KR100687339B1 - Fluorescent lamp of back light unit for LCD - Google Patents

Abstract

The present invention discloses a fluorescent lamp of a backlight unit for a liquid crystal display device capable of preventing luminance unevenness in each region. The fluorescent lamp of the present invention, which is a means for generating light, has a structure in which a phosphor is coated on an inner surface of a glass tube, electrodes are fitted at both ends of the glass tube, and a discharge gas is filled in the glass tube. In the fluorescent lamp of the backlight unit, the fluorescent material is coated so as to become thinner toward the center from both edges of the glass tube adjacent to the both ends of the electrode so as to prevent the decrease in brightness at both ends of the electrode.

Backlight Unit, Fluorescent Lamp, Phosphor

Description

Fluorescent lamp of backlight unit for liquid crystal display device {Fluorescent lamp of back light unit for LCD}

1 is a cross-sectional view showing a fluorescent lamp of a conventional backlight unit.

2 is a view for explaining a conventional problem.

3 is a cross-sectional view showing a fluorescent lamp of the backlight unit according to the present invention.

4 is a view for explaining a liquid crystal display device to which a fluorescent lamp according to the present invention is applied.

5 is a view showing the screen quality of the backlight unit to which the fluorescent lamp is applied according to the present invention.

Explanation of symbols on the main parts of the drawings

32: glass tube 34: phosphor

36 electrode 40 fluorescent lamp

42: liquid crystal panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit for a liquid crystal display device, and more particularly, to a fluorescent lamp of a backlight unit for preventing a luminance deterioration phenomenon from occurring in an electrode portion.

Liquid crystal displays (LCDs), unlike plasma display panels (PDPs) and light emitting displays (LEDs), are non-light-emitting devices and therefore cannot be used in the absence of light. Therefore, the liquid crystal display device requires a separate light source to be able to use in a dark place.

As a separate light source, a liquid crystal display device is equipped with a backlight unit. The backlight unit uses a Cold Cathode Fluorescent Lamp (CCFL) or an External Electrode Fluorescent Lamp (EEFL) as a practical light source, and transmits the light generated by the fluorescent lamp through the light guide plate. Projected onto the display surface of the liquid crystal panel.

In addition, in order to project more light generated from the fluorescent lamp to the light guide plate, a lamp reflector is installed around the fluorescent lamp, and a reflector sheet is installed at the lower end of the light guide plate to emit light. An optical sheet is formed by reflecting the panel display surface, and a diffuser sheet, a prism sheet, and a protector sheet are sequentially provided on the upper surface of the light guide plate.

Meanwhile, the edge light type backlight unit is assembled by stacking the optical sheets on a mold frame in a top down manner, and at the bottom thereof, a metal back cover is disposed. The outer part is wrapped in a press called bezel.

However, the fluorescent lamp of the backlight unit, as shown in Figure 1, the phosphor 4 is coated on the inner surface of the glass tube 2, the electrode 6 is fitted to both ends of the glass tube (2) In this case, the glass tube 2 is filled with a discharge gas such as Ne or Ar, and the luminance decrease occurs at the electrode 6 in relation to the uniform coating thickness of the phosphor 4. As shown in FIG. 2, the amount of light transmitted from the fluorescent lamp 10 to the light guide plate (not shown) of the backlight unit differs from one region to another, resulting in a liquid crystal panel 12 corresponding to the fluorescent lamp 10. The luminance decreases at both ends.

Accordingly, an object of the present invention is to provide a fluorescent lamp of a backlight unit for a liquid crystal display device, which can be prevented from occurring in a lowering of brightness in an electrode part.

In addition, another object of the present invention is to provide a fluorescent lamp of a backlight unit for a liquid crystal display device which can prevent the occurrence of luminance non-uniformity caused by the fluorescent lamp so that excellent screen quality can be realized.

In order to achieve the above object, the present invention is a means for generating light, the phosphor is coated on the inner surface of the glass tube, the electrode is fitted to both ends of the glass tube, the discharge gas is filled in the glass tube In a fluorescent lamp of a backlight unit for a liquid crystal display device, the phosphor is a glass tube adjacent to the both ends of the electrode by controlling any one of the number of times of coating and the adjustment of the coating liquid viscosity to prevent a decrease in brightness at both ends of the electrode portion. Provided is a fluorescent lamp of a backlight unit for a liquid crystal display device, characterized in that the coating is thinned toward the center from both edges.

Here, the coating thickness of the phosphor is coated at least two times on both edges of the glass tube, or by increasing the viscosity of the coating solution so that the coating thickness of both edges of the glass tube is relatively thicker than the center portion.

