JP2005340066A - Cold cathode fluorescent lamp, manufacturing method of the same, and illumination device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode fluorescent lamp, of which a defect caused by exfoliation of a phosphor layer is reduced. <P>SOLUTION: The cold cathode fluorescent lamp is composed of a frosted layer 11 formed on an inner wall of a glass tube main body 10; a protection film layer 12 formed on the surface of the frosted layer 11 preventing deterioration of the glass tube main body; a phosphor layer 13 formed on the protection film layer; rare gas 16 filled in the glass tube main body 10 on which the phosphor layer 13 is formed; and a pair of electrodes 14 sealed on both ends of the glass tube main body 10 in which the rare gas 16 is filled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cold cathode fluorescent lamp and an illumination device using the same.

  Conventionally, the structure of a cold cathode fluorescent lamp is provided with a pair of electrodes each provided with a phosphor layer on the inner wall surface of a glass tube and sealed at both ends. Inside the glass tube body, a rare gas made of, for example, a mixed gas of neon and argon is sealed as a discharge medium, and both ends are sealed airtight. Further, in a conventional fluorescent lamp, an inner surface protective film layer is also provided in order to prevent blackening or deterioration of a glass tube due to a chemical reaction between a discharge medium such as mercury and glass. That is, as shown in FIGS. 4A and 4B, a protective film 52 made of a metal oxide is formed on the inner surface of the glass tube 51 by coating, and a phosphor layer is further formed on the protective film 52. 53 is formed (see, for example, Patent Document 1 and Patent Document 2).

The cold cathode fluorescent lamp manufactured in this way is also used as a direct type backlight unit of a liquid crystal display device by arranging a plurality of lamps in parallel.
JP 2002-324515 A Japanese Patent Laid-Open No. 11-191389

  However, in the phosphor coating process of the cold cathode fluorescent lamp, a protective film specification in which a protective film is applied to the inner wall of the glass tube and the phosphor is applied, or a long glass tube fluorescent lamp, the glass and protective film layer or phosphor The phosphor peels frequently due to insufficient binding force between the layers.

  Further, in a backlight unit for a liquid crystal display device using these fluorescent lamps, luminance unevenness of each fluorescent lamp occurs, and uniform light emission cannot be obtained.

  The present invention has been made in view of the conventional problems as described above, and has improved the binding force of the protective film layer or the phosphor to the inner wall of the glass tube, thereby reducing the occurrence of defects due to the peeling of the phosphor. Another object of the present invention is to provide a method for manufacturing the same and a lighting device using the same that reduces uneven brightness.

  In order to achieve the above object, a cold cathode fluorescent lamp of the present invention comprises a frosted layer formed on the inner wall of a glass tube, a protective film layer formed on the surface of the frosted layer, A phosphor layer formed on the surface, a rare gas filled in the tube of the glass tube formed with the phosphor layer, and a pair of electrodes sealed at both ends of the glass tube filled with the rare gas, It is characterized by comprising.

  In order to achieve the above object, the cold cathode fluorescent lamp of the present invention comprises a frosted layer formed on the inner wall of a glass tube, a phosphor layer formed on the surface of the frost layer, and the phosphor. It is characterized by comprising a rare gas filled in a tube of the glass tube body in which a layer is formed and a pair of electrodes sealed at both ends of the glass tube filled with the rare gas.

  Furthermore, in the cold cathode fluorescent lamp of the present invention, the frosted layer is formed by a hydrofluoric acid treatment.

  In order to achieve the above object, the manufacturing method of the cold cathode fluorescent lamp of the present invention includes a step of forming a frosted layer on the inner wall of the glass tube and a protective film layer on the surface of the frosted layer. A step of forming a phosphor layer on the surface of the protective film layer, a step of filling a rare gas in the tube of the glass tube on which the phosphor layer is formed, and the glass filled with a rare gas The method includes a step of sealing a pair of electrodes at both ends of the tube.

