Multifunction input device with an embedded capacitive sensing layer
Disclosed herein is a multifunction input device, such as, a keyboard. The multifunction input device has a capacitive sensing layer that enables a user to use the multifunction input device as standard keyboard and also as a touch sensitive surface such as, for example, a trackpad.
1. A keyboard, comprising:
an array of keys, each key of the array of keys comprising:
a keycap;
an actuation mechanism coupled to the keycap and configured to move the keycap between an unactuated and an actuated position; and
a switch disposed beneath the keycap and comprising a dome that is configured to contact an electrical contact when the keycap is in the actuated position;
a frame defining an array of openings, each key of the array of keys positioned in a respective opening; and
a capacitive sensing layer disposed below the frame and the array of keys, the capacitive sensing layer configured to detect a touch input across multiple keys of the array of keys and one or more portions of the frame, wherein for each key of the array of keys:
the capacitive sensing layer defines a void space beneath the keycap in which the electrical contact is positioned; and
at least one sense electrode and at least one drive electrode of the capacitive sensing layer are arranged around a periphery of the void space.
2. The keyboard of claim 1 , wherein the capacitive sensing layer is calibrated to normalize a detected change in capacitance over the keycap and at least a portion of the frame.
3. The keyboard of claim 1 , wherein the at least one sense electrode comprises a protrusion extending into the void space.
4. The keyboard of claim 1 , further comprising a fabric layer positioned over the keycap.
5. The keyboard of claim 4 , wherein the fabric layer comprises an embossed portion that extends beyond a surface area of the keycap and operative to provide a smooth transition between the frame and the surface area of the keycap.
6. The keyboard of claim 4 , wherein the fabric layer defines recesses between respective keys of the array of keys.
7. The keyboard of claim 1 , wherein a portion of the at least one sense electrode is interleaved with a corresponding portion of the at least one drive electrode.
8. The keyboard of claim 1 , further comprising a substrate, wherein the capacitive sensing layer is embedded in the substrate.
9. An input device, comprising:
a frame defining first and second openings and a frame segment positioned between and at least partially defining the first and second openings;
a first key positioned in the first opening and defining a first input surface;
a second key positioned in the second opening and defining a second input surface, each of the first and second keys comprising:
a keycap configured to actuate in response to a key input; and
an electrical contact positioned beneath the keycap and configured to provide a signal in response to an actuation of the keycap; and
a capacitive sensing layer positioned below the frame and configured to detect a touch input along the first input surface, the second input surface, and at least a portion of the frame segment.
10. The input device of claim 9 , wherein the capacitive sensing layer is calibrated such that a detected change in capacitance is normalized over the first input surface and the second input surface.
11. The input device of claim 9 , wherein a portion of the capacitive sensing layer is coupled to the frame of the input device.
12. The input device of claim 9 , wherein the capacitive sensing layer is operative to distinguish a first type of input from a second type of input received along the first input surface, the second input surface, and the at least the portion of the frame segment.
13. The input device of claim 9 , further comprising a fabric layer disposed over the keycap.
14. A method for detecting a touch input received across multiple keys and a portion of a frame of a touch-sensitive keyboard, comprising:
in response to receiving a first portion of the touch input along a first key of the touch-sensitive keyboard, detecting a first change in capacitance in a first region of a capacitive sensing layer located beneath the first key, the first key comprising an electrical contact positioned in the first region and configured to provide a signal indicating actuation of the first key;
in response to receiving a second portion of the touch input along a frame segment of the touch-sensitive keyboard, detecting a second change in capacitance in a second region of the capacitive sensing layer located beneath the frame segment, wherein the first region is different from the second region;
in response to receiving a third portion of the touch input along a second key of the touch-sensitive keyboard, detecting a third change in capacitance in a third region of the capacitive sensing layer located beneath the second key of the touch-sensitive keyboard; and
adjusting an output signal of the capacitive sensing layer to normalize the first change in capacitance with respect to at least one of the second change in capacitance or the third change in capacitance.