JPH0377502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reciprocating scanning drive device such as an optical operation system of a copying machine, and more particularly to positioning control of a standby stop position of a scanning system.

Generally, in a reciprocating scanning drive device, after completing one scan, it is necessary to position the scanning system at a predetermined standby stop position, that is, a home position. Therefore, conventional devices are equipped with a home position sensor that detects whether the scanning system has reached a predetermined position near the home position, and control the backward scan when the home position sensor detects the predetermined position during backward scanning. I am now using scanning stop control instead. However, the distance that the scanning system moves from when the backward scanning control is stopped to the scanning stop control mode until the scanning system actually stops depends on factors such as friction in the scanning system, and is therefore affected by ambient temperature, etc. fluctuate. In other words, the actual stop position of the scanning system will vary due to temperature and other factors, and will deviate from the target home position. However, in the case of a copying machine, for example, if the standby stop position or start position of the scanning system changes, the correspondence between the image reading position of the scanning system and the exposure position on the photoreceptor, that is, the position synchronization, will deviate. The image position of the original and the image of the copy are misaligned.

Note that the prior art related to the present invention is disclosed in Japanese Unexamined Patent Publication No. 56
It is disclosed in Japanese Patent Publication No. 125988 and Japanese Patent Publication No. 39-27796. In the former case, the scanner will stop after passing a specific home position, so
The stop position is inaccurate, and the time required from starting the motor until the scanner reaches the reading start position varies.

The first purpose of the present invention is to accurately position the scanning system at the home position regardless of temperature, etc., and the second purpose is to automatically correct the position when the standby stop position shifts. It is an object of the present invention to provide a reciprocating scanning drive device.

In order to achieve the above object, the present invention counts feedback pulses generated as the scanning system moves, detects the moving distance of the scanning system, and controls the movement of the scanning system based on the detected value. In the reciprocating scanning drive device to be controlled, a scanning system position detecting means disposed a predetermined distance away from a target home position of the scanning system on the forward movement side;
The first counting based on the above feedback pulse.
and a second counting means, and the number of feedback pulses corresponding to the distance from the position detecting means to the end position of the forward scan is set as a first predetermined value, and the number of feedback pulses corresponding to the predetermined distance and the first The number of pulses that is the sum of the number of pulses and the predetermined value of 1 is set as a second predetermined value, the second predetermined value is preset in a second counting means, and the second counting means is counted down from the start of forward scanning of the scanning system. Then, the scanning system detection signal from the position detecting means stops the counting of the second counting means and holds the value, and further sets the first counting means to zero.
The up-count is started from , and the drive of the scanning system is controlled so that the forward scan ends when the first counting means reaches the first predetermined value, and after the forward scan ends and before the backward scan starts, The value held by the second counting means is set in the first counting means, the first counting means is counted down from the start of backward scanning, and when the first counting means reaches 0, and control means for controlling the driving force for backward scanning to the scanning system to be cut off.

According to this, when the standby stop position of the scanning system deviates even slightly from the target home position, the second position detection signal is output from the position detection means.
The value of the first counting means changes, and the value set in the first counting means before the start of backward scanning is automatically updated to bring the standby stop position closer to the target position. Even if the position is changed, the position will be automatically corrected before the positional deviation becomes large.

