to the maximum achievable levels, drastically increasing the perceived contrast ratio, increasing the dynamic range, improving the viewing angle dependency of the LCD and drastically reducing power consumption. The combination of LED dynamic backlight control in combination with reflective polarizers and prismatic films (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman make these "LED" (LCD) televisions far more efficient than the previous CRT-based sets, leading to a worldwide energy saving of 600 TWh in 2017, equal to 10% of the electricity consumption of all households worldwide, or twice the energy production of all solar cells in the world. The prismatic and reflective polarization films are generally achieved using so called DBEF films manufactured and supplied by 3M. These reflective polarization films using uniaxial oriented polymerized liquid crystals (birefringent polymers or birefringent glue) were invented in 1989 by Philips researchers Dirk Broer, Adrianus de Vaan and Joerg Brambring. A first dynamic "local dimming" LED backlight was public demonstrated by BrightSide Technologies in 2003, and later commercially introduced for professional markets (such as video post-production). Edge LED lighting was first introduced by Sony in September 2008 on the BRAVIA KLV-40ZX1M (known as the ZX1 in Europe). Edge-LED lighting for LCDs allows thinner housing; the Sony BRAVIA KLV-40ZX1M is 1 cm thick, and others are also extremely thin. LED-backlit LCDs have longer life and better energy efficiency than plasma and CCFL LCD TVs. Unlike CCFL backlights, LEDs use no mercury, an environmental pollutant, in their manufacture. However, other elements (such as gallium and arsenic) are used in the manufacture of the LED emitters; there is debate over whether they are a better long-term solution to the problem of screen disposal. Because LEDs can be switched on and off more quickly than CCFLs and can offer a higher light output, it is theoretically possible to offer very high contrast ratios. They can produce deep blacks (LEDs off) and high brightness (LEDs on). However, measurements made from pure-black and pure-white outputs are complicated by edge-LED lighting not allowing these outputs to be reproduced simultaneously on screen. Full-array mini-LED backlights, consisting of several thousand WLEDs, were being researched for TVs and mobile devices in 2017. The white LEDs in LED backlights may use special silicate phosphors, which are brighter but degrade faster. The size of the LEDs is one of the factors that determines the size of the bezel of LED-backlit LCDs. Quantum dot