Abstract:
A radiation blocking device for use with a portable communication apparatus such as a cordless or cellular phone. The device has a radiation shield and a connector for attaching the shield to the apparatus. The shield is sized and shaped to reflect radiation emitted by the antenna which would otherwise strike the head of a user of the apparatus. The shield also reflects and absorbs heat emitted by the antenna, reducing the amount of such heat incident on said user&#39;s head. The shield is in the shape of an arc of circle and is preferably positioned concentrically with the antenna.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to portable phones and radios, and more particularly, the invention relates to radiation shields for blocking electro-magnetic radiation and heat emitted by the antennas of such phones and radios.  
         BACKGROUND OF THE INVENTION  
         [0002]    Portable communication devices such as portable phones, including both cellular phones and cordless phones for the home, have increased in popularity significantly in recent years. Each of these devices communicates with a base station using electro-magnetic signals. In the case of a cordless phone, the base station is usually located within 100 metres of the portable unit. In the case of a cellular phone, the base station may be a communication tower located many kilometres from the portable unit.  
           [0003]    Portable phones operate on a wide range of signal frequencies. For example, older analog cell phones typically operate at frequencies of approximately 850-900 MHz, while newer digital cell phones operate on the order of 1800 MHz, or 1.8 GHz. Cordless phones for use in the home operate at about 45 MHz, 900 MHz, and more recently, 2.4 GHz, depending on the type. Portable phones, cordless phones and other types of wireless communication devices also operate at other frequencies. In this application, we will refer to portable phones. The invention is equally applicable to other portable communication devices.  
           [0004]    An increasingly urgent concern among consumers in recent years, is that portable phones may present a health risk to a user when the phone is held close to the head when in use. This concern has sparked many studies of the health risks to portable phone users, based on the signal frequencies of the phone, and the usage characteristics, such as the distance of the portable phone from the head of the user and overall hours of usage. These health risks are believed to be greater when a higher frequency portable phone is used, as is increasingly the case.  
           [0005]    Such studies have shown that heath risks associated with radiation from portable phones may include headaches, loss of concentration, loss of memory and brain tumors. Almost all portable phones have an antenna for transmitting and receiving the electromagnetic signals which allow communication with the base station. The antenna generally extends vertically from the housing of the portable phone. Given its role in a portable phone&#39;s communication system, the antenna is one of the largest sources of radiation emitted by a portable phone.  
           [0006]    Some research has also shown that portable phone antennas also emit heat, which can cause a user&#39;s head to be warmed, especially when a portable phone is used for an extended period. This may also be associated with adverse health effects.  
           [0007]    It is therefore desirable to reduce the exposure of a portable phone user to the electro-magnetic radiation and heat emitted from a portable phone antenna. Several existing devices have been used for this purpose.  
           [0008]    U.S. Pat. No. 5,819,162 (Spann et al.) discloses a flip-up shield that mounts around the earpiece region of a portable phone. In use, the shield flips up and is positioned between the antenna and the user&#39;s head. The device is particularly intended to block radiation emitted by the antenna from striking a hearing aid worn by the user, and thereby reduces the adverse effects of the radiation on the operation of the hearing aid. This device has several disadvantages. The device is bulky and has a relatively unsightly appearance. It also requires that the user actively flip the shield into its operational position prior to each use of the portable phone. A user may forget to do so, particularly when receiving a phone call. Furthermore, the shape and size of the device are not configured to protect the user&#39;s entire head from radiation.  
           [0009]    U.S. Pat. No. 5,338,896 (Danforth) discloses a sliding planar shield for a portable phone with an antenna. The shield includes a rectangular body, an upper tab for attachment to the antenna, and two lower tabs for attachment of the shield to the phone. This device alters the appearance of the portable phone undesirably, and adds significant bulkiness to the phone, due to the shape of the shield. Furthermore, this device is useful only with portable phone antennas which may be extended. Increasingly, portable phone antennas are either non-extending (particularly in higher frequency digital phones) or may be extended optionally (in “dual mode” cellular phones, which are capable of operating at more than one frequency).  
           [0010]    U.S. Pat. No. 5,335,366 (Daniels) discloses a sleeve that completely surrounds the antenna of a portable phone, and contains a barrier layer which shields the user from radiation emitted by the antenna. The sleeve, however, reduces the communication performance of the antenna, because both incoming and outgoing signals are disrupted by the shield as well.  
