JP3783455B2 - Stepping motor control device, control method, and printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stepping motor control apparatus and method.
[0002]
[Prior art]
In a printer that employs a stepping motor as a drive source for the carriage or paper feed mechanism, the carriage or paper feed speed is controlled by switching the excitation method. For this reason, there is known a control device that drives a stepping motor by an ASIC or the like by a plurality of excitation methods in hardware, for example, excitation methods such as one-phase, 2-2 phase, 1-2 phase, or W1-2 phase. . Of course, such a control device is not limited to a printer, and is often used for devices that need to control the speed of a stepping motor. One of such control devices is a system using a counter for generating a phase excitation signal. This counter (hereinafter, phase excitation counter) is prepared based on the number of states in the phase excitation table created based on the excitation method (phase excitation mode) having the largest number of states (step angle, stepping angle). Therefore, when the stepping motor is driven in the phase excitation mode with the smallest number of states compared to the phase excitation mode with the largest number of states, the counter value updated in one step should be doubled or quadrupled. Thus, a phase excitation signal suitable for the state is output.
[0003]
[Problems to be solved by the invention]
In this apparatus, when the excitation method is switched, that is, when the phase is switched, it must be performed at a step angle that the rotor can take in the switching excitation method. For this reason, when performing phase switching, the step angle of the stepping motor must be confirmed in software or hardware to determine the timing for phase switching. Alternatively, when creating a program for driving the stepping motor, it is necessary to consider in units of steps so that phase switching is performed at a step angle without error.
[0004]
The method of phase switching when an appropriate step angle is obtained while constantly monitoring the step angle of the stepping motor requires hardware and monitoring time for monitoring, and further steps when phase switching should be performed. If the angle is not appropriate, the phase cannot be switched immediately. Therefore, the control speed cannot be made so fast, and there are few advantages in terms of cost. Furthermore, the response speed of phase switching may be reduced. For this reason, controllability is not good. Even if the phase is switched without monitoring the step angle, the stepping motor may still be able to rotate as it is, but the rotor is likely to rotate at a step angle that does not match the excitation method. In addition, the durability of the stepping motor is also adversely affected.
[0005]
On the other hand, if the sequence or program for controlling the stepping motor is clearly defined for each step, there is no concern about noise and the like, and the phase can be switched at an appropriate timing. However, it takes a lot of time and labor to program the stepping motor in units of step angles in consideration of various conditions, and the development cost increases. Also, it is often the case that the step angle fluctuates due to some impact or an unintended factor when creating a program. In such a situation, the step angle at the time of phase switching is no longer appropriate, so noise, vibration, etc. The same problem as above occurs.
[0006]
Therefore, in the present invention, it is possible to save the trouble of constantly checking until the switchable step angle is reached when the phase is switched. On the other hand, even if the step angle at the timing of phase switching is not appropriate, vibration or An object of the present invention is to provide a control device and a control method capable of phase switching without generating noise or the like.
[0007]
In addition, if the step angle at the time of phase switching is not appropriate for some reason, some abnormality has occurred. However, in the method of constantly monitoring the step angle, since the phase is switched when the appropriate step angle is reached, such an abnormality is not found. Further, when a sequence or program that has been studied in detail is used, it is not known whether or not an abnormality has occurred.
[0008]
Therefore, an object of the present invention is to provide a control device and a control method capable of determining that the step angle is unexpected, that is, not an appropriate step angle at the phase switching timing.
[0009]
[Means for Solving the Problems]
For this reason, in the present invention, a binary counter that cyclically counts all step angles of the stepping motor is prepared. When the step angle of the excitation method does not match at the phase switching timing, the counter value is set. The correction is forcibly made. Further, the step angle for correction is a time that is not a suitable angle such as 2 or 4 times the minimum step angle, which is a step angle suitable for the excitation method of the switching destination. Therefore, it can be easily corrected by forcibly setting an appropriate bit string from the least significant bit or the least significant bit of the binary counter to 0 by hardware or software.
