JPH0212292A - Lighting device - Google Patents

Abstract

PURPOSE:To prevent an illumination intensity distribution from becoming irregu lar in its early stage by housing a cold cathode fluorescent lamp in a lamp storage space at such an attitude that the plate type surface of the cold cathode does not a light guide-out, i.e. an irradiated surface side. CONSTITUTION:Part of light emitted by fluorescent lamps 5 and 5 is reflected by the reflecting surface 4 of the bottom surface of a casing 1 to travel to the light diffusing and transmitting plate 11 of an opening part while the remaining light travels to the light diffusing and transmitting plate 11 directly. The fluorescent lamps 5 and 5 are fitted to the casing 1 so that the roof-shaped wide plate surfaces 7a of the cold cathodes 7 and 7 do not face the opening part of the casing 1, namely, that the V-shaped flanks 7b face the opening part of the casing 1. Consequently, the bulb surfaces which are blackened quickly are prevented from facing the irradiated surface and the irregularity in the illumination intensity distribution is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an illumination device using a cold cathode fluorescent lamp as a light source.

(Conventional technology) LCD televisions, LCD meters, etc. display light on the LCD screen by shining light from the back of the LCD panel. Such backlights illuminate the entire LCD screen with a predetermined spread. Because it is necessary to irradiate with uniform brightness, a hot cathode or cold cathode fluorescent lamp is used as the light source.

Since such a fluorescent lamp has a long discharge path, it has a large light emitting area and has the advantage of easily achieving uniform light distribution.

However, in recent years, as this type of OA equipment has become smaller and thinner, the space for accommodating the lamp has also become smaller and thinner, and hot cathode fluorescent lamps, which generate more heat, have become disadvantageous.

Therefore, there is an increasing trend to use cold cathode fluorescent lamps as light sources.

(Problem to be Solved by the Invention) However, in order to capture electrons over a wide area, cold cathode fluorescent lamps use plate-like members as their electrode structure, and are given a shape such as a roof shape. .

When such a plate-shaped cold cathode is used for a long time, the electrode material scatters and adheres to the bulb, causing the bulb to turn black. In this case, a large amount of light is scattered from the large surface of the plate-shaped cold cathode, so the bulb wall surface facing this surface becomes blacker than other parts, blocking light. That is, in the bulb, the degree of blackening progresses differently between the portion facing the large plate surface of the plate-shaped cold cathode and the other portions, resulting in variations in the degree of blackening progress in the circumferential direction of the bulb.

If such a surface where blackening progresses quickly is placed facing the liquid crystal, etc., the brightness of the portion facing the blackened portion of the liquid crystal panel surface will be reduced, leading to a decrease in the performance of the liquid crystal panel.

In particular, in the case of a liquid crystal television, there is a problem that the blackened portion deteriorates the quality of the pixels.

The present invention aims to provide an illumination device that can reduce uneven illuminance distribution in the light extraction direction, that is, on the irradiated surface due to bulb blackening.

[Structure of the invention]

(Means for Solving the Problems) The present invention accommodates a cold cathode fluorescent lamp having a cold cathode made of a plate material in a lamp housing space, and directs light emitted from the lamp from one side of the lamp housing space. In the lighting device, the cold cathode fluorescent lamp is housed in the lamp housing space in such a manner that the plate-like surface of the cold cathode does not face the light extraction side of the lamp housing space. shall be.

(Function) According to the present invention, the cold cathode fluorescent lamp is housed in the lamp housing space in such a position that the plate-like surface of the cold cathode does not face the light extraction side, that is, the irradiated surface side. This prevents the bulb surface, which is rapidly changing, from facing the irradiated surface, thereby reducing uneven illuminance distribution.

(Example) The present invention will be described below based on an example shown in the drawings.

In the figure, 1 is a casing, which is made of synthetic resin such as polycarbonate. This casing l has a partition part 2 integrally formed in the central part thereof to protrude along the longitudinal direction, and for this reason, the casing 1 is provided with two hammer-shaped recesses 3 and 3 each having a quadratic curve in cross section. It is formed into a shape.

The entire bottom surface of the casing 1 is a reflective surface 4 made of a white or aluminum vapor-deposited film.

The casing 1 includes a straight tube type cold cathode fluorescent lamp 5.
5 is accommodated.

The cold cathode fluorescent lamp 5, as shown in FIG. A phosphor wave film 9 is formed on the inner surface of 6. The bulb 6 is filled with a predetermined amount of mercury and a starting rare gas such as argon or xenon.

The cold cathodes 7, 7 of the lamp 5 are formed by bending a plate made of, for example, brass into a roof shape (chevron shape), and connect the lead wires io, to with the top of the roof shape facing the discharge side.
is supported by

Such cold cathode fluorescent lamps 5.5 are each housed in a hammer-shaped recess 3.3 of the casing 1.

