JP4927679B2 - Electric equipment and circuit board cooling method - Google Patents

Description

  The present invention relates to a structure of a thin electric device typified by a liquid crystal display and the like, and a method for cooling a circuit board used in the electric device.

  In recent years, various electric devices have various forms depending on their purposes. In particular, displays (display devices) are becoming thinner in order to overcome both the problems of increasing the screen size and securing the installation location.

  A circuit board on which a transformer, a power transistor, and the like are mounted is provided in the liquid crystal display, and these generate heat during use. Further, the liquid crystal display is provided with a backlight unit as a light source adjacent to the liquid crystal panel, and this backlight unit also generates heat. Therefore, a configuration in which such heat radiation is performed efficiently is employed. In particular, when the thickness is reduced, the area of the liquid crystal panel, backlight unit, and circuit board is increased, but these are installed close to each other, so the configuration is important for efficient cooling. It becomes.

  For example, Patent Document 1 discloses a liquid crystal display device in which heat generating parts such as an inverter are concentrated on the periphery of a backlight unit and a metal having a high thermal conductivity is brought into contact with the heat generating parts in the vicinity to increase heat dissipation efficiency. Are listed. In this structure, the cooling efficiency of the heat generating component (circuit board) can be increased, and the cooling efficiency of the backlight unit can also be increased.

In addition, FIG. 2 shows a cross-sectional view of an example of a structure employed in a liquid crystal display. In the liquid crystal display 90, a flat liquid crystal panel 91 and a backlight unit 92 are stacked and installed. Further, a circuit board 94 on which a heat generating component 93 such as a transformer and a power transistor is installed is also installed in parallel therewith. In order to maintain electrical insulation between the circuit board 94 and the backlight unit 92 and the like, an insulating sheet 95 is attached to the back surface of the backlight unit 92. The above structure is housed in the housing 96. The liquid crystal display 90 is used with the direction of the arrow in FIG. In this case, the heat generated from the backlight unit 92 is radiated to the space between the insulating sheet 95 and the circuit board 93 through the insulating sheet 95. The heat radiation from the circuit board 94 is also radiated between the insulating sheet 95 and the circuit board 93, and the airflow therebetween becomes the direction of the arrow shown in FIG. As a result, the backlight unit 92 and the circuit board 93 are cooled. With this structure, heat radiation from the backlight unit 92 and the circuit board 94 can be efficiently performed. In particular, these cooling can be performed by natural convection without using a cooling fan or the like.
Japanese Patent Laid-Open No. 6-160813

  However, in general, various electronic components are mounted on a circuit board used in a liquid crystal display, and there are a large number of components that generate heat, and these connection methods (positional relationships) are determined by the circuit configuration. Therefore, as in the method described in Patent Document 1, it is difficult to have a layout in which all the heat generating components are arranged in the periphery of the backlight unit.

  In the structure shown in FIG. 2, when the thickness is reduced, the distance between the insulating sheet and the circuit board is narrowed, and it is difficult to ensure the air permeability between them. In particular, since the distance between the circuit board serving as a heat source and the backlight unit becomes narrow, it becomes difficult to cool them by cooling these gaps. That is, it is difficult to ensure sufficient cooling efficiency when the liquid crystal display is thinned.

  Therefore, it has been difficult to achieve both insulation with respect to the circuit board and high cooling efficiency in a thin electric apparatus having a circuit board that generates heat.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The electrical device of the present invention has a structure in which a circuit board on which a heat generating component is mounted and another flat plate-like component are disposed adjacent to each other, and cooling air is provided between the circuit board and the component. In the flowing electric device, the surface of the component on the side of the circuit board has a corrugated shape on the surface in which peaks and valleys are formed along a direction substantially perpendicular to a direction in which the cooling air flows. An insulating sheet is affixed, and a vent hole penetrating the circuit board is provided at a location adjacent to the heat generating component on the circuit board.
In the electric device of the present invention, the electric device is a liquid crystal display, and the component is a backlight unit.
In the electric device of the present invention, the cooling air is generated by convection, and the crests and troughs in the insulating sheet are formed along a direction substantially perpendicular to the vertical direction.
In the electric device of the present invention, the insulating sheet is made of PC (polycarbonate).
The method for cooling a circuit board according to the present invention has a structure in which a circuit board on which a heat generating component is mounted and another flat plate-like component are disposed adjacent to each other, and between the circuit board and the component. A method for cooling the circuit board in an electrical device through which cooling air flows, wherein a peak portion and a valley portion are provided on a surface of the component on the circuit board side along a direction substantially perpendicular to a direction in which the cooling air flows. An insulating sheet having a corrugated shape formed on the surface is affixed, and a vent hole penetrating the circuit board is provided at a location adjacent to the heat generating component in the circuit board.

