Position resolving system

• US 5,225,637 A
• Filed: 10/01/1991
• Issued: 07/06/1993
• Est. Priority Date: 10/01/1991
• Status: Expired due to Term

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Kurta Corp. (Mutoh Holdings Company Limited)
• Inventors: Rodgers, James L., Fowler, Billy C., Gray, Donald F.
• Primary Examiner(s): Schreyer, Stafford
• Application Number:
  US07/769,447
• Time in Patent Office: 644 Days
• Field of Search: 178/19, 178/18, 178/20, 340/706
• US Class Current: 178/19.03
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A position resolving system is described incorporating a cordless pointing instrument such as a pen having an oscillator and battery supply therein. Electromagnetic radiations from the pen are directed onto a tablet grid having a plurality of grid loops therein. When the pen is in contact with the tablet, signals of maximum amplitude are radiated; when the pen is raised out of contact with the tablet, signal radiation is maintained but at a decreased amplitude for a predetermined time and then reduced to zero. Each loop is formed of parallel conductors joined at one end thereof by an end conductor; each loop is placed adjacent corresponding loops in the X and in the Y directions. The electromagnetic radiations are non-coherently amplitude detected to select the grid loop in the X direction and the grid loop in the Y direction having the maximum amplitudes thereon. When an X loop and a Y loop are detected each of which have signal amplitudes thereon that are higher than the remaining X and Y loops, and wherein the signal amplitudes are above a predetermined threshold amplitude, the system subsequently scans selected loops in the vicinity of the max loops in accordance with automatically selected routines. The routines are selected in accordance with criteria that include pen speed, signal strength and pen location. The routines may either rely upon the signal strength on a subset of three grid loops in each of the X and Y directions or a subset of four grid loops in the X and Y directions.

Claims

1. In a position resolving system for resolving the position of a radiating instrument relative to a tablet surface, the improvement comprising:

(a) a tablet having a plurality of X and Y conductors arranged orthogonally with respect to each other;

(b) a radiating instrument for radiating an electromagnetic signal at a first amplitude, from said instrument to said tablet; and

(c) said instrument including a switch therein responsive to instrument contact with said tablet surface for increasing the amplitude of the signal radiated by said instrument to a second amplitude to indicate a pen down condition.

2. The combination set forth in claim 1 wherein said radiating instrument is cordless and includes an oscillator and a power supply therein for driving said oscillator to radiate said electromagnetic signal at a predetermined frequency and at a first amplitude.

3. A position resolving system for resolving the position of a radiating instrument relative to a tablet surface comprising:

(a) a tablet having a plurality of X and Y conductors arranged orthogonally with respect to each other;

(b) a radiating instrument for radiating an electromagnetic signal at a predetermined frequency, and at a first amplitude, from said instrument to said tablet;

(c) said instrument including a switch therein responsive to instrument contact with said tablet surface for increasing the amplitude of the signal radiated by said instrument to a second amplitude to indicate a pen down condition;

(d) means responsive to the amplitude of signals on said conductors for generating an address of estimated instrument position;

(e) means responsive to said pen down condition for generating a pen down status condition for a predetermined time; and

(f) said means for generating an address of estimated instrument position responsive to said pen down status condition for ignoring the signals sensed on said conductors for the duration of said pen down condition.

4. The combination set forth in claim 3 wherein said radiating instrument is cordless and includes an oscillator and a power supply therein for driving said oscillator to radiate said electromagnetic signal at a predetermined frequency and at a first amplitude.

5. The combination set forth in claim 3 including means for substituting data for the ignored signals.

6. The combination set forth in claim 5 wherein said substituted data comprises an average of the data received prior to the pen down condition and data received after said predetermined time.