           [0011]    Accordingly, there exists a need for a device that effectively shields a portable phone user from radiation emitted from the phone&#39;s antenna. Preferably, the device does not substantially interfere with the communication function of the antenna. Preferably, the device does not require the user to actively place it into the desired position each time the portable phone is to be used.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention provides a radiation blocking device which has a radiation shield and a connector. The radiation shield and connector are rigidly attached by a neck. Preferably, the entire device is formed from an integral piece of metal. The connector is formed as a cylinder with a slit or gap on one side. The connector is friction fitted onto the antenna or the base of the antenna of a portable phone. The shield is then held in a fixed position between the antenna and a user&#39;s head by the connector and the neck. The shield is shaped to block any line of sight between the antenna and the user&#39;s head, so that any electro-magnetic signal emitted by the antenna is reflected away from the user&#39;s head. The shield thus provides a three dimensional region of space in which the electro-magnetic radiation emitted by the antenna is substantially attenuated and within which the user&#39;s head will be positioned when the portable phone is in use.  
           [0013]    The shield is preferably made of metal and the preferred embodiment is formed from a single piece of a brass alloy with a nickel plating. The shield also provides a heat blocking function to reduce the effects of heat emitted from the portable phone antenna on the user. Some of the emitted heat is reflected by the shield while additional heat is absorbed and later dissipated into the ambient environment.  
           [0014]    The radiation shield is shaped as a part of a cylinder and its cross-section, in a direction perpendicular to the axis of the antenna of the portable phone, appears as an arc of a circle. Preferably, the axis of this circle is co-axial with the axis of the antenna when the device is mounted on the portable phone.  
           [0015]    Th neck of the device is angled so that the radiation shield is spaced apart from the antenna in use. A pair of tabs extend from the shield adjacent the neck to prevent radiation from passing through the gap created by the neck and striking the user&#39;s head.  
           [0016]    The radiation shield is configured to mounted on the portable phone and left in place. It thus provides automatic protection from both electro-magnetic radiation and heat emitted from the antenna without the user taking any additional steps each time he or she uses the phone.  
           [0017]    In one aspect, the present invention provides a device for blocking electro-magnetic radiation emitted by an antenna of a portable communication apparatus, the device comprising: a radiation shield having a perimeter; and a connector to mount the radiation shield on the apparatus such that, when the device is mounted to the apparatus, the radiation shield together with the antenna defines a three dimensional region in which electro-magnetic radiation emitted by the antenna is attenuated, and whereby, when said apparatus is used by a user, the region is sufficiently large to encompass a head of the user.  
           [0018]    In a second aspect, the present invention provides a radiation blocking device for use with a portable communication apparatus having an antenna, the portable communication apparatus configured to be positioned adjacent a user&#39;s head, the radiation block device comprising: a radiation shield for blocking electro-magnetic radiation emitted by the antenna; and a connector rigidly coupled to the radiation shield, the connector adapted for mounting to the portable communication apparatus such that the radiation shield is positioned between the antenna and the user&#39;s head.  
           [0019]    In a third aspect the present invention provides a device for blocking electro-magnetic radiation emitted by an antenna of a portable communication apparatus, the device comprising: means for blocking radiation, said radiation blocking means having a perimeter; and means for connecting to mount the radiation blocking means on the apparatus such that, when the device is mounted to the apparatus, the radiation blocking means together with the antenna defines a three dimensional region in which electromagnetic radiation emitted by the antenna is attenuated, and whereby, when said apparatus is used by a user, the region is sufficiently large to encompass a head of the user.  
           [0020]    In a fourth aspect the present invention provides a device for use with a portable communication apparatus having an antenna, the portable communication apparatus configured to be positioned adjacent a user&#39;s head, the device comprising: means for blocking radiation, said radiation blocking means adapted to block electro-magnetic radiation emitted by the antenna; and means for connecting rigidly coupled to the radiation blocking means, the connecting means adapted for mounting the device to the apparatus such that the radiation blocking means is positioned between the antenna and the user 3  s head.  
