JP3036913B2 - Device to suppress electric field radiation from flat display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for suppressing electric field radiation from a flat display device such as a liquid crystal display device and a plasma display device.

[0002]

2. Description of the Related Art A display terminal device (V
Electric field radiation in DT), particularly electric field radiation of 5 Hz to 400 kHz, has a problem because it has a bad influence on the human body.

[0003] Compared to a display device using a cathode ray tube, the liquid crystal display device is said to emit less electric field, but is radiated from a backlight, an inverter, an AC driven display panel, etc. included in the liquid crystal display device. Electric field is a problem.

[0004] The radiation of such an electric field can be effectively shielded in the front surface of the display panel, that is, in a region other than the display surface by a shielding material made of a metal plate or the like.

[0005]

However, on the front surface of the display panel, an image must be displayed so that it can be visually recognized, so that a shield made of a metal plate or the like cannot be simply applied.

For this reason, it is conceivable to provide a transparent conductive film or a conductive filter on the front surface of the display panel. However, high cost is required to adopt these techniques, and the cost is high. The shielding effect is not enough.

[0007] The above-mentioned problem is encountered in flat display devices in general, other than liquid crystal display devices, as long as they are AC driven, including plasma display devices.

Therefore, an object of the present invention is to provide a device capable of effectively suppressing an electric field radiated from a display surface of a flat display device.

[0009]

The invention according to claim 1 is
A display panel having a common electrode, wherein the display panel has a common electrode.
Flat display device where alternating voltage is applied to conductive electrodes
Chassis frame that holds the display panel
And an AC-driven drive placed on the chassis frame
The moving electrode and the electric field radiated from the display panel have opposite polarities.
Means for applying a voltage to the drive electrodes.

[0010] The invention according to claim 2 has a common electrode.
A display panel, wherein an alternating voltage is applied to a common electrode of the display panel.
In a flat display device to which
Front panel arranged to cover the periphery of the panel
And a drive that is placed on the front panel and is AC driven
The electrodes have an opposite polarity to the electric field radiated from the display panel.
Means for applying pressure to the drive electrode.

In the invention according to claim 3, claim 1 or
The means for applying the voltage of the opposite polarity of 2 to the drive electrode is
Means for adjusting the amplitude of the voltage of
You.

In the invention according to claim 4, claim 1 or
The means for applying a voltage of the opposite polarity of 2 to the electrode is
It is characterized by including means for inverting the phase.

[0013]

In the present invention, the electric field radiated from the display panel of the flat display device is canceled by the opposite polarity voltage applied to the electrodes.

[0014]

Therefore, according to the present invention, the electric field radiated from the display panel is effectively suppressed. The effect of this suppression is most remarkable when the voltage of the opposite polarity applied to the electrodes has a similar waveform to the electric field radiated from the display panel and is synchronized.

Therefore, according to the present invention, it is possible to inexpensively reduce the electric field radiation that is likely to adversely affect the human body.

If the amplitude of the voltage applied to the electrodes is adjusted, a voltage having a similar waveform to the electric field radiated from the display panel can be easily obtained.

In a liquid crystal display device driven by an alternating current, an alternating voltage applied to a common electrode provided in the liquid crystal display panel is a main cause of an electric field radiated from the display panel. Therefore, in this case, if an alternating voltage whose phase is inverted is applied to the electrodes, the electric field radiated from the display panel can be effectively canceled.

[0018]

FIG. 1 shows an embodiment of the present invention.
This embodiment is intended to suppress electric field radiation from the liquid crystal display device 1 driven by an alternating current.

The liquid crystal display device 1 includes a chassis frame 2 connected to the ground, and a liquid crystal display panel 3 is held by the chassis frame 2. Although not shown, the liquid crystal display panel 3 includes a common electrode. While the liquid crystal display device 1 is driven, the alternating voltage is continuously applied to the common electrode. A backlight 4 is provided on the rear surface of the chassis frame 2.

An electrode 5 is attached to the periphery of the liquid crystal display panel 3 on the chassis frame 2 via an insulating film (not shown). The electrode 5 is formed in a loop shape so as to surround the periphery of the liquid crystal display panel 3, and is made of, for example, a metal plate or a metal sheet.

A conductive wire 6 is connected to the electrode 5. The common electrode provided in the liquid crystal display panel 3 is connected to a phase inversion circuit 8 via a conductor 7, and an output of the phase inversion circuit 8 is supplied to the electrode 5 via a conductor 6. The phase inversion circuit 8 includes an operational amplifier 9 and a variable resistor 10 for providing an amplitude adjusting function.

