JPH06202103A - Back light unit for liquid crystal - Google Patents

Abstract

PURPOSE:To satisfactorily obtain a heat radiating effect for a fluorescent tube with a simple structure without generating the danger of high voltage leakage and to make a unit compact with high luminance by covering the electrode part of the fluorescent tube with an electrical insulator, and connecting the insulator to a heat insulating board provided on the outside of a reflector. CONSTITUTION:The electrical insulator 15 is formed with a rubber cap with superior heat conductivity, and is loaded on the electrode parts 13a, 13b which form both terminal parts of the fluorescent tube 13, and an inverter circuit 14 is connected to the electrode of the fluorescent tube 13 via the aperture part of the rubber cap 15. Furthermore, the rubber cap 15 is connected to the heat insulating board 16 provided on the outside of the reflector 12, and the heat insulating board 16 is formed with the conductive pattern 14b of the substrate 14a of the inverter circuit 14. Since the electrode parts 13a, 13b are covered with the electrical insulator 15, a high voltage part can be insulated, the high voltage leakage from occurring is prevented. Also, since the insulator 15 is connected to the heat insulating board 16, heat can be diffused from the insulator 15 to the heat insulating board 16, and also, since the heat insulating board 16 is provided on the outside of the reflector 12, heat radiation can be performed effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display backlight unit for illuminating a liquid crystal display device from the back side thereof, and more particularly to a liquid crystal display backlight unit having an improved heat dissipation structure of a fluorescent tube.

[0002]

2. Description of the Related Art Conventionally, in order to brightly display a display screen of a liquid crystal display device, a liquid crystal backlight unit for illuminating liquid crystal from its back side has been used. FIG. 5 shows an example of this type of liquid crystal backlight unit. As shown, the liquid crystal backlight unit 1 includes a fluorescent tube 2 provided on the back side of a liquid crystal display device (not shown), a circuit section 3 for turning on the fluorescent tube 2, and It is composed of a reflector 4 which reflects the light emitted from the fluorescent tube 2 to the liquid crystal. The fluorescent tube 2 has, for example, a U shape so as to illuminate the entire liquid crystal. The circuit section 3 is formed by an inverter circuit to increase the illuminance of the fluorescent tube 2 and is connected to the electrodes 5a and 5b of the fluorescent tube 2. Further, the reflection plate 4 is formed in a box shape so as to cover the fluorescent tube 2 and is provided behind the fluorescent tube 2. A copper foil sheet 4a is attached to the back surface of the reflection plate 4 as needed, as shown in FIG. As a result, unit noise generated from the fluorescent tube 2 or the like can be shielded.

By the way, the electrode portions 2a, 2 of the fluorescent tube 2 are
b has a higher temperature than other parts. Therefore, the following measures have been taken as measures against the heat radiation. First,
As shown in FIG. 5, the electrode portions 2a and 2b of the fluorescent tube 2 are
Heat sinks 6a, 6b made of sheet metal so as to contact the
Are provided respectively, and the heat of the electrode portions 2a, 2b is diffused to the heat sinks 6a, 6b to radiate heat.

Further, as shown in FIG. 6, the vicinity of the electrode portions 2a and 2b of the fluorescent tube 2 is held by a holding member 7 to increase the distance between the fluorescent tube 2 and the reflection plate 4, and Heat is radiated by open air through the opening 4a formed in the reflection plate 4 for connection with the circuit unit 3.

Further, the electrode portions 2a, 2b of the fluorescent tube 2 are
The input power was reduced in order to suppress the heat generation.

[0006]

However, the conventional liquid crystal backlight unit 1 has the following problems. That is, the heat sink 6 as shown in FIG.
In the heat dissipation structure by a and 6b, there is a problem that there is a risk of high voltage leak because the high voltage part and the heat sinks 6a and 6b are close to each other.

Further, since the heat sinks 6a and 6b made of sheet metal are brought into close contact with the fluorescent tube 2, there is a problem that capacitive coupling occurs and the startability of the fluorescent tube 2 deteriorates.

Further, in the heat dissipation structure by the holding member 7 shown in FIG. 6, since the distance between the fluorescent tube 2 and the reflection plate 4 is increased, the liquid crystal backlight unit 1 becomes large and complicated. However, there is a problem in that it is not possible to meet the demand for thinning and miniaturization (compactness).

If the input power to the fluorescent tube 2 is lowered, there is a problem that desired high brightness cannot be obtained.

