JP2018196206A - Stepping motor driving device and stepping motor driving method - Google Patents

Abstract

To provide a stepping motor driving device and a stepping motor driving method capable of realizing high speed driving while suppressing heat generation and vibration of a stepping motor.SOLUTION: A stepping motor driving device 10 includes: a pulse generating section 21 for generating a pulse signal for driving control of a stepping motor 7; and a current control section 22 that changes a first current IA to be supplied to a first coil 13A of the stepping motor 7 and changes a second current IB to be supplied to a second coil 13B of the stepping motor 7 while driving the stepping motor 7 by a basic step angle.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a stepping motor driving apparatus and a stepping motor driving method for driving a stepping motor.

  The stepping motor is a motor suitable for accurate positioning, and is used in, for example, an index table type taping machine or a component inspection machine. In this case, it is conceivable to increase the operating speed of the index table as a method for improving the productivity of the taping machine or the component inspection machine. Since the index table has pockets for conveying parts according to the stepping motor operating angle (basic step angle), the stepper motor operation per unit time can be used to improve the productivity of taping machines and parts inspection machines. It is necessary to increase the frequency with high acceleration / deceleration.

  Therefore, conventionally, the operation frequency of the stepping motor has been increased by increasing the current supplied to the stepping motor (that is, increasing the voltage applied to the stepping motor). However, in this case, heat generation of the stepping motor and vibration (hunting) when the stepping motor stops are problematic. Therefore, it is desirable to provide a new driving method for the stepping motor because the applied voltage cannot be increased without darkness.

  In general, a stepping motor is driven using a technique such as pulse train input or microstepping. In the former method, the acceleration / deceleration of the stepping motor is adjusted according to the pulse input timing, but this timing adjustment is difficult. Further, there is a limit to improving the index feed performance by such timing adjustment. On the other hand, in the latter stage, it takes time to generate a current waveform to be supplied to the stepping motor. Moreover, when performing the two-phase excitation using the former method, the maximum torque cannot be produced by the microstep.

  Examples of conventional stepping motors are disclosed in Patent Documents 1-3. Patent Documents 1 and 2 disclose examples of drive circuits that microstep drive stepping motors used in printers, copiers, and the like. Patent Document 3 discloses an example of a stepping motor control method in which optimum duty ratio data is selected in accordance with motor driving.

Japanese Patent No. 3219601 Japanese Patent No. 3316299 Japanese Patent No. 3368105

  As described above, when the operation frequency is increased by increasing the current supplied to the stepping motor and high-speed driving of the stepping motor is realized, the heat generation and vibration of the stepping motor become a problem.

  Accordingly, an object of the present invention is to provide a stepping motor driving device and a stepping motor driving method capable of realizing high-speed driving while suppressing heat generation and vibration of the stepping motor.

  A stepping motor driving apparatus according to an aspect of the present invention includes a pulse generator that generates a pulse signal for driving control of a stepping motor, and a first coil of the stepping motor while driving the stepping motor by a basic step angle. A current control unit that changes the first current to be supplied and changes the second current to be supplied to the second coil of the stepping motor.

  According to another aspect of the present invention, there is provided a stepping motor driving method in which a step of generating a pulse signal for driving control of a stepping motor is generated and a first stepping motor is driven during driving of the stepping motor by a basic step angle. A current control step of changing a first current supplied to the coil and changing a second current supplied to the second coil of the stepping motor.

  According to the present invention, it is possible to realize high-speed driving while suppressing heat generation and vibration of the stepping motor.

It is a front view which shows the structure of the taping machine of 1st Embodiment. It is a perspective view which shows structures, such as an index table of 1st Embodiment. It is a schematic diagram which shows structures, such as a stepping motor of 1st Embodiment. It is a block diagram showing composition of a stepping motor etc. of a 1st embodiment. It is a perspective view which shows the structure of the index table of 1st Embodiment. It is a graph which shows the time change of the conventional 1st electric current and the 2nd electric current. It is a graph which shows the time change of the 1st electric current and 1st electric current of 1st Embodiment. It is a graph which shows the time change of the 1st electric current and 1st electric current of 1st Embodiment. It is a graph for demonstrating the torque produced | generated with the stepping motor of 1st Embodiment. It is a graph for demonstrating the time change of the displacement angle of the stepping motor in 1st Embodiment. It is a schematic diagram which shows the structural example of the pulse generation part and current control part of 1st Embodiment. It is a graph which shows the time change of the 1st electric current and 2nd electric current of 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a front view showing the configuration of the taping machine of the first embodiment.

