Introduction

Synaptics ChiralMotion™ technology is an alternative to scrolling regions, Virtual Scrolling™, and range-extension coasting features that are designed to enhance scrolling for two-dimensional (2-D) TouchPad and ClearPad input devices.

Traditional scrolling methods—scrollbars, wheels, and scrolling regions—are more restrictive, less efficient, and require fatiguing repetitive motions. ChiralMotion allows long, continuous yet precise, scrolling actions using natural, intuitive finger motions. ChiralMotion is not limited to scrolling; any application that could use a knob or arrows for the user to enter one-dimensional (1-D) input is also ideal for ChiralMotion.

ChiralMotion Components

A ChiralMotion-enabled device consists of three components: a conventional 2-D measurement subsystem (TouchPad or ClearPad), one or more mode selection mechanisms, and the Synaptics Chiral engine.

The absolute position information available from TouchPad and ClearPad sensors allows mode selection to be accomplished by touching down on the sensor at the appropriate location and then making clockwise or counterclockwise circles, eliminating the need for additional mode selection hardware.

The ChiralMotion engine uses complex algorithms to achieve these simple conceptual principles:

• The initial direction of scrolling is developed from initial 2-D linear movement.
• A linear 2-D movement, extended by subsequent 2-D rotation, preserves the direction.
• Scrolling direction is correlated with 2-D rotational direction.

A graphical representation of these rules is shown below. An example of a 2-D movement path is shown in the upper half of the figure and the scrolling action is shown in the lower half. An initial upward-scrolling direction is assigned by initial upward vertical motion (A). Subsequent 2-D rotational motion (B) preserves the scrolling direction. A linear reversal (C) causes a change in scrolling direction, and a rotational reversal (D) causes a second change in direction.

Note that the amount or distance of scrolling is proportional to the magnitude of the 2-D motion. This proportionality takes maximum advantage of the inherent capabilities of a Synaptics 2-D device. To traverse long distances, it is easier to produce a few large rotations rather than many small rotations.