Object position detector

• US 5,648,642 A
• Filed: 10/25/1994
• Issued: 07/15/1997
• Est. Priority Date: 06/08/1992
• Status: Expired due to Term

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Miller, Robert J., Bisset, Stephen J.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Kim, Kevin
• Application Number:
  US08/329,809
• Time in Patent Office: 994 Days
• Field of Search: 324/690, 178/18, 178/19, 178/20, 345/173, 345/174, 345/175, 345/176, 345/177, 345/178, 341/33, 341/34
• US Class Current: 178/18.06
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A proximity sensor system includes a sensor matrix array having a characteristic capacitance between horizontal and vertical conductors connected to sensor pads. The capacitance changes as a function of the proximity of an object or objects to the sensor matrix. The change in capacitance of each node in both the X and Y directions of the matrix due to the approach of an object is converted to a set of voltages in the X and Y directions. These voltages are processed by analog circuitry to develop electrical signals representative of the centroid of the profile of the object, i.e, its position in the X and Y dimensions. The profile of position may also be integrated to provide Z-axis (pressure) information.

Claims

1. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a matrix of rows and columns on a substrate;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every second one of said sensor pads in one of said rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said columns, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said columns which are not contacted by said row conductive lines;

means for placing a step voltage onto each of said row conductive lines one at a time, and for simultaneously sensing the charge injected onto each of said column conductive lines in response to said step voltage placed onto each of said row conductive lines and for producing a set of object-sensed electrical signals related thereto.

2. The object proximity sensor of claim 1 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

3. The object proximity sensor of claim 1, further including:

means for sensing a no-object-present capacitance of each of said row conductive lines and for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

4. The object proximity sensor of claim 3 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines comprises means for computing weighted minima of said object-sensed electrical signals thereof.

5. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions such that said sensor pads form a repetitive diamond pattern;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting through said substrate the ones of said sensor pads in one of said offset column positions;

means for placing a step voltage onto each of said row conductive lines one at a time, and for simultaneously sensing the charge injected onto each of said column conductive lines in response to said step voltage placed onto each of said row conductive lines and for producing a set of object-sensed electrical signals related thereto.

6. The object proximity sensor of claim 5 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

7. The object proximity sensor of claim 5, further including:

means for sensing a no-object-present capacitance of each of said row conductive lines and for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

8. The object proximity sensor of claim 7 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines comprises means for computing weighted minimums of said object-sensed electrical signals thereof.

9. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions and said rows spaced apart such that said sensor pads form a closely packed repetitive pattern wherein each pad is not in contact with adjoining pads;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said offset column positions;

means for placing a step voltage onto each of said row conductive lines one at a time, and for simultaneously sensing the charge injected onto each of said column conductive lines in response to said step voltage placed onto each of said row conductive lines and for producing a set of object-sensed electrical signals related thereto.

10. The object proximity sensor of claim 9 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

11. The object proximity sensor of claim 9, further including:

means for sensing a no-object-present capacitance of each of said row conductive lines and for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

12. The object proximity sensor of claim 11 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines comprises means for computing weighted minimums of said object-sensed electrical signals thereof.

13. A method for providing an electrical signal representative of the position of an object in a two dimensional plane, including the steps of:

providing a sensing plane including a matrix of conductive lines arranged as a plurality of spaced apart row conductive lines and column conductive lines, said sensing plane characterized by an inherent capacitance between the various ones of said row conductive lines and said column conductive lines, said capacitance varying with the proximity of an object to said row conductive lines and said column conductive lines;

placing a step voltage onto each of said row conductive lines one at a time, and simultaneously sensing the charge injected onto each of said column conductive lines in response to said step voltage placed onto each of said row conductive lines;

producing a set of object-sensed electrical signals related to said charge injected onto each of said column conductive lines as a result of placing said step voltage on each of said row conductive lines.

38. The method of claim 13, further including the steps of:

sensing a no-object-present mutual capacitance between each individual one of said row conductive lines and each of said column conductive lines, and producing a set of no-object-present electrical signals related thereto; and

subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

14. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a matrix of rows and columns on a substrate;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every second one of said sensor pads in one of said rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said columns, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said columns which are not contacted by said row conductive lines;

means for placing a step voltage onto each of said row conductive lines one at a time;

a plurality of sense amplifiers, each of said sense amplifiers having an input connected to a different one of said column conductive lines and an output;

a plurality of sample/hold circuits, each of said sample/hold circuits having a data input connected to the output of a different one of said sense amplifiers, a control input, and an output; and

means for simultaneously placing a sample signal on the control inputs of all of said sample/hold circuits in response to said step voltage placed onto each of said row conductive lines to produce a set of object-sensed electrical signals related thereto at the outputs of said sample/hold circuits.

15. The object proximity sensor of claim 14 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

16. The object proximity sensor of claim 14, further including:

means for sensing a no-object-present capacitance between each individual one of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

17. The object proximity sensor of claim 16 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minima of said object-sensed electrical signals thereof.

18. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions such that said sensor pads form a repetitive diamond pattern;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting through said substrate the ones of said sensor pads in one of said offset column positions;

means for placing a step voltage onto each of said row conductive lines one at a time;

a plurality of sense amplifiers, each of said sense amplifiers having an input connected to a different one of said column conductive lines and an output;

a plurality of sample/hold circuits, each of said sample/hold circuits having a data input connected to the output of a different one of said sense amplifiers, a control input, and an output; and

means for simultaneously placing a sample signal on the control inputs of all of said sample/hold circuits in response to said step voltage placed onto each of said row conductive lines to produce a set of object-sensed electrical signals related thereto at the outputs of said sample/hold circuits.

19. The object proximity sensor of claim 18 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

20. The object proximity sensor of claim 18, further including:

means for sensing a no-object-present capacitance between each, individual one of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

21. The object proximity sensor of claim 20 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minimums of said object-sensed electrical signals thereof.

22. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions and said rows spaced apart such that said sensor pads form a closely packed repetitive pattern wherein each pad is not in contact with adjoining pads;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said offset column positions;

means for placing a step voltage onto each of said row conductive lines one at a time;

a plurality of sense amplifiers, each of said sense amplifiers having an input and an output, the inputs of said sense amplifiers each connected to a different one of said column conductive lines;

a plurality of sample/hold circuits, each of said sample/hold circuits having a data input connected to the output of a different one of said sense amplifiers, a control input, and an output; and

means for simultaneously placing a sample signal on the control inputs of all of said sample/hold circuits in response to said step voltage placed onto each of said row conductive lines to produce a set of object-sensed electrical signals related thereto at the outputs of said sample/hold circuits.

23. The object proximity sensor of claim 22 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

24. The object proximity sensor of claim 22, further including:

means for sensing a no-object-present capacitance between each individual one of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

25. The object proximity sensor of claim 24 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minimums of said object-sensed electrical signals thereof.

26. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a matrix of rows and columns on a substrate;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every second one of said sensor pads in one of said rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said columns, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said columns which are not contacted by said row conductive lines;

means for selecting individual ones of said row conductive lines one at a time and for simultaneously sensing the mutual capacitance between the selected one of said row conductive lines and each of said plurality of column conductive lines and for producing a set of object-sensed electrical signals related thereto.

27. The object proximity sensor of claim 26 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

28. The object proximity sensor of claim 26, further including:

means for sensing a no-object-present capacitance between each individual one of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

29. The object proximity sensor of claim 28 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minima of said object-sensed electrical signals thereof.

30. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions such that said sensor pads form a repetitive diamond pattern;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting through said substrate the ones of said sensor pads in one of said offset column positions;

means for selecting individual ones of said row conductive lines one at a time and for simultaneously sensing the mutual capacitance between the selected one of said row conductive lines and all of said plurality of column conductive lines and for producing a set of object-sensed electrical signals related thereto.

31. The object proximity sensor of claim 30 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

32. The object proximity sensor of claim 30, further including:

means for sensing a no-object-present capacitance between each individual one of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

33. The object proximity sensor of claim 32 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minima of said object-sensed electrical signals thereof.

34. An object proximity sensor, including:

a plurality of spaced-apart conductive sensor pads disposed in a plurality of rows on a substrate, the ones of said sensor pads in odd numbered ones of said rows disposed along a first set of column positions and the ones of said sensor pads in even numbered ones of said rows disposed at a second set of column positions offset from said first set of column positions and said rows spaced apart such that said sensor pads form a closely packed repetitive pattern wherein each pad is not in contact with adjoining pads;

a plurality of row conductive lines disposed on said substrate and generally aligned with said rows, each of said row conductive lines electrically contacting every one of said sensor pads in one of said odd-numbered rows;

a plurality of column conductive lines disposed on said substrate, insulated from said row conductive lines and generally aligned with said offset column positions, each of said column conductive lines electrically contacting the ones of said sensor pads in one of said offset column positions;

means for selecting individual ones of said row conductive lines one at a time and for simultaneously sensing the mutual capacitance between the selected one of said row conductive lines and each of said plurality of column conductive lines and for producing a set of object-sensed electrical signals related thereto.

35. The object proximity sensor of claim 34 wherein said row conductive lines are disposed on said first face of said substrate and said column conductive lines are disposed on a second face of said substrate opposite said first face.

36. The object proximity sensor of claim 34, further including:

means for sensing a no-object-present capacitance between each of said row conductive lines and each of said column conductive lines, for producing a set of no-object-present electrical signals related thereto; and

means for subtracting said set of no-object-present electrical signals from said set of object-sensed electrical signals.

37. The object proximity sensor of claim 36 wherein said means for producing a set of no-object-present electrical signals related to said no-object-present capacitance of each of said row conductive lines and said no-object-present capacitance of each of said column conductive lines comprises means for computing weighted minima of said object-sensed electrical signals thereof.