Touchpad force calculation
AssigneeMicrosoft Technology Licensing, LLC
InventorsFederico Zannier, Lalit Anil Palve, Rhishikesh Ashok Sathe
Life of this patent
Estimating the term…
Abstract
Methods for estimating a force F exerted on a touchpad are disclosed. In one example, a force sensing touchpad comprises a printed circuit board (PCB) comprising four PCB electrodes and a spring spaced from the PCB and comprising four spring electrodes. Changes in capacitance at two of the PCB electrodes are determined and used to calculate a first local gradient between the two electrodes. Changes in capacitance at the other two PCB electrodes are determined and used to calculate a second local gradient between these two electrodes. The local gradients are used to calculate local forces at each PCB electrode, and the local forces are used to calculate the force F exerted on the touchpad.
Claims20
A method for estimating a force F exerted on a touchpad in a computing device, the touchpad comprising a printed circuit board (PCB) comprising four PCB electrodes and a spring spaced from the PCB and comprising four spring electrodes, the spring mounted on a base plate, wherein a first current distance between the PCB and the base plate at a first PCB electrode of the four PCB electrodes is d01, the first PCB electrode is spaced from a first spring electrode of the four spring electrodes by a first distance d1, a second PCB electrode of the four PCB electrodes is spaced from a second spring electrode of the four spring electrodes by approximately the first distance d1, a second current distance between the PCB and the base plate at a third PCB electrode of the four PCB electrodes is d02, the third PCB electrode is spaced from a third spring electrode of the four spring electrodes by a second distance d2that is greater than d1, and a fourth PCB electrode of the four PCB electrodes is spaced from a fourth spring electrode of the four spring electrodes by approximately the second distance d2, the method comprising:
- determining a first change in capacitance ΔACH1 at the first PCB electrode of the four PCB electrodes in response to the force F and a second change in capacitance ΔCH2 at the second PCB electrode of the four PCB electrodes in response to the force F;
- using at least the first change in capacitance ΔCH1 and the second change in capacitance ΔCH2 to calculate a first local gradient G1 between the first PCB electrode and the second PCB electrode;
- using at least the first local gradient G1 to calculate a first local force F1 at the first PCB electrode and a second local force F2 at the second PCB electrode;
- determining a third change in capacitance ΔCH3 at the third PCB electrode of the four PCB electrodes in response to the force F and a fourth change in capacitance ΔCH4 at the fourth PCB electrode of the four PCB electrodes in response to the force F;
- using at least the third change in capacitance ΔCH3 and the fourth change in capacitance ΔCH4 to calculate a second local gradient G2 between the third PCB electrode and the fourth PCB electrode;
- using at least the second local gradient G2 to calculate a third local force F3 at the third PCB electrode and a fourth local force F4 at the fourth PCB electrode;
- and
- using at least the first local force F1, the second local force F2, the third local force F3, and the fourth local force F4 to calculate the force F exerted on the touchpad.
A computing device, comprising:
- a force sensing touchpad comprising:
- a printed circuit board (PCB) comprising four PCB electrodes;
- a base plate spaced from the PCB and defining an aperture;
- and
- a spring mounted on the base plate and overlying the aperture, the spring comprising four spring electrodes, wherein each of the four PCB electrodes is spaced from and overlies one of the four spring electrodes of the spring, wherein a first current distance between the PCB and the base plate at a first PCB electrode of the four PCB electrodes is d01, the first PCB electrode is spaced from a first spring electrode of the four spring electrodes by a first distance d1, a second PCB electrode of the four PCB electrodes is spaced from a second spring electrode of the four spring electrodes by approximately the first distance d1, a second current distance between the PCB and the base plate at a third PCB electrode of the four PCB electrodes is d02, the third PCB electrode is spaced from a third spring electrode of the four spring electrodes by a second distance d2 that is greater than d1, and a fourth PCB electrode of the four PCB electrodes is spaced from a fourth spring electrode of the four spring electrodes by approximately the second distance d2;
- a processor;
- and
- a memory storing instructions executable by the processor to:
- determine a first change in capacitance ΔCH1 at the first PCB electrode of the four PCB electrodes in response to the force F and a second change in capacitance ΔCH2 at the second PCB electrode of the four PCB electrodes in response to the force F;
- use at least the first change in capacitance ΔCH1 and the second change in capacitance ΔCH2 to calculate a first local gradient G1 between the first PCB electrode and the second PCB electrode;
- use at least the first local gradient G1 to calculate a first local force at the first PCB electrode and a second local force at the second PCB electrode;
- determine a third change in capacitance ΔCH3 at the third PCB electrode of the four PCB electrodes in response to the force F and a fourth change in capacitance ΔCH4 at the fourth PCB electrode of the four PCB electrodes in response to the force F;
- use at least the third change in capacitance ΔCH3 and the fourth change in capacitance ΔCH4 to calculate a second local gradient G2 between the third PCB electrode and the fourth PCB electrode;
- use at least the second local gradient G2 to calculate a third local force at the third PCB electrode and a fourth local force at the fourth PCB electrode;
- use at least the first local force, the second local force, the third local force, and the fourth local force to calculate a force F exerted on the touchpad.