7. A position resolving system for resolving the position of a radiating instrument relative to a tablet surface comprising:

(a) a tablet having a plurality of X and Y conductors arranged orthogonally with respect to each other;

(b) a radiating instrument for radiating an electromagnetic signal at a predetermined frequency, and at a first amplitude, from said instrument to said tablet;

(c) said instrument including a switch therein responsive to instrument contact with said tablet surface for increasing the amplitude of the signal radiated by said instrument to a second amplitude to indicate a pen down condition;

(d) a non-coherent amplitude detection means connected to said conductors for sampling signals induced therein by said radiated electromagnetic signal;

(e) means responsive to the amplitude of signals on said conductors, detected by said non-coherent amplitude detector, for generating an instrument address;

(f) means responsive to said pen down condition for generating a pen down status condition for a predetermined time sufficient to sample selected X and Y conductors near said instrument address; and

(g) said means for generating an instrument address responsive to said pen down status condition for ignoring the signals sensed on said conductors for the duration of said pen down condition.

8. The combination set forth in claim 7 including means for substituting data for the ignored signals.

9. The combination set forth in claim 8 wherein said substituted data comprises an average of the data received prior to the pen down condition and data received after said predetermined time.

10. A position resolving system for resolving the position of a radiating instrument relative to a tablet surface comprising:

(a) a tablet having a plurality of X loops and a plurality of Y loops, each loop formed by parallel spaced apart conducors interconnected by an end conductor, said X and Y loops arranged orthogonally with respect to each other;

(b) a cordless radiating instrument including an oscillator and a power supply therein for driving said oscillator to radiate an electromagnetic signal at a first amplitude, said instrument including a switch therein responsive to instrument contact with said tablet surface for increasing the amplitude of the signal radiated by said instrument to a second amplitude to indicate a pen down condition;

(c) a non-coherent amplitude detection means connected to said conductors for sampling signals induced in said loops by said radiated electromagnetic signal;

(d) means responsive to the amplitude of signals on said conductors, detected by said non-coherent amplitude detector, for generating an instrument address;

(e) means responsive to said pen down condition for generating a pen down status condition for a predetermined time sufficient to sample selected X and Y loops near said instrument address; and

(f) said means for generating an instrument address responsive to said pen down condition for ignoring the signals sensed on said conductors for the duration of said pen down condition.

11. The combination set forth in claim 10 including means for substituting data for said ignored signals.

12. The combination set forth in claim 11 wherein said substituted data comprises an average of the data received prior to the pen down condition and data received after said predetermined time.

13. In a position resolving system for estimating the position of an electromagnetic radiating instrument relative to a tablet surface, the

improvement comprising:

(a) a tablet having a plurality of X conductors and having a plurality of Y conductors arranged orthogonally with respect to said X conductors;

(b) a cordless radiating instrument having an oscillator therein for radiating an electromagnetic signal from a coil connected to said oscillator to said tablet;

(c) a non-coherent amplitude detection means connected to said conductors for sampling signals induced therein by said radiated electromagnetic signal; and

(d) means responsive to the amplitude of signals on said conductors, above a predetermined threshold amplitude, detected by said non-coherent amplitude detector means for generating an address of said instrument position.

14. The combination set forth in claim 13 wherein said radiating instrument includes a power supply therein for driving said oscillator.

15. The combination set forth in claim 14 wherein said oscillator is a current driven oscillator for radiating an electromagnetic signal having a predetermined frequency.

16. In a position resolving system for resolving the position of a radiating instrument relative to a tablet surface, the improvement

comprising:

(a) a tablet having a plurality of X loops and a plurality of Y loops, each loop formed by parallel spaced-apart conductors interconnected by an end conductor, said X and Y loops arranged orthogonally with respect to each other;

(b) a cordless radiating instrument having an oscillator therein for radiating an electromagnetic signal from said instrument to said tablet;

(c) a non-coherent amplitude detection means connected to said loops for sampling signals induced therein by said radiated electromagnetic signal; and

(d) means responsive to the amplitude of signals on said conductors, above a predetermined threshold amplitude, detected by said non-coherent amplitude detector means for generating an address of said instrument position.

