JPH05687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive control method for a scanning drive motor of a copying machine, and more specifically, a main drive system driven by a synchronous motor, The present invention relates to a drive control method for a scanning system drive motor of a copying machine, which is equipped with a scanning system that is mechanically independent from the drive system and is driven by a speed controllable scanning system drive motor.

[Prior art and its problems] In a scanning copying machine with a magnification conversion function,
Photoconductor drive speed (V) and scanning speed to scan the document surface
(v) has the relationship mv=V, where copying magnification (m) is taken.

Conventionally, in this type of scanning copying machine, the drive system including the photoreceptor and copy paper conveyance system and the scanning system are driven by a common drive source, and when switching the copy magnification, a drive switching mechanism such as a clutch is used. In the past, the speed of the scanning system was changed by changing the gears that transmit the driving force, but such mechanical speed switching is not suitable for applications with a large number of copying magnification steps or for changing the copying magnification within a predetermined range. It is difficult to apply this to so-called stepless variable magnification, in which the magnification is continuously changed within the range.

For this reason, conventionally, the photoconductor and the scanning system are driven by separate drive motors, the rotation speed of the photoconductor drive motor is detected by an encoder, and the scanning system drive motor is controlled based on the detected rotation speed. A control method has been proposed. As a result, in principle, it is possible to obtain a scanning speed corresponding to the driving speed of the photoreceptor.

However, according to this control, when a momentary load is applied to the photoreceptor drive motor and its rotational speed changes, the encoder output changes, and the scanning speed changes in response to the change in encoder output. become. On the other hand, even if there is an instantaneous speed fluctuation in the photoreceptor drive motor, the speed of the photoreceptor itself does not change much because the inertia of movement of the photoreceptor is large and there is some margin in drive transmission. Therefore, if there is an instantaneous speed fluctuation in the photoreceptor drive motor, the scanning speed will not correspond to the speed of the photoreceptor, which will adversely affect the image.

On the other hand, it is desirable that the motor that drives the photoreceptor be unaffected by slight load fluctuations or voltage fluctuations so as not to adversely affect the image forming process. In this sense, once a synchronous motor has reached synchronous speed, it will rotate precisely in accordance with the frequency of the AC power supply, as long as the load does not exceed the escape torque.
It is suitable as a motor that drives a drive system that includes a photoreceptor.

However, even when a synchronous motor is used as a motor for driving a drive system including a photoreceptor, instantaneous speed fluctuations as described above may occur. Also, when using a synchronous motor in this way,
If a copying machine is used in areas where the frequency of AC power supplies differs, the driving speed of the photoreceptor will vary depending on the area. Therefore, it is necessary to change the scanning speed accordingly.

[Object of the Invention] The present invention has been made in view of the above points, and is not affected by instantaneous speed fluctuations that occur in the synchronous motor that drives the main drive system, and is not affected by the instantaneous speed fluctuations that occur in the synchronous motor that drives the main drive system. An object of the present invention is to provide a drive control method for a scanning system drive motor of a copying machine that can be used even in areas where the frequency of the copying machine differs.

[Means for Solving the Problems] In order to achieve the above object, a method for controlling the drive of a scanning system drive motor of a copying machine according to the present invention includes a main drive system driven by a synchronous motor, and a main drive system driven by a synchronous motor. In a copying machine equipped with a scanning system that is mechanically independent from the drive system and driven by a speed-controllable scanning system drive motor, detecting the frequency of an AC power supply that supplies power to the synchronous motor; The present invention is characterized in that the speed of the scanning system drive motor is controlled based on the detected frequency of the AC power source.

That is, focusing on the fact that the synchronous motor rotates in accordance with the frequency of the AC power source, data on the frequency of the AC power source is transmitted to the speed control circuit of the scanning drive motor, and the transmitted AC power source is Based on the frequency data, the scanning system of the main drive system driven by the synchronous motor is driven in a predetermined relationship.

