JP4105892B2 - Core and electrodeless lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrodeless lamp using an electromagnetic inductively coupled discharge (H discharge), particularly to an electrodeless compact fluorescent lamp.
[0002]
[Prior art]
The electrodeless lamp is literally a lamp having no electrode, and has attracted attention in recent years because it has a long characteristic as compared with a fluorescent lamp or the like in which the electrode is a main element that determines the lifetime.
As one form of such an electrodeless lamp, there is a structure having an arc tube having a cylindrical recess and an excitation coil buried in the recess. When an alternating current magnetic field is generated in the arc tube by flowing a high frequency (several MHz to several tens of MHz) alternating current through the coil, the inert gas sealed in the arc tube by the alternating magnetic field. And Hg gas plasma is generated, and the visible light excited from the phosphor applied to the inner wall of the arc tube is generated by the ultraviolet rays generated at this time.
[0003]
Conventionally, a cylindrical core made of soft magnetic ferrite (MnZn ferrite or NiZn ferrite) is inserted into the excitation coil as a magnetic core.
[0004]
[Problems to be solved by the invention]
By the way, in the said conventional electrodeless lamp, since it drive | operates with the high frequency alternating current power of the very high area | region of several MHz-several tens MHz, durability of the electronic component which comprises the high frequency circuit which produces the said electric power falls In addition, there is a problem that the cost is high because it is necessary to take measures against unnecessary radiation from the excitation coil and power supply noise. In Japan, it may be difficult to use due to laws and regulations such as the Electrical Safety Act.
[0005]
Therefore, an electrodeless lamp specification that emits light at several tens to several hundreds of kHz can be considered, but it is not a good idea to use the above-described soft magnetic ferrite core for the excitation coil for the following reason.
That is, if the high frequency is about several hundred kHz, there is a possibility that a soft magnetic metal can be used as the core material. However, the soft magnetic ferrite has a saturation magnetic flux density of 1 compared to the soft magnetic metal material. This is because the temperature is as low as about 2 to 1/4, and the Curie temperature is also lower than that of the soft magnetic metal material. Furthermore, soft magnetic ferrite is disadvantageous in terms of cost (unit price as a core) and weight reduction of the lamp as compared with soft magnetic metal.
[0006]
However, if the core material is simply replaced from soft magnetic ferrite to soft magnetic metal, even if it is several tens to several hundreds of kilohertz, the loss due to eddy currents is large due to the high frequency, and it is very practically used. Hateful.
In view of the above problems, the present invention provides a core made of a soft magnetic metal that can be applied to an excitation coil of an electrodeless lamp by effectively reducing loss caused by eddy currents, and an electrodeless electrode having the core The purpose is to provide a lamp.
[0008]
In order to achieve the above object, a core according to the present invention is a core used with an excitation coil of an electrodeless lamp, has a uniaxial magnetic anisotropy, has a specific resistance value, initial permeability, and generation of the excitation coil. In the soft magnetic metal plate having a thickness thinner than twice the skin depth determined by the frequency of the alternating magnetic field to be applied, the direction of the axis of hard magnetization and the passage direction of the magnetic flux generated by the excitation coil substantially coincide with each other. A soft magnetic metal plate cylindrical body in which a plurality of cylindrical bodies having different diameters that are rolled into a cylindrical shape are stacked substantially concentrically, and an insulating layer disposed between the cylindrical bodies. It is characterized by that.
[0009]
Furthermore, it has a cylindrical body made of soft magnetic ferrite disposed between the cylindrical body of the soft magnetic metal plate and the excitation coil.
The soft magnetic metal plate is a silicon steel plate.
The soft magnetic metal plate is made of a soft magnetic amorphous alloy.
[0010]
In order to achieve the above object, an electrodeless lamp according to the present invention is an electrodeless lamp having a discharge tube filled with a discharge substance and having an arc tube having a recess, and an excitation coil immersed in the recess. The said core is used with the excitation coil, It is characterized by the above-mentioned.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a partially cutaway longitudinal sectional view of an electrodeless fluorescent lamp (hereinafter simply referred to as “electrodeless lamp”) 10 using electromagnetic inductively coupled discharge (H discharge) according to the first embodiment. is there.
