Patent 7230577 was granted and assigned to Omron on June, 2007 by the United States Patent and Trademark Office.
A wireless terminal position detecting device for a portable device includes a plural n-number of transmission antennas disposed such that a portion of their reachable areas overlap, a signal dividing device for dividing a request signal into the plural n-number of divided parts, and a signal distributing device for causing the divided parts of the request signal to be transmitted sequentially from these transmission antennas. The position of the portable device is detected based on an answer signal returned from the portable device in response to the request signal.