  The taping machine of FIG. 1 employs an index method, and includes a tape supply reel holding unit 1, an index table 2, a parts feeder 3, an iron unit 4, a completed tape holding unit 5, and a top tape reel holding unit. 6 is provided. The taping machine of FIG. 1 is used for taping of chip-type electronic components such as capacitors.

  The taping machine transports the tape T1 from the tape supply reel holder 1 via the index table 2 and transports the parts from the parts feeder 3. The parts from the parts feeder 3 are welded to the tape T1 from the index table 2 by the iron part 4. Thereafter, the completed tape T2 obtained from the tape T1 is sent to the completed tape holding unit 5, and the top tape T3 remaining on the tape T1 is sent to the top tape reel holding unit 6.

  FIG. 2 is a perspective view illustrating a configuration of the index table 2 and the like according to the first embodiment.

  The taping machine of the present embodiment includes a stepping motor 7 connected to the index table 2 in addition to the components shown in FIG. When the stepping motor 7 is driven, the index table 2 is thereby driven and the tape T1 is conveyed.

  FIG. 3 is a schematic diagram illustrating a configuration of the stepping motor 7 and the like according to the first embodiment.

  The taping machine of this embodiment includes a coupling 8 and an encoder 9 in addition to the components shown in FIGS. As shown in FIG. 3, the stepping motor 7 includes a rotor 11 and a shaft 12. The shaft 12 is provided so as to penetrate the rotor 11, and the shaft 12 also rotates as the rotor 11 rotates.

  The index table 2 is attached to one end of the shaft 12 via the coupling 8. When the stepping motor 7 is driven, the index table 2 is also rotated by the rotation of the rotor 11 and the shaft 12, whereby the tape T1 is conveyed. The encoder 9 is attached to the other end of the shaft 12 and measures the rotation angle of the shaft 12 and outputs the measurement result.

  FIG. 4 is a block diagram illustrating a configuration of the stepping motor 7 and the like according to the first embodiment.

  The taping machine of this embodiment includes a stepping motor driving device 10 that drives the stepping motor 7 in addition to the components shown in FIGS. 1 to 3. The stepping motor driving apparatus 10 includes a pulse generation unit 21 and a current control unit 22. Furthermore, as shown in FIG. 4, the stepping motor 7 includes a first coil 13A having an A-phase coil portion 13a and an A′-phase coil portion 13a ′, a B-phase coil portion 13b, and a B′-phase coil portion 13b ′. And a second coil 13B.

  The pulse generator 21 generates a pulse signal for driving control of the stepping motor 7. The current control unit 22 controls the first current IA supplied to the first coil 13A and the second current IB supplied to the second coil 13B in synchronization with the pulse signal.

  The first coil 13A includes a terminal P1 on the A phase coil portion 13a side, a terminal P2 on the A ′ phase coil portion 13a ′ side, and a terminal P3 common to the A phase coil portion 13a and the A ′ phase coil portion 13a ′. have. The first current IA includes an A-phase excitation current Ia flowing from the terminal P1 of the A-phase coil portion 13a to the terminal P3 and an A′-phase excitation current Ia ′ flowing from the terminal P2 of the A′-phase coil portion 13a ′ to the terminal P3. Contains.

  The second coil 13B includes a terminal P4 on the B phase coil portion 13b side, a terminal P5 on the B ′ phase coil portion 13b ′ side, and a terminal P6 common to the B phase coil portion 13b and the B ′ phase coil portion 13b ′. have. The second current IB includes a B phase excitation current Ib flowing from the terminal P4 of the B phase coil portion 13b to the terminal P6 and a B ′ phase excitation current Ib ′ flowing from the terminal P5 of the B ′ phase coil portion 13b ′ to the terminal P6. Contains.

  The stepping motor 7 of the present embodiment is driven by two-phase excitation that excites the first and second coils 13A and 13B by two phases. Specifically, the current phases of the first and second currents IA and IB are repeatedly changed in the order of AB phase, A′B phase, A′B ′ phase, and AB ′ phase. During each of these current phases, the stepping motor 7 is driven by the basic step angle. The basic step angle of this embodiment is 1.8 degrees.

  FIG. 5 is a perspective view showing the configuration of the index table 2 of the first embodiment.

