JPH0212750A - Planar fluorescent lamp - Google Patents

Abstract

PURPOSE:To realize a thin form and a light weight and to expand the effective luminous area by inclining the inner surface of a spacer in a specific angle to oppose to the inner surface of a front plate. CONSTITUTION:Spacer elements 23a are composed to make the width of the lower side contacting to the outer edge of a rear side plate 22 larger than the width of the upper side contacting to the outer edge of a front side plate 21. Since the width of one end of a spacer 23 contacting to the rear side plate 22 is expanded by the inclined surface of the inner surface of the spacer 23 in such a way, the contact area of the spacer 23 and the rear side plate 22 is expanded, and the stress to the outer air pressure of the rear side plate 22 is reduced. Consequently, the thickness of the rear side plate can be made smaller than that of the front side plate, a thin form and the light weight of the whole unit are realized, and the effective luminous area is expanded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a planar fluorescent lamp suitable for backlighting a liquid crystal display panel such as a liquid crystal television from the back side. This invention relates to a planar fluorescent lamp with an improved spacer.

(Prior art) In recent years, LCD televisions have been developed and are becoming more popular, but this type of LCD television requires an LCD panel to display the TV screen and a backlight to illuminate the panel from the back. Therefore, the function of illuminating the entire display surface of a predetermined area with a certain brightness is required.

Conventionally, such backlights are made by arranging multiple U-shaped fluorescent lamps or small straight tube fluorescent lamps in parallel, and combining them with light reflecting surfaces, light diffusing surfaces, etc.
Some devices are designed to obtain various brightness distributions.

However, when using multiple fluorescent lamps like this, it is inevitable that the brightness near the lamps will be higher than other areas, and it is difficult to eliminate overall brightness unevenness. .

In addition, since multiple fluorescent lamps are used, the structure for holding these lamps and the structure for connecting the power supply becomes complicated, which increases the number of parts, increases the size of the device, and in particular increases the thickness of the backlight itself. There is a drawback that it cannot be formalized.

As a solution to this problem, the
11198! A planar fluorescent lamp (hereinafter referred to as a planar fluorescent lamp) as shown in Publication Ill has been proposed.

This planar fluorescent lamp is constructed as shown in FIGS. 8 to 11, and includes a front plate 1 made of a single transparent glass plate, a back plate 2 made of a single glass plate of the same shape and size, It has a glass spacer 3 assembled into a rectangular frame of the same shape and size as these plates 1.degree.2.

The front plate 1 has a fluorescent film 4 coated almost entirely on its inner surface as shown in FIG. 11, and its outer surface serves as a light emitting surface, and the back plate 2 has a light diffusing film 5 and a light reflecting film on its inner surface. 6 are applied in two layers, upper and lower.

The front plate 1 and the back plates 1 and 2 are provided with low melting point glass frits 7 in the front and back openings of the spacer 3.
They are each airtightly joined to form a thin box-shaped airtight container 8 as shown in FIGS. 9 to 11.

Therefore, the front plate 1 faces the back plate 2 with a spacer 3 in between, and a discharge space 9 is provided between both plates 1.2.
is formed.

In this discharge space 9, a pair of electrodes 10, 10, such as a hollow cathode type cold cathode, are arranged facing each other and spaced apart from each other, and these pair of electrodes 10, 10 are formed in a box shape with an opening-shaped cross section. These mouth-shaped openings are opposed to each other.

Also, a pair? ffl4i10.10 has a pair of lead pieces 11.11 integrally extending outward in the axial direction from one end in the axial direction, and the tip of each lead piece 11 extends airtightly to the outside of the closed container 8, not shown. It is connected to a power source.

Note that reference numeral 12 in FIGS. 8 to 11 is an exhaust pipe, and during discharge, at least one kind of rare gas such as xenon, krypton, argon, neon, helium, etc. In some cases, this rare gas and a predetermined amount of mercury are sealed.

