JPH02155495A - drive device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a WiA service device using a stepping motor.

[Prior Art] Stepping motors have been widely used in precision equipment and the like because of their characteristics, such as the relatively easy control of rotation speed and rotation angle.

In particular, modern precision equipment such as copying machines and printers, etc.
A stepping motor is widely used as a drive device for equipment, and is often used as a scanning drive source for an optical scanning system in copying machines. In a copying machine equipped with a variable magnification function, the scanning speed of the optical scanning system is varied (constant speed during scanning) in accordance with a set copying magnification to change the magnification of the optical image.

Next, a conventional stepping motor start-up control operation will be explained with reference to FIG.

FIG. 9 is a diagram illustrating a conventional stepping motor start-up control operation, in which the vertical axis represents drive frequency (f) and the horizontal axis represents time (1).

In this figure, fo indicates the initial setting frequency, f indicates the target frequency at the same magnification, and f2 indicates the target frequency at the time of setting the reduction magnification.

In the conventional slow-up (startup process to the target frequency), control is first started from the initial setting frequency f0, and then at time t1.
The target frequency f is reached at . Also, when slowing up to the target frequency f2, which is higher than the target frequency f1, the acceleration is the same as that of the slowing up to the target frequency f. It accelerates and reaches the target frequency f2 at time t2.

In this way, in the conventional slow-up, the target speed is increased while following the same slow-up curve regardless of the final constant speed.

[Problem to be solved by the invention]

Therefore, at the start of slow-up (time t shown in Figure 9)
o) and when the slow-up is completed (time 1 or time t2 shown in FIG. 9), vibrations occur in the optical scanning system. Then, the vibration that occurred at time 〇 and time 1. If the phases of the vibrations generated elsewhere cancel each other out, the generated vibrations will attenuate, but if the phases add to each other, the vibrations will be large and the vibration time will be long. I will do it. Therefore, if this vibration continues up to the image leading position that is preset in the document scanning unit, a problem occurs in which the leading edge of the copied image becomes blurred.

In order to prevent such a problem, it is possible to set the run-up distance of the document scanning unit with a sufficient margin, but this increases the size of the apparatus and slows down the copying speed.

Furthermore, if an attempt is made to improve the above-mentioned problems using a mechanical mechanism, greater precision is required for the optical scanning unit and its drive mechanism, which leads to the problem of increasing the cost of the apparatus.

This invention was made to solve the above problems, and by varying the slow-up completion time according to the target speed, the vibration of the driven medium driven by the driving means can be reduced using an inexpensive mechanical mechanism. The objective is to obtain a drive device that can accurately suppress the

[Means to solve the problem]

The drive device according to the present invention includes a data memory that separately stores time data for starting a stepping motor to a plurality of target speeds for each target speed, and a data memory that stores time data for starting a stepping motor to a plurality of target speeds. A slow-up selection means is provided for selecting time data and setting it individually in the drive control circuit.

(Function) In this invention, when a target speed for the stepping motor is commanded, the slow-up selection means selects one piece of time data from the data memory corresponding to each set target speed, and Set the raising time,
Speed control of the stepping motor is started, and vibrations to the driven medium driven by the stepping motor are suppressed when the start-up time has elapsed.

〔Example〕

FIG. 1 is a control block diagram illustrating the configuration of a driving device according to an embodiment of the present invention. Reference numeral 1 is a stepping motor that moves, for example, an optical scanning unit of a copying machine, which will be described later, at a speed corresponding to a set magnification. Move back and forth. A motor driver 2 outputs drive pulses to the stepping motor 1 in accordance with drive commands output from the control circuit 3.

The control circuit 3 includes CPUs 3a and R that have a built-in timer circuit.
It is composed of an OM 3b, a RAM 3c, etc., and controls the motor driver 2 according to a control procedure (including each step of a flowchart described later) stored in the ROM 3b. The control circuit 3 also serves as a slow-up selection means of the present invention, and when a target speed for the stepping motor 1 is commanded, one piece of time data is sent from the ROM 3b, which also serves as a data memory, corresponding to each set target speed. , sets a start-up time in the drive control circuit (motor driver 2), starts speed control of the stepping motor 1, and selects a driven medium, such as an optical scanning unit, driven by the stepping motor 1 when the start-up time has elapsed. to suppress vibration.

The operation shown in FIG. 1 will be described below with reference to FIG. 2.

FIG. 2 is a flowchart illustrating an example of a drive control procedure for the stepping motor 1 according to the present invention. In addition,
(1) to (16) indicate each step.

In addition, fs in the figure indicates the drive frequency at the time of starting the stepping motor, fe is the target drive frequency (determined by the control system, and is a fixed value after determination), T
rise, 5etvalue, and Tsume are variables, and storage areas are secured on the RAM 3c shown in FIG. 1. Furthermore, the acceleration characteristics of the stepping motor 1 used in this embodiment are determined by experiment, and the time tp (50 m5ec in this embodiment) and the time tT (70 m5ec in this embodiment) are determined by the ROM 3.
Assume that it is stored in b.

