High-resolution electric field sensor in cover glass
A fingerprint sensor is described that includes a thin protective cover layer on a sensor glass layer with receive circuitry between the thin protective cover layer and the sensor glass layer. In an implementation, a fingerprint sensor assembly includes a controller; a metal layer configured to be electrically coupled to the controller; a transmit layer electrically connected to the metal layer and the controller; a sensor glass layer including at least one through-glass via, where the transmit layer is disposed on a first side of the sensor glass layer, and where the transmit layer is electrically coupled to the at least one through-glass via; a receive layer disposed on a second side of the sensor glass layer, where the receive layer is electrically coupled to the at least one through-glass via; and a protective cover layer disposed on the receive layer.
1. A fingerprint sensor assembly, comprising:
a controller;
a metal layer configured to be electrically coupled to the controller;
a transmit layer electrically connected to the metal layer and the controller, wherein the transmit layer is configured to transmit an electric field;
a sensor glass layer including at least one through-glass via, where the transmit layer is disposed on a first side of the sensor glass layer, and where the transmit layer is electrically coupled to the at least one through-glass via;
a receive layer disposed on a second side of the sensor glass layer, wherein the receive layer is electrically coupled to the at least one through-glass via and wherein the receive layer is configured to detect changes in the electric field; and
a protective cover layer disposed on the receive layer.
2. The fingerprint sensor assembly of claim 1 , wherein the protective cover layer includes aluminum oxide.
3. The fingerprint sensor assembly of claim 2 , wherein the aluminum oxide is about 1 μm in thickness.
4. The fingerprint sensor assembly of claim 1 , wherein the protective cover layer includes a single-crystal sapphire layer.
5. The fingerprint sensor assembly of claim 4 , wherein the single-crystal sapphire layer is between about 100 μm and 200 μm in thickness.
6. The fingerprint sensor assembly of claim 1 , wherein the protective cover layer includes silicon carbide.
7. The fingerprint sensor assembly of claim 1 , wherein the protective cover layer includes diamond.
8. The fingerprint sensor assembly of claim 1 , wherein at least one of the receive layer or the transmit layer includes indium tin oxide.
9. The fingerprint sensor assembly of claim 1 , wherein the at least one through-glass via includes a metal-filled blind via that extends from the first side of the sensor glass layer to the second side of the sensor glass layer, where the metal-filled blind via is configured to provide capacitive coupling between the transmit layer and the receive layer.
10. A cover glass assembly with a high-resolution electric field sensor, comprising:
a transmit layer electrically connected by a metal layer to a controller, wherein the transmit layer is configured to transmit an electric field;
a sensor glass layer including at least one through-glass via, where the transmit layer is disposed on a first side of the sensor glass layer and is electrically coupled to the at least one through-glass via;
a receive layer disposed on a second side of the sensor glass layer, where the receive layer is electrically coupled to the at least one through-glass via and wherein the receive layer is configured to detect changes in the electric field; and
a protective cover layer disposed on the receive layer,
where the cover glass assembly is configured to include a touch-panel device.
11. The cover glass assembly of claim 10 , where the controller is configured to image fingerprints.
12. The cover glass assembly of claim 10 , where the controller is configured to image a user's touch.
13. The cover glass assembly of claim 10 , where the protective cover layer includes aluminum oxide.
14. The cover glass assembly of claim 13 , wherein the aluminum oxide is about 1 μm in thickness.
15. The cover glass assembly of claim 10 , where the protective cover layer includes a single-crystal sapphire layer.
16. The cover glass assembly of claim 15 , wherein the single-crystal sapphire layer is between about 100 μm and 200 μm in thickness.
17. The cover glass assembly of claim 10 , where the protective cover layer includes silicon carbide.
18. The cover glass assembly of claim 10 , where the protective cover layer includes diamond.
19. A fingerprint-sensing mobile device, comprising:
a display assembly configured for a mobile device;
a transmit layer electrically connected by a metal layer to a controller, where the controller is electrically coupled to the display assembly, wherein the transmit layer is configured to transmit an electric field;
a sensor glass layer including at least one through-glass via, where the transmit layer is disposed on a first side of the sensor glass layer and is electrically coupled to the at least one through-glass via;
a receive layer disposed on a second side of the sensor glass layer, where the receive layer is electrically coupled to the at least one through-glass via and wherein the receive layer is configured to detect changes in the electric field; and
a protective cover layer disposed on the receive layer.
20. The fingerprint-sensing mobile device of claim 19 , where the display assembly includes a liquid crystal display.