Abstract:
A keyless entry system comprising a transmitter for transmitting binary pulse signals including a specific identification code by the operation of the user, a receiver for receiving said signals from the transmitter via an antenna, and a controlling section for supplying output signals for making the action intended by said user implemented when said identification code received by said receiver and the register code stored in the storage section are determined to be identified is provided. The ground of the receiving section and the ground of the controlling section are electrically connected.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a keyless entry system mounted, for example, on the four-wheel vehicle (hereinafter referred to as vehicle). 
   2. Description of the Related Art 
   A wireless keyless entry system using a feeble electric current intended for use in the vehicle is already put into actual use. It is constructed in such a manner that a signal including the identification code supplied from the transmitter provided as a portable electronic key (remote controller) by the operation of the user such as a driver is received by the receiver via an antenna, and when the identification code is determined to be correct, the action intended by said user, such as the open/close operation of the door lock, is controlled. 
   In many cases, the receiver in such a system is disposed in the trunk room or in the dashboard, and the antenna is installed on the rear glass or the upper portion of the dashboard remote from the receiver. Therefore, the wiring connecting the antenna and the receiver requires a shielding process in order to prevent external noise that may enter from the environment, whereby the cost may be increased. 
   As a measure to solve this problem, a structure having a receiver integrated within the combination meter mounted in front of the driver&#39;s seat, and an antenna is mounted on the meter board or in the meter housing is disclosed in the Japanese Patent Laid-Open No.8-216735. In this arrangement, the shielding process is eliminated and the number of the component may be reduced, thereby realizing reduction of the cost. 
   However, in this system, the high receiving sensitivity is required as a matter of course. Though the most effective measure to realize the high receiving sensitivity is upsizing of the antenna, it has been difficult to realize since mounting of the antenna on the combination meter is physically limited due to the size of the meter. 
   SUMMARY OF THE INVENTION 
   With such a problem in view, it is an object of the present invention to provide a keyless entry system in which the antenna is mounted on the combination meter while improving the receiving sensitivity. 
   The keyless entry system according to the first aspect of the invention comprises a transmitter  200  for transmitting binary pulse signals including a specific identification code by the operation of the user, a receiver  130  for receiving said signals from the transmitter  200  via an antenna  131 , and a controlling section  140  for supplying output signals for making the action intended by said user implemented when said identification code received by said receiver  130  and the registered code stored in the storage section are determined to be identical, wherein the sensitivity of the antenna  131  is improved by electrically connecting a ground  134   a  of the receiving section  130  and a ground  149   a  of the controlling section  140 . 
   The keyless entry system according to the second aspect of the invention comprises a transmitter  200  for transmitting binary pulse signals including a specific identification code by the operation of the user, a receiver  130  for receiving said signals from the transmitter  200  via an antenna  131 , and a controlling section  140  for supplying output signals for making the action intended by said user implemented when said identification code received by said receiver  130  and the registered code stored in the storage section are determined to be identical, wherein the sensitivity of the antenna  131  is improved by forming said receiving section  130  in a unit that is attachable and detachable with respect to the controlling section  140  and forming connecting portions  133 ,  145  in the receiving section  130  and the controlling section  140  respectively for electrically connecting the ground  134   a  of the receiving section  130  and the ground  149   a  of the controlling section  140  by mounting the receiving section  130  on the controlling section  140 . Especially, it is realized in a simple structure just by providing connecting portions  133  and  145  including at least two conductive terminals and connecting at least one of them to the ground  134   a  and  149   a.    
   The keyless entry system according to the third aspect of the invention comprises a transmitter  200  for transmitting binary pulse signals including a specific identification code by the operation of the user, a receiver  130  for integrally or externally mounted to the combination meter mounted in front of the driver&#39;s seat of the vehicle so as to receive said signals from the transmitter  200  via the antenna  131 , is a controlling section  140  integrally mounted on said meter for controlling said meter and supplying output signals for making the action intended by said user implemented when said identification code received by said receiver  130  and the registered code stored in the storage section are determined to be identical, wherein the sensitivity of the antenna  131  can be improved by electrically connecting the ground  134   a  of the receiving section  130  and the ground  149   a  of the controlling section  140 . 
