JPH11258623A - Plane display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electronic and electric equipment such as the plane display device which can effectively prevent a radio wave leakage and is free of an increase in cost for the prevention. SOLUTION: A part where an electromagnetic wave leaks such as the joint part between an electromagnetic wave shield case 3 and a printed board 2 below it is coated with electromagnetic wave shield paste 1 formed by dispersing powder of a magnetic material in a setting resin material. Or an electromagnetic wave generation part such as a cable connector and a driving IC is coated with the electromagnetic wave shield paste 1. Or the electromagnetic wave shield paste 1 further contains powder of a conductive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat display device in which electromagnetic wave leakage is prevented. It is a sealing / joining stopper for preventing electromagnetic wave leakage that can be used for this purpose, and generates electromagnetic waves such as electronic components such as ICs, wiring areas or component mounting areas on a printed circuit board, or cable connectors. Seal the part, or
The present invention relates to a curable resin material used for joining a portion where electromagnetic waves leak, such as a joint portion of an electromagnetic shield case of an electric device.

[0002]

2. Description of the Related Art In recent years, the widespread use of various types of computer equipment and information equipment and equipment equipped with various automatic control devices, and in particular, the speeding up of electric circuits due to their high performance. Therefore, countermeasures against electromagnetic wave leakage from these devices have become a major issue.

[0003] Leaked electromagnetic waves cause interference / interference (EMI, electromagnetic interference) with other electronic and electrical equipment.
erence), which can lead to operational failures and possibly malfunctions. It has also been pointed out that leaked electromagnetic waves may adversely affect the health of workers.

[0004] For this reason, there are many cases in Europe and the United States where various legal regulations are imposed on the permissible level of electromagnetic wave leakage.

As measures to prevent electromagnetic wave leakage, (1)
There are a method by designing the circuit and the circuit board, and a method of (2) providing a housing or a cover for shielding electromagnetic waves. Either of these measures may prevent leakage of the electromagnetic waves from the site where the electromagnetic waves are generated to the surroundings, and may block leakage of the electromagnetic waves from the surroundings.

As the above (1), a noise filter is incorporated in a circuit, a ground connection is strengthened, a layout of mounted components and wiring patterns is improved, and a circuit board is downsized. However, it is often difficult to reliably prevent electromagnetic wave leakage only by such a method,
The above measure (2) is important.

The above-mentioned measure (2) will be described by taking as an example a liquid crystal display device used as a lid portion of a notebook computer of a closed-open type or a stationary liquid crystal monitor.

(I) A conductive paint is applied to a plastic housing of a liquid crystal display. Alternatively, a plastic into which a powder of a conductive material such as carbon black is kneaded is used as a material of the housing.

(Ii) The electromagnetic wave shielding case is put on a specific place and screwed. For example, a portion on the driving printed circuit board where electromagnetic waves are remarkably generated, or a control unit affected by the electromagnetic waves is covered with an electromagnetic wave shielding case.

(Iii) An electromagnetic wave shielding tape composed of a metal foil and an insulating adhesive layer, or an electromagnetic wave shielding tape composed of an insulating film having a metal film deposited on an outer surface thereof and an adhesive layer, is placed on a printed circuit board for driving. It is attached to an electromagnetic wave generation site such as an electronic component mounting area or a wiring formation area (Japanese Patent Application Laid-Open Nos. Hei 6-37478 and Hei 7-333638).

[0011]

However, even if there is a small gap in the shielding casing or the like, as long as the gap exceeds the minimum interval determined by the wavelength of the electromagnetic wave, the electromagnetic wave leaks out of this gap or Will leak.

For example, in an electronic information device or the like, the difference between the coefficients of thermal expansion, the dimensional accuracy of the members and the assembly, and the like are different between the joints between the members constituting the housing and the hole between the input cable and the cable. For this reason, there is almost inevitably some gap where electromagnetic waves can leak, and it is very difficult to eliminate this gap at all. If the shield housing is doubled, it not only increases the cost but also increases the product weight.

For example, when a case to be covered with an electromagnetic wave shield is mounted on a chassis or the like, it is usually performed by screwing. However, unless a relatively large number of screws are used, the space between the case and the chassis is completely sealed. It is difficult. Performing a large number of screwing increases the cost and the product weight similarly to the above.

