Abstract:
The fixation of a coaxial cable between a GPS receiver and a receiver antenna mounted in a vehicle to an earthing conductor allows the elimination of influences due to noise and the improvement of reception even if the GPS antenna and the receiver antenna are mounted on the same mounting board due to reduction in the size of the device.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a receiver such as, for example, a GPS receiver comprising a GPS antenna which acts as a receiving antenna and a GPS receiver module which acts as a receiving module. 
     BACKGROUND TO THE INVENTION 
     This type of GPS receiver is mounted in an automobile, receives a GPS signal from a satellite and detects an automobile position. In order to reduce the size of the device, the GPS receiver module and the GPS antenna are for example positioned in proximity on a mounting board of the vehicle dashboard for example. 
     However as discussed above, when the size of the device is reduced by positioning the GPS receiver module and the GPS antenna in proximity on the mounting board of the vehicle dashboard, noise is easily transmitted from the GPS receiver module to the GPS antenna and reception is lowered. 
     The present invention is proposed to solve the above problem and has as its purpose the removal of noise with a simple structure and the improvement of reception. 
     DISCLOSURE OF THE INVENTION 
     The receiver of the present invention comprises an earthed mounting board which positions a receiver module and a receiver antenna, a coaxial cable which connects said receiver module and said receiver antenna and an earthing conductor which fixes said coaxial cable to said mounting board. 
     This type of receiver allows noise, which are high frequencies which result from condenser action due to the coaxial cable shield and the casing, being directed to the earthing through the mounting board which is earthed to the earthing conductor. Thus reception is improved. 
     The receiver of the present invention is characterized by the use of a earthing conductor as a conductor which runs through the coaxial cable. This type of receiver does not need a designated earthing conductor and thus allows the number of components to be reduced and the layout to be simplified. 
     The receiver of the present invention is characterized in that an earthing conductor is comprised of solder which mounts a coaxial cable shield layer on a mounting board. This type of receiver allows the mounting of the coaxial cable to be strengthened and at the same time allows accurate laying of the earthing connection. 
     The receiver of the present invention is characterized in that one end of the earthing conductor is fixed to the receiver module and the free end is press fitted to the connector of the mounting board of the coaxial cable. This type of receiver allows noise which is generated by the coaxial cable to be directed to the earthing through the earthing conductor and allows improved reception. 
     The earthing conductor of the receiver of the present invention is characterized in that one end is fixed to the mounting board and the free end press fits the coaxial cable to the connector of the mounting board. This type of receiver allows noise which is generated by the coaxial cable to be directed to the earthing through the earthing conductor and allows improved reception as well as accurately maintaining the connection by maintaining the pressure on the connecting end on the connector. 
     The earthing conductor of the receiver of the present invention is characterized in that the earthing conductor is a cut off piece. This type of receiver allows for the earthing connection of the coaxial cable totally without the need for another member by the cut off piece provided on the mounting board. This allows for a simple cost effective structure. This also allows the noise from the coaxial cable to be directed to the earthing through the conductor and improved reception. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a plan figure of embodiment 1 of the present invention. 
     FIG. 2 is a lateral cross section along line A—A of FIG.  1 . FIG. 3 is a perspective figure showing the tubular conductor used in embodiment 1 of the present invention. 
     FIG. 4 is a side view of the component parts showing embodiment  2  of the present invention. 
     FIG. 5 is a perspective view of the components parts showing embodiment 3 of the present invention. 
     FIG. 6 is a perspective view of the components parts showing embodiment 4 of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention are explained in detail below with reference to the accompanying figures. 
     Embodiment 1 
     FIG. 1 is a figure showing embodiment  1  of the present invention. In the figure, reference numeral  1  denotes an earthed mounting board,  2  is a GPS receiver module which is fixed and mounted on the mounting board  1 ,  3  is a GPS antenna (receiver antenna) which is fixed to the mounting board in proximity to the GPS receiver module,  4  is a coaxial cable which connects the GPS receiver module  2  and the GPS antenna  3 ,  5  is a conductor which is coiled part way along the coaxial cable  4  (earthing conductor),  6  is solder or a mounting screw of the conductor  5  on the mounting board  1 . FIG. 2 is a lateral cross sectional enlargement along line A—A in FIG.  1 . 
     The operation of the invention will be explained below. 
