Patent ID: 7860455

Claim:
An electric field communications system, comprising: a transmitter apparatus, comprising: a transmitter main electrode provided in a location so as to exert readily an electric effect on a dielectric; a transmitter return electrode; a signal generator that generates a transmission signal; and a modulator that modulates a voltage difference between said transmitter main electrode and said transmitter return electrode in response to said transmission signal; a receiver apparatus, comprising: a receiver main electrode provided in a location where said receiver main electrode is subjected readily to an electric effect from said dielectric; a receiver return electrode that establishes an electrostatic coupling with said transmitter return electrode; a measuring part that measures an electric status generated between said receiver main electrode and said receiver return electrode; and a demodulator that acquires an electric signal based on a measurement result by said measuring part and acquires said transmission signal by demodulation of the electric signal, wherein said measuring part comprises: an electro-optical crystal that exhibits a Pockels Effect and modulates light penetrating said electro-optical crystal in response to an electric field in a space where said electro-optical crystal is located; light emitting means that emits light to said electro-optical crystal; light receiving means that receives light penetrating said electro-optical crystal, and outputs signals in response to the received light; and at least one of a return electrode electrically connected to said receiver return electrode and positioned nearer said electro-optical crystal than said receiver return electrode, and a destination electrode electrically connected to said receiver main electrode and positioned nearer said electro-optical crystal than said receiver main electrode.