JPH0746915B2 - Motor drive method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for driving a DC brushless motor used in a serial printer or the like, and more particularly to the origin positioning of the DC brushless motor.

(Prior Art) Conventionally, as a technology in such a field, there is JP-A-63-3148.
Some were described in Japanese Patent No. 8. The configuration will be described below with reference to the drawings. FIG. 2 is a block diagram of a DC brushless motor previously proposed by the present applicant, and FIG.
Is a sectional view of the motor, and FIGS. 2B and 2C are sectional views and plan views of the rotor, respectively. This DC brushless motor includes a stator 1 having a plurality of armature coils 5 provided on a stator yoke, and a disc-shaped magnet 11 in which N and S poles are alternately divided and magnetized in the circumferential direction. And a rotatable rotor 9 provided on a rotor yoke 10 so as to face the rotor. This motor is a DC brushless motor that obtains a rotational force by energizing the armature coil 5 with a predetermined excitation method. The motor 9 is not provided with a position detecting element for detecting the position of the rotor 9, but a slit plate 14 having a plurality of slits for speed detection is provided on the rotor 9, and a frequency proportional to the rotation speed from the slit plate 14 is provided. Two speed detectors (not shown) that obtain the pulse signal of
° The phase is shifted, and at the time of start-up, the origin current is positioned by switching the current supplied to the armature to excite several phases. After that, the position of the rotor 9 is detected by counting the number of pulses output from the speed detector to control the rotation drive. Further, based on the outputs of the two speed detectors and the counting result of the number of pulses thereof, control of switching between forward rotation, reverse rotation and rotation direction is performed. The driving method of the DC brushless motor is such that, at the time of origin positioning, at least before exciting the last phase, the load of the DC brushless motor is removed and the origin positioning is performed.

As a method of removing the load of the DC brushless motor,
For example, when the ink ribbon winding mechanism is a load, there is a method of utilizing the operation of a planetary gear mechanism provided for winding the ribbon in a fixed direction.

Next, the configuration of the planetary gear mechanism will be described with reference to FIG. 3 for explaining the method of removing the load and performing the origin positioning. This planetary gear mechanism is composed of a motor gear 35 attached to a drive shaft (shaft) of a DC brushless motor, three idle gears 36, 37, 38, a planetary gear 39, and a ribbon winding gear 40. .

Here, the operation of the planetary gear mechanism will be described. When the motor gear 35 is rotating counterclockwise in FIG. 3A, the planet gear 39 rotates the ribbon winding gear 40 clockwise through the idle gear 36.

When the motor gear 35 is rotating clockwise in FIG. 3C, the planet gear 39 rotates the ribbon winding gear 40 clockwise through the idle gears 37 and 38.

FIG. 3 (b) shows the transition from (a) to (c). When the motor gear 35 of (a) changes from left rotation to right rotation, the planetary gear 39 changes to the idle gear 36. The ribbon take-up gear 40 is stopped while moving from the meshing position to the meshing position with the idle gear 37. In other words, the DC brushless motor changes the direction of rotation,
While 39 is moving, the ribbon drive load on the motor is “0”.

According to the conventional DC brushless motor driving method, the load of the DC brushless motor is released when the origin is positioned, so that the positioning error due to the load is eliminated and the rotor 9 can always be positioned at the regular stop point.
For this reason, a relatively large torque ripple did not occur in the subsequent motor driving, and good constant speed driving was possible.

(Problems to be Solved by the Invention) However, since it has been found that there are points to be further improved in the conventional DC brushless motor driving method,
Hereinafter, the points to be improved will be described in detail.

Fig. 4 is a simplified circuit diagram of a three-phase motor.
20a is a transistor, 21 to 23 are armature coils, and 24a
Is the positive terminal of the power supply, and 24b is the negative terminal of the power supply.