[0012]
The electrodeless lamp 10 is made of translucent glass and has an arc tube 12 having an inner wall coated with a phosphor. In the arc tube 12, mercury (Hg) and an inert gas such as krypton (Kr) gas are sealed as discharge substances.
The arc tube 12 has a cylindrical recess 14.
A core 20 in which an excitation coil 18 is wound around the outer periphery is provided so as to be immersed in the recess 14.
[0013]
A cylindrical portion 24 of an aluminum heat sink 22 is inserted on the inner peripheral side of the core 20 as a heat radiation means for preventing the core 20 from overheating. The heat sink 22 has a cup-shaped portion 26 extended to the cylindrical portion 24, and the cup-shaped portion 26 is fixed to a circuit case 28 made of synthetic resin.
In the circuit case 28, a high-frequency driving circuit 30 that is connected to the excitation coil 18 and allows high-frequency alternating current to flow through the excitation coil 18 is housed.
[0014]
In addition, a base 32 having the same standard as that of a general incandescent bulb is attached to the circuit case 28, and power from a commercial power source is supplied to the high-frequency driving circuit 30 through the base 32.
In the electrodeless lamp 10 having the above-described configuration, a high-frequency excitation current is allowed to flow from the high-frequency drive circuit 30 to the excitation coil 18 so that the enclosed gas (Hg + Kr) containing mercury enclosed in the arc tube 12 is mainly illustrated. A plasma discharge is formed in a region indicated by the middle 34, and this plasma (encapsulated gas) is electrically coupled to the excitation coil 18 as a secondary coil, so that the discharge state is stabilized. By the discharge, ultraviolet rays are emitted from the mercury, and the phosphor applied to the inner wall of the arc tube 12 is excited by the ultraviolet rays to generate visible light. In the present embodiment, the frequency of the alternating current supplied to the excitation coil 18 is set in the range of 75 to 450 [kHz].
[0015]
FIG. 2 is a perspective view showing a schematic configuration of the core 20 around which the excitation coil 18 is wound.
In the drawing, the excitation coil 18 is drawn as a single wire for convenience, but is actually a stranded wire called a litz wire. The excitation wire 18 is formed by winding the stranded wire around the outer periphery of the substantially central portion in the longitudinal direction of the cylindrical core 20 in a direction perpendicular to the axial direction of the core 20. The number of windings is 40 [turns], and the core 20 is wound over about 15 (= L1) [mm] in the axial direction.
[0016]
As will be described later, the core 20 is formed by winding a ribbon made of a soft magnetic metal in close contact with a cylindrical shape a plurality of times (in this example, about 10 times). The main dimensions of the core 20 are as follows: The total length L2 is 45 [mm], the outer diameter φ1 is 15 [mm], and the wall thickness T1 is about 0.8 [mm].
FIG. 3 is a view showing a soft magnetic metal plate used as a material of the core 20. In the present embodiment, a silicon steel plate 36, which is a kind of electromagnetic steel plate, is used as the soft magnetic metal plate, and an insulator is coated on one surface thereof to form an insulator layer. It should be noted that an insulator may be coated on both sides as well as on one side. The silicon steel plate 36 having a silicon (Si) content of 3 [wt%] and a thickness of 0.08 [mm] is used. The reason why 3% by weight is used is that this content is generally more common in the market than other content and is easily available. The plate thickness is determined from the viewpoints described below.
[0017]
That is, the thickness of the silicon steel plate 36 is determined in relation to the skin depth. A phenomenon in which a high-frequency magnetic field is localized only near the surface of the conductor due to the generation of eddy current and does not enter the inside is called a skin effect. The skin depth refers to the strength of the magnetic field on the conductor surface being 1 / e (e : Depth that decays to the base of natural logarithm (depth from the surface). When the conductor is a thin plate, the skin depth δ is obtained by the following approximate expression.
