JPH09232785A - Electromagnetic-wave shield device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a metal plate for shielding electromagnetic waves, which are radiated from flat cables which connect the drive circuit block of a liquid crystal projector with a liquid crystal panel, at low cost. SOLUTION: A metal sheet 7 is formed by punching holes 13 and 16 and projected parts 14 in an aluminium thin film or the like by a metal mold. The holes 13 in one side of the sheet 7 are inserted in bosses 12 on a color separation optical system chassis 2, a drive circuit block 5 is put on the bosses 12, the points of flat cables 6 led out from a liquid crystal panel are inserted in openings 15 formed in a shield case 11 and the cables 6 are connected with a connector. The other side of the sheet 7 is curved, the projected parts 14 are inserted in the openings 15 formed in the case 11 in such a way that they are superposed on the cables 6, the small holes 16 formed in the sheet 7 are superposed on mounting holes 18 formed in the block 5 and the case 11 is clamped on the bosses by screws 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shield device, and more particularly to an electromagnetic wave shield device for shielding an electromagnetic wave emitted from a cable for supplying a signal or the like to a liquid crystal panel of a liquid crystal projector device.

[0002]

2. Description of the Related Art In a front projection type (reflection type) liquid crystal projector device, light from a white light source is separated into red, green and blue colors by a dichroic mirror and condensed by a condenser lens to form a liquid crystal panel for each color. The light emitted from the liquid crystal panel is combined by the dichroic mirror and enlarged and projected on the screen through the projection lens. The liquid crystal panel is driven by a signal from a drive circuit block attached to the optical chassis, and the drive circuit block and the liquid crystal panel are connected by a flat cable in which a plurality of signal lines are arranged in parallel. Since a high-frequency signal current for driving the liquid crystal panel flows through the flat cable, electromagnetic waves generated by the signal current may be radiated from the flat cable and exceed the regulation value of the leakage level of electromagnetic waves. Therefore, it is necessary to shield the outside of the flat cable with a metal plate bent into an appropriate shape to reduce the leakage level of electromagnetic waves.

[0003]

As described above, the electromagnetic wave generated by the signal current of the flat cable can be shielded by covering the flat cable with a metal plate. However, the metal plate is removed by a mold and then the mold is used. Since it is bent, the cost increases. In view of such a point, the present invention is to reduce the cost of the electromagnetic wave shielding device by bending the metal sheet to cover the flat cable, eliminating the need for a mold for bending the metal plate.

[0004]

In order to solve the above-mentioned problems, the present invention solves the above problems by separating a light from a white light source into red, green and blue colors by a dichroic mirror, and a video signal for each color. Driven by, the liquid crystal panel that emits light of the corresponding image when illuminated by each color of light from the color separation optical system, and the color combining optical system that combines the light from the liquid crystal panel with the dichroic mirror etc. inside the metal box The drive circuit block for driving the liquid crystal panel is attached to the optical chassis that is installed in the drive circuit block and the liquid crystal panel is connected with a flat cable, and the drive circuit block is a shield case with an opening formed in the flat cable connection part. Cover and connect one side of the elastic metal sheet to the ground of the optical chassis, bend the other side, and insert the tip into the opening of the shield case. Was covered without gaps flat cable, there is provided an electromagnetic wave shielding apparatus adapted to shield radiation of electromagnetic waves generated by the current of the flat cable.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the electromagnetic wave shielding device of the present invention, light emitted from a white light source is separated into each color of red, green and blue by a dichroic mirror of a color separation optical system, and is driven by a video signal for each color. A drive circuit for illuminating the panel and installing an optical chassis configured to combine the light from the liquid crystal panel with the dichroic mirror of the color combining optical system inside the metal box and drive the liquid crystal panel on the outer surface of the box Attach the block, connect the drive circuit block and the liquid crystal panel with a flat cable, cover the drive circuit block with a shield case that has an opening in the flat cable connection part, and connect one side of the elastic metal sheet to the ground of the optical chassis. Connect it, form the tip of the other side into a convex shape with a width corresponding to the opening of the shield case, bend the metal sheet and seal the convex part. It was inserted into the opening of the Dokesu covers without gaps flat cable shields the radiation of electromagnetic waves generated by the current of the flat cable.

[0006]

Embodiments of the electromagnetic wave shielding device according to the present invention will be described below in detail with reference to the drawings. 1 is a perspective view showing an outline of an embodiment of an electromagnetic wave shielding device according to the present invention, FIG. 2 is an exploded perspective view of a main part, and FIG. 3 is a side sectional view of the main part.

In FIG. 1, reference numeral 1 denotes a light source section which emits white light by using a metal halide lamp or the like as the light source. Reference numeral 2 is a chassis of a color separation optical system, in which a dichroic mirror or the like is provided, and white light from the light source unit 1 is separated into respective colors of red, green and blue, and a liquid crystal panel 3 for each color is respectively passed through a condenser lens. Irradiate. A color combining optical system chassis 4 has a dichroic mirror or the like therein and combines the image lights from the three liquid crystal panels 3 and magnifies and projects it on a screen through a projection lens. A drive circuit block 5 performs signal processing for driving the three liquid crystal panels 3 and outputs signals to each liquid crystal panel 3 via a flat cable 6 in which a plurality of signal lines are arranged in parallel. Reference numeral 7 denotes a metal sheet, which shields the electromagnetic waves emitted from the flat cable 6 from leaking to the outside.

FIG. 2 is an exploded perspective view of essential parts for explaining the attachment of the metal sheet 7 and the like. The metal sheet 7 is a metal sheet having elasticity, for example, a thin plate of aluminum, copper or copper alloy, and is shown in a U-shaped curved shape in the figure, but a boss insertion hole 13 is formed on one side of the flat plate. Then
The other side end is cut into a convex shape, and the small holes 16 for screwing are formed on both sides, so that it can be easily bent.
Reference numeral 11 is a boss for mounting the drive circuit block 5 provided on the upper surface of the color separation optical system chassis 5 and the like.

