JP2006126485A - Electromagnetic actuator and optical device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic actuator having a self-holding function for accurately positioning a finely movable element, and to provide an optical device using the electromagnetic actuator. <P>SOLUTION: A permanent magnet movable part 1 is so driven as to come into contact with a yoke 6 by using two coils 8 and 9, then a magnetic saturation takes place in a yoke hole 7 part, strong magnetic attraction force is applied on a movable magnetic material 10 by a resulted leaked magnetic flux, and a movable mirror 11 is driven toward the yoke 5 side. Further, the magnetic attraction force acting on the movable magnetic material 10 is released by driving the permanent magnet movable part 1 toward the yoke 6 side, thus the movable mirror part 11 is separated by the restoring force of a flexible part 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic actuator having a self-holding function and an optical device using the same.

In recent years, a technique called a micro electro mechanical system (hereinafter abbreviated as MEMS) realized by applying a semiconductor fine processing technique has been actively researched and developed. Although a minute element can be manufactured with high precision by the MEMS technology, when such a minute element is used as an actuator, a structure in which a force acts on the element itself in a non-contact manner is desirable. An example in which such a fine actuator is applied as an optical switch is disclosed (for example, see Patent Document 1).
In this patent, a reflector (mirror) for switching the optical path is formed using MEMS technology (referred to as micromachining technology in Patent Document 1), and a magnetic body and a coil are fixed to form a movable part. is doing. Furthermore, a set of two permanent magnets is arranged so as to sandwich the movable part with respect to the driving direction of the movable part, and the permanent magnets are magnetized in the opposite direction along the driving direction. In this state, the movable part is attracted to one of the permanent magnets, but the position is switched by applying a current to the coil of the movable part. In this patent, since the movable part is self-held by the permanent magnet, it is not necessary to apply a current except when the movable part is switched, and a low current consumption can be realized.
Japanese Patent Laid-Open No. 2001-235690 (page 4-5, FIG. 7-9)

  In the optical switch shown in the conventional example, even when light is reflected by the mirror portion of the movable part, the light is attracted by the permanent magnet and the movable part is in contact with the permanent magnet (or stopper). However, in the case of an optical switch, there is a problem that light loss occurs due to a mirror position or an angle shift with respect to an optical fiber that guides input / output light. The movable part can be processed with high precision by MEMS technology, but the permanent magnet (or stopper) that contacts the movable part must be formed separately from the movable part, and its assembly accuracy is also required. It is very difficult to realize loss.

  Therefore, an object of the present invention is to provide an electromagnetic actuator having a self-holding function capable of positioning a movable part with high accuracy for application to a low-loss optical switch or the like.

  An aspect of the present invention that solves the above problems includes a movable part that is supported by a flexible part and has a magnetic body, a permanent magnet movable part that has a permanent magnet and moves by receiving magnetic force, and the permanent magnet movable part. An at least one coil for driving the magnet, an attraction yoke having an attraction portion for magnetically attracting the movable portion by the magnetic flux of the permanent magnet when the permanent magnet movable portion is in contact with or in close proximity, and the permanent magnet movable portion Has a separation yoke that guides the magnetic flux and separates the movable part from the suction yoke by contacting or approaching, and a cross-sectional area perpendicular to the magnetic flux in the suction part is another part of the suction yoke. The electromagnetic actuator is smaller than the cross-sectional area perpendicular to the magnetic flux.

  According to the present invention, it is possible to provide an electromagnetic actuator having a self-holding function capable of driving a fine element manufactured by a semiconductor fine processing technique or the like with high accuracy and efficiency.

