JPS59152435A - Scanner - Google Patents

Abstract

PURPOSE:To control smoothly acceleration and deceleration by turning off an electric conduction to a DC motor at the time of the acceleration and the deceleration for a constant interval of time at every pulse corresponding to a rotation of the DC motor, and turning it on until the following pulse after the elapse of off-time. CONSTITUTION:In case of the deceleration, an input terminal 9a is switched to an L in order to give damping force, and an input terminal 9b is on-off controlled. That is to say, a constant off-time is set at every pulse of an encoder 3 generated in accordance with a rotation of a DC motor 2, and it is controlled as an on-time until the following pulse. At the beginning of the deceleration, a pulse interval is shorter than the set off-time, therefore, a scanning system 1 is decelerated gradually by weak damping force, and it is decelerated by strong damping force as the pulse interval becomes long. Also, at the beginning of the acceleration, the pulse interval is long, said scanning system is accelerated strongly by strong electricity conductive torque, and when the pulse interval becomes short, the accelerating force becomes weak gradually. In this way, the the acceleration and deceleration are executed smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a scanning device in which a scanning system in a copying machine or the like is reciprocated by a DC motor.

BACKGROUND OF THE INVENTION In recent years, the functions of copying machines have been required to increase in speed, and in particular, the scanning system of a copying machine having a reduction close-up function is required to be even faster than copy paper conveyance speed. For this reason, an on/off control method using a DC motor has been proposed in place of the conventional method of transmitting the driving force of a main motor via a clutch.

Control of a DC motor is to obtain a predetermined speed by controlling the ON time for a certain period of time or a certain number of revolutions. This on/off control is performed by calculations based on the measured speed and numerical values stored in the microcomputer's memory, but during constant speed control, the speed changes during starting, braking, and direction changes. When driving, a large amount of control data must be stored in order to achieve smooth speed changes, and the disadvantage is that the control using that control data becomes extremely complex. Ta. Smooth acceleration/deceleration control is essential in order to minimize impact on the scanning system. This is because the smaller the impact applied to the scanning system, the shorter the preliminary movement distance, the lighter and more compact the scanning system, and the higher the speed.

Purpose/Summary The present invention has been made in view of the above points, and is a scanning method using a DC motor control method that can perform smooth acceleration/deceleration control without requiring a large amount of storage capacity or elaborate control. This is achieved by controlling the power supply to the motor to be turned off for one period of time for each pulse that is generated, and to turn on the power to the motor after the lapse of the off time until the next pulse is generated.

The interval between the pulses is long when the speed of the scanning system is slow;
As the speed of the scanning system increases, the length becomes shorter. Therefore, if we set a constant off time and use the remaining on time, when the speed of the scanning system is slow, the on time will be longer and when the speed is faster, the on time will be shorter. The acceleration decreases as it approaches the speed control speed,
During deceleration, the braking force is small at high speeds, and larger braking force can be applied as the speed decreases.

Embodiment Hereinafter, one embodiment of a scanning device according to the present invention will be described with reference to the accompanying drawings. This embodiment is applied to an electrophotographic copying machine, and in FIG. 1, (1) is a scanning system including an illumination system, (2) is a DC motor, and the scanning system (1) is a ), that is, forward movement in the direction of arrow (A) and backward movement in the opposite direction. (3) is the encoder, and the DC motor (
2) is installed on the rotating shaft and generates pulses proportional to the rotation speed.

(4) is a home switch, which detects that the scanning system (1) is at the home position (scanning start position). When it is detected by this detection signal that the scanning system (1) is not at the home position at the start of scanning, control is performed to return the scanning system (1) to the home position. (5) is a brake switch that detects when the scanning system (1) reaches a predetermined position on the return, and is used as a signal to start braking upon return in the flowchart described later.

Figure 2 shows a switching circuit for controlling the DC motor (2).
t ) to the DC motor (2), and diodes (Dl) to (D4) are connected in parallel with each transistor (Tr, ) to (Tr, ) to form a bypass for the back electromotive voltage. There is.

