JP2008084660A - Field emission lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow uniform light emission by entirely suppressing flickering in light emission from a phosphor layer even if a planar phosphor layer receives electron ray radiation at a plurality of different points from a plurality of electron emitting points which a field radiation negative electrode has. <P>SOLUTION: A field emission lamp 10 comprises a phosphor layer 18 which excites light emission under the electron ray radiation from inside, and a light scattering layer 24 which scatters the light outside the phosphor layer 18. The phosphor layer 18 is formed on the inner surface of an inside lamp tube 12, and the light scattering layer 24 is formed on the inner surface of an outside lamp tube 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a field emission lamp in which an anode layer with a phosphor layer is formed on the inner surface of a lamp tube, and a field emission cathode is disposed in the lamp tube so as to face the anode layer.

  In the field emission lamp, a positive voltage of a DC power source is applied to the anode layer side, and electrons are emitted from each of a large number of electron emission points on the field emission cathode toward the anode layer by electric field concentration, and the emitted electrons are discharged. The phosphor layer is excited to emit light by colliding with an electron beam excitation type phosphor layer on the anode layer surface (Patent Document 1).

  In such a driving method, as indicated by d 1 → d 2 → d 3 → in FIG. 9, the areas indicated by the bright white circles that have been excited and emitted until then correspond to the light emitting areas of the phosphor layer are darkened. The region indicated by another black circle that has been dark until then is excited to emit light and become brighter.

  In the conventional driving method, light and dark flickering, that is, a light emission state consisting of a set of many light and dark spots indicated by white and black as described above, where the light and dark spots are not determined, and the light emission state changes in a complex and random manner. Was.

  In addition, the presence of dark areas also affects the magnitude of luminance. Furthermore, energy that does not contribute to light emission changes to heat, and the temperature of the field emission lamp becomes extremely high, making the field emission lamp difficult to handle and large energy loss.

  Therefore, in order to prevent such charge-up, for example, it is conceivable to provide a thin film sheet of aluminum on the inner surface of the phosphor layer by vapor deposition of aluminum and prevent charge-up by this thin film sheet. Therefore, it takes time to relieve the charge-up, and during that time, electrons cannot be emitted to emit light toward each region of the phosphor layer, so that flickering of light emission cannot be sufficiently suppressed. In particular, when the tube diameter of a field emission lamp becomes an ultrathin tube of about several millimeters, such aluminum vapor deposition is difficult and it is difficult to manufacture the field emission lamp.

In addition, when the field emission lamp has a tube diameter of about 1 mm around the inside of the glass tube in a non-contact state with the inner surface of the glass tube and a field emission cathode is installed in the air in the longitudinal direction, The field emission cathode is attracted and brought into contact with the anode layer side by Coulomb force.
JP 2000-090852 A

  The problem to be solved by the present invention is that the phosphor layer facing the plurality of electron emission points provided in the field emission cathode is irradiated with electron beams at a plurality of different positions from the plurality of electron emission points. In a light emission form in which excitation light is emitted at each of a plurality of locations, light emission flickering of the entire phosphor layer can be suppressed and light can be emitted uniformly in a planar shape.

  In the field emission lamp according to the first aspect of the present invention, one side of the phosphor layer is disposed in a plane so as to face a plurality of electron emission points, and the phosphor layer is irradiated with an electron beam from each electron emission point at a plurality of locations. In the field emission lamp that emits excitation light, a light scattering layer is provided in a planar shape on the other side of the phosphor layer.

  The light scattering layer is not limited to the material as long as it can scatter light.

  The phosphor layer is not limited to the type of light that is excited by electron beam irradiation to emit light. For example, visible light or ultraviolet light may be used.

  Regarding the light scattering layer, Japanese Patent Application Laid-Open No. 2002-267812 discloses a light scattering layer containing a transparent resin and a scattering material. Japanese Patent Laid-Open No. 2001-124908 discloses a light scattering layer as a transparent resin layer containing dispersed fine particles.

  In the above, it is not limited to the number of phosphor layers or light scattering layers.

  In the first aspect of the present invention, even if light emission from the phosphor layer has light and dark flickering, the light emission is scattered and diffused by the light scattering layer. A field emission lamp can be obtained.

  This field emission lamp is not limited to its application.

  The phosphor layer is preferably made of a phosphor that excites and emits visible light or ultraviolet light by electron beam irradiation.

  The light scattering layer is preferably composed of a phosphor layer that excites and emits visible light when irradiated with ultraviolet light.

  A preferred embodiment of the present invention is that the light scattering layer is directly laminated on the other side of the phosphor layer in a planar shape or disposed so as to face the surface in a spaced manner.

