JP3009560U - Electromagnetic drive type magneto-optical device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the size of the device, drive it with a small amount of power, and shorten the response time. A gap 22 is provided in a magnetic circuit formed by the magnetic yoke 20, and the magneto-optical element 2 is placed in the gap.
4 is arranged, and the coil 26 is provided so as to surround the gap. Two magnetic yokes having the same shape are arranged to face each other. The magnetic yoke is, for example, an E type having a central leg shorter than both side legs, and has a structure in which a light beam passage hole penetrates the central leg. The bobbin is a combination of two half bobbins integrally formed with a cylindrical portion fitted to the magnetic yoke and a flange portion located at one end of the bobbin with an element holder interposed therebetween. It is preferable to form stepped portions on both sides of which the bobbin cylindrical portion fits, and attach the magneto-optical element to at least one surface thereof.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magneto-optical device driven by an electromagnet method. More specifically, the magneto-optical element is arranged in a gap formed in a magnetic circuit, and a coil is provided around the gap to apply a magnetic field. The present invention relates to a drive type magneto-optical device. This device is useful, for example, as an optical switch or a magnetic field sensor.

[0002]

[Prior art]

 In fields such as optical communication, optical measurement, and optical recording, a device that magnetizes a magneto-optical element with an electromagnet is used. Typical examples are optical switches and magnetic field sensors. In such a device, a gap is provided in a part of the magnetic yoke, a magneto-optical element is inserted in the gap, a coil is provided in the other part of the magnetic yoke, and the current of the winding is controlled. I am configuring.

Specifically, as shown in FIG. 9A, for example, a substantially C-shaped magnetic yoke 10 having a flat plate shape is used, and a magneto-optical element 14 is disposed in a gap 12, and the opposite side of the gap 12 is provided. The coil 16 is provided at the center of the yoke. This is so as not to obstruct the light beam passing through the magneto-optical element 14. Alternatively, a magnetic yoke shape 18 having a shape as shown in FIG. 9B is used, and the magneto-optical element 14 is arranged in the gap 12 formed between the tip of the central leg of the magnetic yoke and the outer peripheral portion, and There is also a structure in which the coil 16 is provided on the proximal end side of the leg portion.

[0004]

[Problems to be solved by the device]

 However, in such a conventional configuration, since the coil position is separated from the gap position, even if the magnetic flux generated in the magnetic yoke by the coil is large, the leakage magnetic flux in the magnetic circuit is large, and the magnetic flux near the gap is large. Becomes smaller. Therefore, when it is necessary to apply a large magnetic field to the magneto-optical element, a large magnetomotive force is required, and the number of turns of the coil must be increased or the exciting current must be increased. Larger size and higher power consumption. Further, when the number of coil turns is large, there is a drawback that the inductance increases and the response time required for switching becomes long.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to downsize the device, to drive with a small electric power, and to shorten the response time, and an electromagnetic drive type magneto-optical device. Is to provide.

[0006]

[Means for Solving the Problems]

 The present invention that can achieve the above object is an electromagnetic drive type magneto-optical device in which a gap is provided in a magnetic circuit formed by a magnetic yoke, a magneto-optical element is disposed in the gap, and a coil is provided so as to surround the gap. is there. More preferably, a magnetic circuit having a gap is formed by arranging two magnetic yokes having the same shape so as to face each other, a magneto-optical element is arranged in the gap, and a bobbin surrounds the gap. Provide a coil with windings.

Here, the magnetic yoke has, for example, an E shape in which a central leg is shorter than both side legs, and a light beam passage hole penetrates the central leg. Alternatively, one leg may have a U-shape that is shorter than the other leg, and the light beam passage hole may penetrate through the shorter leg, or the central tube part may be shorter than the peripheral wall part and the end plate may be formed at one end thereof. The structure may be connected by parts. The bobbin has a structure in which two half bobbins integrally formed with a cylindrical portion fitted to the magnetic yoke and a flange portion located at one end of the bobbin are combined by interposing an element holder between them. The structure is such that steps are formed on both sides of the annular part to fit the bobbin cylindrical part. Then, the magneto-optical element is attached to at least one surface of the element holder. Alternatively, the bobbin is provided with a cylindrical portion that fits into the shorter leg of the magnetic yoke or the central cylindrical portion, and flange portions that are integrally molded at both ends of the bobbin, and an inner diameter is formed in the center of the inner peripheral surface of the cylindrical portion. Different steps are provided. In this case, the element holder has a ring shape, and is attached to the step while being in contact with the step on one surface and the magneto-optical element on the other surface.