Input terminal (9a) is forward rotation signal '■', reverse rotation signal 1'LI
+ is input, and is connected to the input side of the AND gate (AND) and the base of the transistor (Tr+), and is connected to the AND gate (AND) via the inverter (1).
It is connected to the input side of AND2) and to the base of the transistors (Tr, ). Another input terminal (91)
) receives the on signal /'HI+ and the off signal "L", and is connected to the input sides of AND, -) (AND, ), and (AND2).

Further, the output side of the AND gate (AND, ) is connected to the base of the transistor (Tr, ), and the output side of the AND gate (AND, ) is connected to the base of the transistor (Tr, ).

Next, the principle of the present invention will be explained using the operation of the circuit shown in FIG. 139 To explain the movement of the scanning system (1),
As shown in FIG. 3(a), a case will be taken as an example in which the forward motion of constant speed control is decelerated, the direction is changed, and the motion is accelerated to continuously shift to forward motion of constant speed control.

In constant speed scan, the input terminal (9a) is LJJ(I+
, the input terminal (9b) is controlled on/off based on the measurement of the parnu from the encoder (2). At this time, when the input terminal (9b) is rL HI+, the transistor (Tr
, ) and (Tr3) are on, and the current from the DC power supply 4) flows in the direction U in FIG. 2, driving the DC motor (2) in the forward direction.

Next, when decelerating in the forward direction, the input terminal (9a) for applying braking force is switched to /7LIT,
The input terminal (9b) is on/off controlled by the control method of the present invention. That is, a constant off time is set for each encoder pulse generated in response to the rotation of the DC motor (2), and the period up to the next encoder pulse is controlled as the on time.

Input terminal (9a) is Jr LI+ and input terminal (91))
In the state of ``L'', the transistor (Tr, ) in Figure 2
Arrow l in the closed loop of only ontransinuta (Tr+)
) direction generates a back electromotive force that brakes the forward rotation.

Hereinafter, braking using this back electromotive force will be referred to as regenerative braking.

On the other hand, the input terminal (9a) or the input terminal (91)
) is in the IIHIIO state, the transistor (Tr+)
and (Tr, ) are turned on, and the direct current of ) of the DC power supply is indicated by the arrow l.
) direction, attempting to rotate the DC motor (2) in the backward direction.

The case where braking is applied by rotating the scanning system (1) in the opposite direction to the moving direction is hereinafter referred to as forced braking.

Returning to FIG. 3(a), at the beginning of deceleration, the interval between encoder pulses is shorter than the set off time, so only regenerative braking is activated. The scanning system (1) is gradually decelerated by the relatively weak braking force of this regenerative brake, and when the encoder pulse interval becomes longer than the off time, the forced brake also works together with the regenerative brake, decelerating with a strong braking force. (See Figure 3 (b) and (c)).

In this way, by applying a weak braking force at the beginning and gradually increasing the braking force, deceleration can be achieved very smoothly.

By the way, in the applicant's previous proposal, as shown by the dotted line in Figure 3, first only regenerative braking (from point 0 to point A in the figure), then only forced braking (from point A to point B in the figure) )
However, with regenerative braking, the braking force becomes weaker as the speed decreases, so it takes longer to decelerate. On the other hand, compared to this, the system of the present invention can perform deceleration in a sufficiently short time.

When the deceleration ends, the scanning system (1) is accelerated in the backward movement direction. The circuit state at this time is exactly the same as the state at the time of deceleration described above, except that the actual moving direction of the scanning system (1) is different. Therefore, when the input terminal (9a) terminal is LL L I+ and the input terminal (9b) is trHn, driving force is forcibly applied, and the input terminal (, 9a) is L''
The state where the input terminal (9b) is "Ln" is a state of inertial movement.

At the beginning of acceleration, the interval between encoder pulses is long, so the ON time of the DC motor (2) is also long, and strong acceleration is caused by the strong torque. , and as the speed approaches the constant speed control speed, the pulse interval becomes shorter and the acceleration force gradually becomes weaker. Therefore, even during acceleration, the first method of controlling the vehicle according to the present invention can perform very smooth acceleration.

As described above, the control system of the present invention can achieve smooth speed change with curvature control in all of deceleration, acceleration, and continuous transition from deceleration to acceleration during direction changes. still,
It is clear that the above explanation can also be applied to acceleration from the scan start position, direction change from backward to forward movement, and deceleration when stopping at the scan start position.

