JPH1155998A - Stepping motor control equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid drive interruption when a mechanical load increases, by setting an operation pattern other than that which has been selected when step-up of a stepping motor is detected. SOLUTION: A control circuit 12 selects an operation pattern out of a plurality of operation patterns which are previously stored in a storage device 15. When a main CPU 13 detects the step-out of a scanner motor M1, the control circuit 12 selects another operation pattern out of those stored in the storage device 15, and performs a test operation of the scanner motor M1 via a drive circuit 14, in accordance with the selected operation pattern. When step-out is not generated, reciprocating operation from the next is performed by the selected operation pattern. When step-out is generated, the test operation is performed by selecting another operation pattern. As a result, operation patterns are changed over in order until step-out is not generated, and driving interruption can be avoided when a mechanical load increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stepping motor control device.

[0002]

2. Description of the Related Art Stepping motors are widely used for driving precision equipment such as image scanners because of their relatively high positioning accuracy. However, the stepping motor loses synchronism when a load larger than the generated torque is applied, and is not controlled stably.

Therefore, conventionally, control is performed to monitor the presence or absence of step-out of the stepping motor, determine that a trouble has occurred when step-out of the stepping motor has occurred, and stop the drive of the stepping motor ( For example, see JP-A-3-293860.

[0004]

However, in the conventional method, when the mechanical load increases, for example, when the load torque increases due to the presence of a large amount of dust or yellow sand, the driving of the stepping motor is stopped. Therefore, there is a problem that the device cannot be used.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stepping motor control device capable of minimizing stoppage of driving of a stepping motor even when a mechanical load increases.

[0006]

According to a first aspect of the present invention, there is provided a stepping motor control apparatus comprising:
Step-out detection means for detecting the presence / absence of step-out of the stepping motor, storage means for storing an operation pattern for the stepping motor, and one operation pattern stored by the storage means, and according to the selected operation pattern, A drive unit for driving the stepping motor, and when the step-out detection unit detects step-out of the stepping motor, a control unit that sets another operation pattern instead of the one operation pattern is provided. I do.

In the stepping motor control device according to the first aspect of the invention, when the stepping motor is driven according to one operation pattern stored in the storage means, the step-out detecting means detects step-out of the stepping motor. The control means sets another operation pattern instead of one operation pattern. The test operation of the stepping motor is performed according to the operation pattern after the switching, and when the step out of the stepping motor is eliminated, the driving of the stepping motor is continued according to the operation pattern after the switching. If the switching does not eliminate the stepping motor out-of-step, the control means selects another operation pattern and performs a stepping motor test operation. In this manner, a new operation pattern is set until the step out of the stepping motor is eliminated. Therefore, even if the mechanical load increases, it is possible to avoid stopping the driving of the stepping motor as much as possible. As a result, the operation stop (machine down) of the device to which the stepping motor is applied can be avoided as much as possible.

According to a second aspect of the present invention, in the stepping motor control device according to the first aspect, the storage means stores a plurality of types of operation patterns for the stepping motor, and the control means includes: Another operating pattern replacing the one operating pattern is set by selecting from a plurality of types of operating patterns stored in the storage means.

In the stepping motor control device according to the second aspect, since the storage means selects and sets another operation pattern from a plurality of types of operation patterns stored in advance, switching of the operation pattern by the control means is performed. It is performed smoothly in a short time.

According to a third aspect of the present invention, there is provided a stepping motor control device according to the first aspect, wherein the control means replaces another operation pattern in place of the one operation pattern with the one operation pattern. , Which are created and set by performing an operation.

In the stepping motor control device according to the third aspect, the control means creates and sets another operation pattern in place of the one operation pattern by performing an operation on the one operation pattern. The capacity of the means is small.

According to a fourth aspect of the present invention, in the stepping motor control device according to the second aspect, the control means includes the one operation pattern as another operation pattern replacing the one operation pattern. In contrast to the above, an operation pattern in which the rising gradient and the decreasing gradient of the rotation speed of the stepping motor are gentle is selected and set.

