JP2015159012A - filament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a filament which has a high efficiency in converting electric power into visible light or near-infrared light.SOLUTION: A filament comprises: a metal base material 2; and a white scatterer layer 1 covering the base material 2. The white scatterer layer 1 is provided with a plurality of open holes 11 formed in the thickness direction. The open hole 11 has a radius which is equal to or shorter than a long wavelength end in the visible light range. Light subjected to heat radiation by the base material 2 is reflected on the white scatterer layer 1 and is then returned to the base material 2. At this time, light having a wavelength equal to or shorter than the radius of the open holes 11, that is, part of the light including the visible light, can be extracted to the outside by making it pass through the open holes 11 on the white scatterer layer 1.

Description

  The present invention relates to a light source filament with improved energy utilization efficiency.

  When a filament made of tungsten or the like is energized and heated, thermal radiation occurs. Incandescent light bulbs using this heat radiation are widely used. However, since most of thermal radiation occurs in the infrared region, conventional filaments do not have high visible light radiation efficiency.

  In Patent Document 1, an infrared light reflecting coat is applied to the surface of a bulb glass, infrared light emitted from the filament is reflected and reabsorbed by the filament, and the filament is reheated to increase efficiency. Proposed.

  Further, in Patent Document 2, by covering the filament with a white scatterer to which a visible light absorber is added, infrared light in the thermally radiated light is reflected by the white scatterer and returned to the filament. A structure for selectively emitting light in the visible light range to the outside is disclosed.

JP 59-58752 A JP2013-134873A

  As in Patent Document 1, the technique in which infrared radiation is reflected by an infrared reflective coating and re-absorbed by a filament does not cause re-absorption efficiently because the reflectance of infrared light by the filament is as high as 70%.

  On the other hand, as in Patent Document 2, the technique of adding a visible light absorber to a white scatterer can suppress the infrared radiation of the white scatterer, but appropriately selects and adds the visible light absorber. There is a need.

  An object of the present invention is to provide a filament having high efficiency for converting electric power into visible light or near infrared light using a white scatterer to which no visible light absorber is added.

  In order to achieve the above object, the filament of the present invention has a metal base material and a white scatterer layer covering the base material. In the white scatterer layer, a plurality of through holes are formed in the thickness direction. The radius of the through hole is not more than the long wavelength end of the visible light region.

  ADVANTAGE OF THE INVENTION According to this invention, the filament with high efficiency which converts electric power into visible light or near-infrared light can be provided using the white scatterer to which no visible light absorber is added.

The perspective view which shows the structure of the filament of embodiment. Sectional drawing of the filament which provided the gap | interval 3 between the white scatterer layer 1 and the base material 2 of embodiment. Sectional drawing of the filament of embodiment. Sectional drawing of the filament of embodiment. The graph which shows the relationship between the input electric power of the filament of an Example, and temperature. The graph which shows the reflection spectrum and emission spectrum of the filament of an Example. The graph which shows the reflection spectrum and emission spectrum of the filament (tungsten base material) of a comparative example.

  A filament according to an embodiment of the present invention will be described.

  As shown in FIG. 1, the filament of the present invention has a metal base 2 and a white scatterer layer 1 covering the base 2. A plurality of through holes 11 are formed in the white scatterer layer 1 in the thickness direction. The radius of the through hole 11 is equal to or less than the long wavelength end of the visible light region.

  The white scatterer layer 1 is composed of white scatterer particles that scatter light. By covering the base material 2 with the white scatterer layer 1, the light thermally radiated from the base material 2 is reflected by the white scatterer layer 1 and returned to the base material 2. At this time, by providing the white scatterer layer 1 with a through hole 11 having a radius not longer than the long wavelength end of the visible light region (for example, about 0.8 μm or less), light having a wavelength equal to or less than the radius of the through hole 11, That is, partial light including visible light can be taken out through the through-hole 11 of the white scatterer layer 1.

ここで、Ｔは透過率、ｒは貫通孔の半径、λは透過する光の波長である。 When light passes through the through-hole 11 having a size (diameter) of about the wavelength, the transmittance is expressed by the following equation (1).

Here, T is the transmittance, r is the radius of the through hole, and λ is the wavelength of the transmitted light.

