Abstract: The reader/writer of this invention includes a high voltage withstanding amplifier, plural resonance circuits and plural high voltage withstanding analog switching circuits. The high voltage withstanding amplifier amplifies an analog signal to be sent to the outside. Each of the resonance circuits sends the analog signal amplified by the high voltage withstanding amplifier to the outside. The high voltage withstanding analog switching circuits are provided between the high voltage withstanding amplifier and the resonance circuits correspondingly to the resonance circuits. Each of the high voltage withstanding analog switching circuits electrically connects/disconnects the high voltage withstanding amplifier to/from the corresponding resonance circuit. Since the reader/writer includes the high voltage withstanding analog switching circuits, there is no need to provide high voltage withstanding amplifiers at the previous stages of the resonance circuits as in a conventional reader/writer.

Abstract: A non-contact data carrier includes a battery, an electric-supply circuit for rectifying a received carrier signal and generating power, and an electric-supply switching circuit for comparing the voltage of the battery and the voltage generated by the electric-supply circuit and selecting either one of the voltages. When the battery can supply power, long-distance communication can be performed by supplying power from the battery. In case of battery exhaustion, power is supplied from the electric-supply circuit which receives a stronger carrier signal by using the non-contact IC card in the proximity of a question unit and rectifies the carrier signal, so that the function of the non-contact data carrier is maintained.

Abstract: The reader/writer of this invention includes a high voltage withstanding amplifier, plural resonance circuits and plural high voltage withstanding analog switching circuits. The high voltage withstanding amplifier amplifies an analog signal to be sent to the outside. Each of the resonance circuits sends the analog signal amplified by the high voltage withstanding amplifier to the outside. The high voltage withstanding analog switching circuits are provided between the high voltage withstanding amplifier and the resonance circuits correspondingly to the resonance circuits. Each of the high voltage withstanding analog switching circuits electrically connects/disconnects the high voltage withstanding amplifier to/from the corresponding resonance circuit. Since the reader/writer includes the high voltage withstanding analog switching circuits, there is no need to provide high voltage withstanding amplifiers at the previous stages of the resonance circuits as in a conventional reader/writer.

Abstract: The present invention is directed to a home automation system, wherein a coaxial cable or other home bus path for data transmission is placed inside a home to connect an intercom unit and monitor camera, which comprise a hardware interface for communication with visitors, and a conventional home television to this bus, thereby to make it possible to output the audio and video signals from the intercom unit and monitor camera on a conventional broadcast reception television.

Abstract: The present invention is directed to a home automation system, wherein a coaxial cable or other home bus path for data transmission is placed inside a home to connect an intercom unit and monitor camera, which comprise a hardware interface for communication with visitors, and a conventional home television to this bus, thereby to make it possible to output the audio and video signals from the intercom unit and monitor camera on a conventional broadcast reception television.