     Signals as well as high frequency noise is transmitted to the central conductor  4   a  of the coaxial cable. The noise is transmitted through the shield layer  4   c.  In this case, the coaxial cable  4  has a shield layer  4   c  provided on the outer peripheral surface of the insulation layer  4   b  which covers the central conductor  4   a.  An insulation maintenance layer  4   d  is provided on the outer peripheral face of the shield layer  4   c.  This insulation maintenance layer  4   d  is sandwiched by the conductor  5  and the shield layer  4   c  and acts as a condenser. The high frequency noise which is transmitted to the shield layer  4   c  is transmitted to the conductor  5 , flows onto the earthing and is eliminated. As a result, it is possible to reduce noise transmitted to the GPS antenna  3  and to improve reception. 
     A tubular conductor (the example shown) which runs through the coaxial cable  4 , conductive foil which is coiled onto the coaxial cable  4 , solder or the like may be used as the conductor  5 . However as shown in FIG. 3, this may be in the form of providing a mounting piece  5   b  which projects laterally to the tubular conductor  5   a  which runs through the coaxial cable  4 . It is also possible to fix a tubular conductor  5   a  running through the coaxial cable  4  to the mounting board  1  by the mounting piece  5   b.    
     As shown above, according to embodiment 1, it is possible to direct noise generated along the coaxial cable  4  to the earthing through the conductor  5  by earthing and fixing the coaxial cable  4  along the GPS receiver module  2  and the GPS antenna  3  by the conductor  5  on the earthed mounting piece  5   b.  Thus it is possible to improve reception. 
     Embodiment 2 
     FIG. 4 shows a second embodiment of the present invention. In the figure, reference numeral  7  denotes a connector which is provided on the mounting board,  8  is a connecting terminal with respect to the connector  7  mounted on the end of the coaxial cable  4 ,  9  is a conductor (earthing conductor) one end of which is mounted by a screw  10  on the housing of the GPS receiver module  2  mounted on the mounting board  1 . The free end of the conductor, which bends in a U shape and projects downwardly, presses on the upper surface of the connecting terminal  8 . The connector  7  and the electrical circuit (not shown) in the interior of the GPS receiver module  2  are connected through a circuit (not shown) provided on the mounting board  1 . 
     The operation of the invention will be explained below. 
     In a second embodiment of the invention, since the outer surface of the connecting terminal  8  is earthed through a housing of the conductor  9 —GPS receiver module  2 , as stated in embodiment 1 above, the insulation maintenance layer  4 d is sandwiched between the coaxial cable  4  and the shield layer  4   c  and acts as a condenser. Thus the high frequency noise which is transmitted through the shield layer  4   c  is transmitted to the housing from the conductor  9 , flows onto the earthing and is eliminated. 
     As shown above, according to embodiment 2 of the present invention, a connecting terminal  8  provided on the end of the coaxial cable  4  is connected to the connector  7 . It is possible to eliminate noise in the coaxial cable by directing it to the earthing through the conductor  9  by maintaining the pressing connection of the connecting terminal  8  on the connecting terminal on the connector side with a conductor  9  one end of which is mounted with a screw  10  on the housing of the GPS receiver module  2 . Thus reception can be improved and the connection of the connecting terminal  8  can be maintained on the connector  7 . 
     Embodiment 3 
     FIG. 5 shows embodiment 3 of the present invention. In the figure,  12  is a cut off piece provided on the mounting board  1 . The cut off piece  12  acts as an earthing conductor running through the coaxial cable  4  between the mounting board  1 . 
     As shown above, according to embodiment 3, it is possible to earth and connect the coaxial cable  4  totally without using a separate part. It is further possible to direct the noise which is transmitted to the coaxial cable  4  through the mounting board  1  by a simple and cost effective structure and to improve reception. 
     Embodiment 4 
     FIG. 6 shows embodiment 4 of the present invention. In the figure,  13  is solder which directly solders the shield layer  4   c  , which exposes and partially strips the insulating maintenance layer  4   d  of the outer surface of the coaxial cable  4 , to the earthed mounting board  1 . 
     As shown above, according to embodiment 4, it is possible to strengthen the mounting of the coaxial cable  4  by a soldered connection of the shield layer  4   c  of the coaxial cable  4  to the directly connected mounting board  1 . At the same time, it is possible to accurately perform the earthing connection and to improve reception. 
     Each embodiment shows the GPS receiver module  2  and the GPS antenna  3  placed in proximity on the same mounting board  1 . However even when the GPS receiver module  2  and the GPS antenna  3  are mounted independently on different mounting boards  1 , the same effect is achieved in both embodiments due to earthing the coaxial cable  4  which connects both through a conductor  5 . 
     INDUSTRIAL APPLICABILITY 
     as shown above, the receiver of the present invention eliminates high frequency noise and improves reception, even when a gps receiver and an antenna are placed in proximity, by fixing a coaxial cable between the gps receiver and an antenna mounted in the vehicle.