When a predetermined voltage is applied between the pair of electrodes 10.10 in the planar fluorescent lamp configured in this way, a glow discharge is generated between the pair of electrodes 10.10, and this glow discharge causes the airtight container 8 The mercury inside generates ultraviolet light, which excites the fluorescent film 4 of the front plate 1, and visible light is emitted from the light emitting surface on the outer surface of the front plate 1.

Moreover, the ultraviolet rays generated in the closed container 8 are diffused and reflected by the light diffusion film 5 and the light reflection film 5 and guided toward the fluorescent film 4, thereby increasing the luminous efficiency of the fluorescent film 4.

Therefore, the entire front boot 1 emits light almost uniformly, so there is little unevenness in brightness.

(Problems to be Solved by the Invention) However, such conventional planar fluorescent lamps have a problem in that it is not easy to make them thin and lightweight.

That is, in order to expand the effective light emitting area of a planar fluorescent lamp, for example, when increasing the size of the front plate 1, the front plate 1 must be 1, of course, other spacers 3, etc.
It is necessary to increase the thickness of the entire J8, which increases the weight of ff1fu, and has the disadvantage that it goes against the thinness required for backlights.

Furthermore, if the width of the spacer 3 is increased without increasing the thickness of the front plate 1 to increase the strength of the entire sealed container 8, the effective light emitting area of the front plate 1 will be increased by the width of the spacer 3. The disadvantage is that it reduces the

The present invention has been made in consideration of the above circumstances, and its object is to provide a planar fluorescent lamp that can be made thinner and lighter and have an increased effective light emitting area.

[Structure of the invention]

(Means for Solving the Problem) The present invention arranges a back plate facing a light-transmitting front plate, and a frame-shaped spacer is interposed between these two plates to form a discharge space. In the planar fluorescent lamp in which a pair of electrodes are arranged facing each other, the inner surface of the spacer is inclined at a predetermined angle so as to face the inner surface of the front plate.

A second invention is characterized in that at least one of a light-diffusing film and a light-reflecting film is attached to the inclined surface of the spacer of the first invention.

(Function) When a predetermined voltage is applied between the pair of electrodes, a discharge occurs and ultraviolet rays are generated, and this ultraviolet rays directly excite the fluorescent film of the front plate to emit light.

Therefore, according to the first invention, since the width of one end of the subaree to be adhered to the back plate is widened by the inclined surface on the inner surface of the spacer, the contact area between the spacer and the back plate is expanded, and the back plate stress to external pressure is reduced.

Therefore, the thickness of the back plate can be made thinner than that of the front plate, and the overall planar fluorescent lamp can be made thinner and lighter.

Further, according to the second invention, since the inclined surface on the inner surface of the spacer is directed toward the front plate side, the ultraviolet rays are guided to the fluorescent film on the inner surface of the front plate by this inclined surface, improving the luminous efficiency here. let

Therefore, in the front plate, light can be emitted effectively even in the portion corresponding to the inclined surface of the inner surface of the spacer and the surrounding portion thereof, so that the effective light emitting area can be expanded.

(Example) An example of the present invention will be described below based on FIGS. 1 to 5.

FIG. 1 shows an exploded perspective view of an embodiment of the present invention, and this embodiment includes a front plate 21 made of a single transparent plate glass,
A back plate 22 made of a sheet of glass having the same shape and size, a glass spacer 23 assembled into a rectangular frame having almost the same shape and size as these plates 21.22, and a pair of electrodes 24.24. and has.

The spacer 23 is formed by assembling four glass spacer elements 23a, 23a, 23a into a rectangular frame as shown in FIG. 1, and each spacer element 23a forms a trapezoidal column as shown in FIG. The inclined surface S is located inside the rectangular frame of the spacer 23 and is opposed to the inner surface of the front plate 21 at a required angle.

Further, the rectangular frame-shaped spacer 23 has a circular exhaust pipe 25 protruding from the axially intermediate portion of one side thereof, and communicates the inside and outside of the frame of the spacer 23 via the exhaust pipe 25.

