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

• US 8,493,351 B2
• Filed: 03/14/2011
• Issued: 07/23/2013
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Peng, Tao, Qin, Zheng
• Primary Examiner(s): Sharifi-Tafreshi, Koosha
• Application Number:
  US13/047,035
• Publication Number:
  US 20120044194A1
• Time in Patent Office: 862 Days
• Field of Search: 345173-178, 178 1801- 1811
• 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

A switch circuit and method is described. In one embodiment, the switch circuit is configured to couple each of a plurality of plurality of capacitive sense elements and a plurality of capacitance sensors in different modes. In a first mode, the switch circuit is configured to couple each of the plurality of capacitance sensors to a group of two or more of the plurality of capacitive sense elements. In a second mode, the switch circuit is configured to couple the plurality of capacitance sensors to individual ones of the two or more of the plurality of capacitive sense elements in one of the groups.

Claims

1. An apparatus, comprising:

a plurality of capacitive sense elements;

a first capacitance sensor and a second capacitance sensor; and

a switch circuit configured to couple the plurality of capacitive sense elements to the first and second capacitance sensors in different modes,

wherein the switch circuit is configured to couple the first capacitance sensor to a first group of two or more of the plurality of capacitive sense elements in a first mode,

wherein the switch circuit is configured to couple the second capacitance sensor to a second group of two or more of the plurality of capacitive sense elements, and

wherein the switch circuit is configured to couple at least one of the first or second capacitance sensors to individual ones of the two or more of the plurality of capacitive sense elements in one of the first or second groups in a second mode.

2. The apparatus of claim 1, wherein the switch circuit is configured to switch between the first mode and the second mode when a presence of a conductive object is detected in an area corresponding to one of the first or second groups in the first mode.

3. The apparatus of claim 1, further comprising a processing device comprising the switch circuit and the first and second capacitance sensors, wherein the processing device is configured to control the switch circuit to couple the first and second capacitance sensors to the plurality of capacitive sense elements in the first and second modes.

4. The apparatus of claim 3, wherein:

the processing device is configured to perform a first scan to detect a presence of a conductive object while the switch circuit is in the first mode;

the processing device is configured to perform a second scan when the presence of the conductive object is detected in the first scan; and

the processing device is configured to not perform the second scan when the presence of the conductive object is not detected in the first scan.

5. The apparatus of claim 4, wherein:

in the first scan, the processing device measures, using the first capacitance sensor, a first capacitance on the first group of the two or more capacitive sense elements coupled together;

in the first scan, the processing device measure, using the second capacitance sensor, a second capacitance on the second group of the two or more capacitive sense elements coupled together; and

in the second scan, the processing device measures, using at least one of the first capacitance sensor or the second capacitance sensor, a third capacitance on each individual one of the two or more capacitive sense elements of one of the first or second groups,

wherein the one group corresponds to a first area in which the presence of the conductive object is detected during the first scan, and

wherein the two or more of the plurality of capacitive sense elements in the one group are not coupled together in the second mode.

6. An apparatus, comprising:

a two-dimensional capacitive sense array comprising a plurality of rows of capacitive sense elements and a plurality of columns of capacitive sense elements;

a first capacitance sensor;

a second capacitance sensor; and

a switch circuit configured to couple the first and second capacitance sensors to the two-dimensional capacitive sense array in different modes, wherein;

in a first mode, the switch circuit is configured to couple the first capacitance sensor to a first group of two or more of the plurality of rows, and to couple the second capacitance sensor to a second group of two or more of the plurality of rows;

in a second mode, the switch circuit is configured to couple the second capacitance sensor to a third group of two or more of the plurality of columns, and to couple the second capacitance sensor to a fourth group of two or more of the plurality of columns;

in a third mode, the switch circuit is configured to couple at least one of the first capacitance sensor or the second capacitance sensor to individual ones of the two or more of the plurality of rows in one of the first or second groups of rows; and

in a fourth mode, the switch circuit is configured to couple at least one of the first capacitance sensor or the second capacitance sensor to individual ones of the two or more of the plurality of columns in one of the third or fourth groups of columns.

7. The apparatus of claim 6, wherein:

the switch circuit is configured to switch between the first mode and the third mode when a presence of a conductive object is detected in an area corresponding to the one group of rows in the first mode, and

the switch circuit is configured to switch between the second mode and the fourth mode when the presence of the conductive object is detected in the area corresponding to the one group of columns in the second mode.

8. The apparatus of claim 6, further comprising a processing device comprising the switch circuit and the first and second capacitance sensors, wherein the processing device is configured to control the switch circuit to couple the first and second capacitance sensors to the plurality of rows and plurality of columns in the first, second, third, and fourth modes.

9. The apparatus of claim 6, wherein:

the processing device is configured to perform a first scan of the first and second groups of rows to detect a presence of a conductive object while the switch circuit is in the first mode;

the processing device is configured to perform a second scan of the third and fourth groups of columns to detect a presence of the conductive object while the switch circuit is in the second mode;

the processing device is configured to perform a third scan when the presence of the conductive object is detected in the first scan;

the processing device is configured to perform a fourth scan when the presence of the conductive object is detected in the second scan; and

the processing device is configured to not perform the third and fourth scan when the presence of the conductive object is not detected in the first and second scans.

