JPH08273603A - Plane fluorescent lamp - Google Patents

Abstract

PURPOSE: To provide high compressive strength and actualize uniform brightness distribution in a light emitting face in a plane type fluorescent lamp in which discharge is carried out between both electrodes. CONSTITUTION: In a closed container 1, one or a plurality of strips of pressure- proof reinforcing ribs 21 which are extended in the direction at right angles to the direction of discharge between electrodes 4, 4 are projected toward one glass panel 3 from the other glass panel 2 and a plurality of aperture parts 22 penetrated in the discharge direction are formed at a distance one another in the pressure-proof reinforcing ribs 21.

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 suitable as a backlight for liquid crystal displays and the like.

[0002]

2. Description of the Related Art A liquid crystal display is widely used as an image display device, and a cold cathode type flat fluorescent lamp is used as its backlight. The flat fluorescent lamp is also becoming larger along with the recent increase in the size of the liquid crystal display.

Particularly in a large flat fluorescent lamp, it is necessary to increase the thickness of the glass plate forming the discharge space to ensure sufficient pressure resistance. However, this causes a problem that the weight of the flat fluorescent lamp increases. Therefore,
It has been proposed to interpose a spacer between the front glass panel and the rear glass panel to ensure pressure resistance.
(ITJ Technical Report Vol.12 No.15 (issued March 25, 1988) pages 49-54). However, in a flat fluorescent lamp equipped with a spacer, the shadow of the spacer is reflected on the light emitting surface,
There is a problem that striped uneven light emission occurs.

On the other hand, in the flat fluorescent lamp shown in FIGS. 4 and 5, the front panel (7) and the rear panel (8) are joined to each other by the frit glass (11) to form a flat sealed container.
(6) is constructed and the inside is evacuated using the exhaust pipe (12).
Multiple pressure resistant reinforcement ribs (7) that reach the inner surface of the rear panel (8)
1) is integrally molded, and the discharge space is divided into a plurality of cells. In the flat fluorescent lamp, the rib (71)
A pair of electrodes (9) and (9) are arranged on both sides in the longitudinal direction of the cell, and by applying a voltage to both electrodes (9) and (9), discharge is generated in each cell.

In the above-mentioned flat fluorescent lamp, the upper surface of the pressure-proof reinforcing rib (71) is formed by a curved surface recessed in a wedge shape as shown in the drawing, and the curved portion including the curved surface forms a rear panel.
The rib (71) exerts the function of a condenser lens that refracts a light beam emitted vertically from (8) toward the center side of the rib (71).
To eliminate the shadow of (Japanese Patent Application No. 4-241944 [H01J61 /
30)).

[0006]

However, in the flat fluorescent lamp shown in FIGS. 4 and 5, the rib (71) is used.
Although the shadow of the rib (71) was almost disappeared due to the curved surface shape, there was still a problem that uneven light emission occurred in the peripheral portion of the rib (71). The cause is that in the flat fluorescent lamp, the discharge space is divided into a plurality of cells, and the rib (71)
It is considered that this is because the structure in which the discharge is generated along the longitudinal direction of (1) causes the wall resistance of the tube to increase as the discharge approaches the side wall of the rib (71), and the current density of the discharge decreases. Due to the decrease in the current density, the amount of ultraviolet rays generated in the vicinity of the ribs (71) is decreased, and the brightness is decreased as compared with the central part of each cell.

An object of the present invention is to provide a flat fluorescent lamp which has a high pressure resistance and can obtain a uniform luminance distribution.

[0008]

In the flat fluorescent lamp according to the present invention, two glass panels (2) and (3) are joined to each other to form a flat sealed container (1). Fluorescent film (5) on the inner surface
And a pair of electrodes inside the sealed container (1).
(4) (4) is arranged so as to face each other, and discharge is performed between both electrodes. Here, the sealed container (1) includes one or a plurality of pressure resistant reinforcing ribs (2) extending in a direction intersecting with the discharge direction.
1) is from one glass panel (2) to the other glass panel
A plurality of openings (22) projecting toward (3) are formed at intervals in the pressure-proof reinforcing rib (21) so as to penetrate in the discharge direction.

