FLAT TYPE FLUORESCENT LAMP
FIELD OF THE INVENTION The present invention relates to a flat type fluorescent lamp, and more particularly, to a flat type fluorescent lamp that can partly perform the discharge in a discharge space using opposing discharge electrodes, thereby improving a discharge efficiency by converting a non-emission region formed by a zigzag discharge path and spacers into a light emission region while saving the electric power.
BACKGROUND OF THE INVENTION A flat type fluorescent lamp has been widely used as a backlight of a flat display device or lighting device, being increasingly applied to a variety of applications. FIG. 1 shows a conventional flat type fluorescent lamp. As shown in the drawing, a conventional flat type fluorescent lamp includes two flat glass substrates 1, a sidewall 3 coupling the glass substrates to each other, and a plurality of spacers 5 disposed between the glass substrates 1 to uniformly maintain a gap between them and define a discharge path. A phosphor layer (not shown) is deposited on an inner surface of a lamp body and discharge electrodes are formed on both ends of the sidewalls. Inner air is exhausted through an exhaust tube 9 formed on the sidewall 3, after which the exhaust tube 9 is sealed. The spacers 5 are designed to be less than a width of the lamp body. That is, the spacers and the sidewall define a plurality of alternate gaps, thereby defining a zigzag-shaped discharge path. When voltage is applied to the discharge electrodes 7 formed on the both ends of the fluorescent lamp, discharge is realized on the discharge path, thereby exciting the phosphor layer to function as a planar light source.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plane sectional view of a conventional flat type fluorescent lamp; FIG. 2 is an exploded perspective view of a flat type fluorescent lamp according to an embodiment of the present invention; FIGS. 3 through 5 are perspective views illustrating a variety of modified examples of spacers of the present invention; FIGS. 6 through 10 are perspective views of a variety of opposing discharge electrodes of the present invention.
TECHNICAL PROBLEMS Although the above-described conventional flat type fluorescent lamp can realize the planar light source, it has a disadvantage of not providing a uniform brightness and light emission. For example, in the conventional flat type fluorescent lamp, a long discharge path is defined in a zigzag shape in the lamp body, thereby making it difficult to improve the light emission efficiency and provide the uniform brightness. To solve this problem, power of the discharge electrodes oppositely disposed should be increased. In this case, the power consumption is increased. In addition, since the plate type spacers are designed having a predetermined width, a non-emission region is created as large as the width of the spacers. Therefore, the width of the spacers should be reduced as large as possible. However, there is limitation in reducing the width of the spacers. To solve the problems, a diffusing plate is installed on a front light emission surface of the plat type fluorescent lamp. However, since the disusing plate simply functions to compensate the uniformity of the light emission while suppressing the light emission at a high brightness region, thereby deteriorating the overall brightness efficiency.
SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above-described problems. It is an objective of the present invention to provide a flat type fluorescent lamp that induce a straight part discharge in a discharge space using opposing discharge electrodes, as a result of which a non-emission region caused by a zigzag discharge path and spacers can be changed into the light emission region, thereby improving the light emission efficiency and the uniformity of the brightness while saving the electric power. To achieve the above objective, the present invention provides a flat type fluorescent lamp comprising: a lamp body defining an inner discharge space; a phosphor layer applied on an inner surface of the lamp body; and opposing electrodes installed on opposite sides of the lamp body, respectively. The flat type fluorescent lamp may further comprise spacers installed in the lamp body to define the inner discharge space and a discharge path. Preferably, the spacer is formed of a tube-type with a circular, an oval or a polygonal shape in a section, or formed of a bar-type with a plate shape or a mountain shape. The spacer may be provided with a plurality of apertures or a longitudinal slot. The opposing discharge electrodes may be formed having an uneven surface, thereby increasing the surface area thereof. The opposing discharge electrodes may be selected from the group consisting of a hollow cathode, a micro hollow cathode, a nanotube, a carbon nanotube, a metal wire, and a metal hollow wire. The opposing discharge electrodes may be coated on an inner surface of the lamp body. Preferably, the opposing discharge electrodes are formed of a material selected from the group consisting of diamond like carbon, amorphous carbon and boron nitrite.
