JPH0552024B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a flat fluorescent lamp suitable for backlighting of liquid crystal display devices such as liquid crystal TVs. (b) Prior Art In recent years, so-called liquid crystal TVs using liquid crystal display devices have been developed in order to make TV receivers thinner. Since the liquid crystal panel used in this liquid crystal TV does not emit light by itself, it is necessary to use some kind of light source as a backlight to transmit light through the liquid crystal to obtain a certain level of brightness. Normally, the following conditions are required for the above-mentioned backlight. It must be a flat light source that matches the size of the LCD TV (3:4 aspect ratio). The brightness on the light source surface must be uniform. Good luminous efficiency. Low temperature rise. Good color rendering. Among these conditions, especially small size and
This is an essential condition for realizing high-definition LCD TVs. Conventionally, it has been considered to arrange a plurality of cylindrical fluorescent lamps on the back surface of the liquid crystal panel as the backlight, but this is not very preferable because it causes uneven brightness of the plurality of fluorescent lamps on the screen. It is also conceivable to use a flat type fluorescent lamp such as that disclosed in Japanese Patent Application Laid-open No. 54-90877, and with this flat type fluorescent lamp, uneven brightness can be improved to some extent compared to the above-mentioned method. On the other hand, according to the applicant's experiments, the relationship between gas pressure and brightness is as shown in Table 1.