The first and second counting means for counting pulses according to the scanning distance may be counters, microcomputers, or a combination thereof. In one preferred embodiment of the invention, there are two sets of counters, one set for scanning control and the other set for counting the distance between the standby position and the first position. used for This makes the circuit configuration relatively simple.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a drive mechanism of a reciprocating scanning drive device according to an embodiment of the present invention. This will be explained with reference to FIG. 6 is a first mirror, and 7 is a rod-shaped light source. The light source 7 is covered with a light shielding plate 8 so that the light does not directly hit the first mirror 6. The first mirror 6 is supported so as to be movable back and forth in the direction of arrow B. The light source 7 is integrated with the first mirror 6 and moves together with the first mirror 6. 9 is a second mirror, and the first mirror 6 moves back and forth in the same direction as the first mirror 6 (arrow B) at half the speed of the first mirror.
is connected to. First mirror 6 and second mirror 9
is connected to a motor 13 via one wire 12. That is, the wire 12 with one end 12a fixed passes through the mirror pulley 14 coupled to the second mirror 9, passes through the turn pulley 15 and pulley 16, passes through the drive pulley 17 coupled to the motor 13, and passes through the pulley 16 again. , through a turn pulley 18, and is coupled to the first mirror 6 with a wire clamp 19, and through a mirror pulley 14, the other end 12a is fixed. When the motor 13 rotates, the first mirror 6 moves at a predetermined speed,
The second mirror 9 moves at half the speed of the first mirror 6. 20 is a tension roller that applies tension to the wire 12. In this embodiment, a DC servo motor is used as the motor 13. A rotary encoder 21 is coupled to the shaft of the motor 13 to detect the amount of rotation of the motor. A light shielding plate 22 is fixed to the wire 12, and a transmission type photo sensor 23, that is, a position detection means, is used to detect the scanning system within a predetermined range including the home position (see FIG. 3b).
The light shielding plate 22 is arranged at a position to block the light when the light is located at PO0 to PO2).

2a and 2b show electrical circuits for controlling the energization of the scanning mechanism of FIG. 1. FIG. The configuration will be explained with reference to FIGS. 2a and 2b. In this embodiment, a single-chip microcomputer manufactured by Intel Corporation is used as a control means.
It uses 8048 CPU. The analogue servo control system in Fig. 2a includes a forward scanning control system, a backward scanning control system,
It consists of a backward scanning stop control system, a servo amplifier DRV, a rotary encoder 21, etc. The forward scanning control system includes an F/V converter FVC and a reference voltage generator.
The backward scanning control system is composed of RV and error amplifier ER1.
and an error amplifier ER2, and the backward scanning control system includes a photo sensor 23, a sense amplifier SA, and a phase correction circuit PR. SMA is an adder, and the output signals of the forward scan control system, backward scan control system, and backward scan stop control system are applied to the adder SMA via analog switches AS1, AS2, and AS3, respectively, and the output signals of the adder SMA are is applied to the servo amplifier DRV. analog switch
Control input terminals of AS1, AS2 and AS3 are connected to output ports P26, P25 and P24 of the microcomputer CPU, respectively.

Rotary encoder 21 is disk DK and 2
It has two transmission type photo sensors PS1 and PS2. A large number of slits are formed at equal intervals around the disk DK, and photo sensors PS1 and PS2 are arranged to sandwich the slits. When the disk DK rotates, a state in which the slit portion faces the photo sensors PS1 and PS2 and a state in which the non-slit portion of the DK faces the photo sensors PS1 and PS2 repeatedly occur, and the outputs of PS1 and PS2 reflect the amount of rotation of the DK. In other words, a number of pulses are generated depending on the amount of scanning. The disk position where PS1 generates a pulse and the disk position where PS2 generates a pulse are shifted by 1/4 of the slit interval. In other words, the pulse signal ΦA output by PS1
There is a phase lead/lag of 90 degrees between it and the pulse signal ΦB output by PS2. In this example,
The positions of photo sensors PS1 and PS2 are set so that during forward scanning, signal ΦA is in a phase delayed state with respect to ΦB, and during backward scanning, signal ΦB is in a phase delayed state with respect to signal ΦA. . The signal ΦA is connected to the input port T1 of the microcomputer CPU, the input end of the F/V converter FVC, and the second
It is applied to the input terminal R of the phase comparator PC in figure b.
The signal ΦB is applied to the input terminal V of the phase comparator PC.

