Information handling system touch detection device grounding and self-test
An information handling system includes a touchpad that accepts touch inputs to move a cursor on a display and that deflects at a front side to accept button inputs. A bracket is disposed between a touch detection surface and circuit board of the touchpad to bias the touch detection surface up and deflect in response to a push down as a button input. Conical spring ground devices coupled to the circuit board on opposing sides of the bracket interface with an ohmmeter included on the circuit board that detects a resistance from a first ground device through the system ground to a second ground device. Resistance across ground is applied by the touchpad processor to adjust touch detection sensitivity and avoid ghost inputs.
1 . An information handling system comprising:
a housing;
a processor coupled in the housing and operable to execute instructions to process information;
a memory coupled in the housing and interfaced with the processor, the memory operable to store the instructions and information;
a touch detection surface coupled to the housing and interfaced with the processor, the touch detection surface interfaced with a circuit board having a processing resource, the circuit board grounded to the housing at opposing sides;
an ohmmeter circuit coupled to the circuit board and interfaced with the processing resource, the ohmmeter circuit configured to measure resistance between the grounds at the opposing sides through the housing.
2 . The information handling system of claim 1 wherein the touch detection surface further comprises:
a bracket coupled to the housing at the opposing sides and disposed between the touch detection surface and the circuit board;
wherein the touch detection surface accepts button presses by deflection of the bracket from a press at the touch detection surface.
3 . The information handling system of claim 2 further comprising:
a first spring biased from the circuit board at a first side and aligned against a first position of the housing, the first spring interfaced with ground of the circuit board; and
a second spring biased from the circuit board at a second side and aligned against a second position of the housing, the second spring interfaced with ground of the circuit board.
4 . The information handling system of claim 3 wherein the first and second springs comprise conical springs of conductive material.
5 . The information handling system of claim 4 wherein the touch detection surface comprises a capacitive touch detection surface.
6 . The information handling system of claim 1 wherein the processing resource applies the resistance to adjust sensitivity of the touch detection surface.
7 . The information handling system of claim 6 wherein the ohmmeter circuit integrates within the processing resource.
8 . The information handling system of claim 7 further comprising:
a first spring biased from the circuit board at a first side and aligned against a first side of a bracket disposed between the touch detection surface and the circuit board, the bracket coupled to the housing, the first spring interfaced with ground of the circuit board; and
a second spring biased from the circuit board at a second side of the bracket and aligned against a second side of the bracket, the second spring interfaced with ground of the circuit board.
9 . A method for managing touch inputs at a touchpad integrated in a portable information handling system, the method comprising:
grounding the touchpad at a first side with a first ground device interfaced with a housing of the information handling system;
grounding the touchpad at a second side with a second ground device interfaced with the housing of the information handling system;
measuring at the touchpad a resistance from the first ground device through the housing to the second ground device;
detecting touches at a touch detection surface of the touchpad with a processing resource interfaced with the touch detection surface;
applying the measured resistance with the processing resource to adjust a sensitivity of the touchpad touch detection surface.
10 . The method of claim 9 wherein the measuring a resistance is performed with an ohmmeter integrated in the processing resource.
11 . The method of claim 9 further comprising:
coupling a bracket to the housing between the touch detection surface and a circuit board having the processing resource; and
grounding the touchpad at the first and second sides to contact a housing of the information handling system to first and second grounding devices coupled to the circuit board.
12 . The method of claim 11 wherein the ground devices comprise conical springs coupled to the circuit board.
13 . The method of claim 12 further comprising:
pressing down on a front side of the touch detection surface to deflect the bracket; and
in response to deflection of the bracket, applying a button press input.
14 . The method of claim 13 wherein the touch detection surface comprises a capacitive touch detection surface.