[Table] Argon gas is used here, and the brightness is
It is relative to the brightness of 100 at 1Torr. As is clear from this table, as the gas pressure is increased, the brightness increases in proportion. Furthermore, it has been confirmed that even if the gas pressure increases, the power required for discharge remains almost the same. Therefore, even when the above-mentioned flat fluorescent lamp is used as a backlight, it is advantageous to increase the gas pressure as much as possible because high brightness can be obtained. However, according to the applicant's experiments, when using the above-mentioned flat fluorescent lamp, when the gas pressure is 3 Torr or less, discharge occurs almost uniformly over the entire fluorescent surface, but when it exceeds 3 Torr, the discharge occurs. It was confirmed that the occurrence was concentrated in the center of the fluorescent surface. Therefore, when trying to obtain high brightness, brightness unevenness occurs on the screen, causing a problem. Furthermore, since the above-mentioned planar fluorescent light is a hot cathode type using a filament, it consumes a large amount of power and generates a large amount of heat. Furthermore, the above-mentioned flat fluorescent lamps are not specifically intended for use in LCD TVs, so they do not match the TV screen size (3:4 aspect ratio), and although they are flat, they are relatively small. It has an elongated shape. In view of the above points, the flat fluorescent lamp described in the above-mentioned publication does not satisfy the conditions desired for a backlight of a liquid crystal TV and is not suitable for a liquid crystal TV. (C) Object of the Invention The present invention proposes a flat fluorescent lamp that eliminates the drawbacks of conventional flat fluorescent lamps and satisfies the conditions desired for the backlight of a liquid crystal TV. (d) Structure of the Invention The present invention provides a flat fluorescent lamp sealed by a pair of flat top glasses, in which a pair of electrodes are arranged approximately parallel to a line connecting the pair of electrodes and at approximately equal intervals. This is a flat fluorescent lamp with a protrusion having a triangular cross section. (e) Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a flat fluorescent lamp according to this embodiment, and FIGS. 2A, 2B, and 2 are a plan view, a longitudinal cross-sectional view, and a cross-sectional view, respectively, of the flat fluorescent lamp. In the figure, numerals 1 and 2 are upper and lower sealing glasses made of transparent glass, respectively, and are formed into a rectangular shape with an aspect ratio of 3:4. The upper sealing glass 1 has an upper plate and a side plate integrally molded, and an exhaust pipe 1a is formed on one side. On the other hand, the lower sealing glass 2 has a flat plate shape, and includes recesses 2a, 2a in which a pair of electrodes, which will be described later, are located, and a terminal guide groove 2.
b, 2b, 2b, 2b, and a plurality of protrusions 2c, 2c... parallel to the discharge path and having a triangular cross section are integrally molded at approximately equal intervals. Fluorescent lamps are applied to the inner walls of both sealing glasses, respectively. Reference numerals 3 and 3 designate a pair of electrodes made of stainless steel or iron-nickel alloy and having a U-shaped cross section, and are respectively disposed within the recesses, and from the sides thereof, respectively.
A pair of terminals 3a, 3a... protrudes toward the outside. The electrode type in this embodiment is a cold cathode type in which the cathode is a cold cathode. Reference numeral 4 denotes a sealing material such as a glass frit for tightly sealing the upper and lower sealing glasses, whereby argon gas and mercury are sealed inside both the sealing glasses 1 and 2. Next, a method for manufacturing the above-mentioned flat fluorescent lamp will be explained. First, the recesses 2a, 2a, the terminal guide grooves 2b, 2b
A pair of electrodes 3, 3 is placed on the lower sealing glass 2 on which the projections 2c, 2c, . . . are integrally molded. Next, the lower sealing glass 2 and the upper sealing glass 1 are thermally welded together using the sealing material 4, thereby completing the flat fluorescent lamp 10. In this state, the upper and lower sealing glasses are completely adhered to each other. Further, in this state, the tip of the protrusion is in contact with the inner wall of the upper sealing glass, so that the structure is such that the implosion of the glass due to atmospheric pressure is mechanically prevented. Finally, air is exhausted from the exhaust pipe 1a, and argon gas and mercury are allowed to flow in, and the exhaust port of the exhaust pipe is sealed by thermal welding or the like. When a predetermined voltage is applied to the electrodes of the flat fluorescent lamp prepared as described above, discharge starts, but the discharge is uniformly carried out following the discharge paths formed in parallel by the respective protrusions 2c, 2c... This results in substantially uniform brightness over the entire fluorescent surface. Further, since the protrusion has a triangular cross-section, the luminance at the flat part of the lower sealing glass and the inclined part of the protrusion becomes equal in the direction perpendicular to the flat part due to the reflection effect (diffuse reflection) of the inclined part, and
Since the contact area of the contact portion between the apex of the protrusion and the upper sealing glass can be ignored, no darkening occurs in this portion. Furthermore, since the electrodes 3 and 3 are each formed in a U-shape, their surface area is larger than that of a flat plate electrode, so the amount of electrons emitted per one discharge path increases, and the generation efficiency increases. good. Next, we will introduce an LCD TV using the above-mentioned flat fluorescent lamp.
An example will be explained. 3A and 3B are a cross-sectional view and a vertical cross-sectional view of a liquid crystal TV, in which a liquid crystal panel 20 is integrally molded on the upper sealing glass 1 of a flat fluorescent lamp 10. This liquid crystal panel and the flat fluorescent lamp have the same planar shape (an aspect ratio of 3:4). The liquid crystal panel 20 has the upper sealing glass 1 as a substrate, a spacer 21 and a glass plate 22.
A color filter 24, a pair of matrix electrodes 25 and 26, and a liquid crystal 27 are sealed in a sealed chamber formed by a sealing material 23 that seals these, and is formed according to a well-known liquid crystal panel manufacturing method. Ru. According to the above-mentioned LCD TV, since the upper sealing glass of the flat fluorescent lamp is used as the substrate glass of the liquid crystal panel, an extremely thin TV can be formed, and the liquid crystal panel and the flat fluorescent lamp are extremely close to each other. Because of this, the luminous efficiency is extremely high, and uniform, high-brightness image quality can be obtained. In the above-described embodiment, the upper sealing glass of the flat fluorescent lamp was used as the substrate glass of the liquid crystal panel, but it may be integrated with a conventional liquid crystal panel by adhesion or the like on the upper sealing glass. (f) Effects of the invention As mentioned above, the flat fluorescent lamp of the present invention has a plurality of protrusions parallel to the discharge path.
Even if the gas pressure is increased, uniform brightness can be obtained on the light emitting surface. By bringing the tips of the protrusions into contact with or close to the opposing sealing glass, implosion due to atmospheric pressure can be prevented. Because it uses a cold cathode type, it does not generate heat, and even if the liquid crystal panels are placed close together, the temperature of the liquid crystal will not rise. The electrodes are U-shaped to increase the surface area, resulting in good luminous efficiency. It has the following advantages and can satisfy the conditions desired for backlights of liquid crystal TVs and the like.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of the flat fluorescent lamp in this embodiment, Fig. 2 A, B, and C are the same plan view, cross-sectional view, and longitudinal sectional view, respectively, and Fig. 3 A, B are the above. 1 is a cross-sectional view and a longitudinal cross-sectional view of a liquid crystal TV to which a flat fluorescent lamp is applied. Explanation of main drawing numbers, 1, 2...Top and bottom sealed glass,
3, 3...Pair of electrodes, 2c, 2c...Protrusion, 2
0...LCD panel.

Claims (1)

[Claims] 1. In a flat fluorescent lamp whose interior is sealed by a pair of flat glasses, a pair of plate electrodes are formed on both sides of the inside, and the bottom surface is in contact with one of the flat glasses. , a planar type characterized in that protrusions having a triangular cross section whose tips abut or are close to the other flat glass are arranged approximately parallel to the line connecting the pair of plate electrodes and at approximately equal intervals. Fluorescent light. 2. The flat fluorescent lamp according to claim 1, wherein the pair of plate-shaped electrodes have a U-shaped cross section.