Engineering displacement response through electrode shape

• US 10,642,428 B2
• Filed: 06/25/2018
• Issued: 05/05/2020
• Est. Priority Date: 06/25/2018
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Bulea, Mihai, Schmitt, Felix
• Primary Examiner(s): Polo, Gustavo
• Application Number:
  US16/017,414
• Publication Number:
  US 20190391684A1
• Time in Patent Office: 680 Days
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A method includes obtaining a capacitive function of ground plane displacement and gap distance, and optimizing, using the capacitive function, an optimization function to obtain multiple slice lengths. The slice lengths correspond to multiple gap distances between a first sensor electrode and a second sensor electrode. The method further includes defining a sensor electrode shape using slice lengths and gap distances, defining a sensor electrode pattern based on the sensor electrode shape, and storing the sensor electrode pattern.

Claims

1. A method comprising:

obtaining a capacitive function of ground plane displacement and gap distance;

optimizing, using the capacitive function, an optimization function to obtain a plurality of slice lengths, the plurality of slice lengths corresponding to a plurality of gap distances between a first sensor electrode and a second sensor electrode, wherein the optimizing comprises;

selecting a displacement response function for the sensor electrode pattern to obtain a selected displacement response function;

defining an objective function based on the selected displacement response function; and

performing an optimization of the objective function;

defining a sensor electrode shape using the plurality of slice lengths and the plurality of gap distances;

defining a sensor electrode pattern based on the sensor electrode shape; and

storing the sensor electrode pattern.

2. The method of claim 1, further comprising:

obtaining a size of a sensor parameter; and

configuring a sensor length constraint using the size of the sensor parameter, wherein performing the optimization is to satisfy the sensor length constraint.

3. The method of claim 2, further comprising:

configuring the sensor length constraint using a sensor length regularization constant.

4. The method of claim 1, further comprising:

obtaining a sensor to ground distance range,

wherein the capacitive function uses the sensor to ground distance range.

5. The method of claim 1, further comprising:

configuring a smoothness constraint using a smoothness regularization constant, wherein performing the optimization is to satisfy the smoothness constraint.

6. The method of claim 1, further comprising:

obtaining a response signal parameter; and

configuring a response signal constraint using the response signal parameter, wherein performing the optimization is to satisfy the response signal constraint.

7. The method of claim 6, further comprising:

configuring the response signal constraint using a response signal regularization constant.

8. The method of claim 1, further comprising:

fabricating force sensor according to the sensor electrode pattern.

9. A system for engineering a displacement response comprising:

a data repository for storing a capacitive function of ground plane displacement and gap distance; and

a computer processor operatively connected to the data repository, the computer processor configured to;

obtain a capacitive function of ground plane displacement and gap distance,

optimize, using the capacitive function, an optimization function to obtain a plurality of slice lengths, the plurality of slice lengths corresponding to a plurality of gap distances between a first sensor electrode and a second sensor electrode, wherein the optimizing comprises;

selecting a displacement response function for the sensor electrode pattern to obtain a selected displacement response function,

defining an objective function based on the selected displacement response function, and

performing an optimization of the objective function,

define a sensor electrode shape using the plurality of slice lengths and the plurality of gap distances,

define a sensor electrode pattern based on the sensor electrode shape, and

store the sensor electrode pattern.

10. The system of claim 9, wherein the computer processor is further configured to:

obtain a size of a sensor parameter; and

configure a sensor length constraint using the size of the sensor parameter, wherein performing the optimization is to satisfy the sensor length constraint.

11. The system of claim 10, wherein the computer processor is further configured to:

configure the sensor length constraint using a sensor length regularization constant.

12. The system of claim 9, wherein the computer processor is further configured to:

obtain a sensor to ground distance range,

wherein the capacitive function uses the sensor to ground distance range.

13. The system of claim 9, wherein the computer processor is further configured to:

configure a smoothness constraint using a smoothness regularization constant, wherein performing the optimization is to satisfy the smoothness constraint.

14. The system of claim 9, wherein the computer processor is further configured to:

obtain a response signal parameter; and

configure a response signal constraint using the response signal parameter, wherein performing the optimization is to satisfy the response signal constraint.

15. The system of claim 14, wherein the computer processor is further configured to:

configure the response signal constraint using a response signal regularization constant.

16. A capacitive input device comprising:

a transmitter sensor electrode;

a receiver sensor electrode, the receiver sensor electrode parallel in a first direction to the transmitter sensor electrode,

wherein the receiver sensor electrode and the transmitter sensor electrode are on a single layer,

a ground plane; and

a compressible layer interposed between the ground plane and the single layer,

wherein a gap distance between the transmitter sensor electrode and the receiver sensor electrode monotonically increases along the first direction of the transmitter sensor electrode and the receiver sensor electrode.

17. The capacitive input device of claim 16, wherein compression of the compressible layer causes a substantially linear capacitive response detected using the receiver electrode.