In view of the above problems, an object of the present invention is to provide a simple structure without the risk of high-pressure leak, obtain a good heat dissipation effect of a fluorescent tube, and meet the demand for high brightness and compactness. It is to provide a backlight unit for liquid crystal, which is capable of

[0011]

According to the liquid crystal backlight unit of the present invention, the above object is to provide a fluorescent tube provided on the back side of a liquid crystal display device and an electrode for lighting the fluorescent tube. In a backlight unit for liquid crystal comprising a circuit portion connected to the fluorescent tube and a reflector for reflecting the light from the rear of the fluorescent tube to the liquid crystal side, at least the electrode section of the fluorescent tube is covered with an electrical insulator. This is achieved by connecting this insulator to a heat dissipation plate provided outside the reflection plate.

In the above structure, it is preferably achieved by the electric insulator having good thermal conductivity.

Further, it is preferably achieved by forming the electric insulator with a rubber cap.

Further, it is preferable that the heat radiation plate is formed by a conductive pattern of the substrate of the circuit section.

And preferably, it is achieved by forming the area of the conductive pattern to be large.

Further, it is preferable that the heat radiation plate is formed by a conductive material for shielding attached to the back surface of the reflection plate, preferably a copper foil sheet.

[0017]

According to the above construction, at least the electrode portion of the fluorescent tube is covered with the electric insulator. Therefore, the high voltage portion is insulated and there is no concern about high voltage leakage. Since this electric insulator is connected to the heat sink, heat is diffused from the insulator to the heat sink, and since the heat sink is provided outside the reflector, heat is effectively dissipated. It is something.

In particular, if the electric insulator is made of an insulator having good thermal conductivity, heat can be efficiently diffused to the heat dissipation plate.

If the electric insulator is formed of a rubber cap, it can be easily attached to the fluorescent tube.

Further, if the heat dissipation plate is formed of the conductive pattern of the circuit board of the circuit section, there is no need to provide a separate heat dissipation plate, and the structure is simplified.

If the area of this conductive pattern is made larger than usual, the heat dissipation effect is further promoted.

Further, if the heat dissipation plate is made of a conductive material for shielding attached to the back surface of the reflection plate, preferably a copper foil sheet, there is no need to provide a separate heat dissipation plate, and the structure is simplified.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The examples described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are given, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 shows a first embodiment of a liquid crystal backlight unit according to the present invention. This liquid crystal backlight unit is provided on the back side of a liquid crystal display device (not shown). . As shown, the outer shape of the liquid crystal backlight unit 11 is a box-shaped reflector plate 12.
It is formed in. In the reflector 12, a U-shaped fluorescent tube 13 is provided to illuminate the entire liquid crystal. The reflection plate 12 is arranged so that the light emitted from the fluorescent tube 13 is effectively reflected to the liquid crystal.
It is located behind. A circuit portion 14 for lighting the fluorescent tube 13 is connected to an electrode (not shown) of the fluorescent tube 13. The circuit portion 14 is formed of an inverter circuit in order to increase the illuminance of the fluorescent tube 13, and its substrate 14a is attached to the reflector 12 so as to cover the electrode side front surface thereof.

Further, as shown in FIG. 2, at least the electrode portions 13a and 13b of the fluorescent tube 13 are covered with an electric insulator 15. The electric insulator 15 has a good heat conductivity, and in this embodiment, it is formed of a rubber cap having a good heat conductivity. That is,
Rubber caps 15 having good thermal conductivity are attached to the electrode portions 13a and 13b at both ends of the fluorescent tube 13, and the inverter circuit 14 is connected to the electrodes of the fluorescent tube 13 through the openings of the rubber cap 15. ing.

Further, the rubber cap 15 is connected to a heat dissipation plate 16 provided outside the reflection plate 12.
As shown in FIG. 3, in this embodiment, the heat dissipation plate 16 is formed of the conductive pattern 14b of the substrate 14a of the inverter circuit 14. That is, FIG.
The conductive pattern 14b of this embodiment shown in FIG.
The area is larger than that of the conventional conductive pattern 14c shown in FIG. In this embodiment, the heat dissipation plate 16 is also used as the conductive pattern 14b, but it may be provided separately.

Next, the operation of the above embodiment will be described.
As described above, at least the electrode portion 1 of the fluorescent tube 13
3a is covered with a rubber cap having good thermal conductivity as the electric insulator 15. Therefore, the high-voltage portion is insulated and the risk of high-voltage leakage can be prevented, and since the electric insulator 15 is formed of the rubber cap, the fluorescent tube 13 can be prevented.
It can be attached to the body very easily.

