JP2958671B2 - Flat light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal television, a word processor,
The present invention relates to a flat light emitting device used as a light source for a display screen of a personal computer or the like.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional flat light emitting device forms an outer periphery with a spacer 3 which secures and surrounds an internal space between a transparent flat plate member A1 and a transparent flat plate member B2. It is evacuated and sealed with argon gas and mercury.
Then, the phosphors A8 and B7 were applied to the inner surfaces of the two transparent flat plate members A1 and B2 by screen printing, respectively. At this time, the phosphor A8 and the phosphor B7 had the same thickness. The principle of light emission of this flat light emitting device is that electrons emitted from a cathode repeatedly collide with mercury and argon molecules to generate ultraviolet rays, and the ultraviolet rays excite a phosphor to emit light (exhaust port). And electrodes are omitted in the figure).

FIG. 3 is a partial cross-sectional view of a liquid crystal display device before the appearance of the flat light emitting device. The light emitted from the round fluorescent tube 12 is guided from the side surface of the light guide plate 15 to irradiate the transmissive display panel 17 as a surface light source that is as uniform as possible. Here, the light is applied to the inner surface of the round fluorescent tube 12. The phosphor 13 is open only on the light guide plate 15 side (not coated). This is to prevent the above-mentioned phenomenon that the visible light excited by the ultraviolet rays is re-absorbed by the phosphor 13 and attenuated while passing through the phosphor 13, so that the phosphor 13 is particularly limited only to the portion where light is to be led. It is a method of not applying.

[0004]

Turning now to FIG. 2, the phosphor B7 coated on the inner surface of the transparent flat plate member 2 will be described.
When the light is excited by ultraviolet rays to emit light, the direct light 10 is considerably attenuated when passing through the phosphor A8 on the opposite side, so that there is a problem that the luminous efficiency is not improved as desired.

[0005]

[MEANS FOR SOLVING THE PROBLEMS] It comprises two flat members, a spacer for securing and enclosing the internal space between the flat members, an electrode, a gas sealed in the internal space, a phosphor and the like. In the flat light emitting device, a phosphor is applied to one of the inner surfaces of the plate members and the spacer, and the phosphor is not applied to the plate member on the emission side from which generated light is emitted. Features.

[0006]

FIG. 1 (a) is a main sectional view showing a reference example of a flat light emitting device according to the present invention, wherein 1 is a transparent flat plate member, 2 is a transparent flat plate member B, and 3 is an internal space. 6 is an enclosed gas such as argon or mercury, 7 is a phosphor B,
Reference numeral 9 denotes a reflecting plate (which may be a seal), 10 denotes direct light generated by being excited by ultraviolet rays, and 11 denotes reflected light (reflected by the reflecting plate).

FIG. 1B is a plan view showing a reference example of the flat light emitting device according to the present invention. Reference numeral 4 denotes electrodes (both ends);
Reference numeral 5 denotes an exhaust port, and 7 denotes a phosphor B.

In FIGS. 1A and 1B, when a high-voltage pulse for generating a discharge is applied to both ends of an electrode 4, electrons jump out of the electrode, and the electrons repeatedly collide with mercury and argon molecules. As a result, ultraviolet rays are generated, and the phosphors 7 are excited by the ultraviolet rays to emit light. For example, the direct light 10 emitted here is applied to the transparent plate member A1 opposed to the phosphor, as in the related art. Since it is transparent and does not decay, it hardly attenuates. The light emitted in the opposite direction from the phosphor B7 is reflected by the reflector 9 and attenuated when passing through the phosphor B7 again, but thereafter, the reflected light 11 is obtained without being attenuated similarly to the direct light 10. . In other words, applying the phosphor to both insides of the two transparent flat members negates and attenuates each other because the required light emitting surface is single-sided in terms of luminous efficiency at the cost, and the total is reduced. Not a good way.

If the transparent plate member on one side remains transparent as in this configuration and the phosphor is applied thickly on the inner surface of the other transparent plate member, the light is directly increased and the necessary light emission is effectively obtained with almost no attenuation. The surface can be illuminated. Conversely, in FIG. 1A, the required light emitting surface is assumed to be upward, the fluorescent pair B7 is applied thickly only on the inner surface of the lower transparent flat plate member B2, and the reflecting plate B is disposed on the lower surface. However, a thin phosphor is applied to the inner surface of the upper transparent plate member A1,
A method in which the lower transparent plate member B2 remains transparent and a reflecting plate is disposed on the lower surface thereof can be said to be effective.

Returning to the prior art example of FIG. 3 described above, it is difficult to provide an opening in the inner surface of the round fluorescent tube 12 and apply the phosphor 13, and the cost is greatly increased. It is not actually used at the mass production level. However, since the flat light emitting device is a flat type and the required light emitting surface is one side, by using the transparent flat plate member on one side as it is, it is possible to obtain effects in both cost reduction and improvement in luminous efficiency. And its configuration is completely different.