In the stepping motor control device according to the fourth aspect, as another operation pattern replacing the one operation pattern, the rising gradient and the decreasing gradient of the rotation speed of the stepping motor are different from the one operation pattern. Since a gentle driving pattern is selected and set, the acceleration can be kept low. Therefore, there is a high possibility that the step out of the stepping motor is eliminated.

According to a fifth aspect of the present invention, in the stepping motor control device according to the second aspect, the control means includes the one operation pattern as another operation pattern in place of the one operation pattern. The operation pattern is characterized by selecting and setting an operation pattern in which the ultimate rotation speed of the stepping motor is lower than that of the stepping motor.

In the stepping motor control device according to the fifth aspect, as another operation pattern replacing the one operation pattern, as another operation pattern replacing the one operation pattern, compared with the one operation pattern, Since an operation pattern with a low ultimate rotation speed of the stepping motor is selected and set, high-speed rotation, which tends to lack torque, can be avoided. Therefore, there is a high possibility that the step out of the stepping motor is eliminated.

According to a sixth aspect of the present invention, in the stepping motor control device according to the second or third aspect, the control means includes the one operation pattern as another operation pattern replacing the one operation pattern. It is characterized in that an operation pattern is set in which the steepest gradient of the gradients of the operation pattern is changed to a gentler gradient.

In the stepping motor control device according to the sixth aspect, as another operation pattern replacing the one operation pattern, the steepest gradient of the one operation pattern is changed to a gentler gradient. Since the driving pattern is set, the acceleration in the section where the step-out has occurred can be kept low. Therefore, there is a high possibility that the step out of the stepping motor is eliminated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the stepping motor control device according to the present invention will be described in detail.

It is assumed that a stepping motor (hereinafter referred to as "scanner motor") M1 for driving an image scanner 1 of a copying machine as shown in FIG. 1 is controlled.

The scanner motor M1 is connected to a drive pulley 7 via a timing belt 6 at a reduction ratio of 1: 4. A wire 8 is wound around the driving pulley 7 and the idle pulleys 9 and 10. The wire 8 is connected to the scanner 1 via a pulley 11 fixed to the mirror slider 2.

The scanner 1 is provided with components such as an exposure lamp and a first mirror. When the exposure lamp irradiates a document (not shown) placed on the document glass with light, the reflected light is reflected by a first mirror provided on the scanner 1, a second mirror provided on the mirror slider 2, and a second mirror provided on the mirror slider 2. The light is reflected by the third mirror, reaches a surface of a photoconductor (not shown) via a lens (not shown) and a fourth mirror, and forms an image there.

One end in the longitudinal direction of the scanner 1 and the mirror slider 2 (the end on the far side in FIG. 1) is slidably fitted to a fixed scanner shaft 4 extending in one direction. On the other hand, a slide roller 3 that slides on a rail (not shown) is attached to opposite ends of the scanner 1 and the mirror slider 2 in the longitudinal direction. Thus, the scanner 1 and the mirror slider 2 can freely move in parallel along the scanner shaft 4.

When the scanner motor M1 rotates, the scanner 1 and the mirror slider 2 are driven via the wire 8 and the pulley 11, and move in parallel along the scanner shaft 4. More specifically, when the scanner motor M1 rotates forward from a predetermined rotation angle, the drive pulley 7 rotates via the timing belt 6, and the wire 8 moves. In response to the movement of the wire 8, the scanner 1 moves forward from the home position along the document surface, and at the same time, the mirror slider 2 moves at half the speed. Thus, the entire surface of the document is scanned. When the scanner motor M1 rotates in the reverse direction, the scanner 1 and the mirror slider 2 move back toward the home position. Such an operation is performed for each document, and each document is read.

A home position sensor 5 composed of a photo interrupter is provided near the end of the scanner shaft 4 on the near side in FIG. 1 to detect the initial position of the scanner 1. The home position sensor 5 emits light for detecting the scanner position toward the scanner 1. A shield plate is attached to the scanner 1, and only when the scanner 1 is located at the home position, the light from the home position sensor 5 is shielded by the shield plate. Thereby, it is detected whether the scanner 1 is located at the home position. The home position sensor 5 outputs a home position signal that turns on when the scanner 1 is at the home position and turns off when the scanner 1 is not at the home position. As described below,
This home position signal is used to detect the presence / absence of step-out of the scanner motor M1.