[Examples] Examples of the present invention will be described below with reference to the drawings.
FIG. 1 shows an electrophotographic copying machine 1 to which the present invention is applied.
FIG. The main motor M is a synchronous motor, and the scanning system drive motor _M1 is a DC motor whose speed is controlled by a control mechanism to be described later.

A photoreceptor drum 11 that can be rotated counterclockwise is disposed approximately in the center of the main body of the copying machine 10, and around it are a main eraser lamp 12, a sub charger 13, a sub eraser lamp 14, and a main charger. 15, a developing device 16, a transfer charger 17, a copy paper separation charger 18, and a blade type cleaning device 19 are arranged in this order. The photoreceptor drum 11 has a photoreceptor layer provided on its surface, and this photoreceptor is connected to the eraser lamp 1.
2 and 14 and charging chargers 13 and 15, it is uniformly charged and subjected to image exposure from the scanning optical system 20.

The scanning optical system 20 is installed below the document glass so that the document image can be scanned, and is composed of a light source 27, movable mirrors 21, 22, 23, a lens 24, and a mirror 25. The light source 27 and the movable mirror 21 are connected to the circumferential velocity V of the photoreceptor drum 11 (equal magnification,
constant regardless of magnification) versus (V/m) (however,
The movable mirrors 22 and 23 are driven by a DC motor _M1 to scan to the left at a speed of (V/2 m). Note that when changing the copy magnification, the lens 24
moves on the optical axis and the mirror 25 moves,
Although a swinging motion is involved, such a magnification changing device is well known and will not be described in detail.

On the other hand, paper feed units 30 and 32 are installed on the left side of the copying machine body, each having paper feed rollers 31 and 33, and the copy paper conveyance path includes a pair of rollers 34 and 35, a pair of timing rollers 36, and a conveyor belt 37. , a fixing device 38, and a pair of discharge rollers 39.

In the above configuration, the main motor M drives a main drive system including the photoconductor drum 11, transport rollers 34, 35, transport belt 37, fixing device 38, etc., and the scanning optical system 20 has a mechanism different from this main drive system. It is constructed independently of each other and is driven by a speed controllable DC motor _M1 . Since the specific power transmission mechanisms of the main drive system and the scanning optical system are not directly related to the present invention, illustrations and descriptions thereof will be omitted.

The image forming operation of the copying machine 10 is well known and will not be described in detail.

In Fig. 2, 1 is a scanning system including an illumination system;
_M1 is a DC motor (scan motor), and the scanning system 1 is driven reciprocally by this skin motor _M1 , that is, forward movement in the direction of arrow A (hereinafter referred to as scan) and backward movement in the opposite direction (hereinafter referred to as return). ) is possible.

2 is an encoder composed of Hall elements,
It is installed on the rotating shaft of the scan motor _M1 and generates a pulse signal proportional to its rotation speed, and the moving distance of the scanning system 1 can be detected by the number of pulses, and the speed of the scanning system 1 can be detected by the pulse interval.

SW-H is a home switch that detects whether or not the scanning system 1 is at the home position (scan start position). When it is at the home position, it issues an on signal, and otherwise it issues an off signal.
SW-B is a brake switch that detects a reference position for the control described below for the scanning system 1. When the scanning system 1 reaches a predetermined position, it issues an on signal, and otherwise it issues an off signal. emits.

SW-E is an exposure switch, which is used to detect the exposure start position, etc. and perform various controls as described below. It issues an on signal when the scanning system 1 reaches a predetermined position, and otherwise issues an off signal. emanate.

FIG. 3 shows the configuration of a control device for reciprocating the scanning system 1.

