Patent Publication Number: US-2007109220-A1

Title: Plasma display module

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
      This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0108299, filed on Nov. 12, 2005, which is hereby incorporated by reference for all purposes as if fully set forth herein.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a plasma display module, and more particularly, to a plasma display module having circuit boards whose number required to display images is reduced.  
      2. Description of the Related Art  
      Plasma display modules, which are flat display modules for displaying images using a gas discharge phenomenon, provide various advantages, such as a high display capacity, a high luminance, a high contrast, reduced afterimages, and a wide-range viewing angle. Plasma display modules have attracted considerable attention as next-generation flat display modules which can replace conventional cathode ray tube (CRT), because they can be thin and large in size compared with other flat display panels.  
       FIG. 1  is a diagram showing a structure of a conventional plasma display module. The plasma display module includes a plasma display panel  30  having a first panel  10  and a second panel  20 , and an X driver, a Y driver, and an address driver that apply driving signals to the plasma display panel  30 . A plurality of electrodes X, Y, and A that contribute to display discharge are arranged on the plasma display panel  30 . For example, a plurality of sustain electrodes X and a plurality of scan electrodes Y extending parallel to each other are arranged on the first panel  10 . A plurality of address electrodes A crossing the electrodes X and Y are arranged on the second panel  20 . The sustain electrodes X and the scan electrodes Y are electrically coupled to the X driver and the Y driver, respectively. The address electrodes A are electrically coupled to the address driver to receive a driving signal from the address driver. The sustain electrodes X and the scan electrodes Y alternate each other and make pairs. Display discharge occurs between a pair of a sustain electrode X and a scan electrode Y, whereby an image is obtained. A portion where a pair of electrodes X and Y crosses an address electrode A is defined as a sub-pixel  31 . Three sub-pixels emitting different colors, namely, R, G, and B sub-pixels  31 , constitute a pixel.  
      The plasma display panel  30  having this structure is driven by repeating a driving period including a reset period, an address period, and a sustain period. During the reset period, the charge states of all sub-pixels  31  become uniform. During the address period, address discharge occurs in selected sub-pixels  31  by applying sequentially-controlled address signals to the address electrodes A. Wall charges are accumulated in the sub-pixels  31  that have undergone address discharge, and a predetermined wall voltage is formed. During the sustain period, predetermined alternating current (AC) pulses in which a sustain discharge voltage alternate with a ground voltage are applied to all of the sustain electrodes X and the scan electrodes Y. In the sub-pixels  31  in which the wall voltage is formed by address discharge, a voltage equal to or higher than a discharge start voltage is formed by an overlap of the wall voltage with a sustain discharge voltage, whereby display discharge is generated.  
      As described above, in the conventional plasma display module, AC pulses should be applied to the sustain electrodes X and the scan electrodes Y, so that both the X driver and the Y driver should be provided to apply driving signals to the sustain electrodes X and the scan electrodes Y. However, each of the drivers is a high-priced circuit board on which a plurality of circuits are mounted, resulting in an increase in the manufacturing costs for image display devices.  
      The circuit board as each driver generates high heat according to its operation. If this high heat is not rapidly removed, the accumulated heat degrades the circuits on the circuit board, hindering smooth operations of the circuits. Hence, a special heat conduction structure is required to prevent heat from accumulating in a narrow case on which a plurality of circuit boards are integrated with one another. Furthermore, a circuit board that generates a periodical electrical signal makes noise or a vibration, and when the noise and vibration go outside, the quality of display is degraded. Thus, in a conventional plasma display module provided with a plurality of circuit boards, a special vibration damping structure for blocking external noise is required.  
     SUMMARY OF CERTAIN INVENTIVE ASPECTS  
      One aspect of the present invention provides a plasma display module having circuit boards where a certain circuit boards are [ 0009 ]Another aspect of the invention provides a plasma display module, comprising: a chassis base configured to support a plasma display panel and at least one driving cable, having first and second ends, wherein the first end is electrically connected to the plasma display panel, and wherein the second end is grounded via a portion of the chassis base.  
