JP2006244855A - Field electron emission type lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a field electron emission type lamp capable of enhancing brightness by heightening electron density of light emission face and obtaining a uniform light emission face. <P>SOLUTION: The field electron emission type lamp is composed of an evacuated light-emitting container, on inner face of which a metal-back film (an anode) having an electron-beam excited phosphor layer is formed; an electron emission source (a cathode) and an electron draw-out electrode (a grid electrode) formed on a metal base plate; and an electromagnetic lens (an electromagnetic filter) converging the drawn-out electron beam. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a field emission lamp capable of changing a focal length.

  Conventionally, incandescent lamps and fluorescent lamps are mainly used as electric lamps and lighting. An incandescent lamp is a light source that generates Joule heat by energizing a tungsten filament disposed therein to raise the temperature of the filament and uses a visible light portion in temperature radiation from the hot filament. Since this incandescent lamp is a point light source, the shadow of an object can be increased, and the three-dimensional effect and texture of the object can be easily obtained. In contrast, fluorescent lamps are generated by applying a phosphor to the inner wall of an elongated glass tube and applying a high voltage between the electrodes at both ends of the glass tube, thereby generating an internal discharge and generating an inert gas. Ultraviolet light excites the phosphor to emit light. Fluorescent lamps are advantageous in that they can express colors close to natural light or have a long lifetime, and are widely used as indoor and outdoor lighting.

  However, with incandescent lamps, high temperature filaments are fragile, have short lifespan, require initial heat at the beginning of operation, have a slow response speed, and require a separate heating power supply, and the structure is complicated. There is. In contrast, fluorescent lamps have advantages such as long life, simple structure and easy miniaturization, but due to aging, there is a difference in brightness between the end electrode and the tube center. There are problems such as adverse effects on the environment due to the use of mercury. In addition, conventional fluorescent display devices consume less power and are less likely to deteriorate over time, but can emit light only in one direction with flat light emission, and the amount of light emission is small compared to incandescent and fluorescent lamps. There is a problem that it is difficult to substitute.

  Therefore, a fluorescent lamp that can be used as illumination with a simple structure, high brightness, high response speed, and long life has been devised by utilizing the principle of a fluorescent display device using a field emission electron source. For example, Patent Document 1 below discloses that a fluorescent display device having a structure in which electrons emitted from an electron emitting portion are controlled by a grid electrode and collided with a phosphor to emit light is used as a light source.

  In particular, as a lamp with low power consumption and high luminance, Patent Document 2 below discloses a field emission type image tube using carbon nanotubes as a cathode electrode as shown in FIG. In FIG. 2, first, an electric field is applied between the electrode 106 and the housing 106d via the cathode leads 111a and 111b by supplying a voltage to the lead pins 109a and 109b from an external circuit. As a result, a high electric field is concentrated on the tip of the carbon nanotube of the columnar graphite 121 fixedly arranged on the electrode 106, and electrons are drawn out and emitted from the mesh portion 106e. Then, a high voltage is supplied from the external circuit to the lead pin 109, and the high voltage is applied to the Al metal back film 107 through the paths of the anode lead 110 → the anode electrode assembly 105 (cylindrical anode 105b) → the contact piece 107a. In this state, the emitted electrons are accelerated by the cylindrical anode 105b and penetrate the Al metal back film 107 to be bombarded on the phosphor screen 104. As a result, the phosphor constituting the phosphor screen 104 is excited by electron impact, and the emission color corresponding to the phosphor is transmitted through the face glass 102 and is emitted and displayed on the front side (face glass 102 side). become.

  Thus, by using carbon, particularly carbon nanotubes, as the cathode electrode, it is possible to obtain a field emission lamp that is stable and reliable over a long period of time.

On the other hand, a box-type field emission lamp is also known. As shown in FIG. 3, electrons emitted from an electron emission source (cathode) 4 composed of an electron source 3 made of carbon nanotubes or the like on a metal substrate 2 are accelerated by an electron extraction electrode 5 in a glass container 1. And a metal back film (anode) 6 having an electron beam excited phosphor layer 7.
JP 2001-176433 A JP 2004-152591 A

  Conventional lamps such as the box-type field electron emission lamps have a problem in that variations in luminance are observed on the light-emitting surface of the light source tube because electrons are not emitted uniformly from the electron source (emitter). This is because the difference in structure factor determined by the shape of the emitter, such as the outer shape and length of the electron source and the distance between the tip of the electron source and the extraction electrode, causes variations in field electron emission characteristics. For example, in an extreme case, the rate at which electrons accelerated by the extraction electrode are bent and collide with the outer wall of the light source tube is high.