As described above, a movable part supported by a flexible part and having a magnetic body, a permanent magnet movable part having a permanent magnet and moving by magnetic force, and at least one or more driving the permanent magnet movable part When the permanent magnet movable part is in contact with or in proximity, the attraction yoke having a suction part that magnetically attracts the movable part by the magnetic flux of the permanent magnet, and the permanent magnet movable part is in contact or in proximity. A separation yoke that guides the magnetic flux and separates the movable portion from the suction yoke, and a cross-sectional area perpendicular to the magnetic flux in the suction portion is perpendicular to the magnetic flux in other portions of the suction yoke. The electromagnetic actuator is smaller than the area.
With this structure, it is possible to largely switch the magnetic attractive force acting on the magnetic body provided in the movable part by driving the permanent magnet movable part between the suction yoke and the separation yoke, and as a result, the movable part Can be switched with high accuracy. Further, the suction force acting on the movable part is strengthened by setting the cross-sectional area of the suction part so that the magnetic part is saturated or close to the state when the permanent magnet movable part comes into contact with the suction yoke. It becomes possible.

  The suction part can be realized by forming a circular through hole or a concave shape with respect to the suction yoke.

  Moreover, the permanent magnet movable part can select either linear motion or rotational motion according to the use. Furthermore, it becomes possible to utilize the restoring force by supporting a permanent magnet movable part with a flexible member.

By using the above electromagnetic actuator, a small and low-loss optical device can be configured.
(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view schematically showing a configuration when the electromagnetic actuator of the present invention is applied as an optical switch. The yoke 5 and the yoke 6 are each U-shaped, and the permanent magnet movable part 1 including the permanent magnet 2, the end yoke 3, and the end yoke 4 is located on the open end side. The permanent magnet movable portion 1 can be driven so as to contact the open end of the yoke 5 or the yoke 6. Although not shown in the figure, the permanent magnet movable portion 1 may be supported by a flexible member such as a leaf spring, or a guide or the like for preventing unnecessary operations is provided in the vicinity thereof. Also good. As an example, FIG. 2 shows a schematic diagram when the permanent magnet movable portion 1 is supported by a leaf spring. By joining the leaf spring 13 on the permanent magnet movable portion 1 and fixing the vicinity of the opposite end face, the operation in an unnecessary direction can be restricted and the restoring force of the leaf spring 13 can be used.
A yoke hole 7 is formed on one side of the yoke 6, and the movable magnetic body 10 is positioned above the yoke hole 7. The movable magnetic body 10 is fixed to the movable mirror portion 11 supported by the flexible portion 12. Although the flexible part 12 has a double-supported beam structure with respect to the movable mirror part 11, there is no problem even in a cantilever structure. The flexible portion 12 and the movable mirror portion 11 can be integrally formed with high precision using MEMS technology, and are originally fixed to the same integrally formed substrate at the end of the flexible portion 12. Therefore, it is omitted in FIG. Other members also need to be fixed with a non-magnetic material, but are also omitted. A coil 8 and a coil 9 for driving the permanent magnet movable part 1 are fixed to each yoke. In this case, a coil wire may be directly wound around each yoke, or a coil wound around a bobbin or the like may be inserted into the yoke.

  FIG. 3 is a top view of the electromagnetic actuator in the present embodiment. In addition to the configuration of FIG. 1, FIG. 3 shows an input optical fiber 14 and output optical fibers 15 and 16 for operating as an optical switch. The output optical fiber 15 is arranged so as to be coupled to the optical path 17 when the light emitted from the input optical fiber 14 travels straight. On the other hand, the output optical fiber 16 is arranged so that the light emitted from the input optical fiber 14 is coupled to the optical path 18 reflected by the movable mirror unit 11. With this configuration, it can be seen that the movable mirror unit 11 operates as an optical switch by taking in and out the optical path emitted from the input optical fiber 14. That is, it is possible to operate as an optical switch by applying a magnetic attraction force to the movable magnetic plate 9 fixed to the movable mirror section 11 or canceling the action. Note that this configuration is merely an example, and application to other optical devices is possible by using an optical element such as an optical filter instead of a mirror.