      Another aspect of the present invention provides a plasma display module comprising: a chassis base providing a grounding area and having a bent portion bent with respect to at least one edge of the chassis base, a plasma display panel supported in front of the chassis base, displaying images, circuit boards supported in rear of the chassis base, driving the plasma display panel and a plurality of driving cables electrically coupling the plasma display panel to the circuit boards, wherein at least one of the driving cables includes a first end connected to the plasma display panel and a second end that extends from the first end toward the chassis base and is pressed down on and contacts the bent portion, and a clip which presses the second end down on the bent portion and grounds the second end to the bent portion is fit on the bent portion.  
      Another aspect of the present invention provides a plasma display module comprising: a chassis base providing a grounding area and having a bent portion bent with respect to at least one edge of the chassis base, a plasma display panel supported in front of the chassis base and displaying images, the panel comprising a plurality of pairs of scan electrodes and sustain electrodes that cause display discharge, each pair including a scan electrode and a sustain electrode, and the first ends of the driving cables are electrically coupled to the sustain electrodes, circuit boards supported in rear of the chassis base, driving the plasma display panel and a plurality of driving cables electrically coupling the plasma display panel to the circuit boards and applying driving signals generated by the circuit boards to the electrodes of the plasma display panel, wherein each of the driving cables includes a first end electrically connected to the sustain electrodes and a second end that extends from the first end toward the chassis base and is pressed down on and contacts the bent portion, and a clip which presses the second end down on the bent portion and grounds the second end to the bent portion is fit on the bent portion.  
      In one embodiment, the at least one driving cable is a sustain electrode driving cable, wherein 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Embodiments of the invention will be described with reference to the drawings.  
       FIG. 1  is a diagram illustrating a structure of a conventional plasma display module.  
       FIG. 2  is a diagram illustrating a structure of a plasma display module according to an embodiment of the present invention.  
       FIG. 3  is an exploded perspective view of the plasma display module of  FIG. 2 .  
       FIG. 4  is an exploded perspective view of a grounding structure shown in  FIG. 3 .  
       FIG. 5  is a cross-section taken along line V-V of  FIG. 4 .  
       FIG. 6  is a magnified cross-section of a grounded portion shown in  FIG. 5 . 
    
    
     DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS  
       FIG. 2  is a diagram illustrating a structure of a plasma display module according to an embodiment of the present invention. Referring to  FIG. 2 , the plasma display module includes a plasma display panel  130  which forms an image using display discharge, and drivers electrically connected to the plasma display panel  130  to drive the same. The plasma display panel  130  includes a first panel  110  and a second panel  120  which face each other. A plurality of sub-pixels  131  are arranged horizontally and vertically in a space  135  where the first and second panels  110  and  120  overlap with each other. Each of the sub-pixels  131  may be defined as a space where a sustain electrode X and a scan electrode Y extending substantially parallel to each other cross an address electrode A. Three sub-pixels emitting different colors, namely, R, G, and B sub-pixels  131 , may constitute a pixel.  
      The sustain electrodes X and the scan electrodes Y alternate to form pairs. A predetermined image is formed by display discharge occurring in each pair of a sustain electrode X and a scan electrode Y. The address electrodes A, crossing the sustain and scan electrodes X and Y substantially parallel to each other, perform address discharge. Address discharge denotes auxiliary discharge that occurs between the scan electrodes Y and the address electrodes A and facilitates display discharge between the sustain and scan electrodes X and Y. Although not shown in  FIG. 2 , barrier ribs may be formed between adjacent sub-pixels  131  and define the sub-pixels  131  to obtain independent discharge spaces.  
