Abstract:
A display apparatus is provided. The display apparatus includes a display panel; a base chassis which is disposed on a surface of the display panel, includes a first surface having a convex area and a second surface opposite the first surface and having a concave area corresponding to the convex area of the first surface; a driving circuit which is connected to the display panel to operate the display panel; a connection element which attaches the driving circuit to the convex area of the first surface of the base chassis; and a conductor which is attached to the concave area of the second surface of the base chassis.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2009-0099261, filed Oct. 19, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Apparatuses and methods consistent with exemplary embodiments relate to a display apparatus, a base chassis and a manufacturing method thereof, and more particularly, to a display apparatus to reduce EMI emission, a base chassis, and a manufacturing method thereof. 
     2. Description of the Related Art 
     Flat display apparatuses are used for portable devices. Further, the display apparatuses are rapidly replacing cathode ray tube (CRT) displays due to development of the display technology in the large display field. 
     One of the shortcomings of display panels is that a large electromagnetic wave noise is generated while the display panels are operating, thereby causing electromagnetic interference (EMI) emission. 
     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 a human body as electronic energy and thus raises body temperature, thereby damaging bodily tissues and functions. 
     Therefore, there is a need for reducing EMI while operating a display panel. 
     SUMMARY 
     Exemplary embodiments may address at least the above problems and/or disadvantages and other disadvantages not described above. Also, exemplary embodiments are not required to overcome the disadvantages described above, and an exemplary embodiment may not overcome any of the problems described above. 
     Exemplary embodiments provide a display apparatus capable of reducing EMI emission by attaching a conductor to a base chassis, the base chassis, and a manufacturing method thereof. 
     According to an aspect of an exemplary embodiment, there is provided a display apparatus including a display panel, a base chassis which is disposed on a rear surface of the display panel and is manufactured in a pressing manner to have a concave area and a convex area, a driving circuit which is connected to the display panel to operate the display panel and is attached to the convex area on a rear surface of the base chassis through a connection element, and a conductor which is attached to the concave area. 
     The conductor may cover a space formed by the concave area and may be attached to the concave area to block EMI emitted through the connection element. 
     The EMI may be noise generated by the driving circuit when the driving circuit drives the display panel, and the EMI may be transmitted to the connection element and be emitted using the connection element as an antenna. 
     There may be a plurality of concave areas and a plurality of convex areas, and the conductor may be attached to a concave area corresponding to the convex area to which the driving circuit is attached through the connection element, from among the plurality of concave areas. 
     The display apparatus may be a plasma display apparatus, and the conductor may be attached to a concave area corresponding to a convex area to which an X driving circuit and a Y driving circuit in the driving circuit are attached through the connection element, from among the plurality of concave areas. 
     The conductor may include at least one of a conductive gasket tape, a copper tape, and a metal plate. 
     The pressing manner may be a burring manner. 
     The connection element may be a conductive screw which is inserted from the convex area to the concave area, may protrude within a space formed by the concave area, and may not protrude outside the space formed by the concave area. 
     According to an aspect of another exemplary embodiment, there is provided a base chassis which accommodates a display panel and a driving circuit which constitute a display apparatus, the base chassis including a convex area which is manufactured in a pressing manner and in which the driving circuit is mounted through a connection element, and a concave area which corresponds to the convex area and to which a conductor is attached to block EMI generated by the driving circuit when the EMI is emitted through the connection element. 
     The connection element may be inserted from the convex area, protrude from the concave area, and have the characteristics of a parabolic antenna to emit the EMI from the concave area. 
     According to an aspect of another exemplary embodiment, there is provided a method for manufacturing a base chassis, the method including manufacturing the base chassis in a pressing manner so that the base chassis has a concave area and a convex area, and attaching a conductor to the concave area of the base chassis to block EMI emitted through a connection element when the driving circuit is mounted in the convex area of the base chassis through the connection element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects will become more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  is a side-sectional view of a plasma display apparatus according to an exemplary embodiment; 
         FIG. 2  is a partially exploded perspective view of the plasma display apparatus; 
         FIG. 3  illustrates a front surface of a base chassis; 
         FIG. 4  illustrates a rear surface of the base chassis; 
         FIG. 5  illustrates a driving circuit which is attached to the rear surface of the base chassis; 
         FIG. 6  illustrates a method for operating a plasma display apparatus; 
         FIG. 7  illustrates a process of emitting EMI through a screw; 
         FIG. 8  illustrates a concave area covered by a conductor; 
         FIG. 9  is a flow chart illustrating a method for manufacturing a base chassis according to an exemplary embodiment; and 
         FIGS. 10A and 10B  illustrate amounts of emitted EMI when the concave area is not covered and covered by the conductor. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Certain exemplary embodiments are described in greater detail below with reference to the accompanying drawings. 