INDUSTRIAL APPLICABILITY According to the inventive flat type fluorescent lamp, the non-emission region of the prior art can be changed into the light emission region by partly forming a straight discharge path using tube or bar-shaped spacers and installing opposing discharge electrodes at both sides of the straight discharge path. In addition, a short straight discharge path can be realized, as a result of which the light emission efficiency and the uniformity of the brightness can be enhanced, and the power consumption can be reduced. Therefore, a planar light source having the improved light emission efficiency can be realized.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in more detail hereinafter in conjunction with the accompanying drawings. FIG. 2 shows a flat type fluorescent lamp according to an embodiment of the present invention. As shown in the drawings, the inventive flat type fluorescent lamp is for realizing a planar light source such as a backlight of a flat display device or lighting device, having a rectangular parallelepiped lamp body. The lamp body includes transparent front and rear panels 11 and 13 and a side seal members 15, 17 and 19 attaching the front and rear panels 11 and 13 to each other. The rear plate 13 and the side seal members 15, 17 and 19 may be formed of transparent or semitransparent material. In addition, a reflective layer may be further provided on the rear plate 13. The side seal members 19 defining the lamp body may be formed in a structure identical to spacers while the side seal members 15 and 17 are formed of a flat plate. A length of the side seal member 19 is identical to a longitudinal length of the lamp body. As a feature of the present invention, spacers 21 are disposed between the front and rear panels 11 and 13. The spacers 21 are formed of tube-type with a circular, an oval or a polygonal shape in a section or formed of a bar-type, such as a plate type or mountain shape. To open opposite ends of the spacer 21 , the spacer 21 is designed to be shorter than the seal member 19. FIGS. 3 through 5 show a variety of examples of the spacers 21. Referring first to FIG. 3, the spacer 21 may be designed having a section formed in a circular shape and provided with a plurality of apertures 21a. Referring to FIG. 4, the spacer 21 may be designed having a circular shape and provided with a longitudinal slot 21a. Referring to FIG. 5, the spacer 21 may be formed of a bar-type having section formed in a mountain-shape and provided with a plurality of apertures 21a. According to a feature of the present invention, a non-emission region caused by the spacers 21 is to be minimized and a prior zig-zag discharge path is partly formed in a straight line. Particularly, when the spacer is formed in a tube or bat type, a phosphor layer is applied on inner and outer surfaces, thereby removing the non-emission region. As a result, the non-emission region in the prior art is changed into the light emission region, thereby realizing the uniform light emission and improving the light emission efficiency. Here, the phosphor layer is applied after the front and rear panels 11 and 13 and the side seal members 15, 17 and 19 are integrally assembled. After the phosphor layer is applied, the side seal members 15 and 17 are bonded by adhesive and molten bonding processes, thereby realizing the lamp body. According to another feature of the present invention, opposing discharge electrodes 23 are installed on opposite sides of the straight discharge path defined by the spacers 21 and supported by the side seal members 15 and 17, respectively. The opposing discharge electrodes 23 may be provided in a plurality of pairs. By the above-described structure, the discharge path enables the short straight discharge to be partly realized. That is, the inner and outer portions of the spacers 21 become the discharge path, thereby providing the uniform brightness, improving the light emission efficiency and allowing the low voltage operation. Particularly, as shown in FIG. 6, the opposing discharge electrodes 23 may be formed having an uneven surface 23a through a sanding, etching, injection or other physical processes, thereby increasing the surface area thereof. In addition, as shown in FIG. 7, the opposing electrodes 23 may be formed of a hollow cathode 23b, a micro hollow cathode, a nanotube, or a carbon nanotube, having an uneven surface 23c. FIG. 8 shows a concave portion 23c formed on the opposing discharge electrodes 23. As shown in FIG. 9, the opposing electrodes 23 may not be separately prepared but formed by directly coating electrode materials on the side seal members 15 and 17. As shown in FIG. 10, the opposing electrodes 23 may be formed of a metal wire or a metal hollow wire. At this point, the spacer 21 is provided at opposite ends with grooves through which the opposing discharge electrodes 23 can pass. The opposing discharge electrodes 23 may be formed of a material selected from the group consisting of Ni, Nb, W, and Mo. Preferably, the opposing discharge electrodes 23 may be formed of a material selected from the group consisting of diamond like carbon, amorphous carbon, and boron nitrite. In order to make the inner discharge space of the above-described flat type fluorescent lamp vacuum, an exhaust tube 25 is installed and supported on the side seal member 15. After the inner discharge space is vacuumed, the exhaust tube 25 is sealed through a molten process. Then, inner impurities are removed through a gettering process. According to the present invention, a diffusing plate may be further provided on the front surface of the fluorescent lamp.
