Quantum Research Group has released an enhanced version of its QWheel chip, the QT511. It features low power consumption, enhanced operation under difficult sensing conditions and the ability to place a mechanical button in the center of the scroll wheel without experiencing false detects on operation.
QWheel touch wheel technology is effectively a 'capacitive potentiometer', where the wiper is a finger. The electrode consists of a simple resistive ring element placed behind the plastic panel; three capacitive QT sensing channels are connected to this ring, and the signals processed to 7-bits of absolute position. The result is output on an SPI serial interface. The device can be set to sense through panels up to 3-mm thick, and even through gloves. The entire circuit with the electrode ring can be fabricated on a single-sided PCB. In many cases it claimed to be less expensive than mechanical equivalents and more reliable.
QT510 uses spread-spectrum modulation for high immunity to external noise sources and ultra-low RF emissions. It also features drift compensation to account for slow changes due to aging or environmental conditions. It will also operate in a low power microamp mode. Prox mode allows the device to detect hand movement up to 50 mm away from the panel surface; this can be made to activate a display or product from standby, before the user even touches the product.
Contact info: Quantum Research Group
651 Holiday Drive Bldg. 5/300
Pittsburgh, PA 15220