  A first preferred embodiment of the present invention is that the light scattering layer includes a plurality of fine particles having light scattering properties. The fine particles preferably have translucency. The particle size of the fine particles is not particularly limited, but a larger particle size is preferable. For example, the particle size can be in the range of 10 μm to several tens of μm. It is conceivable that the light scattering layer is composed of several layers by these fine particles.

  A first preferred embodiment of the present invention includes a pair of lamp tubes arranged in an inner / outer double tube configuration, and the inner lamp tube is vacuum-sealed, and the phosphor layer is provided on the inner surface together with the anode layer. In addition, a field emission cathode having a number of electron emission points on the outer peripheral surface is provided at the center of the tube, and the outer lamp tube is provided with the light scattering layer on the inner surface. is there.

  A first preferred embodiment of the present invention includes a lamp tube having a single tube structure, and the lamp tube is vacuum-sealed, and a phosphor layer, a light scattering layer, and an anode layer are formed on the inner surface from the inner diameter side to the outer diameter side. In addition to being laminated in this order, a field emission cathode provided in the shape of a wire and having a large number of electron emission points on the outer peripheral surface is provided at the center of the tube.

  A first preferred embodiment of the present invention includes a lamp tube having a single tube structure, and the lamp tube is vacuum-sealed, and a phosphor layer and an anode layer are laminated on the inner surface thereof, and at the center of the tube. A field emission cathode extending in a wire shape and having a large number of electron emission points on its outer peripheral surface is provided, and the light scattering layer is provided in the form of a sheet on the outer surface of the lamp tube.

  A light scattering sheet is disclosed in, for example, JP-A-2002-250806. In this publication, the light scattering sheet is composed of a plurality of polymers having different refractive indexes, and at least a light scattering layer having a droplet phase structure. Japanese Unexamined Patent Publication No. 2000-258612 discloses a light scattering sheet having a light forward scattering functional layer in which organic fine particles and / or inorganic fine particles are dispersed in a transparent resin base. Japanese Patent Application Laid-Open No. 2000-241609 discloses that a thermoplastic resin or fine particles are dispersed in a thermoplastic transparent resin base by melt film formation, the thickness is 30 to 300 μm, and the total light transmittance of optical characteristics is 85. And a haze value in the range of 10 to 80%, and a light scattering sheet having a forward scattering function manufactured by melt film formation is disclosed.

  A field emission lamp according to a second aspect of the present invention includes a single-tube lamp tube, and a phosphor layer for exciting and emitting light by electron beam irradiation is provided on the inner surface of the lamp tube. The light-scattering powder which scatters the said light is mixed with the fluorescent substance powder which comprises it, It is characterized by the above-mentioned.

  According to the present invention, the light scattering layer that scatters the light is arranged outside the phosphor layer that excites and emits light by electron beam irradiation from the inside. It becomes possible to emit light uniformly.

  Hereinafter, a field emission lamp according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1A is a side cross-sectional view of a field emission lamp, FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 2 is a schematic enlarged view of the main part of FIG. Sectional drawing and FIG. 3 are the figures which expand further and show the principal part of FIG. 2 typically.

  Referring to FIG. 1, reference numeral 10 denotes a field emission lamp. The field emission lamp 10 includes inner and outer double lamp tubes 12 and 14 and a field emission cathode 16.

  2 and 3, the inner lamp tube 12 includes a vacuum layer 13 whose inside is vacuum-sealed. On the inner surface of the inner lamp tube 12, a phosphor layer 18 and an anode layer 20 are laminated in a planar shape. A field emission cathode 16 extending in the shape of a wire in the longitudinal direction is disposed inside the inner lamp tube 12 so as to face the anode layer 20.

  The anode layer 20 is formed as a thin film of a metal such as ITO (indium oxide / tin) or aluminum by sputtering or EB vapor deposition.

  The phosphor layer 18 is an electron beam excited phosphor that emits light when excited by electron beam irradiation. The phosphor layer 18 is excited to emit visible light when irradiated with an electron beam from the field emission cathode 16. The phosphor layer 18 may be a known electron beam excited phosphor, and is not particularly limited.

  The field emission cathode 16 extends in the shape of a wire in the longitudinal direction of the inner lamp tube 12 at the approximate center of the inner lamp tube 12. The field emission cathode 16 is formed by forming a carbon film having a number of fine protrusions on the order of nm as electron emission points on the outer periphery of a conducting wire. The carbon film is, for example, a carbon nanotube, a carbon nanowall, a needle-like carbon film, or the like, and emits electrons by electric field concentration at the tip of a fine protrusion.

  The shape of the field emission lamp 10 can take various forms depending on the use of the light source including the backlight, and is not limited to the narrow tube shape as in the embodiment, Other shapes can be used.

