Patent Application
20110090201
This application claims priorities from Korean Patent Application Nos. 10-2009-0099264 and 10-2009-0109699, filed on Oct. 19, 2009 and on Nov. 13, 2009, respectively, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entireties.
1. Field
Apparatuses and methods consistent with the exemplary embodiments relate to a plasma display apparatus to reduce electromagnetic interference (EMI) emission, and more particularly, to a plasma display apparatus to reduce EMI emission using spread sheets.
2. Description of the Related Art
Flat display apparatuses are generally used for portable devices and are rapidly replacing cathode ray tube (CRT) displays due to development of large display technologies in the flat display field.
Plasma display panels (PDPs) are a kind of flat display apparatus which display text or graphics using light emitted from plasma generated by gas discharge. Compared with other kinds of flat display apparatuses, PDPs have high luminance, a high efficiency of light emission, and a wide viewing angle, and are thus widespread today.
One of the shortcomings of display panels is that large electromagnetic wave noise is generated while display panels are operating, thereby causing electromagnetic interference (EMI). That is, since a voltage of approximately 200 V and a root mean square (RMS) electric current of greater than approximately 2 A are transmitted to electrodes constituting a plasma display panel, energy of a driving wave causing discharge emits EMI using the electrodes on the panel as an antenna.
EMI causes electromagnetic wave noise interruption which may obstruct reception of a desired electromagnetic signal, thereby causing malfunctioning of an electronic device. In addition, EMI is absorbed in human bodies as an electronic energy and thus raises body temperature, thereby damaging tissues and functions of the body.
Therefore, there is a need for methods for reducing EMI while operating a display panel.
Exemplary embodiments address at least the above problems and/or disadvantages and other disadvantages not described above. Also, an exemplary embodiment is not required to overcome the disadvantages described above, and an exemplary embodiment may not overcome any of the problems described above.
An aspect of an exemplary embodiment provides a plasma display apparatus to reduce EMI emission using spread sheets.
According to an aspect of an exemplary embodiment, there is provided a plasma display apparatus including: a display panel which includes an upper panel, a driving electrode, and a lower panel; a plurality of conductive sheets of which first surfaces are connected to a rear surface of the lower panel; and a base chassis which is connected to second surfaces, opposite the first surfaces, of the plurality of conductive sheets through a plurality of conductive substances.
The plurality of conductive substances may be a plurality of conductive gaskets, and the base chassis may be connected to the second surfaces of the plurality of conductive sheets through at least one respective conductive gasket.
The plurality of conductive sheets may be a plurality of thermal spread sheets (TSSs) to dissipate heat from the plasma display apparatus, and the first surfaces of the plurality of conductive sheets may be connected to the rear surface of the lower panel in a form that the plurality of conductive sheets are arranged parallel to or perpendicular to a direction in which the driving electrode is arranged.
The plasma display apparatus may further include a driving circuit which is mounted on a surface of the base chassis opposite a surface of the base chassis which is connected to the plurality of conductive sheets, and which is connected to the driving electrode, wherein an electric current which is generated by the driving circuit and is transmitted to the driving electrode returns to the driving circuit through the plurality of conductive sheets and the base chassis.
The first surfaces of the plurality of conductive sheets may be connected to the rear surface of the lower panel in a divided form so as to reduce a return path of the electric current compared with when the plurality of conductive sheets are integrated as a single conductive sheet.
The first surfaces of the plurality of conductive sheets may be connected to the rear surface of the lower panel in the divided form that the plurality of conductive sheets are arranged parallel to or perpendicular to a direction in which the driving electrode is arranged.
The plurality of conductive sheets may be divided in a form that a capacitance formed between each conductive sheet and the driving electrode is reduced as compared with when the plurality of conductive sheets are integrated as a single conductive sheet.
An active area in which the driving electrode is arranged and from which electromagnetic interference (EMI) is emitted may be included in an area perpendicular to the lower panel, and an area for the plurality of conductive sheets may be included in an area perpendicular to the active area.
