Capacitive sensing using a repeated pattern of sensing elements

• US 7,545,289 B2
• Filed: 07/17/2006
• Issued: 06/09/2009
• Est. Priority Date: 07/17/2006
• Status: Expired due to Fees

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Mackey, Bob Lee, Golovchenko, Mykola
• Primary Examiner(s): WONG, ALBERT KANG
• Application Number:
  US11/488,742
• Publication Number:
  US 20080024329A1
• Time in Patent Office: 1,058 Days
• Field of Search: 341/20, 341/22, 341/33, 345/173, 345/168, 324/660, 324/658, 324/678, 178/18.01, 178/18.06
• US Class Current: 341/20
• CPC Class Codes: G01D 5/2415 adapted for encoders

Abstract

A repeated pattern of sensing elements can be used to indicate an unambiguous position along an axis in a sensing region. For example, different-sized sensing elements can be arranged in a repeating pattern, and the relative measures of their respective output signals can be used to identify a position in the sensing region.

Claims

1. A capacitance sensing apparatus for sensing an object proximate to a sensing region, said apparatus comprising:

a plurality of different-sized first sensing elements coupled to a first electrical conductor, wherein a first measure of a sensor signal output on said first electrical conductor corresponds at least in part to the size of a first sensing element proximate to said object;

a plurality of different-sized second sensing elements coupled to a second electrical conductor, wherein a second measure of a sensor signal output on said second electrical conductor corresponds at least in part to the size of a second sensing element proximate to said object; and

a plurality of different-sized third sensing elements coupled to a third electrical conductor, wherein a third measure of a sensor signal output on said third electrical conductor corresponds at least in part to the size of a third sensing element proximate to said object;

wherein said first sensing elements, said second sensing elements and said third sensing elements are arranged stripe-like in a repeating pattern along an axis in said sensing region and wherein said first, second and third measures together indicate an unambiguous position along said axis.

2. The apparatus of claim 1 wherein said repeating pattern comprises in order:

a one of said first sensing elements;

a one of said second sensing elements; and

a one of said third sensing elements.

3. The apparatus of claim 1 wherein said repeating pattern comprises in order:

a one of said first sensing elements;

a one of said third sensing elements;

a one of said second sensing elements; and

another one of said third sensing elements.

4. The apparatus of claim 1 wherein said sensing region comprises a plurality of non-overlapping sub-regions, each of said sub-regions comprising:

a plurality of contiguous sensing elements comprising a number of said first sensing elements, a number of said second sensing elements, and a number of said third sensing elements; and

a segment of each of said first, second and third electrical conductors;

wherein total capacitance within each of said sub-regions, if measured in the absence of an object proximate to said sensing region, is approximately equal for each of said sub-regions.

5. The apparatus of claim 1 wherein said sensing region comprises a plurality of non-overlapping sub-regions, each of said sub-regions comprising a plurality of contiguous sensing elements comprising a number of said first sensing elements, a number of said second sensing elements, and a number of said third sensing elements;

wherein said sub-regions are each approximately equal in width, wherein width is measured in the direction of said axis.

6. The apparatus of claim 1 wherein said first sensing elements comprise elements having different widths, said second sensing elements comprise elements having different widths, and said third sensing elements comprise elements having different widths.

7. The apparatus of claim 1 wherein said first sensing elements comprise elements having different lengths and said second sensing elements comprise elements having different lengths.

8. The apparatus of claim 1 wherein said first, second and third sensing elements vary in depth relative to a surface of said sensing region.

9. The apparatus of claim 1 wherein said third electrical conductor varies in size according to the different sizes of said first and second sensing elements.

10. A method of sensing an object proximate to a sensing region, said method comprising:

receiving a first measure of a sensor signal that is output on a first electrical conductor coupled to a plurality of different-sized first sensing elements, wherein said first measure corresponds to the sizes of said first sensing elements in sensing range of said object;

receiving a second measure of a sensor signal that is output on a second electrical conductor coupled to a plurality of different-sized second sensing elements, wherein said second measure corresponds to the sizes of said second sensing elements in sensing range of said object;

receiving a third measure of a sensor signal that is output on a third electrical conductor coupled to a plurality of different-sized third sensing elements, wherein said third measure corresponds to the sizes of said third sensing elements in sensing range of said object, wherein said first sensing elements, said second sensing elements and said third sensing elements are arranged stripe-like in a repeating pattern along an axis in said sensing region; and

identifying an unambiguous position along said axis using said first, second and third measures.

11. The method of claim 10 wherein said repeating pattern comprises, in order, a one of said first sensing elements, a one of said second sensing elements, and a one of said third sensing elements.

12. The method of claim 10 wherein said repeating pattern comprises, in order, a one of said first sensing elements, a one of said third sensing elements, a one of said second sensing elements, and another one of said third sensing elements.

13. The method of claim 10 wherein said sensing region comprises a plurality of non-overlapping sub-regions, each of said sub-regions comprising:

a plurality of contiguous sensing elements comprising a number of said first sensing elements, a number of said second sensing elements, and a number of said third sensing elements; and

a segment of each of said first, second and third electrical conductors;

wherein total capacitance within each of said sub-regions, if measured in the absence of an object proximate to said sensing region, is approximately equal for each of said sub-regions.

14. The method of claim 10 wherein said sensing region comprises a plurality of non-overlapping sub-regions, each of said sub-regions comprising a plurality of contiguous sensing elements comprising a number of said first sensing elements, a number of said second sensing elements, and a number of said third sensing elements;

wherein said sub-regions are each approximately equal in width, wherein width is measured in the direction of said axis.

15. The method of claim 10 wherein said first sensing elements comprise elements having different widths, said second sensing elements comprise elements having different widths, and said third sensing elements comprise elements having different widths.

16. The method of claim 10 wherein said third electrical conductor has a width that varies according to the different sizes of said first and second sensing elements.

17. The method of claim 10 wherein said first sensing elements comprise elements having different lengths and said second sensing elements comprise elements having different lengths.

18. The method of claim 10 wherein said first, second and third sensing elements vary in depth relative to a surface of said sensing region.