3M Touch Systems

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Touch Screen Optics Training

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3M Touch Systems

© 3M 2007. All Rights Reserved 3M CONFIDENTIAL

Glass SurfaceThe glass surface itself can be textured, adding raised “features” to create troughs and peaks to diffuse reflections. This reduces gloss, and if engineered properly, can minimize the effects of haze, clarity, and sparkle.

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3M Touch Systems

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Light Transmission Total Light Transmission

A certain amount of that incident light will be absorbed by the material A certain amount will be reflected off the material The rest of the light passes through the material and is known as the total transmittance

AR coatings can increase the amount of transmittance by adding antireflection

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3M Touch Systems

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Light Transmission

•Light is Transmitted, absorbed, & reflected•Soda-Lime glass has a refraction index of 1.5•Transmission through glass alone is down to 92-94%

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3M Touch Systems

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Haze• Haze is the % of light scattered > 2.5° from the incident beam • The lower the number, the better the quality of the image• Touch screens range in haze values from 1%-10% depending on materials used and surface finishes.• Haze is not affected by the distance between the touch screen and display.

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3M Touch Systems

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Clarity• Loss of clarity occurs when the incident light is scattered at a narrow angle < 2.5° from the incident beam with high concentration. AKA Narrow Angle Scattering, causes poor see-through quality, making it difficult to see the fine details ofthe projected image.• The higher the clarity value, the better the quality of the image.• Clarity worsens with increased distance between the touch screen and display.

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3M Touch Systems

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Sparkle High sparkle is best described as a perceived graininess to the screen, where each

grain takes on a certain color and seems to shift as you adjust your viewing angle Sparkle is cause by several factors

the relative size of the display pixel size to the size of the features within the coating the distance from the display to the touch screen, and the index of refraction dispersive nature of the coating

Coatings on the surface of the touch screen, such as an anti-glare coating, can have a significant impact on the amount of sparkle displayed by a touch screen.