Embedded Force Measurement

• US 20150103050A1
• Filed: 12/19/2014
• Published: 04/16/2015
• Est. Priority Date: 11/29/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Lynch, Stephen Brian, Rappoport, Benjamin Mark, Rothkopf, Fletcher R., Drzaic, Paul Stephen, Myers, Scott Andrew
• Granted Patent: US 9,746,983 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 1/1643 the display being associated to a digitizer, e.g. laptops that can be used as penpads details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615
• CPC Class Codes: G06F 1/1652 the display being flexible, e.g. mimicking a sheet of paper, or rollable
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04144 using an array of force sensing means position sensing using the local deformation of sensor cells G06F3/0447
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

Disclosed embodiments relate to a force detection system that detects force exerted on a flexible display based upon changes in resistance and/or capacitance. In one embodiment, a method includes measuring a baseline comprising a baseline resistance or a baseline capacitance or both of a force measurement layer disposed within or overlaid on the display panel. The method further includes detecting a change in the baseline resistance or the baseline capacitance or both and calculating a change location where the change in the baseline resistance or the baseline capacitance or both occurred. The method also includes calculating a magnitude of the change in the baseline resistance or the baseline capacitance or both.

Claims

1. A force detection system, comprising:

a display comprising flexible regions;

a force measurement layer disposed on or in the display, having an attribute with a baseline measurement;

force measurement circuitry configured to determine the baseline measurement of the force measurement layer, detect a change in the baseline measurement in at least one portion of the force measurement layer, store change information relating to the change in the baseline measurement, and calculate a force input location based upon the change information.

2. The force detection system of claim 1, wherein the display comprises a cover layer that comprises thinned regions configured to provide increased flexibility to the flexible regions.

3. The force detection system of claim 2, wherein the thinned regions are located in regions of the display where touch inputs are likely to occur.

4. The force detection system of claim 1, wherein the force measurement layer comprises one or more strain gauges that decrease in resistance when compressed.

5. The force detection system of claim 1, wherein the force measurement layer comprises one or more thin film plates that vary in capacitance when force is applied.

6. The force detection system of claim 1, wherein the baseline measurement comprises a baseline resistance measurement, and wherein the force measurement circuitry is configured to detect a change in the baseline resistance measurement of an order of micro-ohms.

7. The force detection system of claim 1, wherein the force measurement system stores a location and a magnitude of change in resistance and calculates the force input location based upon the location of the change in a baseline resistance.

8. The force detection system of claim 1, wherein the force measurement system stores a location and a magnitude of change in resistance and calculates a magnitude of force input location based upon the magnitude of the change in the baseline resistance.

9. The force detection system of claim 1, wherein the force measurement layer comprises an array of rows and columns of crossing conductive wires.

10. An electronic device, comprising:

a display;

a force measurement layer disposed in or on the display, having an attribute with a baseline measurement; and

processing circuitry configured to;

detect a variation from the baseline measurement in the force measurement layer;

associate a location of the variation from the baseline measurement with a force input location after detecting the variation from the baseline measurement in the force measurement layer;

associate a magnitude of the variation from the baseline attribute with a magnitude of a force input; and

provide a graphical output to the display that depends on the force input location and the magnitude of force.

11. The electronic device of claim 10, wherein the display is configured to provide a graphical user interface of the electronic device.

12. The electronic device of claim 10, wherein the display comprises one or more flexible regions configured to add flexibility to the display.

13. The electronic device of claim 10, wherein the display comprises an organic light-emitting diode display.

14. An electronic device, comprising:

a display;

a force measurement layer disposed on or in the display, wherein the force measurement layer comprises an array of rows and columns of crossing conductive lines;

force measurement circuitry configured to determine a baseline measurement of the force measurement layer, wherein the baseline measurement changes when a distance between at least two of the conductive lines changes.

15. The electronic device defined in claim 14, wherein the rows of conductive lines are located in a first plane, wherein the columns of conductive lines are located in a second plane that is different than the first plane, wherein the rows and columns of conductive lines do not contact each other unless a force is applied to the force measurement layer.

16. The electronic device defined in claim 14, wherein the conductive lines comprise conductive wires that have a diameter of about 10 microns.

17. The electronic device defined in claim 14, wherein the rows of conductive lines are spaced within 70 microns of each other.

18. The electronic device defined in claim 14, wherein the force measurement circuitry determines a baseline resistance of the array of rows and columns of crossing conductive lines.

19. The electronic device defined in claim 18, further comprising a low frequency filter that filters the baseline resistance, wherein the low frequency filter filters variations in the resistance of the array of rows and columns of crossing conductive lines that arise from temperature changes.

20. The electronic device defined in claim 14, wherein the conductive lines comprise a conductive nanoscale material.