In this case, the cold cathode 7.7 of the lamp 5 is arranged so that the roof-shaped wide plate surface 7a does not face the opening of the casing 1, that is, the V-shaped side surface 7b faces the opening of the casing 1. It is fixed to the casing 1 in this manner.

A light diffusing and transmitting plate 11 is attached to the upper opening of the casing 1 . The light diffusing and transmitting plate 11 is made of milky white material such as acrylic resin and has a light diffusing and transmitting effect.

The operation of the embodiment with such a configuration will be explained.

When the fluorescent lamps 5.5 are energized, these lamps 5.5
is discharged between the cold cathode electrodes 7 and emits light.

A part of the light emitted from the fluorescent lamp 5.5 is reflected by the reflective surface 4 on the bottom of the casing l and directed to the light diffusing and transmitting plate 11 in the opening, and the remaining light is directly reflected by the light diffusing and transmitting plate 1.
Head to 1. Therefore, almost all of the light emitted from the lamp 5.5 is irradiated to the outside through the light diffusing and transmitting plate 11,
The back surface of a liquid crystal panel (not shown) provided on the entire surface is irradiated.

In this case, since the reflective surface 4 of the casing 1 is a quadratic curved surface, the light reflected by the reflective surface 4 is transmitted to the casing 1.
With respect to the aperture, the light is refracted and reflected so that the brightness of the entire surface of the aperture becomes approximately uniform.

For this reason, the luminance distribution on the light diffusing and transmitting plate 11 becomes uniform over the entire surface, reducing unevenness in luminance.

By the way, the fluorescent lamp 5.5 is designed so that the roof-shaped wide plate surface 7a of the cold cathode 7.7 does not face the opening of the casing l, that is, the V-shaped side surface 7b faces the casing l. Casing 1 facing the opening
Since the bulb B is attached to the bulb B, uneven brightness caused by the blackening of the bulb B can be eliminated.

That is, as shown in FIGS. 2 to 4, in the cold cathode 7, the projected area A of the roof-shaped wide plate surface 7a on the bulb surface is larger than the projected area B of the V-shaped side surface 7b on the bulb surface. big. Therefore, the scattering of electrode material is prevented from occurring on the plate surface 7.
a becomes larger than the side surface 7b side, and therefore, on the wall of the bulb 6 facing these surfaces, the plate surface 7a side, where there are many scattered substances, adheres more than the side surface 7b side, where there are fewer scattered substances, and blackening progresses earlier.

As blackening progresses, light is blocked and brightness decreases.

However, in this embodiment, the V-shaped side surface 7 of the cold cathode 7
Since b was installed facing the opening of casing l,
The wall of the bulb 6 has a surface on which less scattered substances are attached, which faces the light diffusing and transmitting plate 11 side. Therefore, the brightness distribution on the light diffusing and transmitting plate 11 is prevented from becoming uneven for a long period of time.

In the case of the above embodiment, the casing 1 was made of synthetic resin such as polycarbonate, but the present invention is not limited to this, and the casing 1 may be made of metal.
The space for accommodating the lamp is not necessarily a special casing as described above, but may be a lamp accommodating space within the OA equipment.

Further, the fluorescent lamp is not limited to a straight tube shape, but may be a curved tube shape such as a U-shape or a W-shape.

Furthermore, the fluorescent lamp may be one in which only a rare gas is sealed in the bulb without mercury.

〔Effect of the invention〕

As explained above, according to the present invention, the cold cathode fluorescent lamp is housed in the lamp housing space in such a position that the plate-like surface of the cold cathode does not face the light extraction side, that is, the irradiated surface side. The bulb surface, which undergoes rapid deterioration, does not face the irradiated surface, so that it is possible to prevent the illuminance distribution on the irradiated surface from becoming uneven at an early stage.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is an exploded perspective view of the entire lighting device, FIG. 2 is a perspective view showing the structure of a cold cathode fluorescent lamp, and FIGS. 3 and 4 are different from each other. FIG. 3 is a cross-sectional view of the end of the fluorescent lamp showing the cold cathode portion as seen from the direction; DESCRIPTION OF SYMBOLS 1... Casing, 4... Reflective surface, 5... Cold cathode fluorescent lamp, 6... Bulb, 7... Cold cathode, 7a
. . . Plate surface portion, 7b . . . Side portion, 9 . . . Phosphor coating, 11 . Applicant's representative Patent attorney Takehiko Suzue A Figure 91 Outside/Nine body fluids diagram

Claims (1)

[Claims] A lighting device in which a cold cathode fluorescent lamp having a cold cathode made of a plate material is housed in a lamp housing space, and light emitted from the lamp is extracted from one side of the lamp housing space, wherein the cold cathode fluorescent lamp A lighting device characterized in that a lamp is housed in a lamp housing space in such a manner that the plate-like surface of the cold cathode does not face the light extraction side of the lamp housing space.