Method and apparatus for implementing a capacitive touch slider

• US 8,179,380 B2
• Filed: 12/19/2008
• Issued: 05/15/2012
• Est. Priority Date: 12/19/2008
• Status: Active Grant

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Ellis, John
• Primary Examiner(s): Olson, Jason
• Application Number:
  US12/339,776
• Publication Number:
  US 20100156839A1
• Time in Patent Office: 1,243 Days
• Field of Search: None
• US Class Current: 345/174
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/96066 Thumbwheel, potentiometer, scrollbar or slider simulation by touch switch

Abstract

A capacitive touch slider array comprises a first conductive trace associated with a first sensing node. The first conductive trace includes a first conductive line and a plurality of first conductive fingers extending from the first conductive line. The plurality of first conductive fingers have lengths that increase from a first end of the capacitive touch slider array to a second end of the capacitive touch slider array. A second conductive trace associated with a second sensing node includes a second conductive line and a plurality of second conductive fingers extending from the second conductive line. The plurality of second conductive fingers have lengths that increase from the second end of the capacitive touch slider array to the first end of the capacitive touch slider array.

Claims

1. A capacitive touch slider array, comprising:

a first conductive trace associated with a first sensing node, the first conductive trace including a first conductive line and a plurality of first conductive fingers extending from the first conductive line, the plurality of first conductive fingers having lengths that increase from a first end of the capacitive touch slider array to a second end of the capacitive touch slider array;

a second conductive trace associated with a second sensing node, the second conductive trace including a second conductive line and a plurality of second conductive fingers extending from the second conductive line, the plurality of second conductive fingers having lengths that increase from the second end of the capacitive touch slider array to the first end of the capacitive touch slider array; and

a third conductive trace associated with a ground node, the third conductive trace interleaved between the first plurality of conductive fingers and the second plurality of conductive fingers.

2. The capacitive touch slider array of claim 1, wherein each of the first plurality of conductive fingers are in a same axis as a particular one of the second plurality of conductive fingers.

3. The capacitive touch slider array of claim 1, further including:

a first capacitive sensor located at the first end of the capacitive touch slider array; and

a second capacitive sensor located at the second end of the capacitive touch slider array.

4. The capacitive touch slider array of claim 1, wherein each position between the first end and the second end of the capacitive touch slider array has a unique ratio of capacitance of the first sensing node to the second sensing node responsive to a conductive element contacting a position on the capacitive slider array.

5. The capacitive touch slider array of claim 1, wherein a geometry of the first and second conductive traces is shaped to provide a two-dimensional position detection capability.

6. The capacitive touch slider array of claim 1, wherein a geometry of the first and second conductive traces is shaped into at least one of an arc or circle.

7. A capacitive touch slider array, comprising:

a first conductive trace associated with a first sensing node, the first conductive trace including a first conductive line and a plurality of first conductive fingers extending from the first conductive line, the plurality of first conductive fingers having lengths that increase from a first end of the capacitive touch slider array to a second end of the capacitive touch slider array;

a second conductive trace associated with a second sensing node, the second conductive trace including a second conductive line and a plurality of second conductive fingers extending from the second conductive line, the plurality of second conductive fingers having lengths that increase from the second end of the capacitive touch slider array to the first end of the capacitive touch slider array;

a third conductive trace associated with a ground node, the third conductive trace interleaved between the first plurality of conductive fingers and the second plurality of conductive fingers;

a first capacitive sensor located at the first end of the capacitive touch slider array; and

a second capacitive sensor located at the second end of the capacitive touch slider array.

8. The capacitive touch slider array of claim 7, wherein each of the first plurality of conductive fingers are in a same axis as a particular one of the second plurality of conductive fingers.

9. The capacitive touch slider array of claim 7, wherein each position between the first end and the second end of the capacitive touch slider array has a unique ratio of capacitance of the first sensing node to the second sensing node responsive to a conductive element contacting a position on the capacitive slider array.

10. The capacitive touch slider array of claim 7, wherein a geometry of the first and second conductive traces is shaped to provide a two-dimensional position detection capability.

11. The capacitive touch slider array of claim 7, wherein a geometry of the first and second conductive traces is shaped into at least one of an arc or circle.

12. A method for determining a position of a conducting element on a capacitive touch slider array, comprising the steps of:

sensing a capacitance at a first node and a second node associated with the capacitive touch slider array, the first node associated with a first conductive trace having a first plurality of conductive fingers, the second node associated with a second conductive trace having a second plurality of conductive fingers, and a third conductive trace associated with a ground node, the third conductive trace interleaved between the first plurality of conductive fingers and the second plurality of conductive fingers;

calculating a ratio using capacitances associated with the first node and the second node; and

determining the position of the conductive element on the capacitive touch slider array responsive to the calculated ratio.

13. The method of claim 12, further including the step of determining if a capacitive sensor associated with an end of the capacitive touch slider array has been actuated.

14. The method of claim 12, wherein the step of determining the position further comprises the step of determining the position of the conductive element on the capacitive touch slider array responsive to the calculated ratio and an indication that the capacitive sensor associated with an end of the capacitive touch slider array has been actuated.

15. The method of claim 13, wherein the step of determining if the capacitive sensor has been actuated further comprises the steps of:

comparing the sensed capacitance at the capacitive sensor with a predetermined threshold value;

determining if the sensed capacitance at the capacitive sensor is greater than the predetermined threshold value; and

determining that the capacitive sensor is actuated if the sensed capacitance is greater than the predetermined threshold value.

16. The method of claim 12, wherein the step of calculating further includes the steps of:

comparing the sensed capacitance at the first node and the second node with predetermined threshold values;

determining if the sensed capacitance at the first node and the second node are greater than the predetermined threshold values; and

calculating the ratio using the capacitances associated with the first node and the second node if the sensed capacitances at the first node and the second node are greater than the predetermined threshold values.

17. The method of claim 16, further including the step of subtracting a minimum touched ratio from the calculated ratio.