3 is a microcomputer that is the central part of the control, and is composed of readable and writable random access memory for storing data for braking control, read-only memory, an 8-bit internal counter, input/output ports, etc. . 4 is a driver and protection circuit that controls the scan motor M 1 using the forward/reverse signal F/R and drive signal D/S from the output ports H ₀ and H ₁ of the microcomputer _{3, and also controls the scan motor M 1 in} the event of a load abnormality. to stop.
A waveform shaping circuit 5 converts the pulse signal of the encoder 2 into a square wave, and the falling (or rising) signal is input to the interrupt terminal (INT) of the microcomputer 3. 6 is a reference oscillation circuit,
A fixed frequency reference pulse for measuring the time interval FG of the encoder pulse signal is sent to the external clock terminal ECK of the microcomputer 3.
In the microcomputer 3, this reference oscillation circuit 6
The pulses from the scan motor M1 are counted by an internal counter, and the rotational speed of the scan motor _M1 , that is, the speed of the scanning system 1, is calculated from the counted value, and the pulse interval time is also measured.

The output signal of the power pulse circuit 7 is an AC power supply AC.
is applied to the microcomputer 3 in order to measure the power supply frequency, and the speed of the scanning system 1 is corrected based on this measurement result. In this power supply pulse circuit ₇ , as shown in _FIG . Diode D ₂₁ on the next terminal,
The anodes of D ₂₂ are connected to the diodes D ₂₁ ,
The cathode of _D22 is connected to the terminal PP of the microcomputer 3 via a resistor _R21 . The AC power supplied to the main motor M via the switching element SSR is passed through the transformer TR ₂₁ to the diode D ₂₁ ,
A signal generated by being double-wave rectified by D ₂₂ , current limited by resistor 21, and clipped by Zener diode ZD ₂₁ is input to microcomputer 3 as a power pulse signal corresponding to the power frequency.

FIG. 5 shows a specific example of the driver and protection circuit 4. In FIG.

In the driver circuit, a DC power supply E is connected to the scan motor _M1 through bridge-connected transistors _Tr1 to _Tr4 to drive the scan motor M1 in both forward and reverse directions, and diodes _D1 to _D4 are connected to the scan motor _M1 in both forward and reverse directions. It is connected in parallel with each of the transistors Tr ₁ to _{Tr 4} to form a bypass for electromotive voltage.

The input terminal 10a is a terminal to which the forward rotation signal "L" and the reverse rotation signal "H" of the scan motor _M1 are inputted from the microcomputer 3, and is connected to the AND gate AND _2.
It is connected to the input terminal of the AND gate AND 1 through the inverter I 1 and connected to the base of the transistor Tr ₃ through the buffer I ₄ , and connected to the input terminal of the AND gate AND ₁ through the inverter I ₁ and to the base of the transistor Tr 3 through the buffer I ₃ . Connected to the base of Tr ₃ .
The other input terminal 10b is a terminal to which an ON signal "H" for energizing the scan motor M ₁ and an OFF signal "L" for not energizing the scan motor M ₁ is inputted from the microcomputer 3. and gate through ₃
Connected to AND ₁ and AND ₂ input terminals. Also, the output terminal of the AND gate AND ₁ is connected to the base of the transistor Tr ₂ , and the output terminal of the AND gate AND ₂
The output terminal of is connected to the base of transistor _Tr4 .

In the protection circuit, the cathode of a diode D5 is connected to the terminal to which the transistors Tr ₁ and Tr ₂ of the scan motor M ₁ are connected, and the diode _{D 6 is} connected to the terminal to which the transistors Tr ₃ and Tr ₄ of the scan motor M ₁ are connected. The cathode of is connected. Diode _D5 ,
The anode of D ₆ connects to transistor Tr ₅ through resistor R ₆
connected to the base of The base of the transistor Tr ₅ is further connected to the + side terminal of the power supply E via resistors R ₅ and R ₆ , the emitter of the transistor Tr ₅ is grounded, and the collector of the transistor Tr ₅ is connected via the resistor R ₇ . Connected to +5V power supply (not shown).
Further, a connection point between resistor _R5 and resistor _R8 is grounded via a constant voltage diode _ZD1 .