   The keyless entry system according to the fourth aspect of the invention comprises a transmitter  200  for transmitting binary pulse signals including a specific identification code by the operation of the user, a receiver  130  for integrally or externally mounted to the combination meter mounted in front of the driver&#39;s seat of the vehicle so as to receive said signals from the transmitter  200  via the antenna  131 , and a controlling section  140  integrally mounted on said meter for controlling said meter and supplying output signals for making the action intended by said user implemented when said identification code received by said receiver  130  and the registered code stored in the storage section are determined to be identical, wherein the sensitivity of the antenna  131  is improved by forming said receiving section  130  in a unit that is attachable and detachable with respect to said meter and forming connecting portions  133 ,  145  in the receiving section  130  and the controlling section  140  respectively for electrically connecting the ground  134   a  of the receiving section  130  and the ground  149   a  of the controlling section  140  by mounting the receiving section  130  on said meter. Especially, it is realized in a simple structure just by providing connecting portions  133  and  145  including at least two conductive terminals and connecting at least one of them to the ground  134   a  and  149   a.   

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing the structure of an embodiment of the present invention; 
       FIG. 2  is a block diagram showing the main portion of the embodiment of  FIG. 1 ; 
       FIG. 3  is a block diagram showing a state in which the embodiment of  FIG. 1 , and  FIG. 2  is in use; 
       FIG. 4  is a diagrammatic sketch explaining the relation between the receiving unit and the control unit of the same embodiment; and 
       FIG. 5  is a diagrammatic sketch explaining the relation between the receiving unit and the control unit of the same embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, the present invention will now be described. 
     FIG. 1  to  FIG. 5  show an instrument apparatus  100  for the vehicle (combination meter) to be installed in front of the driver according to an embodiment of the present invention, wherein the main unit comprises a display unit  110  for providing visual displays according to various states of the vehicle, an audio unit  120  for providing acoustic displays according to said various states of the vehicle, and a receiving unit  130  for supplying signals for controlling the vehicle in response to radio information from the outside. 
   The display unit  110  is intended for indication of various information on the vehicle as shown in  FIG. 2 , and comprises, for example, at least one instrument body  111  of cross coil type or stepping motor type for indicating a driving speed, the number of revolution of the engine, and the quantity of residual fuel by the angular degrees of the needle, a drive circuit  112  provided in association with the instrument body  111  for supplying signals to drive the instrument body  111 , a displaying element  113  such as LCD, EL, or EC for displaying the travel distance or the distance from the point to point by digital numbers or an analogue bar, a drive circuit  114  provided in association with the display element  113  for supplying signals to drive the display element  113 , a lamp for illuminating various indicators such as a direction indicator, a light illumination indicator, or a seat belt wearing state indicator, a display element  115  such as LED, and a drive circuit  116  provided in association with the display element  115  for supplying signals to drive the display element  115 . 
   The alarm unit  120  is intended for giving the driver a prescribed alarm as needed according to the state of the vehicle as shown in  FIG. 2 , and comprises, for example, a sounding element  121  such as a buzzer that gives an alarm sound by the operation of the driver or by the output of the sensors installed at adequate locations as needed, and a drive circuit  122  provided in association with the sounding element  121  for supplying signals to drive the sounding element  121 . The sounding element  121  may be mounted independently, or in association with a loudspeaker (not shown) that is installed at other location of the vehicle. 
   The receiving unit (receiver)  130  is intended for making the control unit described later perform a prescribed process in response to radio information from the outside as shown in  FIG. 2 , and comprises, for example, an antenna  131  for receiving radio wave signals from the remote controller (transmitter)  200  for the keyless entry system, and a receiving section  132  connected to the antenna  131  for subjecting said signals processes such as noise elimination process or a waveform shaping process and supplying said processed signal. 
   The reference numeral  140  denotes a control unit for controlling the respective main units  110  to  130  and the electrical equipment unit installed at each location of the vehicle described later, and comprises a control element  141  such as a microcomputer and a communication interface  142  for communicating control information with the control element  141  and receiving the output from the sensors installed at an adequate locations of the vehicle. 
   The respective main units  110  to  140  are detachably connected by the connecting means  117 ,  123 ,  133 ,  143 ,  144 ,  145  such as connectors. The controlling unit  140  comprises a connecting means  146  such as a connector to be connected to a multiplex communication line described below and a connecting means  147  to be connected to the communication line (not shown) other than said multiple communication line, and a connecting means  148  to be connected to the power source line, not shown. The components such as circuits relating to the connecting means  147 ,  148  in the controlling unit  140  are not shown. 
