JPH07105709A - Lighting device, backlight and liquid crystal display device - Google Patents

Abstract

(57) [Abstract] [Purpose] To shield electromagnetic radiation noise and to downsize the entire device. [Structure] At least an electrodeless discharge lamp 14, a lighting circuit 15 for lighting the lamp 14 at a high frequency, and a light guide body 13 are housed together in a case 12 which is capable of electromagnetic shielding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device suitable for a backlight for illuminating a liquid crystal display panel from the back by an electrodeless discharge lamp which is lit at a high frequency, and particularly to reduce electromagnetic radiation noise. The present invention relates to a lighting device, a backlight, and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, this type of liquid crystal display panel (hereinafter referred to as L
As an example of a lighting device such as a backlight for illuminating a CD panel), an LCD panel (not shown) is arranged directly above a light guide made of acrylic resin or the like, and a plurality of electrodeless electrodes are provided directly below the light guide. Discharge lamps are arranged, and light from these electrodeless discharge lamps is applied to the light guide body to emit light in a planar manner, thereby illuminating the entire LCD panel substantially evenly.

However, since the electrodeless discharge lamp is lit at a high frequency by an inverter or the like (not shown), electromagnetic waves may be emitted from the electrodeless discharge lamp and its lighting circuit to the outside to cause noise in peripheral equipment.

For this reason, a method of covering the entire electrodeless discharge lamp with a shield member can be considered. However, this shields the light from the electrodeless discharge lamp with the shield member, so that the efficiency of the fixture is significantly reduced.

Therefore, conventionally, as shown in FIG. 6, the electrodeless discharge lamp 1 and the high frequency lighting circuit 2 are shielded by being surrounded by respective shield members 3 and 4.

[0006]

However, in such a conventional lighting device, since the electrodeless discharge lamp 1 and the like and the high frequency lighting circuit are covered with the respective shield members 3 and 4 to be shielded, the entire device is large. Since the light guide plate 5 is not covered with a shield member in addition to inviting shape and complexity,
There is a problem that the electromagnetic radiation noise shielding effect is insufficient.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to provide an illuminating device capable of easily shielding electromagnetic wave radiation noise and downsizing the entire device. It is to provide a backlight and a liquid crystal display device.

[0008]

The present invention is configured as follows in order to solve the above-mentioned problems.

The invention according to claim 1 of the present application (hereinafter, referred to as the first
The invention of 1) includes at least an electrodeless discharge lamp, a lighting circuit for lighting the lamp at a high frequency, and a light guide for receiving light from the lamp and emitting light in a planar manner.
It is characterized in that it is housed in a case that can freely control two electromagnetic shields.

The invention according to claim 2 of the present application (hereinafter referred to as the second invention) is characterized in that the light guide body is shielded by a translucent electromagnetic shield material.
The invention according to claim 3 of the present application (hereinafter referred to as the third invention) is characterized in that the case is made of a conductor and is grounded.

Furthermore, the invention according to claim 4 of the present application (hereinafter referred to as the fourth invention) illuminates the object to be illuminated from the back side by the illumination device according to any one of claims 1 to 3. It is characterized in that it is configured to.

The invention according to claim 5 of the present application (hereinafter referred to as the fifth invention) is characterized in that the illuminated object is a liquid crystal display panel.

Furthermore, the invention according to claim 6 of the present application (hereinafter referred to as the sixth invention) is characterized in that the illuminated body is an evacuation guidance display board or a display board such as a signboard.

[0014]

Since at least the electrodeless discharge lamp, the light guide, and the lighting circuit are housed in one case, electromagnetic radiation noise can be easily shielded by forming the whole case with a conductor and grounding the case. In addition, the size of the entire device can be reduced.

Further, since the light guide body is shielded by the translucent electromagnetic shield material, it is possible to further enhance the shield effect without lowering the instrument efficiency.

[0016]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a perspective view of an essential part of an embodiment of a lighting device according to the present invention. In the drawing, a lighting device 11 is a lamp case 1 formed of a conductor such as metal into a flat box shape.
2 has a rectangular light guide 13 made of acrylic resin, for example.
And a straight electrodeless discharge lamp 14 which is juxtaposed substantially parallel to and along one side surface of the light guide 13, for example, and a lighting circuit 15 for lighting the lamp 14 at a high frequency. Are arranged side by side and housed together.

In the electrodeless discharge lamp 13, for example, a fluorescent glass film (not shown) is almost entirely adhered to the inner surface of the bulb in a straight tube bulb made of quartz glass without incorporating a discharge electrode.
Mercury is enclosed in the bulb.

The electrodeless discharge lamp 13 has a bulb 1
A pair of left and right external electrodes are provided on the outer surfaces of both axial end portions of 4, and these external electrodes are electrically connected to a lighting device having an inverter, and a predetermined high-frequency voltage is applied to light. There is.

That is, in the electrodeless discharge lamp 13, the enclosed gas in the bulb itself is electromagnetically coupled as a secondary coil by electromagnetic induction from the external electrode, and a plurality of closed loop discharges are uniformly formed in the bulb. For this reason, the enclosed gas in the bulb is excited to generate ultraviolet rays, and the ultraviolet rays excite the phosphor film to emit visible light, and the light distribution is equalized.

Then, the case 12 is formed on the reflecting surface 12b by applying a reflecting material to the inner bottom surface and the side surface of the housing recess 12a for housing the light guide 13 and the electrodeless discharge lamp 14, and guiding the light. LCD on the body 13 as shown by the broken line in the figure.
The panel 16 is placed and fixed.