During the operation of the liquid crystal display device 1, an electric field synchronized with the alternating voltage applied to the common electrode is radiated from the front surface of the display panel 3. In order to cancel this electric field, the conducting wire 7 connected to the common electrode is connected to the phase inversion circuit 8. Therefore, the signal input to the phase inversion circuit 8 has, for example, a waveform indicated by “11”. The signal output from the phase inversion circuit 8 has a waveform 12 obtained by inverting the waveform 11, and these are synchronized with each other. The output signal of the phase inversion circuit 8 is adjusted by the variable resistor 10 included in the phase inversion circuit 8 so that the amplitude becomes the most effective for canceling the electric field. The electrode 5 is provided. That is, this output signal has a voltage of the opposite polarity to the electric field radiated from the liquid crystal display panel 3.

As described above, the electric field radiated from the liquid crystal display panel 3 is effectively canceled by applying a voltage having the opposite polarity to the electric field to the electrode 5.

The operational amplifier 9 included in the above-described phase inversion circuit 8 may be replaced with another circuit or element having a phase inversion function, such as a circuit using a transistor. As for the vessel 10,
It may be replaced with a circuit or an element having another amplitude adjustment function.

FIGS. 2 to 4 show other embodiments of the present invention in which the arrangement of electrodes for applying a cancel voltage is changed.

Referring to FIG. 2, electrodes 13a and 13b made of a metal plate or a metal sheet are arranged on chassis frame 2 along the upper side and the lower side of liquid crystal display panel 3, respectively. These electrodes 13a and 13
A cancel voltage is applied to b through the conducting wire 14.

In FIG. 3, the liquid crystal display panel 3 is placed on the chassis frame 2 along each of the left and right sides thereof.
Electrodes 15a and 15 made of metal plate or metal sheet
b is arranged. These electrodes 15a and 15b have
A cancel voltage is applied via the conductor 16.

FIG. 4 shows the rear surface of the front panel 17 arranged so as to cover the periphery of the liquid crystal display panel. An electrode 19 made of a loop-shaped metal plate or metal sheet is attached so as to surround the periphery of the opening 18 of the front panel 17. This electrode 19 has a conductor 20
, A cancel voltage is applied. When the front panel 17 is made of resin, electrical insulation between the front panel 17 and the electrodes 19 is not required.
However, when there is a possibility that the electrode 19 comes into contact with a chassis frame made of metal, it is necessary to provide electrical insulation with the chassis frame.

Although the above-described embodiment has been described with reference to the liquid crystal display device 1 driven by AC, the cancel voltage is taken out from the common electrode, but such a cancel voltage is taken out from other circuit parts. You may.

The present invention can be applied to a flat display device such as a plasma display device other than the liquid crystal display device. Therefore, the cause of the electric field to be suppressed varies depending on the type of the flat display device, and therefore, the cancel voltage also varies depending on the type of the electric field to be suppressed. It is preferable to use a voltage derived from the current voltage as the cancel voltage.

[Brief description of the drawings]

FIG. 1 shows a device for suppressing electric field radiation from a liquid crystal display device 1 according to an embodiment of the present invention, and is a perspective view of the liquid crystal display device 1 and a circuit diagram for obtaining a voltage for suppressing electric field radiation. It is included.

FIG. 2 is a front view of a liquid crystal display device 1 according to another embodiment of the present invention.

FIG. 3 is a front view of a liquid crystal display device 1 according to still another embodiment of the present invention.

FIG. 4 is a rear view of a front panel 17 according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Chassis frame 3 Liquid crystal display panel 5, 13a, 13b, 15a, 15b, 19 Electrode 6, 7, 14, 16, 20 Conductor 8 Phase inversion circuit 9 Operational amplifier 10 Variable resistor 17 Front panel

Claims (4)

(57) [Claims] 1. A display panel having a common electrode,
A flag in which an alternating voltage is applied to a common electrode of the display panel.
A display frame, a chassis frame for holding the display panel, and an AC-driven drive disposed on the chassis frame.
And dynamic electrode, the electric field radiated from said display panel and means for applying a reverse polarity voltage to the drive electrode, suppressing the electric field radiation from the flat display device device. 2. A display panel having a common electrode,
A flag in which an alternating voltage is applied to a common electrode of the display panel.
In Tsu DOO display device, a front that is disposed so as to cover the periphery of the display panel
A panel and a drive arranged on the front panel and driven by an alternating current
Electrodes and a voltage having a polarity opposite to that of the electric field radiated from the display panel.
Means for applying a voltage to the drive electrode.
A device that suppresses electric field radiation from a spray device. Wherein means for applying a voltage of the opposite polarity to the driving electrode includes a means for amplitude adjustment of the opposite polarity of the voltage, the electric field radiation from the flat display device according to claim 1 or 2 A restraining device. 4. The means for applying the voltage of the opposite polarity to the drive electrode includes means for inverting the phase of the alternating voltage.
An apparatus for suppressing electric field radiation from the flat display device according to claim 1 .