Apparatus and method for reducing average scan rate to detect a conductive object on a sensing device

• US 8,144,125 B2
• Filed: 03/30/2006
• Issued: 03/27/2012
• Est. Priority Date: 03/30/2006
• Status: Expired due to Fees

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Peng, Tao, Qin, Zheng
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): SHARIFI-TAFRESHI, KOOSHA
• Application Number:
  US11/396,179
• Publication Number:
  US 20070229468A1
• Time in Patent Office: 2,189 Days
• Field of Search: 345/173, 345/174, 345/175, 345/178, 178 1801- 2004, 715/863, 715/864
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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 3/04847 Interaction techniques to control parameter settings, e.g. interaction with sliders or dials

Abstract

An apparatus and method to reduce an average scan rate to detect a conductive object on a sensing device. The method may include detecting a presence of a conductive object in a first area of a sensing device using a first scan of the sensing device, and detecting the presence of the conductive object to determine a position of the conductive object within the first area using a second scan of the first area of the sensing device. The apparatus may include a plurality of sensor elements coupled to a switch circuit. The switch circuit may include two settings for first and second scans.

Claims

1. A method, comprising:

detecting a presence of a conductive object in a first area of a sensing device using a first scan of the sensing device, wherein the first area is less than an entire area of the sensing device, wherein the sensing device comprises a plurality of first scan groups, wherein each of the plurality of first scan groups comprises two or more sensor elements coupled together during the first scan; and

detecting the presence of the conductive object to determine a position of the conductive object within the first area using a second scan of the first area of the sensing device, wherein detecting the presence of the conductive object within the first area using the second scan comprises;

selecting a second scan group that includes the first area in which the presence of the conductive object is detected during the first scan, wherein the second scan group includes two or more sensor elements that are not coupled together during the second scan; and

scanning the two or more sensor elements of the selected second scan group that includes the first area during the second scan, wherein each sensor element of the two or more sensor elements is separately scanned during the second scan.

2. The method of claim 1, further comprising determining the position of the conductive object within the first area using the second scan.

3. The method of claim 1, wherein detecting the presence of the conductive object in the first area using the first scan comprises:

scanning the plurality of first scan groups of sensor elements during the first scan, wherein each first scan group of sensor elements is separately scanned during the first scan; and

determining the first area in which the presence of the conductive object is detected based on the first scan.

4. The method of claim 3, wherein detecting the presence of the conductive object within the first area using the second scan further comprises

selecting a sensor element of the two or more sensor elements of the selected second scan group that includes the detected presence of the conductive object based on the second scan.

5. The method of claim 4, wherein scanning the plurality of first scan groups of sensor elements during the first scan comprises:

coupling one or more capacitance sensors to the plurality of first scan groups, wherein each sensor element of each first scan group is coupled to a same capacitance sensor of the one or more capacitance sensors;

scanning the plurality of first scan groups during the first scan using the one or more capacitance sensors coupled to the plurality of first scan groups;

detecting the presence of the conductive object in the first area using the one or more capacitance sensors; and

selecting a first scan group of the plurality of first scan groups that includes the first area in which the presence of the conductive object is detected using the first scan.

6. The method of claim 5, wherein scanning two or more sensor elements of the selected first scan group during the second scan comprises:

coupling the one or more capacitance sensors to two or more sensor elements of the second scan group;

scanning the two or more sensor elements during the second scan using the one or more capacitance sensors coupled to each sensor element of the second scan group;

detecting the presence of the conductive object using the one or more capacitance sensors; and

selecting a sensor element of the two or more sensor elements of the second scan group on which the presence of the conductive object is detected using the second scan.

7. The method of claim 6, wherein each of the plurality of first scan group comprises a number of sensor elements that is equal to √

{square root over (N)} rounded down to the nearest natural number, wherein N is a total number of sensor elements of the sensing device.

8. The method of claim 7, wherein an average first scan rate to detect the presence of the conductive object in the first area using the first scan is approximately (√

{square root over (N)}+1)/2 cycles per scan.

9. The method of claim 8, wherein an average scan rate of the second scan to detect the presence within the first area using the second scan is approximately (√

{square root over (N)}+1)/2 cycles per scan.

