JP2006190544A - Field-emission light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent early deterioration of a phosphor by quickly radiating its heat and enable to uniformalize emission luminance of a whole light-emitting face. <P>SOLUTION: The field-emission light source is so structured that the phosphor 14 and an anode 12 are overlapped on each other in an inner face of a light-emitting panel 10a, a field-emission cathode 16 is arranged at an interval with the anode 12, and linear conductive members 20 are arranged on the phosphor 14 in stripes or in matrix. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a field emission light source that emits electrons to a phosphor and emits light by excitation. In particular, a phosphor and an anode are provided on the inner surface of a light-emitting panel, and the field emission type is spaced apart from the anode. And a field emission type light source in which an electrically conductive member is disposed around a phosphor for heat dissipation and discharge.

  In this type of field emission light source, a planar anode with a phosphor and a cathode that emits electrons across the entire anode surface of the anode are arranged opposite to each other, and a grid that draws electrons from the cathode is interposed therebetween. In other words, the electrons that pass through the grid are accelerated and collided with the phosphor to cause the phosphor to excite and emit light (see Patent Document 1, etc.). In the light emission of the phosphor, the phosphor generates heat as a result of the energy obtained by removing the light emission energy from the acceleration energy of the electrons being applied to the phosphor. This heat generation increases as the anode area increases.

In general, the luminous efficiency of a phosphor tends to decrease with increasing temperature of the phosphor, and the phosphor tends to deteriorate due to heat generation. Thus, techniques for radiating heat for this heat generation have been proposed (see Patent Documents 2, 3, 4, etc.). However, with such existing heat dissipation technology, it takes a considerable time for the heat generation of the entire phosphor to be dissipated, and the life of the phosphor due to heat generation has come early because of a slow heat dissipation rate. In addition, there is unevenness in the heat dissipation of the phosphor, and the luminous efficiency differs in each part of the phosphor, which is a cause of uneven brightness.
Japanese Patent Laid-Open No. 05-251021 JP 2000-173550 A JP 2000-208077 A JP 2003-237126 A

  The present invention enables the heat generation of the phosphor to dissipate heat earlier than before, thereby improving the life of the phosphor by deteriorating the phosphor early, and uniforming the luminous efficiency over the entire phosphor to eliminate uneven brightness, It is an object to provide a field emission type light source having excellent emission characteristics.

  The field emission type light source according to the present invention is a field emission type light source in which a phosphor and an anode are provided in a planar shape on the inner surface of a light emitting panel, and a field emission type cathode is disposed at a distance from the anode. The linear electric conductive member is arranged in a stripe shape or a matrix shape on almost the entire body. The stripe shape is a form in which linear electric conductive members are arranged in one direction such as a vertical direction, a horizontal direction, an oblique direction, and the matrix form is a form in which linear electric conductive members are arranged in two directions including the vertical and horizontal directions. is there. The linear shape includes a linear shape, a curved shape, a meandering shape, and the like. The cross-sectional shape of the linear electrical conductive member is not limited, but includes all of circular, elliptical, rectangular, semicircular, semielliptical, and the like. The anode includes both metal back and metal front forms. In the case of a metal back, a metal that can pass electrons and can reflect light emitted from the phosphor toward the light emitting panel is preferable. In the case of a metal front, a metal such as ITO that can pass fluorescent light emission is preferable. The kind of phosphor is not limited.

  According to the field emission light source, since the linear electric conductive members are arranged in a stripe shape or a matrix shape on the phosphor, a line in which electrons existing at any position of the phosphor are arranged at the closest position. As a result, the heat generated in the phosphor accompanying light emission from the phosphor can be quickly dissipated to the outside of the phosphor. It becomes possible, the fall of the luminous efficiency accompanying the heat_generation | fever of fluorescent substance, deterioration can be suppressed, and the lifetime can be improved. In addition, as a result of the heat generated from the entire phosphor being radiated at an early stage, the luminous efficiency of the entire phosphor can be made uniform, and uneven emission can be suppressed.

  In addition, according to the field emission type light source, not only heat dissipation but also the charge charged in the phosphor can be released to the outside (discharge), thereby allowing the electron beam to enter the phosphor, Luminous efficiency is improved.

  It is preferable to increase the thickness of the linear electric conductive member closer to the periphery of the phosphor. In such a case, the passage of electrons is performed smoothly, and the heat dissipation state throughout the phosphor can be improved.

