JP2006236721A - Field emission type light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a field emission type light source capable of widening an area of a fluorescent face on which electron beam is shed, obtaining a large amount of light, and also capable of eliminating unevenness in light-emitting due to unevenness in electron beam irradiation. <P>SOLUTION: The light source comprises a light transmissive container 2 in which a light transmissive light-extracting part is formed on a part of a tube wall and of which the inside is sealed; an anode layer 4 formed at a side wall except the light-extracting part of the tube wall to work also as a reflective layer; a phosphor layer 6 laminated and formed on the anode layer 4; and a cathode 5 disposed inside the container 2 and having an electron emission source 10b emitting electrons toward the surface of the phosphor layer 6. The emission source 10b is formed of pole-like carbon fiber implanted on the surface of a power supply part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a field emission light source that utilizes light emission of a phosphor by electron beam irradiation, which is used as a work lamp, for example, as a light source for night illumination at an outdoor work site.

  The field emission type light source is known as a lamp having low power consumption and high luminance, and having excellent durability without a weak part such as a filament. A fluorescent display device will be described below as an example of a field emission type light source.

  FIG. 7 is a cross-sectional view showing a configuration of an image tube which is a fluorescent display device disclosed in Japanese Patent Application Laid-Open No. 11-111161.

  A cylindrical glass bulb 101 having an open end at the top is bonded and fixed by a low melting point frit glass 103 so that a stepped portion of the face glass 102 is fitted to the open end to form a sealed structure. A stem glass 108 is formed at the bottom of the glass bulb 101, and an exhaust pipe 108a is formed integrally with the stem glass 108.

  Inside the glass bulb 101, cathode leads 111a and 111b and an anode lead 110 are provided in the tube axis direction and penetrate the stem glass 108 and are connected to lead pins 109a and 109b, respectively. The cathode structure 106 and the anode electrode structure (anode layer) 105 are arranged to face each other in the tube axis direction, supported by the cathode leads 111a and 111b and the anode lead 110, respectively. The anode electrode assembly 105 is disposed closer to the face glass 102 than the cathode assembly 106.

  On the cathode structure 106, needle-like columnar graphite (emitter) 121 made of an aggregate of carbon nanotubes and having a length of several millimeters is fixedly arranged with its longitudinal direction almost directed to the phosphor screen 104.

  The face glass 102 has a convex lens-shaped spherical surface portion 102a formed on the front side thereof. A fluorescent screen 104 is formed on the main surface of the inner surface of the face glass 102, and an Al metal back film 107 is formed on the surface of the fluorescent screen 104.

  The image tube configured as described above first supplies an electric field to the lead pins 109a and 109b from an external circuit, whereby an electric field is generated between the cathode structure 106 as an electrode and the housing 106d via the cathode leads 111a and 111b. generate. Then, a high electric field is concentrated on the tip of the carbon nanotube, which is a columnar graphite fixedly disposed on the electrode (cathode structure) 106, and electrons are emitted. That is, the cathode structure 106 constitutes a field emission type cold cathode electron emission source using carbon nanotubes of columnar graphite as an emitter.

The electrons emitted from the cathode structure 106 are accelerated by the anode electrode structure 105 to which a high voltage is applied, and pass through the Al metal back film 107 and strike the phosphor screen 104. As a result, the phosphor screen 104 is excited by electron impact and emits a light emission color corresponding to the phosphor. The fluorescent light is transmitted through the face glass 102 and emitted to the front side, and a light emission display is performed.
JP-A-11-111161 (paragraph numbers 0002 to 0009)

  However, in the fluorescent display device as described above, the field emission intensity varies greatly depending on the surface state of the cathode and the surface state of the anode layer, and thus it is difficult to make the light emission intensity uniform on the phosphor light emitting surface. Furthermore, when the light emission area is increased in order to increase the light emission amount, there has been a problem that it becomes more difficult to make the light emission intensity uniform.

  The present invention has been made based on such circumstances, and it is possible to increase the area where the electron beam hits the phosphor screen, to obtain a large amount of light, and to eliminate uneven light emission due to uneven electron beam irradiation. An object of the present invention is to provide a field emission type light source capable of performing the above.

  The field emission light source of the present invention includes a translucent container in which a translucent light extraction portion is formed on at least a part of a tube wall and the inside is sealed, and a side wall portion excluding the light extraction portion of the tube wall An anode layer also serving as a reflective layer formed on the inner surface, a phosphor layer formed by being laminated on the anode layer, and an electron emitted from the surface of the phosphor layer disposed in the translucent container A cathode having an electron emission source that is formed of columnar carbon fibers implanted on the surface of the power feeding section.