17. The combination set forth in claim 16 wherein said radiating instrument incorporates a power supply therein for driving said oscillator.

18. The combination set forth in claim 17 wherein said oscillator is a current driven oscillator.

19. In an apparatus for resolving the position of a radiating instrument relative to the surface of a tablet in a direction perpendicular to a plurality of parallel conductors in said tablet, the improvement comprising:

(a) means connected to said conductors for detecting signal amplitudes on the conductors and selecting a conductor having the maximum amplitude signal thereon;

(b) means forming a difference between the amplitude of the signal on the conductor having the maximum amplitude signal thereon and the amplitude of the signal on a conductor thrice removed from said conductor having the maximum amplitude signal thereon; and

(c) means responsive to the polarity of said difference for selecting one of a first and a second routine for generating an address of said instrument position.

20. The apparatus of claim 19 including means for incrementing or decrementing the address of said instrument by two conductor positions when said first routine is selected and incrementing or decrementing the address of said instrument by one conductor position when said second routine is selected.

21. The combination set forth in claim 19 wherein said first routine includes the sampling of the amplitudes of signals on a first predetermined selected subset of conductors near said radiating instrument and said second routine includes sampling of the amplitudes of signals on a second and different predetermined selected subset of conductors near said radiating instrument.

22. In an apparatus for resolving the position of an electromagnetic radiating instrument relative to the surface of a tablet in a direction perpendicular to a plurality of parallel conductors in said tablet, the improvement comprising:

(a) means connected to said conductors for non-coherently detecting signal amplitudes on the conductors and selecting a conductor having the maximum amplitude signal thereon;

(b) means forming a difference between the amplitude of the signal on the conductor having the maximum amplitude signal thereon and the amplitude of the signal on a conductor thrice removed from said conductor having the maximum amplitude signal thereon; and

(c) means responsive to the polarity of said difference for selecting a first or a second routine for generating an address of said instrument position.

23. The apparatus of claim 22 including means for incrementing or decrementing the address of said instrument by two conductor positions when said first routine is selected and incrementing or decrementing the address of said instrument by one conductor position when said second routine is selected.

24. The combination set forth in claim 22 wherein said first routine includes the sampling of the amplitudes of signals on a first predetermined selected subset of conductors near said radiating instrument and said second routine includes sampling of the amplitudes of signals on a second and different predetermined selected subset of conductors near said radiating instrument.

25. In an apparatus for use in a position resolving system for resolving the position of an electromagnetic radiating instrument relative to the surface of a tablet having X and Y conductors therein, the improvement comprising:

(a) means connected to said conductors, for non-coherently detecting signal amplitudes on the conductors and selecting the X conductor and the Y conductor having the maximum amplitude signals thereon;

(b) means forming a difference between the amplitudes of the signals on the X conductor having the maximum amplitude signal thereon and the amplitude signal on the conductor thrice removed from said X conductor with maximum amplitude signal thereon;

(c) means responsive to the polarity of said difference for selecting a first or a second routine for resolving the X position of said instrument;

(d) means for forming a difference between the amplitudes of signals on the Y conductor having the maximum amplitude signal thereon and the amplitude signal on the Y conductor thrice removed from said conductor with a maximum amplitude thereon; and

(e) means responsive to the polarity of said difference for selecting one of a first and a second routine for resolving the Y position of said instrument.

26. The apparatus of claim 25 including means for incrementing or decrementing the address of the estimated position of said instrument by two conductor positions when said first routine is selected and incrementing or decrementing the estimated position of the instrument by one conductor position when said second routine is selected.

27. The apparatus of claim 25 wherein said first routine includes the sampling of the amplitude of signals on a predetermined selected subset of conductors near said instrument and said second routine includes the sampling of the amplitude of signals on a second and different predetermined selected subset of conductors near said instrument.