The conductive sheets may be E-Graf.
According to an aspect of another exemplary embodiment, there is provided a plasma display apparatus including: a first conductive sheet which is attached to a first area of a display panel; a second conductive sheet which is attached to a second area of the display panel and is spaced apart a predetermined distance from the first conductive sheet; and a base chassis which is connected to the first conductive sheet through at least one first conductive connection element, and is connected to the second conductive sheet through at least one second conductive connection element.
The predetermined distance may be a distance which is set to minimize a level of EMI generated by the display panel.
The first area of the display panel may be an area which is adjacent to an X driving circuit to drive the display panel, and the second area of the display panel may be an area which is adjacent to a Y driving circuit to drive the display panel.
According to an aspect of another exemplary embodiment, there is provided a plasma display apparatus, including: a first conductive sheet of which a first surface is attached to a first area of a display panel; a second conductive sheet of which a first surface is attached to a second area of the display panel and is spaced apart a predetermined distance from the first conductive sheet; and a base chassis which is partially connected to a second surface, opposite the first surface, of the first conductive sheet, and is partially connected to a second surface, opposite the first surface, of the second conductive sheet.
The above and/or other aspects will be more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which:
Certain exemplary embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings. In the following description, like drawing reference numerals are used for like elements, even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the exemplary embodiments. However, the exemplary embodiments can be practiced without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the exemplary embodiments with unnecessary detail.
Referring to
The panel 110 realizes an image by exciting a fluorescent substance using vacuum ultraviolet rays generated by an internal gas electric discharge. The panel 110 may include an upper panel 111 and a lower panel 113. An edge of the upper panel 111 is connected to an edge of the lower panel 113 using a sealing substance 112 such as frit so as to form a single panel 110. A plurality of discharge cells are formed in a space between the upper panel 111 and the lower panel 113 sealed by the sealing substance 112, and each discharge cell is filled with neon (Ne) and xenon (Xe).
In each discharge cell, electrodes which are connected to the driving circuit 150 are arranged. If the driving circuit 150 supplies the voltage to the electrodes, the plasma display apparatus 100 operates. A detailed description of a method for operating the plasma display apparatus 100 according to an exemplary embodiment is given below.
A glass filter 114 is attached to or coated on an upper side of the upper panel 111 for surface reflection prevention, color correction, near infrared ray absorption, EMI blocking, etc. The glass filter 114 may be formed in a single filter layer or in a plurality of filter layers which differ from each other according to their function.
A filter layer for surface reflection prevention may prevent a viewer from viewing glare and prevent scratches and static electricity on the surface. A filter layer for color correction and color purity improvement prevents light having a wavelength between 580 nm and 590 nm from being emitted to the viewer so as to enhance a color correction range and correct white deviation.
A filter layer for near infrared ray absorption prevents light having a wavelength between 800 nm and 1200 nm from being emitted to the viewer so as to prevent malfunctioning of the plasma display apparatus 100 by interference with a wavelength band of a remote control. A filter layer for EMI blocking reduces EMI emitted toward the front surface of the panel 110.
The TSS 120 is attached onto a rear surface of the lower panel 113. The TSS 120 is used to dissipate the heat from the plasma display apparatus 100.
In addition, the TSS 120 is connected to the base chassis 140 through the gasket 130 so as to block EMI. That is, since energy of a driving wave causing discharge emits EMI using the electrodes on the panel 110 as an antenna by the voltage and the current which are applied to the X electrodes and the Y electrodes, the TSS 120 is connected to the base chassis 140 through the gasket 130 so as to reduce EMI emission. In particular, the TSS 120 may be divided into portions so as to shorten a return path of electric current, thereby reducing EMI emission. Detailed methods for blocking EMI according to exemplary embodiments are described later. The TSS 120 may be implemented as an E-Graf.