  FIG. 5 shows a plurality of pockets H1 provided in the index table 2 at predetermined angles and a plurality of openings H2 provided in the tape T1 at predetermined intervals. In the present embodiment, the predetermined angle is set to 3.6 degrees, which is twice the basic step angle. On the other hand, the predetermined interval is set to the same interval as the interval between the adjacent pockets H1.

  The index table 2 is driven by index feeding by the stepping motor 7. In the index feed, when the stepping motor 7 is in a stationary state, an operation command for operating the stepping motor 7 by a target angle is input to the stepping motor driving device 10. The stepping motor driving device 10 operates the stepping motor 7 by the target angle in accordance with the operation command. The stepping motor 7 returns to a stationary state after rotating by the target angle. In the index feed, the stepping motor 7 rotates by the target angle by repeating such an operation.

  The target angle of this embodiment is 3.6 degrees, which is twice the basic step angle. Therefore, the stepping motor 7 is driven by 3.6 degrees which is twice the basic step angle by one operation command, and the index table 2 is also driven by 3.6 degrees which is one pocket. . In the index feeding, the tape T1 is intermittently conveyed by the predetermined interval by repeating such an operation. Such index feed is called double feed, and the period of one double feed is called one cycle.

  Next, the waveforms of the first and second currents IA and IB of the first embodiment are compared with the waveforms of the conventional first and second currents IA and IB.

  FIG. 6 is a graph showing temporal changes in the conventional first current IA and second current IB.

  In FIG. 6, the first current IA alternately changes between the first value I + and the second value I−. Similarly, the second current IB also alternately changes between the first value I + and the second value I−. Change. Here, the first value I + is a positive value, and the second value I− is a negative value. In FIG. 7, the first value I + is + 2.8A, and the second value I− is −2.8A.

  In the AB phase, the first current IA becomes the A-phase excitation current Ia and the second current IB becomes the B-phase excitation current Ib, so that the first current IA takes the first value I + and the second current IB is also the second current IB. Take 1 value I +.

  In the A′B phase, the first current IA becomes the A ′ phase excitation current Ia ′, the second current IB becomes the B phase excitation current Ib, and the first current IA takes the second value I−, The two currents IB take the first value I +.

  In the A′B ′ phase, the first current IA becomes the A ′ phase excitation current Ia ′, and the second current IB becomes the B ′ phase excitation current Ib ′, so that the first current IA has the second value I−. Thus, the second current IB also takes the second value I−.

  In the AB ′ phase, the first current IA becomes the A-phase excitation current Ia and the second current IB becomes the B′-phase excitation current Ib ′, so that the first current IA takes the first value I + and the second current IB takes a second value I-.

  FIG. 6 shows how the current phases of the first and second currents IA and IB change from the AB phase to the A′B phase and from the A′B phase to the A′B ′ phase. In FIG. 6, the first current IA starts to change in the negative direction from the first value I + at time t and reaches the second value I− at time t + Δt. The symbol Δt represents a delay time until the first current IA changes from the first value I + to the second value I−. Such a delay time Δt also occurs when a change from a phase other than the AB phase to the next phase occurs. When the delay time Δt becomes longer, the problem is that the rise or fall of the torque of the stepping motor 7 is delayed.

  FIG. 7 is a graph showing temporal changes in the first current IA and the second current IB in the first embodiment.

  In FIG. 7, the first current IA changes to the first value I1, the second value I2, and the fourth value I4, and the second current IB changes to the first value I1, the third value I3, and the fourth value I4. To do. Here, the first value I1 and the third value I3 are positive values, and the second value I2 and the fourth value I4 are negative values. However, the absolute value of the first value I1 and the absolute value of the fourth value I4 are set smaller than the absolute value of the second value I2 and the absolute value of the third value I3. In FIG. 7, the first value I1 is + 1A, the second value I2 is -4A, the third value I3 is + 4A, and the fourth value I4 is -1A.

  In the AB phase, the first current IA takes the first value I1, and the second current IB also takes the first value I1. In the A′B phase, the first current IA takes the second value I2, and the second current IB takes the third value I3. In the A′B ′ phase, the first current IA takes a fourth value I4, and the second current IB also takes a fourth value I4. In the AB ′ phase, the first current IA takes the second value I2, and the second current IB takes the third value I3.