Note that time 1p indicates the time from when the stepping motor 1 is started to the first trough (details will be described later), and time tT indicates the time from time 1p to the next trough.

First, set the variable Trise to 9, for example, 50 m5ec (1). Next, calculate the slope k of the slow-up based on the following equation (1) (2) Next, determine whether the value of the slope k calculated in step (2) is smaller than a predetermined value 3) NO In the case of , that is, if it is necessary to increase the generated torque of the stepping motor 1, in order to avoid this and adjust the timing at the next valley, in step (16), the variable Trise is further set to 70 m5ec, and the step ( Return to 2).

On the other hand, if the judgment in step (3) is YES, the reciprocal number (period) of the drive frequency fs is calculated and the variable 5etval is calculated.
ue (variable 5atvalue saves the period T of the current driving frequency) (4).

Next, set the value of the variable 5etvalue (to save time from the time when the stepping motor 1 is started) to the variable Tsume (5), and further set the value of the variable 5etvalue to the internal timer of the CPU 3a (6).

Next, wait for the internal timer to complete counting the set value (7), and when the internal timer completes, switch the excitation pattern of the stepping motor 1 (8).
Therefore, the stepping motor 1 rotates for one pulse.

Next, it is determined whether the constant speed (target drive frequency fe) has been reached, that is, based on the flag C0N5TF.9
) If YES (7), return to step (6). Note that this flag C0N5TF is set in step (
15) is executed.

On the other hand, if the determination in step (9) is NO, the next drive frequency f is calculated based on the following equation (2) (10
).

f = k
) Next, it is determined whether the next driving frequency f is larger than the target driving frequency fe (11), and if No, the reciprocal number (next period) of the next driving frequency f is calculated, and the variable 5etva is
12). Then, the variable Tsume
Store the value obtained by adding the value of the variable 5etvalue and the immediately preceding value of the variable Tsume (13), and return to step (6).

On the other hand, if the determination in step (11) is YES, it is determined that the slow-up of the stepping motor 1 has been completed;
After that, in order to drive the stepping motor 1 at the target drive frequency fe, calculate the reciprocal of the target drive frequency fe,
Set the variable 5etvalue (14). Next item,
Set the flag C0N5TF to "1" (15) and return to step (6).

As a result, as shown in FIG. 3, each target drive frequency f
For el to fes, a predetermined time 50 m5ec is the valley of the acceleration characteristics of the optical scanning unit 14, which will be described later, driven by the stepping motor 1.

120 (50+70) msec, 190 (50
+70+70) Complete slow-up to constant speed at m5ec.

FIG. 3 is a diagram explaining the slow-up characteristics of the stepping motor 1 shown in FIG. 2, and the vertical axis is the frequency (f).
, and the horizontal axis indicates time (1).

In this figure, f JMw f e6 indicates each target drive frequency.

Next, a case will be described in which the drive device shown in FIG. 1 is applied to a copying machine.

FIG. 4 is a plan view illustrating the drive mechanism of the optical scanning system of a copying machine to which the present invention is applied, and the same parts as in FIG. 1 are given the same reference numerals.

In this figure, reference numeral 12 denotes a main body of a copying machine. A guide rail 13 is provided inside the main body 12 of the copying machine, and an optical scanning unit 14 moves on the guide rail 13.

18 is a shielding plate attached to the optical scanning unit 14, and when the optical scanning unit 14 reaches the position indicated by the broken line in the figure,
It is configured to block the optical axis of the position detection sensor 17 in the form of a photocoupler. The stepping motor 1 has a wire 19 between its output shaft and the guide rollers 15 and 16.
is stretched, and by fixing the optical scanning unit 14 to this wire 19, driving force is transmitted to the optical scanning unit 14. When the stepping motor 1 rotates in the direction of arrow A in the figure, the optical scanning unit 14 moves in the direction of arrow B in the figure (hereinafter referred to as the backward direction). Furthermore, when the stepping motor 1 rotates in the opposite direction to the direction of arrow A, the optical scanning unit 14 also moves in the opposite direction (hereinafter referred to as the forward direction).

Further, the optical scanning unit 14 is driven only at its end 14a, and the other end 14b is driven by a roller (not shown).
is provided, and is configured to slide on a sheet metal (not shown). Due to play between the optical scanning unit 14 and the guide rail 13 and insufficient rigidity of the optical scanning unit 14, when the acceleration on the end 14b side at the start of operation of the optical scanning unit 14 is measured, the acceleration characteristic shown in FIG. 5(a) is obtained. is obtained. The operation of FIG. 4 will be described below with reference to FIGS. 5(a) to 5(C).