Further, the magnetic yoke has a flat plate E-shaped structure in which the central leg is shorter than both side legs, and the magnetic yokes are combined so as to face each other so as to have a gap, and they are arranged in two steps with a spacer interposed therebetween. Alternatively, the magneto-optical element may be arranged in the gap, and the coil may be provided so as to surround both gaps.

[0009]

[Action]

 When the winding is provided so as to surround the gap provided in the magnetic yoke, the magnetic field of the solenoid coil is increased and the magneto-optical element arranged in the gap is efficiently magnetized. Further, the magnetic flux density passing through the magnetic yoke also increases, and the magnetic field acting on the gap becomes stronger, so that the magneto-optical element is magnetized more strongly. Therefore, even if the magnetomotive force is small, it can be sufficiently saturated. Therefore, the number of windings of the coil may be small, and the exciting current may be small, and as a result, a device having a small size and a small driving power can be obtained. Further, for the above reason, the number of turns of the coil can be reduced, the magnetic path length of the magnetic circuit can be shortened, and these effects can be combined to reduce the inductance and realize high-speed switching.

[0010]

【Example】

 1 to 3 show an embodiment of an electromagnetically driven magneto-optical device according to the present invention. FIG. 1 is a sectional view thereof, FIG. 2 is a perspective view of an assembly without windings, and FIG. It is an exploded perspective view. Two magnetic yokes 20 having the same shape are combined so as to face each other to form a magnetic circuit having a gap 22, a magneto-optical element 24 is arranged in the gap 22, and a bobbin is wound so as to surround the gap 22. The coil 26 is provided.

The magnetic yoke 20 has an E shape in which a central leg 20 a is shorter than both side legs 20 b, and a light beam passage hole 28 penetrates through the central leg 20 a. In this embodiment, the central leg 20a and the side legs 20b have a substantially circular cross section. The magnetic yoke 20 is made of, for example, ferrite.

Next, the bobbin 30 is a half bobbin 32 in which a cylindrical portion 32a just fitted to the central leg 20a of the magnetic yoke 20 and a flange portion 32b located at one end thereof are integrally formed by resin molding. Two flanges 32b are arranged facing each other so that they are on the outside. Then, the element holder 34 is interposed between the cylindrical portions 32a. The element holder 34 has stepped portions 34a formed on the outer peripheral edges of both surfaces of the annular portion, into which the bobbin cylindrical portion 32a is fitted, and the magneto-optical element 24 is attached to at least one surface of the element holder 34. The magneto-optical element 24 is, for example, a bismuth-substituted rare earth iron garnet single crystal film (LPE film) formed by liquid phase epitaxial growth.

The magneto-optical element 24 and the element holder 34, and the element holder 34 and the half bobbin 32 are fixed by an adhesive. Then, winding is applied around them to form a coil. The bobbin 30 also functions to position the magnetic yoke 20. The center leg 20a of the magnetic yoke 20 is fitted into the hole of the half bobbin 32, and the end faces of both side legs 20b of both magnetic yokes 20 are abutted. At this time, since the central leg 20a is short, a gap 22 is formed between the end faces of both central legs, and the magneto-optical element 24 is located in this gap 22.

By energizing the coil winding, a magnetic flux is generated in the magnetic yoke 20 and a magnetic field is generated in the gap 22. Since the gap portion is surrounded by the coil, the leakage magnetic flux is small, and the generated magnetic flux almost completely passes through the magneto-optical element 24 and magnetizes it. The magnetic field causes an operation such as rotating the polarization plane of the magneto-optical element 24 to a predetermined angle.

FIG. 4 and FIG. 5 show another example of the magnetic yoke that can be used in the present invention. In FIG. 4, the magnetic yoke 40 has a U-shape in which one leg 40a is shorter than the other leg 40b, and the light beam passage hole 42 penetrates the shorter leg 40a. When both magnetic yokes 40 face each other, a gap is formed between the end faces of the shorter leg 40a. Therefore, the magneto-optical element is arranged in this gap. The magnetic yoke 40 is also made of, for example, ferrite. The bobbin, the element holder, the magneto-optical element, etc. incorporated between the two magnetic yokes can have the same structure as that shown in FIG.

