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[FAQ] How could you add force touch to a car's center information display/LCD assembly?

Other Parts Discussed in Thread: LDC3114-Q1, LDC1614-Q1

How would you be able to add inductive sensing to an LCD assembly to read the force of a user's touch on a car center console/information display?

  • Adding inductive force touch to an LCD assembly would be similar to implementing an inductive touch button. For basics on inductive touch buttons, please see the getting started with LDC touch buttons E2E FAQ.

    Using an LCD is common in modern car center consoles for the user to control settings like volume control or GPS. Many of these screens have capacitive touch to allow the user to interact with what is on the screen. This gives the system information about where the user is touching but some systems can benefit from knowing how hard the user is pressing on the screen or a redundant method for determining long presses. One way to add this information to the system is to have an inductive sensor like the LDC1614-Q1 or LDC3114-Q1 monitor the motion of the LCD assembly. Implementing an inductive sensor can be done by adding a thin strip of metal (like copper tape) to the bottom of the LCD assembly and adding some small springs to allow the assembly to move. Inductive sensing can detect μm levels of motion so the spring does not have to allow for much motion in the assembly. Here is one example of how this stackup could look:

    The inductive sensing coils are placed at the corners of the assembly to allow for detecting a press in the center versus the edge of the screen. This can also be useful to detect cases where a hand is used to press the screen instead of a finger. If the whole screen moves and all 4 coils detect a press equally, then it is likely an accidental press with a hand or a really hard press in the center of the screen. Either way, adding an LDC behind the assembly can provide additional functionality.

    Best Regards, 

    Justin Beigel