VisionClear

Anti-reflection coating

The aim of incorporating anti-reflection technology to the range of BeoVision models currently available is to provide high-quality visual experiences, irrespective of lighting conditions.

Direct reflections caused by lamps and windows are eliminated and the reflection of diffuse light is reduced to a minimum. The result is an improved overall contrast, providing a picture rendition of very high quality even during daylight hours.

Destructive interference

The coating process consists of applying three layers of a solvent-mixture to a large glass panel. Each layer must be applied with an depth accuracy of 3 - 4%, equalling a measure of just 3 - 4 nanometres (3 - 411000 millimetres).

To remove the reflection of a specific colour, a layer at the thickness of exactly 25% of the wavelength needs to be applied. The reflection is then in anti-phase; it is said to 'overlap'.

 

 

Reflections from lamps and windows are drastically reduced by the anti-reflection coating. Also the diffuse light emission of lit-up surfaces such as walls, carpets and floors are reduced, providing a high contrast picture. Anti-reflection coating is therefore especially beneficial also for watching TV during daylight hours.

 

 
A normal un-coated glass surface reflects about 5% of ambient light, sufficient for detailed mirroring of lit-up objects and surfaces

 

Applying anti-reflection coating reduces the amount of reflections by a factor of 10, equalling a total reflection of just over 0,5%. The benefit is a clear picture with improved contrast A triple layer coating is used to widen the range of wavelengths removed, so that the colours most visible to the human eye are eliminated. The only colour which remains as visible reflection is a vague violet tinge.

 

Eliminating wavelengths

Graph showing the effect of the three-layer coating to different colours/ wavelengths. The layers are designed to match the colours most sensitive to the human eye. The majority of visible colours are reduced to a reflection below 5%.

 

 

 

 

 

The amount of light reflected by the coated surface is reduced to 0,6%, compared to the 5,2% for an uncoated glass surface.

Reducing reflections by a factor of 10 drastically reduce the annoyance caused by reflected lamps and windows. However, the most important effect is the improved contrast, as the light from the picture tube does not have to compete with the ambient light in the room.

The anti-reflection coating combined with the contrast screen is especially beneficial when television is viewed by daylight or in illuminated surroundings.
By applying the greyed contrast screen, the light transmitted by the picture tube is reduced by 50%. However, as diffuse light from the surroundings passes through the contrast screen twice, only 25% of the light is reflected. The result is a significantly increased contrast, adding to the effect of the anti-reflection coating.

 

Characteristic links of the video chain

 

 

 

 

 

< Characteristic links of the video chain

Note, that after cleaning an antireflection coated surface, all traces of cleansing agent must be removed entirely, as they in principle would influence the thickness of the coating layers, causing the coating to loose its effect.

Development of VisionClear Processing

The picture quality elements of VisionClear are as follows:

The above are the electrical elements of VisionClear. The last and very important elements are mechanical: the contrast glass and the coatings, improving daylight viewing even further (see further details on Contrast Screen Coatings)

Over the years, Bang & Olufsen has improved on these analogue picture improvement technologies to an advanced level in order to deliver the unsurpassed picture quality of their TV sets of today. Furthermore the technologies are the platform for future picture quality, influenced by digital technologies, and will not be made obsolete by this.

 

 

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