In this exemplary embodiment, the TSS 120 is used to dissipate the heat and block the EMI, but this is merely an example. Even when a sheet to dissipate the heat and a sheet to block the EMI are separately provided, technical aspects of the exemplary embodiments can be applied. Furthermore, if it is not necessary to dissipate the heat or if the heat can be dissipated by other methods, it is also possible to provide only a sheet to block the EMI.
In order to connect the TSS 120 with the base chassis 140, the gasket 130 may be formed of a bondable substance. In particular, in order to transmit the electric current from the TSS 120 to the base chassis 140, the gasket 130 is formed of a conductive material such as a metal fabric. That is, the gasket 130 connects the TSS 120 and the base chassis 140 electrically so that the base chassis 140 can be used as the ground and the return path can be provided between the TSS 120 and the base chassis 140.
There may be two gaskets 130 as illustrated in
The base chassis 140 accommodates the driving circuit 150, and grounds the electric current generated by the driving circuit 150. In particular, the base chassis 140 grounds the electric current which is generated by the driving circuit 150 and is transmitted through the electrodes which are connected to the driving circuit 150, a panel capacitor, the TSS 120, and the gasket 130.
The driving circuit 150 may include an X driving circuit, a Y driving circuit, an address driving circuit, a power supply circuit, and a control circuit, as illustrated in
The cover 160 covers a portion of the front surface of the panel 110, and the side and the rear surface of the panel 110 so as to prevent damage of the panel 110 and the driving circuit 150. The cover 160 may block EMI emitted from the back of the plasma display apparatus 100, and may thus be formed of a conductive material.
Hereinafter, a method for operating the plasma display apparatus 100 according to an exemplary embodiment is described with reference to
Referring to
The address driving circuit 230 transmits a data signal to select a pixel on which an image is displayed to an address electrode. The X electrodes and the Y electrodes are at right angles to the address electrodes, and face each other with a discharge space therebetween. The discharge space in which the X electrodes, the Y electrodes, and the address electrodes cross one another forms the discharge cells.
A detailed structure of the panel 110 according to an exemplary embodiment is described with reference to
Referring to
After the ITO electrodes 310 are patterned on the upper glass 300, bus electrodes (i.e., the X electrodes and the Y electrodes) 320 are patterned on the ITO electrodes 310. The X electrodes and the Y electrodes alternately receive the sustain voltage and perform a sustain discharge for a selected pixel.
After the bus electrodes 320 are patterned on the ITO electrodes 310, black stripes 330 are patterned on the upper glass 300. The black stripes 330 are provided between the pixels so as to maintain the separated state between the pixels.
After the black stripes 330 are patterned on the upper glass 300, a dielectric layer 340 and a magnesium oxide (MgO) protective layer 350 are disposed thereon. The dielectric layer 340 and the MgO protective layer 350 generate plasma stably by maintaining insulation between the address electrodes and the bus electrodes 320, and prevent the electrodes from being eroded by the plasma.
Referring to
After the address electrodes 410 are patterned on the lower glass 400, a dielectric layer 420 is disposed thereon. As described above, the dielectric layer 420 generates plasma stably by maintaining insulation between the address electrodes 410 and the bus electrodes 320, and prevents the electrodes from being eroded by the plasma.
Partitions 430 are formed or provided on the dielectric layer 420. The partitions 430 block a fluorescent substance so that a red (R) pixel, a green (G) pixel, and a blue (B) pixel can be distinguished.
After the partitions 430 are provided on the dielectric layer 420, a fluorescent substance 440 is formed between the partitions 430 and then the sealing substance 112 such as frit is filled therein. By this process, the lower panel 113 is manufactured.
After the upper panel 111 and the lower panel 113 are manufactured, assembly and bonding of the upper panel 111 and the lower panel 113, gas injection, aging, lighting inspection, etc., are performed so that the panel 110 is formed as illustrated in
Referring to
The reset section eliminates a previous wall charge state and sets up wall charges to perform the next address discharge stably. The address section selects turned-on cells and turned-off cells and stacks wall charges in the turned-on cells (i.e., addressed cells). The sustain discharge section alternately transmits the sustain voltage to the X electrode and the Y electrode and performs a discharge to display an image on the addressed cells.