  The outer lamp tube 14 is provided so as to cover the outer periphery of the inner lamp tube 12 with an air layer 22 interposed therebetween. A light scattering layer 24 is formed on the inner surface of the outer lamp tube 14. However, the inclusion between the inner lamp tube 12 and the outer lamp tube 14 is not limited to the air layer 22. The air layer 22 is not necessarily required. The phosphor layer 18 and the light scattering layer 24 face each other with the air layer 22 therebetween, that is, face each other with a space therebetween.

  The light scattering layer 24 includes a plurality of fine particles 24 a having a particle size of 10 μm to several tens of μm and having light transmission properties. The light scattering layer 24 can be composed only of the fine particles 24a. As shown in FIG. 3, the light scattering layer 24 may have a structure in which the fine particles 24 a are dispersed in several layers in the translucent resin 24 b. The fine particles 24a include inorganic powders such as silica powder. The fine particles 24a can be formed of ultraviolet light-excited luminescent phosphor fine particles by irradiation with ultraviolet light.

  The light scattering layer 24 can be formed into a sheet shape. The sheet-like light scattering layer 24 is disclosed in JP-A-6-18706, JP-A-10-20103, JP-A-11-160505, JP-A-11-305010, JP-A-11-326608, JP-A-2000-121809, No. 2000-180611 and 2000-338310 can be mentioned.

  The phosphor layer 18 and the light scattering layer 24 are respectively formed on the inner surfaces of the inner lamp tube 12 and the outer lamp tube 14 by a slurry coating method, a screen printing method, an electric perturbation method, a sedimentation method, or the like.

  The operation of the field emission lamp 10 having the above configuration will be described with reference to FIG. In FIG. 4, the white circles on the outer surface 12a of the inner lamp tube 12 are bright portions P that emit light with bright luminance, and the black circles are dark portions Q that are not emitting light from the light emitting state. Since the bright part P and the dark part Q have been described with reference to FIG. 9, the description thereof will be omitted.

  In the air layer 22 between the inner lamp tube 12 and the outer lamp tube 14, the hatching corresponds to the dark portion Q and no light emission exists. The white space between the hatching in the air layer 22 indicates that the visible light B is traveling substantially straight from the outer surface 12 a of the inner lamp tube 12 toward the light scattering layer 24 on the inner surface of the outer lamp tube 14. Visible light B is considered to travel straight as indicated by the arrows in the figure because the bright part P and dark part Q are visible from the outside of the field emission lamp 10.

  Next, the visible light B that has reached the light scattering layer 24 is scattered by the light scattering layer 24 as shown by the arrows in the figure, and as a result, diffuses until it is emitted from the light scattering layer 24 to the outer lamp tube 14. Visible light B1 can be emitted almost uniformly from the outer lamp tube 14. In addition, the light diffusion of the arrow in the figure is simply shown for understanding, and the light diffusion direction is considered to be more complicated.

  When the outer surface 14a of the outer lamp tube 14 is viewed from the front of the outer lamp tube 14 by the light diffusion, there is no dark portion on the outer surface 14a, and the light emission is uniform over the entire surface. In this case, since the entire outer surface 14a is a bright part and no dark part, the state of the bright part is not shown.

  As for the light scattering in the light scattering layer 24, if the particle size of the scattering fine particles 24a is large, the scattering intensity increases in the entire circumferential direction, and in particular, the scattered light intensity in the forward direction increases. On the other hand, as the particle size becomes smaller, the scattered light intensity is weakened as a whole, and the characteristic strong forward scattered light is weakened. In the embodiment, the particle size of the scattering fine particles 24a can be appropriately set by experiment.

  As a result, the field emission lamp 10 of the embodiment can provide a uniform emission field emission lamp with little or no flicker.

  In the above, as shown in FIG. 5, the phosphor layer 18 on the inner surface of the inner lamp tube 12 is a phosphor that excites the ultraviolet light C by irradiation of the electron beam A, and the light scattering layer 24 on the inner surface of the outer lamp tube 14. Is made of a phosphor that excites and emits visible light when irradiated with ultraviolet light C. By irradiating the light scattering layer 24 with ultraviolet light C from the inner lamp tube 12, the visible light is excited and emitted. It can be emitted as visible light B1 that diffuses inside and does not flicker outward. An example of the phosphor constituting the phosphor layer 18 is a fine powder zinc oxide phosphor.

  As shown in FIG. 6, the above-mentioned odor is not a double-tube structure of the lamp tube, but the outer lamp tube 14 is omitted and a single-tube structure of the single inner lamp tube 12 is formed. The light from the inner lamp tube 12 may be scattered by attaching a transparent light scattering sheet 26 as a light scattering layer to the surface. The light scattering sheet 26 is more likely to cause light scattering by providing fine irregularities on the outer surface. Since the outer lamp tube 14 is omitted, the inner lamp tube 12 simply becomes the lamp tube 12.