FIG. 2 shows a block configuration of a stepping motor control device 90 of one embodiment for controlling the scanner motor M1. The stepping motor control device 90 includes a main CPU (central processing unit) 13 and a control circuit 12 as control means, a memory 15 as a storage means for storing a plurality of operation patterns for a scanner motor, and a control circuit 2. And a drive circuit 14 for driving the scanner motor M1 with a predetermined pulse voltage in accordance with the output signal. Reference numeral 5 denotes the above-described home position sensor. The scanner motor M1 rotates forward or backward by a rotation angle corresponding to the number of input pulses, and its rotation speed is determined according to the frequency f (unit: pps (pulse per second)) of the input pulse. Can be

The main CPU 13 controls the entire apparatus and outputs a command to the control circuit 12. The control circuit 12 communicates with the main CPU 13 and
When a scanning start command is received from the memory 13, one operation pattern as shown in FIG. 3A is selected from a plurality of operation patterns stored in the memory 15 in advance.

[0027] In the operation pattern, to start forward rotation of the scanner motor M1 at time t _0, the motor speed is increased (accelerated) at a constant gradient from the time t ₀ to t _1, the time t ₁
From maintaining a constant rotational speed f ₁ to t _2, the motor rotation speed is lowered (deceleration) at a constant gradient from the time t ₂ to t _3, and terminates the forward rotation of the scanner motor M1 at time t _3.
Further, to start the reverse rotation of the scanner motor M1 at time t ₄ after the predetermined time has elapsed from the time t _3, from time t ₄ to increase the motor rotation speed at a constant gradient up to t _5, from time t ₅ to t ₆ maintaining a constant rotational speed f _2, from time t ₆ to t ₇ lowers the motor rotation speed at a constant gradient, and ends the reverse rotation of the scanner motor M1 at time t _7.

When the step-out of the scanner motor M1 does not occur, the scanner 1 moves forward and backward according to this operation pattern, and the original is scanned. After the scanning of the document is completed, the scanner 1 returns to the home position. The home position sensor 5 turns on the home position signal. When receiving the ON-level home position signal from the home position sensor 5, the control circuit 12 immediately transmits a scan end command to the main CPU 13.

[0029] If the step-out of the scanner motor M1 does not occur, the time required for one reciprocation (t ₇ -t ₀₎ is a constant. Therefore, when the home position signal is turned on again after a lapse of time (t ₇ -t ₀ ) from the start of the forward movement,
The main CPU 13 can confirm that step-out of the scanner motor M1 has not occurred.

Here, it is assumed that the mechanical load becomes heavy due to a change over time or the like. As a result, if the scanner motor M1 loses synchronism during the backward movement, the time (t) from the start of the forward movement
_{Since the} home position signal is not turned on even after ₇₋ t ₀ ) has elapsed, the main CPU 13 can easily detect that step-out has occurred. Similarly, when the scanner motor M1 steps out during the forward movement, the time (t ₇ -t ₀ ) from the start of the forward movement
Because the home position signal is turned on before elapses,
The main CPU 13 can easily detect that step-out has occurred. It should be noted that it is determined that the step-out has actually occurred because a predetermined time Δ with respect to the original round-trip time (t ₇ −t ₀ ).
It is desirable that the difference be greater than or equal to t. This is to avoid erroneous detection because a slight time lag occurs due to various factors even in a normal reciprocating operation.

When the main CPU 13 detects step-out of the scanner motor M1 in this manner, the main CPU 13
From the plurality of operation patterns stored in the memory 5, the control circuit 12 replaces the operation pattern of FIG. 3A with a gentle gradient as shown in FIG. Select an operation pattern.

