Hybrid force sensitive touch devices

• US 9,329,719 B2
• Filed: 06/11/2013
• Issued: 05/03/2016
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Mlne, Anders L., Griffith, David
• Primary Examiner(s): Ghebretinsae, Temesgh
• Assistant Examiner(s): Jansen, II, Michael J
• Application Number:
  US13/915,267
• Publication Number:
  US 20130342501A1
• Time in Patent Office: 1,057 Days
• Field of Search: 345/173, 345/174
• US Class Current: 1/1
• 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 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/04142 the force sensing means being located peripherally, e.g. disposed at the corners or at the side of a touch sensing plate
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

Abstract

A hybrid touch-screen display that integrates force-based touch-screen technology with any one from among a group of projective capacitive, surface capacitive, resistive, digital resistive, SAW, IR, APR, DST, optical and electromagnetic touch-screen technologies to provide an ability to compensate for non-perfect force transfer. An alternate implementation is also disclosed that employs a single force sensor for relative force measurement in a system in which force is traditionally not measured, here a water dispenser unit. This allows compensation for varying static loads, run-time calibration, and filtering of extraneous loads through firmware.

Claims

1. A touch-sensitive display assembly adapted to calculate coordinates of a touch in a coordinate plane as well as a force of the touch along a z-axis, the touch-sensitive display assembly comprising:

a housing;

a frame coupled to the housing;

a touch display screen in the housing and exposed through the frame, the touch display screen adapted to calculate coordinates of the touch in a coordinate plane using one or more sensors;

a support structure underlying the touch display screen;

at least one force sensor underlying the support structure, the at least one force sensor adapted to determine a force of the touch perpendicular to the coordinate plane; and

a control system comprising a non-transitory computer memory for storing instructions for;

determining the coordinates of the touch in the coordinate plane from the touch display screen;

determining a force component of the touch perpendicular to the coordinate plane from the force sensor;

subdividing an area of the touch display screen into a plurality of concentric areas; and

computing an absolute touch pressure at the determined coordinates in the coordinate plane by compensating the force component as a function of the predefined concentric area within which the touch occurred.

2. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor is a corner-mounted force-based sensor.

3. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor is surface-mounted on the back of the support structure.

4. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor is mounted on a printed circuit board inside the housing.

5. The touch-sensitive display assembly according to claim 1, further comprising rubberized padding between the housing and touch sensitive display screen.

6. The touch-sensitive display assembly according to claim 5, wherein the rubberized padding comprises a continuous rectangular gasket.

7. The touch-sensitive display assembly according to claim 6, wherein the continuous rectangular gasket comprises silicon.

8. The touch-sensitive display assembly according to claim 6, wherein the rubberized padding imposes a predetermined preload force to the touch sensitive display screen to minimize impact from shock and vibration.

9. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor comprises a force sensing resistive sensor.

10. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor comprises a piezo resistive sensor.

11. The touch-sensitive display assembly according to claim 1, wherein the at least one force sensor comprises a force transducing rubber sensor.

12. The touch-sensitive display assembly according to claim 1, wherein the control software ignores a touch if the absolute touch pressure is below a predetermined minimum threshold.

13. The touch-sensitive display assembly according to claim 1, wherein the control software computes a first set of touch coordinates from the force sensing sensors, and a second set of coordinates from the touch sensitive display screen.