  In view of the problems of the prior art, it is an object of the present invention to provide a field electron emission lamp capable of increasing brightness by increasing the electron density of a light emitting surface and obtaining a uniform light emitting surface.

  The present inventor has found that the above problem can be solved by changing the focal length of the electron flow, and has reached the present invention.

  That is, the present invention is an invention of a field electron emission lamp, a light emitting container in which a metal back film (anode) having an electron beam excited phosphor layer is formed on the inner surface and the inside is evacuated, and the interior of the light emitting container A field electron emission lamp comprising an electron emission source (cathode) and an electron extraction electrode (grid electrode) formed on the cathode, and having an electromagnetic lens (electromagnetic filter) for converging the extracted electron beam. Features.

  In the present invention, the electromagnetic lens may be disposed in front of the metal back film (anode), and specifically, between the metal back film (anode) and the electron extraction electrode (grid electrode). It is preferable that they are arranged.

  The shape of the electron emission source (cathode) of the present invention is not limited, but particularly in the case of a planar shape, the electron dose is large, and it is possible to achieve higher brightness by focusing with an electromagnetic lens, and to achieve a uniform effect. Becomes larger.

  In the field electron emission lamp of the present invention, the material of the electron source is not particularly limited. For example, the electron emission source (cathode) is preferably a conductive material or a semiconductor material. More specifically, carbon nanotubes, carbon nanofibers, and sharp diamonds that have a small radius of curvature at the tip and cause a field electron emission phenomenon at a low applied voltage are preferably exemplified. By using carbon nanotubes or carbon nanofibers as the electron emission source, the amount of electrons emitted is increased. For this reason, the fluorescent lamp can achieve a sufficiently high brightness for illumination. In addition, by using a field electron emission source, it is possible to improve the response speed without the need for residual heat that becomes a problem when using an incandescent lamp or the like.

  The shape of the field electron emission lamp of the present invention is not particularly limited, and can take various shapes. Among them, the metal back film (anode) having the electron beam excited phosphor layer is planar, and the light emitting container is box-shaped, and the metal back film (anode) having the electron beam excited phosphor layer is Typically, it is a curved surface and the luminous container is spherical or hemispherical. In addition, by arranging the electron emission source on the surface of the flat cathode disposed under the light emitting container, electrons are drawn from the entire field electron emission source, and the electrons collide with almost the entire region of the light emitting portion on the inner surface of the light emitting container. Since it emits light, a fluorescent lamp without uneven brightness can be obtained. Similarly, by arranging the electron emission source on the spherical or hemispherical cathode surface arranged in the substantially central portion of the light emitting container, electrons are drawn from the entire field electron emission source and substantially the entire region of the light emitting part on the inner surface of the light emitting container. Since the electrons collide with each other and emit light, a fluorescent lamp without uneven brightness can be obtained.

  By using a field electron emission lamp provided with an electromagnetic lens capable of focusing an electron beam, the traveling direction can be made constant. As a result, it is possible to increase the electron density on the light emitting surface to increase the brightness and obtain a uniform light emitting surface. Further, by converging the electron beam, it is possible to concentrate the electron beam at one point to increase the luminance.

  An embodiment of the field electron emission lamp of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of a field electron emission lamp. In the field electron emission lamp, a metal back film (anode) 6 having an electron beam excitation phosphor layer 7 is formed on the inner surface in a glass container 1 having a specific shape, in FIG. An electron emission source (cathode) 4 composed of an electron source 3 and an electron extraction electrode (grid electrode) 5 formed on the cathode 2 of the metal substrate are provided. The inside of the glass container 1 is evacuated. Further, an electromagnetic lens (electromagnetic filter) 8 is disposed between the metal back film (anode) 6 and the electron extraction electrode (grid electrode) 5. Outside the glass container 1, a predetermined field electron emission voltage is provided between the cathode 2 and the metal back film (anode) 6, and a predetermined electron acceleration voltage is provided between the cathode 2 and the electron extraction electrode (grid electrode) 5. Arrange the power supply to apply.