  Since the present invention is configured as described above, in a thin electric device having a circuit board on which a heat generating component is mounted, both insulation with respect to the circuit board and high cooling efficiency can be achieved.

  Hereinafter, the best mode for carrying out the present invention will be described. Hereinafter, a liquid crystal display having the structure of the present invention will be described as an embodiment of the present invention.

  FIG. 1A is a cross-sectional view showing the structure of the liquid crystal display according to the first embodiment of the present invention. The liquid crystal display 10 is installed so that the vertical direction in FIG. 1A is the actual vertical direction. That is, FIG. 1A is a cross-sectional view of the installed liquid crystal display 10 cut in the vertical direction.

  In the liquid crystal display 10, a backlight unit 12 is provided in close contact with the back side of the liquid crystal panel 11. The liquid crystal panel 11 modulates the light emitted from the backlight unit 12 with liquid crystal and displays a color image. If the size of the liquid crystal panel is 32 type, for example, it is about 74 cm × 44 cm, and its thickness is about 2 mm. The size of the backlight unit 12 is the same as that of the liquid crystal panel, and the thickness is about 30 mm. The backlight unit 12 includes a large number of light sources such as discharge lamps, which emit light and serve as light sources for liquid crystal displays. For this reason, the backlight unit 12 also serves as a heat source.

  The circuit board 13 is configured by mounting various components on a printed board. For example, bakelite is used as the material of the printed circuit board. The mounted components include a driving LSI element, a power supply component, and the like. Among them, the circuit board 13 serves as a heat source because a heat generating component 131 such as a transformer or a power transistor is mounted. Further, in order to reduce the thickness of the liquid crystal display 10, it is necessary to narrow the distance between the circuit board 13 and the backlight unit 12, and for example, the distance is set to about 5 mm. However, since many electrical connections are provided on the surface of the circuit board 13 on the backlight unit 12 side, it is also necessary to provide electrical insulation between the circuit board 13 and the backlight unit 12. is there.

  In the liquid crystal display 10, it is necessary to deal with heat generation of both the backlight unit 12 and the circuit board 13. That is, it is necessary to increase these cooling efficiencies.

  For this reason, a corrugated insulating sheet (insulating sheet) 14 is affixed to the surface of the backlight unit 12 on the circuit board 13 side, or is formed in close contact. FIG. 1B is an external view of the corrugated insulating sheet 14 viewed from the right side in FIG. The surface of the corrugated insulating sheet 14 on the side of the circuit board 13 has a corrugated shape. In this corrugated shape, the crests 141 and the troughs 142 are formed along the horizontal direction. As the material of the insulating sheet, a material that is mechanically soft and has high insulating properties, such as PC (polycarbonate), is used. Therefore, the electrical insulation between the circuit board 13 and the backlight unit 12 is maintained by the corrugated insulating sheet 14.

  In the circuit board 13, a vent hole 132 that penetrates the circuit board 13 is formed at a location adjacent to the heat generating component 131.

  In this configuration, the effective surface area of the corrugated insulating sheet 14 is widened by the corrugated shape provided on the surface of the corrugated insulating sheet 14. Therefore, it is possible to increase the heat dissipation efficiency for dissipating heat from the backlight unit 12 on the surface of the wave-like insulating sheet 14.

  The above structure is accommodated in the housing 15. The casing 15 is configured of a material that can store these structures and can maintain sufficient mechanical strength, for example, PS (polystyrene). The housing 15 is provided with cooling housing windows 151 on the back surface and the lower portion, respectively. The cooling air is incident from the lower casing window 151 by convection, flows upward as indicated by an arrow in FIG. 1, and exits from the rear casing window 151.

  The corrugated crests 141 and troughs 142 formed in the corrugated insulating sheet 14 are formed along a direction perpendicular to the direction of the airflow, which becomes an obstacle to the airflow. Therefore, the airflow easily passes through the vent hole 132. Therefore, the heat generating component 131 adjacent to the vent hole 132 is easily cooled by the airflow. This effect is particularly noticeable when the interval between the corrugated insulating sheet 14 and the circuit board 13 is narrow. The direction in which the peak portions 141 and valley portions 142 of the wave structure are formed is only required to be a direction in which the cooling air easily passes through the vent holes 132. In the case of the structure of FIG. It does not have to be. That is, the direction in which they are formed can be a direction substantially perpendicular to the airflow.