[0018]
δ = [(2 × ρ) / (2 × π × f × μ _i ・ Μ ₀ )] ^1/2 … ▲ 1 ▼
ρ: Conductor specific resistance
f: Frequency of magnetic field (frequency of alternating current flowing through excitation coil)
μ _i : Initial permeability of conductor
μ ₀ : Permeability of vacuum (= 4π × 10 ^-7 )
The thickness of the silicon steel sheet needs to be thinner than the skin depth determined by the formula (1), considering the effect of the classic eddy current. In the present embodiment, since the excitation coil is arranged on the outer periphery of the silicon steel plate 36 wound in a cylindrical shape, a magnetic field enters the silicon steel plate 36 from both sides. Therefore, the thickness of the silicon steel plate 36 may be made thinner than twice the skin depth. Here, the specific resistance value ρ of the silicon steel plate 36 is 47 [μΩ · cm], and the initial permeability μ _i Is 400, so if f is 100 [kHz], the skin depth δ is 0.054 [mm] from the formula (1). Considering a value 0.108 [mm] that is twice the skin depth δ, a value that is sufficiently thinner than this is taken to be a plate thickness of 0.08 [mm]. The reason why the insulating coating layer is formed on one or both sides of the silicon steel plate 36 is that when the silicon steel plate 36 is wound in close contact with each other, when there is no insulating layer, the plate thickness is electrically effective. It is the same as the increase, and the purpose of determining the thickness as described above is lost.
[0019]
For example, the silicon steel plate 36 is obtained by cutting a rolled silicon steel strip having uniaxial magnetic anisotropy manufactured by a steel plate manufacturer in an appropriate direction determined in relation to the rolling direction (magnetization easy axis direction). Be prepared.
In a uniaxial magnetic anisotropic silicon steel strip produced by rolling, the rolling direction is the easy magnetization axis direction, and the direction orthogonal to the rolling direction is the hard magnetization axis direction. Such a silicon steel strip is cut into a strip shape to form a silicon steel plate 36 such that the axis of easy magnetization (the rolling direction and the longitudinal direction of the silicon steel strip) is the longitudinal direction.
[0020]
Therefore, as shown by an arrow in FIG. 3, the cut silicon steel plate 36 has the longitudinal direction as the easy axis direction (arrow 38) and the width direction as the hard axis direction (arrow 40). The width L3 (= L2) of the silicon steel plate 36 is 45 [mm], and the total length L4 is 450 [mm].
The silicon steel plate 36 prepared as described above is wound in a roll shape in the longitudinal direction as indicated by an arrow 42 to form a cylindrical shape as shown in FIG. 2 (in this case, approximately 10 turns). . That is, winding is performed so that the direction of the hard axis is substantially coincident with the axial direction of the cylinder. In other words, the winding is performed so that the direction of the hard magnetization axis substantially coincides with the passing direction of the magnetic flux generated by the excitation coil 18 in the silicon steel plate 36. In this case, in view of winding the excitation coil around the cylindrical silicon steel plate 36, it is preferable to wind the coil so that the insulating coating layer is on the outside.
[0021]
Thus, the reason why the direction of the hard axis of the silicon steel plate 36 substantially coincides with the magnetic flux passing direction in the silicon steel plate 36 is to reduce the power loss due to the abnormal eddy current as much as possible, as will be described below. It is.
Here, with respect to power loss, a test was performed to confirm the relationship between the direction of magnetic flux passage and the direction of the hard axis and the presence or absence of magnetic anisotropy.
[0022]
For the test, two types of cores were prepared in addition to the core 20 described above. Hereinafter, one of the two types of cores is referred to as a first comparison core, and the other is referred to as a second comparison core. Both comparative cores are cores having the same shape as the core 20 and are made of a silicon steel plate having the same silicon content, but differ from the core 20 in the following points.
