Abstract:
A display panel is mount behind a conductive structure with a gasket sandwiched between the panel and the conductive structure. ESD protection is provided by holes through the gasket between the panel and the conductive structure.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the protection of display devices that are susceptible to damage by electrostatic discharges (ESD).  
       BACKGROUND TO THE INVENTION  
       [0002]     Liquid crystal display (LCD) panels are widely used in electronic devices. However, these devices are susceptible to damage by ESD. For this reason, LCD panels are often installed in close proximity to conductive structures.  
         [0003]     It is known to mount an LCD panel behind an aperture in a conductive bezel. An elastomeric grommet-like gasket is mounted in the aperture to protect the LCD panel against mechanical shocks and the ingress of moisture.  
         [0004]     It has been found that electrostatic discharges can propagate across the surface of the gasket to the edge of an LCD panel, damaging it.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the present invention to provide a display panel installation arrangement which reduces the risk of ESD damage to the display panel.  
         [0006]     According to the present invention, there is provided an electronic device, for instance an instrument, a personal digital assistant (PDA) or a personal communication device such as a mobile phone (aka cell phone), comprising a conductive structure having an opening, a display panel viewable through said opening and a gasket having at least a portion thereof sandwiched between the display panel and said structure, wherein the gasket has an aperture extending between the display panel and said structure. The aperture or apertures provide a path to ground that has a lower impedance than the path through the display. Since the apertures are behind the structure, through which the display device panel is visible, they do not detract from the appearance of the device, irrespective of whether there is an additional external cover. The gasket may have a plurality of apertures extending between the display panel and said structure.  
         [0007]     The apertures may be closely spaced, e.g. 2 mm to 7 mm (preferably about 4 mm).  
         [0008]     The may have apertures have cross-sections that are circular or regularly polygonal. However, the apertures could be slits or slots or have other irregularly polygonal cross-sections. The holes may be small, e.g. having diameters of 0.5 to 2 mm, preferably about 1 mm. Thus the small amount of material removed does not have a significant adverse effect of the prevention of moisture and dust ingress and shock prevention properties of the gasket.  
         [0009]     The gasket may have a channel which receives at least a portion of the edge of said structure around said opening. However, the gasket could have an L-shaped cross-section with the upright of the L projecting at least partially through the opening in said structure. The gasket could even be flat.  
         [0010]     The gasket may extend fully or partially around the opening.  
         [0011]     The display panel may be an LCD panel or another display type that is susceptible to damage from ESD. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a front view of a mobile phone in which the present invention is embodied;  
         [0013]      FIG. 2  is a front view of the mobile phone of  FIG. 1  with its front cover and keymat removed;  
         [0014]      FIG. 3  is a partial section view of the mobile phone of  FIG. 1  along the line A-A;  
         [0015]      FIG. 4  is a perspective view of a grommet-like gasket of the mobile phone of  FIG. 1 ;  
         [0016]      FIG. 5  is a rear view of the gasket of  FIG. 4 ; and  
         [0017]      FIG. 6  is a rear view of the gasket of another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     Exemplary preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings.  
         [0019]     Referring to FIGS.  1  to  3 , a mobile phone  1 , according to the present invention, comprises a generally H-section frame  2  with a battery  3  mounted to the back of the frame  2  and a front cover  4  clipped to the front of the frame  2 . A rectangular aperture  5  is provided in the front cover  4  so that an LCD panel  6  can be viewed. The front panel  4  also has an array of holes through which the buttons  7  of an underlying keymat project. A transparent plastic sheet  8  is glued across the back of the aperture  5 .  
         [0020]     A printed circuit board (PCB)  10  is mounted to the front of the frame  2 . An LCD panel mount  11  is fixed to the front of the PCB  10 . The PCB  10  also carries various other electronic components  12  necessary for the functioning of the mobile phone  1 .  
         [0021]     A conductive shield  15  covers the PCB  10  between the frame  2  and the front cover  4 . The shield  15  extends from the front face of the frame  2  towards the front of the mobile phone  1  and across the front of the PCB  10 . The shield  15  bulges outwards in front of the LCD panel  6  and is apertured so that the LCD  6  can be viewed.  
         [0022]     A rubber grommet-like gasket  20  is mounted around the edge of the aperture in the shield  15 . The back face of the gasket  20  is in contact with the front of the LCD panel  6 .  
         [0023]     Referring additionally to  FIG. 4 , the gasket  20  is rectangular and relatively flat and has a channel  20   a  running around its edge. The channel  20   a  receives the edges of the shield  15 , surrounding the LCD aperture, when it is installed.  
         [0024]     Referring additionally to  FIG. 5 , a plurality of closely spaced, e.g. 2 mm to 7 mm (preferably 4 mm), circular cross-section holes  20   b  are provided through the rear flanges  20   c  of the gasket  20 . The holes  20   b  are 1 mm in diameter and are arranged in a straight line along each side of the gasket&#39;s central opening and are preferable as close to the bottom of the channel  20  as practicable. As shown in  FIG. 3 , the holes  20   b  are located within the periphery of the front face of the LCD panel  6 . Consequently, they lie sufficiently in the path of an electrostatic discharge propagating across the surface of the gasket  20  towards the periphery of the front face of the LCD panel  6  to prevent it reaching the LCD panel  6 .  
         [0025]     Referring to  FIG. 6 , in another embodiment which is substantially as described with reference to FIGS.  1  to  5 , the gasket  20  has its hole  20   b  arranged in two staggered lines along each side of its central opening.  
         [0026]     It will be appreciated that many modifications may be made to the embodiments described above. In particular, the shape and size of the gasket may be varied to suit the shape and size of the display panel. Also, the holes in the gasket may only need to be provided near parts of the display that are particularly susceptible to damage from ESD.