In the case of two-phase excitation, the directions of the currents flowing in the armature coils 21 to 23 are, in FIG. There are 6 types. To each armature coil 21,22,23 FIG. 5 shows the output torque waveform when a constant current of (1) is applied. In FIG. 5, a, b, c, d, e, f, a'are the intersections of the output torque waveforms and the dotted line P-P ', and A, B, C,
D, E, F, A'are the positions of the rotor 9 that generate the torque at the points a, b, c, d, e, f, a '.

According to the above-mentioned document, the phase driving method for matching the phases of the DC brushless motor is the excitation phase and the excitation time as shown in Table 1 in each of the forward rotation direction and the reverse rotation direction.

The flow chart for matching is as shown in FIG. That is, in the figure, in order to make a forward rotation in the forward rotation direction at the time of starting the motor, in order to clarify the positional relationship between the rotor magnet and the excitation coil, the first to sixth excitations in Table 1 of the combination are performed. , 7th excitation positions the rotor to point A (A ') in Fig. 5,
Furthermore, the rotor is positioned at point E (E ') in FIG. 5 by the ninth excitation (S1). The operation of the DC brushless motor is checked by monitoring the output of a speed detector (not shown) to see if it has rotated during the operation of step 1 (S2). If it is rotating, it moves to the next operation, return (S
Five). If the motor does not rotate, the reverse rotation phase matching is performed in the same manner as in step 1 (S3), and the operation check is performed in the same manner as in step 2 (S4). If the motor is rotating, the process returns to return (S5). If the motor is not rotating, return to step 1 and repeat the same operation. If the carriage collides at the right end, there is no guarantee that the phase can be completely aligned in the forward rotation direction, and it may not move even if a current is applied. Each had an operation check to see if the motor could move. Normally, there is no problem with this flowchart, but if you hold the carriage by hand, or if you keep the stopper of the carriage at the time of packaging, you can move in the forward or reverse rotation direction. No
It enters an infinite loop. In addition, since the motor current value is maximized during phase matching, if a hard alarm circuit such as burnout prevention is included, if the hard alarm circuit operates for a long time in an infinite loop, in the worst case Is power
There was a problem that it also turned off.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to eliminate the problem of entering the infinite loop described above and to provide a driving method that enables safe positioning of the origin of a DC brushless motor in any case.

(Means for Solving the Problems) The present invention provides a rotatable rotor with a slit plate having a plurality of slits for speed detection, and obtains a pulse signal having a frequency proportional to the rotational speed from the slit plate. Two
The two speed detectors are arranged 90 degrees out of phase in electrical angle,
At the time of start-up, the current passing through the armature of the rotor is switched to excite several phases to perform origin positioning, and then the rotor position is detected by counting the number of pulses output by the speed detector. Rotational drive is controlled, and rotation control and rotation direction switching are controlled based on the outputs of the two speed detectors and the results of counting the number of pulses, and at the time of origin positioning, at least the last phase is excited. In the method of driving the motor for locating the origin by removing the load of the motor before the rotation, the step of exciting the rotor in the first rotation direction for locating the origin, and if the rotor does not rotate, the first And a step of exciting the rotor in a second rotation direction opposite to the rotation direction of If you do not both rotating in the rotation direction only, characterized in that it consists of a routine that the error indication of the origin positioning.

(Operation) According to the present invention, since the motor driving method is configured as described above, the rotation operation of the rotor is monitored by the output of the speed detector with respect to the excitation in the first and second rotation directions. If the rotor does not rotate in the first and second rotation directions, the home position positioning error is displayed by the phase alignment error display function, and even if the carriage cannot move due to an external factor, the rotor rotation operation check is infinite. You can avoid entering the loop.

Therefore, it is possible to eliminate the above-mentioned problems, and to provide a driving method capable of safely positioning the origin of the motor in any case.

(Example) Hereinafter, one example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flow chart for explaining the phase matching which is an embodiment of the present invention.

