Method for object detection on a capacitive touchpad

• US 20060279551A1
• Filed: 12/28/2005
• Published: 12/14/2006
• Est. Priority Date: 06/08/2005
• Status: Active Grant

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: Tang, Kuan-Chun, Lii, Jia-Yih
• Granted Patent: US 8,102,376 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

In an object detection method for a capacitive touchpad, at least one reference time interval is used to distinguish whether a variation of the sensed value on the touchpad is resulted from an operation of an object on the touchpad, actions such as an object touch down to the touchpad, an object lift from the touchpad and an object movement on the touchpad are then determined, and operations corresponding to various gestures are correctly detected.

Claims

1. An object detection method for a capacitive touchpad, comprising the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is greater than a threshold; and

determining that an object touches down to the touchpad if the sensed value maintains greater than the threshold in an increasing trend within a reference time interval.

2. The method of claim 1, further comprising the steps of:

counting a time duration that the object lasts on the touchpad if the object is determined to touch down to the touchpad; and

producing a touch signal if the time duration reaches a second reference time interval.

3. The method of claim 2, further comprising the step of calculating a position information of the object if the time duration reaches the second reference time interval.

4. An object detection method for a capacitive touchpad, comprising the steps of:

monitoring a sensed value on the touchpad when an object touches on the touchpad;

monitoring a variation of the sensed value when the sensed value is less than a threshold; and

determining that the object leaves from the touchpad if the sensed value maintains less than the threshold in a decreasing trend within a reference time interval.

5. The method of claim 4, further comprising the step of verifying that the object touches on the touchpad before the step of monitoring a sensed value on the touchpad.

6. The method of claim 4, further comprising the steps of:

counting a time duration after the object is determined to leave from the touchpad; and

producing a lift signal if the time duration reaches a second reference time interval.

7. An object detection method for a capacitive touchpad, comprising the steps of:

monitoring a sensed value on the touchpad when an object touches on the touchpad;

monitoring a variation of the sensed value; and

determining that the object moves in a first direction if, within a reference time interval, the sensed value maintains an increasing trend in the first direction and a decreasing trend in a second direction opposite to the first direction.

8. The method of claim 7, further comprising the step of verifying that the object touches on the touchpad before the step of monitoring a sensed value on the touchpad.

9. An object detection method for a capacitive touchpad, comprising the steps of:

verifying that an object moves on the touchpad;

calculating a position information of the object and sending out the position information; and

repeating the previous step if the object is detected to move on the touchpad again before a time duration after the previous time the object is detected to move on the touchpad reaches a reference time interval.

10. The method of claim 9, wherein the step of verifying that an object moves on the touchpad comprises the steps of:

monitoring a sensed value on the touchpad when the object touches on the touchpad;

monitoring a variation of the sensed value; and

determining that the object moves in a first direction if, within a second reference time interval, the sensed value maintains an increasing trend in the first direction and a decreasing trend in a second direction opposite to the first direction.

11. The method of claim 10, further comprising the step of verifying that the object touches on the touchpad before the step of monitoring a sensed value on the touchpad.

12. An object detection method for a capacitive touchpad, comprising the steps of:

verifying that an object touches down to the touchpad;

counting a first time duration that the object lasts on the touchpad;

verifying that the object leaves from the touchpad if the object is detected to leave the touchpad before the first time duration reaches a first reference time interval;

counting a second time duration after the object leaves the touchpad; and

producing a tap signal if the second time duration reaches a second reference time interval.

13. The method of claim 12, wherein the step of verifying that an object touches down to the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is greater than a threshold; and

determining that the object touches down to the touchpad if the sensed value maintains greater than the threshold in an increasing trend within a third reference time interval.

14. The method of claim 12, wherein the step of verifying that the object leaves from the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is less than a threshold; and

determining that the object leaves from the touchpad if the sensed value maintains less than the threshold in a decreasing trend within a third reference time interval.

15. The method of claim 12, further comprising the step of calculating a position information of the object and sending out the position information if the tap signal is produced.

16. An object detection method for a capacitive touchpad, comprising the steps of:

verifying that an object touches down to the touchpad;

counting a first time duration that the object lasts on the touchpad;

verifying that the object leaves from the touchpad if the object is detected to leave the touchpad before the first time duration reaches a first reference time interval;

counting a second time duration after the object leaves the touchpad;

verifying that the object touches down to the touchpad again if the touchpad is detected to be touched again before the second time duration reaches a second reference time interval;

counting a third time duration that the object lasts on the touchpad in the second touch; and

producing a drag signal if the third time duration reaches a third reference time interval.

17. The method of claim 16, wherein the step of verifying that the object touches down to the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is greater than a threshold; and

determining that the object touches down to the touchpad if the sensed value maintains greater than the threshold in an increasing trend within a fourth reference time interval.

18. The method of claim 16, wherein the step of verifying that the object leaves from the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is less than a threshold; and

determining that the object leaves from the touchpad if the sensed value maintains less than the threshold in a decreasing trend within a fourth reference time interval.

19. The method of claim 16, further comprising the step of calculating a position information of the object and sending out the position information if the drag signal is produced.

20. An object detection method for a capacitive touchpad, comprising the step of:

verifying that an object touches down to the touchpad;

counting a first time duration that the object lasts on the touchpad;

verifying that the object leaves from the touchpad if the object is detected to leave the touchpad before the first time duration reaches a first reference time interval;

counting a second time duration after the object leaves the touchpad;

verifying that the object touches down to the touchpad again if the touchpad is detected to be touched again before the second time duration reaches a second reference time interval;

counting a third time duration that the object lasts on the touchpad in the second touch;

verifying that the object leaves from the touchpad if the object is detected to leave the touchpad again before the third time duration reaches a third reference time interval; and

producing a double tap signal if the object is verified to leave from the touchpad in the previous step.

21. The method of claim 20, wherein the step of verifying that the object touches down to the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is greater than a threshold; and

determining that the object touches down to the touchpad if the sensed value maintains greater than the threshold in an increasing trend within a fourth reference time interval.

22. The method of claim 20, wherein the step of verifying that the object leaves from the touchpad comprises the steps of:

monitoring a sensed value on the touchpad;

monitoring a variation of the sensed value when the sensed value is less than a threshold; and

determining that the object leaves from the touchpad if the sensed value maintains less than the threshold in a decreasing trend within a fourth reference time interval.

23. The method of claim 20, further comprising the step of calculating a position information of the object and sending out the position information if the double tap signal is produced.