JP2008160900A - Stepping motor controller and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent step-out of a motor by correcting discontinuity of control due to difference in a basic step angle of each of excitation systems switched during driving the motor. <P>SOLUTION: A controller is provided with an excitation switching correcting section 27 for correcting a phase switching step value in switching a phase excitation system, so that even when the phase excitation system is changed, the difference of the basic step angle of each of the excitation systems can be corrected. Alternatively, an interrupt control section 57 is further provided to minimize the occurrence of interruption and the frequency of step value correcting processing in switching the phase excitation system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for controlling a stepping motor that drives a medium and a head in a printing apparatus such as a printer, a copying machine, and a facsimile machine.

  Conventionally, there has been a micro-step driving technique as a technique that can reduce the current ripple of a stepping motor that drives a medium of a printing apparatus and drives a head and can suppress heat generation of the stepping motor. In particular, as a technique for providing a stepping motor driving method that suppresses vibration in a low-frequency acceleration / deceleration region during low-speed rotation and high-speed rotation, there is the following technique (see, for example, Patent Document 1). ).

  First, the configuration and operation of the stepping motor will be described. As shown in FIG. 5, the stepping motor generally has four stators 41 arranged at intervals of 90 degrees and is rotatable inside the stator. A rotor made of a permanent magnet (hereinafter referred to as “rotor 40”) is provided, and a motor output shaft is connected to the rotor 40.

  The same coil is wound around the two opposing stators, and the rotor, which is a permanent magnet, is repelled by the magnetic field generated by passing phase currents of phase A and phase B as electromagnetic currents through the coils. To generate rotating torque.

  The phase current supply pattern includes 1-phase excitation, 1-2-phase excitation, 2-2-phase excitation, etc. 1-phase excitation is a drive method in which excitation is performed sequentially for each phase and rotated at a basic step angle. 2-2 phase excitation is a drive system that always excites two phases (A phase and B phase) adjacent to each other at the same time. 1-2 phase excitation alternates between the 1 phase excitation and 2-2 phase excitation. It is a driving method that repeats.

  As a driving method for preventing vibration and noise during high-speed rotation, there is a micro-step driving method in which the step angle is further finely divided and the rotation is driven smoothly. There are two excitations, and a 2W1-2 excitation method that is two times finer.

  FIG. 8 shows basic steps according to each of the above driving methods. The numbers in the figure represent phase switching step values (hereinafter referred to as “step values”) in which the direction of 45 degrees at the lower right is set to “0” steps. As shown in the figure, the 2-2 phase excitation method is an excitation method for exciting two phases (A phase and B phase) adjacent to each other at the same time, and is expressed as four steps in the 45 degree direction. The

  In the 1-2 phase excitation method, the steps of the 2-2 phase excitation method are divided into two, the W1-2 phase excitation method is further divided into two, and the 2W1-2 phase excitation method is further divided into two steps.

  Therefore, the 2-2 phase excitation method is suitable for control at high speed rotation because the basic step angle is rough but the processing amount of the control unit is small. Conversely, in the 2W1-2 phase excitation method, the processing amount of the control unit is Although the number is increased, fine drive control can be performed, so that vibration can be suppressed.

Taking advantage of the characteristics of each of these excitation methods, 2-2 phase excitation method or 1-2 phase excitation is used at high speed rotation, and W1-2 excitation or 2W1-2 excitation method that is microstep drive is used at low speed rotation. By switching the phase excitation method according to the rotation speed of the motor, vibrations in the low frequency acceleration region and deceleration region are suppressed during low-speed rotation, and insufficient torque is compensated for during high-speed rotation.
JP 9-313000 A

  However, in the conventional control device described above, even when the motor is rotating at a high speed, when performing a process that needs to perform control to reduce vibration as much as possible, 2-2 phase excitation to 1-2 phase is performed. In some cases, switching to excitation is performed, or after the processing, control is performed so as to return from 1-2 phase excitation to 2-2 phase excitation.

  If the excitation method is switched while the motor is rotating as described above, the rotor 40 cannot be continuously driven and controlled due to the difference in the basic step angle of each excitation method, which may cause motor step-out. It was.

