JPH0792450A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To suppress the leakage of the electromagnetic wave of unwanted radiation and to prevent the malfunctions of other equipments, etc., by fitting a ferrite to the periphery of a display panel between a metallic case and a circuit board. CONSTITUTION:When this liquid crystal device is viewed in a plane direction, a source circuit board and a gate circuit board 5 for driving the liquid display device are fitted to tone periphery of the display panel 3, the outer peripheries of the source circuit board and the gate circuit board 5 are covered with the metallic case 2 used as the cover of a liquid crystal display device main body and further, the ferrite 1 is provided on the periphery of the display panel 3. Moreover, when the liquid crystal display device is viewed in the cross section by the line of A-A', the ferrite 1 is provided on tone periphery of the display panel 3 in such a manner that the ferrite 1 is held among the metallic case 2, the source circuit board and the gate circuit board 5. Thus, the ferrite 1 is provided on the periphery of the display panel 3 and held among the metallic case 2, the source circuit board 4 and the gate circuit board 5, to seal the display panel 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing leakage of unwanted electromagnetic waves in a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device used as a display device is used as one of information processing devices. However, the information processing devices such as the Voluntary Control Council for Radio Interference (VCCI) and the Federal Communications Commission Regulations (FCC) ) Are subject to the regulation of unwanted radiation. FIG. 5 is a schematic plan view showing a conventional liquid crystal display device, and FIG. 6 is an AA ′ of the liquid crystal display device shown in FIG.
7 is a sectional view of the liquid crystal display device shown in FIG.
8 is a cross-sectional view of the line, and FIG. 8 shows the near-field strength data of unnecessary radiation of the liquid crystal display device shown in FIG. 1 and the liquid crystal display device shown in FIG. Conventionally, the source circuit board 4 and the gate circuit board 5 around the display panel 3 of the liquid crystal display device have several tens of MHz.
The high-frequency video signal is input, and the electromagnetic wave D of the unwanted radiation is strong in order to input the video signal to the amplification circuit. Therefore, a filter is used to remove the unwanted radiation electromagnetic wave D or the amplification circuit. In order to suppress the leakage of the electromagnetic wave D of unnecessary radiation, a shield for covering the liquid crystal display device body with the metal case 2 is attached, and further high-frequency currents such as clock signal lines and video signal lines of the source circuit board 4 and the gate circuit board 5 are attached. The ground potential of the circuit board is used for the signal line through which the current flows and the upper and lower sides are multilayered to the ground potential to prevent leakage of the electromagnetic wave D of unnecessary radiation.

[0003]

However, in contrast to a liquid crystal display device which operates with a high frequency video signal of several tens of MHz, a filter is used for a signal line where electromagnetic waves of unwanted radiation are strong as in the conventional case, and the liquid crystal display device is also used. Even if you use a technique such as attaching a shield that covers the main body with a metal case and using the ground potential of the circuit board for the signal line through which the high-frequency current flows so that the top and bottom layers are multilayered to the ground potential, the source circuit board and gate circuit It is a problem to completely prevent the electromagnetic waves of unwanted radiation from the substrate from leaking from between the metal case and the display panel, which adversely affects other devices such as malfunction. When the source circuit board and the gate circuit board of the liquid crystal display device are driven at a fundamental frequency of 25 MHz, several times (25 × N) higher harmonics are emitted,
The data shown in FIG. 8 shows that the distance l between the interiors of the display panels of the conventional liquid crystal display B when the harmonic is emitted at 200 MHz (8 times the fundamental frequency) is 2 in the X direction from the lower left corner to the lower right corner.
The data of the near magnetic field intensity of unnecessary radiation measured for each cm is shown. As can be seen from the data of the near-field strength of unwanted radiation by the conventional liquid crystal display device B, it is difficult to completely prevent the leakage of electromagnetic waves of unwanted radiation. As described above, the influence of leakage of electromagnetic waves of unnecessary radiation on other devices due to the liquid crystal display device operating with a high-frequency video signal of several tens of MHz has been a problem in the past.

The present invention solves such a problem, and an object thereof is to provide a liquid crystal display device in which unnecessary radiation of electromagnetic waves does not easily leak even when a high-frequency video signal of several tens of MHz is input to the liquid crystal display device. Is to provide.

[0005]

According to a first aspect of the present invention, a circuit board for displaying the display panel is connected to the periphery of the display panel, and a liquid crystal display device main body is provided outside the circuit board. In the liquid crystal display device in which a metal case serving as a cover is attached, a ferrite is attached around the display panel between the metal case and the circuit board.

According to a second aspect of the present invention, the ferrite according to the first aspect is sandwiched between the metal case and the circuit board and mounted at four corners around the display panel. It has been done.

According to a third aspect of the present invention, the ferrite according to the first aspect is mounted between the metal case and the circuit board so as to surround the display panel. Is to be.