[0023]
The first comparison core is different from the core 20 in the manner of the hard magnetization axis with respect to the magnetic flux passing direction. That is, in the core 20, the magnetic flux passage direction and the direction of the hard magnetization axis are substantially matched, but the first comparison core has the easy magnetization axis direction (perpendicular to the hard magnetization axis) as the magnetic flux passage direction direction. To match.
The second comparative core is made using a silicon steel plate without magnetic anisotropy, that is, a magnetically isotropic silicon steel plate.
[0024]
Each of the core 20, the first comparison core, and the second comparison core was wound in the same manner as shown in FIG. 2 to create an excitation coil. Then, an alternating current of 100 [kHz] was passed through each excitation coil while changing the magnitude of the current, and the magnetic flux density and power loss of the generated magnetic flux were measured.
The measurement results are shown in FIG. FIG. 4 is a graph in which the horizontal axis represents magnetic flux density [T] and the vertical axis represents power loss [W]. The power loss is a total loss including an abnormal eddy current loss described later.
[0025]
FIG. 4 shows that the power loss increases in the order of the first comparison core, the second comparison core, and the core 20 if the magnetic flux densities are the same. This difference is considered to be mainly due to the difference in the magnitude of the abnormal eddy current loss described below.
Magnetization of the magnetic material is performed by the magnetization rotation mechanism in the magnetic domain and the movement of the domain wall separating the magnetic sections. Then, the magnetization caused by the movement of the domain wall has a larger loss than the magnetization caused by the magnetization rotation mechanism (the loss caused by the movement of the domain wall is called “abnormal eddy current loss”).
[0026]
When the passage direction of the magnetic flux is taken as the hard axis direction (core 20), the magnetization rotation mechanism is dominant in the magnetization mechanism of the magnetic material. On the other hand, when the magnetic flux passage direction is the easy magnetization axis direction (first comparison core), the magnetic body magnetization mechanism is dominated by the domain wall movement. As a result, the power loss due to the abnormal eddy current loss is reduced in the core 20 than in the first comparison core.
[0027]
Even when compared with the isotropic second comparative core, the magnetization mechanism of the core 20 is more dominant due to magnetization rotation. As a result, the abnormal eddy current loss of the core 20 is reduced as compared with the second comparative core.
Moreover, it can be seen from FIG. 4 that the difference in power loss between the various cores increases as the magnetic flux density increases. This is because the magnitude of the abnormal eddy current loss depends on the moving distance of the domain wall. That is, if the alternating current has the same frequency (100 [kHz]), the larger the current value (the greater the amplitude of the excitation field), the wider the domain wall movement, resulting in an increase in abnormal eddy current loss. Because it becomes.
[0028]
As described above, although the core 20 according to the first embodiment uses soft magnetic metal, the loss due to eddy current (classical eddy current and abnormal eddy current) is effectively reduced. Therefore, it can be used as a core of an excitation coil in an electrodeless lamp that is lit in a relatively low high frequency region such as 75 to 450 [kHz].
[0029]
In addition, since the Curie temperature of soft magnetic ferrite (MnZn ferrite) conventionally used for electrodeless lamps is about 230 ° C., the Curie temperature of silicon steel sheet is about 700 ° C., which is nearly 500 ° C. Therefore, a more stable electrodeless lamp is obtained.
Furthermore, the saturation magnetic flux density of the silicon steel sheet is 1.7 [T], which is nearly four times that of MnZn ferrite, so that magnetic saturation is unlikely to occur, and the amount of magnetic flux equivalent to that of MnZn ferrite is reduced. If only it can be obtained, the thickness of the cylindrical core can be reduced to about 1/4 that of MnZn ferrite. As a result, it is possible to reduce the weight of the core and thus the overall weight of the electrodeless lamp.
[0030]
In the above embodiment, the insulating coating layer is formed on one surface of the silicon steel plate 36, but instead of the coating layer, a film-like sheet made of an insulating material (hereinafter referred to as “insulating sheet”). 44) may be used.
As the insulating sheet 44, one having a thickness of 80 [μm] is used. The size is the same as that of the silicon steel plate 36, that is, the width is 45 [mm] and the total length is 450 [mm].
