KR102157589B1 - Apparatus and method for driving a stepping motor - Google Patents

Abstract

An object of the present invention is to provide a stepping motor driving apparatus and a stepping motor driving method capable of achieving high-speed driving while suppressing heat generation and vibration of a stepping motor.
As a means for solving such a problem, the stepping motor driving device 10 includes a pulse generator 21 that generates a pulse signal for driving control of the stepping motor 7 and the stepping motor 7 by a basic step angle. During driving, the first current IA supplied to the first coil 13A of the stepping motor 7 is changed, and the second current IB supplied to the second coil 13B of the stepping motor 7 is changed. ) And a current control unit 22 that changes.

Description

Stepping motor drive device and stepping motor drive method {APPARATUS AND METHOD FOR DRIVING A STEPPING MOTOR}

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

The stepping motor is a motor suitable for precise positioning, and is used, for example, in an index table type taping machine or a parts inspection machine. In this case, as a method for improving the productivity of the taping machine or the parts inspection machine, it is considered to increase the operation speed of the index table. Since the index table has pockets for conveying parts according to the operation angle (basic step angle) of the stepping motor, in order to improve the productivity of the taping machine or parts inspection machine, the operation frequency of the stepping motor per unit time is increased. ) It is necessary to increase it with 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 or vibration (hunting) when the stepping motor is stopped becomes a problem. Therefore, it is desirable to provide a new driving method of the stepping motor, since the applied voltage cannot be unrestrictedly increased.

In general, stepping motors are driven using a method such as pulse train input or microstep. In the former method, the acceleration/deceleration of the stepping motor is adjusted by the timing of inputting the pulse, but this timing is difficult to adjust. In addition, there is a limit to improving the performance of index transfer by such timing adjustment. On the other hand, in the latter step, it takes time to generate the current waveform supplied to the stepping motor. In addition, when performing two-phase excitation using the former method, the maximum torque cannot be generated in the microstep.

Examples of conventional stepping motors are disclosed in Patent Documents 1 to 3 and the like. Patent Literature 1 and Patent Literature 2 disclose examples of drive circuits for microstepping a stepping motor used in a printer, a copy machine, or the like. Patent Document 3 discloses an example of a stepping motor control method in which the optimum duty ratio data is selected according to the driving of the motor.

Japanese Patent No. 32195601 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, heat generation or vibration of the stepping motor becomes a problem.

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

A stepping motor driving apparatus according to an aspect of the present invention includes a pulse generator for generating a pulse signal for driving control of the stepping motor, and supplying the stepping motor to a first coil of the stepping motor while driving the stepping motor by a basic step angle. And a current controller configured to change the first current to be changed and to change the second current supplied to the second coil of the stepping motor.

In addition, a stepping motor driving method according to an aspect of the present invention includes a pulse generating step of generating 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. And a current control step of changing a first current supplied to the stepping motor and changing a second current supplied to the second coil of the stepping motor.

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

1 is a front view showing the configuration of a taping machine according to a first embodiment.
Fig. 2 is a perspective view showing a configuration of an index table and the like according to the first embodiment.
Fig. 3 is a schematic diagram showing a configuration of a stepping motor or the like according to the first embodiment.
Fig. 4 is a block diagram showing a configuration of a stepping motor or the like according to the first embodiment.
Fig. 5 is a perspective view showing the structure of an index table according to the first embodiment.
6 is a graph showing a time change of a conventional first current and a second current.
Fig. 7 is a graph showing changes over time between a first current and a second current in the first embodiment.
Fig. 8 is a graph showing a time change between a first current and a second current in the first embodiment.
9 is a graph for explaining the torque generated by the stepping motor of the first embodiment.
Fig. 10 is a graph for explaining a time change of the displacement angle of the stepping motor in the first embodiment.
Fig. 11 is a schematic diagram showing a configuration example of a pulse generator and a current control unit according to the first embodiment.
Fig. 12 is a graph showing changes over time between a first current and a second current according to the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

1 is a front view showing the configuration of a taping machine according to a first embodiment.

The taping machine of Fig. 1 adopts an index method, and a tape supply reel holding unit 1, an index table 2, a parts feeder 3, an iron unit 4, and a finished tape holding unit ( 5) and a top tape reel holding part 6 are provided. The taping machine of FIG. 1 is used for taping chip-type electronic components such as capacitors, for example.

