Fingerprint-Assisted Force Estimation

• US 20160070404A1
• Filed: 06/18/2015
• Published: 03/10/2016
• Est. Priority Date: 07/26/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Kerr, Duncan, Hotelling, Steven P.
• Granted Patent: US 10,949,020 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• 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 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06V 40/13 Sensors therefor
• CPC Class Codes: G06V 40/1376 Matching features related to ridge properties or fingerprint texture
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/9627 Optical touch switches
• CPC Class Codes: H03K 17/9629 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/9643 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: H03K 2217/94036 Multiple detection, i.e. where different switching signals are generated after operation of the user is detected at different time instants at different locations during the actuation movement by two or more sensors of the same or different kinds
• CPC Class Codes: H03K 2217/96003 using acoustic waves, e.g. ultrasound

Abstract

Embodiments may take the form of a system having a user input device and a first sensor coupled to the user input device. The first sensor is configured to sense touch on a surface of the user input device. The system may also include a second sensor in communication with the surface of the user device configured to sense wetting of a user'"'"'s fingerprint on the surface. The system has a processor coupled to the first and second sensors and configured to estimate an amount of force applied by the user'"'"'s fingerprint based at least in part upon the sensed wetting of the user'"'"'s fingerprint.

Claims

1. A system comprising:

a user input device;

a first sensor coupled to the user input device, wherein the first sensor is configured to sense touch on a surface of the user input device;

a second sensor configured to sense a characteristic of a user'"'"'s fingerprint on the surface;

a processor coupled to the first and second sensors and configured to estimate an amount of force applied to the surface by the user'"'"'s finger based at least in part upon the sensed characteristic of the user'"'"'s fingerprint, said characteristic measured by an evaluation of ridges to valleys within a contact area in the user'"'"'s fingerprint.

2. The system of claim 1, wherein the second sensor comprises one of a capacitive touch sensor, a frustrated total internal reflection sensor, or an ultrasonic sensor.

3. The system of claim 1, wherein the first sensor comprises a capacitive touch sensor.

4. The system of claim 1, wherein the user input device comprises a touch screen display device.

5. The system of claim 4, wherein the touch screen display device comprises one of an organic light emitting diode device or a liquid crystal display device.

6. The system of claim 1, wherein the user input device comprises one of a trackpad, a mouse, or a touch screen.

7. The system of claim 1, further comprising a force calibration system.

8. The system of claim 7, wherein the force calibration system comprises:

a mechanical actuator; and

a touch sensor.

9. The system of claim 8, wherein the mechanical actuator comprises a button having a known force threshold.

10. The system of claim 9, wherein the known force threshold is approximately 200 grams.

11. The system of claim 8, wherein the touch sensor comprises one of a capacitive touch sensor, a frustrated total internal reflectance sensor or an ultrasonic sensor.

12. The system of claim 7, wherein the force calibration system is integrated into a home button of the device.

13. The system of claim 7 further comprising a look up table, the look up table correlating a calibration value obtained from the calibration system with values sensed by the second sensor to estimate an amount of force applied to the user input device.

14. A method of approximating force comprising:

storing a calibration value in a non-transitory storage medium;

determining a contact area of a finger on a fingerprint sensor;

determining a ratio of ridges to valleys in the contact area;

obtaining force data from a solid state force sensor; and

determining a force value based upon the force data, the contact area and the ratio.

15. The method of claim 14 further comprising:

operating a mechanical actuator, the mechanical actuator having a known force threshold; and

capturing the calibration value by reading data from a touch sensor associated with the mechanical actuator.

16. The method of claim 14, wherein obtaining force data comprises operating at least one of:

a capacitive touch sensor;

a frustrated total internal reflectance sensor;

or

an ultrasonic sensor.

17. The method of claim 14, wherein determining a force value comprises referencing a look-up table.

18. The method of claim 14, wherein determining a force value comprises computing a force value by scaling the force data based on the calibration value.

19. The method of claim 14 further comprising replacing the stored calibration data upon initiation of each unique session.

20. The method of claim 15, wherein the known force threshold is approximately 200 grams.