  For example, when the motor continues to rotate in the 2-2 phase excitation method, the basic step angle is always “8 steps”, and therefore the position of the previous rotor 40 assumed in the initial step “0” is assumed. Is the upper right position, and the actual rotor position is the same, so continuity is maintained. However, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method as shown in the lower part of FIG. The last step of the 2-2 phase excitation system is “Step 24” (timing Te), and the rotor position assumed in the initial step “0” when switching to the 1-2 phase excitation system is the step. Since it is the right direction which is “28”, the position of the rotor 40 before the assumption is different from the actual rotor position.

  As a result, as shown as (A) in the time chart in the lower part of FIG. 7, the assumed rotor rotation time is half four steps. Conversely, when switching from the 1-2 phase excitation method to the 2-phase excitation method, the rotor position planned in the previous step from the initial position is also different due to the difference in the basic step angle. The rotation of the rotor 40 has progressed too much, and as shown in FIG. 7B, the rotor rotation has progressed by 4 steps, which may cause motor step-out.

  The present invention employs the following configuration in order to solve the above problems. That is, when switching the excitation method in a controller that rotates the stepping motor by sequentially performing phase switching while updating the phase switching step value at predetermined time intervals in a plurality of excitation methods, Excitation switching correction means for correcting the phase switching step value based on the difference between the basic step angles of the front and rear excitation methods is provided.

  According to the present invention described above, according to the stepping motor control device, the excitation switching correction unit that corrects the difference in the basic step angle when switching the excitation method is provided, and the change in the basic step angle due to the switching of the excitation method can be corrected. As a result, the motor does not step out.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element common to drawing.

  The stepping motor control apparatus according to the first embodiment includes an excitation switching correction unit that corrects a step value when the excitation method is switched, so that a change in the basic step angle due to switching of the excitation method can be corrected.

(Constitution)
(Configuration of printing device)
First, the schematic configuration of the printing apparatus according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, the printing apparatus 15 according to the first embodiment includes a CPU 1 that controls the printing apparatus 15, a control unit 2 that performs printing and movement control of each unit such as the head 3 according to a command from the CPU 1, and a control unit. 2 is constituted by a driver 16 that drives each part under the control of 2.

  The CPU 1 is connected with a program ROM 9 for storing a program for executing control, a font ROM 10 for storing font data to be printed, and a RAM 11 for storing data transmitted from a host computer 13 described later. Further, a sensor 12 for detecting the medium position is connected.

  The control unit 2 controls the driver 16 as a driver 16 to drive the head 3 to perform printing, a driver 16 b to drive and control the space motor 6 that moves the head 3, and a feed motor 7 that transports the medium. A driver 16c is connected. The control unit 2 is connected to an LED 4 that informs the user of the state of the printing apparatus 15 and a SW 5 that performs various option designations that can be set by the user. In the following description, the space motor 6 and the driver 16b will be described as an example, but the same applies to the feed motor 7 and the driver 16c.

  The host computer 13 and the printing apparatus 15 are connected by an interface 8 such as IEEE1284, USB, RS232C or the like.

  With the above configuration, when the host computer 13 generates a control command or character data by the printer driver 14 in the host computer 13, it is transferred to the printing apparatus 15 via the interface 8, received, and stored in the RAM 11. The CPU 1 decodes the stored received data, acquires font data from the font ROM 10, creates print data of character and image data, and prints on the medium.

  On the other hand, the control unit 2 uses the sensor 12 that detects the setting value of the SW 5 and the position of the medium to print the generated print data, and the head 3 that prints on the medium and the space for moving the head 3. Printing is performed by controlling the motor 6 and the feed motor 7 for transporting the medium, and the LED 4 informs the user of the state and the like as necessary.

(Control unit firmware function configuration)
Next, firmware function blocks executed by the CPU 1 will be described with reference to the firmware function block diagram of FIG.

  As shown in the figure, the firmware executed by the CPU 1 includes an initialization processing unit 30 that initializes a memory such as the RAM 11 and a device such as the space motor 6 and the LED 4 when the power is turned on, and after the initialization is completed. The host interface transmission / reception processing unit 31 starts data transmission / reception with the host computer 13 and the received data decoding / decompression processing unit 32 decodes the received data and develops it into print data.

  Further, a print control process 33 for performing control for printing the data developed by the decoding process on the medium, a feed motor control process 34 for controlling the conveyance of the medium, and a control for printing the developed print data on the medium. And a space motor control process 36 for performing control for moving the head 3 to perform printing at an arbitrary position on the medium.

