Sensing Principle


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Sensing Principle ®

Microchip’s GestIC Technology is a patented 3D sensor technology which utilises an electric field (E-fields) for advanced proximity sensing. It allows realisation of new user interface applications by detection, tracking and classification of a user’s hand or finger motion in free-space.

E-field Basics An E-field is generated are generated by electrical charges and spread three-dimensionally around the surface carrying the electrical charge. Applying direct voltages (DC) to an electrode results in a constant electric field. Applying alternating voltages (AC) makes the charges and, thus, the field, vary over time. When the charge varies sinusoidal with frequency f, the resulting electro-magnetic wave is characterised by wavelength λ =c/f, where c is the wave propagation velocity in vacuum the speed of light.

How does it work? GestIC® technology uses transmit (Tx) frequencies f in the range of 100 kHz, which reflects a wavelength of about three (3) kilometers. With electrode geometries of typically less than twenty (20) by twenty (20) centimetres, this λTx wavelength is much larger in comparison. Therefore, the magnetic component is practically zero and no wave propagation takes place. The result is a quasi-static electrical near field that can be used for sensing conductive objects such as the human body.

Once a user intrudes the sensing area, the electrical field distribution becomes distorted. The field lines intercepted by the hand are shunted to ground through the conductivity of the human body itself. The simulation results in Figure 1 and Figure 2 show the influence of an earth grounded body to the electric field. As illustrated, the proximity of the body causes a compression of the equipotential lines and shifts the receiver (Rx) electrode signal levels to a lower potential which is detected by the respective GestIC® technology product.

GestIC®Technology System The GestIC® technology system is comprised of the respective GestIC® chip which is connected to sensing electrodes to determine the fluctuation pattern of the electrical field (E-field).

Sensing Electrodes With MGC3130 using a number of typically four receiver (Rx) electrodes, the origin of E-field variations inflicted by the user's hand can be detected. Those electrode signals are processed by the GestIC® technology device to calculate the hand position relative to the sensing area in x, y, z data points, and classify the movement pattern into gestures in real time.

Electrode Materials Examples for electrode materials:

Rigid printed circuit (PCB) electrodes Flexible printed circuit (FPC) electrodes Self adhesive electrodes Laser direct structured electrodes (LDS) Conductive foils

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Microchip’s GestIC® technology utilises low-cost and thin sensing electrodes made of any conductive material. It allows an invisible integration behind the target device’s housing while the overall thickness of the product’s industrial design is not increased. Even the reuse of existing conductive structures, such as a display’s Indium Tin Oxide (ITO) coating, is feasible making GestIC ® technology a very cost effective system solution. To learn more about the design and integration of GestIC® technology sensing electrodes, please see the System Design Guide.

GestIC® Technology Colibri Gesture Suite Microchip's Colibri Gesture Suite is an easy-to-use library of GestIC® technology features. By analysing today’s user interfaces, Microchip has developed the suite to be functional, intuitive, and fun. For ease of use, the features are pre-processed on-chip to allow manufacturers to realise powerful user interfaces with very low development efforts.

Gesture Classification

Colibri Benefits hhjvhdfjh

The Colibri suite uses a Hidden Markov model (HMM) in conjunction with  x/y/z hand-position vectors. It provides  the highest user independent recognition  rates of 3D hand and finger gestures.

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On-chip, ready-to-use suite Sophisticated Hidden Markov model Highest recognition rate Optimised for most intuitive gestures Fast design and time to market success for developers. Real-time features, running concurrently Customisable per individual OEM request

Key Features The Colibri Suite features high resolution x/y/z hand position tracking, flick, circle and symbol gestures to perform input commands such as open application, point, click, zoom, scroll, mouse-over and many others without the need to touch the device.

Mobile Friendly and Always-On Approach Detection is a programmable function that scans for user activity while the chip is in self wake-up mode. If real user interaction is detected, the system automatically switches into full sensing mode and alternates back to wake up mode once the user leaves the sensing area. As a result, always-on 3D gesture sensing becomes reality even for battery powered products.