The digital circuit shown in Figure 2b consists of a phase comparator
PC, AND gate AN1, AN2, AN3, AN
4. Counter CO1, CO2, CO3, CO4, CO
5 and CO6. counter CO1
~CO6 in this example uses SN74193 manufactured by Texas Instruments. counter
CO1 to CO3 are the first counting means, and the counter
CO4 to CO6 are the second counting means. These counters are 4-bit binary up-down counters with preset inputs, as shown in Figure 2b: preset inputs A, B, C and D, count-up input CU, and count-down input CD , load (preset the data at the preset input terminal to the counter) input terminal LD, clear input terminal CLR, data output terminals Qa, Qb, Qc and Qd, carry output terminal CY and borrow output terminal
Has BR. CO1, CO2 and CO3 are 1
Connected as a pair of 12-bit counters, CO
4, CO5 and CO6 are similarly connected as a set of 12-bit counters. CO4, CO5 and
The preset input terminals A to D of CO6 are connected to the output ports P10 to P23 of the microcomputer CPU.
Apply preset data PSD from . Output data from counters CO4, CO5 and CO6 are applied to preset input terminals A to D of counters CO1, CO2 and CO3, respectively. The output data CND from the count data output terminals of counters CO1, CO2 and CO3 is
Applied to A converter DAC and decoder DE. Decoder DE has input data CND of 1000
When this happens, a negative logic pulse signal is output to the output terminal. The borrow output terminal of the counter CO3 is connected to the input port P27 of the microcomputer CPU. The phase comparator PC compares the phases of the signals applied to the input terminals R and V, and if the R signal lags behind the V signal,
A negative logic signal is output to the output terminal U, and if the R signal is ahead of the V signal, a negative logic signal is output to the output terminal D. The signal from U is sent to counter CO1 via AND gates AN1 and AN4.
The signal from D is applied to CU and CD of counter CO4, and the signal from D is applied to CD of counter CO1 and counter CO4 through AND gates AN2 and AN3.
is applied to the CU. ANDGATE AN1 and
Signal EN1 that controls AN2, AND gate AN3
and signal EN2 that controls AN4, counter CO
1. CO2 and CO3 preset control signal LD
1. Preset control signal LD2 for counters CO4, CO5 and CO6, clear signal CR1 for counters CO1, CO2 and CO3, and counter
The clear signal CR2 of CO4, CO5 and CO6 is
Microcomputer CPU output port DB0~
Output from DB5.

FIG. 3a shows the operation of the microcomputer CPU, and FIG. 3b shows the relationship between the scanning position of the scanning system and the pulses from the rotary encoder 21.
The operation of each processing step in FIG. 3a will be described with reference to FIGS. 3a and 3b.

S1 Initialize. That is, each output port is set to the initial state and the scanning system is positioned at the home position PO1.

S2 Wait for start instruction.

S3 Performs various processing to start scanning.
In other words, clear pulse CR is applied to output port DB5.
Outputs 1 and sets the address counters CO1 and CO2.
and CO3, set the signal EN1 to a low level L to disable the operation of the address counter, and set the signal EN2 to a high level H to clear the return point counters CO4, CO5 and CO.
Allow 6 counts and preset data
PSD return point counter CO4, CO5
and CO6, and outputs load pulse LD2 to set the PSD to counters CO4, CO5 and CO
6 and output ports P24, P25.
and outputs L, L, and H to P26, respectively, and turns on the analog switch AS1 to set the forward scanning drive mode. In this example,
Preset data PSD is set to 1010.
Now, a predetermined voltage determined by the voltage of the reference voltage generator RV is generated at the output of the error amplifier ER1, which causes the adder SMA and the servo amplifier to
The motor 13 is energized via the DRV and starts forward scanning. When forward scanning is started, pulses ΦA and ΦB with a period corresponding to the scanning speed are generated at the output end of the rotary encoder 21. Note that in this case, ΦB is ahead of ΦA in phase. Due to this pulse, a voltage corresponding to the rotational speed of the motor 13 is generated at the output terminal of the F/V converter FVC,
The error amplifier ER1 is connected to the motor 1 so that this voltage is equal to the output voltage of the reference voltage generator RV.
Control the rotation speed of 3. Also, in this state, when the servo motor 13 rotates, the phase comparator PC
Since a pulse equal to the number of pulses of ΦA and ΦB is generated at the output terminal D of , the return point counters CO4, CO5 and CO6 count down the pulses.

S4 The signal from the photo sensor 23 is transferred to port T0.
Wait until the scanning system passes through the detection range W of the photo sensor 23 shown in FIG. 3b. Target home position PO1 and scanning system detection range W
The distance from one end PO2 corresponds to 10 pulses of the signal ΦA in this example. Therefore,
When the scanning system starts scanning from the target home position PO1, when the scanning system reaches position PO2, the return point counter CO4,
CO5 and CO6 finish counting down by 10 counts, so their count value is 1000.
become.

