JPH03235696A - Linear motor - Google Patents

Abstract

PURPOSE:To move at a high speed by providing a plurality of coils as a driving coil, and switching the plurality of coils in series or parallel connection according to the moving state of the driving coil. CONSTITUTION:A driving coil 2 has a plurality of coils 3, 4 and is changed-over by change-over means 5, 6 to connect the coils 3, 4 in series or parallel connection according to the moving state of the coil 2. Accordingly, when more thrust is required such as when the coil 2 is accelerated from its stopping state, when it is decelerated from a moving state at a high speed, or when it is operated to position, the coils 3, 4 are connected in series to increase its thrust per unit current, and the coils 3, 4 are connected in parallel in a state that the speed is accelerated to a certain degree or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a linear motor used as an optical head feed motor of an optical disk device.

BACKGROUND OF THE INVENTION In recent years, with the increase in speed of optical disk devices, there has been an increasing demand for linear motors as optical head feed motors.

The linear motor used as the optical head transport motor of this type of conventional optical disk device is shown in 11i! of FIGS. 3 and 4. Changes were common. The configuration will be explained below.

As shown in the figure, a permanent magnet 1o is fixed in a mouth-shaped yoke 11 to form a magnetic circuit. is linked to the magnetic flux of the magnetic circuit. The optical head 13 is connected to the drive coil/l/12 and supported so as to be able to reciprocate together with the drive filter 12. 14 is a disk drive motor. Drive coil 12
is connected to a drive circuit 15, and when the drive circuit 15 causes a predetermined current to flow through the drive coil 12, a thrust is generated to move or position the optical head 13.

The near motor configured as described above has the same characteristics as a so-called DC motor. Tip 9 As shown in Figure 6, as the speed increases, the thrust decreases, and there is a maximum speed VO beyond which the thrust becomes 0 and no further acceleration is possible. In addition, thrust and current are in a proportional relationship, and when a certain current Io is given, thrust F
D is uniquely determined.

Incidentally, a publicly known example of the above-mentioned conventional technology is "Linear Servo Motor and System Design" (written by Manabu Shiraki and Osumi Miyao, published by Izuai Denshi Publishing).

Problems to be Solved by the Invention In such conventional linear motors, the thrust generated and the maximum speed are contradictory, so if you try to obtain thrust by changing the specifications of the drive coil 12, the overcurrent speed will decrease. On the other hand, when trying to achieve maximum speed, the thrust was reduced.

The present invention □ solves the above-mentioned problem, and when a large thrust is required, such as when waiting for start-up or when performing positioning and burying, the thrust is increased to completely shorten the time until the start-up time and stop. Reduce positioning error,
The purpose is to be able to move at maximum speed when high-speed movement is required.

Means for solving all the problems The present invention, d above object? In order to achieve this, the drive coil has a plurality of coils and is equipped with a switching means for switching the plurality of coils to be connected in series or in parallel depending on the state of movement of the drive coil.

Operation The present invention uses the above-mentioned means for solving problems, and when a large amount of thrust is required, such as when the drive coil accelerates from a stopped state, when it decelerates from a state in which it is moving at high speed, or during a positioning operation, a plurality of thrusts are used. By connecting coils in series, it is possible to increase the thrust per unit current, and when the speed increases to a certain level, it is possible to connect multiple coils in parallel to achieve even higher speed movement. Become.

Example 1 Sakashita will explain an example of the present invention with reference to FIG.

As shown in the figure, the permanent magnet 1 has a yoke (
(not shown) to form a magnetic circuit, and a drive coil 2 is provided so as to interlink with the magnetic flux of this magnetic circuit.
This drive coil 2 is supported so as to be movable back and forth in a linear direction. The drive coil 2 has two coils 3.4 which can be switched between a series connection and a parallel connection as shown by means of a relay connection 6.8. The drive coil 2 is connected to a drive circuit 8 which operates in response to a control signal from a control circuit 7, and the control circuit 7 drives a relay 9 which operates a relay contact 6.6.