  Further, in the present invention, the electron emission source is formed by implanting the columnar carbon fiber on the surface of a plurality of rod-shaped power feeding portions radially extending in the anode layer direction in the translucent container, and the fluorescent light source. The body layer is formed by mixing at least two kinds of phosphors.

  Furthermore, in the present invention, the power feeding portion constituting the electron emission source is formed and arranged in a spiral shape so as to be substantially equidistant from the anode layer in the optical container. The field emission light source described.

  Furthermore, in the present invention, the light extraction portion is subjected to a light diffusion treatment by at least one of blasting or scattering particle coating on the inner surface of the tube wall, or blasting on the outer surface of the tube wall. It is characterized by.

  In the field emission type light source of the present invention, by forming the light emitting part and the light extraction part as separate parts of the translucent container, the light emission unevenness due to the unevenness of electron emission, which is a problem of the conventional electron emission type light source, is greatly increased. Thus, a light source that emits light uniformly can be realized.

  The field emission light source of the present invention has a structure in which a phosphor is applied to a conventional light emitting surface, and electrons are directly collided with the phosphor surface without penetrating the anode layer formed as a metal back layer. As a result, the area where electrons hit the surface of the phosphor can be widened. Thereby, a large amount of light can be obtained, and uneven light emission due to uneven irradiation of the electron beam can be eliminated.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a side sectional view of a field emission light source showing a first embodiment of the present invention. The field emission light source 1 includes a translucent container 2 that is hermetically sealed by a translucent tube wall such as glass. The translucent container 2 is formed with a light extraction portion 3-1 having a convex curved surface almost flat at the top, and a substantially hemispherical side wall portion 3-3 around the light extraction portion 3-1. 2 are connected, and a small-diameter electrode extraction portion 3-3 is formed at the bottom of the side wall portion 3-2 of the hemispherical tube wall. The inside of the translucent container 2 is maintained in a vacuum state, and an anode layer 4 and a cathode 5 are stacked on the inner side wall 3-2.

  The anode layer 4 is formed on the entire inner surface of the side wall 3-2 excluding the light extraction part 3-1. A phosphor layer 6 is applied to the surface of the anode layer 4 (the inner surface side of the translucent container 2). For example, silver or aluminum can be used as the anode layer 4, but there is no particular limitation as long as there is a conductive substance. Further, since the anode layer 4 also serves as a reflective layer, a material having a high surface reflectance is preferable. That is, as will be described later, the anode layer 4 is formed so as to reflect the light generated in the phosphor layer 6 in the direction of the light extraction portion 3-1 formed at the top of the field emission light source 1. Therefore, the inner peripheral surface of the side wall 3-2 of the translucent container 2 on which the anode layer 4 is formed also has a substantially hemispherical shape so as to reflect the light generated in the phosphor layer 6 in the direction of the light extraction unit 3-1. It is formed in a surface or parabolic shape.

  A lower end of the anode layer 4 is connected to a conductive piece 8 via a conductive adhesive 7, and an anode layer lead 9 is connected to the piece 8. The anode layer lead 9 is led out of the translucent container 2 while maintaining airtightness from the electrode lead-out portion 3-3.

For example, the phosphor layer 6 is formed by mixing at least two kinds of phosphors of three kinds of red, green, and blue. The red phosphor is, for example, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, the green phosphor is, for example, ZnS: Cu, Al, Zn ₂ SiO ₄ : Mn, and the blue phosphor is, for example, ZnS: Ag, Al, Y ₂ SiO ₅ : Ce, or the like can be used, and any other phosphor that emits light by electron beam irradiation can be used.

  On the other hand, the cathode 5 is disposed substantially at the center of the translucent container 2, connected to the cathode lead 10 by welding or the like and mechanically supported, and extends from the center of the translucent container 2 to the side wall 3-2. It is extended and arranged radially. The cathode 5 is a columnar graphite made of a cylindrical and conductive power supply portion 10a connected to the cathode lead 10 and an infinite number of millimeters of acicular carbon fibers formed on the outer periphery of the power supply portion 10a. 10b. The columnar graphite 10b is formed of columnar graphite (graphite) such as graphite nanofibers and carbon nanotubes, whereby good electron emission characteristics can be obtained at a low voltage.

