Touch detection for a digitizer

• US 7,372,455 B2
• Filed: 01/15/2004
• Issued: 05/13/2008
• Est. Priority Date: 02/10/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: N-Trig Ltd (Microsoft Corporation)
• Inventors: Perski, Haim, Morag, Meir
• Primary Examiner(s): Patel; Nitin
• Application Number:
  US10/757,489
• Publication Number:
  US 20040155871A1
• Time in Patent Office: 1,580 Days
• Field of Search: 345/156, 345157-176, 345/862, 345/177, 349/12, 349/174, 178/19.03, 178/18, 178/19, 178/18.07, 178/19.07, 331/65, 340/407.1, 341/5, 70/37
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/02 Input arrangements using manually operated switches, e.g. using keyboards or dials
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• 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 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• 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
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

A detector for detecting touches by fingers or like body parts on a sensor comprises at least one sensing conductor, typically a grid of such conductors, extending into the sensor, a source of oscillating electrical energy at a predetermined frequency, and detection circuitry for detecting a capacitive influence on the sensing conductor when said oscillating electrical energy is applied, the capacitive influence being interpreted as a touch. The detector is advantageous in that the same sensing conductors can be used both for touch sensing and for detection of an electromagnetic stylus.

Claims

1. A detector for providing position detection of a first kind together with position detection of a second kind, the detector comprising:

a sensor,

a patterned arrangement of sensing conductors extending within said sensor, and

detection circuitry associated with said arrangement for detecting signals at same sensing conductors arising from said position detection of a first kind and signals arising from said position detection of a second kind, therefrom to detect positions at said sensor,

wherein said position detection of a second kind comprises capacitive-based touch detection.

2. The detector of claim 1, wherein said position detection of a first kind comprises electromagnetic-based object detection of an object able to produce an electromagnetic field.

3. The detector of claim 2, wherein said sensor is located over a detection region, and comprises at least one oscillator for providing an oscillating signal to said sensing conductors and to an excitation circuitry for providing an excitation signal capable of exciting an electromagnetic stylus-type object, wherein said patterned arrangement extends over said detection region, and wherein said detection circuitry is adapted for detecting the capacitive effect of a conductive object, such as finger touch, and signals from said stylus-type object at least one of the sensing conductors.

4. The detector of claim 3, wherein said electromagnetic-based object comprises a resonance circuit, and said excitation signal is adapted to excite said resonance circuit.

5. The detector of claim 3, wherein said detection region is the surface of a display screen and wherein said sensor including said conducting conductors is substantially transparent.

6. The detector of claim 3, wherein said sensing circuitry is configured for sensing a signal at least one of the sensing conductors induced by a touch of a conductive object subjected to a transmission of said oscillated signal.

7. The detector of claim 3, wherein there is provided at least a second sensing conductor located within said sensor and having a junction with said one conductive element, wherein said oscillator is applied to the at least one of the sensing conductors said detector being configured to detect a resulting oscillating signal at said sensing conductor, wherein said resulting signal is caused by a touch of a conductive object at said junction, and therefrom to infer said touch.

8. The detector of claim 7, wherein said detection circuitry is adapted to detect a signal at said at least second sensing conductor for interpretation as a number of touching objects.

9. The detector of claim 3, wherein said oscillator is connected to oscillate at least one of said detector, part of said detector and the at least one sensing conductor with respect to a reference voltage level, thereby to permit a capacitive current flow between a conductive touching object and said at least one sensing conductor.

10. The detector of claim 2, wherein multiple electromagnetic-based objects can be detected based on the interpretation of properties of the detected signal.

11. The detector of claim 1, wherein said detection circuitry is capable of detecting interactions of said first kind and said interactions of said second kind simultaneously.

12. The detector of claim 1, wherein said detection circuitry is capable of detecting interactions of said first kind and said interactions of said second kind independently.

13. The detector of claim 1, wherein said sensor is substantially transparent and suitable for location over a display screen.

14. The detector of claim 1, wherein said detection circuitry comprises a differential detector arrangement associated with said sensing conductors for detecting differences between outputs of said conductors.

15. The detector of claim 1, wherein said sensor is configured with a transparent medium between itself and an underlying display screen.

16. The detector of claim 15, wherein said transparent medium comprises an air gap.

17. The detector of claim 1, wherein said detection circuitry comprises a differential detector arrangement associated with said sensing conductors for detecting differences between outputs of said conductors.

