LEE HEE SOO (KR)
SONG JUN KWANG (KR)
LEE HEE SOO (KR)
SONG JUN KWANG (KR)
| WO2005015607A1 | 2005-02-17 |
| US6737809B2 | 2004-05-18 | |||
| JP2000179864A | 2000-06-27 |
| [CLAIMS] [Claim 1]
A plasma lamp, comprising: a waveguide connected to an electromagnetic energy source, the waveguide being made of a dielectric material; a bulb connected to the waveguide, the bulb being charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide; a conductive layer formed on a surface of the waveguide; and a protective layer entirely or partially formed on a surface of the conductive layer. [Claim 2]
The plasma lamp according to claim 1, wherein the protective layer is partially formed on a surface of the conductive layer adjacent to the bulb. [Claim 3]
The plasma lamp according to claim 1, wherein the protective layer is formed on an entire surface of the conductive layer. [Claim 4]
The plasma lamp according to claim 1, wherein the protective layer is made of an inorganic glass composition. [Claim 5]
The plasma lamp according to claim 4, wherein the inorganic glass composition comprises inorganic glass (A), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 30 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 - 5 parts by weight. [Claim 6]
The plasma lamp according to claim 5, wherein the inorganic glass (A) is one or more selected from the group consisting of Siθ2, B2O3, AI2O3, ZnO,
Li 2 O, K 2 O, Na 2 O, BaO, CaO, MgO, SrO, and mixtures thereof. [Claim 7] The plasma lamp according to claim 5, wherein the binder (C) is polyvinyl alcohol or starch. [Claim 8]
The plasma lamp according to claim 1, wherein the protective layer is made of an organic resin composition. [Claim 9]
The plasma lamp according to claim 8, wherein the organic resin composition is present in a liquid phase or vapor phase. [Claim 10]
The plasma lamp according to claim 9, wherein the organic resin composition comprises any one selected from the group consisting of polyparaxylene, polytetraf luoroethylene, and polyimide. [Claim 11]
The plasma lamp according to claim 1, wherein the protective layer is a metal layer. [Claim 12]
The plasma lamp according to claim 11, wherein the metal layer comprises nickel (Ni) or copper (Cu). [Claim 13]
A method of manufacturing a plasma lamp, the plasma lamp including a waveguide connected to an electromagnetic energy source, the waveguide being made of a dielectric material, a bulb connected to the waveguide, the bulb being charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide, and a conductive layer formed on an outer circumference of the waveguide, the method comprising:
I) forming a waveguide;
II) forming a conductive layer on an outer circumference of the waveguide; and
III) forming a protective layer on an outer circumference of the conductive layer. [Claim 14]
The method of manufacturing a plasma lamp according to claim 13, wherein the protective layer is made of an inorganic glass composition. [Claim 15]
The method of manufacturing a plasma lamp according to claim 14, wherein the inorganic glass composition comprises inorganic glass (A), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 30 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 ~ 5 parts by weight. [Claim 16]
The method of manufacturing a plasma lamp according to claim 15, wherein the inorganic glass (A) is one or more selected from the group consisting of SiO 2 , B 2 O 3 , Al 2 O 3 , ZnO, Li 2 O, K 2 O, Na 2 O, BaO, CaO, MgO, SrO, and mixtures thereof. [Claim 17]
The method of manufacturing a plasma lamp according to claim 15, wherein the binder (C) is polyvinyl alcohol or starch. [Claim 18]
The method of manufacturing a plasma lamp according to claim 13, wherein the protective layer is made of an organic resin composition. [Claim 19]
The method of manufacturing a plasma lamp according to claim 18, wherein the organic resin composition is present in a liquid phase or vapor phase . [Claim 20]
The method of manufacturing a plasma lamp according to claim 19, wherein the organic resin composition comprises any one selected from the group consisting of polyparaxylene, polytetraf luoroethylene, and polyimide. [Claim 21]
The method of manufacturing a plasma lamp according to claim 13, wherein the protective layer is a metal layer. [Claim 22] The method of manufacturing a plasma lamp according to claim 21, wherein the metal layer comprises nickel (Ni) or copper (Cu). [Claim 23]
The method of manufacturing a plasma lamp according to claim 13, wherein the (III) forming of the protective layer on the outer circumference of the conductive layer comprises:
