New STMicro Chip Seeks To Eliminate Touchscreen ‘Noise’

ST's FingerTip technology will reduce 'noise' from capacitive touchscreens

As touchscreens proliferate across an ever-growing number of gadgets so does the phenomenon of ‘false’ finger touches. This phantom stimulus, known within the consumer electronics industry as ‘noise’, is caused by a myriad of sources ranging from low-quality battery chargers to the way electricity is routed within displays to illuminate pixels.

The common element is that this electrical noise, which is measured in volts, frustrates gadget users, who may find that it prevents their devices’ “multitouch” touchscreens from recognizing their commands.

To stifle this white noise, Geneva-based STMicroelectronics, Europe’s largest chipmaker, has developed a new chip that it is calling FingerTip. The chip is designed to be mounted close to the display of a cellphone or tablet where it can communicate with a sensor embedded in the device’s touchscreen.

The position allows the chip to detect noise and then eliminate it using a digital signal processing engine, says Benedetto Vigna, the General Manager of STMicro’s sensors division. The company says device manufacturers are currently testing FingerTip and will likely release products with it before the end of the year.

The idea of inserting a noise-reducing chip into touchscreen devices isn’t new but STMicro says FingerTip offers more than existing chips by filtering out a greater amount of noise without consuming excessive battery power or slowing touchscreen reaction times. FingerTip has also been designed to work with both “on-cell” and “in-cell” touchscreen displays.

On-cell displays, so-called because they are composed of a touch-sensitive layer on top of the display, are more common today, but in-cell displays, which embed a sensing element into the pixels themselves, will become widespread in the future, says Vigna. STMicro says FingerTip is the first noise reduction chip that can manage both types of touchscreens.

FingerTip is part of STMicro’s wide-ranging interest in micro-sensors. STMicro Chief Executive Carlo Bozotti recently told Forbes that he hopes this business will soon generate $1 billion or about 10% of the company’s revenues.

FingerTip is meant to be the first product in a new line for STMicro’s MEMS [Micro-Electro-Mechanical Systems], Sensors and High Performance Analog Division, which Vigna oversees. “We want to enlarge our portfolio of touch sensors,” says Vigna. “FingerTip ensures we have a more complete offering of solutions.”

Though FingerTip builds upon STMicro’s experience in analog chips and MEMS sensors, it can be sold independently of the company’s other products. Vigna says FingerTip is not dependent on STMicro chips or sensors and can be used with any brand of capacitive touchscreen. The chip will support displays that are up to 10 inches in diameter – a range that accommodates most tablets.