Abstract:
A display device including a display panel, a chassis base connected to the plasma display panel, the chassis base supporting the plasma display panel, and a flexible printed circuit having a driver integrated circuit thereon installed on the chassis base while being pressed by a protective plate. A step structure is formed on the chassis base where the flexible printed circuit is attached. Furthermore, the flexible printed circuit area where the driver integrated circuit is placed may be in contact with a heat dissipating material located in an accommodating portion formed in the chassis base.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present application claims priority to and the benefit of Korean Patent Application Nos. 10-2003-0075977 filed on Oct. 29, 2003 and 10-2004-0029980 filed on Apr. 29, 2004, both applications filed in the Korean Intellectual Property Office, the entire content of which are incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     (a) Field of the Invention  
         [0003]     The present invention relates to a display device, and in particular, to a display device that can dissipate heat efficiently from a tape carrier package (TCP) driver integrated circuit (IC) installed on the chassis base that applies an address voltage to a display panel from a driving circuit board.  
         [0004]     (b) Description of the Related Art  
         [0005]     One example of a commonly used display device is a plasma display device. It is well known that a plasma display device uses plasma generated by gas discharge to display an image on a plasma display panel. Conventionally, in the plasma display device, a flexible printed circuit (FPC) electrically connects electrodes printed on the plasma display panel to a driving circuit. The FPC has an IC that applies an address voltage to form a wall voltage selectively in each pixel in accordance with signals controlled by the driving circuit.  
         [0006]     For example, widely used structures using the FPC and the IC to apply the voltage are a chip on board (COB) structure in which the IC is installed on a printed circuit board (PCB), and a chip on film (COF) structure in which the IC is installed on a film composing the FPC. Another structure used recently and more frequently is the TCP, which is small and less expensive.  
         [0007]     A COF, COB, or TCP installed on the chassis base produces electromagnetic interference (EMI) as well as a substantial amount of heat. The heat is produced because the gas discharge occurs at least 8 times during {fraction (1/60)} second (1 TV field), in order to produce more than 256 gradations in the plasma display panel.  
         [0008]     Therefore, a reinforcing plate is installed in the COB or COF to reinforce its structure and to fix the COB or COF on the chassis base. The reinforcing plate also plays a role of efficiently dissipating heat generated in the IC to the outside.  
         [0009]     With the TCP, by contrast, a heat dissipating plate (or a heat sink) connected to the TCP is installed on the chassis base to dissipate heat from the driver IC to the air.  
         [0010]     The heat dissipating plate, installed with the TCP on the chassis base, presses the driver IC to the chassis base, with a stopper consisting of special means placed between the heat dissipating plate and the chassis base to maintain a predetermined space therebetween.  
         [0011]     In mass production of the plasma display device, however, the manufacturing tolerance of the chassis base can sometimes cause a non-perfect surface in terms of flatness, where the TCP is attached. In this case, the driver IC may be broken by the heat dissipating plate abnormally pressing the driver IC because the predetermined space is not maintained between the heat dissipating plate and the chassis base.  
         [0012]     In addition, the heat dissipating plate in this structure can crush the FPC of the TCP when the heat dissipating plate is fastened with uneven forces of screws. The uneven forces of the screws cause the heat dissipating plate to twist which results in tearing of the FPC.  
       SUMMARY OF THE INVENTION  
       [0013]     In accordance with the present invention, embodiments of a display device a provided which securely protect the TCP regardless of the conditions of both the chassis base where the TCP is installed and the heat dissipating plate pressing the TCP.  
         [0014]     According to an embodiment of the present invention, the display device comprises a display panel, a chassis base positioned parallel to the display panel, the chassis base supporting the display panel, an FPC placed in the back of the chassis base, the FPC having a driver IC thereon and extending to the electrodes of the plasma display panel for the electrical connection, and a protective plate placed in the vicinity of the FPC, pressing the FPC to the chassis base. A step structure is formed on the chassis base where the FPC is placed.  
         [0015]     The driver IC, facing the top of the step structure, is in contact with the top surface of the step structure. The step structure may be formed as a single body with the chassis base or as a separate structure to be installed on the chassis base. Further, the step structure may have a protruded area facing opposite the display panel.  
         [0016]     Additionally, a heat dissipating sheet may be placed between the FPC and the protective plate. The driver IC is packed in the TCP and installed on the FPC.  
         [0017]     A damping means may be also placed between the FPC and the step structure. The damping means is located in an accommodating portion that is formed on the step structure. The driver IC, facing the damping means, is in contact with the damping means. Here, the step structure may be formed as a single body with the chassis base or as a separate structure to be installed on the chassis base. The step structure is formed to have a protruded area facing the plasma display panel and a protruded area in a part in the opposite direction to the display panel.  
