Touchpad with capacitive force sensing

Patent metadata

Field	Value
Publication number	US-9349552-B2
Application number	US-201213606005-A
Country	US
Kind code	B2
Filing date	Sep 6, 2012
Priority date	May 24, 2010
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

Described herein are techniques related to a touchpad with capacitive force sensing. The described techniques may determine the point or region of a user-engagement surface contacted by a user. In addition, the described techniques may also determine a force of the user's finger press on the user-engagement surface using one or more capacitance force-sensors. Furthermore, the described techniques may offer active tactile feedback (i.e., haptics) to the user's finger touching the user-engagement surface. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

First claim

What is claimed is:

1. An input device comprising:
a touchsurface;
a sensor board coupled to the touchsurface, the sensor board including a capacitive touch sensor configured to detect positions of one or more input objects proximate to the touchsurface, the sensor board further including one or more capacitive force-sensing strips disposed proximate an edge of the sensor board;
a planar spring plate including a perimeter region surrounding a planar interior region, the planar interior region configured to be mechanically coupled to the sensor board and the perimeter region including a return mechanism configured to be coupled to a housing; and
a mounting device mechanically coupled to the planar interior region and the sensor board, wherein the mounting device forms a defined gap between the planar interior region and the sensor board,
wherein the mounting device is configured to maintain the defined gap at a fixed distance between the planar interior region and the sensor board,
wherein the planar interior region of the planar spring plate is configured to move downwardly relative to the perimeter region and to the housing in response to a force applied to the touchsurface by the one or more input objects, and further wherein the perimeter region remains fixed relative to the housing in response to the force applied to the touchsurface by the one or more input objects,
wherein the one or more capacitive force-sensing strips and the perimeter region of the planar spring plate define a capacitive-sensing gap for a capacitive force sensor, such that the force applied to the touchsurface deflects the planar interior region of the planar spring plate relative to the return mechanism and changes a capacitance in the capacitive-sensing gap, and
wherein the planar interior region of the planar spring plate returns to a planar position with the perimeter region of the planar spring plate upon removal of the applied force.

2. An input device as recited in claim 1 , wherein the planar spring plate comprises a conductive plane of sheet metal in the absence of applied force.

3. An input device as recited in claim 1 , wherein the return mechanism comprises a plurality of leaf springs.

4. An input device as recited in claim 1 , wherein the planar spring plate is configured to allow deflection of the planar interior region relative to the housing in response to a force imparted on the touchsurface, and further wherein the capacitive force sensor is sensitive to force and does not capacitively couple with the one or more input objects.

5. An input device as recited in claim 1 , wherein the return mechanism comprises a plurality of leaf springs and the sensor board comprises a plurality of capacitive-sensing strips such that the spring plate forms a plurality of force-sensing capacitors, each force-sensing capacitor comprising a pair of capacitive-sensing strips and a leaf spring.

6. An input device as recited in claim 1 , wherein the sensor board comprises a printed circuit board and the capacitive touch sensor comprises a capacitive-sensing pattern disposed on the sensor board.

7. An input device as recited in claim 1 , further comprising a sensor module, wherein the sensor module is configured to determine a position of the one or more input objects proximate to the touchsurface and a force imparted on the touchsurface by the one or more input objects.

8. An input device as recited in claim 7 , wherein the sensor module is configured to determine the position of the one or more input objects using the capacitive touch sensor and is further configured to determine the force imparted on the touchsurface by the one or more input objects using at least the capacitive force sensor, and further wherein the capacitive force sensor is sensitive to force and does not capacitively couple with the one or more input objects.

9. An input device as recited in claim 1 , wherein the one or more input objects comprise at least one of a human finger, a human body part, a pen, a pencil, and a stylus.

10. A method of facilitating an operation of a touchpad, the touchpad comprising:
a touchsurface coupled to a sensor board, wherein the sensor board includes a capacitive touch sensor configured to detect positions of one or more input objects proximate to the touchsurface and one or more capacitive force-sensing strips disposed proximate an edge of the sensor board;
a planar conductive substrate including a perimeter region having a return mechanism, the perimeter region surrounding a planar interior region; and
a mounting device mechanically coupled to the planar interior region and the sensor board, wherein the mounting device forms a defined gap between the planar interior region and the sensor board, wherein the mounting device is configured to maintain the defined gap at a fixed distance between the planar interior region and the sensor board,
wherein the one or more capacitive force-sensing strips and the perimeter region of the planar spring plate define a capacitive-sensing gap for a capacitive force sensor,
wherein the planar interior region is configured to move downwardly relative to the perimeter region and to a housing in response to a force applied to the touchsurface by the one or more input objects, the method comprising:
determining, based upon one or more signals from the capacitive touch sensor, positional information of the one or more input objects proximate to the touchsurface;
determining a force imparted by the one or more input objects onto the touchsurface based on a measurement of a change in capacitance in the capacitive-sensing gap using one or more signals from the capacitive force sensor; and
performing a user-interface feedback action based on one or more of the positional information or a force imparted on the touchsurface.

11. A method as recited in claim 10 , wherein determining the force includes determining a variable capacitance of the capacitive force sensor from a deflection of the one or more capacitive-sensing strips relative to the planar conductive substrate, and further wherein the capacitive force sensor is sensitive to force and does not capacitively couple with the one or more input objects.

12. A method as recited in claim 10 , wherein determining the force includes determining a variable capacitance of the capacitive force sensor from a deflection of the one or more capacitive-sensing strips relative to the conductive substrate, the capacitive force sensor including the one or more capacitive-sensing strips and the return mechanism of the conductive substrate.

13. A method as recited in claim 10 , wherein the conductive substrate is configured to respond to a force applied to the touchsurface by deflection of the interior space relative the housing, and further wherein the planar conductive substrate returns to a planar position upon removal of the applied force.

14. A method as recited in claim 10 , wherein:
the return mechanism includes a plurality of leaf springs and the sensor board includes a plurality of capacitive-sensing strips such that the planar spring plate forms a plurality of capacitive force sensors, each capacitive force sensor including a pair of capacitive-sensing strips and a leaf spring; and
determining the force is based upon one or more signals from the plurality of capacitive force sensors.

15. A method as recited in claim 10 , wherein the user-interface feedback action is selected from a group consisting of accessing a file, menu pull down, menu selection, icon or button selection, program execution, properties access, cursor positioning, character or image selection, si

Assignees

• Huska Andrew P
• Krumpelman Douglas M
• Peterson Cody G
• Synaptics Inc

Inventors

• Huska Andrew P
• Krumpelman Douglas M
• Peterson Cody G

Classifications

• H01H2003/008

  with a haptic or a tactile feedback controlled by electrical means, e.g. a motor or magnetofriction · CPC title

• H01H2215/05

  electromechanical · CPC title

• G06F3/016

  Input arrangements with force or tactile feedback as computer generated output to the user · CPC title

• H01H13/85 Primary

  characterised by tactile feedback features · CPC title

• G06F3/0414

  using force sensing means to determine a position · CPC title