(Hardware configuration of control unit)
Next, of the control unit 2 described with reference to FIG. 2, the hardware configuration of the stepping motor control particularly related to the present invention will be described with reference to the hardware configuration diagram of the control unit 2 of FIG.

  As shown in the figure, the control unit 2 of the first embodiment has a timer unit 23 for counting the switching time of the phase switching signal, and the phase value is updated by the output from the timer unit 23. A switching step update unit 24 is included. The CPU 1 is connected with an interrupt signal 29 as an output from the phase switching step update unit 24.

  Furthermore, the control unit 2 of the first embodiment includes a phase switching signal output unit 25a that generates an A-phase and B-phase switching signal from the excitation method set based on a command from the CPU 1 and the updated step value, an A-phase, A current control signal output unit 25b for determining an on-duty time of PWM control corresponding to the current value of the B-phase, and a current control for outputting A-phase and B-phase current control signals corresponding to the on-duty time to the motor driver 16b. Part 26.

  FIG. 4 is a table summarizing the A-phase and B-phase phase switching signals and the A-phase and B-phase current values corresponding to the step values divided into 32 steps. Note that “1” in the phase switching signal indicates that a forward current flows, and “0” indicates that a reverse current flows. The step value is represented by an integer from “0” to “31”, and is incremented by detecting the output pulse from the timer unit 23 by the phase switching step update unit 24. When the step value is “31” Is reset to “0”.

  The switching timing of the phase switching signal and the current control signal differs depending on each excitation method, and the phase switching signal and the output current are applied only when the step value marked with a circle in the “Applied to each excitation method” column, the phase switching signal The phase switching signal and the output current are updated by the output unit 25a and the current control signal output unit 25b.

  For example, in the case of 2-2 phase excitation, since the step values “0”, “8”, “16”, “24” are marked with “、”, the step values “0”, “8”, Only when “16” or “24”, the phase switching signal and the output current are applied.

  When the step value is “0”, the A phase switching signal is “0”, the B phase switching signal is “1”, and both the A phase current value and the B phase current value are “74%”. Therefore, as shown in step “0” of FIG. 6, the current of the stepping motor (FIG. 5) is such that a reverse current of 74% flows in the A phase and a positive current of 74% flows in the B phase. It is controlled by the control unit 26.

  Similarly, since the phase switching signal and the output current are applied only to the step values “0”, “8”, “16”, and “24”, the current flows in each phase as shown by the broken line waveform in FIG. Become.

  In the 2W1-2 phase excitation method, since all the step values are marked with ◯, the phase switching signal and the output current are applied to all the step values.

  For example, when the step value is “1”, the A phase switching signal is “0”, the B phase switching signal is “1”, the A phase current value is “83%”, and the B phase current value is “61%”. As shown in the step value “1” of FIG. 6, 83% of the reverse current flows in the A phase of the stepping motor (FIG. 7), and 61% of the positive current flows in the B phase. Is controlled by the current control unit 26.

  Similarly, since the phase switching signal and the output current are applied to all step values, a current flows through each phase as shown by the solid line waveform in FIG.

  The control unit 2 of the first embodiment further includes an excitation switching correction unit 27 having a function of correcting to an appropriate step value in order to correct a difference in basic step angle when the excitation method is changed. The excitation switching correction unit 27 includes a phase switching timing detection unit 27a that detects whether the excitation method has been switched.

  FIG. 9 is a step value correction table in which correction values for correcting the step value by the excitation switching correction unit 27 are stored for each forward rotation FOW and reverse rotation REV of the motor. For example, the step value correction table may be stored in a memory (not shown) in the excitation switching correction unit 27, or may be stored in a memory of the control unit 2 (not shown).

  The shaded portion in FIG. 9 shows the case where the excitation method has not been switched. In the rotation in the FOW direction, the next step is incremented by 1 and is “+1”, and in the rotation in the REV direction, Since the step is counted down by 1, it is “−1”.

  And, for example, in the rotation in the FOW direction, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method, it is “−3”, so it is corrected to return the step value by 4 steps. Will do.

  Similarly, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method in the rotation in the REV direction, it is “+3”, so that the step value is corrected to advance by 4 steps. become.