III-l) forming a first protective layer on an entire surface of the waveguide formed with the conductive layer; and
111-2) further forming a second protective layer on an entire or partial surface of the waveguide formed with the first protective layer. [Claim 24]
The method of manufacturing a plasma lamp according to claim 23, wherein the first protective layer comprises the same components as the second protective layer. |
[DESCRIPTION] [Invention Title]
PLASMA LAMP COMPRISING PROTECTIVE LAYER AND MANUFACTURING METHOD THEREOF [Technical Field]
The present invention relates to a plasma lamp including a dielectric waveguide and a method of manufacturing the same, and, more particularly, to an improved plasma lamp emitting light by reacting electromagnetic waves transferred through a waveguide made of dielectric materials with rare gases and illuminants charged in a bulb, and a method of manufacturing the same. [Background Art]
As well known to those skilled in the art, a plasma lamp, which is an electrodeless lamp providing a bright white point light source, is characterized in that it has a long effective life span and can provide a bright light source having stable spectra, compared to an electrode lamp. Therefore, the plasma lamp is widely applied in the fields of street lamps, high-resolution monitors, projection TVs, and the like.
A conventional electrodeless plasma lamp is configured such that a bulb charged therein with illuminants and rare gases is placed in a cavity resonator, so that the illuminants and rare gases charged in the bulb react with electromagnetic waves, thereby emitting light. U.S. Patent Nos. 4,954,755, 4,975,625, 4,978,891, 5,021,704, 5,448,135, 5,594,303, 5,841,242, 5,910,710 and 6,031,333 disclose examples of such a conventional electrodeless plasma lamp. However, such a conventional electrodeless plasma lamp is problematic in that since it is limited to a small size, there are many restrictions in applying it to products, such as high-resolution monitors, bright lamps, projection TVs, and the like, in that its structure is complicated, and the production cost thereof is very high, and in that half or more of the energy used to form and maintain plasma disappear in the form of heat emission.
In order to overcome the above problems of the conventional
electrodeless plasma lamp using a cavity resonator, U.S. Patent Application No. 09/809,718 discloses a plasma lamp comprising a dielectric waveguide. This plasma lamp is configured such that plasma is generated using a small amount of energy and heat, generated at the time of the operation of the plasma lamp, is effectively emitted, but is problematic in that its sealing performance is not sufficient. Therefore, Korean Unexamined Patent Application Publication No. 2005-0018587, filed in 2004 by the present inventor, discloses a plasma lamp which can solve this problem, and a method of manufacturing the plasma lamp.
This plasma lamp, disclosed in Korean Unexamined Patent Application Publication No. 2005-0018587, is advantageous in that gases are easily charged in a bulb, and it is possible to prevent the gases charged in the bulb from leaking from the bulb to the atmosphere even at high lamp operation temperatures, thereby solving all the conventional problems.
Meanwhile, there is a conventional plasma lamp in which a conductive layer coated with a metal material, such as silver or the like, is formed on the outer circumference of a waveguide. However, it was found that this conventional plasma lamp is also problematic in that, since the conductive layer is formed on the outer circumference of the waveguide, elements, such as silver (Ag) and the like, present in the conductive layer are easily reacted with components, such as sulfur (S) and the like, present in the atmosphere due to the high heat (approximately 850 " C) generated at the time of the operation of the plasma lamp, so that this plasma lamp corrodes. Further, this conventional plasma lamp is problematic in that, when the conductive layer is coated with the metal material, the edge of the plasma lamp may be not coated therewith, and electric flux lines are concentrated on the uncoated edge of the plasma lamp at the time of the operation of the plasma lamp, so that an arc is generated. [Disclosure] [Technical Problem]
Accordingly, the present invention has been made keeping in mind the
above problems occurring in the prior art, and an object of the present invention is to provide an improved plasma lamp, which can prevent the oxidation and corrosion of metal components present in a conductive layer formed on the outer circumference of a waveguide of the plasma lamp, and a method of manufacturing the same.