  FIG. 7 shows how the current phases of the first and second currents IA and IB change from the AB phase to the A′B phase and from the A′B phase to the A′B ′ phase. In FIG. 7, the first current IA and the second current IB start to change from the first value I1 to the negative direction and the positive direction at time t, respectively, and after the second current IB reaches the third value I3, The current IA reaches the second value I2 at time t + Δt. The symbol Δt represents a delay time until the first current IA changes from the first value I1 to the second value I2. Such a delay time Δt also occurs when a change from a phase other than the AB phase to the next phase occurs.

  Here, in the conventional current waveform (FIG. 6), only one of the first current IA and the second current IB is changed during one phase change. Therefore, the value of the first current IA or the second current IB changes greatly during the phase change. For example, the first current IA changes by −5.8 A when the phase changes from the AB phase, and the second current IB changes by −5.8 A when the phase changes from the A′B phase (see FIG. 6). As a result, the delay time Δt becomes longer, and the rising and falling of the torque of the stepping motor 7 is delayed.

  On the other hand, in the current waveform of this embodiment (FIG. 7), both the first current IA and the second current IB are changed at the time of one phase change. Therefore, it is possible to suppress changes in the first current IA and the second current IB at the time of phase change. For example, the first current IA changes by −5 A and the second current changes by +3 A when the phase changes from the AB phase, and the first current IA changes by +3 A and the second current changes by −5 A when the phase changes from the A′B phase ( (See FIG. 7). Thereby, the delay time Δt can be shortened, and the rising and falling of the torque of the stepping motor 7 can be accelerated.

  In the taping machine of the present embodiment, when the index table 2 is driven by one pocket, the current phases of the first and second currents IA and IB are changed from the AB phase to the A′B via the A′B phase. The stepping motor 7 is driven by twice the basic step angle by changing to the 'phase' or changing from the A'B 'phase to the AB phase via the AB' phase. As a result, when the stepping motor 7 is stationary, the current phase is the AB phase or the A′B ′ phase, and the values of the first current IA and the second current IB are the first value I1 (+ 1A) or the fourth value I4. (-1A).

  Therefore, according to the present embodiment, it is possible to reduce the values of the first current IA and the second current IB in a stationary state, thereby suppressing the heat generation of the stepping motor. In addition, according to the present embodiment, the stepping motor 7 is operated by overdriving the first current IA and the second current IB to the second value I2 (−4A) and the third value I3 (+ 4A), respectively. The operation of the motor 7 can be speeded up. In addition, according to the present embodiment, the torque characteristics of the stepping motor 7 can be improved as described above by reducing the values of the first current IA and the second current IB in the stationary state, and thus the stepping motor can be improved. Vibrations when the motor 7 is stopped can be suppressed. It should be noted that in the present embodiment, even if the first current IA and the second current IB are overdriven as described above, the change in the first current IA and the second current IB during the phase change is small.

  Therefore, according to the present embodiment, it is possible to realize high-speed driving while suppressing heat generation and vibration of the stepping motor 7.

  FIG. 8 is a graph showing temporal changes in the first current IA and the second current IB in the first embodiment.

  FIG. 8 shows a current waveform when driving the index table 2 for four pockets, that is, for four pockets. FIG. 8 further shows a first period R1 corresponding to the AB phase, a second period R2 corresponding to the A′B phase, a third period R3 corresponding to the A′B ′ phase, and a first period corresponding to the AB ′ phase. 4 periods R4.

  In the current waveform of the present embodiment, both the first current IA and the second current IB are changed during one phase change. Specifically, one of the first and second currents IA and IB is changed (that is, increased) in the positive direction, and the other of the first and second currents IA and IB is changed (that is, decreased) in the negative direction. . Here, it should be noted that the increase / decrease in current does not mean that the absolute value of current increases / decreases, but that it means that the value of current including positive / negative signs increases / decreases. . For example, a change in current value from + 1A to -4A corresponds to a decrease in current.

  Here, in the first period R1, the first and second currents IA and IB both change to the first value I1, and specifically, the first current IA changes from the second value I2 to the first value I1. The second current IB increases from the third value I3 to the first value I1 (first operation).

  In the second period R2, the first current IA decreases from the first value I1 to the second value I2, and the second current IB increases from the first value I1 to the third value I3 (second operation).

  Further, in the third period R3, the first and second currents IA and IB both change to the fourth value I4. Specifically, the first current IA increases from the second value I2 to the fourth value I4. Then, the second current IB decreases from the third value I3 to the fourth value I4 (third operation).