  The operation of the electromagnetic actuator for controlling the magnetic attractive force will be described with reference to FIG. 4A and 4B are side views of the electromagnetic actuator as viewed from the permanent magnet movable part 1 side. In FIG. 4A, the permanent magnet movable part 1 is in contact with the yoke 5 side, but this occurs when the permanent magnet 2 is magnetized in the direction of the arrow shown in the figure. Most of the magnetic flux is guided into the yoke 5 as indicated by broken lines in the figure, and as a result, the permanent magnet movable portion 1 is held by the magnetic attraction force with respect to the yoke 5. In this state, when a current is passed through the coil 8 in the clockwise direction toward the paper surface, a magnetic flux is generated in the direction opposite to the magnetic flux generated by the permanent magnet 2 in the yoke 5. If it becomes stronger than the magnetic flux, a magnetic repulsive force acts between the permanent magnet movable part 1 and the yoke 5. As a result, the permanent magnet movable part 1 moves to the yoke 6 side as shown in FIG. At this time, if a current is applied to the coil 9 in the same direction as the coil 8, a magnetic attractive force acts between the permanent magnet movable portion 1 and the yoke 6, so that the permanent magnet movable portion 1 can be driven more efficiently. Is possible. If the yoke 6 and the permanent magnet movable part 1 are sufficiently close to each other, most of the magnetic flux of the permanent magnet 2 passes through the yoke 6 as shown by the broken line in FIG. Even if it stops, the state can be maintained. In addition, when supporting the permanent magnet movable part 1 with a leaf | plate spring etc. as shown in FIG. 2, it is necessary to consider the restoring force. For example, when the restoring force of the leaf spring acts in the state of FIG. 4A or FIG. 4B, the magnetic attractive force must be designed to be sufficiently stronger than the restoring force. Further, when the permanent magnet movable unit 1 is driven, a force corresponding to the difference between the magnetic attractive force and the restoring force may be generated by the coil.

  Here, the magnetic circuit design important in performing the above operation will be described. When considering downsizing of the actuator, the permanent magnet 2 is preferably a small-sized and strong magnetic force rare earth magnet such as samarium-cobalt or neodymium-iron-boron. In order to efficiently guide the magnetic flux generated by the permanent magnet 2, a soft magnetic material such as permalloy having a high magnetic permeability is used for the yoke 5, the yoke 6 or the end yoke 3 and the end yoke 4. However, attention should be paid to the saturation magnetic flux density as a characteristic of the soft magnetic material. FIG. 5 shows a magnetization curve 20 of 45 permalloy generally used. Basically, as the magnetization of the horizontal axis 21 increases, the magnetic flux density of the vertical axis 22 also increases, but reaches a peak at about 1.4T. This peak value is the saturation magnetic flux density. Here, when the magnetic flux is φ, the magnetic flux density is B, and the yoke cross-sectional area is A, the following equation is established.

φ = B / A
That is, the yoke cross-sectional area needs to be sufficiently large so that this B does not reach the saturation magnetic flux density. If it is 45 permalloy, it is usually desirable to design the magnetic flux density B to be 1.2 T or less. If the sectional area of the yoke 5 is small and magnetic saturation occurs in the state shown in FIG. 4A, the magnetic flux is guided to the yoke 6 side. As a result, the magnetic force between the permanent magnet movable portion 1 and the yoke 5 is increased. As a result, the suction force decreases. Alternatively, the magnetic flux leaks to other parts, which may adversely affect other electronic devices that are close to the actuator.

Next, the magnetic attraction force acting on the movable magnetic plate 9 will be considered. In the state of FIG. 4A, by sufficiently securing the cross-sectional area of the yoke 5, the magnetic flux generated by the permanent magnet 2 hardly flows to the yoke 6 side, and as a result, the magnetic attraction acting on the movable magnetic plate 9. The force also becomes weak, and the state where the movable mirror portion 11 and the yoke 6 are separated is maintained. On the other hand, even in the state of FIG. 4B, it is basically necessary to ensure a sufficient cross-sectional area of the yoke 6. However, in order to generate a strong magnetic attractive force with respect to the movable magnetic plate 9, the yoke hole 7 is provided in a portion of the yoke 6 that contacts the movable magnetic plate 9. In the yoke hole 7, the yoke 6 has a small cross-sectional area, so that the magnetic flux leaks to the movable magnetic plate 9 side, and a strong attractive force can be generated. That is, if the permanent magnet movable part 1 is moved to the yoke 6 side, the movable magnetic plate 9 and the movable mirror part 11 can be driven to the yoke 6 side. If the permanent magnet movable portion 1 is driven from the state shown in FIG. 4B to the state shown in FIG. 4A, the magnetic flux passing through the yoke 6 is greatly reduced as described above. The magnetic attraction force is also reduced, and the movable magnetic body 10 is separated from the yoke 6 by the restoring force of the elastic body 11.
That is, as a result, the yoke 6 is used for attracting the movable part and the yoke 5 is used for opening the movable part, and the position of the movable part can be switched by driving the permanent magnet movable part between the yokes. It has become. In the present embodiment, the cross-sectional area is reduced by the yoke hole 7, but various shapes can be used in consideration of ease of processing. For example, as shown in FIG. 6, the recesses 19 may be provided on both sides of the yoke 6, or a through hole and a recess may be combined.