(Operation)
With the above configuration, the stepping motor control apparatus according to the first embodiment operates as follows. This operation will be described in detail with reference to the time chart at the time of switching the excitation method in FIG. 7, the operation flowchart in FIG. 10, and the interrupt generation time chart in FIG. 7 is a time chart when the first chart is applied to the upper chart, and a lower chart is a time chart when the conventional technique is applied.

(Timer interrupt generation operation)
First, when the stepping motor control device of the first embodiment receives a stepping motor rotation drive command from the CPU 1, an interrupt signal is generated at predetermined timings as shown in the time chart of FIG.

  That is, a timer value corresponding to the motor rotation speed commanded from the CPU 1 is set as needed, and the timer value is counted down at the rising timing of the clock signal.

  When the timer value becomes “0”, the timer value latch flag is set to “1”, the next timer value is latched (timing Ta), an interrupt signal is generated at the next clock (timing Tb), and the step value is set. Works to update.

  When preparation for updating to the next timer value is completed, the interrupt signal is set to “0”, and the next timer value is determined and set (timing Tc).

  If the timer value to be latched is prepared in advance as shown in the figure, a wasteful processing time such as setting the timer after the update processing time for preparing the next timer value occurs. There is nothing to do.

(Phase switching operation)
The following processing is performed for each timer interrupt described above. This operation will be described with reference to the operation flowchart of FIG. First, it is confirmed whether or not there is a request for switching the excitation method from the CPU 1 (step S31). If there is no request for switching the excitation method, the current excitation method is maintained, so the step value is set to “+1” and step S35 is performed. (Step S32).

  Then, referring to the switching timing and each output value table in FIG. 4 based on the current excitation method and the updated step value, it is determined whether or not to update the phase switching signal and the current value. The process waits until the switching timing is reached (step S35). When the switching timing is reached, the corresponding phase switching signal and current value are set (step S36), and the process is terminated.

  On the other hand, when there is a request for switching the excitation method in step S31, processing similar to that in step S35 is performed as shown in FIG. 4 based on the requested excitation method, that is, the excitation method after switching and the next step value. With reference to the switching timing and each output value table, it is determined whether or not it is time to update the phase switching signal and current value. If it is not the switching timing, the process waits until the switching timing is reached (step S33).

  Then, when the switching timing comes, the step value correction table in FIG. 9 is referred to, and the step value is corrected with the correction value at the corresponding location (step S34). For example, when the step value becomes “0”, there is a rotation command in the FOW direction, and when there is a command to switch from the 2-2 phase excitation method to the 1-2 phase excitation method, “−3” is displayed in the step value correction table. Is stored so that it is corrected by 4 steps, and the step value is corrected to “29”. Since the original value is returned by 4 steps, the step value is “32-4 = 28”, but since it is a rotation in the FOW direction, it is further corrected to “29”.

  In addition, when there is a rotation command in the REV direction and there is a command to switch from the 2-2 phase excitation method to the 1-2 phase excitation method, “+3” is stored in the step value correction table, so substantially four steps. Correct to go forward. In this case as well, since it is supposed to advance four steps ahead, the step value is “0 + 4 = 4”. However, since the rotation is in the REV direction, it is further corrected to “3”. The

  Then, referring to the switching timing and each output value table in FIG. 4 based on the new excitation method and the corrected step value, it is determined whether it is the timing to update the phase switching signal and the current value. Wait until the switching timing is reached. When the switching timing is reached, the corresponding phase switching signal and current value are set ((Steps S35 and S36), and this process is terminated.

  The above operation will be described in more detail with reference to the time chart in the upper part of FIG. In this time chart, after step value “24” driven by the 2-2 phase excitation method (timing Te), the CPU 1 instructs to change from the 2-phase excitation method to the 1-2 phase excitation method. (Timing Tf), then, after the step value “12” (timing Tg), the CPU 1 gives an instruction to change again to the two-phase excitation method (timing Th).

  First, since it is driven by the 2-2 phase excitation method, the phase switching timing is set at step values “8”, “16”, “24”, “0”, and the drive current as shown by the broken line in FIG. The rotor 40 rotates sequentially.