CO is a counter circuit, the output terminal of the oscillation circuit PG is connected to the count input terminal CL of this counter circuit CO, the collector of the transistor Tr5 is connected to the reset terminal RS of the counter circuit CO, and the count input terminal _CL of the counter circuit CO is connected to the collector of the transistor Tr5. Terminal CU is connected to set terminal S of flip-flop FF. The counter circuit CO counts pulses from the oscillation circuit PG when the transistor _Tr5 is conductive and the terminal RS is "L", and sets the flip-flop FF when the count value exceeds a set value. Further, the counter circuit CO stops counting pulses from the oscillation circuit PG when the transistor Tr ₅ is non-conductive and the terminal RS becomes "H".

In the above configuration, as will be described later, the flip-flop FF is reset and the output goes to "H".
In the forward rotation mode FOR in which the scan motor _M1 rotates forward when the scanning system performs scanning, the input terminal 10a is "L" and the transistor Tr ₃ is turned on, and the input terminal 10b is "H" and the AND gate is turned on.
AND ₁ becomes "H", transistor Tr ₂ is turned on, current flows in the direction of arrow a, and motor M ₁ rotates forward. In addition, in the reverse mode REV, the input terminal 10a switches to "H" and the transistor Tr ₁
is turned on, and when the input terminal 10b is at "H", the AND gate _AND2 becomes "H" and the transistor _Tr4 is turned on, current flows in the direction of arrow b, and the motor _M1 reverses.

On the other hand, in the brake mode FS, input terminal 10a is set to "L" and input terminal 10b is set to "L" in the reverse rotation state.
to turn on only transistor _Tr3 . In this case, the power to motor _M1 is cut off, but
A back electromotive force is generated in the direction of arrow a, which attempts to reverse the rotation of motor _M1 . This back electromotive voltage flows through the transistor Tr ₃ , the motor M ₁ , and the diode D ₁ to apply a brake against the reverse rotation of the motor M ₁ , that is, a regenerative brake.

In this embodiment, in order to control the copying process, the scanning system 1 first performs a preliminary reciprocating motion SCAN:A, RETURN when copying is started. The reciprocating motion SCAN:B, RETURN during actual copying is an optimal control corrected by the data measured in this preliminary reciprocating motion. Of course, the braking during the second and subsequent copying movements is corrected using the data obtained from the previous copying return.

7 to 17 are flowcharts of the control program executed by the microcomputer 3. FIG. Hereinafter, specific control will be described in detail with reference to this flowchart.

First, the outline of the control will be explained using the main routine shown in FIG. When the power is turned on in the microcomputer 3, the internal parameters are initialized and the lens is returned to its normal position in step S1.Then, the power frequency is determined in step S2 (details will be described later), and the power supply frequency is determined in step S3. Data such as copy magnification m and scan size are input, and then data input is repeated until a scan signal is input.
When the scan signal is input, a determination of "YES" is made in step S4, and a subroutine for returning the scanning system 1 to the home position is executed in step S5.
HOME is processed to ensure that the scanning system 1 is located at the home position (scan start position).

Then in step S6 the subroutine SCAN:
A is processed, scanning system 1 performs a preliminary scan,
Here, data for the next actual copy scan is read. Further, in step S7, the subroutine RETURN is processed, the scanning system 1 is returned to the home position, and data for subsequent return is collected. Next, in step S8, a scan signal is input, and if it is judged as ``YES'', in step S9, the subroutine SCAN:B
is processed, actual copy scanning is performed, and thereafter steps S7, S8, and S9 are repeated depending on the number of copies.

Here, constant speed control of scan motor _M1 will be explained.

