Capacitive sensing apparatus designs

• US 7,218,124 B1
• Filed: 01/30/2006
• Issued: 05/15/2007
• Est. Priority Date: 01/30/2006
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Mackey, Bob Lee, Golovchenko, Mykola
• Primary Examiner(s): Hirshfeld; Andrew H.
• Assistant Examiner(s): Dole; Timothy J.
• Application Number:
  US11/343,452
• Time in Patent Office: 470 Days
• Field of Search: 324/660, 324/663, 324/686
• US Class Current: 324/660
• CPC Class Codes: G01D 5/2415 adapted for encoders

Abstract

One type of capacitive sensing apparatus has a sensing element that includes a first portion and a second portion adjacent opposite edges of a sensing region. Signals from the first and second portions are combined. Another type of apparatus includes: a first sensing element including first and second portions; a second sensing element including third and fourth portions; and a third sensing element including fifth and sixth portions. The first, third and fifth portions form a first pattern, and the second, fourth and sixth portions form a second pattern. The patterns are bilaterally symmetrical about a median of a sensing region. In another type of apparatus, an electrical conductor coupled to a first sensing element passes through a gap in a second sensing element. An electrical conductor coupled to the second sensing element is dimensioned such that a capacitive coupling to the second sensing element is compensated for the gap.

Claims

1. A capacitive sensing apparatus comprising:

a first sensing element; and

a second sensing element having a first gap, wherein a first electrical conductor coupled to said first sensing element passes through said first gap and wherein a second electrical conductor coupled to said second sensing element is dimensioned such that a capacitive coupling to said second sensing element is compensated for said first gap.

2. The capacitive sensing apparatus of claim 1 wherein an areal measure of said second electrical conductor is substantially equal to an areal measure of said first gap.

3. The capacitive sensing apparatus of claim 1 further comprising a third sensing element having a second gap, wherein said first and second electrical conductors pass through said second gap and wherein a third electrical conductor coupled to said third sensing element is dimensioned such that a capacitive coupling to said third sensing element is compensated for said second gap.

4. The capacitive sensing apparatus of claim 3 wherein said first and third electrical conductors are connected to each other to combine a sensor signal output from said first sensing element and a sensor signal output from said third sensing element.

5. The capacitive sensing apparatus of claim 3 wherein a measure of a sensor signal output from said first sensing element is added to a measure of a sensor signal output from said third sensing element to provide a combined output signal.

6. The capacitive sensing apparatus of claim 1 wherein said first and second sensing elements have widths that vary and lengths that traverse a sensing region.

7. The capacitive sensing apparatus of claim 6 further comprising circuitry coupled to said plurality of sensing elements, said circuitry operable to use signals output by said first and second sensing elements to determine an unambiguous position along an axis in the lengthwise dimension of said sensing region.

8. The capacitive sensing apparatus of claim 7 wherein said position is also determined along an axis in the widthwise dimension of said sensing region.

9. The capacitive sensing apparatus of claim 6 further comprising circuitry coupled to said plurality of sensing elements, said circuitry operable to use signals output by said first and second sensing elements to determine a rate of movement of an object proximate to said sensing region.

10. The capacitive sensing apparatus of claim 6 wherein said sensing region is ring-shaped.

11. The capacitive sensing apparatus of claim 6 wherein said sensing region is rectilinear in shape.