         [0018]     In accordance with another embodiment of the present invention, a heat dissipating material placed in the accommodating portion of the chassis base is in contact with the FPC having the driver IC in the display device.  
         [0019]     The accommodating portion may be a cavity formed on the chassis base itself, or a cavity formed on a reinforcing means installed in the chassis base. The reinforcing means may be made of a solid material having high thermal conductivity, such as aluminum, steel, or copper.  
         [0020]     The heat dissipating material is in a gel-phase and applies pressure to the driver IC. Furthermore, a cover plate may be installed to the chassis base. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a perspective view of a display device according to a first embodiment of the present invention.  
         [0022]      FIG. 2  is a sectional side view taken along line I-I in  FIG. 1 .  
         [0023]      FIG. 3  is a partial sectional side view showing a modification of the first embodiment of the present invention.  
         [0024]      FIG. 4  is a partial sectional side view of the display device according to a second embodiment of the present invention.  
         [0025]      FIG. 5  is a partial sectional side view showing a modification of the second embodiment of the present invention.  
         [0026]      FIG. 6  is a partial sectional side view of the display device according to a third embodiment of the present invention.  
         [0027]      FIG. 7  is a perspective view of the accommodating portion for a heat dissipating material of the display device according to the third embodiment of the present invention.  
         [0028]      FIG. 8  is a partial sectional side view of the display device according to a fourth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0029]     As shown in  FIGS. 1 and 2 , a display device in accordance with one embodiment of the present invention includes a PDP  12  and a chassis base  16 . The PDP  12  is attached by an adhesive means such as a double-sided tape on one side of the chassis base  16 , and a driving board  18  for driving the PDP  12  is attached by screw connections on the other side of the chassis base  16 . The chassis base  16  is placed substantially parallel to the PDP  12 , and a thermal conduction medium (or heat dissipation sheet, not shown) may be positioned therebetween. A front cover (not shown) is placed at the outside of the PDP  12 , and a back cover (not shown) is placed at the outside of the chassis base  16 . Combining all of the above list components constitutes an exemplary display device set.  
         [0030]     The PDP  12  and the driving board  18  are electrically connected via an FPC  21 , through which the PDP  12  receives electrical signals required for driving from the driving board  18 .  
         [0031]     A driver IC  23 , installed on the FPC  21 , selectively applies a voltage to the electrodes of the PDP  12  in accordance with the signals controlled by the driving board  18 . In the present embodiment, the driver IC  23  is packed in the TCP  25  and is connected to both the driving board  18  and the PDP  12 .  
         [0032]     In more detail of the TCP  25  structure, the FPC  21 , as shown in  FIG. 2 , is installed to the chassis base  16  by connection means such as screws while being pressed to the driver IC  23  by the protective plate (or heat dissipating plate)  32  placed at the rear of the FPC.  
         [0033]     For this purpose, holes  32   a  for the screws are formed in the protective plate  32  and at the locations in the chassis base  16  corresponding to the holes  32   a.    
         [0034]     On the other hand, a step structure as shown in  FIG. 2 , is formed in a section  13  of the chassis base  16  where the FPC  21  is attached. The step structure in the present embodiment has a protruded area  15  facing opposite the PDP  12 . The driver IC  23 , facing the topmost part of the step structure, is in contact with the topmost surface thereof.  
         [0035]     When the FPC  21  is installed with the protective plate  32  on the chassis base  16  in accordance with this structure, the FPC  21  circumvents the chassis base  16  and, due to the step structure, is given a clearance as indicated by B in the drawing.  
         [0036]     This structure prevents the FPC  21  from being fractured by a slightly twisted protective plate  32  by uneven fastening of the protective plate  32  to the chassis base  16 , or by an uneven surface of the FPC  21  attachment on the chassis base  16  resulting from thermal deformation thereof that occasionally occurs during the manufacturing process.  
         [0037]     Moreover, this structure for connecting the FPC  21  is expected to increase the efficiency of heat dissipation from the driver IC  23  because only the driver IC  23  is in contact with the chassis base  16 , providing more secure contact with a heat dissipating sheet  34  placed behind the driver IC  23 .  
         [0038]     The step structure of the chassis base  16  can be formed as a single body with the chassis base  16  itself as shown in  FIG. 2 , or as an embodiment having a separate structure  17  to be installed on the chassis base  16 ′ as shown in  FIG. 3 .  
         [0039]      FIG. 4  is a partial sectional side view of a display device according to a second embodiment of the present invention, and  FIG. 5  is a partial sectional side view showing a modification of the second embodiment of the present invention.  
