to the motor is not fixed at a constant value when controlling the stop to the reference position by the reverse wJ operation of the scanner optical system, but is made variable according to the variation in the mechanical load of each copying device. It is possible to stabilize the amount of overrun of the scanner optical system and suppress variations in the stopping position.
It is possible to perform a good copy operation.

[Brief explanation of the drawing]

Figure 1 shows the fruits of this invention! 1. Curve diagrams showing various stop $i1 control states of the scanner optical system in the above embodiment. Fig. 2 is a timing chart of waveforms of various parts and CI interrupt processing during stop control of the scanner optical system of the above embodiment. Fig. 3 is a flowchart of the CI interrupt processing, FIG. 4 is a circuit diagram showing the implementation of the control circuit of the scanner optical system, FIG. 5 is a curve diagram showing an example of the waveform of the pulse width modulation control, and FIG. A timing chart of an example of the waveform, Figure 7 shows the - of the waveform of other modes.
FIG. 8 is a cross-sectional view showing the configuration of a copying machine with a fixed document table to which the present invention is applied, FIG. 9 is a perspective view showing its drive system, and FIG. 10 is an example timing chart of its scanner optical system. Figure 11 is a speed diagram of one cycle of operation near the stop position of a conventional scanner optical system. 2...Scanner optical system, 3...Photoconductor, 7.10 Scanner, 14...Scanner motor, 16...Home motion sensor, 20...Microcomputer, 30...Nonvolatile RAM Brush 3 Line diagram Figure OU llX&) α4) O dispute) Figure Figure Figure 10 Figure 11 Figure HP sensor

Claims (1)

[Claims] An exposure optical system including a scanner optical system capable of reciprocating motion;
An optical device for a copying machine comprising a scanner motor for transporting the scanner optical system, a control section for controlling the scanner motor, and a home position sensor disposed corresponding to a stop position of the scanner optical system. In the stop control method of the scanner optical system to the stop position, the control unit includes a non-volatile RAM, and the operating characteristics of the scanner optical system due to variations in the mechanical load of each copying machine during the backward movement of the scanner optical system are controlled. According to the difference between If the home position sensor detects the scanner optical system when the scanner optical system moves back and forth, the above non-volatile RAM
A control method characterized in that a scanner motor is controlled using data regarding an optimum operation amount stored in a scanner motor.