Constant speed control is the fall (or rise) of the encoder pulse that corresponds to the rotation speed of the scan motor _M1 .
Then, an external interrupt is applied to the interrupt terminal INT of the microcomputer 3, and according to this external interrupt interval and the time counted by the internal counter driven by the reference oscillation circuit 6, [TON + A (FG - FG ₀ )] is sent. This is done by turning on the MTON scan motor _M1 for the time calculated using the formula (see Figure 6). In addition, TON is the reference time to turn on the scan motor _M1 to keep it at a constant speed, FG is the time interval of encoder pulses measured by the above internal counter, and FG ₀ is the motor rotation speed, gear ratio, copy magnification, and power supply. This is a set value that is set based on the amount of deviation from the frequency reference value. Therefore, A is a coefficient that determines the amount of correction of the motor-on time MTON due to the error between the set value and the actual measurement value. Here, TON is corrected by the value of FG in scan time constant speed control, and the value obtained by further correcting that correction value by A (FG - FG ₀ ) is used as the motor on time MTON.
The motor on time MTON is double corrected to a more appropriate value.

In this embodiment, there are two types of constant speed control: scan time and return end interval. Furthermore, during scanning, the scanning speed differs depending on the copying magnification, so the values of FG ₀ , A, and TON are multiple.

The timer interrupt and FG interrupt in the above constant speed control are scan and return subroutines.
Allowed between FGWAIT and MCOFF. Note that timer interrupts are also permitted at the start of return.

A timer interrupt occurs every time the internal counter overflows due to a pulse input from the reference oscillation circuit 6 to the external clock terminal ECK of the microcomputer 3. The internal counter continues counting from zero again even after overflow. In this embodiment, the internal counter is 8 bits and the frequency of the reference oscillation circuit 6 is 200 KHz, so a timer interrupt occurs every 2 ⁸ =256 clocks (1.28 ms).

This timer interrupt is accepted after the FG interrupt processing described later, and the eighth processing routine (INT/T)
As shown in step S202, it is determined whether the motor-on time MTON has elapsed, and "YES" is selected.
If it is determined, the drive is turned off in step S203.
Output the data and return to the main routine. In addition,
If the motor-on time MTON has not elapsed, a determination of "NO" is made in step S202, and the process immediately returns to the main routine. The above drive OFF data is FG
It is set in the RAM area of the microcomputer 3 together with the drive ON data executed in the interrupt processing routine INT-F before the interrupt is enabled. The ON-OFF data is a combination of the forward/reverse signal F/R and the drive signal D/S. F means forward rotation, R means reverse rotation, D means drive, and S means stop. In other words, ON data during scanning is FD, OFF data is FS,
ON data during constant speed control during return is RD,
OFF data is RS. On the other hand, control data for motor _M1 when constant speed control is not performed is similarly output as a combination of forward/reverse signal F/R and drive signal D/S. For example, the control data for forward braking during return is FD, or the control data for regenerative braking during return is FS.

When the timer mode is "1", that is, from the start of return to the start of regenerative braking, the function
Turn OFF data RS to ON data RD, temporarily stop energizing scan motor _M1 , and reset protection circuit counter circuit CO to prevent count-up.
Energization time at return (maximum protection circuit detection time)
On the other hand, this energization stop time is about several μs, so it has little effect on the return speed.

The FG interrupt processing is generated by the fall (or rise) of an encoder pulse corresponding to the rotation speed of the scan motor _M1 , and mainly calculates the time MTON during which the scan motor _M1 is turned on. That is, the ninth
As shown in the figure, the time FG from the previous FG interrupt is calculated in step S301, the difference ΔFG from the set value FG ₀ is calculated in step S302, and the time FG is calculated in step S303.
It is determined whether or not there is a TON correction request.
The TON correction request is set to "1" from the time when the exposure switch SW-E is turned on until the end of scanning, and if it is "NO", the process moves to step S307.
If “YES”, go to step S304 (ΔFG>0)
Determine whether or not. If "YES", the pulse problem (FG) is larger than the set value (FG ₀ ) and the scan speed of the scanning system 1 is slow, so in step 305 a predetermined value (1 in this example) is set as the reference time TON. Add to. If the above step S304 is "NO", the scan speed is fast, so the step
In S306, a predetermined value is subtracted from the reference time TON.