      Terminal areas  110   a ,  110   b , and  120   a  where the electrodes X, Y, an A are electrically connected to the drivers occur are formed on the outskirts of the space  135  in which the plurality of sub-pixels  131  are arranged. In one embodiment, the scan electrodes Y and the Y driver are electrically coupled to each other on the terminal area  100   a  located at the left edge of the first panel  110 . In this embodiment, the terminal area  110   b , located at the right edge of the first panel  110 , used to ground the sustain electrodes X. In this embodiment, the address electrodes A and the A driver are electrically coupled to each other on the terminal area  120   a  located at the bottom edge of the second panel  120 . The scan electrodes Y are electrically connected to the Y driver and receives a controlled signal. The address electrodes A are electrically connected to the address driver and receives a driving signal. In one embodiment, the sustain electrodes X are grounded to a ground line, and a ground voltage Vg with a certain level is applied to all of the sustain electrodes X. Accordingly, in contrast with a conventional plasma display panel, a special X driver for applying a driving signal (e.g., non-ground voltage) to the sustain electrodes X is not required.  
      In a conventional plasma display module, an alternating pulse in which a sustain discharge voltage and a ground voltage alternate is applied to the sustain and scan electrodes X and Y during a sustain period when an image is displayed. However, in one embodiment of the present invention, an alternating pulse is applied to only the scan electrodes Y, and the ground voltage Vg is applied to the sustain electrodes X. For example, an AC voltage in which a positive sustain discharge voltage and a ground voltage alternate is applied to the sustain and scan electrodes X and Y in a conventional plasma display module. In contrast, in a plasma display module according to one embodiment of the present invention, an alternating pulse in which a positive sustain discharge voltage and a negative sustain discharge voltage alternate is applied to the scan electrodes Y and a ground voltage Vg with a certain level is applied to the sustain electrodes X. In this way, a sustain discharge voltage with the same level as that in a conventional art may be applied between the sustain and scan electrodes X and Y in the plasma display module according to one embodiment of the present invention. In another embodiment, the ground voltage Vg may be applied to the scan electrodes Y or address electrodes A. In this embodiment, one end of the corresponding driving cables may be grounded to the chassis base. Furthermore, a corresponding driver for the Y or A electrodes is not needed.  
       FIG. 3  is an exploded perspective view of the plasma display module of  FIG. 2 . Referring to  FIG. 3 , the plasma display module includes the plasma display panel  130  on which images are displayed, a chassis base  160  installed at the rear of the plasma display panel  130  and supporting the plasma display panel  130 , and a heat conduction sheet  140  interposed between the plasma display panel  130  and the chassis base  160 .  
      As described above with reference to  FIG. 2 , the plasma display panel  130  includes the first and second panels  110  and  120  on which a plurality of electrodes X, Y, and A that cause discharge are arranged. The plasma display panel  130  serves as an image display unit. A plurality of driving cables  150 X,  150 Y, and  150 A extend rearwards from edges of the plasma display panel  130 , and transmit controlled driving signals to the electrodes X, Y, and A. The driving cables  150 X denotes X driving cables that transmit a ground voltage to the sustain electrodes X, the driving cables  150 Y denote Y driving cables that are coupled to the scan electrodes Y to transmit a controlled driving signal to the scan electrodes Y. Also, the driving cables  150 A denote address driving cables that are coupled to the address electrodes A to transmit an address signal to the address electrodes Y. In one embodiment, each of the driving cables  150 X,  150 Y, and  150 A include a plurality of conductive patterns. The conductive patterns of the driving cables  150 X,  150 Y, and  150 A are coupled to the electrodes X, Y, and A.  
      The plasma display panel  130  may be coupled to the chassis base  160  by a dual adhesive tape  145 , with the heat conduction sheet  140  interposed between the plasma display panel  130  and the chassis base  160 . The dual adhesive tape  145  is attached along the edges of heat conduction sheet  140 . Since the heat conduction sheet  140  exists between the plasma display panel  130  and the chassis base  160 , it transmits the heat generated by the plasma display panel  130  to the chassis base  160 .  