Considering the above results as the operation of the optical switch, first, in the state of FIG. 4A, since the magnetic attractive force hardly acts on the movable magnetic body 10, the position / angle deviation of the movable mirror portion 11 with respect to the optical path is changed. It can be minimized. Further, in this state, unlike the optical switch mentioned in the conventional example, the movable mirror portion 11 is not in contact with a stopper or the like, so that the high-precision machining that is a feature of the MEMS technology is utilized. On the other hand, in the state of FIG. 4B, the magnetic flux generated in the permanent magnet 2 can be efficiently guided to the movable magnetic body 10 due to the influence of the yoke hole 7, so that the permanent magnet 2 and other magnetic circuits The whole can be downsized. Further, unlike the conventional example, only the movable magnetic body 10 needs to be fixed to the movable mirror portion 11, so that it is possible to reduce the size and weight and to operate at high speed. Furthermore, since the magnetic actuator has a closed magnetic circuit in both cases of FIG. 4A and FIG. 4B, leakage of magnetic flux generated by the permanent magnet 2 can be minimized.
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a perspective view schematically showing a configuration when the electromagnetic actuator of the present invention is applied as an optical switch. FIG. 8 is an exploded view, where (a) is a top view and (b) is a side view. In FIG. 8, the flexible portion 12, the movable mirror portion 11, and the movable magnetic body 10 are omitted for simplification of the drawing. In the second embodiment, the movable mirror unit 11, the movable magnetic body 10, and the flexible unit 12 involved in the optical system of the optical switch have the same configuration as in the first embodiment, and the optical path switching is performed in the same manner. It is possible. Further, the point that the permanent magnet movable portion 1 is composed of the permanent magnet 2 and the yokes 3 and 4 is the same as in the first embodiment.

  The feature of the second embodiment is that the permanent magnet movable portion 1 rotates in contrast to the linear movement between the yokes in the first embodiment. This operation will be described with reference to the side view of FIG. The configuration of the yokes 23 and 24 is such that the open end face is disposed diagonally with respect to the center of the permanent magnet movable part 1 in FIG. 9, and if the permanent magnet movable part 1 rotates counterclockwise, If it rotates clockwise, it contacts the yoke 23. The magnetic circuit is the same as that of the first embodiment, and when the permanent magnet movable portion 1 is in contact with the yoke 23 side, most of the magnetic flux of the permanent magnet 2 passes through the yoke 23, so that it is movable. A magnetic attraction force hardly acts on the magnetic body 10, and the movable mirror portion 11 is held in a state of being separated from the yoke 24 as shown in FIG. On the other hand, as shown in FIG. 9B, when the permanent magnet movable portion 1 is in contact with the yoke 24, most of the magnetic flux passes through the yoke 24 and is in a state where the yoke hole 25 is magnetically saturated or close thereto. Become. As a result, a part of the magnetic flux leaks to the movable magnetic body 10 side, and the magnetic attractive force acts to drive the movable mirror unit 11. Moreover, in order to drive the permanent magnet movable part 1, the current according to the drive direction may be supplied to the coils 26 and 27 as in the first embodiment. If the permanent magnet 2 is magnetized in the direction indicated by the arrow in FIG. 9 and is driven as shown in FIGS. 9 (a) to 9 (b), the coils 26 and 27 are respectively directed toward the page. It is sufficient to apply a sufficient current clockwise.