Another object of the present invention is to provide a plasma lamp, which can solve the problems occurring in the uncoated edge of the plasma lamp, and a method of manufacturing the same. [Technical Solution]
In order to accomplish the above objects, an aspect of the present invention provides a plasma lamp, including: a waveguide connected to an electromagnetic energy source, the waveguide being made of a dielectric material; a bulb connected to the waveguide, the bulb being charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide; a conductive layer formed on a surface of the waveguide; and a protective layer entirely or partially formed on a surface of the conductive layer.
In the plasma lamp, the protective layer is partially formed on a surface of the conductive layer adjacent to the bulb.
The protective layer is formed on an entire surface of the conductive 1ayer .
The protective layer may be made of an inorganic glass composition.
The inorganic glass composition comprises inorganic glass (A), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 30 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 - 5 parts by weight.
The inorganic glass (A) is one or more selected from the group consisting of SiO 2 , B 2 O 3 , Al 2 O 3 , ZnO, Li 2 O, K 2 O, Na 2 O, BaO, CaO, MgO, SrO, and mixtures thereof.
The binder (C) is polyvinyl alcohol or starch.
The protective layer is made of an organic resin composition.
The organic resin composition is present in a liquid phase or vapor
phase .
The organic resin composition includes any one selected from the group consisting of polyparaxylene, polytetraf luoroethylene, and polyimide.
The protective layer is a metal layer.
The metal layer includes nickel (Ni) or copper (Cu).
Another aspect of the present invention provides a method of manufacturing a plasma lamp, the plasma lamp including a waveguide connected to an electromagnetic energy source, the waveguide being made of a dielectric material, a bulb connected to the waveguide, the bulb being charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide, and a conductive layer formed on an outer circumference of the waveguide, the method comprising: I) forming a waveguide; II) forming a conductive layer on an outer circumference of the waveguide! and III) forming a protective layer on an outer circumference of the conductive layer.
In the method, the protective layer is made of an inorganic glass compos i t ion.
The inorganic glass composition comprises inorganic glass (A), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 30 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 - 5 parts by weight.
The inorganic glass (A) is one or more selected from the group consisting of SiO 2 , B 2 O 3 , Al 2 O 3 , ZnO, Li 2 O, K 2 O, Na 2 O, BaO, CaO, MgO, SrO, and mixtures thereof.
The binder (C) is polyvinyl alcohol or starch.
The protective layer is made of an organic resin composition.
The organic resin composition is present in a liquid phase or vapor phase .
The organic resin composition includes any one selected from the group consisting of polyparaxylene, polytetraf luoroethylene, and polyimide.
The protective layer is a metal layer.
The metal layer includes nickel (Ni) or copper (Cu).
The (III) forming of the protective layer on the outer circumference of the conductive layer includes: 111—1) forming a first protective layer on an entire surface of the waveguide formed with the conductive layer! and 111-2) further forming a second protective layer on an entire or partial surface of the waveguide formed with the first protective layer.
The first protective layer comprises the same components as the second protective layer.
[Advantageous Effects]
As described above, the plasma lamp according to the present invention is advantageous in that, since a protective layer is formed on a conductive layer of a waveguide, it is possible to prevent the conductive layer from being oxidized and corroded, and arc discharge occurring in the region of the uncoated conductive layer can be prevented. [Description of Drawings]
FIG. 1 is a sectional view showing a first example of a plasma lamp according to the present invention;
FIG. 2 is a sectional view showing a second example of a plasma lamp according to the present invention;
FIG. 3 is a sectional view showing a third example of a plasma lamp according to the present invention;
FIG. 4 is a sectional view showing a fourth example of a plasma lamp according to the present invention;
FIG. 5 is a sectional view showing a fifth example of a plasma lamp according to the present invention;
FIG. 6 is a sectional view showing a sixth example of a plasma lamp according to the present invention!