  In order to achieve the above object, the manufacturing method of the cold cathode fluorescent lamp of the present invention includes a step of forming a frosted layer on the inner wall of the glass tube and a phosphor layer formed on the surface of the frosted layer. A step of filling a rare gas into the tube of the glass tube on which the phosphor layer is formed, and a step of sealing a pair of electrodes at both ends of the glass tube filled with the rare gas. It is characterized by.

  The illumination device of the present invention is characterized in that a plurality of the cold cathode fluorescent lamps are arranged and installed.

  According to the present invention, the phosphor layer can be prevented from being peeled off by the frost processing applied to the inner wall of the glass tube body, particularly compared to a cold cathode fluorescent lamp in which the phosphor layer is formed on the protective film. Thus, it is possible to manufacture a cold cathode fluorescent lamp in which the occurrence rate of phosphor peeling failure is drastically reduced.

  Further, in a surface illumination device such as a backlight unit of a liquid crystal display device in which a plurality of cold cathode fluorescent lamps according to the present invention are arranged in parallel, a frost processing applied to the glass tube allows the glass tube to Since the emitted light is diffused at a wide angle, there is an effect of reducing unevenness in luminance in the arrangement direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings and evaluation results of characteristics.

  In the present embodiment, in the process of processing a glass (borosilicate glass) tube in the manufacture of a cold cathode fluorescent lamp, as shown schematically in FIG. 1 (a), hydrofluoric acid ( The frost layer portion 11 is formed by performing a dissolution treatment by HF). Further, as shown in a cross section in FIG. 2C, a protective film 12 for preventing deterioration such as blackening of the inner wall of the glass tube is formed on the frost layer 11 formed by the frost processing, and the fluorescent film is formed on the protective film 12. The body is applied to form the phosphor layer 13. The glass tube 10 in which the phosphor layer 13 is formed is filled with a rare gas 16, and a pair of electrodes 14 are hermetically sealed 15 at both ends of the glass tube 10. A fluorescent lamp is manufactured. Alternatively, without forming a protective film, a phosphor is directly applied to the frost layer portion 11 to form the phosphor layer 13 to manufacture a cold cathode fluorescent lamp. The same figure (b) shows the example of the microscope picture from the front of the frost layer part 11 formed in the inner wall of this glass tube body 10. FIG. From this micrograph, the surface of the inner wall is formed with unevenness (frost) of about 5 μm by dissolution with hydrofluoric acid. The uneven state formed in the frosted layer portion 11 can be changed by changing the concentration of hydrofluoric acid, the dissolution treatment temperature, the additive conditions, and the like.

Table 1 shows a comparison of the rate of occurrence of phosphor peeling in the case where the frost layer is formed by performing the dissolution treatment with hydrofluoric acid of the present embodiment and in the conventional case where the treatment with hydrofluoric acid is not performed. .

  As shown in Table 1, the crow tube of the test sample on which the phosphor peeling was compared was made with samples 21 and 22 having an outer diameter of 4 mm (inner diameter of φ3.0 mm) and a length of 900 mm, and a thinner outer diameter of φ2.4 mm. Two types of tube diameters of samples 23 and 24 having an inner diameter of 2.0 mm and a length of 350 mm. Further, samples 21 and 23 of the test samples in Table 1 are conventional ones that have not been subjected to frost processing with hydrofluoric acid, and samples 22 and 24 have been subjected to frost processing with hydrofluoric acid of the present invention. In addition to the presence or absence of this frost processing, the combination of the presence or absence of the formation of the inner surface protective film layer was further added to each. That is, the samples 21a and 23a having different tube diameters in which the phosphor layer is directly formed on the inner wall of the glass tube without applying the inner surface protective film layer without applying the conventional frost processing, and the inner surface first on the inner wall of the glass tube The protective film layer is formed, and the phosphor layers are formed on the samples 21b and 23b having different tube diameters. Further, the frost processing of the present invention is applied, and the inner wall subjected to the frost processing without applying the inner surface protective film layer is directly fluorescent. Eight types of samples 22a and 24a with different tube diameters forming body layers, and samples 22b and 24b with different tube diameters formed with an inner surface protective film on the inner wall subjected to frost processing, Each of the 400 samples was used as the reference sample number.