[0010]
That is, in the control device capable of driving the stepping motor by a plurality of excitation methods according to the present invention, the binary counter that counts all step angles cyclically with the bit for counting the minimum step angle of the stepping motor as the least significant bit. A phase excitation counter that can generate a phase excitation signal of the corresponding step angle, an update means that increases or decreases the value of the phase excitation counter according to the rotation direction of the stepping motor and the excitation method, and a phase when the excitation method is switched. When the value of the excitation counter does not correspond to the excitation method after switching, before updating the phase excitation counter by the updating means, the least significant bit or the lower bit string of the phase excitation counter according to the excitation method after switching And a correction means for setting 0 to 0.
[0011]
Further, the present invention is a binary counter that counts the minimum step angle of the stepping motor of the present invention as the least significant bit and cyclically counts all the step angles, and can generate a phase excitation signal of the corresponding step angle. In a control method that uses a counter and drives a stepping motor with a plurality of excitation methods, an update process that increases or decreases the value of the phase excitation counter according to the rotation direction of the stepping motor and the excitation method, and the phase excitation counter value when the excitation method is switched. When the value does not correspond to the excitation method after switching, a correction step of setting the least significant bit or the lower-order bit string of the phase excitation counter according to the excitation method after switching to 0 before the updating step is included .
[0012]
In the control apparatus and control method of the present invention, when the step angle does not match when switching the excitation method, the least significant bit of the phase excitation counter, or a lower-order bit string including the least significant bit depending on the excitation method By setting 0 to 0, the phase excitation counter is corrected to a count corresponding to the excitation method, and then the phase excitation counter is updated according to the excitation method and the rotation direction. Therefore, even when the step angle does not match when switching the excitation method, there is no need to wait while monitoring until the step angle is suitable, and the nearest step angle that matches the excitation method after switching is phase excited. Later, it can be moved at a step angle that matches the excitation method after the switching. For this reason, the phase can be switched whenever necessary. Furthermore, even when the step angle is not compatible, the step angle is corrected to the step angle that matches the excitation method after switching, so that noise and vibration do not occur. Further, it does not affect the life of the stepping motor.
[0013]
Furthermore, because the control device and the control method of the present invention smoothly perform phase switching even when the step angle does not match when switching, the details for each step angle when developing a sequence or program for controlling a stepping motor are also provided. You do not have to consider it. For this reason, these development periods and costs can be significantly reduced.
[0014]
Also, by providing abnormality monitoring means that can memorize that the phase excitation counter has been forcibly operated by the correction means, the step angle can be set at the timing at which the step angles are supposed to coincide in order to switch the excitation method. The shifted abnormality can be detected. Therefore, the abnormality included in the program or sequence can be easily confirmed and debugged. Further, when abnormal noise or abnormal vibration occurs while driving a device such as a printer equipped with a stepping motor, it can also be confirmed whether or not the control of the stepping motor is the cause.
[0015]
When a 4-phase stepping motor is driven by the 2-2 phase, 1-2 phase, and W1-2 phase excitation methods using the control device and control method of the present invention, a 4-bit counter can be adopted as the phase excitation counter. In the correction means or the correction process, when the excitation method after switching is 1-2 phase, the least significant bit of the phase excitation counter is forcibly set to 0, and when the excitation method after switching is 2-2 phase, the phase is The two bit strings may be forced to 0 from the least significant bit of the excitation counter.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described below with reference to the drawings. FIG. 1 shows a printer equipped with a control device according to the present invention. The printer 1 of this example is a serial type printer in which a printing head 2 such as an inkjet method or an impact dot method reciprocates in the scanning direction of the printing paper 5. The carriage 3 on which the head 2 is mounted is driven in the scanning direction, in the right and left directions in the drawing, by a driving mechanism such as a timing belt 4, and a stepping motor 10 is employed as a driving source for the timing belt 4. The print head 2 may be driven at a plurality of speeds, for example, the speed at which the print head 2 moves to a position where printing is started differs from the speed at which printing is performed. In such a case, it is controlled by changing the excitation method for driving the stepping motor 10. Not only the print head 2 but also a paper feed mechanism (not shown) of the printing paper 5 has a different paper feed speed and printing speed, and the control in that case is performed in the same way.