This is a microcomputer for control. The copying machine has various control objects in addition to the scanning system, and these are controlled by a microcomputer (not shown), hereinafter referred to as a mask.

The microcomputer (20) includes a central processing unit (CPU), 1)-F only memory (R
OM), random access memory (RAM), input capacitor
1- (INPUT to Yade Capo 1- (0UTPUT),
Counter (Tf), timer register (Tw) or ff
4, and INPUT receives the control request signal MAG from the mask.

5CAN and BRAKE are input. Signal MAG indicates the selected magnification and sets the scanning speed. Signal 5CAN is 7/I I+ for forward movement.
to instruct return movement. The signal BRAKE is rr 1 while the scanning system (1) turns on the brake switch (5) during backward movement.
rr.

From 0UTPUT, the motor drive signal and forward/reverse signal F are output to the Nuwitching circuit (21) shown in Figure 2.
This controls the DC motor (2).

The CPU has two interrupt terminals, one of which receives an encoder pulse obtained by shaping the output of the encoder (3) with a waveform shaping circuit (22). The other terminal is connected to a timer register (Tw), and a timer value Tll., which will be explained in the flowchart described later, is set in the timer register (Tw). Timer register (T
W) is this timer value Tw and the external reference oscillator (23)
The reference pulse of the counter (Tf) is compared with the time Tf, and if the two match, a CPUK interrupt signal is input.

No. 51bA, B, and C are microcomputer y (20
) is a flowchart explaining the control of FIG. 5A.
is the main routine, and Figure 5B is the timer register ('l
Figure 5C shows the routine of timer interrupt INT-T caused by "w)", and the routine of external interrupt INT-E caused by encoder pulse
Showing Tulsichin.

To explain the main routine in Figure 5A, once the reset is applied to the meter knob, the motor drive signal is set to o'' in step 2.D=Q is the input terminal J terminal in the switching circuit in Figure 2. (9b) corresponds to the state of L″, and 1)=l
corresponds to the H'' state.

Next, in step 2, the scanner waits until a scanning request is received (5CAN=l), then inputs the copy magnification MAG in step 2, and controls the scanning speed corresponding to the copy magnification in step 2. Calculate the reference encoder, - roof/lev spacing Ts. This reference encoder pulse interval Ts is the encoder puff 2 at the time of equal notification set in advance.
It is obtained by multiplying the distance To by the copy/magnification factor.

Next, in step 2, the forward/reverse rotation signal F is set to "B".

F-1 is the input terminal (9a) of the Nuinoting circuit shown in Figure 2.
corresponds to the H'' state, and F20 corresponds to the /rI, II state.

Following this, in step ■, the motor drive signal is set to rr 1
By setting it to u, the scanning system (1) starts forward movement.

In step ■, the counter SYNC is set to 172 to synchronize the encoder pulse with the interrupt /L/-chin.
u, set the processing mode in the interrupt routine to acceleration control mode (MODE=1), and perform the following step ■
Please excuse the interruption. Control of the scanning system from the time of this interrupt is handled by the interrupt routine, and the main routine waits in step [phase] until the scanning request 5CAN becomes uON. During this time, acceleration control and normal constant speed control using the control force ' formula of the present invention are performed. 5CAN=
The time for step 1 is determined by Manuta based on the copy paper size and copy magnification.

When 5CAN = 0, use the nut knob ■ to set the speed mode (MODE = 0) to 7), turn off the motor drive signal at step 0, and reverse the forward/reverse signal at step q♂ (F = 0). )? It is. Temporary speed +ll for processing including Hatake11
The reason for switching to the 11 constant mode is that once interrupt processing is interrupted, synchronization with the encode pulse must be reestablished during the next interrupt processing, which may cause a delay in control.
This is because there are three.

Following step 8, step ■ is the deceleration control mode (M
ODE=2) is set and l-, and deceleration control according to the present invention is performed in the interrupt routine. In the interrupt routine, when further deceleration is completed, the motor is turned on and the speed lj! : I foot mode all modes t. Speed control is not performed in constant speed 1j11 mode, so when scan = 1) is issued (step [phase]), the motor is turned off in step G) and the forward/reverse signal F is switched to forward rotation ('F = 1). , Step @ sets the deceleration control mode (MODE=2), and waits until the mode becomes speed 41 (j constant mode ('MODE, , Q) (step 0).