  When the next phase switching timing of the step value “24” is “0” (timing Te), the step value correction table is referred to the step value correction table described above, and the step value is set to “ 29 ". Then, since the step value becomes “0” again after 4 steps (timing Tf), the control is switched to the 1-2 phase excitation method, and the control by the 1-2 phase excitation method is subsequently performed (FIG. 7A). ) Part).

  After switching to 1-2 phase excitation, the phase switching timing is reached at “0” “4” “8” “12” “16” “20” “24” “28”. The drive current is updated while referring to the value table, and the rotor 40 is sequentially rotated as shown in FIG.

  Then, after the step value “12”, when the CPU 1 issues a command to change to the two-phase excitation method again, the step value “16” is the phase switching timing. When the phase switching timing of “16” is reached (timing Tg), the correction value “+5” when switching from 1-2 phase excitation to 2-2 phase excitation is read with reference to the step value correction table. The step value is set to “16 + 5 = 21”, and the process proceeds 4 steps ahead.

  After the elapse of 4 steps, the step value becomes “24” again (timing Th), and the control is switched to the 2-2 phase excitation method. Thereafter, the control by the 2-2 phase excitation method is continued (FIG. 7B). ) Part).

  As described above, even if the excitation method is switched while the motor is rotating, the difference in basic steps between the excitation methods can be corrected, and the assumed position of the rotor 40 can be matched with the actual rotor position. Therefore, continuous and stable motor drive control can be performed.

  In the above description of the embodiment, it has been described that the interrupt to the interrupt signal 29 to the CPU 1 is generated at each step and the step value is corrected as shown in FIG. If an interrupt is generated only at the timing (circled by 4) and the step value is corrected, the load on the CPU 1 can be reduced in addition to the effect of the correction.

  Further, the output to the phase switching signal 25a and the current control unit signal output unit 25b, which are the outputs of the phase switching step update unit 24, and the interrupt signal to the CPU 1 are separated, for example, switching in the 2-2 phase excitation method. If the interrupt value 29 is generated at the timing and the step value is corrected at the timing interpolated by the timing division means (not shown), the load on the CPU 1 can be reduced in addition to the correction effect. it can.

(Effect of Example 1)
According to the stepping motor control device of the first embodiment described above, the excitation switching correction unit that corrects the difference in the basic step angle when the excitation method is switched can be provided, and the discontinuity of the rotor position due to the difference in the basic step angle can be corrected. As a result, the motor does not step out.

  The stepping motor control apparatus according to the second embodiment includes an interrupt control unit 57 that generates a minimum interrupt for performing a step value correction process when changing the excitation method.

(Constitution)
As shown in FIG. 12, the configuration of the stepping motor control apparatus according to the second embodiment has a configuration in which an interrupt control unit 57 is newly provided in addition to the configuration of the first embodiment. Other configurations are the same as the configuration of the stepping motor control apparatus of the first embodiment, and thus detailed description thereof is omitted for the sake of brevity.

  The interrupt control unit 57 controls the interrupt signal 29 from the phase switching step update unit 24 to the CPU 1 and switches the excitation method with the longer interval between the current excitation method and the next excitation method. The interrupt signal 29 is controlled so as to generate an interrupt for performing the step value correction process only in FIG.

  Here, FIG. 15 shows the phase switching timing, the A phase, the B phase switching signal, and the current value with respect to the step value for each excitation method when the rotation direction of the motor is FOW. FIG. 9 is a table in which the correction values in the phase switching step value correction table of FIG.

  That is, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method, correction is made so that four step values are returned as in the phase switching step value correction table of FIG. The step values in the 1-2 phase excitation method corresponding to step 0 of the method are rearranged starting from “28”.

  Similarly, when switching from the 2-2 phase excitation method to the W1-2 phase excitation method, correction is made so that six step values are returned by the phase switching step value correction table, so step 2-2 of the 2-2 phase excitation method is performed. The corresponding step values in the W1-2 phase excitation method are rearranged starting from “26”.

  Similarly, when switching from the 2-2 phase excitation method to the 2W1-2 phase excitation method, correction is made so that seven step values are returned by the phase switching step value correction table, so step 2-2 of the 2-2 phase excitation method is performed. The corresponding step values in the W1-2 phase excitation method are rearranged starting from “25”.

