Capacitive sensor

• US 9,423,418 B2
• Filed: 02/25/2013
• Issued: 08/23/2016
• Est. Priority Date: 02/25/2013
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Alameh, Rachid M, Cauwels, Patrick J, Emmert, Steve C, Paitl, Kenneth A
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): NGUYEN, TRUNG Q
• Application Number:
  US13/776,103
• Publication Number:
  US 20140239984A1
• Time in Patent Office: 1,275 Days
• Field of Search: 324686-688, 324/600, 324/548, 324/519, 324/500, 324/522
• US Class Current: 1/1
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01R 1/04 Housings; Supporting members; Arrangements of terminals
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 2217/960765 Details of shielding arrangements

Abstract

One example disclosed wearable device includes a first housing portion having a conductive section and a non-conductive section. The conductive section is connected to ground. A second housing portion includes a printed circuit board (PCB) with a conductor on the PCB surface positioned beneath the non-conductive section. The conductor on the PCB surface and the conductive section form a capacitor of a capacitive sensor. The wearable device may also include a first adhesive layer between a surface of the non-conductive section of the first housing portion and the PCB surface. A second adhesive layer, coplanar with the first adhesive layer, may be applied between a surface of the conductive section of the first housing portion and the PCB surface. The first adhesive layer and the second adhesive layer form a water tight seal that prevents liquids from penetrating into at least the second housing portion.

Claims

1. A wearable device, comprising:

a first housing portion having a conductive section and a non-conductive section, the conductive section being connected to ground;

a second housing portion including a printed circuit board with a conductor on the printed circuit board surface positioned beneath the non-conductive section of the first housing portion, the conductor on the printed circuit board surface and the conductive section of the first housing portion forming a capacitor of a capacitive sensor; and

capacitive sensor circuitry, operatively coupled to the conductor on the printed circuit board surface, wherein the capacitive sensor circuitry drives a voltage of the conductor on the printed circuit board surface to create a capacitive charge between the conductor on the printed circuit board surface and the conductive section of the first housing portion.

2. The wearable device of claim 1, further comprising:

a first adhesive layer between a surface of the non-conductive section of the first housing portion and the printed circuit board surface.

3. The wearable device of claim 2, further comprising:

a second adhesive layer, coplanar with the first adhesive layer, between a surface of the conductive section of the first housing portion and the printed circuit board surface.

4. The wearable device of claim 3, wherein the first adhesive layer and the second adhesive layer form a water tight seal that prevents liquids from penetrating into at least the second housing portion.

5. The wearable device of claim 4, further comprising:

a tolerance gap between adjacent edges of the first adhesive layer and the coplanar second adhesive layer, the tolerance gap allowing coplanar expansion of the first adhesive layer or the second adhesive layer due to temperature or pressure.

6. The wearable device of claim 1, further comprising:

a conductive shield, formed as a layer of the printed circuit board.

7. The wearable device of claim 1, wherein the capacitive sensor circuitry further drives a shield layer of the printed circuit board to the same voltage as the conductor on the printed circuit board surface.

8. The wearable device of claim 1, wherein the first housing portion conductive section comprises a cutout or bore and wherein the non-conductive section is fitted within the cutout or bore of the conductive section.

9. The wearable device of claim 8, wherein the non-conductive section has an interference fit with the cutout or bore of the first housing portion conductive section.

10. The wearable device of claim 8, further comprising:

a non-conductive insulator between an outer perimeter of the non-conductive section and the conductive section.

11. The wearable device of claim 10, wherein the non-conductive insulator is a grommet comprising a t-shaped cross-section.

12. The wearable device of claim 10, wherein the grommet further comprises:

an axially extending cylindrical portion; and

a radial disc portion connected to the axially extending cylindrical portion.

13. A wearable device, comprising:

a first housing portion having first and second conductive sections separated by a non-conductive insulator, with the first conductive section being connected to ground;

a second housing portion including a printed circuit board, the second conductive section operatively coupled to the printed circuit board, the first and second conductive sections forming a capacitor of a capacitive sensor; and

capacitive sensor circuitry, operatively coupled to the printed circuit board surface, wherein the capacitive sensor circuitry drives a voltage of the second conductive section to create a capacitive charge between the second conductive section and the first conductive section of the first housing portion.

14. The wearable device of claim 13, wherein the first housing portion comprises a cutout or bore within the first conductive section and the second conductive section is fitted within the cutout or bore of the first conductive section;

and

wherein the non-conductive insulator surrounds an outer perimeter of the second conductive section.

15. A wearable device comprising:

a first non-conductive housing portion;

a second housing portion including a printed circuit board with a conductor on the printed circuit board surface positioned beneath the non-conductive housing portion;

a ground conductor, the conductor on the printed circuit board surface and the ground conductor forming a capacitor of a capacitive sensor; and

capacitive sensor circuitry, operatively coupled to the conductor on the printed circuit board surface, wherein the capacitive sensor circuitry drives a voltage of the conductor on the printed circuit board surface to create a capacitive charge between the conductor on the printed circuit board surface and the ground conductor.

16. The wearable device of claim 15, wherein the ground conductor is positioned on an outer surface of the first non-conductive housing portion.

17. The wearable device of claim 15, further comprising:

a wristband segment connected to the second housing portion, where the ground conductor is positioned on the wristband segment.

18. A wearable device, comprising:

a first wristband segment;

a second wristband segment, wherein the first wristband segment and the second wristband segment are connected to a housing of the wearable device;

a first conductor positioned on the first wristband segment;

a second conductor positioned on the second wristband segment, the first conductor and the second conductor forming a capacitor of a capacitive sensor; and

capacitive sensor circuitry, operatively coupled to the first conductor, wherein the capacitive sensor circuitry drives a voltage of the first conductor to create a capacitive charge between the first conductor and the second conductor.

19. A wearable device, comprising:

a housing having a wristband connected to the housing;

a first conductor positioned on the wristband and a second conductor positioned on the housing, the first conductor and the second conductor forming a capacitor of a capacitive sensor; and

capacitive sensor circuitry, operatively coupled to the second conductor on the housing, wherein the capacitive sensor circuitry drives a voltage of the second conductor on the housing to create a capacitive charge between the second conductor on the housing surface and the first conductor on the wristband.