METHOD FOR IMPROVING SCAN TIME AND SENSITIVITY IN TOUCH SENSITIVE USER INTERFACE DEVICE

• US 20090009195A1
• Filed: 07/03/2008
• Published: 01/08/2009
• Est. Priority Date: 07/03/2007
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Seguine, Ryan D.
• Granted Patent: US 8,508,244 B2
• Time in Patent Office: Days
• US Class Current: 324/690
• CPC Class Codes: G01D 5/24 by varying capacitance

Abstract

System and method for optimizing the consumption of power while maintaining performance in capacitive sensor arrays. A limited sensing area is used to improve the update rate and sensitivity of a row/column array of capacitive sensors. According to one embodiment, a method is provided for scanning a plurality of capacitive sensors by: detecting a stimulus in the field of capacitive sensors, scanning the field of capacitive sensors to determine the position of the stimulus. Once the position of the stimulus is determined, a subsection of the field comprising window corresponding to the position of the stimulus remains activated while the remaining sensors in the field are deactivated.

Claims

1. A method for scanning a plurality of capacitive sensors, the method comprising:

detecting a stimulus in a field of capacitive sensors comprising said plurality of capacitive sensors;

scanning said field of capacitive sensors to determine a first position of said stimulus in said field of capacitive sensors; and

scanning a subsection of said plurality of capacitive sensors within said field of capacitive sensors at a first sensitivity level,

wherein said subsection comprises capacitive sensors proximate to said first position of said stimulus.

2. The method of claim 1, wherein said subsection comprises:

a capacitive sensor activated by a proximity to said stimulus; and

a capacitive sensor corresponding to a subsequent displacement of said stimulus.

3. The method of claim 2, wherein said capacitive sensor corresponding to a subsequent displacement of said stimulus comprises a capacitive sensor proximate to said capacitive sensor activated by said proximity to said stimulus.

4. The method of claim 1, wherein said detecting a stimulus in said field of capacitive sensors comprises scanning all capacitive sensors in said field at a second sensitivity level, wherein said second sensitivity level is lower than said first sensitivity level.

5. The method of claim 1, wherein scanning said field of capacitive sensors to determine a first position of said stimulus further comprises:

determining said first position of said stimulus according to a centroid positioning algorithm of activated sensors.

6. The method of claim 1, wherein said scanning of said subsection is performed while said stimulus is detected in said first position.

7. The method of claim 1 further comprising:

updating said position of said stimulus according to a motion of said stimulus; and

adjusting said scanning of said subsection according to said motion of said stimulus.

8. The method of claim 7, wherein said motion of said stimulus comprises a displacement of said stimulus from said first position to a second position in said subsection of capacitive sensors.

9. The method of claim 7, wherein said adjusting said scanning of said subsection comprises scanning a non-scanned capacitive sensor corresponding to said second position of said stimulus in said subsection.

10. The method of claim 7, wherein adjusting said scanning of said subsection comprises terminating said scanning of a capacitive sensor which does not correspond to said second position of said stimulus.

11. The method of claim 1, wherein said scanning of said subsection consumes power at a lower rate than said scanning of said field of capacitive sensors.

12. A method for scanning a capacitive sensor array, the method comprising:

detecting a presence of a finger in said capacitive sensor array using a first scan rate;

determining a location of said finger in said capacitive sensor array during a first mode;

determining a halo of capacitive sensors corresponding to said location of said finger in said capacitive sensor array;

scanning said halo of capacitive sensors during a second mode at a second scan rate; and

modifying said halo of capacitive sensors according to a displacement of said finger during said second mode.

13. The method of claim 12, wherein determining a location of said finger in said capacitive sensor array during said first mode comprises:

scanning all of said capacitive sensor array at a second scan rate to determine said location of said finger.

14. The method of claim 12, wherein said determining said halo of capacitive sensors comprises:

scanning a plurality of capacitive sensors that are activated and correspond to said location of said finger in said array; and

scanning a plurality of other capacitive sensors comprising a perimeter along said plurality of capacitive sensors corresponding to said location.

15. The method of claim 12, wherein said first scan rate consumes power at a lower rate than said second scan rate.

16. A system for scanning for a position of a stimulus in a field of sensors, the system comprising:

a controller; and

an array of sensors, said sensors comprising;

a conductive pad;

surrounding ground; and

a connection coupling said sensors to said controller,

wherein, said sensors comprising said array are scanned at a high rate to determine a position of said stimulus during a first state, and a subsection of sensors comprising said position of said stimulus along with a plurality of sensors corresponding to a subsequent displacement of said stimulus is scanned during a second state.

17. The system of claim 16, wherein a plurality of sensors corresponding to a subsequent displacement comprises a halo of sensors forming a perimeter along said capacitive sensors corresponding to said location.

18. The system of claim 17, wherein said perimeter is modified according to a displacement of said stimulus in said field of sensors.

19. The system of claim 16, wherein said second state consumes power at a reduced rate relative to said first state.

20. The system of claim 16, wherein said sensors are capacitive sensors.