When the speed measurement mode is set, interrupts are disabled in step [phase], the motor is turned off in step ■, and the nute knob is turned off.
Return to

In this way, the control of the main routine is extremely simple.

FIG. 5B shows the timer interrupt routine INT-T, which is processed by interrupting the main routine every time amplifier of the timer value Tw set by the external interrupt routines IN and TE. Ru.

When a timer interrupt occurs, first, step 2 determines whether the on/off flag is 0NOFF or not. On/off flag 0
NOFF is a flag set in an external interrupt routine, and if 0NOFF=1, the motor drive signal is set to D=Q in step [phase]. In the case of 0NOFF=Q, the motor drive signal is set to D=1 in step [phase].

As mentioned in the principle explanation, constant speed control controls the on time between encoder pulse intervals, and in the control according to the present invention, (H(J) sets a constant off time of the encoder pulse interval. Therefore, in constant speed control, the on/off flux is set to 0NOFF=l, and after the set on-time has elapsed, a timer interrupt causes a step change...?
Turn off the motor.

On the other hand, in the control according to the present invention (the on-off flux is 0N
OFF is set to 20, and after a certain OFF time has elapsed, step 1 is triggered by a timer interrupt. ] Turn on all motors.

Next, using FIG. 5C, the external interrupt routine INT-E is
Explain. This routine is processed by interrupting the main routine every time a pulse is generated from the encoder (3) that detects the rotation i of the motor (2).

When an interrupt is generated in Fig. 5C, the counter (
Copy the value Tf of Tf') to the register (Td) set in the RAM0 sufficient area. Therefore, 6V dinuta (Tc
) indicates the generation time Tc of the current encoder pulse.

Next, in step @, the value of the counter 5YNC is added up, and if it is other than zero, f'lJ is subtracted from the count value in step (@).

This counter 5YNC is connected to encoder pulse and interrupt rule.
This is used to synchronize the pulses, and since two encoder pulses are required to determine the pulse interval of the encoder low, it is set for the purpose of invalidating the calculation result of the pulse interval during that time. In this embodiment, the initial value of the counter 5YNC is set to "2" so as not to ignore even the first pulse.

In step @, the encode pulse interval Ti is determined.

This calculation is obtained by taking the difference between the current encoder pulse generation time Tc and the previous encoder pulse generation time Tp, which has been set for each step. The previous encoder pulse generation time Tp is stored in a register (Tp) set in RAM in the same way as the register (Tc), and the current encoder pulse /l/
y, is updated by copying the occurrence time Tc to the register (T'+3).

In the step [phase] (Φ [phase] of ρ(), a mote “determination” is performed.

In this example, the mode is the 11-leg mode for speed (MODE=
0) Acceleration system? al mol-” (MODE = l
), deceleration; 1ill sub-mode (MODE=2) and constant speed i1r'l sub-1 mode (MODE=3) 4!
11! cheek is set, :X10DE=Ofd: Main routine and step 8 described later, +V
IODE” 1.2 is set in the main routine!z,
MODE=3 is set in step 3, which will be described later.

Speed Z-th] For constant mode (IvIODE=0):,
step, step Q~ (Shio's speedometer;
Return to the main routine immediately.

In the case of constant speed regular motor t' (MODE 23), set whether the counter is SYNC or o'' in step [phase].
Divide the on-time time of the motor that powers the target speed by t1 plus 2 and set it in the temporary storage register (Ton).Step i>7) Set the on-off flag 0NOFF to II.
Step I II), set the motor drive signal to 1"
Make it. Here, the ON time 1 river TOn is the difference between the measured encoder pulse interval Ti and the reference encoder pulse interval Ts corresponding to the target speed during the ON time T:, y■] set corresponding to the target speed. It is obtained by adding the value obtained by multiplying the difference by the coefficient Ki.

It will be done. Different values are used for T typ , Ts , and Ki depending on the copying magnification during forward movement.

