Fingerprint sensors for mobile devices
Various embodiments concern fingerprint sensors for mobile devices. By modifying one or more layers of a display assembly, a fingerprint sensor can be positioned directly beneath the display. For example, the air gap within the backlight structure could be replaced by an optically clear adhesive that allows waves emitted by a fingerprint sensor to properly propagate through the display assembly. In some embodiments, a fingerprint sensor is set within a recess in the display assembly. For example, a depression could be created in the protective substrate, and the fingerprint sensor could be set within the depression using an optically clear adhesive. The functionality of a fingerprint sensor could also be replicated by increasing the density of touch-sensing elements in certain areas of a display assembly that utilizes in-cell technology.
1. A display assembly comprising:
a display panel;
a backlight assembly located below the display panel that includes
a backlight configured to generate light that illuminates the display panel,
an optically clear adhesive layer disposed between the backlight and a diffuser,
wherein the optically clear adhesive layer substantially eliminates an air gap between the backlight and the diffuser, and
the diffuser configured to diffuse the light emitted toward the display panel by the backlight; and
a fingerprint sensor located below the backlight assembly.
2. The display assembly of claim 1 , wherein the display panel is a liquid crystal display (LCD) panel.
3. The display assembly of claim 1 , further comprising:
a protective substrate located above the display panel.
4. The display assembly of claim 3 , wherein the protective substrate is comprised of glass.
5. The display assembly of claim 1 , further comprising:
touch circuitry that generates a signal responsive to a user interaction with the display assembly.
6. The display assembly of claim 5 , wherein the touch circuitry is located above the display panel.
7. The display assembly of claim 5 , wherein the touch circuitry is affixed to a mounting substrate that is directly adjacent to the display panel.
8. The display assembly of claim 1 , wherein elimination of the air gap reduces reflection and refraction of waves emitted by the fingerprint sensor as the waves propagate through the display assembly.
9. The display assembly of claim 1 , wherein the fingerprint sensor is an ultrasonic fingerprint sensor.
10. The display assembly of claim 1 , wherein the optically clear adhesive layer comprises an acrylic-based adhesive or a silicone-based adhesive.
11. A display assembly comprising:
a protective substrate having
an outward-facing side with which a user makes contact during an interaction with the display assembly, and
an inward-facing side having a depression formed therein; and
a substantially transparent fingerprint sensor that is set within the depression.
12. The display assembly of claim 11 , further comprising:
touch circuitry located below the protective substrate, the touch circuitry being configured to generate a signal responsive to a user interaction with the outward-facing side of the protective substrate.
13. The display assembly of claim 11 , wherein the substantially transparent fingerprint sensor is an ultrasonic sensor, an optical sensor, a radio frequency (RF) sensor, a thermal sensor, a capacitive sensor, or a combination thereof.
14. The display assembly of claim 11 , wherein the substantially transparent fingerprint sensor is affixed within the depression using an optically clear adhesive.
15. The display assembly of claim 14 , wherein the optically clear adhesive comprises an acrylic-based adhesive or a silicone-based adhesive.
16. A method comprising:
acquiring a protective substrate to be used in a display assembly,
wherein the protective substrate includes
an outward-facing side with which a user makes contact during an interaction with the display assembly, and
an inward-facing side;
forming a depression on the inward-facing side of the protective substrate;
setting a substantially transparent fingerprint sensor within the depression; and
affixing the substantially transparent fingerprint sensor within the depression using an optically clear adhesive.
17. The method of claim 16 , wherein the optically clear adhesive is indium-tin-oxide (ITO).
18. The method of claim 16 , wherein the protective substrate is comprised of glass, plastic, or crystallized aluminum oxide.
19. The method of claim 16 , wherein the protective substrate includes multiple substrate layers having an adhesive layer interposed between each pair of substrate layers.
20. A display assembly comprising:
a protective substrate; and
an integrated display panel located below the protective substrate,
wherein the integrated display panel is divided into a plurality of cells that include display elements, touch-sensing elements, or a combination thereof,
wherein the plurality of cells includes
a first cell having a first count of touch-sensing elements, and
a second cell having a second count of touch-sensing elements sufficient to simulate the functionality of a fingerprint scanner, and
wherein the first count and the second count are different values.
21. The display assembly of claim 20 , wherein the display elements are liquid crystals.
22. The display assembly of claim 20 , wherein the touch-sensing elements are capacitors.
23. The display assembly of claim 22 , wherein each capacitor is configured to generate a signal responsive to determining a user has made contact with the protective substrate directly above the corresponding capacitor.
24. The display assembly of claim 20 , further comprising:
touch circuitry for analyzing signals generated by the touch-sensing elements responsive to a user interaction with the protective substrate; and
display circuitry for generating signals to control the display elements,
wherein the touch circuitry and the display circuitry are included on a printed circuit board assembly.
25. The display assembly of claim 20 , wherein cells expected to be the subject of frequent user interactions include a higher density of touch-sensing elements compared to other cells.
26. The display assembly of claim 20 , further comprising:
a processor configured to
monitor whether a user has placed a finger on the second cell;
responsive to determining that the user placed the finger on at least a portion of the second cell,
generate, by each touch-sensing element located within the at least a portion of the second cell, a signal based on which part of the finger is directly above the corresponding touch-sensing element; and
processing the signals to determine whether the finger matches a fingerprint stored in a memory accessible to a user device of which the display assembly is a part.
27. The display assembly of claim 26 , wherein the memory is housed within the user device.
28. The display assembly of claim 26 , wherein the memory is accessible to the user device via a connection across a network.