Touch detection for a digitizer

• US 7,843,439 B2
• Filed: 03/26/2007
• Issued: 11/30/2010
• 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:
  US11/727,301
• Publication Number:
  US 20070171211A1
• Time in Patent Office: 1,345 Days
• Field of Search: 345156-173, 178/18.01
• 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 of at least one object on a transparent sensor located over a display screen, the detector comprising. a display screen; a patterned arrangement of conductors extending into said sensor situated over said display screen; and detection circuitry adapted to detect capacitive coupling of said at least one object with said at least one conductor.

Claims

1. A method of touch detection at a matrix of conductors located in a transparent sensor, the matrix of conductors including a first and a second sets of conductors forming a grid with a plurality of junctions at which the conductors do not contact, the method comprising:

providing an oscillating signal to conductors from the first set of conductors, and

detecting said oscillation signal when transferred via said junctions to said conductors from second set of conductors, said transference being indicative of capacitive effects on said conductors due to touch of an object on the sensor at a respective junction.

2. The method according to claim 1, comprising distinguishing more than one touch interaction with the sensor at the same time based on output detected from second set of conductors.

3. The method according to claim 1, comprising determining an amount of parasitic current transfer for each junction and subtracting the amount from output detected on the second set of conductors.

4. The method according to claim 1, comprising:

determining a tabulation of leakage capacitance values for each junction;

correcting output detected from the second set of conductors based on the leakage capacitance values.

5. The method according to claim 1, comprising providing the oscillating signal to one conductor line at a time from the first set of conductors, and detecting output in response to each oscillating signal provided on the first set of conductors, from a plurality of conductors from the second set of conductor lines.

6. The method of claim 1, wherein junctions respective of locations of more than one object relative to the transparent sensor are determined simultaneously.

7. Touch detection apparatus comprising:

a transparent sensor comprising a grid array of conductors in a first direction and conductors in a second direction, having plurality of junctions at which the conductors do not contact; and

an oscillator capable of providing an oscillation signal to conductors in said first direction,

detection circuitry adapted to detect said oscillation signal when transferred via said junctions to conductors in said second direction, said transference being indicative of capacitive coupling induced by a touch of an object touching said sensor at a respective junction.

8. The apparatus of claim 7, further comprising a tabulation of leakage signals caused by capacitance values for each junction, said apparatus being configured to use said leakage signals values to correct readings at each conductor.

9. The apparatus of claim 8, configured to update said tabulation upon system startup.

10. The apparatus of claim 8, configured to update said tabulation during system operation.

11. The apparatus of claim 7, wherein said apparatus is configured to detect an object that is a body part.

12. The apparatus of claim 7, further configured to determine the position of said touches relative to said sensor.

13. The apparatus of claim 7, wherein said detection circuitry further configured to use interpolation to increase measurement accuracy.

14. The apparatus of claim 7, wherein said sensor is an integral part of a display screen.

15. The apparatus of claim 7, wherein said sensor is an accessory situated over a display screen.

16. The apparatus of claim 7, wherein the detection circuitry is operative to determine positions of more than one object relative to the sensor.

17. The apparatus of claim 16, wherein the positions of the more than one object relative to the sensor are determined simultaneously.

18. The apparatus of claim 7, wherein the conductors in the first direction and the conductors in the second direction are arranged within at least one layer thereof.

19. The apparatus according to claim 7, wherein the sensor is constructed from at least one transparent foil patterned with at least a portion of the conductors.

20. The apparatus according to claim 7 wherein the sensor is constructed from a first layer formed with the conductors in the first direction and a second layer formed with the conductors in the second direction.

21. The apparatus according to claim 20, wherein the first and second layer are electrically isolated from each other.

22. The apparatus according to claim 7, wherein the detection circuitry is operable to determine an amount of parasitic current transfer for each junction and subtract the amount from the outputs detected.

23. The apparatus according to claim 7, wherein the oscillator is operable to initiate applying the signal oscillation to one conductor at a time from the conductors in the first direction, and said detection circuitry is operable to detect output in response to each oscillation signal applied from a plurality of conductors in the second direction.

24. The apparatus according to claim 7, wherein the conductors from each of the first or second directions are parallel to each other.

25. The apparatus according to claim 7, wherein the object is a finger.

26. A multi-touch detection apparatus comprising:

a sensor including a first and second set of conductor lines forming a grid with a plurality of junctions therebetween;

circuitry operative to apply signals to conductor lines from one of the first or second set of conductor lines;

circuitry operative to detect outputs from conductor lines from the other set of conductor lines in response to a signal applied to at least one conductor line, wherein each of said outputs is indicative of a level of capacitive coupling formed between the at least one conductor line on which a signal is applied and conductor lines on which output is detected; and

a detector operative to distinguish between more than one finger touch at the same time based on the outputs,

wherein the sensor is substantially transparent and suitable for positioning over an electronic display.

27. The apparatus according to claim 26, wherein the detector is operative to select one of the first or second set of conductors for receiving signals applied by the circuitry and the other set of conductors from which outputs are detected.

28. A method for multi-touch detection, the method comprising:

providing a sensor including a first and second set of conductor lines forming a grid with a plurality of junctions therebetween,

applying a signal to at least one conductor line from the first set of conductor lines;

detecting outputs from conductor lines from the second set of conductor lines in response to the applied signal, wherein each of the outputs is responsive to a level of capacitive coupling formed between the at least one conductor line from the first set and a conductor line from the second set; and

distinguishing more than one finger touch interacting with the sensor at the same time based on the outputs,

wherein a detection area of the sensor is substantially transparent so as to be suitable for positioning over an electronic display.

29. The method according to claim 28 comprising applying a signal to one conductor line at a time from one of the first or second set of conductor lines, and detecting output in response to each signal applied from a plurality of conductor lines from the other set of conductor lines.