[0014] Even if an electromagnetic wave shielding tape is attached to an electromagnetic wave generation site, it is not easy to completely cover electronic component mounting portions having complicated shapes on a printed circuit board or a connector portion of a cable. This results in a large gap.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it has been found that an electronic / electric device such as a flat display device can effectively prevent electromagnetic wave leakage and hardly cause an increase in cost. provide.

[0016]

According to a first aspect of the present invention, there is provided a flat panel display, comprising: a display panel for displaying an image; a driving circuit for driving the display panel; and an external signal supplied to the driving circuit. In a flat display device including a connector portion and a housing for accommodating the connector portion, a power supply for the connector portion and the drive circuit portion is provided by an electromagnetic wave shielding / absorbing material in which a magnetic material powder is dispersed in a curable resin material. A system wiring area, an electronic component mounting area, or a joint of the housing is covered.

According to the above configuration, it is possible to effectively prevent the leakage of the electromagnetic wave, and the cost is hardly increased.

According to a second aspect of the present invention, the electromagnetic wave shielding / absorbing material further includes a powder of a conductive material.

According to the above configuration, electromagnetic wave leakage can be more effectively prevented.

According to a third aspect of the present invention, in the flat display device, the housing is made of a metal body for shielding electromagnetic waves.

According to a fourth aspect of the present invention, in the flat panel display device, the driving circuit section is formed of a printed circuit board, and includes a controller IC for controlling the display panel in the electronic component mounting area.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The electromagnetic wave shielding / absorbing material used in the present invention comprises a curable resin material in which a powder of a magnetic material or a conductive material is dispersed.

The magnetic material is a ferromagnetic non-conductive material, preferably ferrite. The magnetic material is contained, for example, in an amount of 30 to 90% by weight in the curable resin material.

As the conductive material, any material having affinity, dispersibility, and conductivity to the curable resin can be used. Preferred materials are aluminum and aluminum, which are generally used in conductive pastes. Silver can be mentioned.

As the curable resin, a two-pack type (a type in which a main agent and a curing agent are mixed at the time of use), which is a room temperature curable silicone resin, is preferable. But,
Depending on the application, a UV-curable one-pack type silicone resin, a thermosetting epoxy resin, a room temperature-curable or UV-curable epoxy resin, or the like is preferable. In addition to these, various curable resins used for general sealing and jointing can be used as long as they have appropriate workability, adhesiveness, durability after curing, and the like.

The resin before curing is preferably in the form of a paste which is easy to apply and hardly sags.

The cured resin may be rubbery or hard. However, in general, a rubber-like material often found in silicon-based resins is more preferable. To cover and seal the object, it is suitable if it is hard but tough, but a rubber-like material is more suitable to seal the gap between the joints of the housing and case. Many.

If necessary, a filler, a viscous resin component, a compatibilizer, etc. are added to the curable resin to improve the flow characteristics before curing and to improve the strength and adhesion of the cured resin. Is done.

The curable resin material preferably has an appropriate electric insulation for covering and sealing an IC, a wiring pattern and the like. However, for the purpose of covering and joining the joints of the housing, it is more preferable to use a material containing a powder of a conductive material and having enhanced electromagnetic wave shielding performance. In particular, if the housing is electrically conductive, the ground connection can be enhanced by including a powder of conductive material.

The case where the above-mentioned electromagnetic wave shielding / absorbing material is used in each part will be described below by taking a liquid crystal monitor for a personal computer as an example.

FIG. 1 shows that the electromagnetic shielding paste 1 is applied on a driving mounting printed circuit board 2 for driving a display panel.
A case where the coating is applied to joints between a printed circuit board 2 and an electromagnetic wave shield case 3 that covers a power supply system circuit (including input interface signal system wiring), which is a portion having a high electromagnetic wave generation density, is schematically shown. In the illustrated example, the cover-like electromagnetic wave shielding case 3 is a substantially flat rectangular parallelepiped having a downwardly open upper and lower side. Has been extended. At both ends of this mounting sill 31,
A screw hole 32 is provided, and the printed circuit board 2 is
Attached to. Thereafter, the electromagnetic wave shielding paste 1 is applied along the outer edge of the mounting white 31.

Since it is difficult to bring the mounting white 31 and the printed circuit board 2 into close contact with each other, a slight gap usually occurs in some places, but the gap is stopped by the electromagnetic wave shielding paste 1. Thereby, leakage of the electromagnetic wave is prevented.