As shown in FIGS. 3 and 4, this spacer 23 is
The outer edge of the front plate 21 is airtightly adhered to the front opening end of the front plate 21, and the outer edge of the back plate 22 is airtightly bonded to the rear front end thereof by a low melting glass frit 26, thereby forming an airtight container 27. The inside of the sealed container 27 is the discharge space 2
It is composed of 8.

Therefore, each spacer element 23a
The width of the lower end in the figure, which is bonded to the outer edge of the front plate 21, is wider than the upper end in the figure, which is bonded to the outer edge of the front plate 21.

The front plate 21 also has fluorescent light on its inner surface.
A light-reflecting IF 130 is coated almost entirely on the inner surface of the back plate 22, and a light-emitting surface is formed on the outer surface that emits visible light excited by the fluorescent film 29 to the outside. At the same time, a light diffusing layer 1I31 is entirely coated on the light reflecting film 30.

In addition, this light diffusion film 31 and light reflection [130 upper and lower 2W1
is the slope S of each spacer element 23a as shown in FIG.
It is also entirely coated on the top, so that ultraviolet rays from the horizontal direction are diffused and reflected toward the fluorescent film 29 side of the front plate 21, as shown by the arrows in the figure.

The pair of electrodes 24 are each formed of a hollow cathode type cold cathode each formed into a triangular cylinder shape, as shown in FIG. 1, for example.
The spacer elements 23a have triangular inclined surfaces facing each other in the left-right direction as shown in FIG.

The electrodes 23a are arranged facing each other with a slight gap on the light diffusion ll31 of each inner inclined surface S, and the opposing surfaces of the pair of electrodes 24 are almost completely opened.

A pair of electrodes 24 have lead wires 32.3 at their axial ends.
2 are fixed so as to protrude outwardly and outwardly in the axial direction, and the tips of these lead wires 32 and 32 are passed through the spacer 23 in an airtight manner and extended to the outside so as to be electrically connected to a power source (not shown). It has become.

In the airtight container 29, there is at least one element made of xenon, krypton, argon, neon, helium, etc.
It is filled with a rare gas, or mercury.

Next, the operation of this embodiment will be explained.

When a predetermined voltage is applied between the pair of electrodes 24.24,
Glow discharge occurs in the discharge space 28 between these electrodes 24, 24, and the glow discharge excites rare gas or mercury to generate ultraviolet light.

This ultraviolet light excites the fluorescent film 29 of the front plate 21 to emit visible light, which is transmitted through the front plate 21 and emitted from the light emitting surface on its outer surface.

Further, the ultraviolet rays generated in the discharge space 28 are diffused and reflected by the light diffusion film 31 and the light reflection film 30, and guided to the fluorescent film 29, where they are excited and emit light, thereby increasing the luminous efficiency.

Then, on the inside of the pair of spacer elements 23a, front and rear in FIG. The light is diffused and reflected by the light diffusing film 31 and the light reflecting film 30 on the front plate 21 above.
The fluorescent film 29 is excited, and visible light is emitted from the light emitting surface on the outer surface of the front plate 21.

Therefore, the outer edge portion of the outer surface of the front plate 21 above the inclined surface S of the spacer elements 23a, 23a also becomes an effective light emitting surface for emitting visible light, and this effective light emitting surface is also formed by the inclined surface S of the pair of spacer elements 23a. Since the light exists over the entire length of the light emitting area, the effective light emitting area can be expanded.

Further, as shown in FIGS. 4 and 5, each spacer element 23a is formed into a trapezoid shape tapering from the bottom surface in the figure where it is bonded to the back plate 22 to the top surface in the figure where it is bonded to the front plate 21. Since the width of the lower surface of each spacer element 23a is wider than the width of the upper surface, the thickness of the back plate 22 bonded to the lower surface of each spacer element 23a is made thinner than the thickness of the front plate 21. Therefore, it is possible to achieve a thinner and lighter weight and a reduction in the amount of material.