  The electron beam emitted from the electron emission source (cathode) 4 is accelerated by the electron extraction electrode (grid electrode) 5 and converged by the electromagnetic lens (electromagnetic filter) 8, and one point or a predetermined point on the metal back film (anode) 6. Irradiated with an area of. The electron beam-excited phosphor layer 7 emits light with high brightness and uniformity by this electron beam.

  Although a box-type field electron emission lamp has been described as an example in FIG. 1, the field electron emission lamp of the present invention may be spherical.

The electron beam-excited phosphor layer 7 can be used in combination with a white phosphor, a red phosphor, a green phosphor, or a blue phosphor depending on the application, and a paste obtained by dissolving these phosphors in a solvent is made of glass. After coating on the inner surface of the container by a method such as printing / slurry method, it is formed by drying. When the phosphor used specifically is white light such as an electric lamp or an illumination, the white phosphor is ZnS: Ag + ZnS: Cu, Al + Y ₂ O ₂ S: Eu ³⁺ , Y ₂ O ₂ S: Tb + Y ₂ O _{When 3} : Eu or the like is used as colored illumination, a combination of red phosphor Y ₂ O ₃ : Eu, green phosphor ZnS: Cu, blue phosphor ZnS: Ag, or the like can be suitably used.

  The electron source 3 constituting the electron emission source (cathode) 4 is installed in the lower part of the glass container 1 by a support base made of an insulating material fixed to a socket. A cathode lead pin for applying a voltage is electrically connected to the metal substrate 2.

  Here, glass, ceramics, and the like can be used as the insulating material of the support base. For example, forsterite, white plate / potassium glass, blue plate / soda glass, and the like can be used. Moreover, the metal substrate 2 installed on a support stand can use the wiring material which can be used for a semiconductor chip etc. Examples thereof include titanium (Ti), tungsten (W), molybdenum (Mo), iron (Fe), copper (Cu), nickel (Ni), and alloys and compounds thereof.

  As the electron emission source 3, any material can be used as long as it can be formed on the surface of the planar, spherical or hemispherical metal substrate 2 and easily emits electrons. Examples of such materials include carbon-based electron emission materials such as carbon nanotubes, diamond-like carbon (DLC), single crystal diamond, polycrystalline diamond, amorphous diamond, and amorphous carbon. In particular, carbon nanotubes can be preferably used because the voltage required for electron emission is low and the amount of emitted electrons is large, so that the field electron emission lamp can achieve power saving and high brightness. As the utilization form of the carbon nanotube layer, a carbon nanotube layer having a single-layer structure, a carbon nanotube layer having a coaxial multilayer structure, or the like can be used. In the case where the carbon nanotube layer is formed by the thermal CVD method, the metal substrate 2 is preferably a metal containing iron (Fe).

  As a method for forming the electron emission source 4, a printing method, a dip coating method, an electrodeposition coating method, an electrostatic coating method, a dry method, or the like is used. Among these, as a method for forming the carbon nanotube layer suitable for the present invention on the surface of the metal substrate 2, a dry method is preferable. Here, the dry method refers to laser deposition, resistance heating, plasma, thermal CVD, microwave plasma CVD, electron beam deposition, etc., mainly forming carbon nanotubes as electron emission sources by vapor phase growth. How to do. Preferably, a dry method in which a reaction gas is introduced in the presence of an inert gas or hydrogen gas, more preferably, carbon monoxide is introduced in the presence of hydrogen gas, and a thermally decomposed component is converted from a metal containing iron (Fe). A method of depositing carbon nanotubes on the surface of the metal substrate 2 is preferable. Further, by forming carbon nanotubes directly on the metal substrate 2, a smooth coating can be formed on the surface of the metal plate. Therefore, when an electric field is uniformly applied to the surface, electrons are emitted uniformly at each location, so that unevenness in luminance can be prevented.