  In the fourth period R4, the first current IA decreases from the fourth value I4 to the second value I2, and the second current IB increases from the fourth value I4 to the third value I3 (fourth operation).

  The stepping motor 7 rotates the index table 2 by repeatedly executing the first to fourth operations in order. FIG. 8 shows a state in which index feed of double feed is executed for 4 cycles by repeating the first to fourth operations twice. Each of the first to fourth operations corresponds to the operation of one step of a general stepping motor 7.

  In the second period R2 and the fourth period R4, the first current IA and the second current IB start to change at the same time, and after one of them reaches the second value I2 or the third value I3, the other becomes the second value. The value I2 or the third value I3 has been reached. The time required for this change corresponds to the delay time Δt.

  Further, in the first period R1 and the third period R3, after one of the first current IA and the second current IB starts to change, the other starts to change, and the first current IA and the second current IB are simultaneously set to the first value. I1 or the fourth value I4 has been reached. The time required for this change corresponds to the delay time Δt.

  However, the timing of the start of change and the end of change of the first current IA and the second current IB is not limited to this. For example, the first current IA and the second current IB in the second period R2 and the fourth period R4 may start to change sequentially, or the first current IA and the second current in the first period R1 and the third period R3. The IB may begin to change at the same time.

  FIG. 9 is a graph for explaining the torque generated by the stepping motor 7 of the first embodiment.

  FIG. 9 shows the torque F1 generated in the AB phase and the torque F2 generated in the A′B phase when the basic step angle is 3.6 degrees without applying double feed in the present embodiment. And a torque F3 generated in the A′B ′ phase and a torque F4 generated in the AB ′ phase. FIG. 9 further shows the torque F generated in the A′B phase when the double feed is applied as described above and the basic step angle is set to 1.8 degrees in the present embodiment.

  As shown in FIG. 9, the waveform of the torque F is vertically symmetric, and the rise and fall are steep. Therefore, according to such torque F, it is possible to stop the stepping motor 7 immediately after rotating it by the basic step angle, and to suppress the vibration of the stepping motor 7.

  FIG. 10 is a graph for explaining the change over time of the displacement angle of the stepping motor 7 in the first embodiment.

  Curves D1 and D2 indicate time-dependent changes in the displacement angle when the conventional current waveforms of the first current IA and the second current IB (FIG. 6) are employed. However, in the curve D1, the basic step angle is 3.6 degrees without applying the double feed as in the present embodiment. On the other hand, in the curve D2, double feed is applied as in the present embodiment, and the basic step angle is set to 1.8 degrees. A curve D3 indicates a change with time of the displacement angle when the current waveforms (FIG. 7) of the first current IA and the second current IB of the present embodiment are employed. The basic step angle in the case of the curve D3 is 1.8 degrees.

  Reference numerals t1, t2, and t3 indicate times when the displacement angles of the curves D1, D2, and D3 reach 3.6 degrees, respectively. According to the results of the curves D1 and D2, it can be seen that the operation of the stepping motor 7 can be speeded up by double feeding as in the present embodiment. Furthermore, according to the results of the curves D1 and D3, it can be seen that the operation of the stepping motor 7 can be speeded up to nearly twice the conventional speed by the current waveform (FIG. 7) of the present embodiment.

  FIG. 11 is a schematic diagram illustrating a configuration example of the pulse generator 21 and the current controller 22 according to the first embodiment. FIG. 11A shows a configuration example of the pulse generation unit 21, and FIG. 11B shows a configuration example of the current control unit 22.

  The current control unit 22 includes first to fourth switching elements 31a to 34a and a first current measuring unit 35a for the first coil 13A, and fifth to eighth switching elements 31b to 34b and a second for the second coil 13B. A current measuring unit 35b.

  A pair of first and third switching elements 31a and 33a, a pair of second and fourth switching elements 32a and 34a, a pair of fifth and seventh switching elements 31b and 33b, and a sixth and eighth switching elements 31b , 33b are connected in parallel between the power source and the ground. The first coil 13A is disposed between a node between the first and third switching elements 31a and 33a and a node between the second and fourth switching elements 32a and 34a. The second coil 13B is disposed between a node between the fifth and seventh switching elements 31b and 33b and a node between the sixth and eighth switching elements 32b and 34b.

  The first current IA that has passed through the first coil 13A flows into the first current measurement unit 35a via the third switching element 33a or the fourth switching element 34a, and is measured by the first current measurement unit 35a. The first signal Sa indicating the measurement result of the first current IA is output from the first current measurement unit 35a to the pulse generation unit 21.