4 and 5 are sectional views showing another embodiment of the flat type light emitting device of the present invention. In both figures, 1 is a transparent plate member A, 2 is a transparent plate member B, 3 is a spacer. , 8 is a fluorescent substance A, 7 is a fluorescent substance B, 6 is a sealing gas such as argon and mercury. In FIG. 4, the thickness of the phosphor A8 applied to the transparent plate member A1 is thicker at the center and gradually thinner toward the outer periphery. This is one of the means for obtaining a more uniform surface light source, even though it is a flat type light emitting device, because the surface has uneven brightness. In other words, it is possible to attenuate light by increasing the thickness of the phosphor in a place that is too bright, and conversely, in a dark place, make the phosphor thinner to emit light and reduce the attenuation.

In FIG. 5, the phosphor A8 has a pattern in which holes are partially formed by screen printing or the like. This is for allowing the direct light from the phosphor B7 to pass and for causing the phosphor A8 itself to emit light. In addition, it is possible to make a large hole in a dark place according to the luminance unevenness on the surface of the flat light emitting device, and to enlarge the area of the phosphor A8 in a bright place. Of course, if an excessively large hole is formed or an extreme pattern is formed, the pattern may appear on the screen. However, in most cases, the pattern is not recognized because it is just above the light emitting surface and passes through a liquid crystal panel or the like.

A method combining FIG. 4 and FIG. 5 is also conceivable, and the surface for adjusting the application state of the phosphor may be obtained on either side or on both sides.

Next, FIG. 6 is a sectional view showing an embodiment of the flat light emitting device of the present invention.
8 is applied. With this configuration, the light emitted from the phosphor B7 on the lower surface and the phosphor 18 on the side surface passes through the transparent flat plate member 1 (still transparent) on the emission side from which the generated light is emitted, and is effective without attenuation. Light can be irradiated.

Finally, FIG. 7 is a cross-sectional view when the flat light emitting device is applied to a liquid crystal display device, wherein 21 is a flat light emitting device, 17 is a transmissive display panel, 19 is an upper polarizing plate, 20
Is a lower polarizing plate, 22 is a panel circuit board, 23 is a fixed frame, 2
4 is an upper shield plate, 25 is a lower shield plate, 26 is an upper case, 27 is a lower case, and 28 is a cover glass. By having this flat light-emitting device, components such as a reflector and a diffuser used in a conventional liquid crystal display device become unnecessary, and the thickness of the entire device can be reduced, and a high-quality image having a uniform surface light source can be obtained. A liquid crystal display device is realized.

Here, the lower polarizing plate 20 is generally attached to the back surface of the transmissive display panel 17 or attached to the surface of a diffusion plate. However, the polarizing plate absorbs heat and transmits light. When pasted on the display panel 17, the temperature is transmitted to the transmission display panel 17 and the display quality is degraded. In addition, since the diffusion plate is a very thin part and has no strength, it always has a problem that it is deformed or contains air bubbles after the polarizing plate is attached. In FIG. 7, the lower polarizing plate 20
Is adhered to the surface of the flat light emitting device 21 to secure a clearance from the transmissive display panel 17. The flat light-emitting device 21 is rigid and easy to stick, and also heats the lower polarizing plate 2.
Since 0 is absorbed, the display quality of the transmissive display panel 17 is very stable.

[0017]

As described above, according to the present invention, two flat members, a spacer for securing and surrounding an internal space between the flat members, an electrode, and a gas sealed in the internal space are provided. In a flat light-emitting device made of a phosphor or the like, a phosphor is applied to one of the inner surfaces of the plate members and the spacer, and a phosphor is provided on the emission-side flat plate member from which generated light is emitted. By not being applied, the generated light is suppressed from attenuating when passing through the phosphor, increasing the luminous efficiency and reducing the cost.Also, applying the phosphor to the inner surface of the spacer, The luminous efficiency can be further improved.

[Brief description of the drawings]

1A and 1B are views showing a reference example of the flat light emitting device of the present invention, wherein FIG. 1A is a main sectional view, and FIG. 1B is a plan view.

FIG. 2 is a main cross-sectional view showing a conventional flat light emitting device.

FIG. 3 is a partial cross-sectional view showing a conventional liquid crystal display device.

FIG. 4 is a sectional view showing another reference example of the flat light emitting device of the present invention.

FIG. 5 is a sectional view showing another reference example of the flat light emitting device of the present invention.

FIG. 6 is a sectional view showing an embodiment of the flat light emitting device of the present invention.

FIG. 7 is a cross-sectional view illustrating an example in which a flat light-emitting device is applied to a liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent flat plate member A 2 Transparent flat plate member B 3 Spacer 4 Electrode 5 Exhaust port 6 Gas 7 Phosphor B 8 Phosphor A 9 Reflector 10 Direct light 11 Reflected light 12 Round fluorescent tube 13 Phosphor 14 Light ray A 15 Light guide plate Reference Signs List 16 light beam 17 transmissive display panel 18 phosphor 19 upper polarizing plate 20 lower polarizing plate 21 flat light emitting device 22 panel circuit board 23 fixing frame 24 upper shield plate 25 lower shield plate 26 upper case 27 lower case 28 cover glass

Claims (1)

(57) [Claims] 1. A flat light-emitting device comprising two flat members, a spacer for securing and surrounding an internal space between the flat members, an electrode, a gas sealed in the internal space, a phosphor, and the like. Wherein a phosphor is applied to one inner surface of the plate member and the spacer, and the phosphor is not applied to the flat plate member on the emission side from which generated light is emitted. Type light emitting device.