  The material of the linear electrically conductive member is preferably a metal such as iron, copper, aluminum, magnesium alloy, and aluminum nitride, which has a low resistance in terms of electron transfer speed. As the linear electrically conductive member, an electrically conductive member such as aluminum-impregnated carbon, a composite carbon material of graphite and amorphous carbon, expanded graphite, and a graphite sintered body can be used. The linear electrically conductive member can be made of a fibrous material. In the fibrous electrical conductive member, either short fibers or long fibers can be used, but long fibers are preferably used rather than short fibers because heat can be easily transferred to the heat radiator. The electrically conductive member may be a sheet or may be a sheet in the form of a nonwoven fabric, a woven fabric, a knitted fabric or the like.

  The line width of the linear electrically conductive member is preferably an invisible line width, for example, 100 μm or less. The arrangement interval of the linear electrically conductive members is not particularly limited, and for example, an arrangement interval that can be printed is preferable. However, when printing is performed by a photolithography technique in a semiconductor manufacturing technique, the arrangement interval is appropriately set as long as the printing accuracy permits. The arrangement interval can be selected. In the case of a metal back, the linear electrically conductive member is preferably the front surface of the phosphor, but may be inside the phosphor. In the case of a metal front, the back surface of the phosphor is preferable, but it may be inside the phosphor. The field emission light source can be applied to backlights for liquid crystal display devices, illumination lamps, and other applications.

  ADVANTAGE OF THE INVENTION According to this invention, the heat_generation | fever of fluorescent substance can be thermally radiated earlier than before, and the early deterioration of fluorescent substance can be prevented.

Hereinafter, a field emission light source (referred to as a “light source”) according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 is a cross-sectional view of the light source, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, FIG. 3 is a perspective view showing the front panel, the anode, and the phosphor separately, and FIG. FIG. In these drawings, the present light source has a vacuum vessel 10 having a predetermined vacuum pressure inside. The shape of the vacuum vessel 10 can take various forms depending on the use of a light source including a backlight. In the embodiment, a relatively flat box shape is used for convenience of explanation. The vacuum vessel 10 includes a front panel 10a, a back panel 10b, and a spacer panel 10c. The front panel 10a includes a glass substrate such as quartz or sapphire, and can irradiate light source light to the outside. A planar anode 12 is formed on the inner surface of the front panel 10a in a thin film by sputtering, EB vapor deposition, or the like, such as ITO (indium oxide / tin) or aluminum. The member thickness of the anode 12 is appropriately set depending on the resistivity of the metal material used. The material of the anode may be either ITO or aluminum in the type in which the fluorescence emission is directly seen (direct view type), but it is preferable to use ITO in the transmission type in which the fluorescence emission is seen through the anode. In the direct view type, there is no particular limitation on the material, but examples include inorganic materials such as indium oxide, tin oxide, zinc oxide, zinc chalcogenide, gallium nitride, indium nitride, and CdTe in addition to the above indium oxide and tin. it can. However, when the electron velocity is high, electrons can pass through aluminum, so that either a transmissive type or ITO or aluminum may be used. The electrical resistivity of the anode may be 10 ⁴ ohm cm or less, and does not need to be extremely low resistance.

  The phosphor 14 is formed in a planar shape by being applied to the anode 12 by a slurry application method, an electric perturbation method, a sedimentation method, or the like. A known material (fluorescent material) can be used as the material of the phosphor 14. The thickness of the phosphor 14 is set to about 1 to 5 times the particle size of the phosphor material. It is preferable that the phosphor 14 can emit light with high efficiency by electron beam excitation. The fluorescent material is preferably a material that does not easily react with the conductive material. For example, there is a rare earth oxide fluorescent material. The average particle diameter of the fluorescent particles constituting the phosphor 14 is preferably a value that contributes to the improvement of the light emission efficiency with less unevenness on the fluorescent screen and less uneven light emission.

  The cathode 16 is arranged to extend in a wire shape in one direction at a distance from the anode 12. The cathode 16 is a field emission type cathode that emits electrons so as to cover the entire planar area of the anode 12 by an electric field generated between the anode 12 and the anode 12 by applying an anode voltage of about 10 to 15 kV. The cathode 16 is formed by a conductive wire 16a and a carbon thin film 16b having a number of nanotube-shaped or nanowall-shaped fine protrusions formed on the surface of the conductive wire 16a. In this case, a carbon compound can also be implemented. The cathode 16 may have a configuration in which one or a plurality of conductors are meandered and bent so as to cover the entire planar area of the anode 12 or the grid 18, or the entire planar area of the anode 12 or the grid 18 may be combined with the plurality of conductors. The structure which covers may be sufficient. The conducting wire 16a is made of nickel or an alloy thereof. The carbon thin film 16b has nanotube-like or nanowall-like fine protrusions. The nanowall-like carbon thin film can be formed by a plasma CVD method, for example, an electron cyclotron resonance method (ECR-PCVD method).