  Therefore, with this structure, particularly when the liquid crystal display 10 is thin, the backlight unit 12 and the circuit board 13 (the heat generating component 131) can be efficiently cooled. Alternatively, in the method of cooling the circuit board used in the liquid crystal display 10, the cooling efficiency of the circuit board 13 is increased by using the corrugated insulating sheet 14 having the above-described configuration and providing the circuit board 13 with the vent holes 132. ing.

  In this structure, a circuit board 13 having a corrugated insulating sheet 14 having a corrugated structure on the surface and a vent hole 132 is used. As described above, for example, PC is used as the material of the corrugated insulating sheet 14. The surface of the corrugated insulating sheet 14 can be easily realized by using a mold having this shape during sheet molding. Further, the main body of the circuit board 13 is made of, for example, bakelite, and the formation of the air vent 132 penetrating the bakelite can be easily performed by various mechanical processes. Therefore, the liquid crystal display 10 having the structure shown in FIG. 1 can be easily manufactured.

  In the thin liquid crystal display having the above-described structure, both the insulation with respect to the circuit board and the high cooling efficiency with respect to the heat-generating component mounted on the circuit board can be achieved.

  In the above embodiment, the airflow between the backlight unit and the circuit board is generated by convection. However, the present invention is not limited to this, and cooling air may be generated by a cooling fan. In this case, it is preferable to form valleys and peaks in the corrugated shape on the surface of the corrugated insulating sheet along a direction substantially perpendicular to the direction of the cooling air. As a result, the same effect can be obtained.

  Further, a circuit board on which a heat generating component is mounted is used in general electrical equipment, and it is generally required to maintain high electrical insulation with respect to the circuit board. Therefore, although the liquid crystal display has been described in the above embodiment, a similar structure can be used in a thin electric device having a circuit board on which a heat-generating component is mounted. It is possible to achieve both high cooling efficiency for the heat generating components mounted on the substrate. That is, an electric device having a structure in which a circuit board on which a heat generating component is mounted and another flat part are set adjacent to each other, and cooling air flows between the circuit board and the part. If so, it is obvious that the same effect as described above can be obtained by adopting the same structure. In this case, the corrugated insulating sheet may be attached to this flat part.

  In particular, in the above embodiment, the backlight unit, which is a component to which the corrugated insulation sheet is attached, also serves as a heat source. It is clear that the cooling efficiency for the heat generating parts can be increased.

It is sectional drawing (a) which shows the structure of the liquid crystal display used as embodiment of this invention, and the figure (b) which shows the surface shape of the corrugated insulation sheet used here. It is sectional drawing which shows an example of the structure of the conventional liquid crystal display.

Explanation of symbols

10, 90 Liquid crystal display 11, 91 Liquid crystal panel 12, 92 Backlight unit 13, 94 Circuit board 14 Corrugated insulation sheet 15, 96 Case 93, 131 Heating component 95 Insulation sheet 97, 151 Case window 141 Mountain part 142 Valley part

Claims (5)

An electric device having a structure in which a circuit board on which a heat-generating component is mounted and another flat plate-like component are disposed adjacent to each other, and cooling air flows between the circuit board and the component,
The surface on the circuit board side of the component is affixed with an insulating sheet having a corrugated shape with a ridge and a valley formed on the surface along a direction substantially perpendicular to the direction in which the cooling air flows.
An electric device characterized in that a vent hole penetrating the circuit board is provided at a location adjacent to the heat generating component in the circuit board.   The electrical device according to claim 1, wherein the electrical device is a liquid crystal display, and the component is a backlight unit.   The electric device according to claim 1, wherein the cooling air is generated by convection, and a crest and a trough in the insulating sheet are formed along a direction substantially perpendicular to a vertical direction.   The electric device according to any one of claims 1 to 3, wherein the insulating sheet is made of PC (polycarbonate). The circuit board in an electrical device having a structure in which a circuit board on which a heat generating component is mounted and another flat plate-like part are disposed adjacent to each other and cooling air flows between the circuit board and the part Cooling method,
Affixing an insulating sheet having a corrugated shape on the surface of which the crests and troughs are formed along a direction substantially perpendicular to the direction in which the cooling air flows on the surface of the circuit board in the component,
A cooling method for a circuit board, comprising: providing a vent hole penetrating the circuit board at a location adjacent to the heat generating component in the circuit board.

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