Adjustment of Philips ambilight bias illumination
In home cinema and video editing technology, bias lighting is a weak light source on the backside of a screen or monitor that illuminates the wall or surface behind and just around the display.
The purpose of bias lighting is to reduce the perceived brightness of the display as a result of the contrast with the slightly illuminated area around it. This reduces the eye strain and fatigue that occurs when viewing a bright display against a very dark background for an extended time, and increases the perceived blackness and contrast of the display.
Philips ambilight uses this special monitor technology and the RGB LED based bias lighting must be calibrated during production of the TV. This is done with specbos 1211L, integrated into the production system. The device measures the xyY values of the three primaries and based on that a matrix will be calculated to be used by the LED driver. Finally the resulting white spectrum will be checked by another measurement.
This content depending LED backwards illumination allows a more relaxed TV consumption.
The main points of the specification of specbos 1211L for this application are
- Measuring speed (max. 0.5 s per measurement)
- Small dimensions for integration into production
- Continuous and robust operation
- No electromagnetic interference (special EMC test was done)
- 100 % reliable interface (RS 232)