In a specific structure, the pressure-proof reinforcing rib (21) is integrally formed on one glass panel (2), and the joint between the pressure-proof reinforcing rib (21) and the one glass panel (2) is On both sides of the pressure-resistant reinforcement rib (21), the other glass panel
A lens portion is formed for refracting the light beam vertically emitted from (3) toward the center side of the pressure-resistant reinforcing rib (21).

Further, the fluorescent film (5) has two glass panels.
(2) and (3) are formed on both facing surfaces facing each other with a space therebetween, and on both facing surfaces facing each other with the opening portion (22) of the pressure resistant reinforcing rib (21) interposed therebetween.

[0011]

In the flat fluorescent lamp of the present invention described above, the discharge space is divided into a plurality of cells by the pressure-proof reinforcing ribs (21), and when the discharge is performed between the pair of electrodes (4) (4), The discharge running from the electrode (4) crosses the cell one after another through the opening (22) of the pressure reinforcing rib (21) and reaches the other electrode (4). Therefore, the current density during discharge is as follows:
Although it depends on the tube wall resistance in the vicinity of the opening (22), the current density is the same in the central portion of each cell and the opening (22) of the pressure-proof reinforcing rib (21). As a result, in the vicinity of the central portion of each cell and the pressure-resistant reinforcing ribs (21), the conventional uneven light emission is eliminated, and a uniform luminance distribution is obtained over the entire light emitting surface.

Further, in the concrete construction in which the lens portion is formed at the joint portion between the pressure-proof reinforcing rib (21) and the one glass panel (2), the light beam emitted vertically from the other glass panel (3). The pressure-resistant reinforcing ribs (21) are refracted toward the center side, and light is collected in a region behind the pressure-resistant reinforcing ribs (21). As a result, a more uniform brightness distribution can be obtained.

In addition to the two opposing surfaces of the two glass panels (2) and (3) facing each other with a space therebetween, the pressure-proof reinforcing ribs (2
On both facing surfaces facing each other across the opening (22) of 1),
In the specific structure in which the fluorescent film (5) is formed, the non-luminous region is suppressed to the minimum and a more uniform brightness distribution can be obtained.

[0014]

According to the flat fluorescent lamp of the present invention,
By forming the pressure-proof reinforcing ribs (21), the pressure-proof strength is increased, and at the same time, forming the openings (22) in the pressure-proof reinforcing ribs (21),
By realizing the discharge across each cell, a uniform luminance distribution is realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a large-sized cold cathode type flat fluorescent lamp will be described in detail below with reference to the drawings. FIG.
In the flat fluorescent lamp of the present invention, as shown in FIG. 2, the front glass panel (2) and the rear glass panel (3) are joined by the frit glass (11) to form the flat sealed container (1),
The inside of the sealed container (1) is evacuated using the exhaust pipe (12).

A pair of electrodes (4) is provided inside the sealed container (1).
(4) are arranged oppositely, each electrode (4) is connected to an external lead (41), and a pulse voltage is applied from the external lead (41) (41) to both electrodes (4) (4). Discharge is generated. Also, the front glass panel (2) and the rear glass panel
A fluorescent film (not shown) is formed on the inner surface of (3). The light emitting surface is formed to have a diagonal size of 4 to 5 inches or more.

The inner surface of the front glass panel (2) has electrodes
Plural pressure resistant ribs (2) extending parallel to the longitudinal direction of (4)
1) is integrally formed, whereby the discharge space is divided into a plurality of cells. Each pressure-proof reinforcement rib (21)
A plurality of openings (22) are formed at regular intervals.
For example, the openings 22 have a width of 5 mm and are repeatedly formed at a pitch of 6 mm.