[0008]

Since the ferrite is mounted around the display panel between the metal case and the source circuit board and the gate circuit board around the display panel in the main body of the liquid crystal display device, the ferrite is attached to the periphery of the display panel. Since the components are absorbed and are converted into heat and emitted, leakage of electromagnetic waves of unnecessary radiation is suppressed.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic plan view showing a state in which a ferrite 1 according to the liquid crystal display device of this embodiment is mounted on a display panel 3, and FIG. 2 is a cross section taken along the line AA 'of the liquid crystal display device shown in FIG. 3 is a sectional view taken along line BB ′ of the liquid crystal display device shown in FIG. 1, and FIG. 4 is a schematic plan view showing another embodiment of the liquid crystal display device of the present invention.

When the liquid crystal display device of this embodiment is viewed from the plane, a source circuit board 4 and a gate circuit board 5 for driving the liquid crystal display device are mounted around the display panel 3, and the source circuit board is mounted. 4 and the gate circuit board 5
The outer periphery is covered with a metal case 2 which serves as a cover of the liquid crystal display device main body, and a periphery of the display panel 3 is surrounded by a ferrite 1. In addition, the liquid crystal display device is
When viewed in a cross section taken along the line A ′, the ferrite 1 is provided around the display panel 3 while being sandwiched between the metal case 2 and the source circuit board 4 and the gate circuit board 5. The same is true when the liquid crystal display device is viewed in a cross section taken along the line BB '.

The operation of the liquid crystal display device configured as described above will be described.

In this embodiment, in order to prevent the electromagnetic waves D of unnecessary radiation generated from the source circuit board 4 and the gate circuit board 5 inside the liquid crystal display device from leaking to the outside, the periphery of the display panel 3 is surrounded by the ferrite 1. The metal case 2 and the source circuit board 4 and the gate circuit board 5 are sandwiched and hermetically sealed. This ferrite 1 has a function of absorbing the magnetic component of the electromagnetic wave D of unnecessary radiation, converting it into heat, and releasing it. The source circuit board 4 and the gate circuit board 5 of the liquid crystal display device are set to 25 MHz.
When driven at the fundamental frequency of z, several times (25 × N) higher harmonics are emitted, and the data shown in FIG.
A near magnetic field of unnecessary radiation measured at intervals of 2 cm in the X direction from the lower left corner to the lower right corner of the distance l between the interiors of the display panels of the liquid crystal display device A of the present embodiment when emitted at MHz (8 times the fundamental frequency). Represents intensity data. As can be seen by comparing the data A of the liquid crystal display device of the present embodiment shown in FIG. 8 with the data B of the conventional liquid crystal display device, in the liquid crystal display device of the present embodiment, the ferrite 1 causes the magnetic component of the electromagnetic wave D of unnecessary radiation. Absorb,
Since the heat is emitted instead of heat, the electromagnetic wave D of unnecessary radiation does not leak from the liquid crystal display device body. FIG. 4 shows another embodiment. When the source circuit board 4 and the gate circuit board 5 are driven at a low frequency, the same effect can be obtained by arranging the ferrites 1 at the four corners around the display panel 3. Is obtained.

[0014]

As is apparent from the above description, according to the present invention, a circuit board for displaying the display panel is connected to the periphery of the display panel, and a metal serving as a cover of the liquid crystal display device main body is provided outside the circuit board. Since the case is mounted and the ferrite is mounted around the display panel between the metal case and the circuit board, the ferrite absorbs the magnetic component of the electromagnetic wave of unnecessary radiation, converts it into heat and emits it. As a result, the leakage of electromagnetic waves of unnecessary radiation can be suppressed. Therefore, it is possible to prevent other devices and the like from being adversely affected by the malfunction, and it is possible to sufficiently solve the problem of unnecessary radiation regulation defined by VCCI and FCC.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a liquid crystal display device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA ′ of the liquid crystal display device shown in FIG.

FIG. 3 is a cross-sectional view taken along the line BB ′ of the liquid crystal display device shown in FIG.

FIG. 4 is a schematic plan view of a liquid crystal display device showing another embodiment of the present invention.

FIG. 5 is a schematic plan view showing a conventional liquid crystal display device.

6 is a cross-sectional view taken along the line AA ′ of the liquid crystal display device shown in FIG.

7 is a cross-sectional view taken along the line BB ′ of the liquid crystal display device shown in FIG.

8 is a diagram showing data of near-field strength of unnecessary radiation in the liquid crystal display device of the liquid crystal display device shown in FIG. 1 and the liquid crystal display device of FIG.

[Explanation of symbols]

 1. Ferrite 2. Metal case 3. Display panel 4. Source circuit board 5. Gate circuit board 6. Base plate 7. Diffuser 8. Backlight case

Claims (3)

[Claims] 1. A liquid crystal display device in which a circuit board for displaying the display panel is connected to the periphery of the display panel, and a metal case serving as a cover of the liquid crystal display device body is attached to the outer periphery of the circuit board. A liquid crystal display device, wherein a ferrite is mounted around the display panel between the metal case and the circuit board. 2. The liquid crystal display device according to claim 1, wherein the ferrite is sandwiched between the metal case and the circuit board and mounted at four corners around the display panel. 3. The liquid crystal display device according to claim 1, wherein the ferrite is mounted between the metal case and the circuit board so as to surround the periphery of the display panel.