28. For use in a position resolving system for resolving the position of an electromagnetic radiating instrument relative to the surface of a tablet having a plurality of parallel conductors therein, the improvement comprising:

(a) means, connected to said conductors, for non-coherently detecting signal amplitude on the conductors and selecting the conductor having the maximum signal thereon;

(b) means responsive to said selection for forming a first difference between the amplitudes of signals on conductors next to but on opposite sides of said conductor with the maximum amplitude;

(c) means responsive to said first difference for forming a second difference between amplitudes of signals on one of the conductors next to said conductor with a maximum amplitude thereon and a conductor twice removed from and on the opposite side of the conductor with the maximum amplitude thereon;

(d) means responsive to said second difference for forming a third difference between the amplitude of signals on said conductor with maximum amplitude thereon and a conductor thrice removed from the conductor with the maximum amplitude thereon; and

(e) means responsive to the polarity of said third difference for selecting one of a first and a second routine for generating an address of said instrument position.

29. The apparatus of claim 28 including means for incrementing or decrementing the address of the estimated position of said instrument by two conductor positions when said first routine is selected and incrementing or decrementing the estimated position of the instrument by one conductor position when said second routine is selected.

30. The apparatus set forth in claim 28 wherein said first routine includes sampling of the amplitudes of signals on a first predetermined selected subset of conductors near said radiating instrument and said second routine includes sampling of the amplitudes of signals on a second and different predetermined selected subset of conductors near said radiating instrument.

31. For use in a position resolving system for resolving the position of an electromagnetic radiating instrument relative to the surface of a tablet having a plurality of parallel conductors therein, the improvement comprising:

(a) means, connected to said conductors, for non-coherently detecting signal amplitude on the conductors and selecting the conductor having the maximum signal thereon;

(b) means responsive to said selection for forming a first difference between the amplitudes of signals on conductors next to but on opposite sides of said conductor with the maximum amplitude;

(c) means responsive to said first difference for forming a second difference between amplitudes of signals on one of the conductors next to said conductor with a maximum amplitude thereon and a conductor twice removed from and on the opposite side of the conductor with the maximum amplitude thereon;

(d) means responsive to said second difference for forming a third difference between the amplitude of signals on said conductor with maximum amplitude thereon and a conductor thrice removed from the conductor with the maximum amplitude thereon; and

(e) means responsive to the sum of said second and third differences divided by the difference of said second and third differences for generating an estimated address of said instrument.

32. For use in a position resolving system for resolving the position of an electromagnetic radiating instrument relative to the surface of a tablet having a plurality of parallel conductors therein, the improvement comprising:

(a) means, connected to said conductors, for non-coherently detecting signal amplitude on the conductors and selecting the conductor having the maximum 10 signal thereon;

(b) means responsive to said selection for forming a first difference between the amplitudes of signals on conductors next to but on opposite sides of said conductor with the maximum amplitude;

(c) means responsive to said first difference for forming a second difference between amplitudes of signals on one of the conductors next to said conductor with a maximum amplitude thereon and a conductor twice removed from and on the opposite side of the conductor with the maximum amplitude thereon;

(d) means responsive to said second difference for forming a third difference between the amplitude of signals on said conductor with maximum amplitude thereon and a conductor thrice removed from the conductor with the maximum amplitude thereon;

(e) means forming a fourth difference between the amplitudes of the signals on said conductor with the maximum amplitude signal thereon and a conductor next to said conductor with the maximum amplitude; and

(f) means responsive to said third difference divided by said fourth difference for generating an estimated address of said instrument.

33. In an apparatus for resolving the position of a radiating instrument relative to the surface of a tablet having conductors therein, the improvement comprising:

(a) means connected to said conductors for selecting the conductor having the signal with the maximum amplitude thereon;

(b) means responsive to the selection of said conductor for forming a first difference between the amplitude of signals on a conductor next to the conductor having the maximum amplitude signal thereon and on a conductor twice removed and on the opposite side of a conductor having the maximum amplitude signal thereon;

(c) means responsive to said selection for forming a second difference between amplitudes of signals on the conductor having the maximum amplitude signal thereon and on a conductor thrice removed therefrom and on said opposite side; and

(d) means responsive to the sum of said first and second differences divided by the difference of said first and second differences for generating an estimated address of said instrument.