When a discharge is generated between both electrodes (4) and (4) by applying a predetermined voltage, the discharge path extending from one electrode (4) is successively passed through the opening (22) of the pressure resistant reinforcing rib (21). Cross the cell to the other electrode (4). Therefore, the current density at the time of discharge depends on the tube wall resistance in the vicinity of the opening (22) of the pressure-proof reinforcing rib (21).
The opening (22) of 1) has the same current density. In the non-opening portion of the pressure-proof reinforcing rib (21), a discharge path that goes around to the opening portion (22) side is formed without blocking the discharge passage. As a result, a uniform luminance distribution is obtained over the entire light emitting surface.

The front glass panel (2) is as shown in FIG.
The outer surface S of the pressure-proof reinforcing rib (21) is formed by a curved surface recessed in a wedge shape, and the inner side surface T of the pressure-proof reinforcing rib (21) is formed by a curved surface corresponding to the outer surface S. These curved surfaces S and T exert the function of a condenser lens for refracting the light rays vertically emitted from the rear glass panel (3) toward the center side of the rib (21) as shown by the chain line, and the ribs The shadow of (21) disappears.

By the way, the front glass panel (2) is given the curved shape shown in FIG. 3 by using a forming die. The forming die has the deepest portion of the wedge-shaped curved surface of the front glass panel (2). Therefore, it is necessary to form a sharp pointed protrusion.
However, due to the machining accuracy of the mold, the protrusions are blunted to some extent, and this partially impairs the function of the condenser lens, and the shadow of the pressure-resistant reinforcing ribs (21) is on the light emitting surface. It will appear linearly.

In order to obtain a uniform luminance distribution even in such a situation, in this embodiment, as shown in FIG. 3, all the facing surfaces of the front glass panel (2) and the rear glass panel (3),
That is, the fluorescent film is also formed on both facing surfaces facing each other with the opening (22) interposed therebetween.
(5) is formed. As a result, irrespective of the lens effect that the pressure withstanding ribs (21) should exhibit, light can be emitted from the region where the pressure withstanding ribs (21) are formed, and a more uniform luminance distribution can be realized.

The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or limiting the scope. The configuration of each part of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims. For example, the electrodes to be placed inside the sealed container are not limited to the example in which a pair of electrodes are arranged opposite to each other at both ends of the discharge space, but an intermediate electrode is also placed at the central part of the discharge space so that the potential distribution gradient in the discharge space is It is also possible to adopt a configuration that alleviates.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a flat fluorescent lamp according to the present invention.

FIG. 2 is a sectional view taken along line AA and line BB in FIG.

FIG. 3 is an enlarged cross-sectional view in the vicinity of a pressure-proof reinforcing rib.

FIG. 4 is a perspective view of a conventional flat fluorescent lamp.

5 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

 (1) Sealed container (2) Front glass panel (21) Pressure-proof reinforcing rib (22) Opening (3) Rear glass panel (4) Electrode

Claims (3)

[Claims] 1. A flat sealed container (1) is formed by joining two glass panels (2) and (3) together, and a fluorescent film (5) is formed on the inner surface of the sealed container (1) and sealed. In a flat fluorescent lamp in which a pair of electrodes (4) and (4) are arranged inside the container (1) so as to face each other, a sealed container (1) has a direction intersecting with the discharge direction. One or a plurality of pressure-proof reinforcing ribs (21) extending in the direction of projection are provided from one glass panel (2) toward the other glass panel (3), and the pressure-proof reinforcing ribs (21) are
The flat fluorescent lamp is characterized in that a plurality of openings (22) penetrating in the discharge direction are formed at intervals. 2. The pressure-resistant reinforcing rib (21) is provided on one glass panel.
The pressure-resistant reinforcing rib (21) is integrally formed with the glass panel (2), and the glass panel (3) on the other side is sandwiched by the pressure-resistant reinforcing rib (21). 2. The flat fluorescent lamp according to claim 1, further comprising a lens portion for refracting a light beam emitted vertically from the light pressure reinforcing rib toward the center side of the rib. 3. The fluorescent film (5) comprises two glass panels (2).
The (3) is formed on both opposing surfaces facing each other with a space therebetween, and on both opposing surfaces facing each other with the opening portion (22) of the pressure-proof reinforcing rib (21) interposed therebetween. The flat fluorescent lamp described.