Method for multiple objects detection on a capacitive touchpad

• US 7,701,447 B2
• Filed: 01/19/2006
• Issued: 04/20/2010
• Est. Priority Date: 06/08/2005
• Status: Active Grant

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: Chien, Yung-Lieh, Lii, Jia-Yih
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Abdin; Shaheda A
• Application Number:
  US11/334,444
• Publication Number:
  US 20070165005A1
• Time in Patent Office: 1,552 Days
• Field of Search: 345/173, 345/156, 345/174, 715/856, 178 1801- 1903
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A multiple objects detection method for a capacitive touchpad, through at least one preset time, whether it is noise and interference or an operation of object on touchpad is thus distinguished, actions such as object touches the touchpad, leaves the touchpad are then judged correctly, and different kinds of gesture operations are precisely detected.

Claims

1. A multiple objects detection method for capacitive touchpad, comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when the first peak value and the second peak value are all greater than a threshold value;

wherein if the sensed value remains greater than the threshold value within a preset time, T_DownDetect, and remains a continuously increasing trend during said preset time, T_DownDetect, wherein such signifies that at least two objects are touching the touchpad.

2. The multiple objects detection method of claim 1, further comprising:

calculating the object number on the touchpad;

calculating the touching time of the at least two objects touching the touchpad; and

sending out a touch signal if the touching time reaches a second preset time, T_Touch,

wherein object number on the touchpad remains constant when calculating the touching time.

3. The multiple objects detection method of claim 2, further comprising calculating the locations of the at least two objects and sending out a location signal.

4. A multiple objects detection method for a capacitive touchpad, comprising:

verifying at least two objects touch the touchpad;

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when at least one value of the first and second peak value is smaller than a threshold value;

wherein if the first or second peak value remains less than the threshold value within a preset time, T_LiftDetect, and maintains a continuously decreasing trend during the preset time, T_LiftDetect, wherein such signifies that at least one object of the at least two objects has been removed from the touchpad.

5. The multiple objects detection method of claim 4 wherein steps of verifying the at least two objects touch the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are larger than a threshold value;

wherein if the sensed value remains greater than the threshold value within a second preset time, T_DownDetect, and maintains a continuously increasing trend during the second preset time, T_DownDetect, wherein such signifies that the at least two objects are touching the touchpad.

6. The multiple objects detection method of claim 4, further comprising:

calculating the leaving time of the at least one object leaving the touchpad;

sending out a leaving signal when the leaving time is greater than a second preset time, T_LiftGesture; and

calculating the object number on the touchpad;

wherein if the object number left on the touchpad is not zero, calculate the object location left on the touchpad, send out a location signal.

7. A multiple objects detection method for capacitive touchpad, comprising:

verifying at least two objects touching the touchpad;

calculating object number touching the touchpad;

calculating touching time of the at least two objects touching the touchpad;

if the touching time is smaller than a first preset time, T_TapDown, verify all objects have left the touchpad;

calculating the leaving time of all the objects leaving the touchpad; and

if the leaving time is greater than a second preset time, T_TapLift, send out a single click signal;

wherein, the object number on the touchpad remains constant when the touching time is calculated.

8. The multiple objects detection method of claim 7 wherein the steps of verifying at least two objects touching the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are larger than a threshold value;

wherein if the sensed value remains greater than the threshold value within a third preset time, T_DownDetect, and maintains a continuously increasing trend during the third preset time, T_DownDetect, wherein such signifies that the at least two objects are touching the touchpad.

9. The multiple objects detection method of claim 8, further comprising calculating the locations of the at least two objects and sending out a location signal.

10. The multiple objects detection method of claim 7 wherein the steps of verifying all objects leaving the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are smaller than a threshold value;

wherein if the sensed value remains less than the threshold value within a third preset time, T_LiftDetect, and maintains a continuously decreasing trend during the third preset time, T_LiftDetect, wherein such signifies that the at least two objects leave the touchpad.

11. A multiple objects detection method for capacitive touchpad, comprising:

verifying at least two objects touching the touchpad;

calculating object number touching the touchpad;

calculating a first touching time of the at least two objects touching the touchpad;

if the first touching time is smaller than a first preset time, T_TapDown, verify the at least two objects have left the touchpad;

calculating the leaving time of the at least two objects leaving the touchpad; and

if the leaving time is smaller than a second preset time T_TapLift, then verify at least two objects touch the touchpad;

calculating a second touching time of the at least two objects touching the touchpad;

if the second touching time is smaller than a third preset time T_DragDown, verify the at least two objects have left the touchpad; and

send out a double click signal;

wherein, the object number touching the touchpad remains constant when the first and second touching time are calculated.

12. The multiple objects detection method of claim 11 wherein the steps of verifying at least two objects touching the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are larger than a threshold value;

wherein if the sensed value remains greater than the threshold value within a fourth preset time, T_DownDetect, and maintains a continuously increasing trend during the fourth preset time, T_DownDetect, wherein such signifies that the at least two objects are touching the touchpad.

13. The multiple objects detection method of claim 11 wherein the steps of verifying at least two objects leaving the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are smaller than a threshold value;

wherein if the sensed value remains less than the threshold value within a fourth preset time, T_LiftDetect, and maintains a continuously decreasing trend during the fourth preset time, T_LiftDetect, wherein such signifies that the at least two objects leave the touchpad.

14. The multiple objects detection method of claim 11, further comprising calculating the locations of the at least two objects and sending out a location signal.

15. A multiple objects detection method for capacitive touchpad, comprising:

verifying at least two objects touching the touchpad;

calculating object number touching the touchpad;

calculating the touching time of the at least two objects touching the touchpad;

if the touching time is larger than a first preset time T_TapDown, verify at least one object of the at least two objects has left the touchpad;

calculating object number left on the touchpad; and

sending out a dragging signal;

wherein the object number left on the touchpad remains constant when the touching time is calculated, and after at least one object has been removed from the touchpad, the object number left on the touchpad must be greater than or equal to 1.

16. The multiple objects detection method of claim 15 wherein the steps of verifying at least two objects touching the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when both the values of the first and second peak are larger than a threshold value;

wherein if the sensed value remains greater than the threshold value within a second preset time, T_DownDetect, and maintains a continuously increasing trend during the second preset time, T_DownDetect, wherein such signifies that the at least two objects are touching the touchpad.

17. The multiple objects detection method of claim 15 wherein the steps of verifying at least one object of the at least two objects has been removed from the touchpad comprising:

detecting sensed value on the touchpad and getting at least a first peak value and a second peak value; and

calculating the change of the sensed value when at least one of the first and second peak value is smaller than a threshold value;

wherein if the first or second peak value remains less than the threshold value within a second preset time, T_LiftDetect, and maintains a continuously decreasing trend during the second preset time, T_LiftDetect, wherein such signifies that at least one object of the at least two objects has been removed from the touchpad.

18. The multiple objects detection method of claim 15, further comprising calculating the locations of all objects left on the touchpad and sending out a location signal.