SYSTEM AND METHOD OF SCANNING AN ARRAY OF SENSORS

• US 20090185062A1
• Filed: 12/19/2008
• Published: 07/23/2009
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Goh, Eng-Siong, Ng, Chee Yu, Noviello, Giuseppe
• Granted Patent: US 8,284,080 B2
• Time in Patent Office: Days
• US Class Current: 348/302
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

Aspects of the invention relate to a method and apparatus for scanning an array of sensors. More particularly, the invention is directed towards scanning an array of sensors to accurately determine actuated sensors on a contact-sensitive surface. In one embodiment, three sets of sensing lines can be incorporated into the sensing area for ghost-free detection of up to two keys. Further in other embodiments, n sets of sensing lines can be incorporated into the sensing area for ghost free detection of up to n−1 keys.

Claims

1. A method of scanning an array of sensors, comprising the steps of:

scanning a first set of sensing lines, wherein a sensing line of the first set is coupled with a plurality of sensors in an x-axis direction of the array;

scanning a second set of sensing lines, wherein a sensing line of the second set is coupled with a plurality of sensors in a y-axis direction of the array;

scanning a third set of sensing lines, wherein a sensing line of the third set is coupled with a plurality of sensors in a third direction of the array different from the x-axis and y-axis direction; and

determining a location of the sensor that has been actuated.

2. The method of claim 1, wherein the sensing line of the third set comprises sensors of the array which do not share sensing lines of the first and the second set.

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

scanning a fourth set of sensing line, wherein a sensing line of the fourth set of sensing lines is coupled with a plurality of sensors of the array along another direction of the array.

4. The method of claim 3, wherein the sensing line of the fourth set comprises keys of the array which do not share sensing lines of the first to third set.

5. The method of claim 1, wherein the sensors comprise capacitive sensors.

6. The method of claim 1, wherein the sensors comprise mechanical switch type keys.

7. An array of sensors, comprising:

a first set of sensing lines, wherein a sensing line of the first set comprises a plurality of sensors of the array along a first direction of the array;

a second set of sensing lines, wherein a sensing line of the second set comprises a plurality of sensors of the array along a second direction of the array; and

a third set of sensing lines, wherein a sensing line of the third set comprises a plurality of the sensors of the array along a third direction of the array.

8. The array of claim 7, wherein the sensing line of the third set comprises sensors of the array which do not share sensing lines of the first and the second set.

9. The array of claim 7, further comprising:

a sensor circuit coupled to the first, second and third set of sensing lines configured to determine accurately whether a sensor has been detected.

10. The array of claim 9, wherein the sensor circuit comprises:

a plurality of controller pins coupled to the first, second and third set of sensing lines;

a line decoder unit coupled to the plurality of controller pins, wherein the line decoder is configured to determine actuated sensors of at least one sensor in the array of sensors;

a candidate generator unit coupled to the line decoder configured to generate a list of possible candidates of actuated sensors, wherein the list of possible candidates of actuated sensors includes the actuated sensors and ghost sensors; and

a validity checker unit coupled to the candidate generator unit configured to validate the list of possible candidates by removing ghost sensors, wherein the validity checker unit is capable of outputting an output signal including the actuated sensors.

11. The array of claim 7, wherein the sensors comprise capacitive sensors.

12. The array of claim 7, wherein the sensors comprise mechanical switch type keys.

13. An apparatus to reduce inaccuracy in detecting actuated sensors on a contact-sensitive surface, comprising:

a plurality of sensor lines, wherein each of the plurality of sensor lines comprise a plurality of sensors;

a plurality of controller pins coupled to the plurality of the sensor lines;

a line decoder unit coupled to the plurality of controller pins, wherein the line decoder is configured to determine the actuated sensors of at least one sensor in the array of sensors;

a candidate generate unit coupled to the line decoder configured to generate a list of possible candidates of the actuated sensors, wherein the list of possible candidates of the actuated sensors includes the actuated sensors and ghost sensors; and

a validity checker unit coupled to the candidate generator configured to validate the list of possible candidates by removing ghost sensors, wherein the validity checker unit is capable of outputting an output signal including the actuated sensors.

14. The apparatus of claim 13, wherein a number of the plurality of controller pins equals (X+Y)+Max(X,Y), wherein X is the number of sensors in an x-axis direction of the plurality of sensors, wherein Y is the number of sensors in a y-axis direction, wherein Max(X,Y) is a greater of X or Y.

15. The apparatus of claim 13, wherein the sensors comprise capacitive sensors.

16. The apparatus of claim 13, wherein the sensors comprise mechanical switch type keys.

17. The apparatus of claim 13, wherein a number of the plurality of controller pins equals (X+Y)+N*Max(X,Y), wherein X is the number of sensors in an x-axis direction of the plurality of sensors, wherein Y is the number of sensors in a y-axis direction, wherein Max(X,Y) is a greater of X or Y, wherein N is a number of additional sensing lines not including the sensors in the x-axis or y-axis direction.

18. The apparatus of claim 13, wherein the contact sensitive surface is a liquid crystal display.

19. The apparatus of claim 13, wherein the contact sensitive surface is a plasma display.

20. The apparatus of claim 13, wherein the line decoder unit is implemented as at least one hardware module.