Motion Based Capacitive Sensor System

• US 20160306455A1
• Filed: 04/14/2015
• Published: 10/20/2016
• Est. Priority Date: 04/14/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: BUTTOLO, Pietro, LOBO, Harry, RANKIN, James Stewart II, RITTER, Kassandra, GHOSH, Dipanjan, SALTER, Stuart C., SMITH, Jessica
• Granted Patent: US 10,409,426 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60R 25/23 using manual input of alphanumerical codes
• CPC Class Codes: E05B 81/77 comprising sensors detecting the presence of the hand of a user
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes
• 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

Abstract

A proximity sensing system may include a conductive first trace and a conductive second trace adjacent to, interleaved with, and electrically isolated from the first trace. A density of the traces varies along a first axis such that rates of change of capacitance between the traces associated with movement, through an electric field, of an object in a direction of the first axis at a constant velocity are indicative of the direction. The sensing system may further include a conductive third trace adjacent to, interleaved with, and electrically isolated from the first trace. A first area between the first trace and second trace is independent of and isolated from a second area between the first trace and the third trace. Also, a density of the first and third traces may vary along the first axis.

Claims

1. A proximity sensing system comprising:

a conductive first trace; and

a conductive second trace adjacent to, interleaved with, and electrically isolated from the first trace, wherein a density of the traces varies along a first axis such that rates of change of capacitance between the traces associated with movement, through an electric field, of an object in a direction of the first axis at a constant velocity are indicative of the direction.

2. The sensing system of claim 1 further including:

a conductive third trace adjacent to, interleaved with, and electrically isolated from the first trace, wherein a density of the first and third traces varies along the first axis such that rates of change of capacitance between the first and third traces associated with movement, through an electric field, of an object in a direction of the first axis at a constant velocity are indicative of the direction, wherein a first area between the first trace and second trace is independent of and isolated from a second area between the first trace and the third trace.

3. The sensing system of claim 2 further comprising:

a display; and

a controller programmed to

increment a modulo counter in response to a first signal based on a first change in capacitance between the first and second traces indicative of an object in proximity to the first area,

output a value of the counter on the display,

enter the value of the counter in a memory in response to a second signal based on a second change in capacitance between the first and third traces indicative of an object in proximity to the second area to generate an access code, and

unlock a door lock system based on the access code matching a key code.

4. The sensing system of claim 2 further comprising:

a controller programmed to

generate an access code in response to a sequence of swipes, each swipe based on a second signal being a change in capacitance between the first and third traces indicative of a speed and a direction of an object in proximity to the second area, and

unlock a door lock based on the access code matching a key code.

5. The sensing system of claim 1, wherein the density of the traces generally increases providing a gradient along a second axis generally perpendicular to the first axis such that rates of change of capacitance between the first and second traces associated with movement of an object through an electric field at a constant velocity in a direction of the second axis are indicative of the direction of the second axis.

6. The sensing system of claim 5, wherein the density of the traces varies along the second axis such that a capacitance profile resulting from movement of an object across an area of the traces through an electric field over the second axis includes more than one stationary point in the rates of change in capacitance.

7. The sensing system of claim 1, wherein the first and second traces define a pattern that is asymmetrical about a second axis that is generally perpendicular to the first axis.

8. The sensing system of claim 7, wherein the pattern is trapezoidal, square or circular.

9. A controller-implemented method comprising:

outputting by the controller a first signal based on rates of change of capacitance between a first and second trace of a capacitive sensor pad having a first trace density gradient along a first axis within a first area such that the first signal is indicative of a direction of movement of an object through an electric field associated with the capacitive sensor pad at a constant velocity along the first axis.

10. The method of claim 9, further comprising outputting by the controller a second signal based on rates of change of capacitance between the first trace and a third trace of the capacitive sensor pad having a second trace density gradient along the first axis within a second area such that the second signal is indicative of a direction of movement of an object through the electric field at a constant velocity along the first axis, wherein the first area is independent of and isolated from the second area.

11. The method of claim 10 further comprising

incrementing a modulo counter in response to the first signal;

outputting a value of the counter on a display;

entering the value of the counter in a memory in response to the second signal to generate an access code; and

unlocking a door lock system based on the access code matching a key code.

12. The method of claim 10 further comprising:

outputting an access code based on a sequence of swipes, each swipe including a press, movement, and release of an object in proximity to the second area; and

unlocking a door lock based on the access code matching a key code.

13. The method of claim 9, wherein the first signal has a first signal profile with a single stationary point in the rates of change in capacitance associated with movement of an object through an electric field at a constant velocity in a direction of the first axis and has a second signal profile with at least three stationary points in the rates of change in capacitance associated with movement of an object through an electric field at a constant velocity in a direction of a second axis generally perpendicular to the first axis due to a region of reduced trace density offset from a median of the second axis.

14. A proximity sensing system comprising:

first and second traces electrically isolated from each other and defining a pattern having a trace density that varies along an axis perpendicular to an axis of asymmetry of the pattern such that rates of change of capacitance between the first and second traces associated with movement through an electric field of an object at a constant velocity in a direction perpendicular to the axis are indicative of the direction.

15. The sensing system of claim 14 further including:

a third trace adjacent to, interleaved with, and electrically isolated from the first trace, wherein a density of the first and third traces varies along a first axis such that rates of change of capacitance between the first and third traces associated with movement, through an electric field, of an object in a direction of the first axis at a constant velocity are indicative of the direction, wherein a first area between the first trace and second trace is independent of and isolated from a second area between the first trace and the third trace.

16. The sensing system of claim 15 further comprising:

a display; and

a controller programmed to

increment a modulo counter in response to a first signal based on a first change in capacitance between the first and second traces indicative of an object in proximity to the first area,

output a value of the counter on the display,

enter the value of the counter in a memory in response to a second signal based on a second change in capacitance between the first and third traces indicative of an object in proximity to the second area to generate an access code, and

unlock a door lock system based on the access code matching a key code.

17. The sensing system of claim 15 further comprising:

a controller programmed to

generate an access code in response to a sequence of swipes, each swipe based on a second signal being a change in capacitance between the first and third traces indicative of a speed and a direction of an object in proximity to the second area, and

unlock a door lock based on the access code matching a key code.

18. The sensing system of claim 15, wherein the trace density generally increases providing a gradient along a second axis generally perpendicular to the first axis such that rates of change of capacitance between the first and second traces associated with movement of an object through an electric field at a constant velocity in a direction of the second axis are indicative of the direction of the second axis.

19. The sensing system of claim 18, wherein the density of the traces varies along the second axis such that a capacitance profile resulting from movement of an object across an area of the traces through an electric field over the second axis includes more than one stationary point in the rates of change in capacitance.