Since the rubber cap 15 is connected to the conductive pattern 14b of the substrate 14a of the inverter circuit 14, the electrode portions 13a and 13b of the fluorescent tube 13 are connected.
The high heat can be diffused from the rubber cap 15 to the conductive pattern 14b, and since the conductive pattern 14b is provided outside the reflection plate 12, heat can be effectively dissipated. In particular, since the rubber cap 15 has good thermal conductivity, it is possible to extremely efficiently diffuse heat to the conductive pattern 14b.

In addition, as shown in FIG. 3B, if the conductive pattern 14b is formed to have a larger area than the conventional one, the heat radiation effect can be further promoted. Further, since the heat dissipation plate 16 and the conductive pattern 14b are also used, it is not necessary to separately provide the heat dissipation plate 16, so that the structure can be simplified and the liquid crystal backlight unit 11 can be made compact. Is something that can be done. Furthermore, since it is not necessary to reduce the input power to the fluorescent tube 13, a desired high brightness can be obtained.

FIG. 4 shows a second embodiment of the liquid crystal backlight unit according to the present invention. This liquid crystal backlight unit is provided on the back side of a liquid crystal display device (not shown). . In this case, in the liquid crystal backlight unit 20, a copper foil sheet 16 for shielding unit noise is attached to the back surface of the reflection plate 12 as compared with the liquid crystal backlight unit 11 shown in FIGS. 1 and 2. In addition, the rubber cap 15 has a different configuration in that it is connected to the copper foil sheet 16.

In the liquid crystal backlight unit 20 having such a structure, at least the electrode portion 13a of the fluorescent tube 13 is covered with the rubber cap as the electric insulator 15 having a good thermal conductivity. Therefore, the high-voltage portion is insulated and the risk of high-voltage leakage can be prevented, and the electric insulator 15 is formed by the rubber cap.
It can be attached to the unit 3 very easily.

Since the rubber cap 15 is connected to the copper foil sheet 16 for shielding attached to the back surface of the reflection plate 12, the electrode portion 13 of the fluorescent tube 13 is connected.
High heat of a and 13b is transferred from the rubber cap 15 to the copper foil sheet 1
6 and the copper foil sheet 16
Is provided outside the reflector 12, so that heat can be effectively radiated. In particular, the rubber cap 15
Has a good thermal conductivity, heat diffusion to the copper foil sheet 16 can be performed very efficiently.

[0033]

As described above, according to the liquid crystal backlight unit of the present invention, a good heat dissipation effect of the fluorescent tube can be obtained with a simple structure without the risk of high-pressure leakage. It is bright and compact.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of a first embodiment of a backlight unit for liquid crystal according to the present invention.

FIG. 2 is a cross-sectional view showing an electric insulator in the liquid crystal backlight unit of FIG.

FIG. 3 shows a substrate of a circuit section in the present embodiment, (a)
Is a comparative explanatory view of a conventional conductive pattern, and (b) is a comparative explanatory view of a conductive pattern of the present embodiment.

FIG. 4 is a cross-sectional view showing an electric insulator in a second embodiment of the liquid crystal backlight unit according to the present invention.

FIG. 5 is an exploded perspective view showing an example of a conventional liquid crystal backlight unit.

FIG. 6 is an exploded perspective view of another example of the liquid crystal backlight unit of FIG. 5, viewed from the back.

FIG. 7 is a main part perspective view showing another example of the conventional liquid crystal backlight unit.

[Explanation of symbols]

 11 Backlight Unit for Liquid Crystal 12 Reflector 13 Fluorescent Tube 13a Fluorescent Tube Electrode Part 15 Electrical Insulator 16 Radiator 17 Shield Copper Foil Sheet

Claims (7)

[Claims] 1. A fluorescent tube provided on the back surface side of a liquid crystal display device, a circuit portion connected to an electrode for lighting the fluorescent tube, and the light from the rear side of the fluorescent tube to the liquid crystal side. In a backlight unit for liquid crystal having a reflecting plate for reflecting, at least the electrode portion of the fluorescent tube is covered with an electric insulator, and the insulator is connected to a heat radiating plate provided outside the reflecting plate. The backlight unit for LCD. 2. The backlight unit for liquid crystal according to claim 1, wherein the electrical insulator has good thermal conductivity. 3. The liquid crystal backlight unit according to claim 1, wherein the electrical insulator is formed of a rubber cap. 4. The backlight unit for liquid crystal according to claim 1, wherein the heat dissipation plate is formed of a conductive pattern on a substrate of the circuit section. 5. The backlight unit for liquid crystal according to claim 4, wherein the conductive pattern has a large area. 6. The liquid crystal display device according to claim 1, wherein the heat dissipation plate is made of a conductive material for a shield attached to the back surface of the reflection plate. Backlight unit. 7. The backlight unit for liquid crystal according to claim 6, wherein the conductive material is a copper foil sheet.