JP4759942B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a grounding structure of a liquid crystal control circuit board.

In a display device such as a liquid crystal display device, a circuit board is often covered with a metal cover for electromagnetic wave shielding. In that case, the circuit board is grounded to the metal cover. As such a technique, for example, a technique disclosed in Japanese Patent Laid-Open No. 2001-75077 “Liquid Crystal Display Device” (Patent Document 1) can be cited. Patent Document 1 discloses a technique in which an elastic pressing portion is formed on a metal casing, and the elastic pressing portion is pressed against a circuit board to ground the circuit board.
JP 2001-75077 A (page 2-3, FIG. 1-11)

  However, the conventional technique has the following problems.

  In other words, the elastic pressing part is integrated with the housing, but it is made of a material with excellent rigidity such as carbon steel or stainless steel rather than a material rich in spring biasing force, so it is used in an environment with a lot of vibration. In such a case, there is a problem that the contact pressure in the pressed state is not constant, and the contact pressure becomes unstable.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display device capable of maintaining contact stability between a casing and a liquid crystal control circuit board even under a use environment with a lot of vibration.

In order to achieve the above object, a liquid crystal display device according to the present invention includes a liquid crystal control circuit board having a ground electrode portion exposed on a surface thereof, and a metal plate that covers the liquid crystal control circuit board and constitutes a casing of a liquid crystal module. A liquid crystal display device including a housing structure, wherein the housing structure body is provided with a piece including a screw hole for fixing the screw to the liquid crystal control circuit board side, and corresponding to the screw hole. A ground terminal piece that is in contact with the ground electrode portion of the liquid crystal control circuit board through a conductive elastic block, and is formed by pressing, and the screw hole is configured to reduce an elastic force of the conductive elastic block. The piece provided with the screw hole is arranged in the proximity position to be urged, and has the elastic force of itself, and the elastic force acting between the ground electrode portion and the ground terminal piece reacts. The liquid crystal so as not to lift Characterized in that it is screwing externally fixed between the control circuit board side.

That is, according to the above-described invention, the basic displacement of the ground terminal piece is reduced, and the ground terminal piece can be efficiently pressed into contact with the ground electrode portion. The ground terminal piece may be formed like a cantilever so-called leaf spring, or may be formed with the roots on both sides and the center portion being depressed. This depression may be a trapezoid with a flat central portion or an arc without a flat portion. Further, since the casing and the ground terminal piece are integrally formed by pressing (punching / bending), it is not necessary to separately attach the ground terminal piece, and the production efficiency can be improved. Needless to say, it is assumed that the screw receiving portion and the ground electrode portion are in corresponding positions.

Moreover, the liquid crystal display device of the present invention is characterized in that a piece of the casing structure body having the screw holes is formed to be recessed from the casing configuration surface toward the liquid crystal control circuit board.

That is, the invention according to the above efficiently suppresses the floating around the screw hole, and as a result, the ground terminal piece can be efficiently pressed against the ground electrode portion. Further, it is possible to eliminate the screw head from protruding from the housing.

The liquid crystal display device is characterized in that the ground terminal piece is formed to be recessed from the housing constituting surface to the liquid crystal control circuit board side.

That is, the invention according to the above can efficiently press-contact the ground terminal piece to the ground electrode portion without forming a convex portion on the housing.

In the above liquid crystal display device, characterized by being formed together also convex in the vicinity of ground terminal pieces housing structure surface.

That is, the invention according to the above reduces the deflection of the casing and reduces the fundamental displacement of the ground terminal piece so that the ground terminal piece can be efficiently pressed against the ground electrode portion.

In the above liquid crystal display device, wherein the sandwiched conductive elastic block between the ground electrode unit grounding terminal piece.

That is, the invention according to the above absorbs vibration by the conductive elastic block and realizes stable grounding. In addition, as the conductive elastic block, for example, a core material made of a foam and a conductive sheet wound around can be used.

The liquid crystal display device is characterized in that a ground electrode portion is disposed in the immediate vicinity of the electrical connector formed on the liquid crystal control circuit board.

That is, in the invention according to the above , since the immediate vicinity of the electrical connector is grounded, it is possible to efficiently remove noise and to provide a high-quality liquid crystal display. The electrical connector here refers to a connector for connecting a flexible wiring board that transmits various signals to the liquid crystal panel. Further, the term “nearest” means a position as close as possible in design, and it is preferable that there is substantially no other circuit.

  According to the present invention, since the displacement of the ground terminal piece is reduced and the ground terminal piece can be efficiently pressed into contact with the ground electrode portion, the housing and the liquid crystal control circuit can be used even in an environment with a lot of vibration. Contact stability with the substrate can be maintained.

  Further, according to the present invention, the floating around the screw hole can be efficiently suppressed, and as a result, the ground terminal piece can be efficiently pressed against the ground electrode portion.

  Further, according to the present invention, it is possible to efficiently press-contact the ground terminal piece to the ground electrode portion without forming a convex portion on the housing.