Next, in step S307, it is determined whether (|ΔFG|≦K). K is a constant that determines the tolerance range of the difference ΔFG between the measured value FG and the set value FG ₀ of the encoder pulse interval, and if (|ΔFG|) exceeds the tolerance range, it is determined as "NO" and the process proceeds to step S308. At step S304, it is determined whether (ΔFG>0) or not. If YES, scan motor _M1 is set to full on at step S309, drive ON data is output at step S311, and the main Return to routine. If step S308 is NO, set to full off in step S312, and step
Output the drive OFF data in S313 and return to the main routine.

On the other hand, if the above (|ΔFG|) is within the allowable range, it is determined as "YES" in the above step S307,
In step S310, the calculation formula [TON+A(FG-
FG ₀ )] to find the motor on time MTON, output drive ON data in step S311, and return to the main routine.

FIG. 10 shows the subroutine HOME. This is a subroutine for returning the scanning system 1 to the home position by reversing the main motor M1 if the scanning system ₁ is not at the home position at the start of scanning.

That is, in step S10, the home switch SW-
It is determined whether H is off or not, and if "NO", the scanning system 1 has returned to the home position, and the process immediately returns to the main routine. If "YES", the scanning system 1 is far from the home position, so first, in step S11, the control data is set to RD, and the motor _M1 is driven in the reverse direction.
After setting constant speed control data FG ₀ , TON, and A in S12 and setting RD and RS as drive ON-OFF data, a subroutine is executed in step S13.
FGWAIT is executed and constant speed control is performed.

Here, after confirming that the scanning system 1 home switch SW-H is turned on in step S14, that is, that the scanning system 1 has returned to the home position, step S15 is performed.
At step S16, the interrupt prohibition routine MCOFF is executed, constant speed control is turned off, a stop timer is set at step S16, and the process moves to stop operation (fixed position control). That is, in step S17, the control data is set to FD to drive the motor _M1 in normal rotation, and in step S18, the end of the stop timer is waited for. The reason why the motor _M1 is rotated forward is to cancel the reverse speed at the time of return.
After the stop timer expires, the control data is set to RS in step S19, and the scan motor _M1 is stopped.
Return to main routine. Subroutine FGWAIT
As shown in Fig. 11, interrupt is enabled for constant speed control, and in step S20 the encoder
Wait for the falling edge of the pulse and proceed to step S21.
Set the TON correction request to "0", enable interrupts in step S22, and return to the main routine.

The subroutine MCOFF is used to terminate constant speed control as shown in Figure 12.
After interrupts are prohibited in step S23, the control data is set as RS to stop the motor _M1 in step S24, and the process returns to the main routine.

FIG. 13 shows the subroutine SCAN:A.
SCAN:A is an execution routine for a preliminary scan performed prior to the actual copying scan SCAN:B, and in this routine the data of the motor-on time MTON used for the subsequent copying scan SCAN:B is set.

First, in step S30, the FD is set in the control data to drive the motor _M1 in normal rotation. This full-power normal rotation drive continues until the first encoder pulse input is received, helping the scanning system 1 to move forward. Then, RD is set as drive ON data and FS is set as drive OFF data in the RAM area of the microcomputer 3. Next, in step S31, initial data is set in the control delay counter TM at the time of return. Next, in step S32, constant speed control data FG ₀ ,
Set TON,A. At the same time, step S33
The correction value of the counter calculated from the scan size at copy scan SCAN:B is set as CT. This is because the preliminary scan SCAN: A is set to the minimum scan size and is usually the actual copy scan size.
This is to correct the counter measurement value at the return after the preliminary scan SCAN:A because it is shorter than SCAN:B and the braking start timing also changes depending on the scan size.