In addition to the conventional phase matching in Fig. 6, as shown in Fig. 1, the motor rotation check is added by the 7th 100 ms excitation and the 9th 150 ms excitation in the forward and reverse rotations of Table 1. (S1, S2, S4, S5). This operation check is judged by monitoring the output of the speed detector,
It is processed. Furthermore, if the result of determination in the normal rotation direction is that the rotation is not possible (NG), the phase immediately shifts to the reverse rotation direction (S1, S2). Even in the reverse rotation direction, it is determined whether or not the same rotation is performed, and among the processing, whether or not the same rotation is performed is determined (S4, S5), and the result is not rotated (N
In the case of G), a routine to display an error indicating a phase matching error has been added (S7).

The judgment process added here is the 7th time and the 9th time. The reason for this is that the phase relationship between the rotor magnet and the exciting coil is unknown at the beginning, as a feature of this phase determination method itself. The first purpose is to position the rotor at point A (A ') in FIG. 5 by driving the excitation phase for the seventh time. Part 7
It is fatal that the rotor cannot move at the first time. The second purpose is to switch the planetary gears by exciting in the opposite direction,
The 9th time when the ribbon load is 0 Is stabilized at the point E (E ') in FIG. It is fatal that the rotor cannot move even at the 9th time, but in reality, the rotor often does not rotate at the 7th time, and the 7th time becomes good and the 9th time does not cause the rotation.

Although the above description has been made in the forward rotation direction, if the rotor is rotating in the reverse rotation operation check (S3, S6), the process proceeds to return (S8). As a result, according to the flowchart of FIG. 1, when the carriage cannot be moved due to the carriage being pressed or the carriage stopper being present, the operation in the forward rotation direction is checked first and the phase in the reverse rotation direction is immediately followed. Then, the routine shifts to a routine for performing an operation check and displaying an error in the reverse rotation direction as well. Furthermore, when hitting the right end in the past, after performing the phase matching process in the forward rotation direction and the operation check after completion, the process went to the phase matching routine in the reverse rotation direction.
Another feature is the speed of the process of shifting to the reverse rotation direction during the forward rotation direction matching.

(Effect of the Invention) As described in detail above, according to the present invention, the conventional DC brushless motor driving method is provided with an operation check function and a phase error display function during phase matching, so that the carriage causes external factors. There is an effect that it is possible to eliminate the situation where the power is turned off due to the worst alarm, such as entering an infinite loop when it cannot move. Furthermore, an additional effect of shortening the processing time can be expected.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining phase matching, which is an embodiment of the present invention, FIG. 2 is a configuration diagram of a DC brushless motor previously proposed by the applicant, and FIG. 3 is for origin positioning by removing a load. Diagram for explaining the method, Fig. 4 shows 3
FIG. 5 is a simplified circuit diagram of the phase motor, FIG. 5 is an output torque waveform diagram of the DC brushless motor, and FIG. 6 is a flowchart for explaining conventional phase matching. 1: Stator, 2: Stator yoke, 5: Armature coil, 9: Rotor, 10: Rotor yoke, 11: Disc magnet, 13: Shaft, 14: Speed detection slit plate, 14a: Slit, 35: Motor gear, 36,37,38: Idle gear, 39: Planetary gear, 40: Ribbon winding gear.

Claims (1)

[Claims] 1. A slit plate having a plurality of slits for speed detection is provided on a rotatable rotor, and two speed detectors for obtaining a pulse signal having a frequency proportional to the rotation speed from the slit plate are connected to an electrical angle. 90 ° out of phase with each other, and at start-up, the current supplied to the armature of the rotor is switched to excite several phases for origin positioning, and then the number of pulses output by the speed detector is counted. Thus, the position of the rotor is detected to control the rotation drive, and the rotation control and the switching of the rotation direction are controlled based on the outputs of the two speed detectors and the counting result of the number of pulses thereof. At the time of positioning, in the method of driving the motor, the load of the motor is removed before the excitation of at least the last phase, and the origin positioning is performed. A routine comprising a step of exciting in a first rotation direction for positioning, and a step of subsequently exciting in a second rotation direction which is a direction opposite to the first rotation direction when the rotor does not rotate. A method for driving a motor, comprising: a routine for displaying an error of origin positioning only when the rotor does not rotate in the first and second rotation directions.