Wednesday, June 6, 2012

TouchTurns: A US-Based P-Cap Module Startup

TouchTurns, a nine-person projected-capacitive (p-cap) touch module startup in Santa Clara, CA, is going after a market that is without question currently underserved: commercial p-cap applications in the US. TouchTurns’ differentiation derives from several interesting aspects, as follows:

1. The particular sensor being exhibited by TouchTurns (in 3.5”, 5” and 7” sizes) uses a single layer of ITO without bridges or metal routing traces, yet it uses mutual capacitance, not self-capacitance. This is accomplished by running drive electrodes vertically down the sensor and forming individual sense pads in a column beside each drive electrode. This also allows the sensor to be borderless on three sides! The photo below shows a close-up of the FPC on the top edge of a 3.5-inch sensor; you can see from the trace pattern that there are 10 drive electrodes and 15 sense electrodes per drive electrode.

Photo by author

2. The sensor is built on a substrate of Corning’s 0.1 mm “Willow” glass, using laser ablation for patterning (no photolithography!). Laminating the sensor to a 0.5 mm cover-glass with 0.1 mm of OCA yields a total stackup of 0.7 mm. This is about the same thickness as a “sensor-on-lens” configuration, but without the yield issues of that configuration (which, from the rumors I’ve heard, are significant).

3. The sensor can be driven by popular p-cap controller ICs with TouchTurns custom firmware and sensor patterns. The resulting module specs appear to be in the ballpark of the Microsoft 8 Touch Logo (10 touches, <1 mm accuracy error, 12 mm minimum between fingers, ~100 Hz scan rate, etc.) – although meeting the Logo spec is typically unimportant in commercial applications.

4. TouchTurns has a complete prototype line in Santa Clara for quick-turn development builds, and an offshore partner (CN Innovations in Shenzhen) for low-cost mass production. The prototype line is capable of building a wide range of sensor architectures, as well as printing custom artwork on custom-shaped cover-glass.

These four aspects make TouchTurns highly competitive in a market that I believe will welcome it with open arms. You can find TouchTurns in the Corning booth (123), to the right of the big roll of Willow glass.-- Geoff Walker, Walker Mobile, LLC.

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