Scrolling input arrangements using capacitive sensors on a flexible membrane

• US 20070052044A1
• Filed: 02/14/2006
• Published: 03/08/2007
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moolsintong, Jan, Lynch, Brian, Hotelling, Steve, Lyon, Benjamin, Forsblad, Larry, Zadesky, Steve, Weber, Doug
• Granted Patent: US 7,671,837 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

Scrolling input arrangements are presented including: a flexible membrane; a number of capacitive sensors mechanically integrated with the flexible membrane, the capacitive sensors radially disposed with respect to a first axis that is perpendicular with respect to the flexible membrane; an integrated circuit mechanically coupled with the flexible membrane and electronically coupled with the capacitive sensors, the integrated circuit configured to process a number of electronic signals from the capacitive sensors to provide a scrolling function; and a connection region on the flexible membrane for electronically coupling the scrolling input arrangement with an electronic device. In some embodiments, the capacitive sensors are configured with a plate element having a first surface area and a trace element having a second surface area such that the first surface area and second surface area comprise a sensor surface area, wherein the sensor surface areas for the capacitive sensors is substantially equal in size.

Claims

1. A scrolling input arrangement comprising:

a flexible membrane;

a plurality of capacitive sensors mechanically integrated with the flexible membrane, the plurality of capacitive sensors radially disposed with respect to a first axis that is perpendicular with respect to the flexible membrane;

an integrated circuit mechanically coupled with the flexible membrane and electronically coupled with the plurality of capacitive sensors, the integrated circuit configured to process a plurality of electronic signals from the plurality of capacitive sensors to provide a scrolling function; and

a connection region on the flexible membrane for electronically coupling the scrolling input arrangement with an electronic device.

2. The arrangement of claim 1 wherein each of the plurality of capacitive sensors is configured with a plate element having a first surface area and a trace element having a second surface area such that the first surface area and second surface area comprise a sensor surface area, wherein the sensor surface areas for the plurality of capacitive sensors is substantially equal in size.

3. The arrangement of claim 1 wherein the integrated circuit includes logic for calibrating the plurality of capacitive sensors in response to a changing positive temperature gradient.

4. The arrangement of claim 3 wherein the changing positive temperature gradient is approximately 4°

C./ms within a range of approximately 0°

C. to 60°

C.

5. The arrangement of claim 2 further comprising:

a plurality of switches mechanically integrated with the flexible membrane, the plurality of switches configured for providing a plurality of selection functions wherein at least one of the plurality of switches is approximately co-located with the first axis.

6. The arrangement of claim 1 wherein the flexible membrane is a polyimide film.

7. The arrangement of claim 6 wherein the flexible membrane has a thickness of approximately 0.21 millimeters.

8. The arrangement of claim 6 wherein the flexible membrane is further configured with a plurality of anti-rotation elements for securing the flexible membrane against a rotational force.

9. The arrangement of claim 1 wherein the plurality of capacitive sensors includes at least 16 sensors.

10. A low-profile scrolling input assembly comprising:

a scrolling input arrangement for providing a scrolling function, the scrolling input arrangement having a top surface and a bottom surface, the scrolling input arrangement comprising,

a flexible membrane;

a plurality of capacitive sensors mechanically integrated with the flexible membrane, the plurality of capacitive sensors radially disposed with respect to a first axis that is perpendicular with respect to the flexible membrane;

an integrated circuit mechanically coupled with the flexible membrane, the integrated circuit electronically coupled with the plurality of capacitive sensors, the integrated circuit configured to process a plurality of electronic signals from the plurality of capacitive sensors to provide a scrolling function;

a connection region on the flexible membrane for electronically coupling the integrated circuit with a device;

a backing plate for providing mechanical support for the scrolling input arrangement, the backing plate mechanically coupled with the bottom surface; and

a cover plate for providing protecting the top surface, the cover plate configured to provide a low-friction surface to receive a user input.

11. The assembly of claim 10 further comprising:

a plurality of switches mechanically integrated with the flexible membrane, the plurality of switches configured for providing a plurality of selection functions.

12. The assembly of claim 11 wherein at least one of the plurality of switches is approximately co-located with the first axis.

13. The assembly of claim 11 wherein the backing plate further comprises a plurality of actuator nubs for actuating the plurality of switches.

14. The assembly of claim 10 wherein the cover plate further comprises a plurality of actuator nubs for actuating a plurality of switches mechanically integrated with the flexible membrane.

15. The assembly of claim 10 wherein the integrated circuit includes logic for calibrating the plurality of capacitive sensors in response to a changing positive temperature gradient.

16. The assembly of claim 15 wherein the changing positive temperature gradient is approximately 4°

C./ms within a range of approximately 0°

C. to 60°

C.

17. The assembly of claim 10 further comprising a plurality of anti-rotation elements for securing the assembly against a rotational force.

18. A method of calibrating a plurality of capacitive sensors in response to a changing positive temperature gradient, comprising:

establishing a baseline, the baseline comprising a first minimum function of a signal from each of the plurality of capacitive sensors;

scanning the plurality capacitive sensors; and

if more than eight of the plurality of capacitive sensors exceeds a threshold value,

determining a thermal drift of the plurality of capacitive sensors, the thermal drift corresponding to a second minimum function of a signal from each of the plurality of capacitive sensors, and

for each of the plurality of capacitive sensors, calculating an updated baseline based on the baseline and the thermal drift such that the plurality of capacitive sensors is calibrated.

19. The method of claim 18 wherein the threshold value is selected to avoid a noise floor of the plurality of capacitive sensors.

20. The method of claim 18 wherein the scanning the plurality of capacitive sensors frequency is conducted at a frequency of approximately three megahertz.