[0031]
And as shown in FIG. 5, the said insulation sheet 44 is wound up in the state piled up on the silicon steel plate 36, and it is set as a core.
Further, the silicon steel plate 44 may be wound up in a state sandwiched between two insulating sheets 44.
(Embodiment 2)
The electrodeless lamp according to the second embodiment has basically the same configuration as that of the first embodiment except that the core material is different. Therefore, the description of the common part is omitted, and the explanation will focus on the core.
[0032]
In the first embodiment, the core is manufactured using the silicon steel plate 36. However, in the second embodiment, instead of the silicon steel plate 36, a soft magnetic amorphous alloy plate having uniaxial magnetic anisotropy (hereinafter simply referred to as “amorphous alloy”). 46 "). The amorphous alloy plate 46 is cut out from, for example, an ultra-quenched ribbon (hereinafter referred to as “amorphous alloy ribbon”) of an FeCoSiB-based amorphous alloy. The uniaxial magnetic anisotropy of the amorphous alloy ribbon is obtained by performing an appropriate heat treatment in a uniaxial static magnetic field at a temperature lower than the crystallization temperature in the amorphous material.
[0033]
As in the case of the silicon steel plate 36, the amorphous alloy plate 46 is formed in a strip shape having a width L3 = 45 [mm] and a total length L4 = 400 [mm] so that the axis of easy magnetization is the longitudinal direction. Cut out to obtain (see FIG. 3). The thickness of the amorphous alloy ribbon used (the thickness of the amorphous alloy plate 46) is about 0.05 [mm]. Needless to say, this thickness is smaller than twice the skin depth in the FeCoSiB-based amorphous alloy.
[0034]
In the same manner as described with reference to FIG. 5, a core 50 (see FIG. 2) is formed by winding up an amorphous alloy plate 46 obtained as described above in a state where an insulating sheet 48 of the same size is stacked. Create The number of turns is about 8, the outer diameter φ1 is 15 [mm], and the wall thickness T1 is about 0.05 [mm] (see FIG. 2).
Here, also in the case of an amorphous alloy, the same test as that of the first embodiment is performed to confirm the relationship between the magnetic flux passage direction and the hard axis direction and the presence or absence of magnetic anisotropy regarding power loss. went.
[0035]
That is, from the amorphous alloy ribbon, a third comparative core manufactured by making the easy magnetization axis direction substantially coincide with the magnetic flux passing direction, and a fourth comparative core manufactured by using a magnetically isotropic amorphous alloy ribbon. And the core 50, the third comparative core, and the fourth comparative core were tested under the same conditions as in the first embodiment.
The test results are shown in FIG. From FIG. 6, it can be seen that the core 50 has less power loss than the third comparison core and the fourth comparison core. That is, it has been confirmed that even in an amorphous alloy, the power loss can be reduced by making the passage direction of the magnetic flux inside the magnetic body substantially coincide with the direction of the hard axis.
[0036]
As described above, the core 50 according to the second embodiment also uses soft magnetic metal, but the loss due to eddy current (classical eddy current and abnormal eddy current) is effectively reduced. Therefore, it can be used as a core of an excitation coil in an electrodeless lamp that is lit in a relatively low high frequency region such as 75 to 450 [kHz].
[0037]
Further, the Curie temperature of the amorphous alloy is about 380 ° C., which is about 150 ° C. higher than the Curie temperature of MnZn ferrite, so that an electrodeless lamp that is more stable in terms of temperature characteristics is obtained.
Furthermore, since the saturation magnetic flux density of the amorphous alloy is 1.6 [T], which is 3 to 4 times that of MnZn ferrite, magnetic saturation is unlikely to occur. The thickness of the core can be reduced to about 1/3 to about 1/4 of the case of MnZn ferrite. As a result, as in the case of the first embodiment, it is possible to reduce the weight of the core, and thus the overall weight of the electrodeless lamp.
[0038]
In the above example, the insulating sheet 48 is overlapped and wound around the amorphous alloy plate 46 to produce the core 50. However, the present invention is not limited to this. It is also possible to produce a core by winding an insulator coated.