Next, the magnetic yoke 50 shown in FIG. 5 has an integral structure in which the central cylindrical portion 50a is shorter than the peripheral wall portion 50b and one end thereof is connected by the end plate portion 50c. The magnetic yoke having such a shape may be made of ferrite or a metal material. When the two magnetic yokes 50 face each other and abut against each other, a gap is formed between the end faces of the short central tubular portion 50a, so that the magneto-optical element is arranged in the gap. Also in this case, the coil structure shown in FIG. 3 can be incorporated as it is. However, in the case of FIG. 5, since the magnetic yoke is cylindrical as a whole, a problem remains in terms of thinning, and it is slightly disadvantageous in mounting in comparison with the case of each of the above embodiments. In this magnetic yoke 50, the hole provided in the central tubular portion 50a becomes the light beam passage hole.

FIG. 6 shows another example of the bobbin that can be used in the present invention, and FIG. 7 shows a cross section of a magneto-optical device using the bobbin. When using the magnetic yoke as shown in FIG. 1, for example, the bobbin 60 includes a cylindrical portion 60a fitted to the central leg of the magnetic yoke 20 and flange portions 60b integrally formed at both ends thereof. Then, a step 60c having a different inner diameter is provided near the center of the inner peripheral surface of the cylindrical portion 60a. On the other hand, the element holder 62 may have a simple annular shape, and is set to have an outer shape that can pass through the large inner diameter portion of the cylindrical portion 60a but cannot pass through the small inner diameter portion. Then, one surface is attached in contact with the step 60c, and the magneto-optical element 64 is attached to the other surface of the element holder 62. When the magneto-optical element is not a thin structure such as the LPE film but a block-shaped element, it is possible to directly attach it to the step 60c without using an element holder.

Even when such a bobbin 60 is used, as shown in FIG. 7, the magneto-optical element 64 can be arranged in the gap 22 formed by the magnetic yoke 20, and a coil can be provided so as to surround it. It goes without saying that a predetermined winding is provided on the outer circumference of the bobbin 60. A gap is formed between the large inner diameter portion of the cylindrical portion 60a and the central leg of the magnetic yoke, but if a cylindrical spacer 66 is fitted in the gap, accurate positioning / holding is possible. This bobbin can also be applied to the magnetic yoke having the structure shown in FIG. 4 or 5. However, since it is necessary to insert and fix the element holder with the magneto-optical element inside the bobbin, the work becomes slightly difficult when the bobbin becomes long. In this respect, the bobbin having the two-part structure has better assembling workability.

FIG. 8 shows still another embodiment of the present invention. The magnetic yoke 70 has a flat plate E-type structure in which the center leg is shorter than both side legs, and the magnetic yokes 70 are assembled so as to face each other and have a gap 72. And stack them. A metal material is preferable for the magnetic yoke 70. The spacer 74 may be a magnetic material or a non-magnetic material, and in the case of a magnetic material, it can be adjusted to a predetermined interval by laminating a plurality of metal materials same as the magnetic yoke. Then, the magneto-optical element 76 is arranged in the gap portion, and the coil 78 is provided so as to surround both gaps. It should be noted that although depending on the position of the spacer 74, if it is located at the light beam passage portion, it is necessary to provide the light beam passage hole 75.

The magneto-optical device shown in FIG. 8 has substantially the same size and shape as the conventional magneto-optical device shown in FIG. 9B. Therefore, the characteristics of both were measured, and the performance was compared and examined. In the case of the structure shown in FIG. 9B, in order to give a magnetic flux density of 163 G to the LPE film, the number of coil turns (wire diameter 0.12 mmφ) was set to 30 and a current of 1.1 A was required to flow. At this time, the inductance of the coil is 37.1 μH and the resistance value of the coil is 0. It was 44Ω, the response time was 123 μS, and the power consumption was 0.53 W. On the other hand, in the structure shown in FIG. 8, when the magnetic flux density of the LPE film is 178 G, the required current value is 1.1 A, the number of coil turns is eight, the coil inductance is 0.302 μH, and the coil resistance value is It was decreased to 0.106Ω, the response time was 3.5 μS, and the power consumption was 0.13 W, which was a remarkable decrease.