  The electron extraction electrode (grid electrode) 5 is an electrode for extracting electrons from the electron emission source 4 and is composed of a metal net, a thin metal plate having an opening, etc., and the electrons extracted from the electron emission source 4 reach the phosphor 7. It is formed in a shape that can be made. As a material of the electron extraction electrode 5, 426 alloy, stainless steel (SUS304), invar, super invar, nickel (Ni), or the like can be suitably used. Further, the shape of the electron extraction electrode 5 has a plurality of openings, and is arranged at a predetermined distance from the electron emission source 4 according to the planar shape or spherical shape of the electron emission source 4. The opening of the electron extraction electrode 5 can be formed by etching a thin metal plate or the like, and its planar shape is a circle or a rectangle in which the electric field strength distribution is uniform with respect to the electrons extracted from the electron emission source 4. In addition, an insulating layer can be formed on the surface of the electron extraction electrode 5 facing the electron emission source 4 in order to suppress the reactive current absorbed by the electron extraction electrode 5 and efficiently apply an electric field (not shown). ). As an insulating layer, it is a thin film which can hold | maintain the shape of the electron extraction electrode 5, and the metal compound thin film etc. which are formed by the sputtering method can be used. The electron extraction electrode 5 is preferably fixed to the support using a fixing frit glass and a heat resistant conductive paste. By using both of these, the electron extraction electrode 5 can be fixed and the lead pins for the electron extraction electrode 5 can be electrically connected simultaneously.

  In the configuration as described above, a voltage is supplied from an external circuit to the metal substrate 2 and the electron extraction electrode 5 via a lead pin, an electric field is applied between the metal substrate 2 and the electron extraction electrode 5, and electrons such as a carbon nanotube layer are formed. Extract electrons from source 3. At this time, by supplying a high voltage to the anode-side metal back film 6 through the lead pins, electrons emitted from the electron source 3 collide with the anode-side phosphor layer 7 and correspond to each phosphor. It emits light with a different emission color.

  Since the field electron emission lamp of the present invention has an electromagnetic lens, the traveling direction of the electron beam can be made constant. As a result, it is possible to increase the electron density on the light emitting surface to increase the brightness and obtain a uniform light emitting surface. Further, by converging the electron beam, it is possible to concentrate the electron beam at one point to increase the luminance. Alternatively, since electrons can collide with substantially the entire region of the phosphor layer on the inner surface of the luminous container, a field electron emission lamp free from luminance unevenness can be obtained.

  Furthermore, since the voltage required for electron emission is low and the amount of emitted electrons is large, it is possible to achieve high brightness sufficient for power saving and illumination use. In addition, since a field emission type cathode is used, the handling and manufacture thereof become easy, such as the need for a heating power source is eliminated, the response speed can be improved, and the life of the field electron emission type lamp is greatly prolonged.

  Thus, the field emission lamp of the present invention is used in various fields.

Sectional drawing which shows one Example of the field electron emission type | mold lamp of this invention. Sectional drawing which shows an example of the conventional field electron emission type | mold lamp. Sectional drawing which shows the other example of the conventional field electron emission type | mold lamp.

Explanation of symbols

1: glass container, 2: metal substrate, 3: electron source, 4: electron emission source (cathode), 5: electron extraction electrode (grid electrode), 6: metal back film (anode), 7: electron beam excited phosphor Layer 8: Electromagnetic lens (electromagnetic filter).

Claims (7)

  A light emitting container having a metal back film (anode) having an electron beam-excited phosphor layer formed on the inner surface and evacuated inside, and an electron emission source (cathode) formed on the cathode inside the light emitting container and an electron extraction A field electron emission lamp comprising an electrode (grid electrode), comprising an electromagnetic lens (electromagnetic filter) for converging an extracted electron beam.   2. The field electron emission lamp according to claim 1, wherein the electromagnetic lens is disposed between the metal back film (anode) and the electron extraction electrode (grid electrode).   3. The field electron emission lamp according to claim 1, wherein the electron emission source (cathode) is planar.   4. The field electron emission lamp according to claim 1, wherein the electron emission source (cathode) is a conductive material or a semiconductor material.   The field electron emission lamp according to any one of claims 1 to 4, wherein the electron emission source (cathode) is a carbon nanotube layer or a carbon nanofiber layer.   6. The field electron emission lamp according to claim 1, wherein the metal back film (anode) having the electron beam-excited phosphor layer is a flat surface, and the light emitting container is a box shape.   6. The field electron emission type according to claim 1, wherein the metal back film (anode) having the electron beam-excited phosphor layer is a curved surface, and the luminous container is spherical or hemispherical. lamp.

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