11.1 Force sensing, haptics and touchless extensions

Slide 72 of 157 · Force sensing, haptics and touchless extensions

Welcome to chapter 11: Force sensing, haptics and touchless extensions. I'm Diggy Breiling with FPD.DEV, The Future of Display and Systems Development. Our goal is to separate position sensing, force confirmation and feedback, and explain their integration tradeoffs. For help integrating touch and feedback into a custom embedded platform, contact FPD.DEV.

Slide 73 of 157 · Force is an additional measurement

A product can measure applied force using changes in resistance, capacitance, strain or a mechanical sensor arrangement. Some designs infer location from distributed force; others combine force measurement with a separate position sensor. For a simple static panel on supports, total applied normal force is approximately the sum of support reactions after tare. A force centroid can be inferred from force moments under ideal conditions. Preload, mounting friction, multiple contacts and acceleration complicate that model. Our animation is a one-contact teaching model. It illustrates a confirmation threshold, not a universal force-to-coordinate algorithm or a qualified safety function.

Slide 74 of 157 · Haptics is an output

A vibration actuator or piezoelectric element can provide tactile feedback after a recognized input. Feedback timing and strength influence whether the interface feels responsive. The haptic pulse confirms what the software decided; it does not prove that the intended command was selected. Ultraleap also demonstrates mid-air tactile sensation using focused ultrasound. This is a different feedback mechanism, typically paired with a separate way to locate the user's hand. Touchless selection changes interaction geometry and accidental-activation risks. For gloves or vehicle vibration, test whether the user can perceive and distinguish the intended feedback. An actuator that is obvious on a desk may be hard to recognize in service.

Slide 75 of 157 · Deliberate actuation without new confusion

Separate highlight, selection and execution in the user-interface definition. An illustrative sequence is: locate a contact, highlight a target, cross a defined force or confirmation condition, execute, then acknowledge. Specify cancellation and release behavior. Do not add a hard press merely because a sensor supports it. It may increase fatigue or make operation in motion harder. Compare it against a second confirmation step or a tactile physical control for the same task. Validate end-to-end behavior during repeated presses, long holds, interrupted power and missed feedback. Include users with different hand strength and reach.

Slide 76 of 157 · Apply the idea

A haptic click is felt but the commanded system does not change state. Has the command succeeded? Pause here and consider your answer. Not necessarily. The pulse may acknowledge only input recognition. The interface must distinguish touch acceptance, command transmission and confirmed system state.

Slide 77 of 157 · Chapter 11 complete

Complete the chapter exercise and review any open questions. Next is Chapter 12: LCD, OLED, microLED and other display architectures. I'm Diggy Breiling with FPD.DEV, The Future of Display and Systems Development. Thank you for joining me.

Not necessarily. The pulse may acknowledge only input recognition. The interface must distinguish touch acceptance, command transmission and confirmed system state.

Accuracy

Closeness of a reported coordinate to a defined reference position.

Precision

Repeatability or spread of results under specified conditions.

Resolution

Smallest coordinate increment or representable change; not equivalent to accuracy.

Latency

Time between explicitly defined input and output events.

PCAP

Projected capacitive touch; patterned electrodes sense electrical coupling changes.

Self-capacitance

Measurement of an electrode relative to an electrical reference.

Mutual capacitance

Measurement of coupling between transmit and receive electrodes.

Baseline

Reference measurement used to identify changes associated with touch.

SNR

Signal-to-noise ratio; specify the signal, noise measure and conditions.

SAW

Surface acoustic wave sensing through controlled propagation on a surface.

APR

Acoustic pulse recognition; a touch-generated mechanical response is used to locate contact.

DST

Dispersive signal technology; a bending-wave sensing implementation.

EMR

Electromagnetic resonance, used by compatible pen digitizers.

Haptics

Tactile feedback produced by the system.

HID

Human Interface Device class/protocol family; the descriptor defines report interpretation.

Report descriptor

Data describing the structure and meaning of HID reports.

Contact ID

Identifier used to distinguish and track a contact.

I2C

Two-wire synchronous bus; raw I2C communication does not itself implement HID.

SPI

Synchronous serial peripheral interface, with device-specific protocol behavior.

UART

Asynchronous serial hardware; electrical levels and framing must be specified.

Optical bonding

Joining optical layers with a transparent material to manage the interface.

Parallax

Apparent relative position shift caused by viewing separated planes from an angle.

NVIS

Night Vision Imaging System; pronounce 'en-vis' in this course.

Qualification

Evidence against a defined set of requirements for an identified configuration.

Validation

Evidence that the system satisfies its intended use.

Verification

Evidence of conformance to specified requirements.

Ghost touch

Reported contact that does not correspond to an intended physical touch.

Palm rejection

Classification or suppression of unintended hand contact.

On-cell / in-cell

Touch structures at a display-cell surface / integrated within the display structure; verify supplier construction.

Touch plane

Geometric region in which the sensing system detects an object.