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UW researchers turn LCDs into touchscreen

Two UW researchers have found a way to turn any LCD monitor into a touchscreen. While it may sound complicated, all it takes is a few algorithms and a $5 sensor that plugs into the wall.

Doctoral students Ke-yu Chen and Sidhant Gupta work in the Ubiquitous Computing Lab on campus. They came up with the idea for their project, uTouch, while working on a similar project called LightWave that tested how the energy given off by any electronic devices in someone’s house and even by the human body can be manipulated to control an electronic device. The energy, called electromagnetic interference (EMI), is what caused a light bulb to dim and brighten as they moved their hands closer and farther away from the bulb. 

“We thought that the monitor could have a similar effect,” Chen said. 

It did. Chen said an LCD monitor radiates EMI, also called noise, to the power line when it is turned on. The EMI increases as the human hand approaches the screen, and uTouch captures the EMI variations and uses them as signals to detect a touch gesture.

“This technology can provide a simple way to talk to the computer,” Chen said.

The technology is not perfect, but if the sensor is plugged in and the software is installed, the software can read the fluctuations in EMI and determine if the interference is caused by one of the five gestures or the types of touches it is set to respond to. 

“Sometimes in life, we need something simple,” Chen said. “Even though it might not be perfect.”

Gupta explained that the technology is cheaper and less wasteful than buying new screens because it simply modifies old technology. He said it may be useful in places with many LCD screens that people wish to upgrade at a lower cost. Gupta and Chen traveled to Paris to present the technology at a computer-human interaction conference in Paris.  

“Imagine a museum that already has a large number of LCDs, and they would want to make these displays interactive. Buying or upgrading these screens with touch sensors individually would be very costly,” Gupta said in an email. “On the other hand, uTouch sensor simply plugs into the wall and will allow these existing LCDs to be touch sensitive.”

However, there is still work to be done. There are no current plans to market the technology, but Gupta said there is enough information in their paper for anyone interested to try to build the technology on their own using the algorithms in the paper and off-the-shelf parts. The paper, available online, is titled: “uTouch: Sensing Touch Gestures on Unmodified LCDs.”

“People are free to use it,” Chen said. “It’s always good to reuse existing devices and enhance its functionalities in a low-cost and easy way.”  

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