Engineers have been trying to measure touch force as a means of determining touch location for nearly forty years but have been unsuccessful because of lateral (non-orthogonal) forces and complex signal processing requirements.

VISSUMO has solved these and other issues with a patent-pending beam structure and innovative algorithms. VISSUMO force panels can sense the X-Y location of a touch by accurately and reliably measuring the force being exerted at the touch location.

The physical parameter inherent in touch (force) is not directly measured by any of the commercial touch screen technologies on the market. In all cases, the force of a touch is converted to some other physical parameter, which is then measured. VISSUMO’s Force Panel Technology is the only touch technology that simply and directly measures the force of a person’s touch rather than using a complex indirect measurement.

How VISSUMO Force Panel Technology Senses Touch
The location and force of the user’s touch can be quickly and accurately determined by placing four force sensors near the corners of the touch surface. Touching the surface at the center imposes equal force on all four sensors while touching the surface towards a corner imposes greater force on the closest sensor and the least amount on the opposite sensor.

How VISSUMO Determines Touch Location
X-Y location is easily determined by using relatively simple math equations: X = (S3 + S4) / (S1 + S2 + S3 + S4) Y = (S1 + S3) / (S1 + S2 + S3 + S4)

How VISSUMO Determines Touch Force
±Z-axis force is easily determined with another simple equation: Force (touch) = -(S1 + S2 + S3 + S4)

An inexpensive DSP device performs the processing necessary to analyze the four force waveforms and generate an accurate touch location.