FIG. 7 is a sectional view showing a seventh example of a plasma lamp according to the present invention;
FIG. 8 is a sectional view showing an eighth example of a plasma lamp according to the present invention;
FIG. 9 is a sectional view showing a ninth example of a plasma lamp according to the present invention!
FIGS. 10 and 11 are photographs showing conventional plasma lamps including no protective layers according to Comparative Examples 1 and 2, respectively; and
FIGS. 12 and 13 are photographs showing plasma lamps including protective layers according to Examples 1 and 2 of the present invention, respectively.
[Best Mode]
In order to accomplish the above objects, the present inventors have continuously conducted research on plasma lamps, and, as a result, they found that the above problems of conventional plasma lamps can be solved when a protective layer is additionally formed on a conductive layer of a waveguide. Based on this finding, the present invention was developed.
FIGS. 1 to 9 show various examples of the plasma lamp 100 according to the present invention.
As shown in FIGS. 1 and 2, the plasma lamp 100 includes a waveguide 101 which is made of a dielectric material and is connected to an electromagnetic energy source, and a bulb 102 which is connected to the waveguide 101 and is charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide 101.
The bulb 102 is inserted into a hollow portion 106 of the waveguide 101, and a cavity 102a is formed at an end of the bulb 102, and the cavity 102a is charged with inert gases and illuminants and then sealed by a bulb cover 103. The bulb cover 103 is located at a position having the same height as the top surface of the waveguide 101 such that the bulb cover 103 does not protrude to the outside of the waveguide 101. In addition, the waveguide 101 is provided with other components, such as feed and feedback lines for transferring microwave energy to the waveguide 101 from an electromagnetic energy source (not shown), sensors (not shown) for detecting the change in dielectric constant of a dielectric material, and the like.
A conductive layer 104, which is made of a metal material such as silver (Ag) or the like, is formed on the surface of the waveguide 101, and a protective layer 105, which is made of an inorganic glass composition, an organic resin composition or a metal composition, is formed on the surface of the conductive layer 104. This protective layer 105 serves to prevent the deterioration of the conductive layer 104 and the occurrence of arc discharge at locations near the bulb cover 103.
The protective layer 105 may be formed on the entire surface of the conductive layer 104 as shown in FIG. 1, or may be partially formed only on a part of the surface of the conductive layer 104 adjacent to the bulb cover 103, as shown in FIG. 2. Further, the protective layer 105 may be formed on the top surface of the bulb cover 103 in addition to on the entire surface of the conductive layer 104, as shown in FIG. 3.
As shown in FIGS. 4 to 7, the plasma lamp 200 includes a waveguide 201 which is made of a dielectric material and is connected to an electromagnetic energy source, and a bulb 202 which is connected to the waveguide 201 and is charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide 201. In addition, the waveguide 201 is provided with other components, such as feed and feedback lines (not shown), sensors (not shown), and the like.
The waveguide 201 is provided with a first hollow portion 206 into which the bulb 202 is inserted and a second hollow portion 207 having a larger diameter than that of the first hollow portion 206. The first and second hollow portions 206 and 207 may communicate with each other as shown in FIGS. 4 and 5, and may be separated from each other by a separation layer 208 made of a dielectric material as shown in FIGS. 6 and 7. The bulb 202 is inserted into the first hollow portion 206, and the bulb 202 may be of the same height as the top surface of the waveguide 201 or may protrude to the outside of the waveguide 201. The second hollow portion 207 may be charged with a ceramic dielectric material, such as alumina.
A conductive layer 204 is formed on the surface of the waveguide 201 and the inner circumference of the second hollow portion 207, and a protective layer 205 is formed on the surface of the conductive layer 204 and the inner circumference of the first hollow portion 206.
The protective layer 205 may be partially formed only on the part of the surface of the conductive layer 204 adjacent to the bulb 202, as shown in FIGS. 4 and 6, or may be formed on the entire surface of the conductive layer
204 as shown in FIGS. 5 and 7. Further, the protective layer 205 may be formed such that the bulb 202 is covered therewith.
