N-shaped antenna loops of digitizer tablet for reducing antenna switches and the method for locating the cordless pen

An antenna loop arrangement for a digitizer tablet, comprising:

• a plurality of physical antenna loops distributed in the digitizer tablet, said plurality of physical antenna loops separated from each other by a predetermined distance, wherein each said physical antenna loop has a first terminal and a second terminal, and a sequence for any one said antenna loop is different from sequences for two said antenna loops adjacent to said any one said antenna;
• a plurality of n-shaped logical sections for each said antenna loop, wherein second distances between any adjacent two of said n-shaped logical sections within one said antenna loop are different, and wherein said plurality of n-shaped logical sections and the adjacent n-shaped logical sections thereof belong to different physical antenna loops from each other;
• a plurality of antenna switches, each antenna switch coupled with said first terminal of said antenna loop, wherein said plurality of antenna switches are coupled with a central processing unit in the digitizer tablet;
• and
• a loop arrangement table in said central processing unit, wherein the distribution of said plurality of physical antenna loops are arranged in accordance with said loop arrangement table.

A method of arranging antenna loops of a digitizer tablet to reduce a number of antenna switches, comprising the steps of:

• providing a loop arrangement table in a central processing unit of the digitizer tablet;
• distributing a plurality of physical antenna loops in the digitizer tablet and separating said plurality of physical antenna loops with a predetermined distance from each other according to said loop arrangement table wherein said loop arrangement table comprises a table of adjacent physical antenna loops which individually disposes each physical antenna loop at the first position of each logic address, and said plurality of physical antenna loops at the first positions of said plurality of logic addresses are different from each other;
• forming a plurality of logical sections in at least one physical antenna loop and forming at least one logical section in said each antenna loop, wherein said plurality of logical sections and the adjacent logical sections thereof belong to different physical antenna loops from each other;
• coupling each said physical antenna loop with an antenna switch;
• and
• coupling said plurality of antenna switches with said central processing unit to control switching of said plurality of physical antenna loops and said plurality of logical sections thereof.

A method of locating cordless pen on a digitizer tablet, comprising:

• providing a plurality of physical antenna loops that have a plurality of n-shaped logical sections thereof, wherein said plurality of physical antenna loops are distributed in the digitizer tablet according to a loop arrangement table with a plurality of logic addresses in a central processing unit of the digitizer tablet, wherein said loop arrangement table comprises a table of adjacent physical antenna loops which individually disposes each physical antenna loop at a first position of each logic address, and said plurality of physical antenna loops at the first positions of said plurality of logic addresses are different from each other;
• causing said central processing unit to turn on a plurality of antenna switches of said plurality of physical antenna loops in order to detect a plurality of signals induced by the cordless pen;
• transmitting said plurality of signals to said central processing unit to determine a first signal, a second signal and a third signal;
• and
• locating the position of the cordless pen by a first signal, a second signal and a third signal according to said loop arrangement table of said central processing unit.