Display Stack with Integrated Force Input Sensor

• US 20180224996A1
• Filed: 07/27/2017
• Published: 08/09/2018
• Est. Priority Date: 02/08/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Rad, Mohammad Reza Esmaeili, Ono, Shinya, Chang, Ting-Kuo
• Granted Patent: US 10,496,218 B2
• Time in Patent Office: Days
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: H10K 50/813 characterised by their shape
• CPC Class Codes: H10K 50/822 characterised by their shape
• CPC Class Codes: H10K 59/1201 Manufacture or treatment
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/40 OLEDs integrated with touch screens
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: H10K 77/10 Substrates, e.g. flexible substrates
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

A force input sensor can include a strain-sensitive region disposed as a meandering electrical trace onto a structural or functional layer of a display stack. In particular, the meandering electrical trace can include one or more diversions from a linear path, each diversion configured to increase the length of the electrical trace. A diversion can form a loop to increase the inductance of the meandering electrical trace; the inductance of the meandering electrical trace can be correlated to length of the inductive trace which, in turn, can be correlated to strain experienced by the structural or functional layer.

Claims

1. A organic light-emitting diode display stack layer comprising:

a substrate;

an anode disposed on the substrate; and

an electrical trace disposed on the substrate substantially circumscribing the anode, the electrical trace configured to couple to a force input sensor.

2. The organic light-emitting diode display stack layer of claim 1, wherein the anode is a member of a set of anodes disposed on the substrate.

3. The organic light-emitting diode display stack layer of claim 2, wherein:

the anode is first anode; and

the set of anodes further comprises a second anode adjacent to the first anode;

wherein

the electrical trace substantially circumscribes the second anode.

4. The organic light-emitting diode display stack layer of claim 3, wherein the electrical trace and the first anode define a first inductor loop and the electrical trace and the second anode define a second inductor loop in series with the first inductor loop.

5. The organic light-emitting diode display stack layer of claim 2, wherein the electrical trace forms a serpentine pattern at least partially traversing the substrate adjacent to each anode of the set of anodes.

6. The organic light-emitting diode displays tack layer of claim 2, wherein the electrical trace traverses a serpentine path along the substrate.

7. The organic light-emitting diode display stack layer of claim 6, wherein the electrical trace defines a series of inductor loop, each inductor loop substantially circumscribing a respective one anode of the set of anodes.

8. The organic light-emitting diode display stack layer of claim 1, wherein:

the substrate is transparent; and

the anode is formed from an optically transparent, electrically conductive material.

9. The organic light-emitting diode displays tack layer of claim 7, wherein the anode is formed from the same material as the electrical trace.

10. A display configured to receive force input, the display comprising:

a display stack comprising;

a substrate defining an active display region of the display;

a grid of patterned electrical traces disposed on the substrate; and

a force input sensor coupled to each patterned electrical trace of the grid of patterned electrical traces, the force input sensor configured to correlate an electrical property of at least one patterned electrical trace to a magnitude of force applied to the display.

11. The display of claim 10, wherein:

the display stack is an organic light-emitting diode display stack and further comprises;

an array of pixels within the active display region, each pixel comprising;

an anode coupled to the substrate;

a light-emitting element coupled to the anode; and

a cathode coupled to the light-emitting element; and

each patterned electrical trace of the grid of patterned electrical traces is configured to substantially circumscribe at least one anode of at least one pixel, thereby defining at least one inductor loop.

12. The display of claim 11, wherein the electrical property is inductance or reactance.

13. The display of claim 10, wherein at least one patterned electrical trace of the grid of patterned electrical traces follows a serpentine pattern.

14. The display of claim 10, wherein the electrical property is resistance and each patterned electrical trace of the grid of patterned electrical traces is formed from a peizoresistive material.

15. A method for detecting force input with a display, the method comprising:

deactivating a pixel;

causing a conductive element of the pixel to float with respect to a system ground;

applying a drive signal to an input lead of an electrical trace at least partially circumscribing the conductive element;

measuring an electrical property of the electrical trace based on a sense signal received from an output lead of the electrical trace;

correlating the measurement to a strain experienced by the electrical trace; and

correlating the strain to an input force applied to the display.

16. The method of claim 15, wherein the electrical property is one of resistance or inductance.

17. The method of claim 15, wherein:

the electrical property is inductance; and

the drive signal comprises an alternating current component.

18. The method of claim 17, wherein measuring an electrical property comprises determining a phase difference between the drive signal and the sense signal.

19. The method of claim 15, wherein correlating the measurement to the strain comprises accessing a relational database.

20. The method of claim 15, wherein the display comprises an organic light-emitting diode display stack and the conductive element comprises an anode of the pixel.