SNAP DOMES AS SENSOR PROTECTION

• US 20120200526A1
• Filed: 02/09/2012
• Published: 08/09/2012
• Est. Priority Date: 02/09/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Lackey, Mark
• Granted Patent: US 9,389,721 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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: H01H 2215/006 Only mechanical function
• CPC Class Codes: H01H 2215/036 Metallic disc
• CPC Class Codes: H01H 2221/03 Stoppers for on or off position
• CPC Class Codes: H01H 2221/064 Limitation of actuating pressure

Abstract

A protection mechanism for force-based touch sensitive input panels or displays comprising a “snap dome”, e.g., a semi-rigid pliable dome positioned over each sensor for increased overload protection. The snap dome is unidirectionally-resilient to a known point of collapse. It therefore imparts a predetermined resistance to compression over a known range of travel along the z-axis, but is unyielding along the x- and y-axis. As the touch panel is depressed toward the standoff, the snap dome resists compression until it collapses, allowing the touch panel to encounter the standoff. The standoff then imparts dead-stop overload force protection to the sensors. This allows for the placement of mechanical stops (such as stop screws) with a less exacting tolerance. Moreover, the snap domes introduce no x- or y-axis force losses/increases, and do not cause tilting of the touch panel. The touch force remains perfectly perpendicular and accuracy is preserved.

Claims

8. A protection mechanism for force-based touch sensitive inputs, comprising:

a snap dome interposed between a force-based sensor and an opposing surface, said snap dome being formed from a semi-rigid pliable material shaped in a generally concave shape with a bearing surface for abutting the sensor and a symmetric supporting foundation about the bearing surface, said snap dome being unidirectionally-resilient to a known point of collapse.

9. The protection mechanism according to claim 8, wherein said snap dome comprises a semi-rigid concave annulus defined with a plurality of legs.

10. The protection mechanism according to claim 9, wherein said plurality of legs comprises four equi-angularly-spaced legs.

11. The protection mechanism according to claim 10, further comprising a standoff for imparting dead-stop overload force protection to the sensor when said snap dome collapses.

12. The protection mechanism according to claim 11, wherein said standoff is a rigid member having an axis parallel to a central axis of said snap-disk.

13. A device for overload protection of a force sensor, comprising:

a resilient snap dome sandwiched between said sensor and an opposing surface, said snap dome being formed from a semi-rigid pliable material in a generally concave shape with an apex abutting the sensor and a symmetric supporting foundation abutting the opposing surface, said snap dome being unidirectionally-resilient to a known point of collapse.

14. The device for overload protection of a force sensor according to claim 13, further comprising a standoff in proximity to said snap dome for imparting dead-stop overload force protection to the sensor when said snap dome collapses.

15. The device for overload protection of a force sensor according to claim 14, incorporated in a touch screen assembly for an electronic device having a processor, an electronic display screen, a substrate, a plurality of differentially-mounted force sensors mounted between said display screen and said substrate and electrically connected to the processor for registering a force z from a touch of said lens at any position.

16. A touch screen assembly for an electronic device having a processor, said touch screen assembly comprising;

an electronic LCD display screen;

a base substrate parallel to said display screen;

a circuit board between said LCD display screen and base substrate, said circuit board containing a number n of force sensors positioned along an x- and y-axis, said force sensor(s) being electrically connected to the processor for registering a force z from a touch of said circuit board at any position along said x- and y-axis and for providing an analog force signal z;

a number n of semi-rigid snap-dome(s) each mounted at a corner of said circuit board and facing said base substrate.

1. A touch screen assembly for an electronic device having a processor, said touch screen assembly comprising;

an electronic display screen;

a substrate;

a number n of differentially-mounted force sensors mounted between said display screen and said substrate and differentially positioned along an x- and y-axis, said force sensors being electrically connected to the processor for registering a force z from a touch of said lens at any position along said x- and y-axis and for providing an analog differential force signal z; and

a plurality n of differentially-mounted semi-rigid snap-domes each in a direct or indirect bearing relation with a corresponding one of said force sensors.

2. The touch screen assembly for an electronic device according to claim 1, wherein said number n is one (1).

3. The touch screen assembly for an electronic device according to claim 1, wherein said number n is two (2). The touch screen assembly for an electronic device according to claim 1, wherein said number n is four (4).

5. The touch screen assembly for an electronic device according to claim 1, wherein said snap-domes are unidirectionally-resilient along a z-axis in an x, y, z coordinate system, and impart a predetermined resistance to compression over a known range of travel along the z-axis, but are unyielding along the x- and y-axis.

6. The touch screen assembly for an electronic device according to claim 5, further comprising a standoff interposed between the display module and substrate for prevention of over-compression of said corresponding force sensor.

7. The touch screen assembly for an electronic device according to claim 6, wherein said stand-off is a stop screw.

18. The touch screen assembly for an electronic device according to claim 16, wherein said number n is four (4).

19. The touch screen assembly for an electronic device according to claim 18, wherein said snap-domes are unidirectionally-resilient along a z-axis in an x, y, z coordinate system, and impart a predetermined resistance to compression over a known range of travel along the z-axis, but are unyielding along the x- and y-axis.

20. The touch screen assembly for an electronic device according to claim 18, further comprising four corner-mounted standoffs interposed between the display module and the base substrate for prevention of over-compression of said corresponding force sensors.

21. The touch screen assembly for an electronic device according to claim 20, wherein said four corner-mounted standoffs are attached to said base substrate.

22. The touch screen assembly for an electronic device according to claim 21, wherein said four corner-mounted standoffs are posts integrally molded to said base substrate.

17. The touch screen assembly for an electronic device according to claim 17, wherein said number n is one (1).

19-1. The touch screen assembly for an electronic device according to claim 18, further comprising at least one standoff interposed between the display module and the base substrate for prevention of over-compression of said corresponding force sensor(s).