  In addition, according to the present invention, the ground terminal piece can be efficiently pressed against the ground electrode portion by reducing the deflection of the housing and reducing the root displacement of the ground terminal piece. Even if it exists, the contact stability of a housing | casing and a liquid crystal control circuit board can be maintained.

  According to the present invention, the conductive elastic block absorbs vibration and realizes stable grounding.

  Further, according to the present invention, the immediate vicinity of the electrical connector is grounded, so that efficient noise removal can be performed and a high-quality liquid crystal display can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the structure of an in-vehicle liquid crystal module to which vibration is always applied in the usage environment will be described. FIG. 1 is a perspective view showing an external configuration of assembled liquid crystal modules from the back. FIG. 2 is a development view of the stacked liquid crystal module components.

  The liquid crystal module 100 forms a housing by a front frame 110 and a back cover 120, in which a liquid crystal panel 130, an upper case 140, an optical system (prism sheet 151, diffusion sheet 152, light guide plate 153, light source 160, and , The reflection plate 154), the lower case 170, and the liquid crystal control circuit board 180 are laminated.

  Both the front frame 110 and the back cover 120 are made of metal, and various holes, irregularities, and side surfaces are formed by stamping or bending a single plate. Specifically, a display window 111 for the liquid crystal panel 130 is cut out on the front frame 110 so as to form a bezel when viewed from the front.

  The back cover 120 is provided with a notch window 121 for introducing a flexible wiring board (not shown) to be inserted into the electrical connector 181 on the liquid crystal control circuit board 180. In addition, a ground terminal piece 122, which will be described later, and a ground terminal are provided. A screw hole 124 for indirectly energizing contact of the piece 122 with a substrate circuit exposed portion 182 (described later) is also provided.

  The liquid crystal panel 130 includes a liquid crystal substrate 131 in which liquid crystal is sealed between two transparent glass substrates, and a flexible wiring board 132 that sends a control signal to the liquid crystal substrate 131. Various types of liquid crystal panels 130 are controlled by a control signal from the liquid crystal control circuit substrate 180. Display information. The flexible wiring board 132 is connected to an electrical connector (not shown) on the liquid crystal control circuit board 180 so as to wrap the upper case 140, the optical system 150, and the lower case 170 from the outside.

  In the upper case 140, a plurality of claw feet 142 that mesh with the lower case 170 are integrally extended on a frame portion 141 having a width equal to or less than that of the front frame 110. The upper case 140 is made of resin mixed with a conductive filler, and is configured such that the influence of noise from the light source 160 does not reach the liquid crystal panel 130 by taking a ground. Therefore, since the upper case shields noise, it can be said to be a shield member. The method of grounding will be described later.

  The prism sheet 151, the diffusion sheet 152, the light guide plate 153, and the reflection plate 154 are configured to guide the light from the light source 160 to the liquid crystal panel 130 side efficiently and uniformly.

  The light source 160 includes a cold cathode tube 161 and a light source lead 162. The cold cathode tube 161 is disposed on the inner peripheral edge of the liquid crystal module 100, and the frame portion 141 of the upper case 140 is formed along the cold cathode tube 161. It is preferable that the width of the frame portion 141 be as narrow as possible without affecting the display quality of the liquid crystal when the ground of the upper case 140 is sufficiently grounded. Thereby, the area of the liquid crystal with respect to the housing can be increased, in other words, a compact and wide area liquid crystal display device can be provided.

  The lower case 170 serves as a pedestal for the liquid crystal control circuit board 180, and is provided with a claw 171 fitted on the claw foot 142 of the upper case 140 at a corresponding position. The lower case 170 is made of resin and is integrally molded, and the optical system 150 is tightly and stably joined together with the upper case 140 made of resin via the claw 171. Further, the lower case 170 is provided with two locking claws 172 for fixing the liquid crystal control circuit board 180 (one is not shown). Further, the lower case 170 is provided with a plurality of screw holes 173 for screwing the back cover 120, and the back cover 120 is firmly fixed to the lower case 170. Thereby, the liquid crystal module 100 is fixed in the vertical direction (direction perpendicular to the liquid crystal surface).

  The liquid crystal control circuit board 180 inputs an external signal through the electrical connector 181, processes the input signal by various circuits provided on the board, and outputs the processed signal to the liquid crystal panel 130. Since noise is likely to occur in the electrical circuit, particularly in the vicinity of the electrical connector 181, in order to maintain the liquid crystal display quality, a grounding substrate circuit exposed portion 182 is provided immediately next to the electrical connector 181, and the back cover 120 is The ground terminal piece 122 is grounded. The configuration of grounding will be described later.

  In the present embodiment, joints 112, 123, and 143 are provided between the front frame 110 and the back cover 120 so that the upper case 140 is sandwiched and fixed with screws 190. Further, the screw 190 is also attached to the joint 174 of the lower case 170. Thereby, the ground of the upper case 140 is taken and the noise of the light source 160 is shielded. Since the screw is inserted and fixed from the side, the liquid crystal module 100 is also fixed from the lateral direction and the stability against vibration is increased.