  From equation (1), it can be seen that the transmittance changes dramatically depending on whether the wavelength of light is larger or smaller than the radius of the through hole 11. That is, light having a wavelength longer than the radius can pass through the through hole 11 only slightly, but light having a wavelength shorter than the radius can pass through the through hole with a large transmittance. Therefore, by setting the radius of the through-hole 11 to be equal to or less than the long wavelength end of the visible light region (for example, about 0.8 μm or less), only the light having a wavelength equal to or less than the radius of the through-hole 11 can be used. Can be transmitted and radiated to the outside.

  Therefore, the radius of the through hole 11 is set according to the wavelength of light desired to be emitted from the white scatterer layer 1. For example, when the filament is used as a visible light source and only the visible light wavelength is desired to be emitted from the white scatterer layer 1, the radius of the through hole 11 is equal to or less than the long wavelength end of the visible light region (for example, about 0.8 μm). Below), and preferably below the infrared wavelength. Specifically, the radius of the through hole 11 is desirably 1.0 μm or less, and particularly desirably 0.8 μm or less. When the filament is used as a light source for a near infrared heater or the like and not only the visible light wavelength but also the near infrared light wavelength is emitted from the white scatterer layer 1, the radius of the through hole 11 is 5.0 μm or less. It is desirable that the thickness be 4.0 μm or less.

  The light emitted from the substrate 2 and entering the through-hole 11 is emitted from one of the openings at both ends of the through-hole 11 while being diffusely reflected by the inner wall of the through-hole 11. At this time, the light emitted from the opening of the through hole 11 on the outer peripheral surface side of the white scatterer layer 1 is emitted toward the outside. On the other hand, the light emitted from the opening of the through hole 11 on the inner peripheral surface side (base material 2 side) of the white scatterer layer 1 reenters the base material 2 and is reabsorbed by the base material 2. For this reason, there is no substantial energy loss even if a part of the light scattered on the inner wall of the through hole 11 is radiated to the substrate 2 side. Therefore, from the viewpoint of the transmittance of the through hole 11, the length of the through hole 11, that is, the thickness of the white scatterer layer 1 may be any thickness.

  On the other hand, the thickness of the white scatterer layer 1 can be set to 10 μm or more from the viewpoint of preventing the emitted light of the base material 2 from passing through the region other than the through-holes 11 of the white scatterer layer 1. desirable. This is because, when the film thickness is less than 10 μm, part of the light may pass through the white scatterer layer 1 due to the mean free path of the scattered light in the white scatterer layer 1.

  Moreover, since the volume of the white scatterer layer 1 will become large and the heat loss in the white scatterer layer 1 will become large if the film thickness of the white scatterer layer 1 is too thick, the film thickness of the white scatterer layer 1 is It is desirable that it is 200 micrometers or less.

  From the above, the thickness of the white scatterer layer 1 is preferably in the range of 10 to 200 μm. Within this range, high reflectance can be maintained while minimizing heat loss.

  It is desirable that innumerable through holes 11 are provided in the white scatterer layer 1. The arrangement may be random or arranged as shown in FIG.

  Further, it is desirable that a gap is provided at least partially between the white scatterer layer 1 and the substrate 2 as shown in FIG. The reason is that when the filament is heated to a high temperature exceeding 2000 ° C., atoms may diffuse between the white scatterer layer 1 and the substrate 2. When the atoms of the base material 2 diffuse into the white scatterer layer 1, it can become the center of absorption in the visible to infrared region, and thus the infrared light reflection function of the white scatterer layer 1 may be reduced. Therefore, it is desirable to provide a gap 3 between the white scatterer layer 1 and the substrate 2 so as not to be in close contact.

  Specifically, for example, as shown in FIG. 3, the white scatterer layer 1 may be a hollow cylindrical member and may be arranged so as to surround the substrate 2. The inner diameter of the white scatterer layer 1 of the cylindrical member is larger than the outer diameter of the substrate 2 or the wound substrate 2, and the white scatterer layer 1 is in close contact with the substrate 2 at least in the center. Not. In the case of FIG. 3, both ends of the white scatterer layer 1 of the cylindrical member are in contact with the base material 2 to support the cylindrical member with respect to the base material 2. Thereby, it can arrange | position with the gap | interval 3 with respect to the base material 1 except the both ends of the white scatterer layer 1. FIG. In addition, as shown in FIG. 3, by closing both ends of the white scatterer layer 1 of the cylindrical member, the light emitted from the base material 2 is separated at the gap 3 at the end of the white scatterer layer 1 of the cylindrical member. There is no leakage from the outside. Therefore, the energy input to the base material is not deprived by radiation other than that radiated from the through hole 11, and the base material 2 can be heated to a high temperature with a small input energy.