The computing device of 12, wherein the first spring electrode and the second spring electrode each comprise centroids aligned on a first axis, and the third spring electrode and the fourth spring electrode each comprise centroids aligned on a second axis perpendicular to the first axis.
The computing device of 17, wherein the spring comprises:
- a first beam extending from a first internal wall to a second side of a central portion that overlies the aperture defined in the base plate;
- and
- a second beam extending from a second internal wall that is opposite to the first internal wall to a first side of the central portion that is opposite to the second side.
The computing device of 18, wherein the first spring electrode, second spring electrode, third spring electrode, and fourth spring electrode are integral portions of the spring.
A computing device, comprising:
- a force sensing touchpad comprising:
- a printed circuit board (PCB) comprising four PCB electrodes;
- a base plate spaced from the PCB and defining an aperture;
- and
- a spring mounted on the base plate and overlying the aperture, the spring comprising four spring electrodes, wherein each of the four PCB electrodes is spaced from and overlies one of the four spring electrodes of the spring;
- a processor;
- and
- a memory storing instructions executable by the processor to:
- determine a first change in capacitance ΔCH1 at a first PCB electrode of the four PCB electrodes in response to the force F and a second change in capacitance ΔCH2 at a second PCB electrode of the four PCB electrodes in response to the force F;
- use at least the first change in capacitance ΔCH1 and the second change in capacitance ΔCH2 to calculate a first local gradient G1 between the first PCB electrode and the second PCB electrode;
- use at least the first local gradient G1 to calculate a first local force at the first PCB electrode and a second local force at the second PCB electrode;
- determine a third change in capacitance ΔCH3 at a third PCB electrode of the four PCB electrodes in response to the force F and a fourth change in capacitance ΔCH4 at a fourth PCB electrode of the four PCB electrodes in response to the force F;
- use at least the third change in capacitance ΔCH3 and the fourth change in capacitance ΔCH4 to calculate a second local gradient G2 between the third PCB electrode and the fourth PCB electrode;
- use at least the second local gradient G2 to calculate a third local force at the third PCB electrode and a fourth local force at the fourth PCB electrode;
- use at least the first local force, the second local force, the third local force, and the fourth local force to calculate a force F exerted on the touchpad,
- wherein a first current distance between the PCB and the base plate at the first PCB electrode is d01, the first PCB electrode is spaced from a first spring electrode of the four spring electrodes by a first distance d1, the second PCB electrode is spaced from a second spring electrode of the four spring electrodes by approximately the first distance d1, a second current distance between the PCB and the base plate at the third PCB electrode is d02, the third PCB electrode is spaced from a third spring electrode of the four spring electrodes by a second distance d2 that is greater than d1, and the fourth PCB electrode is spaced from a fourth spring electrode of the four spring electrodes by approximately the second distance d2, and
- wherein the first spring electrode, second spring electrode, third spring electrode, and fourth spring electrode are integral portions of the spring.
Dependencies are inferred from the claim text.