Electric Field Sensor Device, Transceiver, Positional Information Obtaining System, and Information Input System

Abstract

When a human hand ( 100 ) holds a transceiver ( 3 a ), the hand holds a bottom of an external wall surface and a side of the external wall surface of an insulating case ( 33 ). Therefore, a transmitting and receiving electrode ( 105 ) and an insulating film ( 107 ) cover not only the bottom of the external wall surface but also the side of the external wall surface of the insulating case ( 33 ). A first ground electrode ( 131 ), a second ground electrode ( 161 ), and a third ground electrode ( 163 ) are attached to upper portions of the internal wall surface of the insulating case ( 33 ) apart from the transmitting and receiving electrode ( 105 ). An insulating foam member ( 7 a ) is interposed between the insulating case ( 33 ) and a transceiver main body ( 30 ), and an insulating foam member ( 7 b ) is interposed between the transceiver main body ( 30 ) and a battery ( 6 ).

1 . An information input system comprising:
 electric field inducing means that is contacted or operated by an electric field transmission medium, and induces an electric field in said electric field transmission medium according to a physical quantity based on the contact or operation;   a transceiver that receives the electric field induced in said electric field transmission medium, applies the electric field to a polarization modulator or an optical intensity modulator, polarization-modulates or optical intensity-modulates laser light according to the electric field, converts the polarization-modulated or optical intensity-modulated laser light into an electric signal, extracts an electric signal having a frequency component concerning a physical quantity based on said contact or operation from the converted electric signals, and outputs the electric signal concerning the physical quantity based on said contact or operation; and   information processing means for inputting therein the electric signal concerning the physical quantity based on said contact or operation from said transceiver, and obtaining information corresponding to the physical quantity based on said contact or operation by said electric field transmission medium.   
   
   
       2 . An electric field sensor device that modulates optical intensity of laser light based on an electric field to be detected, thereby detecting said electric field, said electric field sensor device having an electric field sensor unit and a light receiving circuit, wherein said electric field sensor unit includes:
 laser light emitting means;   branching means for branching a laser light emitted from said laser light emitting means into a first laser light and a second laser light that are different from each other; and   optical intensity modulating means with which said electric field to be detected is coupled, that modulates the optical intensity of said first laser light based on said coupled electric field, and   said light receiving circuit includes:
 first light/voltage converting means for converting the optical intensity of said first laser light modulated by said optical intensity modulating means into a voltage signal; 
 second light/voltage converting means for converting the optical intensity of said second laser light branched by said branching means into a voltage signal; and 
 differential amplifying means for differentially amplifying the voltage signal obtained by conversion by said first light/voltage converting means and the voltage signal obtained by conversion by said second light/voltage converting means. 
   
   
   
       3 . The electric field sensor device according to  claim 2 , wherein said electric field sensor unit further includes an optical variable attenuator that attenuates the optical intensity of said second laser light obtained by branching by said branching means, and said second photoelectrical converting means inputs said second laser light attenuated by said optical variable attenuator. 
   
   
       4 . The electric field sensor device according to  claim 2 , wherein said electric field sensor unit further includes a first optical variable attenuator that attenuates the optical intensity of said first laser light obtained by branching by said branching means at a predetermined rate, and a second optical variable attenuator that attenuates the optical intensity of said second laser light obtained by branching by said branching means at a rate higher than an attenuation rate of said first optical variable attenuator, said optical intensity modulating means inputs therein said first laser light attenuated by said first optical variable attenuator, and said second photoelectrical converting means inputs therein said second laser light attenuated by said second optical variable attenuator. 
   
   
       5 . The electric field sensor device according to  claim 2 , wherein
 said first light/voltage converting means includes:
 first light/current converting means for converting the optical intensity of said first laser light modulated by said optical intensity modulating means into a current signal; 
 a first voltage source that applies an inverse bias voltage to said first light/current converting means; and 
 a first load resistor that converts said current signal obtained by conversion by said first light/current converting means into a voltage signal, and 
   said second light/voltage converting means includes:
 second light/current converting means for converting the intensity of said second laser light obtained by branching by said branching means into a current signal; 
 a second voltage source that applies an inverse bias voltage to said second light/current converting means; and 
 a second load resistor that converts said current signal obtained by conversion by said second light/current converting means into a voltage signal. 
   
   
   
       6 . The electric field sensor device according to  claim 5 , wherein at least one of said first load resistor and said second load resistor is a variable resistor. 
   
   
       7 . The electric field sensor device according to  claim 5 , wherein at least one of said first voltage source and said second voltage source is a variable voltage source. 
   
   
       8 . The electric field sensor device according to  claim 2 , wherein said light receiving circuit further includes amplifying means for amplifying at least one of the voltage signal obtained by conversion by said first light/voltage converting means and the voltage signal obtained by conversion by said second light/voltage converting means. 
   
   
       9 . A transceiver that receives information based on an electric field induced in an electric field transmission medium, thereby receiving the information via said electric field transmission medium, said transceiver comprising:
 said electric field sensor device according to  claim 2 ;   a signal processing circuit that at least removes a noise from a voltage signal output from said electric field sensor device;   noise detecting means for detecting quantity of a noise component of the voltage signal output from said signal processing circuit; and   a control signal generator that generates a control signal to variably control a variable value of said electric field sensor unit or said light receiving circuit based on the detection data output from said noise detecting means.