For example, the phosphor adjusts the coating thickness at both edges of the glass tube to about 10 to 30 μm and the coating thickness at the center of the glass tube to about 5 to 20 μm.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In general, electrons generated at the electrode part during the discharge of the fluorescent lamp excite ultraviolet rays inside the glass tube to generate secondary electrons, and the generated secondary electrons excite the phosphor to generate visible light which becomes visible. At this time, the intensity of visible light increases as the thickness of the phosphor coating increases, and the luminance also increases.

The light emitted from the fluorescent lamp with increased brightness is transmitted to the light guide plate together with the light reflected from the lamp reflector, and the light propagated upward by the light transmitted to the light guide plate and the reflective sheet under the light guide plate and the diffusion sheet and prism sheet. The display panel of the liquid crystal panel seen by the user passes through the same optical sheet.

Here, the screen quality of the liquid crystal display device may be determined by the fluorescent lamp. For example, when the light is uniformly emitted from the entire area of the fluorescent lamp, it is possible to implement the liquid crystal display device of excellent screen quality.

However, the fluorescent lamp of the conventional backlight unit does not emit light uniformly in all areas. This is because the amount of secondary electrons generated at the electrode portion during discharge of the fluorescent lamp is smaller than that at the lamp center portion, so that visible light of relatively smaller intensity is generated at the electrode portion than the lamp center portion.

Therefore, the present invention allows the visible light to be generated with uniform intensity in all regions of the fluorescent lamp by varying the thickness of the phosphor coating for each region.

That is, as shown in Figure 3, the present invention is the phosphor 36 is coated on the inner surface of the glass tube 32, the electrode 34 is fitted to both ends of the glass tube 332, the glass tube 32 In implementing the fluorescent lamp 40 having a structure filled with a discharge gas (not shown) in the), the thickness of the phosphor 36 toward the center from both edges of the glass tube 32 adjacent to the electrode 34 on both sides To make it thinner. For example, the coating thickness of the phosphor 36 at the edge of the glass tube 32 is adjusted to about 10 to 30 μm, and the coating thickness of the phosphor 36 at the center of the glass tube 32 is adjusted to about 5 to 20 μm.

Here, the coating of the phosphor 36 is carried out by applying a method of coating from the bottom up, a method of coating from the top to the bottom, and a method of coating sideways. Preferably, the glass tube is placed in a bath containing the phosphor coating solution. This is done in a dipping manner.

In addition, the coating thickness of the phosphor 36 may be controlled by controlling the number of coatings or adjusting the viscosity of the coating liquid. For example, at least two coatings may be performed on both edges of the glass tube 32, or by increasing the viscosity of the coating liquid. The coating thickness at the edges is made relatively thicker than the center portion.

According to the fluorescent lamp of the present invention as described above, the phosphor coating thickness at the electrode portion is made relatively thicker than other portions to excite more electrons in the phosphor coated with the relatively thick ultraviolet light generated at the electrode portion. As a result, the visible light intensity at the electrode portion is increased so that the visible light is uniformly generated in the entire area of the fluorescent lamp and uniformly transmitted to the entire light guide plate (not shown) of the backlight unit. As shown in FIG. 2, luminance uniformity in the liquid crystal panel 42 can be improved.

5 is a view illustrating a screen quality of a backlight unit to which a fluorescent lamp having a different phosphor coating thickness is applied according to the present invention. As illustrated, an excellent screen quality may be obtained through uniformity of luminance from a fluorescent lamp.

As described above, the present invention can remove the relative darkness at both ends of the lamp by varying the coating thickness of the phosphor for each lamp area, thereby increasing the luminance uniformity of the fluorescent lamp and the luminance uniformity of the backlight unit. As a result, it is possible to improve the luminance uniformity of the liquid crystal display device and to provide a liquid crystal display device having a good screen quality.                     

As mentioned above, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (5)

delete In the fluorescent lamp of the backlight unit for a liquid crystal display device having a structure for generating light, the phosphor is coated on the inner surface of the glass tube, the electrode is fitted to both ends of the glass tube, the discharge gas is filled in the glass tube, The phosphor is coated to become thinner from the edges of both sides of the glass tube adjacent to the both electrodes toward the center by controlling any one of the number of coatings and the adjustment of the coating liquid viscosity so as to prevent the decrease in luminance at both electrode portions. A fluorescent lamp of a backlight unit for a liquid crystal display device, characterized in that. The fluorescent lamp of claim 2, wherein the phosphor is coated at least twice on both edges of the glass tube. 3. The fluorescent lamp of claim 2, wherein the phosphor has a high viscosity of the coating solution so that the coating thickness of both edges of the glass tube is relatively thicker than that of the center part. The backlight unit of claim 2, wherein the phosphor adjusts the coating thickness at both edges of the glass tube to 10 to 30 μm and the coating thickness at the center of the glass tube to 5 to 20 μm. Fluorescent lamps.

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