JP2007012458A - Cold cathode fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve initial total luminous flux as a fluorescent lamp by coating a part of a surface of a phosphor particle which is a material for a phosphor film with metal compound fine particles. <P>SOLUTION: In this cold cathode fluorescent lamp, mercury and one or more kinds of rare gas are sealed in a glass tube 1, a pair of discharging electrodes 4 are provided at ends of the glass tube through the sealing wire 3, and the phosphor film 2 is formed from the phosphor particles 11 wherein the surfaces are coated with the metal compound 12 in an inner wall of the glass tube. The coating area of the metal compound 12 is set 10 to 40% to the surface area of the phosphor particles 11. Thereby, mercury adsorption to the phosphor is prevented with the coating of the part of the metal compound on the surface of the phosphor particle, and the initial total luminous flux can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cold cathode fluorescent lamp.

  A cold cathode fluorescent lamp used as a light source for a backlight of a liquid crystal display has a configuration shown in FIGS. FIG. 5 is a longitudinal sectional view of a conventional cold cathode fluorescent lamp, and FIG. 6 is a sectional view in a circular state. One or more kinds of mercury and rare gas are sealed inside the glass tube 1, and a pair of discharge electrodes 4 are installed inside both ends via sealing wires 3. Further, a phosphor coating 2 is formed on the inner wall of the glass tube 1 with a thickness of about 10 to 40 μm. A three-wavelength phosphor mainly composed of red, green, and blue is used for the phosphor that is a material of the phosphor coating 2.

  Phosphors deteriorate in lamp life characteristics such as a reduction in total luminous flux due to mercury adsorption during the life of the cold cathode lamp. In order to improve this, until now, it has been improved by a method in which a metal compound is coated on almost the entire surface of the phosphor particles.

However, when the phosphor particles are coated with a metal compound, there is a problem that the initial total luminous flux of the fluorescent lamp decreases. Conventionally, the amount of the metal compound coated on the phosphor particle surface is determined by the weight ratio to the phosphor, but in this method, the area coated on the phosphor particle surface varies depending on the specific gravity of the metal compound used. There was also a problem that would do.
JP 2004-182907 A

  The present invention has been made in view of the above-mentioned problems of the prior art, and since the total luminous flux of the phosphor is determined by the area of the phosphor particle surface, it is not the weight ratio of the metal compound to the phosphor. An object of the present invention is to provide a cold cathode fluorescent lamp in which the area to be covered is adjusted and the initial total luminous flux as a fluorescent lamp is improved.

  In the present invention, one or more kinds of mercury and rare gas are sealed inside the glass tube, and a pair of discharge electrodes are installed inside the both ends of the glass tube via sealing wires. A cold cathode fluorescent lamp having a phosphor film formed of phosphor particles coated with a metal compound on the surface, wherein the metal compound has a coat area of 10 to 40% with respect to the surface area of the phosphor particles. It is characterized by.

  In the cold cathode fluorescent lamp of the present invention, the metal compound having a particle size of 0.1 μm to 0.2 μm can be adopted.

  In the cold cathode fluorescent lamp of the present invention, the surface of the phosphor particles can be coated in a state where some of the particles of the metal compound are aggregated and unevenly distributed.

  According to the present invention, it is possible to prevent mercury adsorption on the phosphor by coating a part of the phosphor particle surface with the metal compound and to improve the initial total luminous flux.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The cold cathode fluorescent lamp of the present embodiment has the structure shown in FIGS. 5 and 6 as in the prior art. The metal compound fine particles, particularly La (lanthanum) or Y (yttria), Al (aluminum), on a part of the surface of the phosphor particles used as the material of the phosphor film 2 or on a part of the surface of the phosphor film 2. Coating prevents mercury from adsorbing to the phosphor, increases the initial total luminous flux of the fluorescent lamp, and improves the lamp life characteristics.