[0017]
The printer 1 of this example is driven by supplying a driving pulse of appropriate effective power from the control circuit 30 to the stepping motor 10. The control circuit 30 includes an excitation method selection register (mode register) 32 in which the excitation method of the stepping motor 10 is set, a direction instruction register 33 in which the rotation direction is set, and other setting conditions such as a phase switching described later. Is provided with an initial setting register 31 for setting the presence / absence of correction movement. The control circuit 30 further includes a phase excitation counter 35 that can define each step angle of the rotor 11. According to the value of the phase excitation counter 35, a drive pulse of appropriate effective power and polarity is supplied from the drive circuit 20. Is supplied to each of the coils L1, L2, L3 and L4. The phase excitation counter 35 is counted up or down by the counter control unit 40 that operates according to the contents of the registers 31, 32, and 33 in which conditions for driving the stepping motor 10 are set.
[0018]
The counter control unit 40 judges the contents of the register 31, 32 or 33, and performs central control 41 for performing overall control, and update for adding or subtracting a predetermined count to the phase excitation counter 35 according to the rotation direction And a correction unit 43 that forcibly corrects the value of the counter 35 when the value of the phase excitation counter 35 is not appropriate when switching the excitation method. Further, an abnormality output unit 44 that sets in the abnormality monitor register 39 that the correction unit 43 has forcibly changed the value of the phase excitation counter 35 is provided. The counter control unit 40 having such a function can be realized in hardware by a state machine, or can be realized by a microprogram.
[0019]
Hereinafter, an example will be described in which the four-phase stepping motor 10 is driven by switching the excitation method of the 2-2 phase, 1-2 phase, and W1-2 phase. FIG. 2 shows the value of the phase excitation counter 35 and the phase excitation signal supplied to the stator 12 of the stepping motor 10 in each excitation method. The phase excitation counter 35 is a binary counter, and a 4-bit counter is employed in accordance with the 16-step angle of the W1-2 phase having the largest number of step angles. As shown in FIG. 2C, when the stepping motor 10 is driven in the W1-2 phase, in the phase excitation counter 35, the least significant bit is counted up or down. The state number 36 corresponds to a step angle at which the rotor 11 can be controlled. Therefore, a common state number is used for the 2-2 phase shown in FIG. 2A, the 1-2 phase shown in FIG. 2B, and the W1-2 phase shown in FIG. 2C. The angle of the rotor 11 can be known by referring to the state number. The phase excitation signal 37 indicates the signal level supplied to the coils L1, L2 and L3, L4 constituting the A phase and the B phase, and the ratio is further shown in the table.
[0020]
Thus, in the control circuit 30 of this example, the phase excitation signal 37 is uniquely set with respect to the value of the phase excitation counter 35. Therefore, by setting the value of the phase excitation counter 35, an appropriate drive pulse is supplied to the stepping motor 10 and the rotor 11 can be rotated by a predetermined angle. Further, the phase excitation counter 35 of this example is a binary counter, and the W1-2 phase state having the largest number of states can be defined using the least significant bit. Accordingly, in the 1-2 phase where the number of states is eight, which is 1/2, as shown in FIG. 2B, the phase excitation counter 35 is incremented or decremented by two, that is, by binary "10". Thus, a phase excitation signal in a state in which the rotor 11 moves by the 1-2 phase excitation method can be output. Similarly, in the 2-2 phase excitation method in which the number of states is four, the phase excitation counter 35 is counted up or down by four, that is, by binary “100”, so that the state that matches this excitation method can be obtained. A phase excitation signal can be output.
[0021]
Therefore, for example, when switching from the W1-2 phase excitation method to the 1-2 phase excitation method, it is necessary to output a phase excitation signal in a common state. This can be easily determined by determining whether the least significant bit of the phase excitation counter 35 is “0”. Further, when switching to the 2-2 phase excitation method, it is possible to easily determine whether or not it is a switchable state based on whether or not the two lower bits of the phase excitation counter 35 are “00”.