  In addition, the test method for peeling of the phosphor is on a bakelite plate having a thickness of 10 mm, with one end of the lamp (for example, the sealed end where the electrode is first sealed in the lamp manufacturing process) as a fulcrum. , Stand so that the inclination of the lamp is 80 degrees or more, and let the other end (exhaust side end from which the gas in the tube is exhausted in the lamp manufacturing process) fall naturally. Next, conversely, the exhaust side end is used as a fulcrum, the sealing side end is set up so that the inclination of the lamp is 80 degrees or more, and the other end (sealing side) is naturally dropped. After such overturning and dropping were repeated 5 times, the presence or absence of peeling of the phosphor was determined, and the number of samples with no peeling and the samples with peeling were counted.

  As shown in the column 25 of the number of occurrences of phosphor peeling in Table 1, the results of this sample test are as follows. In a conventional lamp that does not perform frosting, the phosphor layer peels off the glass tube 21 of any tube diameter, 23 also occurred. That is, four or two phosphors are peeled off in the samples 21a and 23a having no protective film, and 15 or 11 phosphors are peeled off in the samples 21ab and 23b coated with the protective film.

  On the other hand, in the lamp subjected to the frost processing of the present invention, no phosphor peeling occurred in all the samples 22a, 22b, 24a, and 24b regardless of the presence or absence of the protective film.

  Next, an illumination device using the above-described cold cathode fluorescent lamp will be described with reference to FIGS.

  FIG. 2 is a schematic view showing a configuration of a surface illumination device according to another embodiment of the present invention in which a plurality of cold cathode fluorescent lamps which have been subjected to the above-mentioned frost processing and formed a phosphor layer are arranged in parallel. The surface illumination device 40 shown in FIG. 4B is disposed on the back of a liquid crystal element of a liquid crystal display device, for example, and a backlight illumination unit in which the arranged cold cathode fluorescent lamps 41a to 41n illuminate the back surface of the liquid crystal element. It is used as

  FIG. 6A is a luminance distribution characteristic diagram showing the characteristic of luminance change in the cross-sectional direction along the arrangement direction. The luminance distribution characteristic 42 in the case where the conventional cold cathode fluorescent lamps without the frost processing shown in the figure are arranged has a small luminance and a high luminance, so that the luminance difference 42a between the luminance at the front of the lamp and the luminance at the center between the lamps is large. On the other hand, the luminance distribution characteristic 43 of the cold cathode fluorescent lamp according to the present embodiment subjected to the frost processing shown in the figure has a large luminance difference 43a compared with the luminance difference 42a of the conventional product, although the diffusion is large and the luminance is low. As a result, a surface illumination device with reduced luminance unevenness is realized. In a conventional surface illuminating device using a cold cathode fluorescent lamp that does not perform frost processing, it is necessary to arrange an optical member that reduces uneven brightness such as a diffusion plate in front of the cold cathode fluorescent lamp. In the backlight illumination device of the present invention using a cathode fluorescent lamp, these optical members are unnecessary, the cost can be reduced, and the illumination device can be made compact.

  FIG. 3 shows the luminance characteristics and the total luminous flux characteristics of the cold cathode fluorescent lamp subjected to the frost processing of the present embodiment and the conventional cold cathode fluorescent lamp not subjected to the frost processing. According to the luminance characteristic diagram shown in FIG. 6A, the characteristic 31 of the cold cathode fluorescent lamp subjected to the frost processing of the present embodiment has a luminance of about 7% as compared with the characteristic 32 of the conventional cold cathode fluorescent lamp. In the total luminous flux characteristic diagram shown in FIG. 4B, it can be seen that the cold cathode fluorescent lamp of this embodiment and the conventional product output the same luminous flux 33 in the range of the lamp current of 3 mA to 8 mA. . This difference in characteristics is considered to be due to the fact that the unevenness of the inner wall caused by the frost processing on the inner wall of the glass tube body by, for example, hydrofluoric acid in this embodiment diffuses the light generated by the lamp to a wide angle.