S5 Here, signal EN2 is set to low level L to disable counting of return point counters CO4, CO5 and CO6, and signal EN1 is set to high level H to inhibit address counter CO
1. Allow CO2 and CO3 counting.
Now, the count values of counters CO4, CO5 and CO6 are retained, and the count values of counters CO1, CO2
and CO3 start counting up from count 0.

S6 Check whether the scanning system has reached the forward scanning end position PO3. This means that the count values of address counters CO1, CO2 and CO3 are
When the value reaches 1000 (first value), a negative logic pulse signal is output from the address decoder DE, so check this.

S7 Set port P26 to low level L, turn off analog switch AS1, and set forward scanning to stop.

S8 Outputs load pulse LD1 and presets count values of return point counters CO4, CO5 and CO6 in address counters CO1, CO2 and CO3. That is, when the scanning system starts scanning from the target home position, the contents 1000 (second numerical value) of return point counters CO4, CO5, and CO6 are preset to address counters CO1, CO2, and CO3.

S9 Set port P25 to high level H, turn on analog switch AS2, and set backward scan control mode. Here, the D/A converter
The DAC outputs a voltage according to the count values of the address counters CO1, CO2, and CO3 applied to its input, and the error amplifier ER2 outputs a voltage corresponding to the count value of the address counters CO1, CO2, and CO3, and the error amplifier ER2 outputs a voltage corresponding to the count value of the address counters CO1, CO2, and CO3 applied to its input. 13 is driven in reverse (backward scanning drive). When the motor 13 rotates in the backward scanning direction in this state, the signal ΦA generated at this time is in a phase lead state than the signal ΦB, so a negative logic pulse is generated at the output terminal D of the phase comparator PC. address counter CO1,
CO2 and CO3 down count input terminal CD
counters CO1, CO2 and CO
3, counts down from a preset value. In other words, the scanning system is at the forward scanning end position.
Starting from PO3, as the position approaches PO2 side, address counter CO1, CO2
and the CO3 count value becomes smaller. Since the count value is applied to the D/A converter DAC, the output voltage of the DAC decreases as the scanning system progresses, and the backward scanning control system controls the scanning speed to gradually decrease.

S10 address counter CO1, CO2 and CO3
Check the count value of , and determine whether it is the position to end the backward scanning control mode. This is because the signal BR from the borrow output terminal of the address counter CO3 is applied to the input port P27 of the microcomputer CPU, so when this signal becomes low level L, that is, when the signal BR from the borrow output terminal of the address counter CO1, CO2, and CO3 When the count value becomes "0" or less, it is determined that the backward scanning control has ended. Therefore, if the scanning system starts from the target home position PO1 and the address counters CO1, CO2, and CO3 are preset to 1000 at the forward scanning position PO3,
Since the backward scanning mode is ended by counting down to 1000, which is the same as the count during forward scanning, the position of the scanning system at this point is PO2.

S11 Set port P25 to low level L, turn off analog switch AS2, and set to prohibit backward scanning control.

S12 Set port P24 to high level H, turn on analog switch AS3, and set backward scan stop control mode. In this mode, the scanning system is controlled to advance a predetermined distance (10 pulses in this embodiment) in the backward scanning direction while decelerating, and then stop.

S13 Check if the scanning system has stopped. This is determined by checking whether the state of the signal ΦA changes at port T1.

S14 Check whether continuous scanning mode is set, such as in the case of continuous copying, and return to step S2 or step S3 depending on the result.