[0022]
Furthermore, when the state at the time of phase switching is not common with the excitation method after switching, when the excitation method after switching is 1-2 phase, the least significant bit of the phase excitation counter 35 is forcibly set to “0”. ”And adding or subtracting binary“ 10 ”according to the direction of rotation, it is closest to the state at the time of phase switching, and the state of the state corresponding to the excitation method after switching, that is, the 1-2 phase excitation method. A phase excitation signal can be output. Therefore, thereafter, the phase excitation counter 35 is updated by the 1-2 phase excitation method, so that the phase excitation signal of a predetermined state (step angle) can be sequentially output. When switching to the 2-2 phase excitation method, the lower 2 bits are forcibly set to “00” and then the binary “100” is increased or decreased according to the rotation direction.
[0023]
Based on the flowchart shown in FIG. 3, the operation of the control device 30 of this example will be further described. First, in step 51, the initial register 31, the mode register 32, and the rotation direction register 33 are initialized. At this time, the initial excitation phase is also set in the phase excitation counter 35. The initial excitation phase may be set directly in the phase excitation counter 35, or an area for setting the initial excitation phase may be provided in the initial setting register.
[0024]
Next, in step 52, the state abnormality is checked. That is, it is checked whether the initial excitation phase set in the phase excitation counter 35 matches the excitation method set in the mode register 32. If the 2-2 phase is set, the lower 2 bits of the phase excitation counter 35 need to be “00”. If the 1-2 phase is set, the least significant bit of the phase excitation counter 35 needs to be “0”.
[0025]
If the value of the phase excitation counter 35 does not match the excitation method set in the mode register 32, there is some abnormality in the state of the program or the machine. In step 53, the abnormality output register 44 makes the abnormality monitor register 39 abnormal. set. Thereby, it can be clearly determined later whether or not an abnormality has occurred during the job. It is also possible to stop the operation of the printer or the like when an abnormality is set in the abnormality monitor register 44 so that the user or operator can check the content of the abnormality. Such settings can be easily included in the initial setting register and changed for each job.
[0026]
If the value of the phase excitation counter 35 does not match the excitation method set in the mode register 32, the correction unit 43 corrects the value of the excitation next counter 35 in step 54. When the 2-2 phase is set, the lower 2 bits of the phase excitation counter 35 are set to “00”. When the 1-2 phase is selected, the least significant bit of the phase excitation counter 35 is set to “0”. To do. When the W1-2 phase is set, any state that can be set in the phase excitation counter 35 can be selected, so it is not necessary to check the value of the phase excitation counter 35.
[0027]
If no state abnormality is found in step 52, or if the value of the phase excitation counter 35 is corrected to match the excitation method in step 54, the rotation direction set in the rotation direction register 33 in step 55, Based on the excitation method set in the mode register 32, the value of the phase excitation counter 35 is updated by the updating unit 42.
[0028]
In this example, when the rotation direction is CCW (counterclockwise) in the 2-2 phase, binary “0100” is added to the phase excitation counter 35. When the rotation direction is CW (clockwise) in the 2-2 phase, the binary “0100” is subtracted from the phase excitation counter 35. Similarly, in this example, when the rotation direction is CCW in the 1-2 phase, binary “0010” is added to the phase excitation counter 35, and when the rotation direction is CW, the binary excitation “35” is output from the phase excitation counter 35. Reduce "0010". Further, when the rotation direction is CCW in the W1-2 phase, binary “0001” is added to the phase excitation counter 35, and when the rotation direction is CW, binary “0001” is subtracted from the phase excitation counter 35.
[0029]
Thus, by updating the value of the phase excitation counter 35, the phase excitation signal of the next state in each excitation method and rotation direction is output, and the rotor 11 rotates.
[0030]
In step 55, when an instruction to change the excitation method is input to the control device 30, it is confirmed in step 57 whether or not the motor 10 is to be stopped. If a command to stop is output, the drive pulse from the drive circuit 20 is stopped in step 58 to stop the rotation of the rotor 11. On the other hand, if the instruction is not to stop the motor 10, the new excitation method is stored in the mode register 32 in step 59, and the process returns to step 52 to check whether the count value of the phase excitation counter 35 matches the new excitation method. Judging.
