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Perfect Timing: Synaptics’ TDsync

Mar 22, 2016

By Kevin Barber


The old expression “timing is everything” could very well have been predicting the future – smartphones, tablets, touchscreen computers, and cars’ instrument panels. The timing – more specifically, the synchronization – of those devices’ distinct touch and display functions plays a critical role in their speed, accuracy and overall user experience.

Because those intelligent devices incorporate both touch and display, those two functions sometimes find themselves in conflict with one another; a device’s clock cycle has a finite amount of bandwidth with which to accommodate both touch and display activity, the latter typically generating havoc-wreaking electrical noise. Moreover, their touch-sensing function is required to detect the presence of input sources other than a user’s bare hand, such as a gloved finger; a small, passive stylus; or a hovering object – any of which lessens the signal strengths.

Inaccurate touch sensing can cause inputs to be missed and also lead to an unintended touch or gesture. To put this in perspective, imagine accidentally sending a text message after auto-correct has its way with your words, or worse, the consequences of an unintended banking transaction. If not adequately mitigated, noise from the display can interfere with touch sensing.

Fortunately for intelligent-device designers, Synaptics’ TDsync technology was developed for just such mitigation. TDsync technology mitigates display-induced noise by separating touch sensing from the display-update period, allowing the touch sensing to occur precisely during a display “blanking” period -- a near noise-free juncture. TDsync technology, therefore, enables highly responsive touch sensing that is not influenced by display noise, and further improves the touchscreen’s ability to sense the weaker-signal objects, such as those cited above.

In addition to enabling touch sensing at display blanking periods, TDsync technology also allows for maintaining fast touch-sensing rates, even at higher display resolutions. Synaptics’ DDIC and TDDI products are designed with the capability to drive high-resolution LCD panels following TDsync guidelines, thus enabling separate display and touch times with resolutions up to WQHD and 120Hz touch sensing. This in turn enables a faster response and a great touch experience.

While many touchscreen designs employ at least some means of display-noise mitigation – for example, simultaneous multi-transmitters driving a higher touch transmission voltage, and/or sophisticated waveform analysis algorithms, they often require design trade-offs: such as slower sensing speeds, higher power, and longer development times. TDsync technology takes a unique approach, one that relies on the “rhythm” of clock cycles and takes advantage of the openings in them that occur naturally. Furthermore, Synaptics touch-sensing and display controllers, aided by TDsync, deliver a cohesive, tightly integrated solution that addresses the entire touch and display functions – and the synchronization of them – to optimally mitigate noise issues.

Yes, timing is everything, and Synaptics’ timing is perfect with TDsync.

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