The taping machine conveys the tape T1 from the tape supply reel holding part 1 through the index table 2 and conveys the parts from the parts feeder 3. Parts from the parts feeder 3 are welded to the tape T1 from the index table 2 by the iron part 4. After that, the finished tape T2 obtained from the tape T1 is sent to the finished tape holding unit 5, and the top tape T3 remaining on the tape T1 is sent to the top tape reel holding unit 6.

2 is a perspective view showing a configuration of the index table 2 and the like of the first embodiment.

The taping machine of this embodiment is provided with a stepping motor 7 connected to the index table 2 in addition to the constituent parts shown in FIG. 1. When the stepping motor 7 is driven, the index table 2 is driven accordingly, and the tape T1 is conveyed.

3 is a schematic diagram showing a configuration of a stepping motor 7 or the like according to the first embodiment.

The taping machine of this embodiment is provided with a coupling 8 and an encoder 9 in addition to the constituent parts shown in Figs. 1 and 2. The stepping motor 7 includes a rotor 11 and a shaft 12 as shown in FIG. 3. The shaft 12 is provided so as to penetrate the rotor 11, and the shaft 12 also rotates when 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 also rotates by rotating the rotor 11 and shaft 12, and the tape T1 is conveyed accordingly. The encoder 9 is attached to the other end of the shaft 12, measures the rotation angle of the shaft 12, and outputs the measurement result.

4 is a block diagram showing a configuration of a stepping motor 7 or the like of the first embodiment.

The taping machine of this embodiment is provided with a stepping motor drive device 10 that drives the stepping motor 7 in addition to the constituent parts shown in FIGS. 1 to 3. The stepping motor drive device 10 includes a pulse generator 21 and a current control unit 22. In addition, 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', and a B-phase coil portion. A second coil 13B having 13b and a B'-phase coil portion 13b' is provided.

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 this pulse signal.

The first coil 13A includes a terminal P1 on the side of the A-phase coil portion 13a, a terminal P2 on the side of the A'-phase coil portion 13a', and the A-phase coil portion 13a and A'phase. It has a terminal P3 common to the coil part 13a'. The first current IA is from the A-phase excitation current Ia flowing from the terminal P1 of the A-phase coil part 13a to the terminal P3 and the terminal P2 of the A'-phase coil part 13a'. It contains the A'phase excitation current Ia' flowing to the terminal P3.

The second coil 13B includes a terminal P4 on the side of the B-phase coil portion 13b, a terminal P5 on the side of the B'-phase coil portion 13b', and the B-phase coil portion 13b and B'phase. It has a terminal P6 common to the coil part 13b'. The second current IB is from the B-phase excitation current Ib flowing from the terminal P4 of the B-phase coil part 13b to the terminal P6 and from the terminal P5 of the B'-phase coil part 13b'. It contains the B'phase excitation current Ib' flowing to the terminal P6.

The stepping motor 7 of this 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 a basic step angle. The basic step angle of this embodiment is 1.8 degrees.

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

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 this 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 be the same as the interval between the adjacent pockets H1.

The index table 2 is driven by an index feed by a stepping motor 7. In the index feed, when the stepping motor 7 is in a stopped state, an operation command for operating the stepping motor 7 by a target angle is input to the stepping motor drive device 10. The stepping motor driving device 10 operates the stepping motor 7 by a target angle according to an operation command. After the stepping motor 7 rotates by a target angle, it becomes a stop state again. In the index feed, the stepping motor 7 rotates by target angle by repeating such an operation.

The objective angle of this embodiment is 3.6 degrees, and this is twice the basic step angle. Accordingly, the stepping motor 7 is driven by 3.6 degrees, which is twice the basic step angle, by one operation command, and accordingly, the index table 2 is also driven by 3.6 degrees, which is equivalent to one pocket. In index transfer, by repeating this operation, the tape T1 is intermittently conveyed at the above predetermined intervals. This index transfer is called double transfer, and the period of double transfer for one time is called 1 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.

6 is a graph showing a time change of a conventional first current IA and a second current IB.