  In addition, as in the first embodiment, the permanent magnet movable portion 1 can be supported by a flexible member. An example of this is shown in the schematic diagram of FIG. In this case, by joining the hinge spring 28 and the permanent magnet movable part 1 and fixing the fixed part 29, the elastic support part 30 is twisted with the rotational movement of the permanent magnet movable part 1, and a restoring force is generated. . With this restoring force, it is possible to reduce the amount of current applied to the coils 26 and 27 when driving the permanent magnet movable unit 1.

  By adopting the configuration of the second embodiment, even when a linear impact or vibration is applied to the electromagnetic actuator from above, the permanent magnet movable portion 1 is held more than in the first embodiment. Less likely to leave the state. That is, impact resistance and vibration resistance performance are improved. However, the first embodiment has an advantage that the permanent magnet movable portion 1 is in surface contact with the yoke, and thus has a high magnetic efficiency. The structure will be selected.

It is the perspective view which showed typically the structure of the electromagnetic actuator in connection with Embodiment 1 of this invention. It is a block diagram of the permanent magnet movable part and leaf | plate spring in connection with Embodiment 1 of this invention. It is the top view which comprised the electromagnetic actuator in connection with Embodiment 1 of this invention as an optical switch. It is a side view which shows operation | movement of the electromagnetic actuator in connection with Embodiment 1 of this invention. It is a magnetization curve of 45 permalloy. It is a schematic diagram which shows the example of the shape of the movable magnetic body attraction | suction part of a yoke. . It is the perspective view which showed typically the structure of the electromagnetic actuator in connection with Embodiment 2 of this invention. It is the exploded view which showed typically the structure of the electromagnetic actuator in connection with Embodiment 2 of this invention. It is a side view which shows operation | movement of the electromagnetic actuator in connection with Embodiment 2 of this invention. It is a block diagram of the permanent-magnet movable part and hinge spring concerning Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet movable part 2 Permanent magnet 3, 4 End yoke 5, 6 Yoke 7 Yoke hole 8, 9 Coil 10 Movable magnetic plate 11 Movable mirror part 12 Flexible part 13 Plate spring 14 Optical fiber 14 for input
15, 16 Optical fiber for output 17, 18 Optical path 19 Recess 20 Magnetization curve 21 Horizontal axis 22 Vertical axis 23, 24 Yoke 25 Yoke hole 26, 27 Coil 28 Hinge spring 29 Fixing part 30 Elastic support part

Claims (8)

A movable part supported by the flexible part and having a magnetic body;
A permanent magnet movable part that has a permanent magnet and moves by receiving magnetic force;
At least one coil for driving the permanent magnet movable part;
An attraction yoke having an attraction portion for magnetically attracting the movable portion by magnetic flux of the permanent magnet when the permanent magnet movable portion is in contact with or close to the permanent magnet;
The permanent magnet movable part has a separation yoke that guides the magnetic flux and separates the movable part from the attraction yoke when the movable part is in contact with or close to the movable part,
An electromagnetic actuator in which a cross-sectional area perpendicular to the magnetic flux in the attraction portion is smaller than a cross-sectional area orthogonal to the magnetic flux in another part of the attraction yoke.   A cross-sectional area of the attraction part is set so as to become a saturation magnetic flux density or a magnetic flux density close thereto at the attraction part when the permanent magnet movable part contacts or approaches the attraction yoke. The electromagnetic actuator according to claim 1.   The electromagnetic actuator according to claim 1, wherein the suction portion includes a circular through hole provided in the suction yoke.   The electromagnetic actuator according to claim 1, wherein the suction portion includes a concave shape provided in the suction yoke.   The electromagnetic actuator according to claim 1, wherein the permanent magnet movable portion moves linearly.   The electromagnetic actuator according to claim 1, wherein the permanent magnet movable portion is rotationally moved.   The electromagnetic actuator according to claim 5, wherein the permanent magnet movable portion is supported by a flexible member.   The optical device which has an electromagnetic actuator as described in any one of Claim 1 to 7.

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