  The second current IB that has passed through the second coil 13B flows into the second current measurement unit 35b via the seventh switching element 33b or the eighth switching element 34b, and is measured by the second current measurement unit 35b. The second signal Sb indicating the measurement result of the second current IB is output from the second current measurement unit 35b to the pulse generation unit 21.

  The pulse generator 21 generates pulse signals A1, A2, B1, and B2 according to the first signal Sa, the second signal Sb, the above-described operation command, a signal indicating the measurement result of the encoder 9, and the like. The pulse signal A1 is a signal for controlling the first and fourth switching elements 31a and 34a. The pulse signal A2 is a signal for controlling the second and third switching elements 32a and 33a. The pulse signal B1 is a signal for controlling the fifth and eighth switching elements 31b and 34b. The pulse signal B2 is a signal for controlling the sixth and seventh switching elements 32b and 33b.

  For example, when the first and fourth switching elements 31a and 34a are turned on by the pulse signal A1, a positive current flows through the first coil 13A. Further, when the second and third switching elements 32a and 33a are turned on by the pulse signal A2, a negative current flows through the first coil 13A. When all of the first to fourth switching elements 31a to 34a are on, a current corresponding to the difference between the positive current and the negative current flows through the first coil 13A. The same applies to the second coil 13B. By such control, the current waveform of FIG. 7 can be realized.

  As described above, in the present embodiment, both the first current IA supplied to the first coil 13A and the second current IB supplied to the second coil 13B are driven while the stepping motor 7 is driven by the basic step angle. Change (see FIG. 7). Therefore, according to the present embodiment, it is possible to realize high-speed driving while suppressing heat generation and vibration of the stepping motor 7.

(Second Embodiment)
FIG. 12 is a graph showing temporal changes in the first current IA and the second current IB in the second embodiment. In the present embodiment, the differences from the first embodiment will be mainly described, and a detailed description of common points with the first embodiment will be omitted.

  In the first embodiment, the first and second coils 13A and 13B are driven by two-phase excitation. In the present embodiment, the first and second coils 13A and 13B are driven by one-phase excitation. Yes.

  In FIG. 12, the first current IA changes to the first value I1, the third value I3, and zero, and the second current IB changes to the second value I2, the fourth value I4, and zero. Here, the first value I1 and the fourth value I4 are positive values, and the second value I2 and the third value I3 are negative values. However, the absolute value of the second value I2 and the absolute value of the fourth value I4 are set smaller than the absolute value of the first value I1 and the absolute value of the third value I3. The target angle of this embodiment is also 3.6 degrees, which is twice the basic step angle of 1.8 degrees.

  In the current waveform of the present embodiment, both the first current IA and the second current IB are changed at the time of one phase change, as in the first embodiment.

  For example, in the first period R1, the first current IA increases from zero to the first value I1, and the second current IB decreases from the fourth value I4 to zero (first operation). In the second period R2, the first current IA decreases from the first value I1 to zero, and the second current IB decreases from zero to the second value I2 (second operation).

  Further, in the third period R3, the first current IA decreases from zero to the third value I3, and the second current IB increases from the second value I2 to zero (third operation). In the fourth period R4, the first current IA increases from the third value I3 to zero, and the second current IB increases from zero to the fourth value I4 (fourth operation).

  The stepping motor 7 rotates the index table 2 by repeatedly executing the first to fourth operations in order. FIG. 12 shows a state where index feed of double feed is executed for two cycles by executing the first to fourth operations once. Each of the first to fourth operations corresponds to the operation of one step of a general stepping motor 7.

  Further, the taping machine of the present embodiment shifts from the fourth period R4 to the second period R2 via the first period R1 when driving the index table 2 by one pocket, or from the second period R2 to the second period R2. The process proceeds to the fourth period R4 via the three period R3. As a result, when the stepping motor 7 is stationary, the first current IA becomes zero, and the second current IB becomes the second value I2 or the fourth value I4.

  Therefore, in the present embodiment, the heat generation of the stepping motor 7 can be reduced by setting the second value I2 and the fourth value I4 small. For example, it is desirable that the second value I2 and the fourth value I4 be close to the minimum values for securing the necessary holding torque. Further, by setting the second value I2 and the fourth value I4 small, it becomes possible to increase the acceleration of the stepping motor 7 in the first period R1 and the third period R3.

