Touch pad with force sensors and actuator feedback
Electronic devices may use touch pads that have touch sensor arrays, force sensors, and actuators for providing tactile feedback. A touch pad may be mounted in a computer housing. The touch pad may have a rectangular planar touch pad member that has a glass layer covered with ink and contains a capacitive touch sensor array. Force sensors may be mounted under each of the four corners of the rectangular planar touch pad member. The force sensors may be used to measure how much force is applied to the surface of the planar touch pad member by a user. Processed force sensor signals may indicate the presence of button activity such as press and release events. In response to detected button activity or other activity in the device, actuator drive signals may be generated for controlling the actuator. The user may supply settings to adjust signal processing and tactile feedback parameters.
1. A touch pad, comprising:
a cover layer forming a touch surface of the touch pad;
a printed circuit board having a capacitive sensor configured to detect a touch input to the cover layer by a user of the touch pad, the capacitive sensor coupled to the cover layer by an adhesive layer;
a set of force sensors positioned below and coupled to the printed circuit board and configured to produce a variable output that corresponds to an amount of force applied to the touch surface when the touch input is received; and
an actuator configured to apply a lateral force to cause the cover layer to shift in plane in response to, and based at least in part, on the amount of force applied to the touch surface when the touch input is received.
2. The touch pad of claim 1 , further comprising:
an array of sensor electrodes disposed on the printed circuit board and extending across an active surface of the touch pad.
3. The touch pad of claim 1 , wherein the adhesive layer includes a pressure-sensitive adhesive.
4. The touch pad of claim 1 , wherein:
the cover layer comprises a glass sheet; and
the touch pad further comprises an ink layer positioned between the glass sheet and the printed circuit board.
5. The touch pad of claim 1 , wherein each force sensor in the set of force sensors includes a strain gauge configured to produce the variable output that corresponds to the amount of force applied to the touch surface.
6. The touch pad of claim 1 , wherein the printed circuit board is rigid.
7. The touch pad of claim 1 , wherein the set of force sensors comprises capacitive force sensors.
8. The touch pad of claim 1 , wherein the set of force sensors comprises resistive force sensors.
9. An input device, comprising:
a cover layer;
a capacitive touch sensor array disposed under the cover layer and configured to detect a touch input to the cover layer;
an adhesive layer coupling the capacitive touch sensor array to the cover layer; and
an array of force sensors positioned below the capacitive touch sensor array and configured to produce a variable output that corresponds to an amount of force applied to the cover layer during the touch input; and
a linear actuator configured to cause the cover layer to laterally shift in response to the touch input to provide a haptic output in response to the force applied to the cover layer during the touch input.
10. The input device of claim 9 , further comprising:
a signal processor that interprets a magnitude of the variable output, greater than a force threshold, as a button-type press.
11. The input device of claim 9 , further comprising:
signal processing circuitry that interprets a predetermined sequence of touch sensor signals received from the capacitive touch sensor as a gesture, and interprets a predetermined magnitude of the variable output as a button-type press.
12. The input device of claim 11 , further comprising:
signal processing circuitry that interprets multiple predetermined parallel sequences of touch sensor signals received from the capacitive touch sensor as a pinch gesture.
13. The input device of claim 9 , further comprising:
signal processing circuitry that interprets a time-dependent variance in the variable output as a gesture.
14. The input device of claim 9 , wherein the array of force sensors comprises capacitive force sensors.
15. The input device of claim 9 , wherein the array of force sensors comprises piezoelectric force sensors.
16. An input device, comprising:
a dielectric outer layer;
a force-sensitive structure below the dielectric outer layer and comprising:
a resilient body;
a first electrode disposed on a first surface of the resilient body; and
a second electrode disposed on a second surface of the resilient body, positioned opposite to the first electrode, and capacitively coupled to the first electrode; and
an actuator coupled to the dielectric outer layer and configured to apply a lateral force to the dielectric outer layer in response to a signal; wherein in response to a force applied to the dielectric outer layer, the resilient body compresses and a capacitance between the first electrode and the second electrode increases in proportion to a magnitude of the force.
17. The input device of claim 16 , wherein a button-type press is indicated when the magnitude of the force exceeds a force threshold.
18. The input device of claim 16 , wherein the dielectric outer layer is opaque.
19. The input device of claim 16 , further comprising an opaque layer positioned under the dielectric outer layer.
20. The input device of claim 16 , wherein the dielectric outer layer comprises plastic.