As shown in FIGS. 8 and 9, the plasma lamp 300 includes a waveguide 301 which is made of a dielectric material and is connected to an electromagnetic energy source, and a bulb 302 which is connected to the waveguide 301 and is charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide 301. In addition, the waveguide 301 is provided with other components, such as feed and feedback lines (not shown), sensors (not shown), and the like.
The waveguide 301 includes a semi spherical bulb receiving groove 306 at one side thereof, and the bulb receiving groove 306 is provided therein with a part of an oval bulb 302. First and second hollow portions 307 and 308 for tuning a resonance frequency are formed in a direction perpendicular to the bulb receiving groove 306, and these first and second hollow portions 307 and 308 may be separated from each other by a separation layer 309 in the waveguide 301 made of a dielectric material.
An outer conductive layer 304 is formed on the surface of the waveguide 301 and the inner circumferences of the first and second hollow portions 307 and 308, and an inner conductive layer 304a may be formed in the waveguide 301. A protective layer 305 is formed on the surface of the outer conductive layer 304. An insulation layer 306a is formed on the bottom surface of the bulb receiving groove 306, and this insulation layer 306a electrically separates the bulb 302 from the inner conductive layer 304a. Further, the insulation layer 306a is connected with the waveguide 301, and thus it is possible to prevent arc discharge from occurring near the bulb 302.
The protective layer 305 may be partially formed only on the surface of the insulation layer 306a and a part of the surface of the outer conductive layer 304 adjacent to the bulb 302, as shown in FIG. 8, or may be formed on the entire surface of the outer conductive layer 304 as shown in FIG. 9. Further, the protective layer 305 may be formed such that the bulb 302 is
covered therewith.
As such, the waveguide of the plasma lamp may have various three- dimensional structures, such as cylinders, hexahedra, prisms, and the like, and may include a plurality of hollows portions in which bulbs, feed lines, feedback lines, sensors, and the like are provided. These hollow portions are located at the places corresponding to maximum electric fields of a resonance frequency of microwaves.
Meanwhile, the plasma lamp may include waveguides having various structures, in addition to the above-described waveguides shown in FIGS. 1 to 9.
The conductive layers 104, 204 and 304, which are formed on the surfaces of the respective waveguides 101, 201 and 301 of the plasma lamp, are chiefly made of silver (Ag). The conventional plasma lamp including the conductive layer made of silver (Ag) is problematic in that, when the plasma lamp is operated, silver (Ag) present in the conductive layer is easily reacted with sulfur present in the atmosphere due to the high heat of about 850 ° C , and thus the conductive layer is converted into a nonconductive layer. Therefore, in the present invention, since the conductive layers 104, 204 and 304 are partially or entirely coated with the protective layers 105, 205 and 305, it is possible to prevent the conductive layers 104, 204 and 304 made of silver (Ag) from directly coming into contact with the atmosphere, so that the oxidization of the conductive layers 104, 204 and 304 can be prevented, and, particularly, it is possible to prevent arc discharge from occurring near bulbs 102, 202 and 302.
Further, the conventional plasma lamp is problematic in that, when a conductive layer is coated on a waveguide, the coating of the conductive layer sometimes may be left out on the edge of the waveguide, and in such case electric flux lines are concentrated on the non-coated edge of the waveguide at the time of the operation of the plasma lamp, so that arc discharge is generated. Therefore, in the present invention, the conductive layer is coated with a specific composition, thus preventing the arc
discharge.
In the present invention, a protective layer formed on the surface of a conductive layer may be made of an inorganic glass composition or an organic resin composition, or may be a metal layer.
In the case where the protective layer is made of the inorganic glass composition, the inorganic glass composition may include inorganic glass (Al), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 5 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 - 20 parts by weight. In the inorganic glass composition, SiO 2 , B 2 O 3 , Al 2 O 3 , ZnO, Li 2 O, K 2 O, Na 2 O, BaO,
CaO, MgO, SrO, and a mixture thereof may be used as the inorganic glass (Al), and water, ethanol, butyl carbitol, or the like may be used as the solvent (B), and polyvinyl alcohol (PVA), ethyl cellulose, or the like may be used as the binder (C).
