Force enhanced input device
Methods and devices are described for operating an input device for an electronic system which includes a housing. The input device includes an input surface and a first substrate having a first plurality of sensor electrodes configured to sense input objects proximate the input surface, and a pair of force sensing electrodes on the bottom of the first substrate. The input device includes a second substrate having a planar spring plate including a perimeter region surrounding an interior region, the perimeter region including a leaf spring coupled to the housing, and a spacing layer configured to physically couple the interior region of the second substrate to the first substrate. A force applied to the input surface deflects the first substrate and the interior region relative to the perimeter region, changing a variable capacitance formed between the force sensing electrodes.
1. An input device for an electronic system having a housing, the input device comprising:
an input surface;
a first substrate including:
a first plurality of sensor electrodes configured to sense input objects proximate the input surface; and
at least one pair of force sensing electrodes disposed on a bottom side of the first substrate,
wherein the at least one pair of force sensing electrodes includes a first force sensing electrode configured to transmit a sensing signal and a second force sensing electrode configured to receive a resulting signal; and
a planar second substrate including a conductive region and a planar spring plate, the planar spring plate including a perimeter region surrounding an interior region, the perimeter region including a return mechanism configured to be physically coupled to the housing; and
a spacing layer disposed between and configured to physically couple the interior region of the second substrate and the first substrate,
wherein a force applied to the input surface results in a deflection of the first substrate and the interior region of the second substrate relative to the perimeter region of the second substrate,
wherein the deflection changes a variable capacitance formed between the conductive region and the at least one pair of force sensing electrodes,
wherein the variable capacitance includes a trans-capacitive coupling between the first force sensor electrode and the second force sensor electrode, and
wherein the perimeter region of the second substrate is a region of the second substrate that is coupled to the housing and is restricted from relative movement with respect to the housing when the force is applied to the input surface.
2. The input device of claim 1 , wherein the conductive region is in the perimeter region of the second substrate and is disposed on one of the perimeter of the spring plate and the return mechanism of the spring plate.
3. The input device of claim 1 , wherein the return mechanism comprises a plurality of leaf springs.
4. The input device of claim 3 , wherein each of the plurality of leaf springs comprises a single fold cantilever design.
5. The input device of claim 3 , wherein each of the plurality of leaf springs comprises a multiple folded cantilever design.
6. The input device of claim 1 , wherein the planar spring plate comprises a continuous sheet of metal.
7. The input device of claim 1 , wherein the second substrate is substantially rectangular and the return mechanism comprises four planar leaf springs disposed on four corners of the second substrate, respectively.
8. The input device of claim 1 , wherein the first substrate further includes a microelectronic component and the spacing layer includes an aperture substantially aligned with the microelectronic component.
9. The input device of claim 1 , wherein the spacer layer comprises a conductive via configured to ohmically couple the at least one conductive portion of the second substrate to a conductive portion of the first substrate.
10. The input device of claim 1 , wherein the input surface is glass, and the first substrate comprises one of a printed circuit board (PCB) and a polyethylene terephthalate (PET) film.
11. The input device of claim 1 ,
wherein the second substrate is configured such that a force applied to the input surface results in a deflection of the interior region of the second substrate relative to respective perimeter region of the second substrate to thereby change a variable capacitance formed between the second substrate and a first pair of force sensing electrodes.
12. The input device of claim 1 , wherein the first substrate further comprises a conductive coil configured for near-field communication, and wherein a ferrite material is disposed between the first substrate and the second substrate which substantially overlaps the conductive coil.
13. The input device of claim 1 , further comprising a processing system communicatively coupled to and configured to operate the first plurality of sensor electrodes to determine positional information for input objects proximate the input surface, the processing system further configured to operate the at least one pair of force sensing electrodes to determine force information for the input objects based on the variable capacitance.
14. The input device of claim 13 , wherein the processing system is further configured to determine respective individual forces applied by multiple objects to the input surface based on the positional information and the force information.
15. The input device of claim 1 , wherein the input surface comprises an untreated glass stiffener layer overlaid with a cosmetic mylar face sheet.
16. An input device for an electronic system, the input device comprising:
an input surface;
a housing including a conductive region;
a first substrate including:
a first plurality of sensor electrodes configured to sense input objects proximate the input surface; and
at least one force sensing electrode disposed on a top surface of the first substrate,
wherein the at least one pair of force sensing electrodes includes a first force sensing electrode configured to transmit a sensing signal and a second force sensing electrode configured to receive a resulting signal; and
a planar second substrate including a planar spring plate including a perimeter region surrounding an interior region, the interior region configured to be physically coupled to the first substrate with a spacing layer disposed between the interior region of the second substrate and the first substrate, the perimeter region including a return mechanism configured to be coupled to the housing,
wherein a force applied to the input surface results in a deflection of the interior region relative to the perimeter region,
wherein the deflection changes a variable capacitance formed between the conductive region and the at least one force sensing electrode and a conductive region of the housing,
wherein the variable capacitance includes a trans-capacitive coupling between the first force sensor electrode and the second force sensor electrode, and
wherein the perimeter region of the second substrate is a region of the second substrate that is coupled to the housing and is restricted from relative movement with respect to the housing when the force is applied to the input surface.
17. The input device of claim 16 , further comprising a processing system communicatively coupled to and configured to operate the first plurality of sensor electrodes to determine positional information for the input objects proximate the input surface, the processing system further configured to operate the at least one force sensing electrode to determine force information for the input objects based on a change in the variable capacitance.
18. An input device for an electronic system having a housing which includes a conductive region, the input device comprising:
an input surface;
a first substrate including:
a first plurality of sensor electrodes configured to sense input objects proximate the input surface;
a pair of transcapacitive force sensing electrodes disposed on the bottom side of the first substrate,
wherein the pair of transcapacitive force sensing electrodes includes a first force sensing electrode configured to transmit a sensing signal and a second force sensing electrode configured to receive a resulting signal; and
a conductive coil configured for near field communication; and
a planar second substrate including a conductive region and a planar spring plate, the planar spring plate including a perimeter region surrounding an interior region, the interior region configured to be mechanically coupled to the first substrate with a spacing layer disposed between the interior region and the first substrate, the perimeter region including a return mechanism configured to be coupled to the housing, wherein a ferrite material is disposed between the first substrate and the second substrate which substantially overlaps the conductive coil,
wherein a force applied to the input surface results in a deflection of the interior region relative to the perimeter region,
wherein the deflection changes a variable capacitance formed between the conductive region and the pair of transcapacitive force sensing electrodes,
wherein the variable capacitance includes a trans-capacitive coupling between the first force sensing electrode and the second force sensing electrode, and
wherein the perimeter region of the second substrate is a region of the second substrate that is coupled to the housing and is restricted from relative movement with respect to the housing when the force is applied to the input surface.