JPS63204420A - Alignment control device - Google Patents

Abstract

PURPOSE:To realize an accurate alignment job of a rotor in the shortest time by controlling a driver circuit based on an angle pulse corresponding to the angle of a code plate synchronous with the rotor and stopping the rotor at its target position. CONSTITUTION:A code plate 21 is revolved in response to the shaft of a step motor 5 having a rotor that is driven by a driver circuit 7. A sensor 22 outputs an angle pulse after detecting the rotational angle of the plate 21. These angle pulses are counted by a control part 15 for recognition of the present position of the rotor. Then, the part 15 commands the generating timing of a drive current pulse to the circuit 7 so that the rotor is stopped at its target position in the shortest time. In such a constitution, even if the changes of the external conditions such as the load fluctuation, the temperature change, etc., occur to the motor 5, can be automatically compensated. Thus, the rotor can always be positioned with high accuracy and in the shortest time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning control device for a step motor used to control movement of various movable parts.

[Conventional technology]

FIG. 5 is a diagram in which a step motor is used in the head moving mechanism of a magnetic disk device.

In the figure, 1 is a magnetic disk, 2 is a magnetic head for recording and reproducing, 3 is a carriage that holds the magnetic head 2 and moves in the radial direction of the magnetic disk l, 5 is a step motor, and 4 is the rotation of the step motor 5. This is a steel band that transmits the information to the carriage 3.

Further, 7 is a driver circuit for passing current through each electromagnetic pole of the step motor 5, 6 is a microprocessor that creates the excitation timing of each electromagnetic pole, and information regarding the excitation timing given to the step motor 5 is stored in an external memory 8 in advance. has been done.

The step motor 5 has a stator disposed around a permanent magnet rotor, and the stator has a large number of electromagnetic poles connected in a ring shape. Pulses of exciting current are applied to each electromagnetic pole at different times to generate a rotating magnetic field, and the rotor is accelerated and rotated by the attractive force (or anti-ta force) of the electromagnets.

Next, the operation will be explained. In FIG. 5, after a command to move the magnetic head 2 is given to a microprocessor 6, the microprocessor 6 moves the magnetic head 2 to a target position.
The number of rotational steps of the step motor 5 corresponding to the moving distance and the pulse timing of the excitation current for acceleration and deceleration are referenced from the external memory 8. Then, the driver 7 is sequentially turned on so as to excite each electromagnetic pole of the step motor 5.

It is turned off to create a rotating magnetic field and rotate the step motor 5. This rotational force moves the carriage 3 and further the magnetic head 2 via the steel band 4. FIG. 6 shows the relationship between the moving speed of the head 2 and time at this time.

The head 2 may pass the target position due to the inertia of the step motor 5 and other horizontal systems of the machine, and then a reverse rotational speed is applied to the step motor 5 for a short period of time to move the target position to the center 7.
0], positioning is performed by damped vibration.

The memory 8 stores the intervals between the pulse trains of the excitation current used during acceleration 9 and deceleration 11, and the excitation timing of the pulse train for suppressing vibration during braking 12. Due to speed fluctuations of the step motor 5 caused by temperature changes, the entry speed during deceleration 11 changes, and the resulting deceleration conditions are not constant.

In particular, reverse excitation damping (the moment the rotor crosses the target position, it excites the electromagnetic pole on the side it has passed and causes it to rotate in the opposite direction) and delay damping (excitation for rotation is applied to the rotor), which is used during braking. In methods such as stopping the rotor one step before reaching the target position, and switching excitation to the electromagnetic pole at the target position the moment the rotor reaches the target position due to inertia, the influence of the speed fluctuations mentioned above is large, and the target position is There have been problems in that alignment takes a long time and sometimes causes vibrations, making accurate alignment impossible and making it difficult to stabilize recording and reproduction.

In addition, the microprogram and excitation timing data in the ROM were manually updated in response to load fluctuations and the like.

This invention was made to solve the above-mentioned problems, and enables stable and reliable positioning at high speed when braking a step motor, regardless of external conditions such as load fluctuations due to aging and temperature changes. The purpose is to obtain a control device.

[Means for solving problems]

In this invention, in a step motor 5 having a rotor 25 rotationally driven by a driver circuit 7, a code plate 21 rotates in synchronization with the rotor 5, and an angle pulse is generated by detecting the rotation angle of this code plate 21. The rotor 25 is provided with a sensor 22 that outputs the angle pulse, and a controller 15 that controls the driver circuit 7 based on the angle pulse to stop the rotor 25 at the target position.

[Effect]

By counting the angle pulses by the control unit 15, the current position of the rotor 25 is uniquely recognized.

The control unit 15, which has received the angle pulse as the position information, instructs the driver circuit 7 to generate a drive current pulse so as to bring the rotor 25 to the target position in the shortest possible time and stop the rotor 25. Therefore, even if there is a load fluctuation on the step motor 5, the rotor 25 can always be accurately positioned in the shortest possible time.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 5 is a step motor, 7 is a driver circuit for passing current through each electromagnetic pole of the step motor 5, 6 is a microprocessor that creates the excitation timing of each electromagnetic pole, and 8 is a memory that stores information regarding the excitation timing. memory. 21 is a code plate with a plurality of marks that rotates in conjunction with the shaft 13 of the step motor 5; 22 is a sensor that detects the marks on the code plate; 23 is the code plate 2;
1 is a counter that counts pulses generated when rotating together with the step motor 5.

