JPH0771390B2 - Linear motor device - Google Patents

Description

The present invention relates to a linear motor device used in, for example, a magneto-optical disk device or the like.

<Prior Art> Conventionally, for example, a linear motor is used to drive an optical head or the like incorporated in a magneto-optical disk device. This linear motor drives the movable part (optical head) by the driving force by the electromagnetic force between the driving part yoke and the movable part coil.

However, the conventional linear motor has the following drawbacks.

That is, when the electromagnetic driving force acting on the movable portion coil and the driving portion yoke drives the movable portion in a predetermined linear direction, a reaction force as a reaction thereof acts on the driving portion yoke. Since the drive unit yoke is fixed to the base, the reaction force acting on the drive unit yoke finally acts on the base via the fixed portion between the drive unit yoke and the base to generate a bending moment in the base. As a result, when the base bends, the distance between the head mounted on the movable portion and the disk surface changes subtly, which makes it difficult to keep the distance between the two constant.

Further, due to the distortion of the base, a resonance mode of twisting or bending appears in the base itself. There is also a problem in that the vibration due to the resonance of the base is transmitted to the movable portion to make the motion of the movable portion unstable and reduce the gain margin and the phase margin.

As a result of these problems, there has been a problem that stable recording, reproducing and erasing operations cannot be performed in the entire device.

<Objects of the Invention> The present invention has been made in view of the above problems,
An object of the present invention is to provide a linear motor device having a stable characteristic by suppressing the bending of the base, preventing the occurrence of twisting and bending resonance, and thereby preventing the movable part from being adversely affected.

<Structure of the Invention> In order to achieve the above-mentioned object, the present invention sets the movable part to a predetermined position by an electromagnetic driving force generated between a drive part yoke fixed to the base and a movable part coil provided in the movable part. In a linear motor device that drives in a linear direction, a line of reaction of a reaction force that an electromagnetic driving force generated between the movable coil and the driving yoke reacts with the base is included in the neutral plane of the base. Thus, the linear motor device is characterized in that the drive unit yoke is fixed to the base.

<Operation> When an electromagnetic driving force is generated between the movable coil and the drive yoke, a reaction force that acts on the drive yoke acts. This reaction force is applied to the base via the fixed portion between the drive yoke and the base. To work. The drive yoke is fixed to the base so that the line of action of the reaction force acting on the base is within the neutral plane of the base. With this structure, no bending moment is generated in the base and the base is not distorted.

<Example> Hereinafter, an example of a linear motor device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of a linear motor device according to an embodiment of the present invention, FIG. 2 is a side sectional view taken along the line AA ′ in FIG. 1, and FIG.
Similarly, FIG. 1 shows a sectional view taken along the line BB 'in FIG.

The head 2 mounted and fixed on the movable member 1 shown in FIG. 1 is, for example, an optical head, and is a magneto-optical disk (not shown).
Information is recorded / reproduced / erased on the information medium such as by using laser light. An operating member 3 is connected and fixed to the movable member 1, and the vicinity of the end portion 3-a of the operating member is inserted into a magnetic gap formed by a drive yoke (magnetic body) 7. The drive unit yoke 7 is fixed to the drive unit yoke mounting surface 5-a (see FIG. 3) of the base 5. The base 5 receives a reaction force from the drive unit yoke via the mounting surface 5-a. The line of action of this reaction force is within the mounting surface 5-a, and the drive unit yoke mounting surface 5
Since −a is aligned with the neutral surface 8 of the base, the line of action of the reaction force received by the base lies within the neutral surface 8 of the base.

Here, the “neutral surface” is a term generally used in material mechanics and the like, and means, for example, a surface that does not extend or contract, which is present between a surface that extends when a plate material is bent and a surface that is compressed. In the present invention, attention is paid to the neutral plane existing in the horizontal direction (indicated by reference numeral 8 in FIG. 3). Although there is no neutral plane in the vertical direction as well, bending and twisting in the horizontal direction are negligible compared to the vertical direction and hardly occur, so consider the neutral plane existing in the vertical direction. do not have to.

In the above configuration, when the movable portion coil 4 is energized, a driving force for the movable member 1 is generated by the electromagnetic action of the movable portion coil 4 and the driving portion yoke 7. At the same time, at this time, a reaction force acting as a reaction force of the driving force is applied to the driving portion yoke mounting surface 5
It acts on the base 5 via -a. That is, the line of action of this reaction force lies within the drive unit yoke mounting surface 5-a. Here, the drive unit yoke mounting surface 5-a is the base 5
Since it is coincident with the neutral surface 8 of the base 5, the reaction line of the reaction force acting on the base is within the neutral surface 8 of the base 5, so that the resonance mode of the base 5 caused by the reaction force acting on the base 5 is generated. (Bending or twisting of the base) does not occur.

