JPH06260149A - Flat form fluorescent lamp - Google Patents

Abstract

PURPOSE:To enhance the directivity of the emitted light and improve the light emitting efficiency of a fluorescent substance by embodying the outside and inside of a front glass panel in the form of a prism. CONSTITUTION:The outside 3b and inside 3a of a front glass panel 3 are processed into the form of a prism, and a fluorescent substance 6 and anode 7 are laminated on the inside surface 3a. Of those beams of light incident to the surface 3b from the surface 3a, the beams incident to the surface 3b at an angle within a certain critical value penetrate the surface 3b to be emitted in the normal direction or near it relative to the front surface of the panel 3. When the angle of ioncidence to the surface 3b exceeds the critical value, the light is total reflected by the surface 3b in the panel 3, reflected repeatedly by the surfaces 3a, 3b, and emitted in the certain direction when it becomes incident to the surface 3b within the critical angle. Because the surface 3a is processed in the form of prism, the surfaces of the fluorescent substance 6 can be enlarged. This increases the emission light in the normal direction to the lamp front surface, improves the directionality, and enhances the light emitting efficiency of the fluorescent substance 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat fluorescent lamp used as, for example, a back light source of a liquid crystal display device, and more particularly to a flat fluorescent lamp in which light in a direction normal to a front surface of the lamp is amplified.

[0002]

2. Description of the Related Art A conventional flat fluorescent lamp is shown in FIG.
As shown in the perspective view and the cross-sectional view of FIG. 5, there is provided an airtight container in which the front glass panel 3, the frame glass 4 and the rear glass panel 5 are bonded to each other with frit glass.

On the inner surface of the front glass panel 3, a phosphor 6 and a metal back layer constituting the anode 7 are sequentially laminated. The anode 7 is formed by depositing a conductor such as aluminum by a thin film forming method such as vapor deposition, sputtering, or ion plating, and a high voltage can be applied via the lead 8.

Mesh-shaped control electrodes 9 and 10 for controlling an electron beam are arranged in parallel in the space inside the closed container 1. The control electrodes 9 and 10 are frit glass 11.
Is adhered and fixed to the frame glass 4.

Between the control electrodes 9 and 10 and the rear glass panel 5 is a cathode group 1 composed of a plurality of line-shaped cathodes.
2 is supported so as not to sag by applying a constant tension by the conductive support portions 13a and 13b having a spring property.

A back electrode 14 made of a conductive film such as carbon is formed on the inner surface of the back glass panel 5.

In this flat fluorescent lamp, a voltage is applied to the cathode group 12 through the conductive lead portions 15a and 15b and the conductive support portions 13a and 13b, and the heater is heated by the heater to emit an electron beam. This electron beam is made uniform by the back electrode 14 and controlled by the control electrodes 9 and 10 provided on the cathode group 12, and
It is accelerated by the high voltage applied to the anode 7 of the front glass panel 3 and rushes into the phosphor 6 to excite the phosphor 6 to emit light.

[0008]

The light emitted by the light emission of the phosphor 6 of this conventional flat fluorescent lamp is diffused light and has no directivity. Therefore, when light in a predetermined narrow angle range is required, such as the back light source of a liquid crystal panel,
It is inefficient because it eliminates the need for light traveling in other directions. Further, since the phosphor 6 is flat, there is a limit to increase the surface area of the phosphor 6, which is disadvantageous in increasing the amount of light emission and increasing the efficiency.

The flat fluorescent lamp according to the present invention has been made in view of the above circumstances, and an object thereof is to provide a flat fluorescent lamp capable of enhancing the directivity of emitted light.

[0010]

The flat fluorescent lamp of the present invention is a flat fluorescent lamp having a fluorescent film formed on the inner surface of a front glass panel, wherein the outer surface of the front glass panel is formed in a prism shape. And

Further, in order to achieve the above object, the inner surface side of the front glass panel may be formed in a prism shape.