(Embodiment 3)
The electrodeless lamp according to the third embodiment has basically the same configuration as that of the first and second embodiments except that the core structure is slightly different. Therefore, the description of the common part is omitted, and the explanation will focus on the core.
[0039]
In the third embodiment, a plurality (10 in this example) of cylindrical bodies having different diameters are prepared using the soft magnetic metal plate used in the first and second embodiments as shown in FIG. These cores 52, 54, 56, 58,... (Only 4 out of 10 are drawn in FIG. 7) are stacked substantially concentrically to form a core. did. FIG. 7 shows a state before the cylinders are completely overlapped.
[0040]
The core is manufactured as follows, for example.
First, ten soft magnetic metal plates having the same width and slightly different overall lengths are produced. An insulator is coated on one side of the soft magnetic metal plate. These soft magnetic metal plates are rolled into a single cylinder in the longitudinal direction (full length direction) to form a cylindrical shape. The cylindrical soft magnetic metal plates are inserted into a cylindrical body (not shown) made of synthetic resin in descending order of the diameter. At this time, the orientation of the coating surface is made uniform between the magnetic metal plates. By doing so, a cylindrical core is produced in the cylindrical body made of synthetic resin (hereinafter referred to as “bobbin”).
[0041]
The excitation coil is manufactured by winding a copper wire around the outer periphery of the bobbin. In the above example, the insulator is coated on one surface of the soft magnetic metal plate, but it may be coated on both surfaces.
Furthermore, instead of coating, an insulating sheet may be disposed between the cylinders.
(Embodiment 4)
The electrodeless lamp according to the fourth embodiment is basically the same as the first to third embodiments except that the core structure is different. Therefore, the description of the common part is omitted, and the explanation will focus on the core.
[0042]
In the fourth embodiment, as shown in FIG. 8, a cylindrical body 62 made of soft magnetic ferrite is added to a cylindrical body 60 (core 20, core 50, etc.) made of the soft magnetic metal plate produced in the first to third embodiments. The core 64 is obtained by extrapolating. For example, MnZn ferrite is used as the soft magnetic ferrite.
Some electromagnetic inductively coupled discharge type electrodeless lamps cause a current that is several times to a dozen times as large as that during steady lighting to flow through an excitation coil as a very short time starting current. In the case of such an electrodeless lamp, the cylindrical body 60 made of the above-mentioned soft magnetic metal plate is inserted into a conventional core that is only a soft magnetic ferrite cylindrical body, so that only the soft magnetic ferrite cylindrical body is magnetically saturated. The amount of magnetic flux that is insufficient can be compensated by the cylindrical body 60 made of a soft magnetic metal plate. As a result, the starting characteristics are improved.
[0043]
In the above example, the cylindrical body 60 made of a soft magnetic metal plate is disposed on the inner side, and the soft magnetic ferrite cylindrical body 62 is disposed on the outer side. However, it is preferable to reverse the order of the inner and outer sides. Absent. That is, when a soft magnetic metal plate cylinder exists between the excitation coil and the soft magnetic ferrite cylindrical body, the soft magnetic ferrite cylindrical body has a magnetic shielding effect by the soft magnetic metal plate cylindrical body. This is because the strength of the magnetic field that extends is reduced. Further, by disposing a cylindrical body 60 made of a soft magnetic metal plate on the inner side and a soft magnetic ferrite cylindrical body 62 on the outer side, heat transmitted from the soft magnetic ferrite cylindrical body 60 to the soft magnetic metal plate cylindrical body 60. This is because heat is effectively radiated by the heat sink 22 (see FIG. 1).
[0044]
As described above, the present invention has been described based on the embodiments. However, it goes without saying that the present invention is not limited to the above-described embodiments, and for example, the following forms may be adopted.
