Technical details

Alterix Ltd is now offering a Windows 8 certified electronic solution for large size capacitive multi-touch digitisers - helping to replace interactive whiteboards with modern multi-touch screen TVs.

By rejecting the touches initiated by large objects, our electronics enables users to draw with a stylus or type using a virtual keyboard while resting their hand or arm on the surface of the screen, thus eliminating the main cause of 'Gorilla-arm' syndrome.

Individual measurements are combined to build a surface map of the capacitive coupling to the grounded objects. This map translates into a 2D image of conductive objects like multiple fingers, palm, arm, stylus, or even a mug or a mobile phone located on the top of the screen.

Multi-touch displays with diagonal sizes smaller than 50" can be served by our electronics with a refresh rate of 200 Hz reporting up to 15 simultaneous touches. At much larger diagonal sizes, such as 105", the refresh rate is reduced to 100 Hz while the maximum number of touches reported to the PC is increased to 40 simultaneous touches.


The image is processed within the electronics in order to reject touch events from large objects and to calculate and send to the computer the relevant information about individual touches initiated by either fingers or a stylus.

Via a manufacturing license agreement for embedded software and hardware we provide access to the software in the form of object code and will supply manufacturing documentation for the reference design of the electronics adjusted for different geometries according to the specification provided by the client.

Touch position is reported together with its accurately estimated size, thus allowing the application software to distinguish the smaller area stylus inputs from the larger area finger touch inputs.


Significant improvement in the signal-to-noise ratio compared to the competitive solutions allows the processing of measurements at a rate of up to 8,000,000 per second in order to scan the nodes of the capacitive sensor grid. By using readily available off-the-shelf components we are able to keep the production cost for the electronics below $50 for a 105” display system, with a sensing grid structure made up of 600 detection and excitation channels.

The cost of the electronics scales down with the diagonal size of the digitizer and the number of total channels in the sensing grid. For example, for a sensing grid made up of 205 detection and excitation channels - suitable for 34" diagonal size ultra-wide monitor - the build cost of the electronics is below $20.