touchscreenmagazine.nl alles wat u wilt weten over touchscreens

Optical Imaging

A relatively-modern development in touch screen technology, two or more optical sensors are placed around the edges (mostly the corners) of the screen. Infrared backlights are placed in the sensor's field of view on the other sides of the screen to project a uniform field of infrared light slightly above the glass surface. A touch shows up as a shadow and each pair of optical sensors can locate the touch or even measure the size of the touching object. This technology is growing in popularity, due to its scalability, versatility, and affordability, especially for larger units.

This technology comes as two, three or four camera solutions, providing dual and multi-touch functionality. Optical imaging is one of the more modern touch technologies and has substantial benefits over earlier technologies:

• This technology uses optical sensors to detect the touch point, the touch registers just before the physical touch on the screen. This means that users can apply zero or light touch to the screen to initiate a response, and any input device, such as a paintbrush, finger, pen, or stylus will work.
• Surface coating overlays are not used on the touch screen surface, which creates a crystal clear image. In addition, scratches on the touch surface will not affect the touch screen operation.
• Optical imaging scales to very large displays (120 inches), making it possible to create genuinely collaborative, interactive conference and teaching settings.
• Optical imaging provides a solution without calibration drift. Once the touch screen has been calibrated it does not require any further adjustment. This means virtually zero maintenance costs.

Advantages

• Technique scales to very large displays
• Functions with scratches and surface wear
• Touch activated by bare finger, gloved finger, or stylus
• Transmission is typically >90%

Disadvantages

• Moving liquids or solid contaminants may cause false touches or non-function until completely removed
• Requires a bezel design to house the edge positioned camera system
• System thickness is typically 3.5 mm in addition to the thickness of the glass
• Touch occurs slightly above the actual surface
• Limited to 2 resolvable points with 2 cameras; 3 or more resolvable points with 4 cameras

Touch functionality

• Single touch
• Dual touch
• Multi-touch

Product types

• Overlay frame
• Display solution

Applied in:

NWTF-40 monitor