In FIG. 6, the first current IA is alternately changed to a first value (I+) and a second value (I-), and similarly, the second current IB is also a first value (I+) and a second value. It alternately changes to 2 values (I-). 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 becomes a first value ( I+), and the second current IB also takes 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) is A second value (I-) is taken, and the second current (IB) takes a 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) takes a second value (I-), and the second current IB also takes a 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 is zero. It takes one value (I+), and the second current IB takes a second value (I-).

6 shows a state in which the current phases of the first and second currents IA and IB are changed from the AB phase to the A'B phase, and 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 sign Δt represents the delay time until the first current IA changes from the first value I+ to the second value I-. This delay time Δt also occurs similarly when a change from a phase other than the AB phase to the next phase occurs. When the delay time Δt becomes long, it becomes a problem that the rise or fall of the torque of the stepping motor 7 is delayed.

7 is a graph showing a time change of the first current IA and the second current IB in the first embodiment.

In FIG. 7, the first current IA is changed to a first value I1, a second value I2, and a fourth value I4, and the second current IB is a first value I1, It is changed to a third value I3 and a fourth value I4. 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 a first value I1, and the second current IB also takes a first value I1. In the A'B phase, the first current IA takes a second value I2, and the second current IB takes a third value I3. On A'B', 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 a second value I2, and the second current IB takes a third value I3.

Fig. 7 shows a state in which the current phases of the first and second currents IA and IB change from the AB phase to the A'B phase, and 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 minus direction and the plus direction at time t, respectively, and the second current IB becomes third. After reaching the value I3, the first current IA is reaching the second value I2 at time t+Δt. The sign Δt represents the delay time until the first current IA changes from the first value I1 to the second value I2. This delay time Δt also occurs similarly 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 significantly during phase change. For example, when the phase changes from the AB phase, the first current IA changes -5.8A, and when the phase changes from the A'B phase, the second current IB changes -5.8A (Fig. 6 Reference). As a result, the delay time Δt becomes long, and the increase or decrease of the torque of the stepping motor 7 is delayed.

On the other hand, in the current waveform (FIG. 7) of the present embodiment, both the first current IA and the second current IB are changed during one phase change. Therefore, it becomes possible to suppress the change of the first current IA and the second current IB at the time of a phase change small. For example, when the phase changes from the AB phase, the first current (IA) changes -5A, the second current changes +3A, and when the phase changes from the A'B phase, the first current (IA) is +3A. , The second current is changed by -5A (see Fig. 7). Accordingly, it becomes possible to shorten the delay time Δt and to increase or decrease the torque of the stepping motor 7 at high speed.

In addition, in the taping machine of this embodiment, when driving the index table 2 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 phase. The stepping motor 7 is driven by twice the basic step angle by changing to the'B' phase or changing from the A'B' phase through the AB' phase to the AB phase. As a result, when the stepping motor 7 is in a stop state, the current phase becomes the AB phase and the A'B' phase, and the values of the first current IA and the second current IB are the first values I1 ( +1A) becomes the fourth value I4 (-1A).

Accordingly, according to the present embodiment, the values of the first current IA and the second current IB in the stopped state can be reduced, and accordingly, heat generation of the stepping motor can be suppressed. In addition, according to this embodiment, when the stepping motor 7 is operated, the first current IA and the second current IB are respectively set to the second value I2 (-4A) and the third value I3 ( +4A), the operation of the stepping motor 7 can be accelerated. In addition, according to the present embodiment, by reducing the values of the first current IA and the second current IB in the stationary state, the torque characteristics of the stepping motor 7 can be improved as described above, and accordingly Vibration when the stepping motor 7 stops can be suppressed. In this 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 at the time of phase change is small. Be careful.

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

Fig. 8 is a graph showing the time change of the first current IA and the second current IB according to the first embodiment.

Fig. 8 shows the current waveform when driving the index table 2 for 4 cycles, that is, for 4 pockets. Fig. 8 also 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 AB. 'The fourth period R4 corresponding to the phase is shown.

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, IB) changes (i.e., increases) in the positive direction, and the other of the first and second currents (IA, IB) changes (i.e. decreases) in the negative direction. ). Here, it should be noted that the increase or decrease of the current does not mean that the absolute value of the current increases or decreases, but that the value of the current including the positive or negative sign increases or decreases. For example, a change in the 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 are both changed to the first value I1, and specifically, the first current IA is the second value ( It increases from I2) to the first value I1, and the second current IB decreases 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 decreases from the first value I1 to a third value ( It is increasing to I3) (second operation).