[0032] In this operation pattern, the forward rotation and the start of the scanner motor M1 at time t _0, from time t ₀ 'increasing the motor speed at a constant gradient until the time t _1' t ₁ from to t ₂ ' maintaining a constant rotational speed f _1, lowers the motor rotation speed at a constant gradient 'from t _3' time t ₂ to to time t ₃ 'ends of the forward rotation of the scanner motor M1. Further, to start the reverse rotation of the scanner motor M1 to 'time t ₄ after a certain time has elapsed from the' time t _3, time t ₄ 'from t _5'
Increasing the motor speed at a constant gradient to maintain a constant rotational speed f ₂ 'from t _6' time t ₅ to lowers the motor rotation speed at a constant gradient 'from t _7' time t ₆ to , to end the reverse rotation of the scanner motor M1 to time t ₇ '. Each of the attained rotation speeds f ₁ ,
f ₂ is the same as that of the operation pattern of FIG.
As can be seen by comparing FIG. 3A and FIG. 3B, (t ₁ ′ −t ₀ )> (t ₁ −t ₀ ) (t ₃ ′ −t ₂ ′)> (t ₃ − _{t 2) (t 5 '-t} 4')> (t 5 -t 4) (t 7 '-t 6')> is set to (t ₇ -t _6). That is, the gradient of each of the acceleration section and the deceleration section of the operation pattern of FIG. 3B is set to be gentler than the gradient of the corresponding section of the operation pattern of FIG. Along with this, the original time required for reciprocating movement of the scanner 1 (t ₇ '-t ₀₎ becomes, (t ₇
−t ₀ ).

The control circuit 12 performs a test operation of the scanner motor M1 via the drive circuit 14 in accordance with the operation pattern shown in FIG. The scanner motor M is determined based on whether or not a shift of a predetermined time Δt or more occurs with respect to the original reciprocating time (t ₇ ′ −t ₀ ) after the switching of the operation pattern.
Check if 1 steps out. If there is no step-out,
The reciprocating operation from the next time is performed according to the operation pattern shown in FIG.

On the other hand, if a step-out occurs even in the operation pattern shown in FIG. 3B, another operation pattern having a further gentler slope is selected from the memory 5 and a test operation is similarly performed. Check if a tone occurs.

In this manner, the operation patterns are sequentially switched until the step-out of the scanner motor M1 does not occur. Then, when the step-out stops, the reciprocating operation from the next time is performed according to the operation pattern. Therefore,
Even if the mechanical load increases, it is possible to avoid stopping the driving of the stepping motor as much as possible. As a result,
The operation stop (machine down) of the device to which the stepping motor is applied can be avoided as much as possible.

When an operation pattern having an extremely gentle gradient is employed, the time required for the reciprocating operation of the scanner 1 becomes too long, and the specifications of the image scanner section may not be satisfied. In that case, as described below,
It is desirable to provide a display unit for notifying a user of information indicating that the reciprocating operation time of the scanner has become longer.

FIG. 4 shows a display section 91 on an operation panel of a copying machine to which the present stepping motor control device is applied. The display section 91 includes a number display section 16 for displaying the set number of copies, a magnification / magnification display section 17 for displaying the set magnification, a paper size display section 18 for displaying the set paper size, It has a comment display section 19 for displaying a code and a comment for urging a contact with a service person. Using a communication line, the copier can notify the nearest service station that an error has occurred in the scanner 1.

Actually, the acceleration section in the forward movement needs to be completed before the scanner 1 reaches the exposure start position of the original. That is the limit where the gradient of the driving pattern can be made the gentlest. If the step-out still occurs even after the switching has been performed for all the operation patterns stored in the memory 5, the device is stopped as in the related art, assuming that a trouble has occurred. At that time, the comment display section 19 displays
Displays a trouble code and a comment that prompts a service person to contact you.

Generally, a stepping motor has a property that the torque decreases as the number of rotations increases. Therefore, the gradient (acceleration) of the acceleration section and deceleration section of the driving pattern
In addition to changing the maximum speed, step-out can be avoided by lowering the maximum speeds f ₁ and f ₂ . Also, the step-out can be avoided by gradually changing only the gradient of the steepest section, instead of making the gradient gentle for all acceleration sections and deceleration sections.

Instead of storing a plurality of operation patterns, the memory 15 may store only one operation pattern. In this case, the scanner motor M1
When a step-out occurs, a new operation pattern is created by calculation, and the scanner motor M1 is driven in accordance with the new operation pattern.

Of course, in addition to detecting step-out due to a time lag from the original reciprocating time of the scanner 1, it is also necessary to attach an encoder to the scanner motor M1 or the driving pulley 7 and monitor the rotation thereof. Step out can also be detected.

