HYBRID FORCE SENSITIVE TOUCH DEVICES

• US 20130342501A1
• Filed: 06/11/2013
• Published: 12/26/2013
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Anders L. Molne
• Inventors: Griffith, David, Mlne, Anders L.
• Granted Patent: US 9,329,719 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 an (x,y) plane as well as a force of said touch F_z along a z-axis, comprising:

an open-face housing;

an open frame covering said open-face housing;

a touch display screen captive in said housing and exposed through said open frame, said touch display screen adapted to calculate coordinates of a touch in an (x,y) plane using any one from among the group of projective capacitive, surface capacitive, resistive, digital resistive, SAW, IR, APR, DST, optical and electromagnetic sensing media;

a support structure underlying said touch display screen;

at least one force-based force sensor underlying said support structure for determining a force of said touch perpendicular to said (x,y) plane; and

a control system, said control system including non-transitory computer memory, and a programmable controller programmed with control software comprising computer instructions stored on said non-transitory computer memory for determining the coordinates of a touch in an (x,y) plane from said touch display screen, for determining a force F_c of said touch perpendicular to said (x,y) plane from said force-based force sensor, and for reconciling said coordinates (x,y) with said F_c force and interpreting the reconciled result.

2. The touch-sensitive display assembly according to claim 1, wherein said at least one force-based force sensor comprises four corner-mounted force-based sensors.

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

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

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

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

7. The touch-sensitive display assembly according to claim 6, wherein said continuous rectangular gasket comprises Poron™

.

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

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

10. The touch-sensitive display assembly according to claim 1, wherein said at least one force-based force sensor comprises a force sensing resistive (FSR) sensor.

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

12. The touch-sensitive display assembly according to claim 1, wherein said at least one force-based force sensor comprises a force transducing rubber (FTR) sensor.

13. The touch-sensitive display assembly according to claim 1, wherein said control software for determining a force F_c of said touch subdivides an area of said touch display screen into a plurality of predefined concentric areas, and computes an absolute touch pressure Fz at the calculated coordinates in said (x,y) plane by compensating said measured force F_c as a function of the predefined concentric area within which said touch occurred.

14. The touch-sensitive display assembly according to claim 13, wherein said control software ignores a touch if said absolute touch pressure Fz is below a predetermined minimum threshold.

15. The touch-sensitive display assembly according to claim 1, wherein said control system further comprises,

a first programmable controller programmed with control software comprising computer instructions stored on said non-transitory computer memory for determining the coordinates of a touch in an (x,y) plane from said touch display screen,

a second programmable controller programmed with control software comprising computer instructions stored on said non-transitory computer memory for determining a force F_c of said touch perpendicular to said (x,y) plane from said force-based force sensor, and

a third programmable controller programmed with control software comprising computer instructions stored on said non-transitory computer memory for reconciling said coordinates (x,y) with said F_c force and interpreting the reconciled result.

16. The touch-sensitive display assembly according to claim 1, wherein the control software computes a first set of touch coordinates (x,y) from said force sensing sensors, and a second set of coordinates (x,y,Fz) from said touch sensitive display screen.

17. A hybrid touch-screen display, comprising:

a touch panel comprising any one from among the group consisting of projective capacitive, surface capacitive, resistive, digital resistive, SAW, IR, APR, DST, optical and electromagnetic touch-screens; and

at least one force-based touch sensor coupled to said touch panel;

whereby said touch panel outputs (x,y) coordinates to a processor, and said at least one force-based touch sensor outputs a z-force coordinate to a processor;

software for reconciling said touch panel outputs (x,y) coordinates with said z-force coordinate and for interpreting said reconciled data.

18. A touch-sensitive device, comprising:

one or more force sensors for relative force measurement in a system in which force is traditionally not measured; and

software for compensating said relative force measurement to calibrate for varying static loads and to filter extraneous loads.