In the inorganic glass composition, when the amount of the inorganic glass (Al) or the solvent (B) is above or below the mixing ratio, the inorganic glass composition cannot have a viscosity suitable for coating, and it is difficult to form a protective layer having a desired thickness. Further, when the amount of the binder (C) is below the mixing ratio, the dry strength of the formed protective layer is low, and thus the formed protective layer can be easily damaged, and, in contrast, when the amount of the binder (C) is above the mixing ratio, the viscosity of the inorganic glass composition is increased, so that drying time is increased, workability is decreased, and the thickness of the formed protective layer is excessively increased.
Examples of the inorganic glass (Al) may include SiO 2 , serving as a network former used to stabilize glass! B 2 O 3 , serving to increase fluidity! Al 2 O 3 , serving to stabilize glass and increase the chemical durability! ZnO, serving to decrease the softening temperature of glass and prevent devitrification; Li 2 O, K 2 O, and Na 2 O, serving to decrease the softening temperature of glass and increase fluidity! and BaO, CaO, MgO, and SrO,
serving to stabilize glass. These components may be suitably combined depending on the characteristics and use of glass, and the inorganic glass (Al) may include B 2 Os-Si0 2 -based glass, ZnO-B 2 Oa-SiO 2 -based glass, and the like according to the amount and kind of the combined components.
Among these components, it is preferred that single- component compounds, such as AI2O3, SiO 2 , ZrO 2 , TiO 2 , ZnO, and the like; two-component compounds, such as Al 2 O-S 2 O 2 , ZrO 2 -Y 2 Os, and the like; and three-component compounds, such as PbO-SiO 2 -B 2 Os, and the like be used as the inorganic glass
(Al). In particular, it is preferred that the inorganic glass (Al) be selected from the group consisting of SiO 2 , B 2 Os, Al 2 Os, ZnO, Li 2 O, K 2 O, Na 2 O,
BaO, CaO, MgO, and SrO in consideration of the stabilization of glass, the increase in fluidity, the increase in durability of exposure to chemicals, the decrease in softening temperature, and the prevention of devitrification.
In the case where the protective layer is made of the organic resin composition, the organic resin composition may include an organic material (A2), a solvent (B), and a binder (C) such that a mixing ratio of A: B: C is 5 ~ 70 parts by weight: 30 ~ 70 parts by weight: 1 ~ 20 parts by weight. In the organic resin composition, water, ethanol, butyl carbitol, or the like may be used as the solvent (B), and polyvinyl butyral (PVB) may be used as the binder (C). In this case, the mixing ratio is determined depending on working methods, such as silk screen printing methods, dipping methods, and the like, and the organic resin composition is prepared by suitably adjusting viscosity in consideration of temperature, the number of times of application.
As the organic material (A2), epoxy compounds, polyimide, polytetraf luoroethylene (PTFE), or polyparaxylene may be used in a liquid phase or a vapor phase.
In the case where the protective layer is a metal layer, it is preferred that the metal layer include nickel (Ni) in consideration of its ant i-oxidative properties, and include copper (Cu) for considerations of
conductivity even if the metal layer is oxidized to some degree.
The present invention provides a method of manufacturing a plasma lamp, the plasma lamp including a waveguide connected to an electromagnetic energy source, the waveguide being made of a dielectric material, a bulb connected to the waveguide, the bulb being charged with inert gases and illuminants emitting light when electromagnetic energy is transferred to the inert gases and illuminants through the waveguide, and a conductive layer formed on an outer circumference of the waveguide, the method comprising: I) forming the waveguide; II) forming the conductive layer on the outer circumference of the waveguide; and III) forming a protective layer on the outer circumference of the conductive layer.
In the step I), hollow portions 106, 206, 207 and 306 are formed in the waveguides 101, 201 and 301, and the hollow portions 106, 206, 207 and 306 are provided therein with bulbs 102, 202 and 302 and other components.
In the step II), the conductive layers 104, 204 and 304 are formed on the waveguides 101, 201 and 301.