     In the following description, like drawing reference numerals are used for the 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 exemplary embodiments. However, exemplary embodiments can be practiced without those specifically defined matters. 
       FIG. 1  is a side-sectional view of a plasma display apparatus  100  according to an exemplary embodiment, and  FIG. 2  is a partially exploded perspective view of the plasma display apparatus  100 . The plasma display apparatus  100  meets electromagnetic wave standard for EMI and provides a viewer with viewable images. 
     The plasma display apparatus  100  may include a panel  110 , a thermal spread sheet (TSS)  120 , a gasket  130 , a base chassis  140 , a driving circuit  150 , and a cover  160 . 
     The panel  110  generates an image by exciting a fluorescent substance using a vacuum ultraviolet rays generated by internal gas electric discharge. The panel  110  may include an upper panel  111  and a lower panel  113 . The edge of the upper panel  111  is connected to the 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 Ne and Xe. 
     In each discharge cell, electrodes which are connected to the driving circuit  150  are arranged. When the driving circuit  150  supplies the voltage to the electrodes, the plasma display apparatus  100  operates. Detailed description of a method for operating the plasma display apparatus  100  is provided below. 
     A glass filter  114  is attached to or coated on an upper surface 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 as a single filter layer or as a plurality of filter layers which differ from each other according to their functions. 
     A filter layer for surface reflection prevention may prevent the 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 provided to the viewer 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 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 the rear surface of the lower panel  113  to prevent degradation of image quality caused by transmitting heat generated in the plasma display apparatus  100  only to a specific portion of the panel  110 . That is, the TSS  120  is used to dissipate heat from the plasma display apparatus  100 . 
     In addition, the TSS  120  is connected to the base chassis  140  through the gasket  130  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  to reduce EMI emission. The TSS  120  may be implemented as an E-Graf. 
     In this exemplary embodiment, the TSS  120  is used to dissipate heat and block EMI, but this is merely an example. Even when a sheet to dissipate heat and a sheet to block EMI are separately provided, technical idea of the inventive concept can be applied. Furthermore, if it is not necessary to dissipate heat or if heat can be dissipated by other methods, only a sheet to block EMI may be provided. 
     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 a return path can be formed between the TSS  120  and the base chassis  140 . 
     The base chassis  140  accommodates the driving circuit  150 , and grounds the electric current generated by the driving circuit  150 . The shapes of the base chassis  140  are described in detail with reference to  FIGS. 3 and 4 . 
       FIG. 3  the front surface of the base chassis  140 , and  FIG. 4  illustrates the rear surface of the base chassis  140 . 
     The base chassis  140  is manufactured in a pressing manner, thereby including concave portions and convex portions. In particular, since the base chassis  140  includes holes through which screws penetrate, the base chassis  140  can be manufactured in a burring manner of the pressing manner. 
     The front surface  180  of the base chassis  140  is attached to the gasket  130 . The front surface  180  of the base chassis  140  is flat and partially concave and includes concave portions  310 ,  312 ,  320 ,  322 ,  324  and convex portions  330 ,  340 ,  350 . The panel  110  and the TSS  120  are positioned in front of the base chassis  140  through the gasket  130 . The concave portions of the base chassis  140  are referred hereinafter to as concave areas. 
     The rear surface of the base chassis  140  is flat and partially convex and includes convex portions  410 ,  420 ,  430 ,  440 ,  450  and concave portions  460 ,  470 ,  480 . The driving circuit  150  is connected to the base chassis  140  through the screw. The convex portions of the base chassis  140  are referred hereinafter to as convex areas. The convex portions  410 ,  420 ,  430 ,  440 ,  450  of the rear surface  190  correspond to respective matching concave portions  310 ,  312 ,  320 ,  322 ,  324  of the front surface  180 . The concave portions  460 ,  470 ,  480  of the rear surface  190  correspond to respective matching convex portions  330 ,  340 ,  350  of the front surface  180 . 
     Returning to  FIGS. 1 and 2 , the driving circuit  150  may include an X driving circuit  210 , a Y driving circuit  220 , an address driving circuit  230 , a power supply circuit  240 , and a control circuit  250  as illustrated in  FIG. 2 . The X driving circuit  210 , the Y driving circuit  220 , and the address driving circuit  230  transmit an X electrode driving signal, a Y electrode driving signal, and an address electrode driving signal to the X electrodes, the Y electrodes, and the address electrodes respectively to drive the panel  110 . 