  The above-mentioned scattering refers to a light scattering state for making the light emitted from the outer lamp tube 14 come from all directions. In this specification, the meaning of this scattering includes light diffusion. To do.

  In the above case, as shown in FIG. 7, the lamp tube is not configured as a double tube, but the outer lamp tube 14 is omitted, the inner lamp tube 12 is configured as a single tube, and the phosphor layer 18 is formed as an electron beam. It is possible to adopt an inner / outer two-layer configuration in which visible light is excited to emit light on the inner layer side and the light scattering layer 24 is on the outer layer side that diffuses visible light from the phosphor layer 28. Since the outer lamp tube 14 is omitted, the inner lamp tube 12 simply becomes the lamp tube 12. In this case, the phosphor layer 18 and the light scattering layer 24 are directly laminated. In the above description, the phosphor layer 18, the light scattering layer 24, and the anode layer 20 are laminated in this order from the inner diameter side to the outer diameter side of the lamp tube 12.

  In the above case, as shown in FIG. 8, a phosphor layer / light scattering layer 38 is provided by mixing phosphor powder 34 that excites light by electron beam irradiation and phosphor powder 36 that diffuses light. It can be configured.

  The present invention is not limited to the above-described embodiments, and includes various changes or modifications within the scope described in the claims.

FIG. 1A is a side sectional view of a field emission lamp according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA in FIG. FIG. 2 is an enlarged sectional view showing a part of the field emission lamp of FIG. FIG. 3 is a cross-sectional view schematically showing an essential part of FIG. FIG. 4 is a cross-sectional view corresponding to the main part of FIG. 2 for explaining the operation of the field emission lamp of the embodiment. FIG. 5 is an enlarged sectional view showing a part of a field emission lamp according to another embodiment. FIG. 6 is an enlarged sectional view showing a part of a field emission lamp according to still another embodiment. FIG. 7 is an enlarged cross-sectional view showing a part of a field emission lamp according to another embodiment. FIG. 8 is an enlarged sectional view showing a part of a field emission lamp according to still another embodiment. FIG. 9 is a diagram used for explaining the problem of the conventional field emission lamp.

Explanation of symbols

10 Field Emission Lamp 12 Inner Lamp Tube 14 Outer Lamp Tube 16 Field Emission Cathode 18 Phosphor Layer 20 Anode Layer 22 Air Layer 24 Light Scattering Layer A Electron Beam B Visible Light B1 Visible Light C Ultraviolet Light

Claims (7)

One side of the phosphor layer is arranged in a plane to face a plurality of electron emission points, and this phosphor layer is irradiated with an electron beam from each electron emission point and is excited and emitted at a plurality of locations.
A field emission lamp, wherein a light scattering layer is provided in a planar shape on the other side of the phosphor layer.   The field emission lamp according to claim 1, wherein the light scattering layer includes a plurality of fine particles having light scattering properties.   3. The field emission lamp according to claim 1, wherein the light scattering layer is laminated in a planar shape directly on the other side of the phosphor layer or is disposed so as to face the surface at a distance. 4. It has a pair of lamp tubes arranged in an internal / external double tube configuration,
The inner lamp tube is vacuum-sealed, and the phosphor layer is provided on the inner surface together with the anode layer. At the center of the tube, a field emission cathode having a wire shape and having a large number of electron emission points on the outer peripheral surface Is provided,
The outer lamp tube is provided with the light scattering layer on the inner surface thereof,
The field emission lamp according to claim 1, wherein the field emission lamp is provided. It has a lamp tube with a single tube configuration,
The lamp tube is vacuum-sealed, and a phosphor layer, a light scattering layer, and an anode layer are laminated on the inner surface from the inner diameter side to the outer diameter side in this order. The field emission lamp according to claim 1 or 2, wherein a field emission cathode having a large number of electron emission points on a surface thereof is provided. It has a lamp tube with a single tube configuration,
The above-mentioned lamp tube is vacuum-sealed, a phosphor layer and an anode layer are laminated on the inner surface thereof, and a field emission cathode having a plurality of electron emission points on the outer peripheral surface extending in a wire shape at the tube center Is provided,
The field emission lamp according to claim 1, wherein the light scattering layer is formed in a sheet shape and provided on an outer surface of the lamp tube. It has a lamp tube with a single tube configuration,
On the inner surface of the lamp tube, there is provided a phosphor layer that excites and emits light by electron beam irradiation, and this phosphor layer is mixed with light scattering powder that scatters the light into the phosphor powder constituting the phosphor layer. It is a rare field emission lamp.

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