Next, in step S34, the subroutine FGWAIT is
is processed, the encoder pulse is input for the first time, and constant speed control is started. And step
At S35, wait for the exposure switch SW-E to be turned on in the scanning system 1, and when it is confirmed that it is turned on, the counter is set to the preliminary scan size at step S36, and a TON correction request is issued at step S37. 1"
and wait for the reference time TON to converge. Step S38 waits until the counter started when the exposure switch SW-E is turned on counts the number of pulses set for the preliminary scan size, and when the count ends, the subroutine MCOFF is processed in step S39.
Interrupts are disabled and constant speed control ends. This preliminary scan SCAN: Reference time corrected by A
TON is saved to register TONR in step S40, and this data is subsequently used in the copy scan SCAN:B.
It is used for constant speed control until the exposure switch SW-E is turned on.

FIG. 14 shows the subroutine SCAN:B.
SCAN:B is a copy scan execution routine performed after the preliminary scan SCAN:A.

First, at step S50, perform a preliminary scan:
As in step S30 of A, the motor _M1 is driven in the normal rotation and the drive ON-OFF data is set.
At step S51, the control delay counter TM at the time of return is corrected. That is, the difference between the constant speed control distance CT measured at the time of return, which will be explained below, and the constant set value CK is determined, and the difference is added to the data TM set last time (preliminary scan). next,
At step S52, the counter is cleared in order to measure the next return braking timing. At the same time, in step S53, the constant speed control data FG ₀ and A saved in the register at the previous return are restored, and in step S54, the preliminary scan SCAN:
Restore the reference time TON found in A.

Next, in step S55, the subroutine FGWAIT is
is processed and constant speed control is started. Then, in step S56, wait for the exposure switch SW-E to be turned on in the scanning system 1, and when it is confirmed that it is turned on, a counter is set to the actual copy scan size in step S57, and in step S58, the counter is set to the actual copy scan size. Set the TON correction request to "1" and start correction of the reference time TON. In step S59, the counter that starts when the exposure switch SW-E is turned on counts the number of pulses set for the copy scan size.
When the process is finished, the subroutine MCOFF is processed in step S60, interrupts are prohibited, and constant speed control ends.

FIG. 15 shows the subroutine RETUN.

First, in step S70, RD is set in the control data and motor _M1 is driven in reverse at full power.
At step S71, constant speed control data during scanning is saved in a register within the microcomputer 3. At the same time, the power supply frequency check routine CHECK, which will be described later, is processed in step S72, the timer mode is set to "1" in step S73, and only timer interrupts are permitted in step S74, so that the return is not driven at full voltage at regular intervals. It turns off instantly. Then, in step S75, the CPU waits for the brake switch SW-B to be turned on in the scanning system 1. When the brake switch SW-B is turned on, a braking delay counter TM is started in step S76, and its completion is awaited in step S77.
The set value of this counter TM is the value of the initial data set in step S31 if it is a return after a preliminary scan, and is the value corrected in step S51 if it is a return after a subsequent copy scan. When the counter TM ends, the timer mode is reset to "1" in step S78, and the step returns to step S78.
In step S79, FS is set in the control data to apply regenerative braking to the skirmisher motor _M1 , in step S80 a predetermined value TC is set in the counter, and in step S81, the end of the count is awaited. When the count ends, FD is set in the control data in step S82,
Apply forward brake to motor _M1 . With this,
When the rotational speed of the motor _M1 , that is, the return speed of the scanning system 1, is decelerated to a predetermined speed or less, this is detected in step S83, and constant reverse speed control data is set in step S84, and the constant reverse speed is set. Control takes place. That is, in step S85, the control data is set to RD to reverse the motor _M1 , and the drive ON data RD and drive OFF data RS are set, and the subroutine is started in step S86.
Processes FGWAIT and performs constant speed control.