      The chassis base  160  also serves as a heat conduction plate for the plasma display panel  130  and functions as a ground connection area because of its wide area. To achieve this, the chassis base  160  may be formed of metal having high heat and electricity conductivities, such as, aluminum Al. Because the chassis base  160  also serves as a support for the plasma display panel  130  at its front side and circuit boards  170  at its rear side, the chassis base  160  may have vertically bent portions  161  along its edges so as to reinforce the support intensity. In addition, special reinforcing members  163  may be installed on the rear surface of the chassis base  160 . In one embodiment, clips  190  grip the bent portion  161  on one edge of the chassis base  160 , that is, the left edge thereof. The clips  190 , which are used to closely attach the X driving cables  150 X to the chassis base  160 , will be described later.  
      The plurality of circuit boards  170  driving the plasma display panel  130  are installed on the rear surface of the chassis base  160 . Some of the circuit boards  170  serve as drivers for applying controlled driving signals to the electrodes X, Y, and A of the plasma display panel  130 . For example, a circuit board  170 Y to which the Y driving cables  150 Y are coupled corresponds to the Y driver shown in  FIG. 2 , and a circuit board  170 A to which the address driving cables  150 A are coupled corresponds to the address driver shown in  FIG. 2 . The circuit boards  170 Y and  170 A may be replaced by a single circuit board to which both the driving cables  150 Y and  150 A are coupled. Alternatively, the circuit boards  170 Y and  170 A may be replaced by at least two circuit boards electrically coupled to each other. In addition to the circuit boards  170 Y and  170 A, the circuit boards  170  may further include an SMPS circuit board, a logic circuit board, etc., that execute different functions.  
      In one embodiment, the X driving cables  150 X are not coupled to any of the circuit boards  170  and instead grounded to the chassis base  160 .  FIG. 4  is a perspective view of a grounding structure of each of the X driving cables  150 X shown in  FIG. 3 .  FIG. 5  is a cross-section taken along line V-V of  FIG. 4 . Referring to  FIGS. 4 and 5 , a first end  151  of the X driving cable  150 X is electrically coupled to a sustain electrode X of the first panel  110 . An anisotropic conductive adhesive  180  is interposed between the sustain electrode X and the X driving cable  150 X. The anisotropic conductive adhesive  180  is a conductive material that applies conductivity only in a direction in which the conductive material is pressed down. In one embodiment, the X driving cable  150 X is pressed down on the sustain electrode X with the anisotropic conductive adhesive  180  interposed therebetween, so that the X driving cable  150 X and the sustain electrode X are electrically coupled to each other. A junction of the sustain electrode X and the X driving cable  150 X may be sealed with a silicon sealant (not shown), for example, to insulate and protect the junction from external environments.  
      The first end  151  of the X driving cable  150 X may extend toward the rear surface of the plasma display panel  130  while forming a round curve. In one embodiment, a second end  152  of the driving cable  150 X is pressed down on and contacts the chassis base  160  by, for example, a clip  190  that grips a bent portion  161  of the chassis base  160 . In other words, the clip  190  presses the second end  152  of the driving cable  150 X down on the chassis base  160 . The second end  152  of the driving cable  150 X may be squeezed between the clip  190  and the chassis base  160  and fixed to the bent portion  161 . In another embodiment, the second end  152  of the driving cable  150 X may be coupled to the chassis base  160  via other fixing member, for example, a clamp or an adhesive tape. In still another embodiment, the second end  152  of the driving cable  150 X may be grounded to the chassis base  160  without the use of a fixing member. In this embodiment, the second end  152  may be directly connected to the chassis base  160  by, for example, inserting the end  152  to a hole (not shown) of the chassis base  160 .  