The panel 110 is operated by creating the discharge using a difference between the voltage transmitted to the X electrode and the voltage transmitted to the Y electrode and emitting light using plasma generated by discharge.
As described above, the X electrodes and the Y electrodes face each other with a discharge space therebetween. The discharge space in which the X electrodes, the Y electrodes, and the address electrodes cross one another forms the discharge cells.
The form of arrangement of the X electrodes and the Y electrodes is related to the form of division of the TSS 120, and is thus described with reference to
As described above, the X driving circuit 210 and the Y driving circuit 220 alternately input the sustain voltage to the X electrodes and the Y electrodes, so that the electric current is transmitted to the X electrodes and the Y electrodes and a sustain discharge of a selected pixel is caused.
The X electrodes are connected to the X driving circuit 210, and the electric current is transmitted in the X electrodes from the X driving circuit 210 to the Y driving circuit 220. The Y electrodes are connected to the Y driving circuit 220, and the electric current is transmitted in the Y electrodes from the Y driving circuit 220 to the X driving circuit 210. Since a high voltage of approximately 200 V and an RMS electric current of greater than approximately 2 A are transmitted to the X electrodes and the Y electrodes, energy of a driving wave creating the discharge emits EMI using the electrodes on the panel 110 as an antenna.
In order to solve this problem, EMI emitted from the X electrodes and the Y electrodes is transmitted to the TSS 120 and is grounded by the base chassis 140. In order to solve this problem more effectively, the TSS 130 which is divided into a plurality of portions is used and is connected to the base chassis 140 through the gaskets 130.
In particular, since the X electrodes and the Y electrodes are disposed horizontally, that is, from the X driving circuit 210 to the Y driving circuit 220 or from the Y driving circuit 220 to the X driving circuit 210, the TSS 120 which is divided vertically is used to shorten the return path of the electric current.
A detailed description is given with reference to
The TSS 120 is divided into two portions, that is, a left portion 120-1 and a right portion 120-2, and is attached to the rear surface of the lower panel 113. Each portion 120-1 and 120-2 of the TSS 120 is not connected directly to the base chassis 140, but is connected to the base chassis 140 through each gasket 130-1 and 130-2.
If the electric current transmitted to the X electrodes and the Y electrodes is transmitted to the TSS 120, the TSS 120 forms a capacitance using the lower panel 113 as a dielectric substance.
In addition, the electric current transmitted to the TSS 120 is transmitted back to the base chassis 140 through the gaskets 130 which are connected to the TSS 120, and is transmitted back to the driving circuit 150 which is connected to the base chassis 140. Consequently, the electric current generated by the driving circuit 150 returns to the driving circuit 150 through the electrodes, the TSS 120, the gaskets 130, and the base chassis 140, and the capacitance is formed between the electrodes and the TSS 120.
The reason for the TSS 120 having the divided portions 120-1 and 120-2 is that if a path along which the electric current returns is large, the capacitance between the electrodes and the TSS 120 increases, thereby comparatively increasing EMI emission, whereas if a path along which the electric current returns is small, the capacitance between the electrodes and the TSS 120 decreases, thereby comparatively reducing EMI emission.
The reason that the TSS 120 is connected to the base chassis 140 through the gaskets 130 is that the TSS 120 is partially connected to the base chassis 140 through the conductive substance so as to form a return path of the electric current. The return path of the electric current is described below.
The electric current which is generated in the electrodes and is transmitted to a left TSS 120-1 returns to the driving circuit 150 through the gasket 130-1 attached to the left TSS 120-1 and the base chassis 140. The electric current which is generated in the electrodes and is transmitted to a right TSS 120-2 returns to the driving circuit 150 through the gasket 130-2 attached to the right TSS 120-2 and the base chassis 140.
Accordingly, compared with a TSS having only a single portion, the TSS 120 having the two portions 120-1 and 120-2 has a small return path. In addition, as described above, since the return path becomes small, the capacitance between the electrodes and the TSS 120-1 and 120-2 decreases, thereby comparatively reducing EMI emission.