  Next, the configuration of grounding between the liquid crystal control circuit board 180 and the back cover 120 will be described. FIG. 3 is a cross-sectional view showing a state of grounding in the vicinity of the ground terminal piece 122. The grounding is performed by bringing the grounding terminal piece 122 of the back cover 120 into contact with the substrate circuit exposed portion 182 provided on the surface of the liquid crystal control circuit substrate 180 with a certain pressure with the conductive sponge 200 interposed therebetween. Here, the root of the ground terminal piece 122 is easily lifted by the reaction of the elastic force of the ground terminal piece 122. Therefore, in the liquid crystal module 100, a screw hole 124 is provided in the vicinity of the ground terminal piece 122 in parallel with the ground terminal piece 122.

  Therefore, by fixing the back cover 120 with the screw 191, the deflection and lifting of the root portion of the ground terminal piece 122 are suppressed, and the ground terminal piece 122 can be indirectly urged to maintain stable contact over a long period of time. It becomes. Note that the screw hole 124 and the ground terminal piece 122 are integrally formed by punching, so that the elastic force of the material can be used as it is. Furthermore, in any case, since the necessary screw holes are simply arranged in the vicinity of the ground terminal piece 122, it can be said that it is possible to improve the contact property easily and at low cost.

  The conductive sponge 200 is an elastic conductor having a sponge 201 inside and a conductor 202 outside. By making the inside the sponge 201, the contact property is improved, and even when the elastic force of the ground terminal piece 122 is lowered, the contact property can be maintained by the restoring force of the sponge.

  Further, as shown in the figure, the board circuit exposed portion 182 is disposed in the immediate vicinity of the electrical connector 181, and the ground terminal piece 122 and the screw hole 124 are recessed from the plane of the back cover 120 to approach the electrical connector 181. It is. Therefore, since the electrical connector 181 itself is positioned near the ground, it is possible to provide a high-quality liquid crystal display with less noise. In particular, it is preferable to place the board circuit exposed portion 182 between the electrical connector 181 and the screw hole 124, thereby improving the shielding effect as compared to positioning the screw hole 124 between the electrical connector 181 and the board circuit grounding portion 182. To do.

  It should be noted that the same effect can be obtained by integrally providing the back cover 120 with a ridge that passes near the ground terminal piece 122. FIG. 4 is a perspective view showing the external configuration of the liquid crystal module in the case of providing the ridges from the back side. By providing the mountain-shaped convex stripe 125 as shown in the figure, the back cover 120 is not bent, and the contact property can be maintained or further improved. The ridge 125 can also be processed simultaneously when the screw hole 124 and the ground terminal piece 122 are formed.

  The present invention can be applied to a ship, an aircraft, and the like that are used in an environment where there is a lot of vibration in addition to the on-vehicle use.

It is the perspective view which showed from the back the external appearance structure which assembled the liquid crystal module. It is an expanded view of the laminated | stacked liquid crystal module component. It is sectional drawing which showed the mode of grounding of the ground terminal piece vicinity. It is the perspective view which showed the external appearance structure of the liquid crystal module at the time of providing a protruding item | line from the back surface.

Explanation of symbols

100 LCD module 110 Front frame 111 Display window 112, 123, 143 Joint part 120 Rear cover 121 Notch window 122 Ground terminal piece 124 Screw hole 125 Projection line 130 Liquid crystal panel 131 Liquid crystal substrate 132 Flexible wiring board 140 Upper case 141 Frame part 142 Claw Leg 150 Optical system 151 Prism sheet 152 Diffusion sheet 153 Light guide plate 154 Reflection plate 160 Light source 161 Cold cathode tube 162 Light source lead wire 170 Lower case 171 Claw 172 Locking claw 173 Screw hole 174 Junction 180 Liquid crystal control circuit board 181 Electrical connector 182 Substrate circuit exposed portion 190, 191 Screw 200 Conductive sponge 201 Sponge 202 Conductor

Claims (4)

A liquid crystal display device comprising: a liquid crystal control circuit board having a ground electrode portion exposed on a surface; and a metal housing structure that covers the liquid crystal control circuit board and forms a housing of a liquid crystal module,
In the case structure,
A piece provided with a screw hole for fixing the screw to the liquid crystal control circuit board side;
A ground terminal piece that is provided corresponding to the screw hole and is in contact with the ground electrode portion of the liquid crystal control circuit board through a conductive elastic block;
Is formed by pressing,
The screw hole is disposed in a proximity position that urges the elastic force of the conductive elastic block, and the piece including the screw hole has its own elastic force, A liquid crystal display device characterized in that the liquid crystal display device is externally screwed and fixed to the liquid crystal control circuit board side so as not to lift due to the reaction of elastic force acting between the ground terminal piece and the ground terminal piece. . The liquid crystal display device according to claim 1, wherein a piece including the screw hole of the housing structure is formed by being recessed from the housing structure surface toward the liquid crystal control circuit board.   3. The liquid crystal display device according to claim 1, wherein the ground terminal piece is formed to be recessed toward the liquid crystal control circuit board from a housing constituting surface.   The liquid crystal display device according to any one of claims 1 to 3, wherein the ground electrode portion is disposed in the immediate vicinity of an electrical connector formed on the liquid crystal control circuit board.

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