Abstract:
A shielding device for preventing an antenna signal from interference is disclosed. The shielding device includes a grounding component and a shielding plate. The shielding plate is made of a conductive material. The shielding plate has a first portion and a second portion. The first portion is grounded through the grounding component. The second portion is placed between an antenna and a display controller, so that the shielding plate can prevent the antenna from being interfered by the frequency component of the display controller.

Description:
RELATED APPLICATIONS 
   The present application is based on, and claims priority from, Taiwan Application Serial Number 94217923, filed Oct. 17, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The invention relates to a shielding device and, in particular, to a shielding device that prevents the antenna signal of a notebook computer from interference. 
   2. Related Art 
   Notebook computers have limited volumes. However, there are more and more devices to be integrated into a single notebook computer. The work frequency is also getting higher. Therefore, it is necessary to provide good shielding to prevent interference among devices. Modem notebook computers are already integrated with antennas for wireless communication functions. The antenna is usually integrated in the panel bracket of the display panel. The antenna transmits signals via electromagnetic (EM) waves. However, the panel itself has a liquid crystal display (LCD) driver that generates a video clock with the frequency about 65 MHz. Some high frequency components of the video clock overlap with the frequencies of the antenna operating in the 802.11 b/g band, thus interfering with the antenna signals. Therefore, how to design a shielding device to prevent the antenna of a notebook computer from interference with the video signals is very important. 
   SUMMARY OF THE INVENTION 
   An objective of the invention is to provide a shielding device to prevent the antenna signals of a notebook computer from interference. 
   Another objective of the invention is to provide a notebook computer that can prevent the antenna signals from interference. 
   Yet another objective of the invention is to provide a shielding device that can prevent the high frequency components of the LCD driver from interfering with other devices. 
   In accord with the above-mentioned objectives, the invention provides a shielding device to prevent the antenna signals of a notebook computer from interference. According to a preferred embodiment of the invention, the shielding device includes a grounding component and a shielding plate. The shielding plate is made of conductive material. The shielding plate has a first portion and a second portion. The first portion is electrically connected to a grounding device via the grounding component. The second portion is disposed between an antenna and a display controller. The shielding plate prevents the frequency components of the display controller from interfering with the antenna. The antenna is located in the panel bracket of the display panel. The display controller is a LCD driver. The grounding component is a metal foil. The metal foil attaches the first portion of the shielding plate to the grounding device. The metal foil and the grounding device are connected electrically. 
   The invention provides a notebook computer that can prevent the antenna signals from interference. According to a preferred embodiment of the invention, the notebook computer includes a host part, a panel part, and a shielding device. 
   The panel part is connected to the host part. The panel part has a grounding device. The panel bracket of the panel part contains an antenna. The shielding device includes a grounding component and a shielding plate. The shielding plate is made of a conductive material. The shielding plate has a first portion and a second portion. The first portion is electrically connected to the grounding device via the grounding component. The second portion is disposed between the antenna and a display controller. The shielding plate prevents the frequency components of the display controller from interfering with the antenna frequencies. The display controller is a LCD driver. The grounding component is a metal foil. The metal foil and the grounding device are connected electrically. 
   The invention has at least the following advantages, wherein each embodiment has one or many of the advantages. The disclosed shielding device can prevent the antenna signals of a notebook computer from interference. The disclosed shielding device can prevent the high frequency components of a display driver from interference. The invention provides a notebook computer that can prevent its antenna signals from interference. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects and advantages of the invention will become apparent by reference to the following description and accompanying drawings which are given by way of illustration only, and thus are not limitative of the invention, and wherein: 
       FIG. 1  is a schematic view of a notebook computer; 
       FIGS. 2 and 3  are schematic views of the shielding device according to an embodiment of the invention; 
       FIG. 4  is a schematic view of another embodiment of the invention; 
       FIG. 5  shows the structure of the back of the shielding device  202  of  FIG. 3 ; and 
       FIG. 6  is a schematic view of yet another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic view of a notebook computer  100 . The notebook computer  100  includes a panel part  115  and a host part  116 . The panel part  115  is connected to the host part  116 . For the convenience of explanation, the LCD panel  102  and the panel back shielding  104  of the notebook computer  100  are depicted separately. The LCD panel  102  is to be connected to the inner side  106  of the panel back shielding  104 . The outer side  108  of the panel back shielding  104  is the top cover of the notebook computer  100 . 
