JPH09171354A - Electromagnetic wave leakage prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid to hinder the ventilation between a PDP(Plasma Display Panel) and a circuit substrate by a electromagnetic wave shielding plate provided outside a flexible substrate connecting the PDP and the circuit substrate. SOLUTION: An aluminum board 12 is fixed on the back of PDP 11 with a double-sided adhesive tape, etc., and is mounted on a circuit substrate 1 with a fixing boss 13, being, further, mounted on the back of the housing with a fixing boss 4, connecting conductor in the periphery part of the circuit board to an electrode led to the outer peripheral part of the PDP on the flexible substrate 14, to drive the PDP 11 by a signal from the circuit substrate 1. The connecting parts of the flexible substrate 14 are abutted on the conductive part of the PDP 11 or that of the circuit substrate 1, and are clamped by spring clips 2 via retaining tools 15. Electromagnetic waves are shielded from the flexible substrate 14 by holding both outside of the PDP 11 and the spring clips 2 of the circuit substrate with both arm parts of a U-shaped electromagnetic wave shielding plate 3. Ventilation between the PDP 11 and the circuit substrate 1 is made not to be hindered, by providing the electromagnetic shielding plate 3 with ventilation holes (mesh or many holes) on the back.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave leakage prevention device for a plasma display panel (PDP), and more particularly to an electromagnetic wave shielding plate provided for shielding electromagnetic waves emitted from a flexible substrate connecting a PDP and a circuit board.

[0002]

2. Description of the Related Art Since a PDP has a smaller depth than a cathode ray tube having the same screen size, the depth of the device can be greatly reduced by mounting a circuit board on which a PDP control circuit and the like are mounted on the back surface of the PDP. However, circuit components that generate a large amount of heat are mounted on the circuit board, and the PDP itself also generates heat due to plasma discharge. The PDP has a problem that the color of a display image is discolored when the temperature rises above a prescribed level, and the rise in the temperature of the circuit board causes a decrease in reliability of circuit components. Therefore, a fan (such as a fan)
Is provided to force ventilation between the PDP and the circuit board,
The temperature of the PDP and the circuit board are prevented from rising. By the way, the PDP displays an image by the signal supplied from the circuit board on the back side as described above, and the signal line (flexible from the circuit board to the electrode led to the outer peripheral portion of the PDP for supplying this signal (flexible). It is necessary to arrange a substrate), and this flexible substrate also obstructs ventilation. Further, a high-level high-frequency current for causing the PDP to emit light flows through this signal line, and the high-frequency current radiates an electromagnetic wave, and when the leakage level of the electromagnetic wave exceeds a regulated value particularly when used in an information processing device or the like. There is.
Therefore, an electromagnetic wave blocking plate (contact strip) is attached to the outside of the flexible substrate, and the electromagnetic wave blocking plate further hinders ventilation, which causes a rise in the temperature of the PDP.

[0003]

SUMMARY OF THE INVENTION In view of the above, the present invention has an electromagnetic wave shielding plate provided on the outer periphery of a flexible substrate that connects a PDP and a circuit board, and does not prevent ventilation between the PDP and the circuit board. It is to prevent the leakage of electromagnetic waves.

[0004]

In order to solve the above-mentioned problems, the present invention arranges a circuit board on which a PDP drive circuit is mounted on the back surface of a PDP at a predetermined interval and leads to the outer peripheral portion of the PDP. In the one in which the electrode and the conductor led to the outer peripheral portion of the circuit board are connected by a plurality of flexible boards, a U-shape is formed on the outside of the flexible board, a ventilation hole is provided on the back, and both arms are provided. An electromagnetic wave leakage prevention device is provided in which an electromagnetic shield plate is provided so as to sandwich the outer surfaces of the PDP and the circuit board, and the electromagnetic shield plate is connected to the ground of the circuit board or the like.

[0005]

With the above construction, in the electromagnetic wave leakage prevention device according to the present invention, the electromagnetic wave generated by the high-frequency current flowing through the flexible substrate is shielded by the electromagnetic wave shielding plate disposed outside the flexible substrate, The amount of leakage is reduced. Ventilation holes are formed in the electromagnetic wave shielding plate, and air is allowed to flow between the PDP and the circuit board by the ventilation holes to suppress the temperature rise of the PDP and the circuit board.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an electromagnetic wave leakage prevention device according to the present invention. FIG. 1 is a schematic view of an embodiment of an electromagnetic wave leakage prevention device according to the present invention, and FIG. 2 is a sectional view of a main part.

In FIG. 1, 1 is a circuit board, 2 is a spring clip,
3 is an electromagnetic wave shielding plate (contact strip), 4 is a boss metal fitting, 5 is a tab for grounding the electromagnetic shielding plate 3,
In FIG. 2, 11 is a PDP, 12 is an aluminum plate adhered to the back surface of the PDP 11 by a double-sided adhesive tape, 13 is a boss metal fitting for fixing the PDP 11 and the aluminum plate 12 and the circuit board 1, and 14 is the circuit board 1. A flexible substrate for connecting the PDP 11 to the PDP 11, a pressing member 15 for closely contacting the connection portion of the flexible substrate 14 with the circuit board 1 or the conductor portion of the PDP 11, and 16 a folded portion at the tip of the spring clip 3.

As shown in FIG. 2, the back surface of the PDP 11 is fixed to the aluminum plate 12 with a double-sided adhesive tape or the like, the aluminum plate 12 is attached to the circuit board 1 by the boss metal fittings 13, and the back surface or the like is attached to the housing by the boss metal fittings 4. Install on. The boss metal fitting 13 and the boss metal fitting 4 are used not only for fixing the PDP 11 and the circuit board but also for radiating heat. The boss metal fitting 13 and the boss metal fitting 4 are made of a metal having good thermal conductivity, such as copper or brass.
The heat conducted from 11 to the aluminum plate 12 or the heat generated in the circuit board 1 is conducted to the housing made of metal and radiated from the surface of the housing.