           [0021]    Additional aspects and characteristics of the present invention are set out below in the description of the preferred embodiments. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0022]    The present invention will now be described by way of example only, with reference to the drawings in which:  
         [0023]    [0023]FIG. 1 is an isometric view of a portable phone and a radiation blocking device in accordance with a first preferred embodiment of the present invention;  
         [0024]    [0024]FIG. 2 is a cross-sectional view of a shield of the device of claim  1 ;  
         [0025]    [0025]FIG. 3 is a cross-sectional view of a connector of the device of claim  1 ;  
         [0026]    [0026]FIG. 4 is a side view of the device of FIG. 1, mounted on a portable phone in use by a user;  
         [0027]    [0027]FIG. 5 is a magnified view of a portion of FIG. 2; and  
         [0028]    [0028]FIG. 6 is a plan view of the device of FIG. 1 mounted on a portable phone in use by a user; and  
         [0029]    [0029]FIG. 7 is a plan view of the shield of the device of claim  1  and several base stations. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    Reference is first made to FIG. 1, which illustrates a radiation blocking device  10  made in accordance with a first embodiment of the present invention. Device  10  has a radiation shield  12 , a neck  14  and a connector  16 . Neck  14  joins shield  12  and connector  16  such that they are held in a fixed position relative to one another. Shield  12  is at the top of device  10  and connector  16  is at the bottom of device  10 .  
         [0031]    [0031]FIG. 2 is a cross-sectional view of shield  12 . Shield  12  is formed as an arc of a circle, with an axis  18 . Shield  12  has a radius R c  and an included arc angle A c . FIG. 3 is a cross-sectional view of connector  16 , which is also formed as an arc of a circle, with an axis  24 . Connector  16  has a radius R s . Connector  16  has a pair of arms  25  and  26  which are separated by a gap  28 . The radius R c  of shield  12  is greater than the radius R c  of connector  16 .  
         [0032]    Referring again to FIG. 1, shield  12  has a pair of extension tabs  22  which extend downward adjacent the top of neck  12 .  
         [0033]    In use, device  10  is mounted onto a portable phone  30  (or other portable communication device), as shown in FIGS. 4, 5 and  6 . Phone  30  has an antenna housing  32 , which extends from the top of the phone&#39;s housing  34 . Typically, antenna housing  32  will have a base  34 , although this is not always the case, and is not necessary. In this example, antenna housing  32  is not extendable from its base  34 , as is typical for modern higher frequency digital cellular phones (often referred to as “PCS” phones). Antenna housing  32  contains an antenna  33 , which is coupled to the communications circuitry (not shown) of the phone  30 . Typically, housing  32  will be generally cylindrical with a diameter between 5-15 mm. Antenna  33  will typically be an elongated wire or metal cylinder and will be installed along the axis of antenna housing  32 .  
         [0034]    To install device  10  onto phone  30 , connector  16  is slid onto and frictionally engages base  34  (or antenna housing  32 ). Connector  16  holds device  10  on phone  30  such that shield  12  is positioned between the head  36  of a user and antenna  33 . Prior to installing connector  16  onto base  34 , the user  36  may open or close arms  25  and  26  to provide a larger or smaller radius R c , so that connector  16  will be able to engage base  34  with sufficient force to hold device  10  in place. Preferably, when connector  16  is installed on base  34 , the axis  18  of shield  12  is positioned co-axially with antenna  33 .  
         [0035]    When phone  30  is in use, antenna  33  will emit electro-magnetic radiation and heat. The emitted electro-magnetic radiation will propogate in all directions from antenna  33  in straight lines, including the direction of the user&#39;s head  36 .  
         [0036]    Shield  12  is positioned such that it blocks any line of sight between antenna  32  and the user&#39;s head  36  (i.e. no radiation vector emitted by antenna  33  can strike the user&#39;s head, since it will be reflected shield  12 ). When connector  16  is positioned on base  34 , the top  40  of shield  12  extends higher than the top edge  43  of antenna  12  such that a surface  42 , which is defined by the top of antenna  32  and the top edge  43  of shield  12  passes above the user&#39;s head  36 . Similarly, the bottom edge  47  of shield  12  extends below the bottom of antenna  32  so that a surface  46 , which is defined by the bottom edge  47  of antenna  33  and the bottom side of shield  12  passes below the user&#39;s head  36 . Surfaces  42  and  46  are shown in cross-section in FIGS. 4 and 5 as lines. Surfaces  42  and  46  may be complex 3-dimensional surfaces, depending on the exact shape of the top edge  43  and bottom edge  47  of shield  12 . Surfaces  42  and  46  define the limits of protection provided by shield  12  in an upward and downward direction to block radiation emitted by antenna  33  from striking the user&#39;s head  36 . One skilled in the art will recognize that neck  14  will block some radiation emitted by antenna  33 . One skilled in the art will recognize that this will not detrimentally affect the position of surface  46 , since the presence of neck  14  will simply block radiation emitted by antenna  33  from striking parts of the user&#39;s body in addition to the user&#39;s head  36 .  