10. The method of claim 9, wherein an average scan rate to determine the position of the conductive object on the sensing device is approximately (2√

{square root over (N)}+1)/2 cycles per scan.

11. The method of claim 1, wherein detecting the presence of the conductive object in the first area using the first scan comprises:

grouping a plurality of sensor elements of the sensing device into the plurality of first scan groups;

scanning the first scan groups during the first scan using one or more capacitance sensors coupled to the plurality of first scan groups; and

detecting the presence of the conductive object on one of the first scan groups using the first scan, and wherein detecting the presence of the conductive object to determine the position of the conductive object within the first area comprises;

grouping two or more sensor elements of the sensing device into a second scan group, wherein the second scan group comprises the two or more sensor elements of the one first scan group that detected the presence of the conductive object;

scanning the second scan group during the second scan using the one or more capacitance sensors coupled to the second scan group; and

detecting the presence of the conductive object on one sensor element of the two or more sensor elements of the second scan group using the second scan.

12. The method of claim 1, wherein detecting the presence of the conductive object in the first area using the first scan comprises:

grouping a plurality of sensor elements of the sensing device into the plurality of first scan groups;

scanning the first scan groups during the first scan using one or more capacitance sensors coupled to the plurality of first scan groups; and

detecting the presence of the conductive object on two of the plurality of first scan groups using the first scan, and wherein detecting the presence of the conductive object to determine the position of the conductive object within the first area comprises;

grouping two or more sensor elements of the sensing device into a second scan group, wherein the second scan group includes sensor elements from the two first scan groups that detected the presence of the conductive object;

scanning the second scan group during the second scan using the one or more capacitance sensors coupled to the second scan group; and

detecting the presence of the conductive object on one sensor element of the two or more sensor elements of the second scan group using the second scan.

13. An apparatus, comprising:

a plurality of sensor elements to detect a presence of a conductive object on the sensing device;

a switch circuit coupled to the plurality of sensor elements, wherein the switch circuit is configured to group the plurality of sensor elements into multiple first scan groups and a second scan group, wherein each of the first scan groups comprises two or more of the plurality of sensor elements coupled together during the first scan, and wherein the second scan group includes two or more of the plurality of sensor elements that are not coupled together during the second scan.

14. The apparatus of claim 13, further comprising a processing device coupled to the switch circuit, wherein the processing device comprises the one or more capacitance sensors coupled to the switch circuit.

15. The apparatus of claim 13, wherein each first scan group comprises a number of sensor elements that is equal to √

{square root over (N)} rounded down to the nearest natural number, wherein N is a total number of the plurality of sensor elements of the sensing device.

16. The apparatus of claim 15, wherein the processing device is configured to detect the average scan rate to detect the position is approximately (2√

{square root over (N)}+1)/2 cycles per scan.

17. The apparatus of claim 13, further comprising one or more capacitance sensors coupled to the switch circuit, wherein the one or more capacitance sensors are configured to measure capacitance on the plurality of sensor elements, and wherein the switch circuit comprises first and second settings, wherein the first setting is configured to couple the one or more capacitance sensors to the two or more sensor elements that are coupled together for each of the multiple first scan groups, and wherein the second setting is configured to couple the one or more capacitance sensors, during the second scan, to the two or more sensor elements of the first scan group in which the presence of the conductive object is detected during the first scan.

18. An apparatus, comprising:

a plurality of sensor elements of a sensing device;

means for coupling the plurality of sensor elements into first and second scan groups, wherein the first scan group comprises two or more of the plurality of sensor elements coupled together during the first scan, and wherein the second scan group includes two or more of the plurality of sensor elements that are not coupled together during the second scan; and

means for determining a position of a presence of a conductive object on the sensing device using the first and second scan groups.

19. The apparatus of claim 18, further comprising means for reducing an average scan rate to detect the position of the conductive object on the sensing device.

20. The apparatus of claim 19, wherein the average scan rate to detect the position is approximately (2√

{square root over (N)}+1)/2 cycles per scan, wherein N is a total number of the plurality of sensor elements of the sensing device.