Multi-touch, high-speed, high noise immunity, low-voltage resistive touchscreen controllers

Rohm Semiconductor new BU21023/BU21024 series of high-speed, high noise immunity, low-voltage resistive touchscreen controllers are the industry’s first to enable multi-touch (two-point) operation and intuitive gesture control, including pinching, spreading and rotating – previously possible only with more expensive capacitive touch systems, the company said. The design can save power, Rohm told Control Engineering.

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Rohm Semiconductor BU21023 / BU21024 series of high-speed, high noise immunity, low-voltage resistive touchscreen controllers are now available. These new controllers are the industry’s first to enable multi-touch (two-point) operation and intuitive gesture control, including pinching, spreading and rotating – previously possible only with more expensive capacitive touch systems, the company said. The increasing functionality and sophistication of electronic devices drives the demand for touchscreens which are preferred for their ease of use and versatility. In addition they enable direct interaction without the need for input devices. Resistive touchscreens account for over 75% of the touchscreen market, due in large part to their lower cost and higher precision when compared to capacitive technologies. Another advantage is that they allow operation with fingernails or even while wearing gloves, unlike capacitive touchscreens that require a conductor or dielectric.

At Sensors Expo in Rosemont, IL, on June 7, Ruben Balbuena, Rohm senior product marketing manager, told Control Engineering that 8-bit internal preprocessing can perform many functions without waking the main processor for the device, saving power in mobile applications.

Those close to the development noted:

• Resistive touch screens are used on lots of industrial HMI applications.
• Capacitive devices don't work when gloves are worn or hands are wet or screen is dirty. Until now resistive touchscreen were limited to single touch operations, so common touchscreen gestures like pinch, spread, rotate, scroll were not possible.
• Industrial systems could see a dramatic increase in functionality without replacing the touchscreen by designing in this new controller IC. 

Nick Ikuta, Rohm senior technical marketing manager, said, “Touchscreen panels are used in a wide variety of applications, including cellular telephones and car navigation systems. The functionality of electronic devices is increasing day by day and operation by touch panel is increasingly shifting toward pinch, spread and other intuitive finger gestures. Until now, in order to actualize functions like these, electrostatic capacitance type touchscreens were the only choice. With the new BU21023/BU21024 series, conventional 4-wire resistive touchscreen designs can be easily expanded to include dual-touch.”

The BU21023/BU21024 series ICs integrate a dedicated analog circuit and CPU for precise two-point coordinate and gesture detection. A calibration function is also built-in that minimizes the effects of panel variations during production as well as fluctuations in touchscreen device characteristics caused by temperature variations or time-based degradation.

- Edited by Mark T. Hoske, Control Engineering, CFE Media, www.controleng.com

Also see www.controleng.com/HMI.