  Note that the waveform of the second current IB may be replaced with the waveform of the second current IB ′ shown as a modification. The second current IB 'reaches zero after alternately decreasing and increasing in the first period R1. Further, the second current IB 'reaches zero after alternately increasing and decreasing in the third period R3. Thereby, the acceleration / deceleration of the stepping motor 7 can be assisted by the second current IB '.

  As described above, in the present embodiment, both the first current IA supplied to the first coil 13A and the second current IB supplied to the second coil 13B are driven while the stepping motor 7 is driven by the basic step angle. Change (see FIG. 12). Therefore, according to the present embodiment, similarly to the first embodiment, it is possible to realize high-speed driving while suppressing heat generation and vibration of the stepping motor 7.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to these embodiment. These embodiments can be implemented with various modifications without departing from the scope of the present invention. The form which added such a change is also contained in the scope of the present invention.

1: Tape supply reel holding unit 2: Index table 3: Parts feeder 4: Iron unit 5: Finished tape holding unit 6: Top tape reel holding unit 7: Stepping motor 8: Coupling 9: Encoder 10: Stepping motor driving device 11 : Rotor 12: Shaft 13A: 1st coil 13B: 2nd coil 13a: A phase coil part 13a ': A' phase coil part 13b: B phase coil part 13b ': B' phase coil part 21: Pulse generating part 22: Current control unit 31a: first switching element 31b: fifth switching element 32a: second switching element 32b: sixth switching element 33a: third switching element 33b: seventh switching element 34a: fourth switching element 34b: eighth switching Element 35a: first current measurement unit 35b: Second current measuring unit

Claims (9)

A pulse generator for generating a pulse signal for driving control of the stepping motor;
A current control unit that changes a first current supplied to the first coil of the stepping motor and changes a second current supplied to the second coil of the stepping motor while driving the stepping motor by a basic step angle. When,
Stepping motor drive device comprising:   The current control unit changes one of the first and second currents in a positive direction and drives the other of the first and second currents in a negative direction while driving the stepping motor by the basic step angle. The stepping motor driving device according to claim 1, wherein the stepping motor driving device is changed. The current controller is
A first operation for changing the first and second currents to a first value;
A second operation for changing the first current in the negative direction from the first value to the second value and changing the second current in the positive direction from the first value to the third value;
A third operation for changing the first and second currents to a fourth value;
A fourth operation for changing the first current in the negative direction from the fourth value to the second value and changing the second current in the positive direction from the fourth value to the third value;
The stepping motor driving device according to claim 1, wherein the stepping motor is repeatedly executed in order.   4. The stepping motor drive device according to claim 3, wherein an absolute value of the first value and an absolute value of the fourth value are smaller than an absolute value of the second value and an absolute value of the third value. The current controller is
A first operation for changing the first current in a positive direction and changing the second current in a negative direction;
A second operation for changing the first current in a negative direction and changing the second current in a negative direction;
A third operation for changing the first current in the negative direction and changing the second current in the positive direction;
A fourth operation for changing the first current in the positive direction and changing the second current in the positive direction;
The stepping motor driving device according to claim 1, wherein the stepping motor is repeatedly executed in order. The current controller is
A first operation for changing the first current in a positive direction and changing the second current in a negative direction and a positive direction alternately;
A second operation for changing the first current in a negative direction and changing the second current in a negative direction;
A third operation for changing the first current in the negative direction and alternately changing the second current in the positive direction and the negative direction;
A fourth operation for changing the first current in the positive direction and changing the second current in the positive direction;
The stepping motor driving device according to claim 1, wherein the stepping motor is repeatedly executed in order. The stepping motor is connected to an index table in which a plurality of pockets are provided at predetermined angles,
The stepping motor drive according to any one of claims 1 to 6, wherein the current control unit drives the index table by one pocket by driving the stepping motor by twice the basic step angle. apparatus. A pulse generation stage for generating a pulse signal for driving control of the stepping motor;
A current control step of changing a first current supplied to the first coil of the stepping motor and changing a second current supplied to the second coil of the stepping motor while driving the stepping motor by a basic step angle. When,
A stepping motor driving method comprising:   In the current control stage, while driving the stepping motor by the basic step angle, one of the first and second currents is changed in a positive direction, and the other of the first and second currents is changed in a negative direction. The stepping motor driving method according to claim 8, wherein the stepping motor is changed.

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