[0031]
The processing in steps 52, 53 and 54 when there is an instruction to change the excitation method while driving the motor 10 is the same as described above. First, in step 52, for example, when changing from the W1-2 phase to the 2-2 phase according to the excitation method after switching, it is confirmed whether the lower 2 bits of the phase excitation counter 35 are 0 and do not match. In step 53, the abnormality monitor register 39 is set. Then, the lower 2 bits of the phase excitation counter 35 are forcibly set to “00” in step 54, and thereafter, if the direction is CCW, binary “0100” is added. Therefore, when the phase is switched to 2-2 phase during driving in the W1-2 phase, even if it is not in the 2-2 phase state, phase excitation is performed to the 2-2 phase state closest to the switching state. The counter 35 is set and the phase excitation signal is output. After the excitation method is switched, the value of the phase excitation counter 35 changes at a 2-2 phase pitch. The same applies when switching the excitation method from the W1-2 phase to the 1-2 phase, or from the 1-2 phase to the 2-2 phase.
[0032]
As described above, in the control device 30 and the control method of this example, even when the state of the stepping motor 10 does not match the excitation method after switching at the timing of switching the excitation method, the correction unit 43 forcibly complies with the excitation method. By operating the excitation counter 35 and then updating the counter 35, the stepping motor 10 can be driven in the state of the excitation method after switching. In this example, since a binary counter is used, it is only necessary to forcibly set the lower bits corresponding to the excitation method after switching to 0 for correction. For this reason, it is not necessary to know the state number at the time of switching or to calculate the state number after switching, and the value of the phase excitation counter 35 can be appropriately corrected with simple hardware or software.
[0033]
Therefore, by adopting the control device and the control method of this example, when phase switching is performed to change the speed of the stepping motor, the step angle (state) is monitored and the timing becomes an appropriate step angle. No hardware or software that waits until phase switching is required, and phase switching can be performed very easily and in a short time. Even if there is an abnormality in the step angle at the time of switching, the stepping motor can be driven at a predetermined step angle after phase switching without correcting the timing by correcting it. Therefore, even when an abnormality occurs at the time of switching, vibrations or noises are not generated during the subsequent driving of the motor, and the life of the motor is not shortened.
[0034]
In addition, according to the present invention, even if there is an abnormality that the step angle does not correspond at the time of switching, the speed of the stepping motor can be adjusted by actually smoothly switching the phases. Therefore, even when a program or sequence for controlling the stepping motor is developed, the stepping motor can be controlled practically without any problem even if some bugs or errors are included. Therefore, the time and cost for developing a program or sequence can be saved, and the development time and cost of a device such as a printer using a stepping motor can be reduced.
[0035]
Further, in the control device and the control method of this example, when there is an abnormality in the step angle during phase switching, it can be stored in a dedicated register. Therefore, when there is an abnormality in the sequence of the entire product, it can be determined whether or not it is caused by switching of the phase excitation mode, and can be used for correcting the error. Furthermore, it is of course possible not to automatically correct the step angle, and it becomes easy to find out whether there is a design abnormality during development.
[0036]
In the above description, the present invention has been described using a four-phase stepping motor as an example of the excitation method 2-2 phase, 1-2 phase, and W1-2 phase. However, the present invention is not limited to such an example. Of course. The present invention can also be applied to an excitation method with a smaller step angle such as the WW1-2 phase.
[0037]
Further, although a 4-bit counter is adopted as the phase excitation counter, it is of course possible to use a 5-bit or more counter. However, in order to cyclically count the 16 states of the W1-2 phase, it is desirable to count the states at the fourth bit from the most significant bit. Therefore, in the W1-2 phase, the processing can be performed as described above by increasing or decreasing the counter by binary “10” and setting the fourth bit as the least significant bit.
[0038]
【The invention's effect】
As described above, in the present invention, when a binary phase excitation counter capable of generating a step angle phase excitation signal is provided and the step angle does not match the excitation method after switching when the excitation method is switched, The phase excitation counter is forcibly corrected to coincide with the excitation method after switching, and then the counter is increased or decreased according to the excitation method after switching. Further, by adopting a binary phase excitation counter, correction can be made by setting a predetermined bit string to 0 from the least significant bit or the least significant bit. Therefore, even when there is an abnormality in which the step angle does not match when switching the excitation method, the stepping motor can be driven smoothly from the nearest appropriate step angle by the excitation method after switching.