FIG. 5(a) shows the optical scanning unit 14 shown in FIG.
2 is a diagram showing the speed characteristics of , where the vertical axis shows the frequency f and the horizontal axis shows the time t.

In this figure, the solid line shows the conventional slow-up speed characteristic, and the broken line shows the slow-up speed characteristic when the present invention is applied.

FIGS. 5(b) and 5(C) are diagrams showing the acceleration characteristics of the optical scanning unit 14 shown in FIG. 4, and the vertical axis is the frequency (
f), and the horizontal axis shows time (1).

In this figure, the solid line indicates the slow-up acceleration characteristic.

As can be seen from these figures, when the conventional slow-up speed control is executed, the time t
It reaches a constant speed (frequency ft) at 4, but at this time,
When the acceleration characteristic of the stepping motor 1 matches the peak of vibration as shown in FIG. 5(b), the amplitude of the acceleration becomes large due to this vibration. Therefore, the slow-up curve is changed and the time when the speed becomes constant (time from the start) is determined as the time ts shown in Fig. 5(a).
If the stepping motor 1 is controlled according to the procedure shown in FIG. 2 while adjusting to the time tp+tT (the vibration valley shown in FIG. 5(b)), the vibration will be constant with the vibration at the time of starting the stepping motor 1. The vibration at the time when the speed is reached is canceled out, resulting in the acceleration characteristic as shown in FIG. 5(C).

Note that the period of acceleration caused by the rise is determined by mechanical specification of the optical scanning unit 14, and is shown in FIG.
) is constant regardless of the rise curve. Therefore, if the stepping motor 1 is slowed up according to the control procedure shown in FIG.
; n is a positive natural number), it is possible to suppress the occurrence of vibration at the target speed.

In the above embodiment, a case has been described in which the value to be set in the timer is determined by calculation every time the stepping motor 1 moves one pulse. However, when the rotational speed of the stepping motor 1 increases, that is, the operating frequency As the value increases, the time required to perform calculations becomes non-negligible. Therefore, by calculating in advance the timer setting value until the constant speed is reached, the above-mentioned problem can be solved. However, it is necessary to store the above-mentioned timer setting value for each start-up time, and the storage capacity of the RAM 3c must be increased, which significantly increases the device cost.

However, one reference slow-up data table TA
Based on BLEI (see Figure 6), the slope is varied by setting the same value a predetermined number of times up to a certain timer set value, and subsequent slow-ups are performed according to the reference slow-up data table TABLEI. By continuing, the motor start-up completion time can be adjusted to the point between the accelerations of the stepping motor 1.

This case will be explained in detail below.

FIGS. 6(a) and 6(b) are schematic diagrams illustrating the reference slow-up data table stored in the ROM 3b shown in FIG. 1, and FIG. 6(a) shows the reference slow-up data table TABLEI, Timer set value TMS
1 to TMSN are stored. FIG. 7B shows a data table TABLE2, in which the return frequency values fM (fhlll to fMN) shown in FIG. 7 are stored.

FIG. 7 is a speed control characteristic diagram of a drive device showing another embodiment of the present invention, where the vertical axis shows frequency (f) and the horizontal axis shows time (1).

In this figure, STI shows a speed characteristic (linear speed characteristic) according to the reference slow-up data table TABLEI, and shows a case where the target drive frequency fe is reached at time tl.

NT2 indicates the slope change speed characteristic, and corresponds to the case where the multiple values of the reference slow-up data table TABLEI are set in the timer twice each until the return frequency value fM, and as a result, the slope of the slope change speed characteristic ST2 becomes the speed characteristic STI. The - slope of is 1/2.

NT3 indicates the speed characteristic after reaching the target drive frequency fe.

As can be seen from these figures, between the return frequency values fM of the data table TABLE2 stored in the ROM3b,
Use the timer set values TMSI, . . . of the reference slow-up data table TABLEI twice, and set the reference slow-up data table TABLE with the return frequency value f.
By setting the timer to return to the speed characteristic according to 1, the time to reach the target drive frequency fe can be adjusted to, for example, time t1□, and the timing at which the speed becomes constant can be adjusted freely.

Next, other drive control of the stepping motor 1 shown in FIG. 1 will be explained with reference to FIG. 8.

FIG. 8 is a flowchart illustrating an example of another drive control procedure for the stepping motor 1 shown in FIG. 1.

Note that (1) to (17) indicate each step. Also, P
OI NT, CPOI NT, 5etvalue
is a variable, and a storage location is secured in the RAM 3c. Further, TF and C0N5TF indicate flags, and fe indicates a target drive frequency.

First, the CPU 3a reads the reference slow-up data table T.
A pointer pointing to the data of ABLEI (variable PO
Reference slow-up data table TA B
Set the start address of LE 1 (1). Next, a data table TABL corresponding to the target drive frequency fe is created.
Set the data of E2 to the variable cpOINT (2).