That is, as shown in FIG. 6, the maximum stress on the front plate 21 and the back plate 22 due to the external pressure is
The maximum stress of the back plate 22 is reduced as the width of the upper and lower surfaces of the back plate 22 is increased and the bonding area is increased. The thickness of the plate can be reduced, and the thickness and weight of the plate can be reduced accordingly.

As an example, in a planar fluorescent lamp used as a backlight for a 6.5-inch LCD TV shown in FIGS. 8 to 11, the front plate 21 and back plate 22 are both 140 ), plate thickness 5 (#l
11) plate glass is used, and the spacer 23
The total thickness of the sealed container 29 including the container was 13 (am+), and the weight was approximately 5,009 mm.

On the other hand, in this embodiment, the thickness of the back plate 22 can be reduced to 2 m+ compared to the above-mentioned conventional example, so the thickness of the entire sealed container 27 is 10 (m 2 ), and the weight is approximately 42 Cl. It can be made lighter.

In addition, in the above embodiment, the inclined surface S of each spacer element 23a
Although the case where the spacer element 23a is formed as a flat surface has been described, the present invention is not limited to this. For example, as shown in FIG. 7, the inclined surface 5a of each spacer element 23a may be formed as a concave arc-shaped curved surface. .

〔Effect of the invention〕

As explained above, in the present invention, the inner surface of the spacer is formed into an inclined surface so as to face the inner surface of the front plate having a fluorescent film, and the width of one end of the spacer adhered to the outer edge of the back plate is inward. Since the width is widened by the inclined surface, the bonding area of both bonding parts is expanded, and the maximum stress on the back plate due to external pressure can be reduced, and the thickness of the front plate can be reduced accordingly, making it lighter. can be achieved.

In addition, since at least one of a light diffusion film and a light reflection film is coated on the inclined surface of the inner surface of the spacer, this inclined surface guides ultraviolet rays to the fluorescent film on the outer edge of the front plate, where they can be emitted. can.

That is, since the effective light emitting surface can be expanded to the outer edge of the front plate h, the effective light emitting area of the entire planar fluorescent lamp can be expanded.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of one embodiment of a planar fluorescent lamp according to the present invention, FIG. 2 is a perspective view of one spacer element shown in FIG. 1, and FIG. 3 is an embodiment of the embodiment shown in FIG. 1. 4 is a sectional view taken along the line IV-IV in FIG. 3, and FIG.
■An end view in the direction of arrows, Figure 6 is a graph showing the correlation between the width of a general spacer and the maximum stress due to external pressure on the front plate and back plate bonded to this spacer, and Figure 7 is a graph showing the correlation between the width of a general spacer and the maximum stress due to external pressure on the front plate and back plate bonded to this spacer. FIG. 8 is an exploded perspective view of a conventional planar fluorescent lamp; FIG. 9 is a plan view showing the assembled state of the conventional example shown in FIG. 8; FIG. is a front view of FIG. 9, and FIG. 11 is a sectional view taken along the line XI-XI in FIG. 21...Front plate, 22...Back plate, 2
3... Spacer, 23a... Spacer element, 24.
... Electrode, 27 ... Sealed container, 29 ... Fluorescent film, 3
0... Light reflecting film, 31... Light diffusing film, S, Sa...
・Slope surface.

Claims (1)

[Claims] 1. A light-transmitting front plate and a rear plate are arranged opposite each other, a frame-shaped spacer is interposed between these two plates to form a discharge space, and a pair of electrodes are installed in this discharge space. A planar fluorescent lamp arranged opposite to each other, wherein the inner surface of the spacer is inclined at a predetermined angle so as to face the inner surface of the front plate. 2. A planar fluorescent lamp characterized in that the inclined surface according to claim 1 is coated with at least one of a light-diffusing film and a light-reflecting film.