18. The detector of claim 1, configured to interpret a property of a signal detected at said at least one sensing conductor in terms of a number of touching conductive objects.

19. The detector of claim 1, wherein said sensor is configured with a transparent medium between itself and said display screen.

20. The detector of claim 19, wherein said transparent medium comprises an air gap.

21. The detector of claim 1, wherein said sensor comprises a grid of sensing conductors arranged within a layer thereof.

22. The detector of claim 21, wherein said sensing conductors are connected pairwise to amplifiers.

23. The detector of claim 22, wherein said amplifiers are differential amplifiers each having a positive input and a negative input and wherein one sensing conductor of said pair is connected to said positive input and a second sensing conductor of said pair is connected to said negative input.

24. The detector of claim 23, further comprising a compensation table for providing a compensation value at each differential amplifier'"'"'s output resulting from difference of the input capacitance values at each of said differential amplifier'"'"'s inputs.

25. The detector of claim 1, wherein said detector comprises

a source of an oscillating electrical signal at a predetermined frequency, and

detecting circuitry for detecting a capacitive influence on said at least one sensing conductor when said oscillating electrical signal is applied.

26. The detector of claim 25, wherein said source of oscillating electrical signal is configured to transmit said signal into a conductive object, and said sensing circuitry is configured for sensing a signal at said at least one sensing conductor induced by a touch of said conductive object subjected to said transmitted oscillated signal.

27. The detector of claim 25, wherein there is provided at least a second sensing conductor located within said sensor and having a junction with said at least one sensing conductor, wherein said source of oscillating electrical signal is applied to one of said conductors, said detector being configured to detect a resulting oscillating signal at said second sensing conductor, wherein said resulting oscillating signal is caused by a touch of a conductive object at said junction, and to infer said touch.

28. The detector of claim 27, wherein said detection circuitry is configured to interpret a property of a detected signal as a number of touches of a corresponding conductor.

29. The detector of claim 27, comprising a matrix of first sensors aligned in a first direction and second sensors aligned in a second direction with a plurality of junctions in between, and further comprising a tabulation of leakage signals caused by capacitance values for each junction, said detector being configured to use said leakage signal values to correct readings at each conductor.

30. The detector of claim 25, wherein said source of oscillating electrical signal is connected to oscillate at least one of said detector, part of said detector and said at least one sensing conductor with respect to a reference voltage level, thereby to permit a capacitive current flow between a conductive object and said at least one sensing conductor.

31. The detector of claim 30, wherein said source of oscillating signal is connected to oscillate a first part of said detector, and wherein said first part is connected to a second part not subject to oscillations via a communication connection unaffected by the potential difference between said first and said second parts of the detector.

32. The detector of claim 31, wherein said communication connection comprises at least one differential amplifier.

33. The detector of claim 25, further comprising a compensation table for providing a compensation value at each conductor to compensate for leakage signal resulting from parasitic capacitance value.

34. The detector of claim 33 or claim 24, configured to update said compensation table upon system startup.

35. The detector of claim 33 or claim 24, configured to use ambiguous object detection as a trigger to refresh said compensation table.

36. The detector of claim 35, wherein any combination of number, phase and position data from detected signals are used to define ambiguity in object detection.

37. The detector of claim 25, wherein said oscillating signal to an external transmitter to energize a touching capacitive object.

38. The detector of claim 25, wherein said detector comprises a matrix of a first set of conductors aligned in a first direction and a second set of conductors aligned in a second direction, said oscillating signal is provided to said first set of conductors and sensed at any of said second set of conductors to which said signal has been passed by a capacitive link caused by a touching conductive object.

39. The detector of claim 25, wherein said oscillating signal to at least one of said sensing conductors such that a conductive object drains current from a respective conductor.

40. The detector of claim 39, comprising using said oscillating signal to oscillate a detection mechanism comprising said conductors wherein said oscillated detection mechanism is simultaneously isolated from common ground.

41. The detector of claim 39, comprising:

using said oscillating signal to oscillate a first part of a detection mechanism, said first part comprising said sensing conductors,

isolating said first part from a second part, and

using said isolated second part to communicate touch detection outputs to external devices.

42. The detector according to any of claims 7 or 25-33, wherein said conductive object is a body part.