JPH11143372A - Shielding structure for plasma display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shield interference electromagnetic waves radiated due to the drive of a plasma display. SOLUTION: A metallic casing 4 arranged on the rear of a panel 1 is electrically insulated from an external casing 5 and the casing 5 is grounded to a safety earth to completely shield interference electromagnetic waves radiated from electrodes in the panel 1, a driving circuit 2 and the casing 5. When a stand 7 is connected to the casing 5 by screws 8 consisting of an insulating material, the radiation of interference electromagnetic waves from the stand 7 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield structure of a plasma display having a plurality of linear electrodes.

[0002]

2. Description of the Related Art In a plasma display, a plurality of linear electrodes are arranged in a horizontal direction and a vertical direction, and one pixel is formed at an intersection. By applying a pulse voltage between these electrodes, a discharge occurs in the cell, and the RGB phosphors are excited by ultraviolet rays emitted by the discharge to emit light. At this time, the pulse voltage is a voltage of several tens V to several hundred V, and the switching frequency is several hundred k.
Hz.

[0003] When a pulse voltage is applied to the linear electrode group disposed in the panel to drive the panel, a high-frequency current flows through the linear electrode group. In addition, since there is a metal housing on the back of the panel, the electrodes in the panel and the metal housing are capacitively coupled to form a current loop between the electrodes in the panel and the drive circuit. The loop also causes the metal housing itself to act as an antenna, radiating electromagnetic interference waves, and adversely affecting other electronic devices. In order to shield such electromagnetic interference waves, use metal for the front cover and rear cover for the purpose of shielding the entire panel and ground it to the metal housing, and furthermore, the front surface to suppress radiation from the front of the panel The cover also used a transparent conductor to block electromagnetic interference waves radiated from the panel.

A stand for supporting the plasma display panel has been connected to the metal housing on the back of the panel by metal screws. At this time, since the metal casing is part of the charge / discharge current loop when driving the panel by capacitively coupling with the linear electrode in the panel, the screw also becomes a radiation source of interfering electromagnetic waves. The stands and screws were electrically insulated.

[0005]

In the plasma display configured as described above, since the GND of each drive circuit is connected to the metal housing, a large charge / discharge current when driving the panel causes the metal housing to generate a large charge / discharge current. It was flowing. As a result, a high-frequency current loop is formed between the drive circuit, the electrodes in the panel, and the metal casing, so that the panel and the casing are all sources of interference, and this interfering electromagnetic wave is transmitted to other electronic devices. Could have a negative effect. Therefore, in order to cut off this interfering electromagnetic wave, the drive circuit and the digital signal processing circuit were shielded by a metal body, but since this metal body was grounded to a metal housing through which a large charge / discharge current was flowing,
The effect of blocking electromagnetic interference was weakened.

Further, a stand for supporting the plasma display panel has been connected to a metal housing on the back of the panel by metal screws. At this time, since the metal housing is a radiation source of electromagnetic waves by being capacitively coupled to the linear electrodes in the panel, the stand connected by the metal screws is also a radiation source of interfering electromagnetic waves. Further, even when the stand and the screw are insulated, noise of the metal housing leaks to the stand due to the capacitive coupling between the stand and the screw, so that the stand is a radiation source of the disturbing electromagnetic wave.

[0007]

In order to solve the above-mentioned problems, a shield structure of a plasma display according to the present invention comprises:
Electrically insulates the metal housing and exterior housing on the back of the panel,
The outer housing is grounded to a safety ground. Further, a screw for supporting the stand on the plasma display panel main body is made of an insulating material, or an insulating material is interposed between the screw and a metal casing on the back surface of the panel.

According to the present invention, even when the metal housing on the back of the panel becomes a radiation source of the disturbing electromagnetic wave due to the charging / discharging current at the time of driving the panel, the metal housing and the outer housing are electrically connected. Insulating and grounding the exterior case to a safety ground allows the exterior case to maintain an equipotential without charging / discharging current flowing. The metal housing can be completely shielded.

Further, since the screws are made of an insulator, the metal housing and the stand are not capacitively coupled, and the stand does not become a source of interference. Further, even when an insulator is interposed between the screw and the metal housing, the metal housing and the screw are similarly insulated, so that even if the stand is fixed by the screw, the stand does not become a source of interference. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The shield structure of a plasma display according to the first aspect of the present invention is configured to electrically insulate a metal housing and an outer housing on a back surface of a panel and to secure the outer housing. It is characterized in that it is grounded to earth, and the metal housing serving as an obstruction source can be completely shielded by the outer housing which is kept at the same electric potential by the safety earth.