  Of the area of the white scatterer layer 1, the area of the region in contact with the substrate 2 is preferably 20% or less.

  Further, as shown in FIG. 4, the white scatterer layer 1 can also be configured such that the diameter of the white scatterer particles increases toward the side closer to the substrate 2. In this case, a part of the white scatterer particles 1 a having a large diameter comes into contact with the substrate 2 to support the white scatterer layer 1 against the surface of the substrate 2. Therefore, the contact area can be 20% or less of the entire area of the white scatterer layer 1.

  The cylindrical white scatterer layer 1 as shown in FIGS. 1 and 3 can be manufactured by molding a slurry in which the white scatterer is dispersed in a solvent by extrusion or the like and then drying it. The white scatterer layer 1 can be fixed to the base material 2 by inserting the base material 2 into the formed cylindrical white scatterer layer 1, applying white scatterer particles to both ends and sintering. At the same time, the gap at both ends of the tube can be closed. Thereby, the filament of the structure of FIG. 3 can be manufactured.

  Further, as shown in FIG. 4, the white scatterer layer 1 in which white scatterer particles having different sizes are deposited is obtained by depositing the white scatterer particles dispersed in a solvent around the substrate 2 by electrophoresis. Can be manufactured.

  As a method of providing the fine through-holes 11 in the white scatterer layer 1, a laser processing method can be used. For example, after the cylindrical white scatterer layer 1 is produced by an extrusion molding method or the like, the fine through-holes 11 can be opened innumerably and randomly using a laser. The larger the number of through holes 11, the better. As the laser beam, one having a wavelength smaller than the diameter of the through-hole 11 provided is preferable. For example, an excimer laser can be used. Further, the through hole 11 can be provided by a method such as reactive ion etching or plasma etching.

  The white scatterer layer 1 preferably has an average particle diameter of white scatterer particles of 1 μm or more and 50 μm or less. The white scatterer layer 1 can also be made from white scatterer particles having different particle sizes. As the particle diameter is larger, the light scattering cross-sectional area is larger. For example, a large particle having a particle diameter of several microns is arranged on the inner wall close to the substrate 2, and a small particle having a particle diameter of several hundred nanometers is disposed on the outer wall. A gradient of the particle diameter is applied so that is arranged.

  In addition, the shape of the base material 2 may be arbitrary, may be linear, the center part may be bent periodically like FIG. 3, and may be wound.

  The metal material constituting the substrate 2 is a metal material having a melting point of 2000K or more, for example, HfC (melting point 4160K), TaC (melting point 4150K), ZrC (melting point 3810K), C (melting point 3800K), W (melting point 3680K), Re (Melting point 3453K), Os (melting point 3327K), Ta (melting point 3269K), Mo (melting point 2890K), Nb (melting point 2741K), Ir (melting point 2683K), Ru (melting point 2583K), Rh (melting point 2239K), V (melting point) 2160K), Cr (melting point 2130K), Zr (melting point 2125K), or an alloy containing any of these can be used.

Examples of the material of the white scatterer layer 1 include HfC, TaC, ZrC, C, W, Re, Os, Ta, Mo, Nb, Ir, Ru, Rh, V, Cr, Zr, SiO ₂ , MgO, and ZrO _2. , Y ₂ O ₃ , 6H—SiC, GaN, 3C—SiC (cubic SiC), HfO ₂ , Lu ₂ O ₃ , Yb ₂ O ₃ , graphite, diamond, CrZrB ₂ , MoB, Mo ₂ BC, MoTiB ₄ , Mo ₂ TiB ₂ , Mo ₂ ZrB ₂ , MoZr ₂ B ₄ , NbB, Nb ₃ B ₄ , NbTiB ₄ , NdB ₆ , SiB ₃ , Ta ₃ B ₄ , TiWB ₂ , W ₂ B, WB, WB ₂ , YB ₄ and ZrB ₁₂ , or a material containing these materials.

  The present invention can provide a filament with high radiation efficiency of visible light and near infrared light by adjusting the diameter of the through hole. A filament having high radiation efficiency in the visible region can be used as a light source for illumination with high efficiency. A filament having high radiation efficiency in the near infrared region can be used as a heat source such as a heater light source. Therefore, the filament of the present invention can be used as, for example, a general illumination light source, an automobile light bulb, a projector light source, a liquid crystal backlight light source, and a near infrared heater.