  The illumination device of the present invention is suitable for a backlight unit such as a liquid crystal display device because luminance unevenness in the arrangement direction of the cold cathode fluorescent lamps can be reduced and uniform illumination can be performed. Further, in this case, since an optical member for diffusion can be eliminated, there are advantages that the cost of the member can be reduced and the apparatus can be made compact.

The schematic cross section which shows the structure of the cold cathode fluorescent lamp of this invention. The figure which shows the structure and brightness nonuniformity characteristic of the surface lighting apparatus of this invention. The brightness | luminance characteristic view and total luminous flux characteristic view of the cold cathode fluorescent lamp of this invention and a conventional product. Sectional drawing which shows the structure of the conventional cold cathode fluorescent lamp.

Explanation of symbols

10, 51 ... glass tube,
11 ... Frosted inner wall surface,
12, 52 ... protective film,
13, 53 ... phosphor layer,
14, 56 ... electrodes,
15, 54 ... Air-sealing equipment,
16 ... Noble gas filling,
17, 55 ... incoming line,
20 ... Results table of phosphor peeling comparison test,
21, 23... Conventional product sample for phosphor peeling comparison test,
22, 24... This embodiment of the phosphor peeling comparison test (frost processing) sample,
21a, 22a, 23a, 24a ... Samples without a protective film in the phosphor peeling comparison test,
21b, 22b, 23b, 24b ... Samples with a protective film for phosphor peeling comparison test,
31 ... Luminance characteristics of this embodiment,
32 ... Luminance characteristics of conventional products,
33 ... The total luminous flux characteristics (characteristics overlap) of the conventional product and this embodiment,
40: Lighting device (BLU) of another embodiment,
41a, 41b-41n ... arranged cold cathode fluorescent lamps,
42: Distribution of light emission intensity of a lighting device in which conventional cold cathode fluorescent lamps are arranged,
42a ... the size of luminance unevenness of the illumination device in which the conventional cold cathode fluorescent lamps are arranged,
43 ... Distribution of light emission intensity of the illumination device of the present embodiment in which cold cathode fluorescent lamps by frosting are arranged,
43a ... The magnitude of luminance unevenness of the illumination device of this embodiment.

Claims (6)

A frosted layer formed on the inner wall of the glass tube,
A protective film layer formed on the surface of the frost layer;
A phosphor layer formed on the surface of the protective film layer;
A rare gas filled in the tube of the glass tube formed with the phosphor layer;
A cold cathode fluorescent lamp comprising a pair of electrodes sealed at both ends of the glass tube filled with a rare gas. A frosted layer formed on the inner wall of the glass tube,
A phosphor layer formed on the surface of the frost layer;
A rare gas filled in the tube of the glass tube formed with the phosphor layer;
A cold cathode fluorescent lamp comprising a pair of electrodes sealed at both ends of the glass tube filled with a rare gas.   The cold cathode fluorescent lamp according to claim 1 or 2, wherein the frosted layer is formed by a hydrofluoric acid treatment. Forming a frosted layer on the inner wall of the glass tube;
Forming a protective film layer on the surface of the frosted layer;
Forming a phosphor layer on the surface of the protective film layer;
Filling the rare earth gas into the tube of the glass tube with the phosphor layer formed;
A method of manufacturing a cold cathode fluorescent lamp, comprising a step of sealing a pair of electrodes on both ends of the glass tube filled with a rare gas. Forming a frosted layer on the inner wall of the glass tube;
Forming a phosphor layer on the surface of the frosted layer;
Filling the rare earth gas into the tube of the glass tube with the phosphor layer formed;
A method of manufacturing a cold cathode fluorescent lamp, comprising a step of sealing a pair of electrodes on both ends of the glass tube filled with a rare gas.   4. An illuminating device comprising a plurality of the cold cathode fluorescent lamps according to claim 1 arranged in an array.