Next, in step S87, a counter is set,
In step S88, the number of encoder pulses until the home switch SW-H is turned on in the scanning system 1 is counted, and the counted number CT is saved in step S89. The count number CT accurately corresponds to the distance traveled by the scanning system 1 during constant speed control, and is used in the calculation at step S51 in the next copy scan in order to determine the braking timing at the next return. Then, in step S90, subroutine MCOFF is processed, interrupts are prohibited, and constant speed control is ended. Thereafter, the home position control, that is, the same control as in steps S16 to S19 of the subroutine HOME is performed, and the scanning system 1 is stopped at the home position.

FIG. 16 shows a routine for checking the power frequency of the main motor M.

In step S100, the number of measurement pulses is set to 5 or 6 in step S101 or S102 depending on the power frequency of 50 Hz or 60 Hz of the AC power source determined at power-on, and the measurement time is set to be the same for correction.
Based on the measurement results at step S103, the step
In S104, the value obtained by subtracting the standard time of 50 ms becomes the current frequency fluctuation amount, and in order to convert this fluctuation amount into a magnification, it is divided by the change step and used as the frequency fluctuation evaluation constant PSFT. For example, if the magnification data is 1/
For 1000 pitches, the change step is standard time 50m.
The result is division by 50 μs, which is 1/1000 of s. This power supply frequency check is performed every time the scanning system 1 returns, and in step S105, PSFT is added to the copying magnification m input in the data input routine to calculate the copying magnification m' corrected by the frequency fluctuation. Steps to change the speed of the next scan.
FG ₀ is recalculated in S106.

FIG. 17 shows a routine for determining the power frequency of the main motor M.

In this routine, it is determined whether the current power frequency of the AC power source AC when the power is turned on is from 60Hz to 50Hz. In step S110, the time for six power pulses is measured, and in step S111, it is determined whether the power frequency is 60 Hz or 50 Hz depending on whether the measured time is shorter than the period of 55 Hz. The power pulse has a period of 6 pulses during double-wave rectification of 50Hz.
60ms, 54.5ms at 55Hz, 50ms at 60Hz
Therefore, if the measurement result is shorter than 54.5ms, 60
It is judged as Hz.

[Effects of the Invention] As explained above, according to the present invention, when the speed fluctuation of the synchronous motor that drives the main drive system is instantaneous due to load fluctuation, the speed of the scanning system drive motor is equal to the speed of the AC power supply. Since it is controlled in response to frequency, it is not affected by this. In addition, the rotational speed of the synchronous motor will differ in areas where the frequency of AC power supply differs, and even in such cases,
The main drive system and the scanning system can be controlled by correlating the drive speeds of the main drive system and the scanning system.

[Brief explanation of the drawing]

The first is a diagram showing the configuration of the copying machine, the second is a perspective view of the scanning system, the third is a block diagram of the control device, and the fourth is a diagram showing the configuration of the copying machine.
The figure is a circuit diagram of the power supply pulse circuit, Figure 5 is a circuit diagram of the driver and protection circuit, Figure 6 is a pulse waveform diagram for explaining constant speed control, and Figures 7 to 17 are flowcharts of the control device. It is. 1...Scanning system, 3...Microcomputer,
4... Driver and protection circuit, 5... Waveform shaping circuit, 6... Reference oscillation circuit, 7... Power supply pulse circuit, 10... Copying machine, 11... Photosensitive drum, M
...Main motor, M ₁ ...Scan motor, AC
……AC source.

Claims (1)

[Claims] 1. A main drive system driven by a synchronous motor;
In a copying machine equipped with a scanning system that is mechanically independent from the main drive system and driven by a speed-controllable scanning system drive motor, the frequency of the AC power supply that supplies power to the synchronous motor is detected. A method for controlling the drive of a scanning system drive motor of a copying machine, characterized in that the speed of the scanning system drive motor is controlled based on the detected frequency of the AC power source.