         [0037]    Reference is next made to FIG. 6, which is a plan view of device  10 , phone  30  and the user&#39;s head  36  when the phone  30  is in use and the device  10  has been installed as described above. Surface  48 , which is defined by the axis  18  of shield  12  (which is preferably co-axial with antenna  33 ) and the front edge  49  of shield  12  (when viewed from the perspective of the user) passes in front of the user&#39;s head  36 . Surface  50 , which is defined by the axis  18  of shield  12  and the rear edge  51  of shield  12  passes behind the user&#39;s head  36 . Surfaces  48  and  50  are shown in FIG. 6 in cross-section as lines. Surfaces  48  and  50  define the frontward and rearward limits of protection provided by shield  12  to block radiation emitted by antenna  33  from striking the user&#39;s head  36 .  
         [0038]    Shield  12  operates by reflecting electromagnetic radiation which strikes it. Thus, electro-magnetic radiation emitted by antenna  33  that strikes shield  12  is prevented from striking an object on the opposite side of shield  12 . Collectively, surfaces  42 ,  46 ,  48  and  50  define a three dimensional region of space  52  which extends from the location of antenna  33  outward. Region  52  defines the range of protection of shield  12  and when phone  30  is in use and device  10  is properly installed, the user&#39;s head  36  will be positioned within region  52 .  
         [0039]    Radiation shield  12  is preferably, although not necessarily, spaced transversely (compared to its axis) away from antenna housing  32  by neck  14 . The presence of neck  14  can create a gap between radiation shield  12  and connector  16 . Tabs  22  extend downward from shield  12  to ensure that no radiation emitted by antenna  33  passes through the gap and strikes the user&#39;s head  36 .  
         [0040]    The shape and size of region  52  depends on (i) the shape and size of antenna  33 , (ii) the height of shield  12  between its top edge  43  and its bottom edge  47 , (iii) the included angle A s  of shield  12  between its front edge  49  and its rear edge  51  and (iv) the placement of shield  12  relative to antenna  33 . A person skilled in the art will be capable of selecting the height, included angle and placement of shield  12  to ensure that the user&#39;s head  36  is within region  52  when a selected phone  30  is in use. These criteria are selected so that there is no line of sight between the antenna  33  and the user&#39;s head  36 . The placement of shield  12  will depend on the length and angle of neck  14 , and selection of these characteristics is also within the competence of one skilled in the art.  
         [0041]    The preferred embodiment of shield  12  is formed of a brass alloy which provides a substantial attenuation of the electromagnetic radiation emitted by antenna  33 . The radiation blocking characteristics of brass and brass alloys are well understood and a person skilled in the art will be capable of selecting a suitable material. A brass alloy which provides some resilience and rigidity is preferable for the present purpose. Such an alloy will provide a less deformable device  10  and shield  12  than pure brass.  
         [0042]    Preferably, device  10  is formed from a single piece of metal. If device  10  is made from two or more parts (i.e. where shield  12 , neck  14  and connector  16  are first separately in two or three parts and then joined by welding or another method of fastening), the resulting device may be prone to weak spots at its joints, where it may break. Although such a device is not preferred by the inventor, it will still fall within the scope of the present invention.  
         [0043]    In the preferred embodiment of device  10 , it is coated with a nickel plating. This coating provides some additional reflection of electro-magnetic radiation and heat, although its function is primarily aesthetic. Device  10  may alternatively be coated with a plastic material or paing which can be colored to match the color of phone  20 . Alternatively, device  10  may not be coated or may have another coating.  
         [0044]    In addition to protection from electromagnetic radiation, shield  12  also provides the user with protection from heat emitted from antenna  33 . Heat emitted by antenna  33  is both reflected and absorbed by shield  12 . The reflected heat is reflected in a direction opposite that the of the user&#39;s head  36 , and therefore does not affect the user. Heat that is absorbed is later dissipated into the ambient environment. Although some of this dissipated heat may reach the user&#39;s head  36 , it is likely that much of the absorbed heat will be dissipated when the phone  30  and device  10  are not in use, after a phone call. In addition, device  10  may act as heat sink and may absorb some heat directly from antenna  33  or its base  34  through connector  16 . This heat will also be dissipated subsequently to the ambient environment. By these operations, a substantial amount of the heat generated by antenna  33  during a phone call will be prevented from striking the user&#39;s head  36 .  