In the step III), the protective layers 105, 205 and 305 are formed partially or entirely on the conductive layers 104, 204 and 304. In this case, these protective layers 105, 205 and 305 may be formed before the bulbs 102, 202 and 302 and other components are provided, or may be entirely formed after the bulbs 102, 202 and 302 and other components are provided.
In the case where a protective layer is formed using an inorganic glass composition, a raw material having a particle size of about 0.1 μm to several tens of μm is formed into a slurry, a subject to be coated is dipped into the slurry and then dried, and then the subject is heat-treated at the temperature at which the inorganic glass composition can be fusion-bonded, thereby forming the protective layer on the subject.
In the case where a protective layer is formed using an organic resin composition, the protective layer can be formed by applying a solid or solution-phase raw material on a subject while the raw material is in a vapor state using a deposition method, and, if necessary, curing the subject. The
protective layer may be formed such that its thickness is about 0.1 - 5 μm on each application of the raw material to the subject. In order to adjust the thickness of the protective layer, if necessary, the raw material may be repeatedly applied on the subject. It is preferred that the waveguide be entirely applied with the composition in the first application and then be entirely or partially applied with the composition in the subsequent repeated applications. [Mode for Invention]
Hereinafter, the present invention will be described in more detail with reference to the following Examples. Here, the present invention is not limited to the following Examples, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
(Comparative Example 1)
A hollow portion was formed in the center of a cylindrical waveguide such that the hollow portion was bored through the cylindrical waveguide, and a bulb was inserted into the hollow portion, and a bulb cover was placed on an end of the bulb, and then the space between the bulb cover and the hollow portion was sealed. A conductive layer was formed on the outer circumference of the waveguide using silver (Ag) paste through a silk screen printing method.
(Comparative Example 2)
A hollow portion was formed in the center of a cylindrical waveguide such that the hollow portion was bored through the cylindrical waveguide, and a bulb was inserted into the hollow portion, and a bulb cover was placed on an end of the bulb, and then the space between the bulb cover and the hollow portion was sealed. A conductive layer was formed on the outer circumference of the waveguide using silver (Ag) paste through a dipping printing method.
(Example 1)
A silver (Ag) conductive layer was formed on the outer circumference of
the waveguide using the same method as in Comparative Example 1.
48 g of SiO 2 , 31 g of PbO, 21g of B 2 O 3 , 50 g of water, and 3g of polyvinyl alcohol were mixed into a slurry, and then the waveguide with the silver (Ag) conductive layer formed thereon was dipped into the slurry, dried at 150°C for 30 minutes, and then heat-treated at 850 ° C for 20 minutes, thereby forming a protective layer including an inorganic glass composition.
(Example 2)
A silver (Ag) conductive layer was formed on the outer circumference of the waveguide using the same method as in Comparative Example 2. The waveguide with the silver (Ag) conductive layer formed thereon was dipped into liquid polytetraf luoroethylene (PTFE), dried at 150+10 ° C for 15 ~ 20 minutes, and then cured at 85±5°C, thereby forming a protective layer including an organic resin composition.
(Experimental Example) Antioxidative effect
Waveguides including none of the protective layers of Comparative Examples 1 and 2, a waveguide including the protective layer including an inorganic glass composition of Example 1, and a waveguide including the protective layer including an organic resin composition of Example 2 were left in the air for a long time. FIGS. 10 and 11 are photographs showing the waveguides including none of the protective layers of Comparative Examples 1 and 2, respectively. FIG. 12 is a photograph showing the waveguide including the protective layer including an inorganic glass composition of Example 1, and FIG. 13 is a photograph showing the waveguide including the protective layer including an organic resin composition of Example 2. From FIGS. 10 and 11, it was found that the waveguides including neither of the protective layers of Comparative Examples 1 and 2 were oxidized, and thus the color of the outer circumferences thereof became black (referring to the arrows in FIGS. 10 and 11). In contrast, from FIGS. 12 and 13, it was found that the waveguides including the protective layers of Examples 1 and 2 were not oxidized, and thus the surfaces thereof were smooth and clear.