| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an intercom system which allows continuous communication, securement of high security, and acquisition of satisfactory user-friendliness even in premises including an area wherein use of radio is prohibited or restricted. <P>SOLUTION: In an LED illumination part 3 connected to a master unit 4, an LED 305 for visible light and a visible light transmission section 304, and a PD 301 for infrared light and an infrared reception section 302 are installed. In a slave unit 1, an infrared transmission section 101 and a visible light reception part 102 are installed. In a head set 2 connected to the slave unit 1, an LED 201 for infrared light and a PD 202 for visible light are arranged. In the space transmission portion between the master unit 4 and slave units 1, an analog signal is FM-modulated. <P>COPYRIGHT: (C)2010,JPO&INPIT |