     The driving circuit  150  is disposed on the rear surface  190  of the base chassis  140 . Detailed description is provided with reference to  FIG. 5 . 
       FIG. 5  illustrates the driving circuit  150  which is attached to the rear surface  190  of the base chassis  140 . In  FIG. 5 , the address driving circuit  230  is not illustrated for convenience of description. The driving circuit  150  is connected to the rear surface  190  of the base chassis  140  through the screw. The screw penetrates the driving circuit  150  and the base chassis  140  in sequence, and protrudes from the front surface  180  of the base chassis  140 . 
     EMI is emitted from the screw protruding from the front surface  180  of the base chassis  140 . In order to block EMI, the screw protrudes within a space formed by the concave areas of the base chassis  140  but does not protrude outside the space formed by the concave areas of the base chassis  140 . The concave areas are covered by a conductor. 
     The detailed method for blocking EMI using the conductor is described below. 
     Returning to  FIGS. 1 and 2 , 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  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 be thus formed of a conductive material. 
     EMI generated while the plasma display apparatus  100  is operating is emitted to the front surface  180  of the base chassis  140  through the screw. As the premise of the principle of generating EMI, a method for operating the plasma display apparatus  100  is described below with reference to  FIG. 6 . 
       FIG. 6  illustrates a method for operating the plasma display apparatus  100 . 
     The panel  110  includes a plurality of pixels arranged in matrix form. In each pixel, an X electrode, a Y electrode, and an address electrode are formed. The panel  110  is operated in an address display separate (ADS) operating method in which the voltage is transmitted to each electrode so that each pixel emits light. In the ADS operating method, each sub-field of the panel  110  is divided into a reset section, an address section, and a sustain section. 
     The reset section eliminates 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 (addressed cells). The sustain discharge section alternately transmits the sustain voltage to the X electrode and the Y electrode and performs discharge to display an image on the addressed cells. 
     The X driving circuit  210  is connected to the X electrodes and transmits the driving voltage to the X electrodes to operate the panel  110 . The Y driving circuit  220  is connected to the Y electrodes and transmits the driving voltage to the Y electrodes to operate the panel  110 . In particular, the X driving circuit  210  and the Y driving circuit  220  perform sustain discharge of a selected pixel by inputting the sustain voltage to the X electrodes and the Y electrodes alternately. 
     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 having 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. 
     In order to operate the panel  110 , the X driving circuit  210 , the Y driving circuit  220 , and the address driving circuit  230  apply a high voltage of approximately 200V and a root mean square (RMS) current of greater than 2 A to each electrode, so when the plasma display apparatus  100  operates, energy of driving waves to generate discharge emits EMI using the screw, which connects the driving circuit  150  with the base chassis  140 , and acts as an antenna. 
     The process and principle of emitting EMI are described with reference to  FIG. 7 . 
       FIG. 7  illustrates a process of emitting EMI through the screw. As illustrated in  FIG. 7 , the driving circuit  150  is disposed at the rear surface  190  of the base chassis  140 , and is connected to the base chassis  140  through the conductive screw  700 . The conductive screw  700  is inserted from a side of the driving circuit  150  into the base chassis  140 , and protrudes into the concave area  710  of the front surface  180  of the base chassis  140 . 
     When the driving circuit  150  generates driving energy to drive the plasma display apparatus  100 , EMI is caused and transmitted from the driving circuit  150  to the conductive screw  700 . In particular, EMI moves from a head  720  to a tail  730  of the conductive screw  700  in a direction  740  and is emitted in the air. 
     Due to the structural feature of the concave area  710  of the front surface  180  of the base chassis  140 , the conductive screw  700  has the characteristics of a parabolic antenna. Accordingly, EMI moving from the head  720  to the tail  730  of the conductive screw  700  reflects off the concave area  710  of the front surface  180  of the base chassis  140  and is emitted from the front surface  180  of the base chassis  140 , as illustrated in  FIG. 7  by arrows  760 . 
     To solve this problem, in this exemplary embodiment, the concave area  710  is covered by a conductor  800 . Detailed description is provided with reference to  FIG. 8 . 
       FIG. 8  illustrates a concave area  710  covered by a conductor  800 . The conductor  800  covers the concave area  710  on the front surface  180  of the base chassis  140 , so EMI emitted from the conductive screw  700  can be stuck in a space formed by the concave area  710 . 
