Touch Capabilities - Single, Dual, Multiple, Gesture
An ever expanding variety of touch enabled products are in use today. As touch popularity grows, the reality of what certain terms mean becomes clouded by confusion, myth and legend. Below are some defintions that will assist in understanding what capabilities are associated with the terminology.
Single Touch occurs when a finger or stylus creates a touch event on the surface of a touch sensor or within a touch field so it is detected by the touch controller and the application can determine the X,Y coordinates of the touch event. These technologies typically do not have the ability to detect or resolve more than a single touch point at a time as part of their standard configuration.
Single Touch with Pen
Single Touch with Pen input functionality can range from a simple, inactive pointer or stylus to complex, active tethered pens. Inactive pens enable the same input characteristics as a finger, but with greater pointing accuracy, while sophisticated, active pens can provide more control and uses for the touch system with drawing and palm rejection capabilities, and mouse event capabilities.
Enhancements to firmware, software and hardware by many single touch technologies have increased their touch functionality. Some touch technologies can use advanced processing capabilities to "detect" or recognize that a second touch event is occurring, which is called a "gesture event." Since single touch systems can't resolve the exact location of the second touch event they rely on algorithms to interpret or anticipate the intended gesture event input. Common industry terms for this functionality are two-finger gestures, dual touch, dual control, and gesture touch.
Two Touch refers to a touch system that can detect and resolve two discrete, simultaneous touch events. The best demonstration of Two Touch capability is to draw two parallel lines on the screen at the same time. Two Touch systems can also support gesturing. Note: Certain touch technologies have the capability of emulating two touch by using an API (Application Program Interface) that allows a single touch to program and therefore predict what the next touch might be. For example, a touch on the corner of an image might have several functions built-in, e.g., the next touch will be to squeeze, rotate, etc., and therefore gives the appearance of being a true "two touch" system. This is often referred to as 1.5 touch. This additional programming within the API acts exactly like a GUI or graphical interface between the touch display and the source computer.
Multi-touch refers to a touch system's ability to simultaneously detect and resolve a minimum of 3+ touch points. All 3 or more touches are detected and fully resolved resulting in a dramatically improved touch experience. Multi-touch is considered by many to become a widely-used interface mainly because of the speed, efficiency and intuitiveness of the technology.
Touch Capabilities Comparison by Touch Technology
This table lists popular touch technologies and associates their ability to work with single, dual, multiple and gesture functions.
| Touch Capabilities Comparison by Touch Technology | ||||||||||||
| Touch Technology: | Single Touch: | Single Touch with Pen: | Single Touch with Gesture: | Two Touch: | Multi-Touch: | |||||||
| Infra-Red (IR) | yes | special stylus | with upgrade | yes | no | |||||||
| Resistive | yes | any stylus | with upgrade | no | no | |||||||
| Surface Capacitive | yes | active stylus | with upgrade | no | no | |||||||
| Optical (Camera) | yes | special stylus | with upgrade | yes | yes 1 | |||||||
| Surface Acoustic Wave (SAW) | yes | special stylus | with upgrade | no | no | |||||||
| Bending Wave (3MTM DST) | yes | any stylus | with upgrade | no | no | |||||||
| Projected Capacitive | yes | special stylus | standard | yes 2 | yes | |||||||
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