SID: Single layer technology boosts capacitive touchscreens - Embedded.com

SID: Single layer technology boosts capacitive touchscreens

Cypress Semiconductor Corp. has developed what its calls a true single layer enabling technology for its TrueTouch touchscreen controllers and is revealing details at this weeks Society for Information Display  conference in Los Angeles.

Traditional capacitive touchscreens use a two-layer sensor to deliver the accuracy and linearity required for today’s user experience. Cypress has developed proprietary algorithms that interface with a true single-layer sensor with no bridges to deliver two-layer performance for an unparalleled combination of user experience and cost sensitivity.

The removal of this second sensor layer can save mobile device manufacturers 30 percent or more on sensor costs, and is available for glass and film.

According to John Carey, Director of Touchscreen Marketing at Cypress, what has been described as single layer technology uptill now has been based on a manufacturing technique that uses diamondand snowflake patterns require a layer of insulator and an expensive bridge – see graphic on right.

Cypress says that even with only one sensor layer, the TrueTouch solution delivers accuracy better than 1.25 mm, good signal-to-noise ratios, a response time of 80Hz, and active power of 3.6mW.

The technology is used in the Cypress CY8CTST241 (single-touch with one-finger gestures) and CY8CTST242 (adds limited two-finger gestures such as 'pinch' and 'zoom') delivers improved performance touchscreen accuracy of around 1mm and responsiveness with a true single-layer sensor panel, reducing the cost of the most expensive component of the touchscreen.

The controllers should enables manufacturers of handsets, cameras, GPS systems and other mobile systems to use capacitive touchscreens at the lower resistive touchscreen costs.

Capacitive advantages over resistive touchscreens include a more intuitive user experience, better transmissivity, lower power, increased reliability and better durability. According to Carey,  many lower-priced feature phones do not offer capacitive touchscreens today because of the cost. “The new TrueTouch single-layer sensor opens up new 'feature phones and lower-cost smartphones to capacitive touchscreens, especially in major markets such as China and India.”

The controllers are suitable for screen sizes of 2.0 to – 3.5 inches and Carey says that multiple devices could be used for larger touchscreens and Cyrpress has a history of moving from multi-controller implementations to single device solutions. The company's CY8CTMA884 is a single-chip tablet solution for touchscreens up to 11.6 inches.

The CY8CTST241 and CY8CTST242, which both provide QWERTY keyboard support, are available today for lead customers in QFN and CSP packages. The CSP measures 2.2mm x 2.32mm and has 30 balls.  Active power is 3.6mW,  low power current is 0.7mA, deep sleep current is 100nA and the refresh rate is 110Hz.

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