[0012]

[Function] By processing the outer surface side of the front glass panel into a prism shape, of the light reaching the outer surface of the front glass panel, the light incident on the outer surface at an incident angle within a certain critical angle is refracted on the outer surface. Then, the light is emitted from the front surface of the front glass at a normal direction or at an angle close thereto, but when the incident angle with respect to the outer surface exceeds the critical angle, the light is totally reflected inside the front glass and the inner surface of the front glass or the phosphor. Will be reflected again. When the light is incident on the outer surface at an angle of incidence within the critical angle while repeating reflection on both surfaces of the front glass, the light is emitted in front of the front glass.

Further, if the inner surface side of the front glass is processed into a prism shape, the surface area of the phosphor formed on this inner surface can be made larger than that of the flat inner surface.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The flat fluorescent lamp according to one embodiment of the present invention will be described in detail with reference to the drawings.

As shown in the schematic view of FIG. 1, an outer surface 3b and an inner surface 3a of a front glass panel 3 of this flat fluorescent lamp are processed into a prism shape, and a phosphor 6 and an anode 7 are sequentially formed on the inner surface 3b as compared with a conventional example. Stacked in the same way.

In this flat fluorescent lamp, as shown in the explanatory views of FIG. 2 and FIG. 3, of the light incident on the outer surface 3b from the inner surface 3a side of the front glass panel 3, its incident angle θ.
The light A within a predetermined critical angle passes through the outer surface 3b and is emitted to the front surface of the lamp in the normal direction or a direction close thereto.

On the other hand, of the light incident on the outer surface 3b from the inner surface 3a side of the front glass panel 3, its incident angle θ.
The light B whose angle exceeds a predetermined critical angle is totally reflected inside the front glass panel 3 by the outer surface 3b and repeatedly reflected by the other outer surface 3b and the inner surface 3a until a critical angle is reached at any point on the outer surface 3b. When the light enters within the range, the light is emitted in the direction normal to the front surface of the lamp or a direction close thereto. That is, as shown by the hatched portion in FIG. 3, the light is emitted in the direction normal to the front surface of the lamp or a direction close thereto. Further, by forming the inner surface 3a of the front glass panel into a prism, the light reflected by the outer surface 3b is largely diffused by the inner surface 3a, so that the light re-enters the outer surface 3b at an angle within the critical angle, and On the other hand, a large amount of light is emitted in the normal direction or a direction close thereto.

The inner surface 3a of the front glass panel 3
By forming a prism shape, the surface area becomes larger than the projected area, and the surface area of the phosphor 2 formed on the inner surface 3a also becomes larger. Therefore, the light emitting area that can emit light by the rush of electrons is increased, and the light emitting efficiency can be improved.

The other constructions, functions, and effects of this flat fluorescent lamp are the same as those of the above-mentioned conventional example, and therefore their explanations are omitted to avoid duplication.

[0020]

As described above, according to the flat fluorescent lamp of the present invention, by forming the outer surface of the front glass panel in a prism shape, the light emitted in the normal direction to the front surface of the lamp is increased. As a result, a flat fluorescent lamp that is optimal as a light source that requires directivity, such as a background light source of a liquid crystal display device, can be obtained.

Further, by forming the inner surface of the front glass panel in a prism shape, the area of the inner surface and the phosphor 6 formed on the inner surface can be made larger than the projected area of the inner surface, and the luminous efficiency of the phosphor is improved. Can be increased.

[Brief description of drawings]

FIG. 1 is a schematic view of a front glass panel according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an optical path of the flat fluorescent lamp of the present invention.

FIG. 3 is an explanatory diagram showing a distribution of outgoing light in the outgoing direction of the present invention.

FIG. 4 is a perspective view of a conventional example which is a premise of the present invention.

FIG. 5 is a sectional view of a conventional example which is a premise of the present invention.

[Explanation of symbols]

 3 front panel 3a inner surface 3b outer surface 5 back panel 6 phosphor 7 anode 9, 10 mesh electrode 12 cathode group 14 back electrode

Claims (2)

[Claims] 1. A flat fluorescent lamp in which a fluorescent film is formed on the inner surface of a front glass panel, wherein the outer surface side of the front glass panel is formed in a prism shape. 2. The flat fluorescent lamp according to claim 1, wherein an inner surface side of the front glass panel is formed in a prism shape.