FIGS. 1 and 2 are explanatory views of coating the surface of the phosphor particles 11 with La fine particles 12, FIG. 1 is a top view, and FIG. 2 is a side view. In the cold cathode fluorescent lamp of the present embodiment, the red phosphor (Y ₂ O ₃ : Eu), the green phosphor (LaPO ₄ : Ce, Tb), and the blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), respectively. The La fine particles 12 are coated in a range not exceeding 70% by weight. The phosphor is applied to the inside of the glass tube 1 by adding phosphor slurry in which a phosphor is dispersed in an inorganic binder in which a thickener such as polyethylene oxide is dissolved in water, or a thickener such as nitrocellulose in butyl acetate. A phosphor slurry in which a phosphor is dispersed in a dissolved organic binder is used. And after apply | coating, the fluorescent substance film 2 is formed by making it dry. The film thickness of the coating is 10 to 40 μmw as in the conventional case.

  According to the cold cathode fluorescent lamp of the present embodiment, the metal compound fine particles 12 are coated on part of the surface of the phosphor particles 11 used in the phosphor coating 2, thereby preventing mercury adsorption on the phosphor. As a fluorescent lamp, the initial total luminous flux can be improved, and the lamp life characteristics of the cold cathode fluorescent lamp can be improved.

  A phosphor film was applied and formed using an organic binder, and lamp characteristics were measured. For comparison of characteristics, the coating of the metal compound La fine particles on the phosphor was performed between 0% and 100% in steps of 10% with respect to the surface of the phosphor particles. The shape of the cold cathode fluorescent lamp is the same as that of the conventional type shown in FIGS. 5 and 6, and is formed by applying the phosphor coating 2 using an organic binder. The specifications of the fluorescent lamp are as follows. Glass tube inner diameter: φ2.0 mm, lamp length: 350 mm, and tube current was 6 mArms.

  In the experiment, the total luminous flux maintenance factor was measured with respect to the relative total luminous flux at the initial stage of 0 Hr and the initial total luminous flux after 2000 hours of life for each La coat area of the cold cathode fluorescent lamp. FIG. 3 shows the measurement result of the relative total luminous flux at the initial stage of 0 Hr for each La coat area, and FIG. 4 shows the measurement result of the total luminous flux maintenance ratio compared with the initial total luminous flux after 2000 Hr life. As shown in FIGS. 3 and 4, the initial relative total luminous flux decreased as the coating area of the metal compound on the phosphor particles increased, but the total luminous flux maintenance factor after 2000 Hr was improved. When the coat area was in the range of 10 to 40%, the decrease in the initial relative total luminous flux was suppressed to 3% or less, and the total luminous flux maintenance factor after 2000 Hr was 90% or more. From this, it was confirmed that the life characteristics of the lamp can be improved by the present invention.

The top view of the state which coat | covered La microparticles | fine-particles on the surface of the fluorescent substance particle of one embodiment of this invention. The side view of the state which coat | covered the La microparticles | fine-particles on the surface of the fluorescent substance particle of one embodiment of this invention. The graph which shows the relative total light beam at the time of initial stage 0Hr of the Example of this invention. The graph which shows the total luminous flux maintenance factor after 2000 Hr lifetime of the Example of this invention. 1 is a longitudinal sectional view of a general cold cathode fluorescent lamp. Sectional drawing of a general cold cathode fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass tube 2 Phosphor film 4 Electrode 11 Phosphor particle 12 La fine particle

Claims (3)

One or more kinds of mercury and rare gas are sealed inside the glass tube, a pair of discharge electrodes are installed inside the glass tube via sealing wires, and the inner surface of the glass tube has a metal compound on its surface. A cold cathode fluorescent lamp in which a phosphor film is formed by phosphor particles coated with
The cold cathode fluorescent lamp, wherein the metal compound has a coating area of 10 to 40% with respect to a surface area of the phosphor particles.   The cold cathode fluorescent lamp according to claim 1, wherein a particle diameter of the metal compound is 0.1 µm to 0.2 µm. 3. The cold cathode fluorescent lamp according to claim 1, wherein a surface of the phosphor particles is coated in a state where some of the particles of the metal compound are aggregated and unevenly distributed.

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