Next, data at the address indicated by the variable POI NT is set in the variable 5etvaLUe (3). This results in
This means that the return frequency value fMl has been set.

Next, variable 5e is set for the internal timer of CPU 3a.
Set the value of tvalue 4), wait for the internal timer to complete timing 5), and when the timing is completed, switch the excitation pattern of the stepping motor 1 (6).

Therefore, the stepping motor 1 rotates for one pulse.

Next, the CPU 3a sets the value of the variable POI NT to the variable CP.
Please judge whether it is worse than the value of OI NT7)
If No, proceed to step (10) onward; if YES (YES up to the return frequency value fM), determine whether the flag TF is "1"(8); if No, set the flag TF to "1". (9) and return to step (4).

On the other hand, if YES, clear the flag TF to "0" (16) and add "1" to the value of the variable POI NT (17).
), return to step (3). As a result, the next data in the reference slow-up data table TABLEI, for example, the return frequency value fM2, is set to the variable 5etvalue.

On the other hand, if the determination in step (7) is NO, it is determined whether the flag C0N5TF is "1"10)
, if YES, return to step (4); if NO, add "1" to the value of variable POI NT11), variable 5et
The data at the address indicated by the value of the variable POI NT is set in value (12).

Next, the value of variable 5etvalue is the target drive frequency f
13), No.
If so, return to step (2), and if YES, flag C0
Set N5TF to "1"14), variable 5etva
Set the reciprocal number (period) of the target drive frequency fe to 15) and return to step (4).

In the above embodiment, the vibration of the optical scanning unit 14 is fixed, but an adjustment mechanism may be provided to accommodate slight variations between machines or changes over time.

In this case, in step (1) shown in FIG. 2, the first adjustment value AMEDI is set to the variable Trisa, and in step (1)
6), this can be handled by controlling the second adjustment value AMED2 to be set to the variable Trise. In addition,
First adjustment value AMED1. The second adjustment value AMED2 can be manually inputted to the CPU 3a by providing a variable resistor, for example.
Digital input may also be performed using a keyboard input method.

In addition, an acceleration sensor is provided in the optical scanning unit 14 provided with the drive device, and the first adjustment value AMED is detected in a preliminary operation.
The second adjustment value AMED2 may be measured and automatically adjusted.

Furthermore, in the above embodiment, the case where the drive device of the present invention is applied to the optical scanning unit 14 of a copying machine has been described.
For example, X-Y
It can also be applied to plotters, etc.

(Effects of the Invention) As explained above, the present invention provides a data memory that stores time data for starting a stepping motor to a plurality of target speeds in layers for each target speed, and a data memory that stores time data for starting a stepping motor to a plurality of target speeds, and corresponds to each set target speed. and a slow-up selection means for selecting one time data from the data memory and individually setting it in the mold motion control circuit, and changing the slow-up characteristic curve according to the target speed of the stepping motor. For example, in a copying machine or the like, vibrations at the time of starting the optical scanning unit can be suppressed with a relatively simple mechanical mechanism and a short run-up distance.

Therefore, excellent effects such as the ability to downsize the entire device including the drive device that drives the driven medium can be achieved at low cost and while maintaining high reliability.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram explaining the configuration of a drive device showing an embodiment of the present invention, FIG. 2 is a flowchart explaining an example of a stepper motor drive control procedure according to the present invention, and FIG. FIG. 4 is a plan view illustrating the drive mechanism of the optical scanning system of a copying machine to which the present invention is applied. FIG. Figures 5 (b) and 5 (C) are diagrams showing the speed characteristics of the optical scanning unit shown in Figure 4.
6(a) and (b) are schematic diagrams illustrating the reference slow-up data table stored in the ROM shown in FIG. 1, and FIG. 7 is a diagram showing the acceleration characteristics of the optical scanning unit shown in the figure. is a speed control characteristic diagram of a drive device showing another embodiment of the present invention, FIG. 8 is a flowchart explaining an example of another drive control procedure for the stepping motor shown in FIG. 1, and FIG. FIG. 3 is a diagram illustrating a stepping motor start-up control operation. In the figure, 1 is a stepping motor, 2 is a motor driver,
3 is a control circuit, 3a is a CPU, 3b is a ROM, 3c R
It is AM. (a) (b) (a) (b)

Claims (1)

[Claims] In a drive device including a stepping motor that transmits driving force to a driven medium and a drive control circuit that controls the speed of the stepping motor to be constant, time data for starting the stepping motor to a plurality of target speeds is provided. A data memory that stores each target speed individually, and one data memory that stores data for each set target speed.
1. A drive device comprising: slow-up selection means for selecting time data and individually setting it in the drive control circuit.