This counter 23 is programmable, and the count number at which a carry occurs and the count start timing are set by a counter controller 24. Microprocessor 6, ROM8. The counter 23 and the counter controller 24 constitute the control section 15 as a whole.

Referring to FIG. 4, the internal structure of the step motor 5 will be described. A stator 14 is disposed around a rotor 25 made of a permanent magnet that is rotatable together with a support 13. The stator 14 has a large number of electromagnetic poles 26, 27 connected in a circular ring, and has various types (iH'Js 2 G).

Excitation current pulses are applied to the rotor 27 at different times to generate a rotating magnetic field, and the rotor 25 is accelerated by N-3 electromagnetic attraction (or N-N repulsion) and driven to rotate.

The marks provided on the code plate 22 rotating together with the shaft 13 are shown in FIG. 2. The mark MAL on the code plate 21 corresponds to the point where the electromagnetic pole 27 of the step motor 5 and the rotor 25 coincide, and MA2 is The angular position coincides with the next electromagnetic pole, and the angular position of the next MA3 also coincides with the next electromagnetic pole. Each M
An and MAn+1 (n=1.2...) are divided into several intervals and marks MBI to MB5 are provided between them.

These marks MAI, MA2. ...and MBI
.

MB2...MB5 consists of thin wire-shaped permanent magnets arranged at predetermined angles in the radial direction of the code plate 21, and the sensor 22 electromagnetically senses the approach of these thin wire magnets and generates a corresponding angular pulse. Output. Mark MAn is Mark MBn
More ferromagnetic, higher output pulse height, electromagnetic pole 25.2
I'm trying to figure out the location of 6th mag.

While the step motor 5 rotates one step between adjacent electromagnetic poles, several angle pulses (five in the example shown) are generated. FIG. 3 shows how this angular pulse is generated. Fourth
In the figure, when the rotor 25 approaches the electromagnetic pole 27 of the stator and the angle between the two is △Q, the angle pulse of MAI is detected at △Q=O, and on the other hand, the counter 23 counts the pulses corresponding to MBI to MB5. By doing so, the magnitude of ΔQ can be detected.

Next, the operation will be explained.

When braking the rotor 25, which has been rotating from the electromagnetic pole 26 side of the stator toward the electromagnetic pole 27 in FIG. When the rotor 25 is pulled towards the rotor 25, the rotor 25 passes through the electromagnetic pole 27 due to inertia,
An angle ΔQ is created between and the electromagnetic pole 27. In order to return the rotor 25 to the electromagnetic pole 27, and to control the overshoot of the rotor 25 due to this inertia, it is effective to excite the electromagnetic pole 27 of the stator again for a certain period of time Δt (reverse excitation). It is.

It is important to optimize the relationship between the timing of applying this reverse excitation current pulse and ΔQ. The timing for applying this reverse excitation current pulse is given to the microprocessor 6 as a carry of the counter 23, and the setting of ΔQ can be set in the counter 23 by the counter control 24. Therefore, when the rotor 25 passes the target position and the electromagnetic pole 27 at what angle, that is, at what number of low pulses (angle pulses) MBn from the high pulses (angle pulses) of the mark MAI on the code plate 21, reverse excitation is performed. The microprocessor 6 determines whether to start when the carry signal of the counter 23 is a high pulse of MAL or a low pulse of MBI, and is set via the counter control 24.

In this way, even if there are load fluctuations due to aging of the moving mechanism system including the step motor, or fluctuations in the characteristics of the step motor due to temperature changes, these fluctuations are automatically compensated for and the stopping position is always accurate. It becomes possible to match.

Note that although a microprocessor was used in the above embodiment,
A control pulse for the step motor may be generated by a simple timing generation circuit, and the control pulse is not limited to reverse excitation, but various braking pulses can be considered.

Furthermore, although a magnetic disk device is used in this explanation, it is also possible to apply the present invention to a control mechanism using a step motor.

〔Effect of the invention〕

As explained above, according to the present invention, in a step motor having a rotor that is rotationally driven by a driver circuit, a code plate that rotates in synchronization with the rotor and a rotation angle of this code plate are detected and the angle is A sensor that outputs pulses and a control unit that controls a driver circuit based on the angle pulses to stop the rotor at the target position are provided to control the timing of the drive current pulses given to the step motor from the driver circuit. The control system automatically compensates for changes in external conditions such as aging and temperature changes in the load attached to the step motor and the series of movable systems. Positioning control can be performed.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the alignment control device of the present invention, and FIG.
The figure is a partial plan view of the code plate, Figure 3 is a timing chart of angle pulses, Figure 4 is a plan view of the main parts inside the step motor, and Figure 5 is a head mechanism using a conventional step motor. The overall configuration diagram, FIG. 6, is a braking characteristic diagram of a conventional step motor. 5...Step motor, 6...Microprocessor, 7...Driver circuit, 8...
...ROM, 15...Control unit, 21...
...Code board, 22...Sensor, 23...
...Counter, 24...Counter controller, MAn, MBn...Mark. Agent Daikichi Masuo (and 2 others) Male 1 illustration Hondanohashira I-sha Kyokugo 1] Den Pu ・23

Claims (1)

[Claims] A step motor having a rotor rotationally driven by a driver circuit includes a code plate that rotates in synchronization with the rotor, a sensor that detects the rotation angle of the code plate and outputs an angle pulse, and a sensor that detects the rotation angle of the code plate and outputs an angle pulse. and a control section that controls the driver circuit based on the target position and stops the rotor at a target position.