  The columnar graphite of the cathode 5 is the surface of a plurality of rod-shaped power feeding portions 10 a that extend radially from the substantially central portion of the translucent container 2 toward the side wall portion 3-2, and is formed on the anode layer 4. It is formed over at least approximately a half circumferential surface including the opposing surfaces.

  Carbon nanotubes and carbon nanofibers are “single-walled” tube-shaped substances that are formed by rolling graphite hexagonal mesh planes into a cylindrical shape, or “multi-layered” tube-like materials in which they are nested, and usually have a diameter. Those having a length of 15 nm or less and a length of several tens of nm to several μm are called nanotubes, and those having a diameter of about 15 to 100 nm are called nanofibers. It is produced by arc discharge method, gas phase pyrolysis method, laser sublimation method, electrolysis method, fluidized catalyst method, etc. Recently, hollow tube-like or sometimes empty fiber is also proposed by polymer blend method. . Here, they are called carbon nanotubes or carbon nanofibers in a broad sense including both hollow and empty.

In terms of shape, the cathode 5 is formed radially from the substantially central portion of the translucent container 2 as shown in the schematic plan view of the A ₁ -A ₂ cross section of FIG. 1 shown in FIG. In this case, the distal ends of the plurality of rod-like cathodes 5 extending radially from the central portion and the opposing surfaces of the anode layer 4 are disposed so as to be substantially equal to each other.

  The anode layer lead 9 and the cathode lead 10 are sealed in advance on the stem 11 and led out to the outside while maintaining airtightness from the electrode lead-out portion 3-3. In the electrode take-out part 3-3, after the translucent container 2 is sealed, the inside of the translucent container 2 is evacuated from 10 Pa to 4 Pa or less through the chip 12, and then the chip 12 is heated and melted to chip off (sealing). (Cut off).

  A getter 13 is attached to the cathode lead 10 by welding or the like. The getter 13 is for mainly adsorbing moisture-based impurity gas inside the translucent container 2, and a material such as aluminum zircon is used.

  In the field emission light source 1 configured as described above, a voltage of about 1 to 30 kV is applied between the cathode 5 and the anode layer 4 via the anode layer lead 9 and the cathode lead 10 from an external circuit (not shown). Is done. Thereby, in the cathode 5, a high electric field is concentrated on the tip of the columnar graphite 10 b via the power supply unit 10 a, and electrons are extracted and emitted toward the anode layer 4. The emitted electrons collide with the phosphor layer 6 applied to the inner surface of the anode layer 4. The phosphor layer 6 emits colored light corresponding to the phosphor by electron impact. The emitted light is reflected by the anode layer 4 which also serves as a reflection layer, and is emitted to the outside from the light extraction portion 3 formed in a part of the translucent container 2.

  Although not shown, a three-input field emission light source may be provided by providing a gate electrode for electron emission control near the outside of the cathode 5.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the cathode 5 is constituted by a bowl-shaped power feeding portion 10a ′ in which a columnar graphite 10b is formed on the outer periphery. The opening of the bowl-shaped power feeding part 10a 'is directed toward the light extraction part 3-1, and the columnar graphite 10b is formed on the anode layer 4 side. In FIG. 3, the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the structure of the field emission type light source 1 is substantially the same as that of the second embodiment described above. Therefore, in FIG. 4, the same portion as that shown in FIG. Are denoted by the same reference numerals, and description of each part is omitted to avoid duplication.

  In the third embodiment, the inner side of the light extraction portion 3 of the translucent container 2 is provided with a blasted surface 14 that is blasted as a light diffusion process. Due to the blasted surface 14, the light emitted from the phosphor layer 6 is not emitted as a linear transmitted light from the light extraction unit 3 to the outside, but is diffusely reflected by the irregular reflection surface formed on the blasted surface 14 and scattered light. Are released to the outside. Accordingly, even if the phosphor layer 6 emits light unevenly, the light emitted from the light extraction unit 3 to the outside becomes uniform light emission. The blast surface 14 may be formed not on the inner surface of the light extraction portion 3 but on the outer surface.

  The blasting can be formed by, for example, injecting fine particles such as alumina onto the blasting surface 14 (light extraction portion 3).

  Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, the structure of the field emission light source 1 is almost the same as that of the first embodiment, and therefore, in FIG. 5, the same portion as that shown in FIG. Are denoted by the same reference numerals, and description of each part is omitted.

