INTERFACE CIRCUIT AND MAIN DEVICE

WIPO Patent Application WO/2012/096027

A1

A port of a main device having a telephone exchange function is provided with an interface circuit to which a telephone or intercom can be connected. The interface circuit is provided with: a feed circuit for supplying required power supply voltage in accordance with a telephone or intercom connected to the port; and a state detection circuit which, if a telephone is connected to the port, detects whether the telephone is in an on-hook state or an off-hook state on the basis of the value of the input impedance of the telephone, and if an intercom is connected to the port, detects whether the intercom is in a standby state or a state in which the activation button is pressed on the basis of the value of the input impedance of the intercom.

ITOH, Toshihiko (2-6-1 Kitamikata, Takatsu-ku, Kawasaki-sh, Kanagawa 11, 〒2138511, JP)
伊藤　聡彦 (〒11 神奈川県川崎市高津区北見方２丁目６番１号　ＮＥＣインフロンティア株式会社内 Kanagawa, 〒2138511, JP)

JP2011/070020

July 19, 2012

September 02, 2011

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NEC INFRONTIA CORPORATION (2-6-1, Kitamikata Takatsu-ku, Kawasaki-sh, Kanagawa 11, 〒2138511, JP)
ＮＥＣインフロンティア株式会社 (〒11 神奈川県川崎市高津区北見方２丁目６番１号 Kanagawa, 〒2138511, JP)
ITOH, Toshihiko (2-6-1 Kitamikata, Takatsu-ku, Kawasaki-sh, Kanagawa 11, 〒2138511, JP)

H04Q3/58; H04M9/00; H04Q3/42

MIYAZAKI, Teruo et al. (8th Floor, 16th Kowa Bldg. 9-20, Akasaka 1-chome, Minato-k, Tokyo 52, 〒1070052, JP)

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