In this exemplary embodiment, the reason that the TSS 120 is vertically divided into the two portions 120-1 and 120-2 is that since the X electrodes and the Y electrodes are formed from left to right or from right to left, the return path of the electric current is formed from left to right or from right to left. In order to reduce the return path, the TSS 120 is vertically divided into the two portions 120-1 and 120-2.
However, dividing the TSS 120 into the two portions 120-1 and 120-2 including the left and right portions is merely an example for convenience of description. The technical aspects of the exemplary embodiments can be applied when horizontally dividing the TSS 120 into two portions, when vertically and horizontally dividing the TSS 120 into four portions, or when dividing the TSS 120 into more than four portions.
The TSS 120 does not need to be divided in a predetermined division method in an exemplary embodiment, but may be divided in various methods or various forms according to the size of the plasma display apparatus 100 or the usage environment. That is, even though divided forms of the TSS 120, the size of the divided portions, and the distance between the divided portions may vary, if these are performed to reduce the return path of the electric current, the technical aspects of the exemplary embodiments can be applied thereto.
The divided portions 120-1 and 120-2 of the TSS 120 do not need to be connected to the base chassis 140 through one respective gasket 130, but may be connected to the base chassis 140 through two or more respective gaskets 130. However, in order to form the return path of the electric current of the electrodes from the TSS 120 to the base chassis 140, the divided portions 120-1 and 120-2 of the TSS 120 are connected to the base chassis 140 through at least one respective gasket 130.
This is merely an example. It is also possible to connect the TSS 120 directly to the base chassis 140 without the gasket 130. In this case, however, in order to return the electric current of the electrodes, the divided portions of the TSS 120 may be partially connected to the base chassis 140.
As illustrated in
The gasket 130 is attached to the TSS 120 in this manner so as to minimize the return path of the electric current. The gasket 130 may be attached to the TSS 120 in other manners, and may be attached to the TSS 120 in a manner in which EMI emission is minimized according to the experimental results.
The TSS 120 is attached to an active area of the panel 110. The active area is described with reference to
The active area 510 indicates an area in which the electrodes are arranged. As illustrated in
That is, the active area in which the electrodes are arranged and from which EMI is emitted is included in an area perpendicular to the lower panel 113, and the TSS 120 is included in an area perpendicular to the active area.
As described above, since EMI is emitted due to the voltage and the electric current which are transmitted to the X electrodes and the Y electrodes, the TSS 120 having the portions 120-1 and 120-2 divided to block EMI does not need to be attached to the entire area of the rear surface of the lower panel 113, and is attached to an area 520 which is the same as or smaller than the active area 510.
Hereinafter, the effect of EMI emission reduced using the TSS 120 having the divided portions 120-1 and 120-2 is described with reference to
In
In particular, a reference line 810 is the reference of an amount of emitted EMI according to the international standard, wave I 820 is a value of EMI measured according to each frequency based on a horizontal frequency, and wave II 830 is a value of EMI measured according to each frequency based on a vertical frequency.
As illustrated, an amount of emitted EMI when the TSS 120 is divided according to an exemplary embodiment is lower than an amount of emitted EMI when the TSS 120 is not divided, regardless of the horizontal frequency or the vertical frequency. In particular, comparing the peak/quasi-peak (QP) when the TSS 120 is divided with the peak/QP when the TSS 120 is not divided, the peak/QP when the TSS 120 is divided is approximately 5 dB-10 dB lower than the peak/QP when the TSS 120 is not divided. The QP indicates the quasi-peak of the amount of emitted EMI.
As described above, emission of EMI generated while the plasma display panel is operating can be effectively reduced by using the TSS 120 of the divided structure according to the exemplary embodiments.
The foregoing exemplary embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-0099264 | Oct 2009 | KR | national |
| 10-2009-0109699 | Nov 2009 | KR | national |