Next, a shield structure of a plasma display according to a second aspect of the present invention is characterized in that a screw connecting a stand and a plasma display panel body is made of an insulating material, and a metal housing is provided. This prevents noise from flowing through the screws and flowing into the stand.

Next, a shield structure of a plasma display according to a third aspect of the present invention is characterized in that an insulator is sandwiched between a metal housing and a screw.
Since the metal housing and the screw are insulated, the charge / discharge current flowing through the metal housing does not flow through the stand.

(Embodiment 1) The first aspect of the present invention will be described below.
An embodiment of the invention described in claim 2 will be described with reference to FIG.

FIG. 1 shows a housing structure of a plasma display. 1 is a plasma display panel, and 2 is a drive circuit. The output terminal of the drive circuit 2 is 3
Is connected to the electrodes in the panel 1 by the flexible cable. The panel 1 is attached to a metal case 4. At this time, a high pulse voltage is applied from the output terminal of the drive circuit 2 to the electrodes in the panel, so that the electrodes in the panel act as antennas and emit electromagnetic interference.

Further, the electrodes in the panel become capacitive loads when viewed from the drive circuit 2 due to the capacitive coupling between the panel 1 and the metal housing 4. Therefore, the charge / discharge current flowing through the electrodes in the panel becomes large, and the drive circuit 2 and the panel 1
All of the internal electrodes and the metal housing 4 are radiation sources of disturbing electromagnetic waves. Therefore, in order to cut off this interference source, the panel 1, the drive circuit 2, and the metal housing 4 are covered with a conductive exterior 5 and a conductive front panel 6,
By insulating the exterior 5 from the metal housing 4 and grounding the exterior to a safety ground, the exterior is maintained at the same potential and the internal sources of interference can be completely shut off.

Further, in order to fix the stand 7 for supporting the housing to the housing, the metal housing 8 is connected to the metal housing 4 by means of metal screws 8. At this time, the screws 8 and the metal housing 4 are electrically connected. Therefore, the screw 8 is also an interference source. Therefore, the stand 7 and the screw 8 are insulated by the insulator 9 to prevent the stand 7 from becoming an interference source. However, the capacitive coupling of the screw 8 and the stand 7 causes a charge / discharge current to flow through the stand 7 and eventually. It becomes a source of interference. Therefore, by making the screws 8 insulated, it is possible to prevent noise of the metal housing 4 from flowing into the stand 7.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a connection diagram of the metal case 4 and the screw 8 of the plasma display panel. The screw 8 is used to fix the plasma display panel to a stand.

In the embodiment of the present invention, when a stand (not shown) is fixed to the metal housing 7, the insulator 10 is interposed between the screw 8 and the metal housing 4 so that 4 can be prevented from flowing into the screw 8. Therefore, by preventing noise from flowing into the stand, it is possible to prevent the stand from becoming an interference source.

[0019]

As described above, according to the present invention, the electromagnetic interference radiated from the display panel of the plasma display having a plurality of linear electrodes is completely shielded by the outer casing grounded to the safety ground. Can be.

Further, by making the screws an insulator, it is possible to prevent noise from flowing from the metal housing to the stand. Also, by sandwiching an insulator between the screw and the metal housing, it is possible to similarly prevent noise from flowing into the stand.

[Brief description of the drawings]

FIG. 1 shows a structure of a housing of a plasma display according to Embodiment 1 of the present invention.

FIG. 2 is a connection diagram of a screw and a metal housing according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Panel 2 Drive circuit 3 Flexible cable 4 Metal housing 5 Exterior housing 6 Front plate 7 Stand 8 Screw 9, 10 Insulator

Claims (2)

[Claims] 1. A method for electrically separating a GND of a driving circuit of a plasma display panel, a metal body on a back surface of the plasma display panel, and a metal housing of an exterior of the plasma display panel, and The shield structure of the plasma display, which is connected to the ground. 2. A shield structure for a plasma display, wherein an insulator is sandwiched between a metal case on a back surface of the plasma display panel and a screw for fixing a stand supporting the plasma display panel.