(1) In the above embodiment, a silicon steel plate that acquires magnetic anisotropy (uniaxial magnetic anisotropy) by rolling is used. However, the present invention is not limited to this, and uniaxial magnetic anisotropy is obtained by other manufacturing methods. You may use the silicon steel plate which will be exhibited. For example, a technology for making the magnetic domain structure fine and controlling the alignment direction of the magnetic domain by forming a small surface undulation by laser processing the surface of the silicon steel sheet (Ohm's "OHM" February 1972 issue article: Taguchi) , Itakura, and Yamamoto Co.) may be used.
(2) In the above embodiment, the FeCoSiB type soft magnetic amorphous alloy is used. However, the present invention is not limited to this, and for example, a FeSiB type or CoFeB type may be used.
(3) In the above embodiment, the concave portion into which the excitation coil is immersed in the arc tube has a cylindrical shape, but the shape of the concave portion is not limited to this. For example, it may be cylindrical.
(4) In the first, second, and fourth embodiments, the copper wire (stranded wire) is directly wound around the core. However, the present invention is not limited to this, and as introduced in the third embodiment, the bobbin has copper. A wire (twisted wire) may be wound and the core may be inserted into the bobbin.
[0045]
【The invention's effect】
As described above, according to the core according to the present invention, the loss due to eddy current (classical eddy current and abnormal eddy current) is effectively reduced. It can be applied to an excitation coil of an electrodeless lamp. Further, it has a lower Curie temperature and a higher saturation magnetic flux density than a conventional core made of soft magnetic ferrite.
[0046]
Therefore, the electrodeless lamp according to the present invention to which the above-mentioned core is applied is more stable in temperature characteristics and is lighter than the conventional electrodeless lamp using soft magnetic ferrite. As a result, the overall weight can be reduced. The electrodeless lamp according to the present invention can be manufactured at a considerably lower cost than that using a soft magnetic ferrite core.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view in which a part of an electrodeless lamp according to an embodiment is cut away.
FIG. 2 is a perspective view showing a schematic configuration of a core and an excitation coil according to the embodiment.
FIG. 3 is a perspective view showing a soft magnetic metal plate used for the core.
FIG. 4 is a diagram showing magnetic flux density-power loss characteristics in the core according to the embodiment and two comparison cores.
FIG. 5 is a diagram for explaining another example of the core according to the embodiment.
FIG. 6 is a diagram showing magnetic flux density-power loss characteristics in the core according to the embodiment and two comparison cores.
FIG. 7 is a diagram for explaining a core according to a third embodiment.
FIG. 8 is a diagram for explaining a core according to a fourth embodiment;
[Explanation of symbols]
10 Electromagnetic inductively coupled discharge type electrodeless lamp
12 arc tube
14 recess
18 Excitation coil
20, 50, 64 cores
44, 48 Insulation sheet
62 Soft Magnetic Ferrite Cylindrical Body

Claims (5)

A core used with an excitation coil of an electrodeless lamp,
A soft magnetic metal plate having a uniaxial magnetic anisotropy and having a thickness less than twice the skin depth determined by a specific resistance value, initial permeability, and frequency of an alternating magnetic field generated by the excitation coil. Soft magnetism in which a plurality of cylinders having different diameters, which are rounded into a cylindrical shape so that the direction of the hard axis of magnetization and the direction of passage of magnetic flux generated by the excitation coil substantially coincide, are stacked substantially concentrically. A metal plate cylinder;
An insulator layer disposed between the cylinders;
A core characterized by comprising Furthermore, the soft magnetic metal plate cylindrical body and disposed between said excitation coil, a core according to claim 1, wherein a cylindrical body made of a soft magnetic ferrite. The soft magnetic metal plate, according to claim 1 or 2 core, wherein it is a silicon steel sheet. The soft magnetic metal plate, according to claim 1 or 2 core, wherein the made of a soft magnetic amorphous alloy. It is an electrodeless lamp which has the arc tube which has a discharge substance enclosed, and has a crevice, and the excitation coil immersed in the crevice, and it is the electrode coil according to any one of claims 1 to 4 with the excitation coil. An electrodeless lamp, wherein a core is used.

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