         [0045]    Since connector  16  and neck  14  are also preferably made from the same material as radiation shield  12 , connector  16  and neck  14  may also provide radiation blocking, heat blocking and heat absorbing effects, enhancing the efficacy of device  10  is protecting the user.  
         [0046]    Reference is next made to FIG. 7. The inventor has found that the use of device  10  can increase the effectiveness of antenna  33  in transmitting and receiving electro-magnetic signals when communicating with a base station. FIG. 7 illustrates shield  12 , antenna  33  and two base stations  60 ,  62  in plan view.  
         [0047]    Typically, phone  30  (not shown in FIG. 7) will be in communication with one base station at a time. Line  64  and  66  illustrate two “rays” of the electromagnetic signal which will be transmitted by base station  60  when phone  30  is communication with it. Typically, rays  64  and  66  will contain identical information. Ray  64  is received directly by antenna  33 , as is well understood in the art. Ray  66 , however, initially passes and is not received by antenna  33 . The inventor believes that shield  12  operates to reflect ray  66  (or the energy in ray  66 ) so this is reflected into antenna  33  as shown at  66 ′ and  66 ″. In this way, shield  12  operates to focus some of the electro-magnetic signal that is transmitted by base station  60  and is incident on shield  12  on to antenna  33  and thereby increase the strength of the signal received by antenna  33 .  
         [0048]    At another time, phone  30  may be in communication with base station  62 . Lines  68  and  70  represent two rays of the electromagnetic signal transmitted by antenna  33 . Ray  68  is transmitted directly to and received by base station  62 . Ray  70  is reflected by shield  12  and re-directed as rays  70 ′ and  70 ″. Ray  70 ″ is received base station  62 . In this way, some of the electro-magnetic signal which is transmitted by antenna  33  and which is incident on shield  12  is directed to base station  62 , increasing the strength of the signal received by base station  62  from phone  30 .  
         [0049]    The present invention provides several advantages over prior art devices. The present invention allows a portable phone user to protect his or her head from the effects of electro-magnetic radiation and heat emitted by a portable phone&#39;s antenna. The present device does need to be removed between uses of the portable phone, and once affixed does not require any steps to put it into operation prior to uses of the portable phone. The present device thus provides effective and automatic protection to the user.  
         [0050]    A preferred exemplary embodiment has been described. Other embodiments of the present invention may have additional features.  
         [0051]    Depending on the degree and type of protection required from device  10 , shield  12  may not be configured to shield the entire head  36  of a user, or it may be configured to protect additional parts of the user&#39;s body (for example, the user&#39;s neck). In this case, the height and included angle of the shield will be varied so that the region  52  includes those parts of the user&#39;s body that are desired to be protected.  
         [0052]    The connector  16  of the device  10  described above had a circular cross section, with a gap  28 . Many portable phones have an antenna base or an antenna housing which is not circular. For use with these phones, the connector  16  of device  10  may be shaped to frictionally engage such an antenna base or antenna housing. Furthermore, many portable phones may also provide another means for attaching device  10 . In this case, connector  16  may be shaped to engage such means, which may include recesses in the housing of the portable phone, or frictional engagement with a portion of the housing of the portable phone or another means.  
         [0053]    The preferred embodiment described above was described in the context of an antenna  33  which has a base  34  and which does not extend from phone housing. Some portable phones do not have a base  34  for their antennas. In this case, the connector  16  may be attached directly to the antenna of the phone, and if necessary, neck  16  may be formed such that the bottom edge of shield  12  extends below the bottom edge of the connector  16 .  
         [0054]    Many portable phones have an extendible antenna. Shield  12  may be elongated between its top and bottom edges to provide protection to a user&#39;s head from the entire length of such an extendible antenna.  
         [0055]    In another embodiment of the present invention, the inner surface of the connector  16  may be coated with an adhesive or high friction material or may be formed to provide greater frictional engagement with base  34 . For example, the inner surface of connector  16  may be grooved or notched. This will produce a stronger mounting of device  10  on base  34 .  
         [0056]    The shield  12  of device  10  has been illustrated in the Figures with rounded corners. In another embodiment, the shield  12  may have square corners.  
         [0057]    A preferred embodiment of the present invention and several variations of it have been described. Other variations of the invention are possible, and each of these fall within the spirit and scope of the invention, which is limited only by the appended claims.