Further, in the third period R3, the first and second currents IA and IB are both changed to the fourth value I4, and specifically, the first current IA is the second value ( It increases from I2) to the fourth value I4, and 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 decreases from the fourth value I4 to a third value ( It is increasing to I3) (operation 4).

The stepping motor 7 rotates the index table 2 by repeatedly performing the first to fourth operations in sequence. Fig. 8 shows a state in which the index transfer of double feed is performed for 4 cycles by repeating the first to fourth operations twice. Each of the first to fourth operations corresponds to an operation for one step of the general stepping motor 7.

Further, 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 one of them is the second value I2 or the third After reaching the value I3, the other is reaching the second value I2 or the third value I3. The time required for this change corresponds to the above 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 reaching the first value I1 or the fourth value I4 at the same time. The time required for this change corresponds to the above delay time Δt.

However, the timing at which the first current IA and the second current IB start or end of change 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 in sequence, and the first period R1 and the third The first current IA and the second current IB in the period R3 may start to change simultaneously.

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

9 shows the torque F1 generated on AB, the torque F2 generated on A'B, and A'when the basic step angle is 3.6 degrees without applying double feed in this embodiment. The torque F3 generated on the B'phase and the torque F4 generated on the AB' are shown. 9 also shows the torque F generated on A'B when the basic step angle is 1.8 degrees by applying the double feed as described above 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 this torque F, it becomes possible to quickly stop the stepping motor 7 after rotating it by the basic step angle, or to suppress the vibration of the stepping motor 7.

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

Curves D1 and D2 show changes over time in the displacement angle when the conventional current waveforms (FIG. 6) of the first current IA and the second current IB are employed. However, in the curve D1, the double feed as in the present embodiment is not applied, and the basic step angle is set to 3.6 degrees. 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. Curve D3 shows the time change 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 curve D3 is 1.8 degrees.

Symbols t1, t2, and t3 indicate the time for the displacement angles of the curves D1, D2, and D3 to 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 accelerated by the double feed as in the present embodiment. Further, according to the results of the curves D1 and D3, it can be seen that the operation of the stepping motor 7 can be increased to nearly twice the conventional speed by the current waveform (Fig. 7) of the present embodiment.

11 is a schematic diagram showing a configuration example of the pulse generator 21 and the current control unit 22 according to the first embodiment. Fig. 11A shows an example of the configuration of the pulse generator 21, and Fig. 11B shows an example of the configuration of the current control unit 22.

The current control unit 22 includes first to fourth switching elements 31a to 34a for the first coil 13A, the first current measuring unit 35a, and fifth to eighth for the second coil 13B. It includes switching elements 31b to 34b and a second current measurement 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 the pair of the eighth switching elements 31b and 33b are connected in parallel between the power supply 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 the first current measurement unit ( It is measured in 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 measuring unit 35b via the seventh switching element 33b or the eighth switching element 34b, and flows into the second current measuring unit ( It is measured in 35b). The second signal Sb representing 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. Occurs. 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 turned on, a current corresponding to the difference between the positive current and the negative current flows through the first coil 13A. This is also the same for the second coil 13B. With this control, the current waveform in Fig. 7 can be realized.

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

(Second embodiment)

Fig. 12 is a graph showing changes in time of the first current IA and the second current IB according to the second embodiment. In this embodiment, differences from the first embodiment will be mainly described, and detailed descriptions of points in common 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, whereas in this embodiment, the first and second coils 13A and 13B are driven by one-phase excitation. Are doing.

In FIG. 12, the first current IA is changed to a first value I1, a third value I3, and zero, and the second current IB is a second value I2 and a 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 to be 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 3.6 degrees, which is twice the basic step angle of 1.8 degrees.

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

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 (second 3 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 (operation 4 ).

The stepping motor 7 rotates the index table 2 by repeatedly performing the first to fourth operations in sequence. Fig. 12 shows a state in which the index transfer of double feed is performed for two cycles by executing the first to fourth operations once. Each of the first to fourth operations corresponds to an operation for one step of the general stepping motor 7.