In this embodiment, the case where the driving of the scanner motor M1 for driving the image scanner 1 is controlled has been described. However, the present invention is widely applied to a stepping motor for moving a lens, a stepping motor for conveying paper, and the like. Can be applied.

[0043]

As is apparent from the above description, the stepping motor control device according to the first aspect of the present invention performs step-out detection by the step-out detecting means even if stepping motor step-out occurs due to an increase in mechanical load. Since the detection is performed and the control means sets another operation pattern instead of one operation pattern, it is possible to avoid stopping the driving of the stepping motor as much as possible. Therefore, it is possible to minimize the operation stop (machine down) of the device to which the stepping motor is applied.

In the stepping motor control device according to the second aspect, the storage means selects and sets another operation pattern from a plurality of types of operation patterns stored in advance.
Switching of the operation pattern by the control means can be performed smoothly in a short time.

According to a third aspect of the present invention, the control means creates and sets another operation pattern in place of the one operation pattern by performing an operation on the one operation pattern. Requires less capacity.

In the stepping motor control device according to the fourth aspect, as another operation pattern replacing the one operation pattern, the rising gradient and the decreasing gradient of the rotation speed of the stepping motor are gentler than the one operation pattern. Since an appropriate driving pattern is selected and set, the acceleration can be kept low. Therefore, the possibility that the step-out of the stepping motor is eliminated can be increased.

According to a fifth aspect of the present invention, in the stepping motor control device, as another operation pattern replacing the one operation pattern, another operation pattern replacing the one operation pattern is compared with the one operation pattern. Since an operation pattern with a low ultimate rotation speed of the stepping motor is selected and set, it is possible to avoid a high-speed rotation that tends to lack torque. Therefore, the possibility that the step-out of the stepping motor is eliminated can be increased.

In the stepping motor control device according to a sixth aspect, as another operation pattern replacing the one operation pattern, an operation in which the steepest gradient of the one operation pattern is changed to a gentler gradient is performed. Since the pattern is set, the acceleration in the section where the step-out has occurred can be suppressed low. Therefore, the possibility that the step-out of the stepping motor is eliminated can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an image scanner to which a stepping motor control device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a configuration of the stepping motor control device.

FIG. 3 is a diagram showing an operation pattern of a stepping motor by the stepping motor control device.

FIG. 4 is a diagram illustrating an example of a display unit of the copying machine.

[Explanation of symbols]

 M1 scanner motor 1 scanner 90 stepping motor control device 91 display unit

Claims (6)

[Claims] An out-of-step detecting means for detecting the presence / absence of out-of-step of a stepping motor; a storage means for storing an operation pattern for the stepping motor; and an operation pattern stored in the storage means, A drive unit for driving the stepping motor according to the selected operation pattern, and a control unit for setting another operation pattern instead of the one operation pattern when the step-out detection unit detects the step-out of the stepping motor. A stepping motor control device. 2. The stepping motor control device according to claim 1, wherein the storage unit stores a plurality of types of operation patterns for the stepping motor, and the control unit performs another operation in place of the one operation pattern. A stepping motor control device, wherein a pattern is selected and set from a plurality of operation patterns stored in the storage means. 3. The stepping motor control device according to claim 1, wherein the control means creates and sets another operation pattern in place of the one operation pattern by performing an operation on the one operation pattern. A stepping motor control device, comprising: 4. The stepping motor control device according to claim 2, wherein the control means controls the rotation of the stepping motor as another operation pattern in place of the one operation pattern as compared with the one operation pattern. A stepping motor control device characterized by selecting and setting an operation pattern in which a rising gradient and a falling gradient of a speed are gentle. 5. The stepping motor control device according to claim 2, wherein the control means determines that the stepping motor reaches the stepping motor as another operation pattern in place of the one operation pattern as compared with the one operation pattern. A stepping motor control device, wherein an operation pattern having a low rotation speed is selected and set. 6. The stepping motor control device according to claim 2, wherein the control means includes, as another operation pattern replacing the one operation pattern, a steepest slope of the one operation pattern. A stepping motor control device which sets an operation pattern obtained by changing the gradient to a gentler gradient.