  In the third embodiment, a scattering particle film 15 is provided as a light diffusion process inside the light extraction portion 3 of the translucent container 2. The scattering particle film 15 is formed using, for example, alumina or titanium oxide. Due to the scattering particle film 15, the light emitted from the phosphor layer 6 is not emitted as linear transmitted light from the light extraction unit 3 to the outside, but is diffusely reflected by the irregular reflection surface formed on the scattering particle film 15 and scattered light. Are released to the outside. Accordingly, even if the phosphor layer 6 emits light unevenly, the light emitted from the light extraction unit 3 to the outside becomes uniform light emission.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. Since the structure of the field emission light source 1 in this fifth embodiment is the same as that in the first embodiment described above, in FIG. 6, the same parts as those shown in FIG. The description of those parts is omitted, and different parts are mainly described.

  In the fifth embodiment, as shown in FIG. 6, a spiral cathode 5 b is provided at a substantially central portion of the translucent container 2. That is, the rod-shaped power feeding portion 10a ″ constituting the cathode 5b is formed in a spiral shape whose diameter gradually increases upward, and columnar graphite 10b is formed in the periphery thereof.

  By using the spiral cathode 5b as the electron emission source, the formation area of the columnar graphite 10b can be increased, and a high current can be taken out. Thereby, the field emission type light source 1 having a high luminous flux can be realized.

  In addition, since the shape of the cathode 5b is spiral, when the light emitted from the phosphor layer 6 is reflected, the light reaches the light extraction unit 3 without much blocking the light traveling straight to the cathode 5b. be able to. As a result, loss during light extraction can be reduced. Therefore, a decrease in the amount of light emitted from the field emission light source 1 can be suppressed.

  In addition, an infinite number of several millimeters of needle-like columnar graphite 10b formed on the outer periphery of the power supply unit 10a when the cathode 5b is formed is usually formed using a CVD apparatus (vapor phase growth apparatus). ing. In a general CVD apparatus, since the flow of the reaction gas is from a certain direction with respect to the workpiece (power supply unit 10a), in a single process, electrons are only applied to the surface exposed to the reaction gas of the workpiece (power supply unit 10a). An emission source 10b is formed. Therefore, it is difficult to form the columnar graphite 10b on the entire circumference of the power feeding portion of the cathode 5b. However, since the shape of the cathode 5b is spiral, a special measure is taken when the electron emission source is formed by making the surface of the cathode 5b on which the columnar graphite 10b is formed face the direction of the anode layer 4. There is no need to apply.

1 is a side sectional view of a field emission type light source showing a first embodiment of the present invention. The top view which shows typically the shape of the cathode shown in FIG. The sectional side view of the field emission type light source which shows the 2nd Embodiment of this invention. The side sectional view of the field emission type light source which shows the 3rd Embodiment of this invention. The sectional side view of the field emission type light source which shows the 4th Embodiment of this invention. The sectional side view of the field emission type light source which shows the 5th Embodiment of this invention. Sectional drawing which shows the structure of the conventional field emission display.

Explanation of symbols

  Bb 1 ... Field emission type light source, 2 ... Translucent container, 3 ... Light extraction part, 4 ... Anode layer, 5, 5a, 5b ... Cathode, 6 ... Phosphor layer, 7 ... Conductive adhesive, 8 ... Section , 9 ... Anode layer lead, 10 ... Cathode lead, 10a, 10a ', 10a "... Power feeding unit, 10b ... Electron emission source, 11 ... Stem, 12 ... Chip, 13 ... Getter, 14 ... Blast processing surface, 15 ... Scattered particle film.

Claims (3)

  A light-transmitting light extraction part is formed on at least a part of the tube wall, and the light-transmitting container whose inside is sealed serves as a reflection layer formed on the inner surface of the side wall part excluding the light extraction part of the tube wall. An anode layer, a phosphor layer formed on the anode layer, and a cathode having an electron emission source disposed in the translucent container and emitting electrons to the surface of the phosphor layer. The field emission type light source is characterized in that the electron emission source is formed of columnar carbon fibers implanted on the surface of the power feeding section.   The electron emission source is planted with the columnar carbon fibers on the surface of a plurality of rod-shaped power feeding portions radially extended in the direction of the anode layer in the translucent container, and the phosphor layer includes at least 2 2. The field emission light source according to claim 1, wherein a plurality of kinds of phosphors are mixed and formed.   2. The field emission light source according to claim 1, wherein the power supply section constituting the electron emission source is formed and arranged in a spiral shape so as to be substantially equidistant from the anode layer in the optical container. .

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