The PDP 11 connects the electrodes led to the outer periphery to the circuit board 1 via the flexible board 14 and displays an image by a signal supplied from the circuit board 1. The flexible substrate 14 is formed by arranging conductors for connecting the PDP and the circuit board in a stripe shape. A pulsed high frequency current flows through these conductors, and electromagnetic waves are generated by the high frequency current. In order to reduce the leakage level of this electromagnetic wave, an electromagnetic wave shielding plate (contact strip) 3 is attached so as to cover the flexible substrate 14.

Flexible substrate 14 and electromagnetic wave shielding plate 3
The mounting state of the same is as shown in FIG. That is, the connection portions at both ends of the flexible substrate 14 are brought into contact with the electrodes of the PDP 11 and the terminal portions of the circuit board 1, respectively, and the pressing member 15 is placed on the contact portions, and the spring clips 2 are sandwiched between the PDP 11 and the circuit board 1. Fix it. Although not shown in FIG. 1, these flexible boards 14 are provided under the spring clip 2.
And there is a retainer 15.

As shown in FIG. 2, the tip of the spring clip 2
16 is curled and the tip of the electromagnetic wave shielding plate is likewise folded back to have a thickness, and this portion is inserted into the curled portion of the spring clip 2 so that the electromagnetic wave shielding plate 3 does not fall off. Although FIG. 2 shows an example in which the curl is formed on the front side (downward in the figure) of the PDP 11 of the spring clip 2 and the electromagnetic wave shielding plate 3, it is not possible to form a protrusion on the front side of the PDP 11. There is a case where it is not preferable because a space is required between the front surface portion and the front surface portion. In such a case, curl is not formed on the front surface side of the PDP 11, and the PDP 11 is fixed by using an adhesive tape or the like.

On the back surface of the electromagnetic wave shielding plate 3 (on the left side of FIG. 2),
Ventilation holes are formed as shown in FIG. That is, FIG.
(A) is an example in which the back surface is formed in a mesh shape, and (B) is an example in which a large number of small holes are formed. Alternatively, as shown in (c), small holes are provided in the gaps between the flexible substrates 2 (corresponding to the gaps between the spring clips 2 in FIG. 1), or a mesh is formed in this portion. The mesh pitch or the diameter of the small holes is set in consideration of the wavelength of the electromagnetic wave to be shielded. Then, the tab 5 is attached to the circuit board 1.
And the like, so that the voltage generated in the electromagnetic wave shielding plate 3 is grounded.

Thus, a fan (blower fan, not shown)
The air between the circuit board 1 and the PDP 11 is sucked through the ventilation holes of the electromagnetic wave shielding plate 3 by the rotation of the circuit board 1 and the PDP 11.
Prevents the temperature rise of DP11.

[0014]

As described above, according to the electromagnetic wave leakage prevention device of the present invention, since the ventilation hole is provided in the electromagnetic wave shielding plate so as not to interfere with the shielding of the electromagnetic wave, the electromagnetic wave generated in the flexible substrate is generated. Can be shut off in the same manner as in the related art, and the ventilation air passage between the PDP and the circuit board is secured, so that the temperature rise of the PDP and the circuit board can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of an electromagnetic wave leakage prevention device according to the present invention.

FIG. 2 is a sectional view of an essential part of an embodiment of an electromagnetic wave leakage prevention device according to the present invention.

FIG. 3 is a partial view of a back portion of the electromagnetic wave shielding plate.

[Explanation of symbols]

 1 circuit board 2 spring clip 3 electromagnetic wave shielding plate 4 mounting boss 11 PDP 12 aluminum plate 14 flexible substrate 15 retainer

Claims (6)

[Claims] 1. A circuit board on which a driving circuit for the plasma display panel is mounted is arranged on the back surface of the plasma display panel with a required space, and the electrodes led to the outer circumference of the plasma display panel and the outer circumference of the circuit board. A plurality of flexible boards connected to the conductor led out to, the outside of the flexible board is U-shaped, ventilation holes are provided on the back, and the outer surface of the plasma display panel and the circuit board is provided on both arms. An electromagnetic wave leakage prevention device provided with an electromagnetic shielding plate for sandwiching the electromagnetic shielding plate and connecting the electromagnetic shielding plate to the ground of the circuit board or the like. 2. The electromagnetic wave leakage prevention device according to claim 1, wherein the electromagnetic wave shielding plate has a back portion formed in a mesh shape. 3. The electromagnetic wave leakage prevention device according to claim 1, wherein the electromagnetic wave shielding plate has a large number of holes formed in its back. 4. The electromagnetic wave leakage prevention device according to claim 1, wherein the electromagnetic wave shielding plate is formed by forming a mesh-like portion at a portion facing the gap between the flexible substrates or by forming a large number of holes. 5. A flexible printed circuit board, a plasma display panel or a circuit board, wherein each connection portion of the flexible printed circuit board is fixed by a spring clip, and each spring clip is held by both arms of the electromagnetic wave shielding plate. Item 2,
The electromagnetic wave leakage prevention device according to claim 3 or 4. 6. The electromagnetic wave leakage prevention device according to claim 5, wherein the tip of the spring clip is bent outward so as to be folded back, and the tip of the electromagnetic wave shielding plate is inserted into the folded portion of the spring clip and held. .