[0039]
For this reason, by adopting the stepping motor control device and control method according to the present invention, the stepping motor has a suitable step angle when speed control is performed by switching the excitation method of the stepping motor employed in a printer or the like. No hardware or software to monitor until the value is reached. Then, at the timing of switching, the excitation method can be switched smoothly even when the step angles do not match.
[0040]
Further, by adopting the present invention, it is possible to reduce the development time and cost of a program or sequence for controlling a stepping motor. Further, in the control device and the control method of the present invention, if there is an abnormality in the step angle, it is corrected, so the presence or absence of the abnormality in the step angle can be stored in a register or the like at that timing. Therefore, the information can be effectively utilized as a log when a problem occurs in program development or product.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a control device according to an embodiment of the present invention.
2 is a table showing the relationship between the value of the phase excitation counter shown in FIG. 1 and the excitation method, FIG. 2 (a) is 2-2 phase, FIG. 2 (b) is 1-2 phase, and FIG. 2 (c) shows the W1-2 phase excitation method.
FIG. 3 is a flowchart showing processing in the control device shown in FIG. 1;
[Explanation of symbols]
1 Printer
2 heads
3 Carriage
5 Printing paper
10 Stepping motor
11 Rotor
12 Stator
20 Drive circuit
30 Motor controller
35-phase excitation counter
39 Abnormality monitor register
40 Counter control unit
41 Central control unit
42 Update Department
43 Correction section
44 Abnormal output section

Claims (5)

A control device capable of driving a stepping motor with a plurality of excitation methods,
A binary counter that cyclically counts all step angles with the bit that counts the minimum step angle of the stepping motor as the least significant bit, and a phase excitation counter that can generate a phase excitation signal of the corresponding step angle;
Updating means for increasing or decreasing the value of the phase excitation counter according to the rotation direction and excitation method of the stepping motor;
Determining means for determining whether compatible with excitation method after the value of the phase excitation counter switch when switching the excitation mode,
When the value of the phase excitation counter does not correspond to the excitation method after switching, before updating the phase excitation counter by the updating means, the least significant bit of the phase excitation counter corresponding to the excitation method after switching Or correction means for setting the lowest bit string to 0 ;
A stepping motor control device comprising: an abnormality monitoring unit capable of storing the operation of the phase excitation counter by the correction unit . In Claim 1, the said control apparatus can drive a 4-phase stepping motor by the excitation method of 2-2 phase, 1-2 phase, and W1-2 phase,
The phase excitation counter is 4 bits, and the correction means forcibly sets the least significant bit of the phase excitation counter to 0 when the excitation method after switching is 1-2 phase, and the excitation method after switching is 2- In the case of two phases, the stepping motor control device is characterized in that two bit strings are forcibly set to 0 from the least significant bit of the phase excitation counter. Stepping motor using a phase excitation counter that counts the minimum step angle of the stepping motor as the least significant bit and cyclically counts all step angles, and can generate a phase excitation signal of the corresponding step angle. A control method for driving a motor with a plurality of excitation methods,
An update step of increasing or decreasing the value of the phase excitation counter according to the rotation direction and excitation method of the stepping motor;
A determination step of determining whether compatible with excitation method after the value of the phase excitation counter switch when switching the excitation mode,
When the value of the phase excitation counter does not correspond to the excitation method after switching, the least significant bit or the lower-order bit string of the phase excitation counter corresponding to the excitation method after switching is set to 0 before the update process. A correction process to
A stepping motor control method comprising: an abnormality monitoring step of storing that the phase excitation counter has been operated in the correction step . In Claim 3, the 4-bit stepping motor is driven by the excitation method of 2-2 phase, 1-2 phase and W1-2 phase by the 4-bit phase excitation counter,
In the correction step, when the excitation method after switching is 1-2 phase, the least significant bit of the phase excitation counter is forcibly set to 0, and when the excitation method after switching is 2-2 phase, the phase excitation counter A stepping motor control method characterized in that two bit strings are forcibly set to 0 from the least significant bit.   A printer that drives a carriage or a paper feed mechanism by a stepping motor, comprising the control device according to claim 1.

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