  Even when the motor rotation direction is set to REV, similarly, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method, the step value is corrected so that four step values are advanced by the phase switching step value correction table. The step values in the 1-2 phase excitation method corresponding to step 0 of the 2-2 phase excitation method are rearranged starting from “4”.

  Similarly, when switching from the 2-2 phase excitation method to the W1-2 phase excitation method, the step value is corrected so that six step values are advanced by the phase switching step value correction table. The corresponding step values in the W1-2 phase excitation method are rearranged starting from “6”.

  Similarly, when switching from the 2-2 phase excitation method to the 2W1-2 phase excitation method, correction is made so that seven step values are advanced by the phase switching step value correction table. The corresponding step values in the W1-2 phase excitation method are rearranged starting from “7”.

  When rearranged in this way, for example, when changing from the 2-2 phase excitation method to another phase excitation method and when switching from another phase excitation method to the 2-2 phase excitation method, It can be seen that the correction process only needs to be performed at the phase switching timing.

  That is, when switching from one excitation method to another excitation method, it is understood that the step value should be corrected only at the switching timing of the excitation method with the longer interval between the phase switching timings. Thus, if the interval of the step value correction process is increased, the processing amount of the CPU 1 can be greatly reduced.

(Operation)
The operation of the stepping motor control device according to the second embodiment will be described in detail with reference to the interrupt generation time chart of FIG. 13 and the operation flowchart of FIG. The step value, timer value, timer value (latch), timer value latch flag, counter circuit inside, and clock signal other than the interrupt signal are the same as those in the time chart of FIG.

  In the operation flowchart of FIG. 14, the operations of steps S41 and S42 and steps 44 and S45 are the same as those of steps S31 and S32 and steps 35 and S36 of the first embodiment.

(Timer interrupt generation operation)
First, in the stepping motor control device according to the second embodiment, when a stepping motor rotation drive command is received from the CPU 1, an interrupt signal is sent at every predetermined timing at a clock timing as shown in the time chart of FIG. Generate as.

  That is, a timer value corresponding to the motor rotation speed commanded by the CPU 1 is set as needed, the timer value is counted down at the rising timing of the clock signal, and when the timer value becomes “0”, the latch flag is set to “1” and the next The timer value is latched, the state count flag is generated at the next clock, and the step value is updated. When the preparation for updating to the next timer value is completed, the state count flag is set to “0” and the next timer value is determined.

  Then, based on the state count flag, an excitation method having a longer switching timing between the current excitation method and the next excitation method is selected and generated as an interrupt signal at the phase switching timing of the excitation method.

  For example, when switching from the 2-2 phase excitation method to the 1-2 phase excitation method, or conversely, when switching from the 1-2 phase excitation method to the 2-2 phase excitation method, the 2-2 phase excitation method is phase switched. Since the timing interval is long, an interruption of the interval of the 2-2 phase excitation method shown in FIG. 13 is generated.

  Also, when switching from the W1-2 phase excitation method to the 2W1-2 phase excitation method, or conversely, when switching from the 2W1-2 phase excitation method to the W1-2 phase excitation method, the W1-2 phase excitation method is more phase-switched. Since the timing interval is long, an interval interruption of the W1-2 phase excitation method is generated. If the excitation method is the same, an interrupt is generated at intervals of the excitation method.

(Phase switching operation)
In the stepping motor control apparatus according to the second embodiment, the process of the operation flowchart shown in FIG. 14 is performed for each interrupt described above. That is, first, it is confirmed whether or not there has been a request for switching the excitation method from the CPU 1, and if there is no request for switching the excitation method, the current excitation method is maintained, so the step value is incremented and the process proceeds to step S44 (( Steps S41 and S42).

  Then, referring to the switching timing and each output value table in FIG. 4 based on the current excitation method and the updated step value, it is determined whether or not the timing for updating the phase switching signal and the current value is performed. Waits until the switching timing is reached, and when the switching timing is reached, the corresponding phase switching signal and current value are set (steps S44 and S45), and this process ends.

  On the other hand, when there is a request for switching the excitation method, the phase switching timing confirmation processing as in step S33 of the first embodiment is not performed, and the correction value of the corresponding portion is referred to by referring to the step value correction table of FIG. Correct the step value. For example, when there is a rotation command in the FOW direction, and there is a command to switch from the 2-2 phase excitation method to the 1-2 phase excitation method, “−3” is stored in the step value correction table, so 4 steps. The step value is corrected to return, and the step value is corrected to “29”.