Therefore, the light guide 13 can receive the light from the electrodeless discharge lamp 14 and the reflecting surface 12b and emit light in a plane, and can illuminate the LCD panel 16 from the back side in a planar manner.

The case 12 is entirely made of a conductor such as metal and grounded to shield the case 12 from electromagnetic noise.

As shown in FIG. 2, the light guide 13 may be constructed so as to shield electromagnetic wave noise by covering the light guide 13 almost entirely with a wire mesh 17, and the light guide 13 may be shielded in the case 12. A shield member may be provided at an appropriate place to shield each member. As a shield material, a transparent conductive mesh member (metal mesh)
And transparent conductive film.

A plurality of heat dissipation step grooves 18 are formed at one end of the case 12 to enhance the heat dissipation of the case 12.

In this embodiment, one case 12 is thus provided.
Since the light guide body 13, the electrodeless discharge lamp 14, and the lighting circuit 15 are housed inside, the size of the entire device can be reduced. Moreover, electromagnetic noise can be easily shielded by grounding the entire case 12.

In the above embodiment, the case of the one-lamp type in which one electrodeless discharge lamp 14 is attached to one side surface of the light guide 13 has been described, but the present invention is not limited to this. It is not a thing, for example, 2 side surfaces of the light guide 13, or 4
An electrodeless discharge lamp may be attached to each side of the side surface to form a two-lamp type or a four-lamp type.

FIG. 3 is a schematic view of a main part of an illuminating device according to another embodiment of the present invention. The illuminating device 21 has a plurality of hemispherical projections 23 integrally formed on the outer bottom surface 22b of the light guide 22. , 2
3, 23 ... are characteristic.

That is, the light guide 22 receives light from the electrodeless discharge lamp 24, the arc-shaped reflection plate 25, and the bottom reflection sheet 26 on the side of the light guide 22, and light-emites it in a planar manner at the light exit surface 22a on the upper surface in the figure. However, the object to be illuminated such as an LCD panel (not shown) above it is illuminated.

The plurality of hemispherical projections 23 are
As the distance from the electrodeless discharge lamp 24 of the light source increases, the projecting density is gradually increased to improve the brightness uniformity.

Therefore, as shown in FIG. 4 (B), the light incident on each hemispherical projection 23 has the outer bottom surface 2 of the light guide 23.
Since the light is largely refracted toward the 2b side, the light that has once exited from the outer bottom surface 22b of the light guide 23 is reflected by the bottom reflection sheet 26 and is again incident into the light guide 23 from the outer bottom surface 22b. Since the complicated path of being radiated to the light emitting surface 22a is reduced, the optical energy loss is large and the device efficiency is not necessarily high.

Therefore, as shown in FIG. 3, each hemispherical projection 2
Small spherical objects 27 made of a substance having a smaller refractive index than the transparent acrylic resin plate, which is the same material as the light guide 22, are filled in each of the three.

According to this, as shown in FIG. 4A, the light incident on each hemispherical projection 23 is slightly refracted by the small spherical object 27 toward the light emitting surface 22a side, and is emitted to the light emitting surface 22a side. Therefore, the light energy loss is small and the efficiency of the device can be improved.

It should be noted that the LCD panel 16 shown in FIG. 1 is replaced with a display board such as an evacuation guidance light or a signboard having a required display by characters or figures to form a thin evacuation guidance light or a light guide plate type signboard. You may comprise.

[0035]

As described above, according to the present invention, at least the electrodeless discharge lamp which is a source of electromagnetic radiation noise, the light guide, and the lighting circuit are housed in one case.
For example, by forming the entire case with a conductor and grounding it, electromagnetic wave radiation noise can be easily shielded, and the overall size of the device can be reduced.
Further, since the light guide body is shielded by the translucent electromagnetic shield material, the shield effect can be further enhanced without lowering the instrument efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a lighting device according to the present invention.

FIG. 2 is a perspective view of a main part of another embodiment of the present invention.

FIG. 3 is a main part configuration diagram of a lighting device according to still another embodiment of the present invention.

4A is an enlarged view of a main part for explaining the operation of the embodiment shown in FIG. 3, and FIG. 4B is an explanatory view of the operation of the conventional example.

FIG. 5 is a perspective view of a part of a conventional lighting device.

[Explanation of symbols]

 11 Lighting Device 12 Case 12a Receiving Concave 12b Reflective Surface 13 Light Guide 14 Electrode Discharge Lamp 15 Lighting Circuit 16 LCD Panel 17 Metal Mesh 18 Heat Dissipation Step Groove 23 Hemispherical Protrusion 26 Bottom Reflective Sheet 27 Small Globe

Claims (6)

[Claims] 1. An electromagnetically shieldable case including at least an electrodeless discharge lamp, a lighting circuit for lighting the lamp at a high frequency, and a light guide body that receives light from the lamp and emits light in a plane. An illumination device characterized by being housed inside. 2. The lighting device according to claim 1, wherein the light guide body is shielded by a translucent electromagnetic shield material. 3. The lighting device according to claim 1, wherein the case is made of a conductor and is grounded. 4. A backlight which is configured to illuminate an object to be illuminated from the back side by the illumination device according to any one of claims 1 to 3. 5. A liquid crystal display device, wherein the illuminated object is a liquid crystal display panel. 6. The liquid crystal display device according to claim 4, wherein the illuminated body is an evacuation guidance display plate or a display plate such as a signboard.