   The antenna  112  of the notebook computer is located in the panel bracket  110 . The LCD panel  102  contains a display controller  114 , such as a LCD driver. The LCD driver  114  generates a video clock. Since the video clock is a periodic square wave (or close to a periodic square wave), some high frequency components in the video clock may overlap with the antenna frequencies, thus interfering with the antenna signals. When the antenna  112  and the LCD driver  114  are close to each other, the interference phenomena become more prominent. 
     FIGS. 2 and 3  show schematic views of the shielding device in an embodiment of the invention. The shielding device  202  is used to prevent the antenna signals o the notebook computer from interference.  FIG. 2  depicts a schematic view of the shielding device  202  not yet completely finished.  FIG. 3  depicts a schematic view of the finished shielding device  202 . The shielding device  202  includes a grounding component  204  and a shielding plate  206 . The shielding plate  206  is made of a conductive material, such as the stainless steel. The shielding plate  206  has a first portion  208  and a second portion  210 . The first portion  208  is electrically connected to a grounding device  212  of the panel part via the grounding component  204  (such as the panel back shielding  104  shown in  FIG. 1 ). The second portion  210  is disposed between the antenna  214  and the display controller (whose relative position is shown by the LCD driver  114  in  FIG. 1 ). The shielding device  202  prevents high frequency components of the display controller from interfering with the antenna  214 . 
   The grounding component  204  may be a metal foil, such as the aluminum foil. The metal foil attaches the first portion  208  of the shielding plate  206  to the grounding device  212 . The metal foil and the grounding device  212  are electrically connected. 
   The grounding component  204  may also be a conductive tape, such as the aluminum tape. The conductive tape attaches the first portion  208  of the shielding plate  206  to the grounding device  212 . The conductive tape and the grounding device  212  are electrically connected. 
   With simultaneous reference to  FIG. 1 , the panel back shielding  104  is connected via a hinge to the notebook computer  100  and electrically connected to the base shielding of the host part  116 . Therefore, the grounding reference levels of the panel part  115  and the host part  116  of the notebook computer  100  are the same. 
     FIG. 4  is a schematic view of another embodiment of the invention. The structure of the shielding device in  FIG. 4  is generally the same as in  FIG. 3 . The only difference is in that the area of the grounding component  204  is enlarged, covering the connecting edge of the first portion  208  (see  FIG. 3 ) and the grounding device  212 . A larger covering area enables the shielding plate  206  to provide a better shielding effect. A better shielding effect is obtained when the area of the first portion  208  is larger than the LCD driver  114 . 
     FIG. 5  shows the structure on the back of the shielding device  202  in  FIG. 3 . The first portion  208  and the grounding component  204  are electrically connected for a better ground shielding effect of the shielding device  202 . 
     FIG. 6  depicts another embodiment of the invention. The structure of the shielding device  600  in  FIG. 6  is generally the same as the shielding device  202  in  FIG. 3 . The difference is in that the grounding component  204  of  FIG. 3  is replaced by several grounding points  602   a ,  602   b , . . . ,  602   j . The grounding points  602   a ,  602   b , . . . ,  602   j  enable the electrical connection between the first portion  606  of the shielding device  600  and the grounding device  212 . The span d between the grounding points  602   a ,  602   b , . . . ,  602   j  is preferably smaller than the threshold of the shielding effectiveness. The shielding effectiveness is defined as follows:
   SE=R+A+B (in  dB ) 
where SE is the shielding effectiveness, R is the reflection loss, A is the absorption loss, and B is the conditional correction factor. The threshold of the shielding effectiveness is computed as follows:
 The threshold of the shielding effectiveness=λ/20, 
where λ is the wavelength of the EM wave to be shielded. The span d between the grounding points  602   a ,  602   b , . . . ,  602   j  is preferably smaller than 0.625 cm, if the antenna  214  operates in the frequency band of 802.11 b/g where the frequency and the wavelength are about 2.4 GHz and 12.5 cm respectively.
 
   The invention has at least the following advantages, wherein each embodiment has one or many of the advantages. The disclosed shielding device can prevent the antenna signals of a notebook computer from interference. The disclosed shielding device can prevent the high frequency components of a display driver from interference. The invention provides a notebook computer that can prevent its antenna signals from interference. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.