Shadow Sense vs. Ambient Lighting

IR-based Touchscreen Techonologies Ambient Lighting Rejection

Today, the discussion is about how IR-based touchscreen technologies reject ambient light and what makes ShadowSense different. Even though IR-based touchscreen technologies offer many advantages, as you may be aware, most infrared touchscreens do not do well in outdoor environments as the sun is a strong source of IR radiation. In addition, most IR-based touchscreen technologies also suffer from interference due to ambient lighting and indoor lights. These light sources have been known to saturate competing IR sensor technology products which ultimately degrades their performance.

ShadowSense vs. The Competitor

In a side-by-side comparison, we place a 500-watt halogen light over both a ShadowSense touchscreen panel and a competitor’s IR touchscreen panel. You will see that the standard IR touchscreen that uses beam break fails catastrophically. However, ShadowSense works seamlessly and without flaw. You might be asking yourself, how is this possible?

First, let’s discuss how the concept of beam break works. Beam break technologies utilize a number of IR beams, constituting LEDs and detectors. The LED shines the light, and when an object blocks the light [ie. A touch on a touchscreen] the beam would then be broken. The change in light is picked up by the detector and a touch event can be processed. But, in a brightly lit or sunlit environment, the immense amount of light pollution coming in from an external source ultimately leaks into the detector causing it to lose the breaking of the beam. The sun overpowers the LED and the detector does not function properly.

What makes ShadowSense different?

Baanto’s ShadowSense architecture is entirely immune to light pollution due to the nature of its patented technology. Did you know that Baanto’s ShadowSense has been granted 27 patents and has over 76 filed across nine different patent families? Our sensors operate in the analog domain, and our LEDs strobe with a specific signal frequency. Using hardware bandpass filters and tuner circuits at the sensor level, we can tune out all ambient interferences and focus only on the actual touch signal. Let’s simplify this a little more; think of how you can tune into a specific station on your radio while ignoring all the other transmissions on other frequencies.

Where ShadowSense differs is that we have our ShadowSensors and LEDs placed everywhere. Now instead of just turning on the LEDs, we blink/modulate them. These LEDs are modulated at a two-megahertz frequency, resulting in us looking for the flickering shadow. Going back to our patent portfolio, we have a tuner circuit at every detector tuning into the two-megahertz frequency. We really are tuning into a flickering shadow that is not created by any other light source. The result; room lights, sunlight and all the lights that generally attribute to light pollution in a touchscreen environment are eliminated.

Interested in learning more about how Baanto ShadowSense can help you? Get in touch with us today!

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