   In this embodiment, a display unit  110 , an alarm unit  120 , a receiving unit  130 , and a controlling unit  140  are disposed at the location where the conventional combination meter is situated, and other electric equipments provided in the vehicle, not shown, are controlled concentrically by the controlling unit  140 . In other words, as shown in  FIG. 3 , the instrument apparatus for the vehicle  100  is connected to the multiplex communication line  300  running throughout the vehicle via the connecting means  146 . 
   The door module installed on each door (electric equipment unit)  400  comprises an actuator (electric equipment)  401  for locking or unlocking the door lock, a driving unit  402  for controlling the actuator  401 , a communication interface  403  for controlling the actuator  401  via the driving unit  402  according to the instruction from the controlling element  141  of the meter driving device  100 , and a switch  404  for locking and unlocking the door lock and moving the window up and down, and is connected to the multiplex communication line (signal path)  300  via the connecting means  405  such as a connector. 
   Control of the door lock in this structure is carried out as follows. In other words, the receiving unit  130  in the instrument apparatus for the vehicle  100  receives door open/close information from the remote controller  200 . Then the controlling element  141  of the controlling unit  140  reads information received by the receiving unit  130 , and, to be specific, when the identification code received at the receiver  130  and the registered code stored in the storage section (provided in the controlling unit  140  and may be integrated with the controlling element  141 ) are determined to be identical, the result or the instruction is transmitted to each door module  400  via the multiplex communication line  300  so that the door module  400  drives the actuator  401  by the driving unit  402 . The door module  400  mounted on each door can lock and unlock the door lock or move the window up and down independently by the switch  404 . The door module  400  mounted on the door at the driver&#39;s seat can lock and unlock the door lock move the window up and down at the driver&#39;s seat by driving the actuator  401  by the driving unit  402 , and in addition, it is capable of transmitting the operating signals from the switch  404  to the control unit  140  via the multiplex communication line  300 , and reading them at the control element  141 , then transmitting the result to each door module  400  to lock and unlock the door lock or to move the window up and down at each location. 
   As shown in  FIG. 4 , the receiving unit  130  and the control unit  140  are formed respectively on the independent substrates  134  and  149 , and both substrates are physically connected by the connector (connecting portion)  133 ,  145 , and the points of grounding potentials  134   a ,  149   a  of both substrates  134 ,  149  (GND; ground) are electrically connected. To be more concrete, as shown in  FIG. 5 , the substrate  134  of the receiving unit  130  and the substrate  149  of the controlling unit  140  may be connected perpendicularly ( FIG. 5A ) or in parallel (FIG.  5 B), which may be selected according to the relation with the shape of the combination meter. Therefore, although the connectors  133 ,  145  as connecting portions have at least two conductive terminals respectively (not shown), since it is essential only that at least one of said two conductive terminals  133   a ,  145   a  is respectively connected to the ground  134   a ,  149   a , the structure may be prevented from being complicated. 
   In this structure, the substrate  134  serves as a bottom board of the antenna  131  so that the grounds  134   a  and  149   a  of the grounded substrates  134 ,  149  exhibit the mirror effect to form an imaginary antenna of electric image aside from the antenna  131 , whereby the same effect as the case where the antenna  131  is upsized is exerted, thereby increasing the benefit of the antenna  131 . 
   In order to ensure the sufficient effect and efficiency, it is desired that the grounds  134   a ,  149   a  have large areas respectively, for example by forming both substrates  134 ,  149  by multilayer substrates respectively so that the respective one of those layers are used as grounds  134   a ,  149   a . 
   According to the present invention, the receiving unit (receiver) is integrated in the combination meter mounted on the surface in front of the driver&#39;s seat and an antenna is provided in the receiving unit, so that the number of components is reduced and the shielding process is eliminated, whereby the cost reduction is realized. 
   Since the receiving unit and the controlling unit for controlling the same is formed on the independent substrates respectively, and the points of grounding potentials on those substrates electrically connected, the same effect as the case where the antenna is upsized is exerted and thus the benefit on the antenna is increased, whereby the receiving sensitivity is improved.