  On the other hand, when there is a rotation command in the REV direction and there is a command to switch from the 2-2 phase excitation method to the 1-2 phase excitation method, “+3” is stored in the step value correction table, so that it is substantially equivalent to 4 steps. Correction is made so as to proceed, and correction is made to “3”.

  Then, based on the new excitation method and the corrected step value, the switching timing and each output value table in FIG. 4 are referred to determine whether or not to update the phase switching signal and the current value. Waits until the switching timing is reached, and when the switching timing is reached, the corresponding phase switching signal and current value are set (steps S44 and S45), and the process is terminated.

(Effect of Example 2)
As described above, according to the stepping motor control apparatus of the second embodiment, when changing the excitation method, the interrupt control unit 57 that generates a minimum interrupt for performing the step value correction process is provided, and the step value correction process is performed. Since it is minimized, in addition to the effects of the first embodiment, the load on the CPU and the like can be greatly reduced.

  The present invention can be widely used in devices using a stepping motor for driving a medium and a head, such as a printing apparatus such as a printer, a copying machine, and a facsimile machine.

FIG. 3 is a configuration diagram of a control unit of the printing apparatus according to the first embodiment. 1 is a configuration diagram of a printing apparatus according to a first embodiment. FIG. 3 is a firmware function block diagram of the printing apparatus according to the first embodiment. 5 is a switching timing and output value table for each step value of the printing apparatus according to the first exemplary embodiment. It is a figure explaining the A phase and B phase of a stepping motor. FIG. 6 is a diagram illustrating current waveforms at each step value of the printing apparatus according to the first exemplary embodiment. It is a time chart figure at the time of the excitation system switching of the prior art and Example 1. FIG. It is a figure explaining each phase excitation system. 3 is a phase switching step value correction table of the printing apparatus according to the first exemplary embodiment. FIG. 5 is an operation flowchart of the printing apparatus according to the first embodiment. FIG. 4 is a time chart diagram of interrupt generation of the printing apparatus according to the first exemplary embodiment. FIG. 6 is a configuration diagram of a control unit of a printing apparatus according to a second embodiment. FIG. 10 is a time chart diagram of interrupt generation of the printing apparatus according to the second embodiment. FIG. 10 is an operation flowchart of the printing apparatus according to the second embodiment. It is the switching timing in each step value of Example 2, and each output value table. It is the switching timing in each step value of Example 2, and each output value table.

Explanation of symbols

1 CPU
2 Control unit 6 Space motor 7 Feed motor 13 Host computer 16b Motor driver unit 23 Timer unit 24 Phase switching step update unit 25a Phase switching output unit 25b Current control signal output unit 26 Current control unit 27 Phase excitation switching correction unit 27a Phase switching timing Detector 29 Interrupt signal 33 Print control process 34 Feed motor control process 35 Head control process 36 Space motor control process 40 Rotor 41 Stator 57 Interrupt control part

Claims (6)

A stepping motor control device for rotating and driving a stepping motor by sequentially performing phase switching while updating a phase switching step value at predetermined time intervals with a plurality of excitation methods,
A stepping motor control device comprising excitation switching correction means for correcting the phase switching step value based on a difference in basic step angle of each excitation method before and after the switching when the excitation method is switched.   2. The phase switching step value is corrected by adding a difference in basic step angle during forward rotation and subtracting a difference in basic step angle during reverse rotation. Stepping motor control device. An interruption control means for setting the predetermined time interval as an interval of phase switching of an excitation method having a large basic step angle of each excitation method before and after switching,
3. The stepping motor control device according to claim 1, wherein the phase switching step value is corrected for each interrupt generated at the interval.   The stepping motor according to any one of claims 1 to 3, wherein the excitation switching correction means corrects the phase switching step value when an excitation method is switched during motor rotation. Control device. A stepping motor control device that controls a stepping motor by switching a plurality of excitation methods,
A stepping unit comprising a phase switching unit that controls the second excitation method based on a current position of the rotor or a moving time of the rotor when switching from the first excitation method to the second excitation method. Motor control device.   A printing apparatus comprising the stepping motor control apparatus according to claim 1.

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