Engineering:Ambilight

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Ambilight, short for "ambient lighting", is a lighting system for televisions developed by Philips.

Ambilight creates light effects around the television that correspond to the video content. Philips claims that a "more immersive viewing experience" can result. Ambilight is a lighting system that actively adjusts both brightness and color based upon picture content. Integrated into the television cabinet, Ambilight technology is aimed to enable the viewer to see more picture detail, contrast and color while eliminating on-screen reflections.

Ambilight technology works by projecting light from the rear of the TV cabinet in a very wide range of colors, shades and intensities. Viewers can choose to have Ambilight follow the color and brightness of the programme content – automatically changing with the colors on the screen – or alternatively the light levels and color can be set to match the interior decor or mood in the room. When the television is not on, the unit becomes a lamp, capable of displaying dynamic light patterns.

Ambilight is a feature invented in 2002 by the Philips ASA lab (a central development lab of Philips Consumer Electronics, also responsible for development of flat TV) and Philips Research, both situated in Eindhoven, the Netherlands. These departments worked in parallel: they started from different starting-points, and ended at comparable technologies. Philips Research investigated the application of LED in the home environment. This development resulted in a lighting system that displayed light according to a program (script) that has to be generated for all displayed video content, and which should be translated to the used lamp configuration. Movie directors could use a script to add special effects. The system was demonstrated using multiple light units, spread over the room. The starting point of the ASA lab was the wish to add (white) light units to the cabinet of the flat TV. These light units, lighting the wall around the TV, had to replace the table lamp often placed on top of the bulky CRT TVs. This development resulted in a TV lighting system (based on RGB LED) that reproduces the color and brightness of the content displayed on the TV screen. The concept does not require light-scripts, and is backwards compatible with existing video content. Introduction of this concept was less complicated because it only affects the TV itself. This concept was selected for the Philips Ambilight TVs that have been launched since 2004.

Versions

Although Ambilight was developed using LED light sources, the first Ambilight TVs (launched in 2004) were equipped with CCFL tubes. The higher brightness of the CCFL tubes was preferred to make the Ambilight more visible in bright shop environments, at the cost of a reduced color gamut. Red, green and blue CCFL tubes were mounted at the backside of the cabinet, first at the left and right side but later also at the top and (for wall-hanging applications) bottom side of the screen, reproducing the average screen color. In later executions of Ambilight, the CCFL tubes were replaced by LEDs (2006), resulting in an Ambilight color gamut that matches the picture color gamut. By splitting the Ambilight area in segments of which the color could be individually adapted to the neighboring screen area, the effect of extrapolating the screen on the wall was further improved. To reduce the dark boundary between display and Ambilight area, the “Aurea” TVs were introduced (2007), in which also the bezel of the screen was lighted by the Ambilight system.

With each new generation of Ambilight products, the size of the Ambilight system has been reduced to match with the constant reducing thickness and bezel width of flat TVs. The algorithm (the program that translates the displayed picture towards the Ambilight colors) is constantly improved to optimize the effect for all situations. In the latest executions it is possible to correct the Ambilight for non-white (tinted) walls behind the TV.

View of Ambilight Spectra 3 (Philips 46PFL9705H)
Ambilight-2.jpg
Ambilight-3.jpg

AmBX is a version of Ambilight designed for PC gaming. Similarly, light effects occur resulting from in-game events and actions.

Patents

The concept of adapting ambient light with a video display already existed, but proposed solutions required a separate channel for the light effects in addition to the video and audio channels. Ambilight uses the video channel itself to generate color and the concepts as well as various methods of calculating the color from the video signal are protected by various patents.

The basic Philips Ambilight patent is EP 1379082, written by Theo Overes of the ASA lab. Other inventors are Aeneas Fletterman (graduate student at ASA lab), and the Philips research team led by Elmo Diederiks and Erwin Meinders, consisting of a diverse mix of experts in psychology, user research, software engineering and theatre lighting. Since this basic patent, Philips filed many other patent applications, covering hard and software of the system.

[1] [2] [3] [4] [5] [6] [7] [8] [9] There are several other patents and patent applications as well, although it is not clear which ones actually cover the Ambilight systems that are being sold.

References

  1. ↑ Method and system for controlling an ambient light and lighting unit. International patent application WO 2004006570 (2004).
  2. ↑ Method and system for controlling an ambient light and lighting unit. International patent application WO 2004006578 (2004).
  3. ↑ AUTOMATIC DISPLAY ADAPTATION TO LIGHTING International patent application WO 2005041568 (2005).
  4. ↑ AMBIENT LIGHT SCRIPT COMMAND ENCODING International patent application WO 2005069640 (2005).
  5. ↑ Flicker-free adaptive thresholding for ambient light derived from video content mapped through unrendered color space . International patent application WO 2004006578 (2005).
  6. ↑ Ambient lighting derived from video content and with broadcast influenced by perceptual rules and user preferences International patent application WO 2006003624 (2006).
  7. ↑ PASSIVE DIFFUSER FRAME SYSTEM FOR AMBIENT LIGHTING USING A VIDEO DISPLAY UNIT AS A LIGHT SOURCE International patent application WO 2006003603 (2006).
  8. ↑ ACTIVE FRAME SYSTEM FOR AMBIENT LIGHTING USING A VIDEO DISPLAY AS A SIGNAL S0URCE International patent application WO 2006003604 (2006).
  9. ↑ DOMINANT COLOR EXTRACTION USING PERCEPTUAL RULES TO PRODUCE AMBIENT LIGHT DERIVED FROM VIDEO CONTENT International patent application WO 2006003600 (2006).

External links




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