Coordinate detecting method

• US 4,758,690 A
• Filed: 03/03/1987
• Issued: 07/19/1988
• Est. Priority Date: 07/12/1986
• Status: Expired due to Term

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Kimura, Kiyoshi
• Primary Examiner(s): SCHREYER, STAFFORD
• Application Number:
  US07/021,148
• Time in Patent Office: 504 Days
• Field of Search: 178/18, 178/19, 364/520
• US Class Current: 178/18.01
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A coordinate detecting method, adapted to a coordinate input device comprising an input plane having a plurality of parallel embedded loops, establishes a plurality of coarse regions while taking as a reference the polarity reversing positions of a magnetic field detected when these loops are scanned in sequence. The method comprises the steps of specifying one coarse region to be interpolated, interpolating the designation position of a coordinate designating member within the specified coarse region, and calculating the coordinate of the designation position on the basis of the coordinate position of the specified coarse region and an interpolation value obtained in the interpolating step.

Claims

1. A coordinate detecting method comprising the steps of:

establishing coordinate positions of a plurality of coarse regions while taking as a reference the polarity reversing positions of a magnetic field detected when a scan signal is sent to scan an input plane equipped with a plurality of main loops made of parallel embedded conductors such that the main loops are driven in sequence by the scan signal;

specifying one coarse region, in which a coordinate designating member is located, to be interpolated;

interpolating a designated position of the coordinate designating member located within the specified coarse region; and

calculating the coordinate of the designated position on the input plane designated by the coordinate designating member on the basis of the coordinate position of the specified coarse region and an interpolation value obtained in the interpolating step,

wherein the coordinate position of the specified coarse region is obtained by accessing a ROM table storing therein a deviation amount (O_n, n=an integer) between the coordinate position of each loop (L_n) and the coordinate position of a start point of the corresponding coarse region (S_n) so as to obtain a pertinent deviation amount, and by adding it to the coordinate position of the corresponding loop (L_n).

2. A coordinate detecting method according to claim 1, wherein each coarse region (S_n, n=an integer) is established as starting at the point where a detection voltage (V_n) owing to the corresponding loop (L_n) is zero and ending at the point where a detection voltage (V_n+2) owing to the loop (L_n+2) succeeding but one to that loop (L_n) is zero.

3. A coordinate detecting method according to claim 2, wherein the coarse region to be interpolated is determined as S_n if |V_n+2 /V_n+1 |≧

1 when the magnetic field polarity detected by the coordinate designating member reverses for the first time upon scanning the loop L_n+2, otherwise is determined as S_n+1, where V_n+2 and V_n+1 are the detection voltages owing to loops L_n+2 and L_n+1, respectively.

4. A coordinate detecting method according to claim 2, wherein the interpolation value X_p pertinent to the coarse region S_n specified is calculated in accordance with either of the following equations:

##EQU7## and ##EQU8## where V_n and V_n+2 are the detection voltages owing to loops L_n and L_n+2, respectively.