Biometric sensor stack structure
Various structures and methods are disclosed for packaging a biometric sensor, such as a capacitive biometric sensor. Embodiments incorporate various placements of the biometric sensor, structure surrounding a biometric sensor, connection structures (electrical, physical, or both), and techniques for enhanced sensor imaging, sensor retention, and guiding a user's finger to a proper location above a biometric sensor. For example, A biometric sensor assembly can include an aperture formed in a trim with a cap disposed in the aperture. A biometric sensor may be positioned below the cap and a switch positioned below the biometric sensor.
1. An electronic device, comprising:
a trim defining an aperture;
a cap disposed in the aperture;
a rigid biometric sensor coupled to a bottom surface of the cap;
a stiffening plate coupled to the trim below the cap, wherein a space is defined between the rigid biometric sensor and the stiffening plate; and
a switch positioned below the stiffening plate; wherein:
at least the cap, the stiffening plate, and the sensor are configured to move downward when a force is exerted on an outer surface of the cap.
2. The electronic device as in claim 1 , wherein the cap, the biometric sensor, and the trim are configured to move downward when the force is exerted on the outer surface of the cap.
3. The electronic device as in claim 1 , wherein the biometric sensor is stacked vertically below the cap and the switch is stacked vertically below the biometric sensor.
4. The electronic device as in claim 1 , further comprising a cover glass extending across a surface of the electronic device.
5. The electronic device as in claim 4 , wherein the cap is positioned in a button hole in the cover glass and the cap is raised above an outer surface of the cover glass.
6. The electronic device as in claim 5 , wherein the trim surrounding the cap is positioned in the button hole and is raised above the outer surface of the cover glass.
7. The electronic device as in claim 4 , wherein the cap is positioned in a button hole in the cover glass and the cap is recessed below an outer surface of the cover glass.
8. The electronic device as in claim 7 , wherein the trim surrounding the cap is configured as a chamfer between the trim and an outer surface of the cap.
9. The electronic device as in claim 1 , wherein the trim electrically isolates the biometric sensor.
10. A method for operating a biometric sensor stack in an electronic device, wherein the biometric sensor stack comprises a structure surrounding a cap, a rigid biometric sensor positioned below the cap, a stiffening plate below the cap and set apart from at least the rigid biometric sensor by a space, and a switch positioned below the biometric sensor, the method comprising:
capturing biometric data using the biometric sensor when an external object is grounded by at least a portion of the structure surrounding the cap; and
signaling an input to the electronic device by activating the switch based on a downward movement of at least the cap, the stiffening plate, and the biometric sensor when a force is exerted on the cap.
11. The method as in claim 10 , further comprising capturing biometric data immediately before the biometric sensor begins moving.
12. The method as in claim 10 , further comprising capturing biometric data immediately after the biometric sensor stops moving.
13. The method as in claim 10 , wherein the biometric sensor comprises a fingerprint sensor.
14. The method as in claim 10 , wherein capturing biometric data comprises capturing biometric data from one or more fingers when the biometric sensor stack is moving.
15. The method as in claim 10 , wherein signaling an input to the electronic device by activating the switch based on a downward movement of the biometric sensor stack comprises signaling an input to the electronic device by collapsing the switch based on the downward movement of the biometric sensor stack.
16. The method of claim 10 , wherein the rigid biometric sensor is not compressed between the cap and the stiffening plate when the force is exerted on the cap.