To mount the metal sheet 7, first, the boss insertion hole 13 is inserted into the boss 12, then the drive circuit block 5 is placed on the boss 12, and the connecting portion (not shown) at the tip of the flat cable 6 is attached. It is inserted into the opening 15 of the shield case 11 and connected to the internal connector part. Then, the other side of the metal sheet 7 is curved, and the convex portion 14 is inserted into the opening 15 of the shield case 11 so as to overlap the flat cable 6, and the small hole 16 of the metal sheet and the mounting hole 18 of the drive circuit block 5 are inserted. Tighten to the boss 12 through the screw 17 on.

As a result, the flat cable 6 is connected to the drive circuit block 5 by inserting the convex portion 14 of the metal sheet 7 into the opening 15 of the shield case 11 as shown in the side cross-sectional view of FIG. The entire surface including the metal sheet 7 will be covered with bosses on both sides of the curved side.
The metal sheet 7 shields the electromagnetic wave radiated from the flat cable 6 because it is securely connected to the ground because it is fastened to the screw 12 with the screw 17.

Further, the metal sheet 7 is made of a synthetic resin sheet, for example, PET (polyethylene terephthalate) or the like on one side of which aluminum or the like is vapor-deposited (metallized), or thin plate-shaped aluminum, copper, copper alloy or the like. A synthetic resin sheet may be attached to one surface, and the synthetic resin side may be bent inward with the synthetic resin side facing inward. This prevents the circuit component from coming into contact with the metal sheet 7 and being grounded when the circuit component in the drive circuit block 5 and the insertion portion of the metal sheet come close to each other, and at the same time, the metal sheet 7 is prevented. The elasticity of is increased, so that it can be prevented from being deformed by a slight pressing or the like. 2 and 3 show the portion where the drive circuit block 5 is attached to the color separation optical system chassis 2, the drive circuit block 5
Is actually a size that straddles the color synthesizing optical system chassis 4, and the color synthesizing optical system chassis 4 is also provided with a boss on the upper surface and is attached by a screw or the like.

[0012]

As described above, according to the electromagnetic wave shielding device of the present invention, the flat cable connecting the liquid crystal panel and the drive circuit block of the liquid crystal panel has the elastic metal sheet, for example, a thin plate of aluminum or the like. Or, since a sheet of synthetic resin with aluminum vapor deposited is bent to cover it, the electromagnetic waves generated by the signal current of the flat cable are shielded by the metal sheet, which may reduce the leakage level to the outside. In addition, the mold for producing the metal sheet need only punch out the outer shape and the small holes, which can reduce the mold cost and contribute to cost reduction.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an embodiment of an electromagnetic wave shielding device according to the present invention.

FIG. 2 is an exploded perspective view of an essential part for explaining attachment of a metal sheet of the electromagnetic wave shielding device according to the present invention.

FIG. 3 is a side sectional view of an essential part of an electromagnetic wave shielding device according to the present invention.

[Explanation of symbols]

 2-color separation optical system chassis 3 Liquid crystal panel 4 Color composition optical system chassis 5 Drive circuit block 6 Flat cable 7 Metal sheet 11 Shield case 12 Boss 13 Boss insertion hole 14 Convex portion 15 Shield case opening 16 Small hole 17 Screw

Claims (6)

[Claims] 1. A color separation optical system for separating light from a white light source into light of each color of red, green and blue through a dichroic mirror and each color from the color separation optical system driven by a video signal for each color. Liquid crystal panel that emits light of the corresponding image when illuminated with the light of, and a color combining optical system that combines the light from the liquid crystal panel via a dichroic mirror, etc. A drive circuit block for driving the panel is attached, and the drive circuit block and the liquid crystal panel are connected by a flat cable. One side of the elastic metal sheet is connected to the earth of the optical chassis, and the other side of the metal sheet is connected. Electromagnetic shielding in which the side is curved to cover the flat cable, and the radiation of electromagnetic waves generated by the current in the flat cable is shielded by a metal sheet. apparatus. 2. The drive circuit block covers a flat cable connection portion with a shield case having an opening, and the other side of the metal sheet is inserted into the opening portion of the shield case so as to overlap the flat cable, and is flattened with the metal sheet. The electromagnetic wave shielding device according to claim 1, wherein the electromagnetic wave shielding device covers the cable. 3. The method according to claim 2, wherein the other end of the metal sheet is formed in a convex shape having a width corresponding to the opening of the shield case, and the convex portion is inserted into the opening of the shield case. Electromagnetic wave shielding device. 4. The drive circuit block is attached to a plurality of bosses provided on the outer surface of the optical chassis by screwing, and a hole through which the boss is inserted is formed in one side of the metal sheet, and the other side is formed. A hole for screwing to the boss is bored, the insertion hole of the metal sheet is fitted into the boss, the other side is bent, and the screw is attached to the boss together with the drive circuit block by the screwing hole. The electromagnetic wave shielding device according to claim 1, claim 2, or claim 3. 5. The electromagnetic wave shielding device according to claim 1, 2, 3, or 4, wherein the metal sheet is formed of a thin aluminum plate. 6. The metal sheet is formed by vapor-depositing aluminum on one surface of a synthetic resin sheet, and is bent so that the synthetic resin side is an inner side, and is attached to an electric part of a drive circuit at a portion inserted into the shield case. The electromagnetic wave shielding device according to claim 2, 3 or 4, which is configured to prevent contact of the metal part of the.