In addition, when driving the index table 2 by one pocket, the taping machine of this embodiment shifts from the fourth period R4 to the second period R2 through the first period R1, or The transition from the period R2 to the fourth period R4 through the third period R3. As a result, when the stepping motor 7 is in a stopped state, the first current IA becomes zero, and the second current IB becomes the second value I2 and the fourth value I4.

Therefore, in this embodiment, it becomes possible to reduce heat generation of the stepping motor 7 by setting the second value I2 and the fourth value I4 to be small. It is preferable that the second value I2 and the fourth value I4 be close to a minimum value for securing the required torque for holding, for example. 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 or the third period R3.

Further, the waveform of the second current IB may be replaced with the waveform of the second current IB' shown as a modified example. The second current IB' is alternately decreased and increased in the first period R1, and then reaches zero. Further, the second current IB' has increased and decreased alternately in the third period R3, and then reaches zero. Accordingly, it becomes possible to assist the acceleration/deceleration of the stepping motor 7 by the second current IB'.

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

As mentioned above, although the embodiment of this invention was demonstrated, this invention is not limited only to these embodiment. These embodiments can be implemented by adding various changes within a range not departing from the gist of the present invention. In the scope of the present invention, the form to which such changes were added is also included.

1: Tape supply reel holding unit 2: Index table
3: Part feeder 4: Iron part
5: Finished tape holding unit 6: Top tape reel holding unit
7: stepping motor 8: coupling
9: encoder 10: stepping motor drive device
11: rotor 12: shaft
13A: first coil 13B: second coil
13a: A-phase coil part 13a': A'-phase coil part
13b: B-phase coil portion 13b': B'-phase coil portion
21: pulse generator 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 measuring unit 35b: second current measuring unit

Claims (9)

A pulse generator for generating a pulse signal for driving control of a two-phase stepping motor having a first coil having an A phase and a second coil having a B phase,
While driving the stepping motor by a basic step angle, a current controller that changes a first current supplied to the first coil of the stepping motor and also changes a second current supplied to the second coil of the stepping motor
Stepping motor drive device comprising a. The method of claim 1,
The current controller changes one of the first and second currents in a positive direction while driving the stepping motor by the basic step angle, and changes the other of the first and second currents in a negative direction. Letting, stepping motor drive device. The method of claim 1,
The current control unit,
A first operation of changing the first and second currents to a first value,
A second operation of changing the first current from the first value to a second value in a negative direction and changing the second current from the first value to a third value in a positive direction,
A third operation of changing the first and second currents to a fourth value,
A fourth operation of changing the first current from the fourth value to the second value in a negative direction and changing the second current from the fourth value to the third value in a positive direction
Stepping motor drive device that repeatedly executes in sequence. The method of claim 3,
The absolute value of the first value and the absolute value of the fourth value are smaller than the absolute value of the second value and the absolute value of the third value. The method of claim 1,
The current control unit,
A first operation of changing the first current in a positive direction and changing the second current in a negative direction,
A second operation of changing the first current in a negative direction and changing the second current in a negative direction,
A third operation of changing the first current in a negative direction and changing the second current in a positive direction,
A fourth operation of changing the first current in the positive direction and changing the second current in the positive direction
Stepping motor drive device that repeatedly executes in sequence. The method of claim 1,
The current control unit,
A first operation of changing the first current in a positive direction and alternately changing the second current in a negative direction and a positive direction,
A second operation of changing the first current in a negative direction and changing the second current in a negative direction,
A third operation of changing the first current in a negative direction and alternately changing the second current in a positive direction and a negative direction,
A fourth operation of changing the first current in the positive direction and changing the second current in the positive direction
Stepping motor drive device that repeatedly executes in sequence. The method of claim 1,
The stepping motor is connected to an index table in which a plurality of pockets are provided at predetermined angles,
The current control unit drives the stepping motor twice the basic step angle to drive the index table by one pocket. A pulse generation step of generating a pulse signal for driving control of a two-phase stepping motor having a first coil having an A phase and a second coil having a B phase,
Current control for changing a first current supplied to the first coil of the stepping motor and also changing a second current supplied to the second coil of the stepping motor while driving the stepping motor by a basic step angle step
Stepping motor driving method comprising a. The method of claim 8,
In the current control step, 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. Changing, stepping motor driving method.

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