Trackpad with force sensing circuitry
According to one aspect, a trackpad includes: a substrate; a stiffener plate; a circuit board between the substrate and the stiffener plate, the circuit board comprising position detecting circuitry configured to detect a position of an object adjacent the substrate, the circuit board including an inductive element; a grounding element that electrically connects the stiffener plate and the circuit board to each other; and force sensing circuitry configured to detect force applied to the substrate, the force detected using the inductive element.
1. A trackpad comprising:
a substrate;
a stiffener plate;
a circuit board between the substrate and the stiffener plate, the circuit board comprising position detecting circuitry configured to detect a position of an object adjacent the substrate, the circuit board including an inductive element;
a grounding element that electrically connects the stiffener plate and the circuit board to each other;
force sensing circuitry configured to detect force applied to the substrate based on a change of inductance related to the inductive element;
a housing enclosing the substrate, the stiffener plate, the circuit board, the grounding element, and the force sensing circuitry; and
a planar spring comprising:
a first fastening portion at the housing;
a second fastening portion at the stiffener plate;
a bias portion located between the first fastening portion and the second fastening portion, the bias portion being configured to bear against the stiffener plate; and
a 180-degree turn between the bias portion and at least one of the first fastening portion and the second fastening portion,
the planar spring being configured to facilitate a change in distance between the housing and the stiffener plate based on the force applied to the substrate.
2. The trackpad of claim 1 , further comprising an actuator configured to generate haptic output.
3. The trackpad of claim 2 , further comprising a fastener that secures the actuator to the circuit board.
4. The trackpad of claim 3 , further comprising a self-clinching nut mounted to the circuit board, wherein the fastener is coupled to the self-clinching nut.
5. The trackpad of claim 1 , further comprising a protective layer covering the inductive element.
6. The trackpad of claim 1 , wherein the inductive element comprises a coil.
7. The trackpad of claim 6 , wherein the coil comprises a planar spiral positioned flat against a main surface of the circuit board.
8. The trackpad of claim 7 , wherein the planar spiral comprises a copper trace of the circuit board.
9. The trackpad of claim 1 , wherein the grounding element comprises multiple rectangular metal elements in contact with the stiffener plate and the circuit board.
10. The trackpad of claim 1 , wherein the bias portion is wider than connections between the bias portion and the first and second fastening portions, respectively.
11. The trackpad of claim 1 , wherein each of the first and second fastening portions is aligned with a respective edge of the stiffening plate, the edges adjacent and perpendicular to each other.
12. The trackpad of claim 1 , further comprising a further grounding element that electrically connects the stiffener plate and the housing to each other.
13. The trackpad of claim 12 , wherein the further grounding element has a spiral shape.
14. An electronic device comprising:
a housing;
a trackpad mounted to the housing, the trackpad comprising:
a substrate;
a stiffener plate; and
a circuit board between the substrate and the stiffener plate, the circuit board comprising position detecting circuitry configured to detect a position of an object adjacent the substrate, the circuit board including an inductive element;
a planar spring between the stiffener plate and the housing, the planar spring comprising:
a first fastening portion at the housing;
a second fastening portion at the stiffener plate; and
a bias portion configured to bear against the stiffener plate, the bias portion being located between the first fastening portion and the second fastening portion,
the planar spring being S-shaped across the first fastening portion, the portion, and the second fastening portion, and facilitating a change in distance between the stiffener plate and the housing based on a force applied to the substrate; and
force sensing circuitry configured to detect the force using the inductive element.
15. The electronic device of claim 14 , wherein the planar spring comprises a 180-degree turn between the bias portion and at least one of the first and second fastening portions.
16. The electronic device of claim 15 , wherein the planar spring comprises a first 180-degree turn between the bias portion and the first fastening portion, and a second 180-degree turn between the bias portion and the second fastening portion.
17. The electronic device of claim 14 , wherein the bias portion is wider than connections between the bias portion and the first and second fastening portions, respectively.
18. The electronic device of claim 14 , wherein each of the first and second fastening portions is aligned with a respective edge of the stiffening plate, the edges adjacent and perpendicular to each other.
19. The electronic device of claim 14 , further comprising an actuator configured to generate haptic output, a self-clinching nut mounted to the circuit board, and a fastener coupling the actuator to the self-clinching nut.
20. The electronic device of claim 14 , further comprising a first grounding element that electrically connects the stiffener plate and the housing to each other.
21. The electronic device of claim 20 , wherein the first grounding element has a spiral shape.
22. The electronic device of claim 20 , further comprising a second grounding element that electrically connects the stiffener plate and the circuit board to each other.
23. A trackpad comprising:
a substrate;
a stiffener plate;
a circuit board between the substrate and the stiffener plate, the circuit board comprising position detecting circuitry configured to detect a position of an object adjacent the substrate, the circuit board including an inductive element;
a grounding element that electrically connects the stiffener plate and the circuit board to each other;
force sensing circuitry configured to detect force applied to the substrate based on a change of inductance related to the inductive element;
a housing enclosing the substrate, the stiffener plate, the circuit board, the grounding element, and the force sensing circuitry; and
a planar spring comprising:
a first fastening portion at the housing;
a second fastening portion at the stiffener plate; and
a bias portion located between the first fastening portion and the second fastening portion, the bias portion being configured to bear against the stiffener plate,
the planar spring being S-shaped between the first fastening portion and the second fastening portion, the planar spring being configured to facilitate a change in distance between the housing and the stiffener plate based on the force applied to the substrate.