     In particular, the conductor  800  reflects, multi-reflects, or absorbs the EMI so that EMI may be trapped in the space formed by the concave area  710 . 
     In order to minimize the thickness or the volume of the conductor  800 , the conductor  800  may be formed as a conductive gasket tape, a copper tape, or a metal plate. 
     In addition, in order to fasten the base chassis  140  and the driving circuit  150  firmly, the screw  700  protrudes within the space formed by the concave area  710  but does not protrude outside the space. The reason why the screw  700  does not protrude outside the space formed by the concave area  710  is that if the screw  700  protrudes outside the space, the conductor  800  has to be formed in three dimensions to cover the concave area  710 . That is, if the screw  700  protrudes outside the space, the entire thickness of the plasma display apparatus  100  may be larger due to the protruded screw  700  and the conductor  800  to cover the protruded screw  700  and the concave area  710 . Therefore, the plasma display apparatus  100  cannot be lightweight and slim. 
     There may be a plurality of concave areas on the front surface  180  of the base chassis  140 . In particular, as can be seen in  FIGS. 4 and 5 , concave areas may be disposed in portions in which the driving circuit  150  is mounted, and if necessary, may be disposed in other areas. Even if a concave area is disposed in a portion in which the driving circuit  150  is not mounted, the conductor  800  may cover only the portions in which the driving circuit  150  is mounted. 
     Although only one mounting screw  700  is illustrated, multiple mounting screws may be used. Accordingly, the concave areas into which the mounting screws protrude may be covered with the conductor or other means to reduce EMI emission. Also, only one or few of such concave areas may be covered. 
       FIG. 9  is a flow chart illustrating a method for manufacturing the base chassis  140  according to an exemplary embodiment. 
     The base chassis  140  is manufactured in a pressing manner so that a portion which is connected to the driving circuit  150  has a concave area and a convex area (S 910 ). 
     Subsequently, the driving circuit  150  is mounted on the convex area using the conductive screw  700  (S 920 ), and the concave area from which the conductive screw  700  protrudes is covered by the conductor  800  (S 930 ). 
     The order of operations S 920  and S 930  may be reversed. That is, after the base chassis  140  is manufactured in a pressing manner (S 910 ), the concave area is covered by the conductor  800  (S 930 ) and then the driving circuit  150  is mounted on the convex area using the conductive screw  700  which protrudes within the space formed by the concave area (S 920 ). 
     Accordingly, if the driving circuit  150  drives the panel  110 , EMI emitted from the conductive screw  700  can be effectively blocked. 
     The effect of reducing EMI emission by covering the concave area using the conductor  800  is described with reference to  FIG. 10 .  FIGS. 10A and 10B  illustrate amounts of emitted EMI when the concave area is not covered and covered by the conductor  800 . 
     More specifically, in  FIG. 10A , the graph shows the amount of emitted EMI when the concave area  710  is not covered by the conductor  800 . In  FIG. 10B , the graph shows the amount of emitted EMI when the concave area  710  is covered by the conductor  800 . 
     The standard line  1010  indicates the standard of the amount of emitted EMI according to the international standard. The wave  1020  indicates values obtained by measuring EMI according to frequency based on the horizontal frequency, and the wave  1030  indicates values obtained by measuring EMI according to frequency based on the vertical frequency. 
     Therefore, the amount of emitted EMI based on the horizontal frequency or the vertical frequency is lower when the concave area  710  is covered by the conductor  800  than when the concave area  710  is not covered by the conductor  800 . In particular, comparing the quasi-peak (QP) when the concave area  710  is covered by the conductor  800  with the QP when the concave area  710  is not covered by the conductor  800 , the QP when the concave area  710  is covered by the conductor  800  is approximately 5 dB-10 dB lower than the QP when the concave area  710  is not covered by the conductor  800 . The QP indicates the quasi-peak of the amount of emitted EMI. 
     As described above, if the conductor  800  covers the concave area  710 , emission of EMI generated while the plasma display panel is operating can be effectively reduced. 
     In this exemplary embodiment, in order to reduce EMI generated when the base chassis  140  of the plasma display apparatus  100  is manufactured in a pressing manner, the conductor  800  is attached to the concave area  710 , but this is merely an example. Technical idea of the inventive concept can be applied to base chasses used in other display apparatuses such as liquid crystal displays (LCDs). 
     Consequently, EMI emitted from the front surface of the base chassis can be effectively reduced. In particular, EMI can be reduced with simplified manufacturing process and low cost by not using stud manner but using a pressing manner. 
     The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting. 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.