         [0040]     Like the previous embodiment, the second embodiment adopts a step structure in the chassis base  16 ″ and provides the structure to prevent damage of the FPC  21  of the TCP  25 . At the same time, the structure increases the efficiency in the heat dissipation from the driver IC  23  by providing more contact pressure to the driver IC  23  while preventing damage thereof.  
         [0041]     The step structure of the chassis base  16 ″ in the present embodiment consists of a section  60  protruding toward the PDP  12  and a section  62  protruding in the opposite direction. A cavity-like accommodating portion  18   a  is formed in the step structure by this configuration, and an elastic damping means  36  is inserted therein. The thickness of the damping means  36  is preferably larger than the depth of the accommodating portion  18   a.    
         [0042]     In order for the driver IC  23  to be placed in contact with the damping means  36 , the protective plate  32  pressing the driver IC  23  is attached to the chassis base  18  while the FPC  21  circumvents the chassis base  18 . Because the driver IC  23  is in contact with the damping means  36 , the damping means  36  may reduce the contact-pressure exerted on the driver IC  23  and prevent its fracture under the pressure of the protective plate  32 .  
         [0043]     In terms of the protective plate  32 , this implies that a larger pressing force may be exerted on the driver IC  23 . In the present embodiment, this can increase the efficiency of heat dissipation due to better contact of the driver IC  23  with the heat dissipating sheet  34  placed behind the driver IC  23 .  
         [0044]     For the aforementioned role, the step structure of the chassis base  18  is formed in a single body with the chassis base itself, as shown in  FIG. 4 .  FIG. 5  shows a separate structure  19  to be attached to the chassis base  16 ′″ for the aforementioned role.  
         [0045]      FIG. 6  is a partial sectional side view of a display device according to a third embodiment of the present invention, and  FIG. 7  is a perspective view of the accommodating portion for the heat dissipating material.  
         [0046]     In addition, as displayed in  FIG. 6 , a reinforcing means  54 , placed along the direction of the TCP  45  arrangement and between the TCP  45  and the chassis base  46 , is attached by connection means such as a screw to the chassis base  46 .  
         [0047]     The reinforcing means  54  supports the TCP  45  and is made of a thermal conduction material such as aluminum, copper, or steel for better transfer of the heat generated from the TCP  45  to the chassis base  46 .  
         [0048]     For efficient heat dissipation from the TCP  45 , a heat dissipating sheet  56  is also placed between the cover plate  52  and the TCP  45 , and in particular, is centered to the area where the driver IC  43  is attached between the cover plate  52  and the TCP  45 .  
         [0049]     In accordance with the present invention, furthermore, a heat dissipation material  58  in a gel-phase is located in the accommodating portion  54   a  for the heat dissipating material  58  in the chassis base  46 , and the FPC  21  area where the driver IC  43  placed is in contact with the heat dissipating material  58 .  
         [0050]     The accommodating portion  54   a  for the heat dissipating material  58  can be formed into the shape of a cavity on the reinforcing means  54 , as clearly shown in  FIG. 7 , or a cavity  47   a  on the chassis base  47  itself, as shown in FIG.  8 .  
         [0051]     When the TCP  45  is installed accordingly on the chassis base  47 , the FPC  21  area where the driver IC  43  placed is in surface-contact with the heat dissipating material  58 , and therefore, the efficiency of heat dissipation is improved over the prior art.  
         [0052]     The increase in the efficiency of the heat dissipation makes it possible to use less force for attaching the TCP  45  to the chassis base  47  via the cover plate  52 . Consequently, it can prevent fracture of the driver IC  43  of the TCP  45  under the pressure of the cover plate  52 .  
         [0053]     On the other hand, even in the case of a great pressing force from the cover plate  52 , the heat dissipating material  58  placed behind the driver IC  43  may absorb the pressure to some extent so that the driver IC  43  may remain intact.  
         [0054]     Moreover, since the TCP  45  is installed on the chassis base  46 ,  47  while it is in contact with the heat dissipating material  58  located in the accommodating portions  54   a,    47   a,  it is possible to securely re-install the heat dissipation structure for the TCP  45  without re-spreading thermal grease on the attachment area of the driver IC  43 . It may therefore improve the installation procedure for installing the TCP  45 .  
         [0055]     As explained hereinabove, a display device according to the present invention improves the structure of the chassis where the TCP is attached so that the area of the FPC of the TCP in contact with the chassis base and/or the protective plate is minimized, and thereby the driver IC of the TCP can be securely protected and the heat from the driver IC can be dissipated efficiently.  
         [0056]     Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concept taught herein will appear to those skilled in the art to still fall within the spirit and scope of the present invention, as defined in the appended claims.