Optical force sensing - Multi-modal control
Innovative switching technologies are transforming controls on electric devices to be sensitive, multimodal, reliable, hygienic, stylish, and cost-effective.
Interfaces for a superior and more intuitive usability
In our everyday routines, we frequently interact with various controls—pressing a button to call an elevator, swiping to adjust music volume, or toggling switches to illuminate a room. These actions are so ingrained in our lives that we seldom pause to consider the mechanics or reliability behind them.
Conventional human-operated controls, such as mechanical, electro-mechanical, capacitive, or magnetic implementations, often require significant design efforts on the device surface, limiting usability. For instance, mechanical buttons like elevator controls demand extra measures to ensure functionality and durability without hindering cleaning or disinfection.
Additionally to the demands of a button, the challenge intensifies in space constrained applications, like the side buttons on a smartphone, where water resistance and compact design counts.
Optical force sensing from ams OSRAM enables new possibilities for multimodal controls, also featuring context-sensitive appearance. The sensor measures precisely the force applied on the surface (soft-, medium- and hard presses) and in combination with infrared-transparent surfaces, it is able to support touch, and proximity functions.
Optical force sensing can be easily integrated into almost any surface by measuring deformation due to the applied force on a plain control panel, suitable for applications that require exceptional precision and reliability without adding design-complexity or occupying much space. Surface panels using optical force sensing-based interfaces are highly reliable due to ensuring functionality even in harsh situations (e.g: dirt, water, and operating with gloved fingers). With its ultra compact design and precise sensing ams OSRAMs optical force sensing solution empowering sophisticated control panel designs, combining style, durability, and cost savings.
How optical force sensing works
Optical components provided from ams OSRAM are the heart of optical force sensing with the unique ability to enable for ultra-compact designs with while measuring highly precise human interaction with a multimodal touch control measuring. The functionoperating principle consists of an LED emitter and photodetector pair in a time-synchronized measurement cycle and in an optically isolated in one package.
The LED emits short pulses of light, which are back-reflected from the surface and collected by the photodetector. If there is a mechanical force applied to the surface by pressing the control, it causes a microscopic deformation which alters the amount of back-reflected photons seen by the photodetector. The less space there is between emitter and photodiode, the better the signal behaviorresolution. Optical force sensing from ams OSRAM provides this solution in one package to ensure highly reliable and accurate measurement.
This sensing solution can detect a deformation in of down to 1 µm, which enables operations also with rigid materials such as metal, stone or or glassglass. Depending on the mechanical properties of the chosen surface, the user can define an optical threshold, above which the change in photon flux is even possible to distinguish switching action.
Even wUsed with IR semi-transparent surfaces in combination with near-infrared light, the high sensitivity of ams OSRAM integrated optical force sensors also allows for so called zero-force operations, which is a perfect fit for optical touch, sliders or even proximity-based activation of the seamlessly integrated user interface for “shy-tech” design.
Optical force
Optical force sensor measures the deformation of µm on the infrared reflective surface while the user pushing it. Thus, the force intensity (soft-, medium- or hard-push) is reliable detected by the sensing system.
Optical touch
With semi-transparent surfaces and near-infrared light, the optical force sensor can also detect when the surface is touched without pushing (zero-force activation).
Proximity
Optical force sensors in combination with semi-transparent surfaces and near-infrared emitter can measure touchless the presence of a user. This function can enable context-sensitive switch appearance for focus control or let the control vanish when it is not needed.
Benefits
- Design of control elements which require defined force levels to qualify for intended activation
- Supports any non-transparent surface materials incl. metal
- Provides inherent galvanic isolation and maximum immunity to EMI / ESD
- Flexibility in layout & function of control elements with option for seamless transitioning between discrete button or continuous slider operation; supports even multi-level controls according to applied force
- Cost efficient BoM and end-product assembly as surface does not require electrical contact to PCB
- Extended use-case in combination with semi-transparent surfaces for optical touch or proximity based controls
- Unlocks maximum redundancy in functional safety critical designs, when paired with capacitive sensing technologiesCompact