To explain the operation in the above description, when a predetermined current is passed through the drive circuit 8 and the drive coil 2, as shown in Figure 2, it has the same characteristics as a DC motor, that is, the thrust decreases as the speed increases. have. The characteristic ' shown by a broken line in FIG. 2 is when the coils 3 and 4 are connected in parallel, and the characteristic shown by a solid line is when the coils 3 and 4 are connected in series. Comparing the maximum speeds where the thrust becomes O and cannot be accelerated, the maximum speed qv2 when connected in parallel is twice the maximum speed v1 when connected in series. Also, thrust and current have a proportional relationship, but this coefficient is 2 when connected in series and when connected in parallel.
There is a double difference, and when a certain current IO is passed, the thrust F1 generated when connected in series is 2 yen compared to the thrust F2 generated when connected in parallel.

When the drive coil 2 is in a stopped state, when the control circuit 7 gives a start signal to the drive crossing path 8, the drive circuit 9 starts the drive coil/l.
Start energizing at /2. At this time, the control circuit 7 operates the relay 9 at the same time, so that the relay contact 6.6 is set to Coi/l/3.
4 are connected in series, and the current wire is connected to the drive coil 2.
When ft is given, thrust F1 is generated and acceleration begins, and the acceleration is continued until the speed reaches vl. The thrust F1 at this time is the thrust F2 when the coils 3 and 4 are connected in parallel.
Since 2 is @, the acceleration is large and the speed rise is short. Next, when the speed has risen to a certain level, in other words, when 0.5 seconds have passed after starting, the relay contacts 4 and 5.6 are connected to the coils 3 and 4 in parallel by a signal from the control circuit 7. Switch to the state where At this time,
Although the thrust generated is small, the speed can be accelerated to v2, and the driving carp/l/2 can move at an extremely high speed. Next, to stop the drive coil 2 that is moving at high speed, the control circuit 7 sends a BU]/- key signal to the drive circuit 8, and at the same time operates the relay 9 to close the relay. switches to connect carp/l/3.4 in one row. Therefore, the thrust force in the opposite direction to the moving direction, that is, the braking force, becomes extremely large, and the time required to stop can be shortened. Finally, when the drive coil 2 is in a stopped state and the positioning system is fully executed, the relay contacts 6 and 61 are switched to connect the coils 3 and 4 in one row, increasing the thrust per unit current. , positioning errors can be reduced.

In this way, according to the linear motor of the embodiment of the present invention (for example,
When starting the drive coil 2 that is stopped, when stopping the drive coil 2 that is moving at high speed, or when performing positioning control while in a stopped state, the coils 3 and 4 should be connected in series. : Can generate a larger thrust than C, shorten the start-up time and time to stop, and reduce positioning errors. It can be reduced. When high-speed movement is still required, high-speed movement is possible by connecting coils 3 and 4 in parallel.

In addition, in the above implementation, I used l/-connection 6.6 to switch the connection of coil 3.4, but the same result can be obtained even if a semiconductor switching element such as a thyristor is used. Effects can be obtained.

Effects of the Invention As is clear from the above embodiments, according to the present invention, the drive coil has a plurality of coils 71/, and the plurality of coils can be connected in parallel or connected depending on the moving state of the starting drive coil.・
Since a switching means is provided to switch to the parallel tangent line, the state in which the stopped driving coil A/ is activated, and the condition in which the driving coil A/ is started and the driving coil B when moving at high speed is provided.
When the drive coil is in a stopped state or is in a stopped state and positioning control is being performed, multiple coils can be connected in series to generate a large thrust and shorten the rise time or the time to stop. , it is also possible to reduce positioning errors. Furthermore, in a state where high-speed movement is required, an excellent effect can be obtained in that a plurality of coils can be connected in parallel to enable faster movement.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a linear motor according to an embodiment of the present invention, Fig. 2 is a characteristic diagram of the same linear motor, Fig. 3 is a perspective view of essential parts of an optical disk device equipped with a conventional linear motor, and Fig. 4 is a circuit diagram of a conventional linear motor, and Fig. 6 is a circuit diagram of a conventional linear motor.
It is a characteristic diagram of a near motor. 1...Permanent magnet, 2...Drive coil, 3,
4... Coil, 5, 6... Relay contact (switching means).

Claims (1)

[Claims] A magnetic circuit having a permanent magnet, and a drive coil interlinked with the magnetic flux of the magnetic circuit and supported so as to be movable back and forth in a linear direction, the drive coil having a plurality of coils, and a state of movement of the drive coil. A linear motor comprising a switching means for switching the plurality of coils to be connected in series or in parallel.