  The cathode 16 is positively set to have a surface roughness that makes it easier for the surface of the conductive wire 16a to generate electric field concentration, and the surface roughness irregularities 16c are further formed on the fine protrusions of the carbon thin film 16b only. 16d is formed and acts as an electric field concentration assisting part that promotes electric field concentration at the fine protrusions. This surface roughness is microscopic but may be visible irregularities. For example, the unevenness | corrugation which twists several conducting wires and the unevenness | corrugation which carries out the threading process of the conducting wire surface may be sufficient.

  The grid 18 is in the form of a tube interposed around the cathode 16, and a positive voltage is applied to the cathode 16 to extract electrons from the cathode 16. The grid 18 has a large number of electron passage holes through which electrons pass. ing. The material of the grid 18 is a known metal, and can be appropriately set from the metal. The grid 18 is not necessarily essential.

  In the present light source having the above configuration, the linear electric conductive members 20 are arranged in a matrix on the entire back surface of the phosphor 14. All the linear electric conductive members 20 are connected to each other. The linear electrically conductive member 22 is made of, for example, aluminum. For example, as shown in FIG. 5, electrons in the heat generation point G1 of the phosphor 14 move to the peripheral side with the path indicated by the solid line L1 as the shortest path, and electrons in the heat generation point G2 have the path indicated by the solid line L2 as the shortest path. Move to the peripheral side. As described above, electrons at any position of the phosphor 14 can move along the shortest heat radiation path among the heat radiation paths formed by the linear electric conductive members 22 arranged in a matrix. The wire diameter of the linear electrically conductive member 22 is preferably 100 μm or less because it is invisible. The arrangement interval of the linear electric conductive members 22 is not limited as long as printing is possible. The arrangement interval of the linear electric conductive members 22 can be further reduced when using a photolithography technique in a semiconductor manufacturing process.

  As described above, in the field emission type light source of the embodiment, the heat generated by the light emission of the phosphor 14 is radiated through the shortest path via the linear electric conductive member 20, so that the luminous efficiency associated with the heat generation of the phosphor 14 is improved. Thus, it is possible to prevent a decrease, deterioration, and the like, and it is possible to contribute to the improvement of the life of the phosphor 14 and the elimination of uneven emission of the field emission light source.

Linear electrically conductive member 22, as shown in Figure 6, the thinnest member thickness linear electrical conductive members 20 ₁ in the farthest region Z1 which is the farthest from the peripheral edge including a rear center of the phosphor 14, the then first the member thickness of the linear electrically conductive member 20 ₂ of the intermediate region Z2 thick is farther, thicker members thickness of the linear electrically conductive element 20 ₃ of the second intermediate region Z3 approaching the periphery , and thickest member thickness linear electrical conductive members 20 ₄ closest region Z4 the periphery. The electrons of the phosphor 14 gather from the periphery and increase in quantity as they approach the periphery, but the thickness of the member gradually increases, so that the electrons move smoothly through the linear electrical conductive member 20. Can do. Therefore, heat dissipation of the entire phosphor 14 is performed smoothly.

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

It is sectional drawing of the field emission type light source which concerns on embodiment of this invention. It is sectional drawing of the AA line of FIG. It is a perspective view which isolate | separates and shows the front panel, anode, and fluorescent substance of FIG. It is a rear view of the fluorescent substance which shows arrangement | positioning of a linear electrically conductive member. It is a principal part rear view of the fluorescent substance for demonstrating the movement path | route of the electron with respect to a linear electrically conductive member. It is the rear view (a) and sectional drawing (b) of the fluorescent substance which show the other structural example of a linear electrically conductive member.

Explanation of symbols

12 Anode 14 Phosphor 16 Cathode 18 Grid 20 Linearly Conductive Member

Claims (3)

  In a field emission type light source in which a phosphor and an anode are provided on the inner surface of a light emitting panel so as to overlap each other, and a field emission type cathode is disposed at a distance from the anode, linear electric conduction is performed on almost the entire phosphor. A field emission type light source characterized in that members are arranged in a stripe or matrix form.   2. The field emission type light source according to claim 1, wherein a member thickness of the linear electric conductive member on the phosphor is made thicker on the phosphor peripheral side than on the phosphor central side. 3. The field emission light source according to claim 1, wherein the line width of the linear electric conductive member is an invisible line width.

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