      In one embodiment, the clip  190  has a shape of nearly “c” to surround the bent portion  161 . The clip  190  may include two sidewalls  191  separated from each other having an aperture with a width W through which the chassis base  160  enters between the two sidewalls, and contacting both lateral surfaces of the chassis base  160 , and a coupling portion  193  coupling the sidewalls  191  to each other so that the sidewalls  191  can be elastically biased in directions facing each other so as to contact the lateral surfaces of the chassis base  160  with a predetermined pressure. The sidewall  191  of the clip  190  which starts contacting the X driving cable  150 X may have two slits  197  formed in a direction in which the X driving cable  150 X extends. The slits  197  are separated from each other by a gap corresponding to at least the width of the X driving cable  150 X. A cutout portion  195  cut out of the main body of the clip  190  by the slits  197  guides the X driving cable  150 X by pushing the X driving cable  150 X toward the chassis base  160 . Due to the formation of the slits  197  in the clip  190 , the cutout portion  195  of the clip  190  starting the contact with the X driving cable  150 X can be deformed within a predetermined range and thus can gently deform the X driving cable  150 X. When the X driving cable  150 X is sharply deformed by the clip  190 , edges of the X driving cable  150 X and the clip  190  may interfere with each other, and thus the X driving cable  150 X may be worn away. In addition, a bending resistance of the X driving cable  150 X causes it take the clip  190  long time and much effort to grip the X driving cable  150 X.  
      Pressing protrusions  192  having wedge shapes protrude from the sidewalls  191  of the clip  190  toward the chassis base  160 . The pressing protrusions  192  of the clip  190  press down on and contact the chassis base  160  or the driving cable  150 X. The pressing protrusions  192  firmly fixes the clip  190  to prevent the clip  190  fit on the chassis base  160  from being detached from the chassis base  160  by unexpected impacts.  
      When the clip  190  is in a free state, that is, not influenced by an external force, the gap W of the clip  190  is narrow. When the clip  190  is pressed by the bent portion  161  of the chassis base  160 , the gap W of the clip  190  is open wider to receive the bent portion  161 . In other words, the clip  190  may be elastic. The clip  190  fit on the bent portion  161  is pressed down on and contacts the lateral surfaces of the bent portion  161  by its own elasticity, so that the clip  190  is firmly fixed to the bent portion  161 . If the clip  190  is formed of a material providing predetermined elasticity, various materials may be used without restrictions. In one embodiment, when considering the fact that the clip  190  is exposed, the clip  190  is formed of an insulative material. For example, the clip  190  may be formed of plastic for convenience of processing.  
       FIG. 6  is a magnified cross-section of a grounded portion of the driving cable  150 X shown in  FIG. 5 . Referring to  FIG. 6 , the pressing protrusions  192  protrude from the sidewalls of the clip  190  toward the chassis base  160  and are pressed down on and contact the bent portion  161  with a predetermined pressure, so that the bent portion  161  is firmly fixed to the chassis base  160 . The X driving cable  150 X includes a conductive pattern layer  150   b  in which a ground voltage Vg is maintained and cover films  150   a  and  150   c  which cover both surfaces of the conductive pattern layer  150   b  to insulate the conductive pattern layer  150   b  from external environments. To attach the cover films  150   a  and  150   c  to the both surfaces of the conductive pattern layer  150   b , adhesive layers (not shown) may be formed between the conductive pattern layer  150   b  and the cover film  150   a  and between the conductive pattern layer  150   b  and the cover film  150   c . A portion of the cover film  150   a  corresponding to a portion of the driving cable  150 X that contacts the chassis base  160  by the clip  190  is removed off so that the exposed conductive pattern layer  150   b  electrically contacts the chassis base  160 . Alternatively, a dedicated driving cable having no insulation elements, such as, cover films, at a portion where the conductive pattern layer  150   b  faces the chassis base  160  may be used.  
      Compared with a convention plasma display module, a plasma display module according to one embodiment of the present invention can drive a plasma display panel using a reduced number of circuit boards. Thus, an image display apparatus including the plasma display module can be manufactured at drastically reduced costs. Furthermore, the costs and processes required to design means for conducting heat generated by circuit boards or damping vibrations generated by the circuit boards can be saved.  
      While the above description has pointed out novel features of the invention as applied to various embodiments, the skilled person will understand that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made without departing from the scope of the invention. Therefore, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations coming within the meaning and range of equivalency of the claims are embraced within their scope.