Although the embodiments of the present invention have been described above, the present invention is not limited to the structure shown in the drawings, and various modifications can be made. For example, the shape of the magnetic yoke is a circular cross section as a cross section of the leg portion, especially the central leg, but that portion may be a square cross section or an elliptical cross section. Along with that, the shape of the cylindrical portion of the bobbin is changed from a cylindrical shape to a rectangular cylindrical shape or an elliptic cylindrical shape.

[0022]

[Effect of device]

 In the present invention, the magneto-optical element is arranged in the gap formed in the magnetic circuit, and the coil is provided so as to surround the gap. Therefore, the magnetic field generated by the coil is effectively applied to the magneto-optical element, The magneto-optical element is efficiently magnetized, so that it can be sufficiently saturated even if the magnetomotive force is small. As a result, the number of coil turns may be small, and the exciting current may be small, resulting in a compact device with low driving power. In addition, since the number of coil turns can be reduced, the magnetic path length of the magnetic circuit can be shortened, and the effects of these can be combined to reduce the inductance, the response time due to the transient phenomenon of the current can be shortened, and high-speed switching can be achieved. It will be possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a magneto-optical device according to the present invention.

FIG. 2 is an assembled perspective view excluding the winding.

FIG. 3 is an exploded perspective view excluding windings.

FIG. 4 is a perspective view showing another embodiment of the magnetic yoke.

FIG. 5 is a perspective view showing still another embodiment of the magnetic yoke.

FIG. 6 is a partially cutaway perspective view showing another embodiment of the bobbin.

FIG. 7 is a sectional view showing an example of a magneto-optical device using the bobbin.

FIG. 8 is an explanatory view showing still another embodiment of the magneto-optical device according to the present invention.

FIG. 9 is an explanatory diagram showing an example of a conventional technique.

[Explanation of symbols]

 20 magnetic yoke 22 gap 24 magneto-optical element 26 coil 28 light beam passage hole 30 bobbin 32 half bobbin 34 element holder

Claims (8)

[Scope of utility model registration request] 1. An electromagnetic drive type magneto-optical device in which a gap is provided in a magnetic circuit formed by a magnetic yoke, a magneto-optical element is arranged in the gap, and a coil is provided so as to surround the gap. 2. A magnetic circuit having a gap is formed by arranging two magnetic yokes having the same shape so as to face each other, a magneto-optical element is disposed in the gap, and the bobbin is wound so as to surround the gap. An electromagnetically driven magneto-optical device provided with a coil having a wire. 3. The magneto-optical device according to claim 2, wherein the magnetic yoke is E-shaped with a central leg shorter than both side legs, and a light beam passage hole penetrates through the central leg. 4. The magneto-optical device according to claim 2, wherein the magnetic yoke has a U-shape in which one leg is shorter than the other leg, and the light beam passage hole penetrates the shorter leg. 5. The magneto-optical device according to claim 2, wherein the magnetic yoke has a central tubular portion shorter than the peripheral wall portion and is connected at one end thereof by an end plate portion. 6. The bobbin is a combination of two half bobbins integrally formed with a cylindrical portion fitted to a central leg of a magnetic yoke and a flange portion located at one end thereof, with an element holder interposed therebetween. 4. The magneto-optical device according to claim 3, wherein the element holder has a structure in which a step portion into which a bobbin cylindrical portion is fitted is formed on both surfaces of an annular portion, and a magneto-optical element is attached to at least one surface of the element holder. . 7. The bobbin includes a cylindrical portion fitted to the shorter leg of the magnetic yoke or the central cylindrical portion, and flange portions integrally formed at both ends thereof, and an inner diameter is formed substantially at the center of the inner peripheral surface of the cylindrical portion. Different step is provided, and the element holder is attached in a state in which the element holder has an annular shape and is in contact with the step on one surface, and the magneto-optical element is attached to the other surface of the element holder. 5. The magneto-optical device according to item 5. 8. The magnetic yoke has a flat plate E-shaped structure in which a central leg is shorter than both side legs, and the magnetic yokes are combined so as to face each other so as to have a gap. An electromagnetic drive type magneto-optical device in which a magneto-optical element is arranged in the gap portion and a coil is provided so as to surround both gaps.