In the example shown in FIG. 1, a material containing a powder of a conductive material can be used to strengthen the ground connection (ground) to the electromagnetic wave shielding case 3.

FIG. 2 shows a state where the controller IC 4 on the driving printed circuit board 2 is covered with the electromagnetic wave shielding paste 1.

The electromagnetic wave shielding paste 1 is sealed with the electromagnetic wave shielding paste 1 including the lead wire of the controller IC 4 and the connection between the lead wire and the printed wiring. Therefore, the gap from which the electromagnetic wave leaks is sealed. At this time, the electromagnetic wave shielding paste 1 contains a powder containing only a non-conductive magnetic material such as ferrite.

Since the shielding is performed by the electromagnetic wave shielding paste 1, even when the mounting component has a complicated shape and it is difficult to completely cover the component with the electromagnetic wave shielding film as described above, the shielding is easily performed without any gap. be able to.
Therefore, more reliable electromagnetic shielding can be performed.

FIG. 3 shows that the cable connector 5 located at the end of the driving printed circuit board 2 is connected to the electromagnetic wave shielding paste 1.
Shows a state of sealing.

The input cable 6 is connected to the driving printed circuit board 2.
The cable connector 5 comprises a plug 51 at the end of the input cable 6 and a cable socket 52 for receiving the plug.

The cable line of the input cable 5 is covered with a cable covering having an electromagnetic shielding layer, but is not provided on a plug which is a connection end. In addition, a gap is almost inevitably generated between the insertion plug 51 and the cable socket 52. If this gap is left, considerable electromagnetic waves will leak from the cable connector 4 portion.

With the method shown in FIG. 3, leakage of electromagnetic waves from the cable connector 4 can be easily and reliably prevented or suppressed.

FIG. 4 shows a state in which the joint portion 71 of the housing 7 of the liquid crystal monitor 70 that houses the driving printed board 2 and the display panel is joined by the electromagnetic shielding paste 1.

[0042] Such joint stop prevents the electromagnetic wave from leaking from a slight gap at the joint. In addition, it is possible to prevent external electromagnetic waves from leaking from the gap and causing interference or obstruction to the internal drive circuit.

[0043]

According to the present invention, there is provided an electronic / electric device such as a flat panel display device which can effectively prevent electromagnetic wave leakage and hardly causes an increase in cost.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example in which an electromagnetic wave shielding case for covering an electromagnetic wave generation portion on a driving printed circuit board with an electromagnetic wave shielding paste and a driving printed circuit board are joined.

FIG. 2 is a controller IC on a driving printed circuit board 2.
FIG. 4 is a schematic perspective view showing a state in which an electromagnetic wave shielding paste 4 is covered with an electromagnetic wave shielding paste 1.

FIG. 3 is a schematic perspective view showing a state in which a cable connector 5 located at an end of a driving printed board 2 is sealed with an electromagnetic wave shielding paste 1;

FIG. 4 is a schematic perspective view showing a state where joint portions of a housing of the liquid crystal monitor are joined by an electromagnetic shielding paste.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Electromagnetic wave shielding paste 2 Driving printed circuit board with built-in LCD monitor 3 Electromagnetic wave shielding case put on a part of driving printed circuit board 4 Controller IC on driving printed circuit board 5 Cable connector 51 Insertion plug 52 Socket 6 Input cable 7 LCD monitor Housing

Claims (4)

[Claims] 1. A display panel for displaying an image, a driving circuit for driving the display panel, a connector for supplying an external signal to the driving circuit, and a housing for accommodating these components. In the flat display device, the electromagnetic wave shielding / absorbing material in which the powder of the magnetic material is dispersed in the curable resin material allows the connector portion, the power supply wiring region or the electronic component mounting region of the drive circuit portion, or
A flat display device, wherein a joint of the housing is covered. 2. The flat display device according to claim 1, wherein the electromagnetic wave shielding / absorbing material contains a powder of a conductive material. 3. The flat display device according to claim 1, wherein the housing is made of a metal body for shielding electromagnetic waves. 4. The flat display device according to claim 1, wherein the drive circuit section is formed of a printed circuit board, and includes a controller IC for controlling the display panel in the electronic component mounting area.