10. The apparatus of claim 9, wherein:

in the first scan, the processing device measures, using the first capacitance sensor, a first capacitance on the first group of rows having the two or more rows coupled together;

in the first scan, the processing device measures, using the second capacitance sensor, a second capacitance on the second group of rows having the two or more rows coupled together;

in the second scan, the processing device measures, using the first capacitance sensor, a third capacitance on the third group of columns having the two or more columns coupled together;

in the second scan, the processing device measures, using the second capacitance sensor, a fourth capacitance on the fourth group of columns having the two or more columns coupled together;

in the third scan, the processing device measures, using the first and second capacitance sensors, capacitances on each individual one of the two or more rows of the one group of rows,

wherein the one group of rows corresponds to a first area in which the presence of the conductive object is detected during the first scan, and

wherein the two or more of the plurality of rows in the one group of rows are not coupled together in the third scan; and

in the fourth scan, the processing device measures, using the first and second capacitance sensors, capacitances on each individual one of the two or more columns of the one group of columns,

wherein the one group of columns corresponds to the first area in which the presence of the conductive object is detected during the second scan, and

wherein the two or more of the plurality of columns in the one group of columns are not coupled together in the fourth scan.

11. The apparatus of claim 10, wherein the processing device is configured to perform the first, second, third, and fourth scans in the following order:

the first scan, the second scan, the third scan, and the fourth scan.

12. The apparatus of claim 11, wherein the processing device is configured to perform the first, second, third, and fourth scans in the following order:

the first scan, the third scan, the second scan, and the fourth scan.

13. A method, comprising

coupling a plurality of capacitance capacitive sense elements to a first capacitance sensor and a second capacitance sensor in different modes, wherein said coupling comprises:

coupling, using a switch circuit, the first capacitance sensor to a first group of two or more of the plurality of capacitive sense elements in a first mode;

coupling, using the switch circuit, the second capacitance sensor to a second group of two or more of the plurality of capacitive sense elements in the first mode; and

coupling, using the switch circuit, at least one of the first capacitance sensor or the second capacitance sensor to individual ones of the two or more of the plurality of capacitive sense elements in one of the first group or second group in a second mode.

14. The method of claim 13, further comprising switching between the first mode and the second mode when a presence of a conductive object is detected in an area corresponding to the one group in the first mode.

15. The method of claim 13, further comprising:

performing a first scan to detect a presence of a conductive object while the switch circuit is in the first mode; and

performing a second scan when the presence of the conductive object is detected in the first scan,

wherein the second scan is not performed when the presence of the conductive object is not detected in the first scan.

16. The method of claim 15, further comprising:

in the first scan, measuring a first capacitance on each of the first and second groups, each of the groups having the two or more capacitive sense elements coupled together; and

in the second scan, measuring a second capacitance on each individual one of the two or more capacitive sense elements of one of the groups,

wherein the one group corresponds to a first area in which the presence of the conductive object is detected during the first scan, and

wherein the two or more of the plurality of capacitive sense elements in the one group are not coupled together in the second mode.

17. The method of claim 13, wherein the plurality of capacitive sense elements are arranged as a plurality of rows and a plurality of columns of a two-dimensional capacitive sense array, and wherein the method further comprises:

in the first mode,

coupling the first capacitance sensor to a first group of two or more of the plurality of rows,

coupling the second capacitance sensor to a second group of two or more of the plurality of rows;

coupling the first capacitance sensor to a third group of two or more of the plurality of columns;

coupling the second capacitance sensor to a fourth group of two or more of the plurality of columns; and

in the second mode,

coupling at least one of the first capacitance sensor or second capacitance sensor to individual ones of the two or more of the plurality of rows in one of the first and second groups of rows, and

coupling at least one of the first capacitance sensor or second capacitance sensor to individual ones of the two or more of the plurality of columns in one of the third and fourth groups of columns.

18. The method of claim 17, further comprising:

performing a first scan of the first and second groups of rows to detect a presence of a conductive object while the switch circuit is in the first mode;

performing a second scan of the third and fourth groups of columns to detect a presence of the conductive object while the switch circuit is in the first mode;

performing a third scan when the presence of the conductive object is detected in the first scan; and

performing a fourth scan when the presence of the conductive object is detected in the second scan.

19. The method of claim 18, further comprising:

in the first scan, measuring a first capacitance on each of the first and second groups of rows, each of the groups of rows having the two or more rows coupled together;

in the second scan, measuring a second capacitance on each of the third and fourth groups of columns, each of the groups of columns having the two or more columns coupled together; and

in the third scan, measuring a third capacitance on each individual one of the two or more rows of the one group of rows,

wherein the one group of rows corresponds to a first area in which the presence of the conductive object is detected during the first scan, and

wherein the two or more of the plurality of rows in the one group of rows are not coupled together in the third scan; and

in the fourth scan, measuring a fourth capacitance on each individual one of the two or more columns of the one group of columns,

wherein the one group of columns corresponds to the first area in which the presence of the conductive object is detected during the second scan, and

wherein the two or more of the plurality of columns in the one group of columns are not coupled together in the fourth scan.

20. The method of claim 18, wherein said performing the third scan is performed before said performing the second scan.