34. In an apparatus for resolving the position of a radiating instrument relative to the surface of a tablet having conductors therein, the improvement comprising:

(a) means connected to said conductors for selecting the conductor having the signal with the maximum amplitude thereon;

(b) means responsive to the selection of said conductor for forming a first difference between the amplitude of signals on a conductor next to and on one side of the conductor having the maximum amplitude signal thereon and on a conductor twice removed and on the opposite side of a conductor having a maximum amplitude signal thereon;

(c) means for forming a second difference between the amplitude of signals on a conductor next to but on the opposite side of the conductor having the maximum amplitude signal thereon and on a conductor twice removed and on said one side of a conductor having the maximum amplitude signal thereon; and

(d) means responsive to the sum of said first and second differences divided by the difference of said first and second differences for generating an estimated address of said instrument.

35. A method for resolving the position of a signal radiating instrument relative to the surface of a tablet having a plurality of grid conductors therein, comprising:

(a) selecting the conductor having the signal with the maximum amplitude thereon;

(b) forming a difference between the amplitude of the signal on the conductor having the maximum amplitude signal thereon and the amplitude of the signal on a conductor thrice removed from said conductor having a maximum amplitude signal thereon; and

(c) sensing the polarity of said difference for selecting one of a first routine and a second routine for generating an address of said instrument position.

36. A method for resolving the position of an electromagnetic radiating instrument relative to the surface of a table having X and Y orthogonally position conductors therein comprising:

(a) selecting the X conductor having the maximum amplitude signal of all X conductors;

(b) selecting the Y conductor having the maximum amplitude signal of all Y conductors;

(c) forming a difference between the amplitudes of the signals on the X conductor having the maximum amplitude signal thereon and the amplitude signal on the conductor thrice removed from said X conductor with the maximum amplitude signal thereon;

(d) forming a difference between the amplitudes of the signals on the Y conductor having the maximum amplitude signal thereon and the amplitude signal on the Y conductor thrice removed from said conductor with the maximum amplitude thereon;

(e) sensing the polarity of the difference between the signals on the X conductors for selecting one of a first and a second routine for generating an X address of said instrument position; and

(f) sensing the polarity of the difference between the signals on the Y conductors for selecting one of a first and a second routine for generating an Y address of said instrument position.

37. A method for resolving the position of an electromagnetic radiating instrument relative to the surface of the tablet having a plurality of parallel conductors therein, comprising:

(a) selecting the conductor having the maximum signal thereon;

(b) forming a first difference between the amplitudes of the signals on the conductors next to but on the opposite sides of the conductor with the maximum amplitude;

(c) forming a second difference between the amplitudes of the signals on one of the conductors next to said conductor with the maximum amplitude thereon and a conductor twice removed from and on the opposite side of the conductor with the maximum amplitude thereon;

(d) forming a third difference between the amplitude of signals on said conductor with the maximum amplitude thereon and a conductor thrice removed from the conductor with the maximum amplitude thereon; and

(e) sense the polarity of said third difference for selecting one of a first and a second routine for generating an address of said instrument position.

38. A method for resolving the position of a signal radiating instrument relative to the surface of the tablet having a plurality of grid conductors therein comprising:

(a) selecting the conductor having the signal with the maximum amplitude thereon;

(b) forming a first difference between the amplitude of signals on a conductor next to the conductor having the maximum amplitude signal thereon and on a conductor twice removed and on the opposite side of a conductor having the maximum amplitude signal thereon;

(c) forming a second difference between the amplitudes of signals on the conductor having the maximum amplitude signal thereon and on a conductor thrice removed therefrom and on said opposite side;

(d) forming the sum of said first and second differences;

(e) forming a difference of said first and second differences;

(f) dividing said sum by the difference of said differences for generating an estimated address of said instrument.