  Hereinafter, an embodiment of the present invention will be described.

A tube-shaped white scatterer layer 1 having an infinite number of through-holes 11 was prepared using hafnium oxide (HfO ₂ ) as a white scatterer.

  First, a hollow tube of the white scatterer layer 1 having a thickness of about 50 μm was prepared by extrusion molding using white scatterer particles having a particle diameter of 1.0 μm. The inner diameter (hollow diameter) of the white scatterer tube was 500 μm.

  Next, innumerable and random through holes 11 having a radius of about 0.8 μm or less were provided by laser processing.

  A tungsten substrate 2 (φ = 100 μm) was passed through the hollow portion of the white scatterer layer 1. In order to fix both ends of the tube-shaped white scatterer layer 1 to the tungsten substrate 2, hafnium oxide powder was dispersed in ethanol at a high concentration, and a slurry was applied to both ends of the tube. Thereafter, firing was performed at 1500 ° C., and both ends of the tube and the tungsten substrate 2 were joined.

  Thereby, as shown in FIG. 3, in the central part of the tube-shaped white scatterer layer 1, there is a gap between the base material 2 and the white scatterer layer 1, and both ends are joined to the base material 2 Manufactured.

  When the filament is energized and heated, the portion of the tungsten substrate 2 that is hot is near the center, and both ends of the substrate 2 are lower in temperature than the center. For this reason, the tubular white scatterer layer 1 whose both ends are in contact with the base material 2 is held on the tungsten base material 2 without being deteriorated.

  Finally, both ends of the tungsten substrate 2 were connected to lead wires to produce incandescent bulb filaments.

  FIG. 5 shows the relationship between temperature and input power when power is supplied to the filament of the example. As a comparative example, the relationship between the temperature and the input power is also shown for the tungsten base material 2 not provided with the white scatterer layer 1.

  From FIG. 5, it can be seen that the filament of the example reaches the high temperature with a small input power due to the presence of the white scatterer layer 1. That is, it can be seen that the filaments of the examples have less energy loss than the comparative examples, and the efficiency of the filaments is high.

  FIGS. 6 and 7 show the results obtained by simulation of the reflection spectrum and the emission spectrum of the filament of this example and the tungsten substrate 2 of the comparative example in which the white scatterer layer 1 is not provided. Compared with the filament of the example and the comparative example, the reflectance in the visible light region is low, and the reflectance in the infrared light region is high. It can also be seen that infrared radiation is suppressed and visible radiation is high. The visible light radiation efficiency is 12.4 lm / W in the comparative example at 2500 K, whereas the filament of this example is 22.5 lm / W, and an efficiency improvement effect of 81% is obtained. I understood.

  Thus, by covering the filament base material 2 with the white scatterer layer 1 having the through-holes 11, an efficient incandescent bulb filament is obtained in which the radiation in the infrared region is small and the radiation in the visible region is large. It is done.

DESCRIPTION OF SYMBOLS 1 ... White scatterer layer, 2 ... Base material, 3 ... Gap | interval, 11 ... Through-hole

Claims (8)

A metal substrate and a white scatterer layer covering the substrate;
The white scatterer layer has a plurality of through holes formed in a thickness direction, and the radius of the through holes is equal to or less than a long wavelength end of a visible light region.   The filament according to claim 1, wherein a radius of the through hole is smaller than an infrared light wavelength.   The filament according to claim 1 or 2, wherein a gap is provided at least partially between the white scatterer layer and the substrate.   4. The filament according to claim 3, wherein the white scatterer layer is a cylindrical member having a diameter of at least a central portion larger than a diameter of the base material, and both ends of the white scatterer layer are in contact with the base material. A filament characterized by supporting the substrate.   The filament according to any one of claims 1 to 4, wherein a radius of the through hole is 0.8 µm or less.   The filament according to any one of claims 1 to 5, wherein the white scatterer layer has a thickness of 10 µm to 200 µm.   The filament according to any one of claims 1 to 6, wherein an area of a region in contact with the base material is 20% or less in an area of the white scatterer layer. .   The filament according to any one of claims 1 to 7, wherein the white scatterer layer is composed of white scatterer particles, and the diameter of the white scatterer particles is set on the base material of the white scatterer layer. A filament that is larger toward the side and supports the white scatterer layer with respect to the surface of the substrate by a part of the white scatterer particles coming into contact with the substrate.

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