Two element slider with guard sensor

• US 20090184920A1
• Filed: 01/18/2008
• Published: 07/23/2009
• Est. Priority Date: 07/10/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Francis, Mark
• Granted Patent: US 8,581,853 B2
• Time in Patent Office: Days
• US Class Current: 345/156
• CPC Class Codes: G06F 2203/0339 Touch strips, e.g. orthogonal touch strips to control cursor movement or scrolling; single touch strip to adjust parameter or to implement a row of soft keys
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

A method for using a slider-based capacitive sensor to implement a user interface having discrete buttons. Button locations are designated on a slider-based capacitive sensor having at least two conductive traces such that a user input at any button location results in a capacitance change in the conductive traces. Locations of inputs are distinguishable by ratios between the capacitance changes of the conductive traces, which can be correlated to a particular button location. Ratio ranges corresponding to areas covered by each button are used to identify which button has received an input.

Claims

1. A method comprising:

measuring a capacitance value associated with each of a plurality of conductive traces, each of the plurality of conductive traces having a first end and a second end, wherein at least one of the plurality of conductive traces has a greater surface area near the first end than near the second end;

determining whether a ratio from the measured capacitance values is within one of a plurality of ratio ranges; and

identifying a user input location on the plurality of conductive traces, wherein the user input location is associated with the ratio range of the plurality of ratio ranges that the ratio from the measured capacitance values is determined to be within.

2. The method according to claim 1, further comprising measuring a capacitance value associated with a guard sensor trace, wherein at least a portion of the guard sensor trace is positioned alongside at least one conductive trace of the plurality of conductive traces.

3. The method according to claim 2, further comprising detecting a presence of a user input based on a comparison between a measured capacitance value associated with the guard sensor trace and at least one capacitance value associated with at least one of the plurality of conductive traces.

4. The method according to claim 1, further comprising:

determining a first count value from a capacitance associated with a first tapered conductive trace of the plurality of conductive traces;

determining a second count value from a capacitance associated with a second tapered conductive trace of the plurality of conductive traces;

determining a guard count value from a capacitance associated with the guard sensor trace;

determining a presence of a user input if the guard count value is not greater than half of the first count value and the guard count value is not greater than half of the second count value;

identifying a first button position as a location of the user input if the user input is determined to be present and the first count value is greater than two times the second count value;

identifying a second button position as the location of the user input if the user input is determined to be present, the first count value is greater than the second count value, and the first count value is not greater than two times the second count value;

identifying a third button position as the location of the user input if the user input is determined to be present, the first count value is not less than two-thirds of the second count value, and the first count value is less than the second count value;

identifying a fourth button position as the location of the user input if the user input is determined to be present, the first count value is not less than one-third of the second count value, and the first count value is less than two-thirds of the second count value; and

identifying a fifth button position as the location of the user input if the user input is determined to be present and the first count value is less than one-third of the second count value.

5. The method according to claim 1, wherein at least one ratio range from the plurality of ratio ranges includes only one of an upper limit or a lower limit.

6. The method according to claim 1, wherein the plurality of conductive traces includes a first conductive trace and a second conductive trace including two subtraces, wherein the first conductive trace is interleaved between the two subtraces of the second conductive trace and the first end of the first conductive trace is adjacent to the second end of the second conductive trace.

7. The method according to claim 1, wherein the plurality of conductive traces includes a first conductive trace and a second conductive trace, wherein the first conductive trace is positioned alongside the second conductive trace such that the first end of the first conductive trace is adjacent to the second end of the second conductive trace.

8. The method according to claim 7, wherein at least one of the plurality of conductive traces is curved along a circumference of a circle.

9. The method according to claim 1, wherein at least one of the plurality of conductive traces is made from a conductive polymer film.

10. An apparatus, comprising:

a processor configured to receive capacitance values measured from each of a plurality of conductive traces, each of the plurality of conductive traces having a first end and a second end, wherein at least one of the plurality of conductive traces has a greater surface area near the first end than near the second end, wherein the processor is further configured to determine whether a ratio from the received capacitance values is within one of a plurality of ratio ranges, the processor further configured to identify a user input location on the plurality of conductive traces, wherein the user input location is associated with the ratio range of the plurality of ratio ranges that the ratio from the received capacitance values is determined to be within.

11. The apparatus according to claim 10, wherein said processor is further configured to receive a capacitance value associated with a guard sensor trace, wherein the guard sensor trace is positioned alongside at least one conductive trace of the plurality of conductive traces.

12. The apparatus according to claim 11, wherein said processor is further configured to detect a presence of a user input based on a comparison between the capacitance value associated with the guard sensor trace and at least one capacitance value associated with at least one of the plurality of conductive traces.

13. The apparatus according to claim 10, wherein said processor is further configured to receive a capacitance value associated with a guard sensor trace, wherein the guard sensor trace at least partially surrounds at least one conductive trace of the plurality of conductive traces.

14. The apparatus according to claim 13, wherein said processor is further configured to

determine a first count value from a capacitance associated with a first tapered conductive trace of the plurality of conductive traces, determine a second count value from a capacitance associated with a second tapered conductive trace of the plurality of conductive traces, and determine a guard count value from a capacitance associated with the guard sensor trace,

the processor further configured to determine a presence of a user input if the guard count value is not greater than half of the first count value and the guard count value is not greater than half of the second count value,

the processor further configured to identify a first button position as a location of the user input if the user input is determined to be present and the first count value is greater than two times the second count value,

the processor further configured to identify a second button position as the location of the user input if the user input is determined to be present, the first count value is greater than the second count value, and the first count value is not greater than two times the second count value,

the processor further configured to identify a third button position as the location of the user input if the user input is determined to be present, the first count value is not less than two-thirds of the second count value, and the first count value is less than the second count value,

the processor further configured to identify a fourth button position as the location of the user input if the user input is determined to be present, the first count value is not less than one-third of the second count value, and the first count value is less than two-thirds of the second count value,

the processor further configured to identify a fifth button position as the location of the user input if the user input is determined to be present and the first count value is less than one-third of the second count value.

15. The apparatus according to claim 10, wherein at least one ratio range from the plurality of ratio ranges includes only one of an upper limit or a lower limit.

16. The apparatus according to claim 10, wherein the plurality of conductive traces includes a first conductive trace and a second conductive trace including two subtraces, wherein the first conductive trace is interleaved between the two subtraces of the second conductive trace and the first end of the first conductive trace is adjacent to the second end of the second conductive trace.

17. The apparatus according to claim 10, wherein the plurality of conductive traces includes a first conductive trace and a second conductive trace, wherein the first conductive trace is positioned alongside the second conductive trace such that the first end of the first conductive trace is adjacent to the second end of the second conductive trace.

18. The apparatus according to claim 10, wherein at least one of the plurality of conductive traces is made from a conductive polymer film.

19. An apparatus, comprising:

means for detecting a presence of a user input on one of five possible user input locations on a capacitive sensor array comprising two slider sensor elements and a guard sensor element; and

means for discriminating among five possible user input locations on the capacitive sensor array.

20. The apparatus according to claim 19, further comprising means for correlating a plurality of measured capacitance values from the capacitive sensor array with one of the five user input locations.