In the above description, a case has been described in which the scanning system is accurately stopped at the target home position by the process of step S12. However, if the temperature changes, for example, the change in friction will cause the step to change.
The moving distance of the scanning system in the backward scan stop control mode of S12 may be more than or less than 10 pulses. The operation in this case will be explained assuming that the standby stop position of the scanning system is shifted from the target home position PO1 by 5 pulses from PO0. Return point counters CO4, CO5 and CO6
When you set 1010 and start the scanning system, there is a distance of 15 pulses from the starting position to PO2, so when PO2 is reached, the count value of the return point counter becomes 995 (second number), and then The count value is retained. Counting of the address counters CO1, CO2, and CO3 is started from PO2, and when the count value of the address counter reaches 1000 (first value), forward scanning is completed. Here, the return point counter
995 held in CO4, CO5 and CO6
(second value) to address counter CO1, CO2
and CO3, and continue backward scanning control while decelerating the scanning system until the count value of this return point counter becomes 0. In other words, in this case, the distance over which backward scanning control is performed is 995 pulses, which is smaller than the number of pulses (1000) when the standby stop position of the scanning system is the target home position. , the stop position of the scanning system is automatically controlled to move in the forward scanning direction.
This difference in the number of pulses corresponds to the distance difference between the standby stop position of the scanning system and the target stop position, so if the standby stop position deviates from the target home position by the above control, the scanning system will While scanning, the stop position is automatically corrected and controlled to return the standby stop position to the target home position.

In the above embodiment, a counter is used as the counting means, but if a microcomputer is used as the control means, the operation of the counter may be replaced by counting by software of the microcomputer. If the counter operation is performed by a microcomputer, the circuit shown in FIG. 2b is entirely unnecessary.

Further, in the embodiment, a DC servo motor is used as the scanning drive motor, but this may be replaced with a stepping motor or the like. In particular, when a stepping motor is used, it is difficult to determine the stop position, so the present invention is particularly effective.

Further, in the embodiment, the home position is set within the detection range of the position detection means 23, but the home position may be set further in the backward scanning direction than the detection range of the position detection means 23. However, in that case, since the signal from the position detection means 23 cannot be used in the backward scanning stop control mode, it is necessary to make a change such as performing backward scanning stop control using a signal output from the rotary encoder 21, for example.

As described above, according to the present invention, if the standby stop position shifts even slightly due to temperature changes, the shift is automatically corrected during the next scan, so the standby stop position is always maintained without any special adjustment. Can be maintained at home position. In particular, in the case of high-speed reciprocating scanning drive, it is not possible to take much time to adjust the standby stop position between the end of the backward scan and the start of the next forward scan, but in the present invention, Since the position is automatically adjusted while scanning, high-speed scanning driving can be performed without any time loss.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing the scanning system of a copying machine according to an embodiment, FIGS. 2a and 2b are block diagrams showing the configuration of the electric circuit of the apparatus shown in FIG. 1, and FIG. 3b is a plan view showing the relationship between the position of the scanning system and the number of pulses output by the rotary encoder 21. FIG. 6: first mirror, 7: illumination light, 9: second mirror, 12: wire, 13: motor, 14, 15,
16, 17, 18: pulley, 21: rotary encoder, 22: light shielding plate, 23: photo sensor (position detection means), CPU: microcomputer (control means), ER1, ER2: error amplifier,
DRV: Servo amplifier, SMA: Adder, AS1,
AS2, AS3: analog switch, PC: phase comparator, CO1, CO2, CO3: counter (first counting means), CO4, CO5, CO6: counter (second counting means).

Claims (1)

[Claims] 1. A reciprocating scanning drive device that counts feedback pulses generated in response to the movement of a scanning system, detects the moving distance of the scanning system, and controls the movement of the scanning system based on the detected value. , a scanning system position detection means disposed a predetermined distance away from the target home position of the scanning system on the forward movement side; first and second counting means for counting based on the feedback pulse; The number of feedback pulses corresponding to the distance from the detection means to the forward scanning end position is a first predetermined value, and the number of pulses is the sum of the number of feedback pulses corresponding to the predetermined distance and the first predetermined value. is a second predetermined value, the second predetermined value is preset in a second counting means, the second counting means is counted down from the start of forward scanning of the scanning system, and the scanning system from the position detecting means is The detection signal stops the second counting means and holds the value, and further causes the first counting means to start counting up from 0, and the first counting means reaches the first predetermined value. controlling the drive of the scanning system so that the forward scan is completed, and setting the value held by the second counting means to the first counting means after the forward scan ends and before starting the backward scan; a control means for counting down the first counting means from the start of backward scanning, and controlling the driving force for backward scanning to the scanning system to be cut off when the first counting means reaches 0; Scan drive.