The on time obtained in this way is added step by step to the current time Tf9 and is stored in the timer register (T%V).As mentioned above, the timer register ('rW) is set to the current time Tf9. Counter indicating time (Tr)
Since the timer interrupt is generated when the two match, the timer interrupt will be generated exactly at the time TOII after the timer register (TW) has been set to 10 seconds, and the motor is on during this time. .

Next, if acceleration control mode = (MODE = 1), 1
First, in step '6, it is determined whether the synchronization is achieved, and whether it is synchronized or below, that is, whether the target speed has been reached is determined (step Q). If YES, the mode is controlled at constant speed in step C. mode. If No in any of step ■C, set the off time Tc II 01 in the temporary storage register (Ton) as if it is in the middle of rising.
Set l step ■), ON/OFF frac 0NO
Set the FF to 〃o'' and the motor drive number to ``0'' for 7 seconds. (Step @ button).

-1 The value set in the time register (Ton) is added to the timer register (Tw') by the operation in step a. In this case, since it is off time control, Tc for one night after the timer register (T to X) is set.
The interpolator is turned off until hol)1 has elapsed.

In the case of deceleration control mode (1 to 10DE-2), it is first determined in step Q whether synchronization is established, and if synchronization is established, the encoder pulses are suspended for a specified period of time Ti.
has become equal to or greater than the parnu interval Tstop corresponding to the end speed of deceleration control, that is, the speed of the scanning system has become less than the end speed of deceleration control. Speed measurement mode - mode (f
(ODE, Q). If NO in any of the steps, it is assumed that the deceleration is in progress and is temporarily stored in the system (
Step 0 (Ton) is set to the fast off time Tchop2 (Ton), and step 0 (Co) is performed in the same manner as in the acceleration control mode. As a result, the motor is turned off for a period of time Te11OP2 while the timer register (Tw) is set.

According to the above flowchart, the scanning system performs scanning under acceleration control, constant speed control, and deceleration control according to the present invention method, and then returns after receiving full power acceleration and deceleration control according to the present invention method. Stop at home position. In the case of multiple copying, return deceleration and scanning acceleration are performed successively. In either case, acceleration/deceleration control is extremely smooth.

The off time according to the present invention is the time Tcl shown in FIG. 5C.
+ol)l and Tchop2 are shown, but the time Tel+apl corresponds to the change in scanning speed due to the reflection of the copying magnification, and the time Tchop2
A plurality of these are prepared in response to changes in the deceleration start speed due to changes in the scanning distance, and optimal acceleration/deceleration control is performed.

Effects As detailed above, the present invention provides a scanning device in which a scanning system is reciprocated by a DC motor, which includes means for generating pulses in accordance with the rotation of the DC motor, and means for generating pulses in response to the rotation of the DC motor during acceleration or deceleration. It is equipped with a controller Jl that controls the energization to be turned off for a certain period of time each time the pulse is generated, and to be turned on after the lapse of the off time until the next pulse is generated, allowing for very smooth processing. You can easily perform a quick stop.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a scanning device to which the present invention is applied, Fig. 2 is a switching circuit diagram of a DC motor, Fig. 3 (a) is a diagram showing the movement of the scanning system for the purpose of explaining the principle, and Fig. 3 ( B) (C) is a diagram showing encoder pulses and energizing torque corresponding to Figure 3 (A), Figure 4 is a block diagram of the control means, and Figures 5 A, B, and C are flowcharts of the control means. be. l... Scanning system 2... DC motor 3... Encoder applicant Minolta Camera Co., Ltd. Fig. 1 Fig. 2 Fig. 4 720 L
1 Figure 5 A

Claims (1)

[Scope of Claims] 1. A scanning device in which a scanning system is reciprocated by a DC motor, comprising: means for generating pulses in accordance with the rotation of the DC motor; and energization of the DC motor during acceleration or deceleration.
Each time the parnu occurs, it is turned off for a certain period of time, and after the off time has elapsed, the next pa) v7. 1. A scanning device comprising: a control means for controlling the device to turn on when a signal occurs. 2. The scanning device according to claim 1, wherein the off time is varied depending on a constant speed control speed after acceleration and/or a deceleration start speed.