In the above example, the line of action of the electromagnetic drive force acting between the movable coil 4 and the drive unit yoke 7 is in the same plane as the line of action of the reaction force. A fourth construction in which the line of action of the electromagnetic driving force and the line of action of the reaction force are in different planes so that the relation between the line of action of reaction, the line of action of reaction force and the neutral surface of the base can be easily understood. This relationship will be further explained using the examples of FIGS.

4 is a plan view, FIG. 5 is a sectional view showing an AA cross section in FIG. 4, and FIG. 6 is a sectional view showing a BB cross section in FIG. The parts having the same functions and names as those of the embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals.

In FIGS. 5 and 6, the line indicated by P is the movable coil 4
Is a line of action of an electromagnetic driving force that acts between the actuator and the drive unit yoke 7. Normally, this line of action is determined by the mutual relationship between the drive unit yoke 7 and the movable unit coil 4, and in the case of this example, it is at the position indicated by P in FIG. On the other hand, as shown in FIG. 6, the drive portion yoke 7 is attached to the base 5 by the attachment surface 5-a with screws (of course, it is not necessary to be fixed with “screws”, and adhesion or the like may be used). The drive unit yoke 7 applies a reaction force resulting from an electromagnetic drive force acting between the movable unit coil 4 and the drive unit yoke 7 via the mounting surface 5-a to the base 5.
Will be affected. Therefore, the line of action Q of the reaction force acting on the base 5 is within the mounting surface 5-a. Generally, the line of action P of the electromagnetic driving force acting between the movable coil 4 and the driving yoke 7 and the reaction force exerted on the base 5 depending on the relationship between the mounting positions of the driving yoke 7 and the base 5, the method, and the like. The positional relationship with the line of action Q of is determined. The relationship between the two may be the same as in the above example or may be different as in the present example, and can be relatively freely determined by design.

Now, the neutral surface of the base 5 is located at a portion indicated by reference numeral 8 in FIGS. 5 and 6, and the mounting surface 5-a is made to coincide with the neutral surface 8. As a result, the reaction force received by the base 5 has its line of action Q in the neutral surface 8, and the generation of the resonance mode of the base can be effectively prevented.

Conventionally, the relationship between the line of action of the electromagnetic driving force and the center of gravity of the drive unit, the movable unit, or the mounting position of these has been taken into consideration. It does not generally match the line of action of force)
Since no consideration was given to the positional relationship between the base and the neutral surface of the base, it is not possible to prevent the resonance mode of the base from occurring due to the reaction force of the driving force that acts on the base, and this resonance of the base Vibration is given to the guide that guides the movable member attached to the base, and as a result, the vibration is transmitted to the movable member, and the head mounted / fixed on the movable member also vibrates, which results in stable recording / recording.
The playback / erase operation could not be performed. However, according to the present invention, since the generation of the resonance mode of the base can be prevented, the guide is not vibrated, and as a result, stable recording / reproducing / erasing operations can be performed.

<Effects of the Invention> As described above, according to the present invention, the line of reaction of the reaction force of the electromagnetic driving force generated between the movable coil and the driving yoke to the base is the neutral surface of the base. Since the drive unit yoke is fixed to the base so as to be included therein, a bending moment is not generated in the base due to the reaction force of the electromagnetic driving force, and the base is not bent.
As a result, it is possible to keep the distance between the head mounted on the movable portion and the disk surface constant. Further, since the base is not distorted, no twisting or bending resonance mode appears in the base itself, and no adverse effect is transmitted to the movable portion. Therefore, it is possible to provide a linear motor device capable of providing stable recording, reproducing, and erasing operations with high accuracy and stable operation of the movable portion.

[Brief description of drawings]

1 is a plan view of an embodiment of a linear motor device according to the present invention, FIG. 2 is a side sectional view taken along the line AA 'in FIG. 1, and FIG. 3 is a line BB' in FIG. 4 is a plan view of another embodiment of the linear motor device according to the present invention, FIG. 5 is a cross-sectional view taken along line AA of FIG. 4, and FIG. 6 is B of FIG. −
It is sectional drawing in a B line. 1 ... Movable member, 2 ... Head, 3 ... Actuating member, 3-
a ... Operating member end part, 4 ... Movable part coil, 5 ... Base, 5-a ... Drive part yoke mounting surface, 6 ... Guide, 7 ... Drive part yoke, 8 ... Base neutral surface , P ……
Electromagnetic driving force action line, Q ... Reaction force action line.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-57-110069 (JP, A) JP-A-59-5445 (JP, A) JP-A-58-170354 (JP, A) JP-A-57- 10434 (JP, A) Actual development Sho 57-111088 (JP, U)

Claims (1)

[Claims] 1. A linear motor device for driving the movable part in a predetermined linear direction by an electromagnetic driving force generated between a drive part yoke fixed to a base and a movable part coil provided in the movable part. The drive unit yoke is fixed to the base such that the line of action of the reaction force that the electromagnetic drive force generated between the movable coil and the drive unit yoke reacts on the base is included in the neutral plane of the base. A linear motor device characterized by the following.