3M + Acer = All Day Computing And Then Some


Original image source: Kramer Sharp

Getting to all-day computing is a goal for some laptop brands, but Acer has gone a step beyond: the company has now added more computing power on top of an eight-hour battery life. 3M and Acer jointly announced that the Aspire TimelineX-line of laptops have the same eight-hour battery life of the original Timeline but now have more computing power. The two companies achieved this by enhancing light recycling within the LCD and making it more power efficient.

Acer:

The original Aspire Timeline series was the first to break the 8-hour battery life barrier and the Aspire TimelineX matches that and adds excellent power straight out of the box. With Aspire TimelineX, power and battery life are no longer incompatible.

How did Acer do it? According to the press release:

Specifically, Acer, the world’s No. 2 notebook company, has utilized 3M’s multi-layer optical films in its Aspire TimelineX series. The new notebook series provides an impressive extended battery life of eight hours, as well as superior display performance and an ultra slim form factor.

3M’s multi-layer optical films can increase power savings in notebook displays. The additional brightness budget can be used to extend battery life and/or reduce the weight of the battery.

Let’s take a look at how Acer made its TimelineX laptop more powerful while maintaing an all-day eight-hour battery life. What consumes a lot of energy on our laptops? The results vary depending on the laptop, but in general the CPU and the LCD consume the most. LCDs can consume as much as 40% of total power. With that kind of power consumption more power-efficient LCDs can lead to lots of power savings. What is going on inside the LCD that requires so much power?

The LCD can be divided into two big parts: LCD panel and backlight unit (BLU). The BLU is where light is generated. The LCD panel is where light is turned into tiny pixels that in turn work together to form text and images. Improvements are needed both in the LCD panel and the BLU to make the entire LCD more power efficient. I’ll be focusing on the BLU.

The term used to measure light is candelas per square meter. You might have seen something like 300 cd/m2 as part of a LCD monitor’s technical specifications. In display industry jargon its simply called nits. By using a whole bunch of specialized optical films light generated from the BLU is guided toward the front of the LCD.

A typical LCD monitor has a brightness of around 300 nits. Did you know you’re only seeing 3% of what is generated from the BLU? The BLU generates 10,000 nits! The light that comes through the front of the LCD is just 3% of the light that is generated from the backlight. 97% is gone. What’s going on?

Light gets absorbed, scattered, and lost.

Light gets absorbed by many components in the LCD. The bottom polarizer layer, there are two, absorbs 50% of the light that it receives. And the color filter absorbs 70%. Many more layers consume almost all the rest: Indium-Tin-Oxide (ITO), Thin-Film-Transistor (TFT), liquid crystal (LC), etc. Light is also scattered at different angles away from the front of the LCD and eventually lost. The key is to reduce light absorption, guide the light toward the front of the LCD by minimizing scattering, and reduce light lost.

There are many components in the BLU that work to minimize light loss: prism film, lamp cavity reflector, diffuser, reflective polarizer, and brightness enhancement film (BEF), etc. All of these components are important, but I will focus on a special kind of BEF: double brightness enhancement film or DBEF.

DBEF is the key component that recycles light. When light from the BLU hits the lower polarizer only about 50% of light passes through and the other half is absorbed. A DBEF lets about 85% of the light through but almost all of the other non-polarized light is reflected back to the BLU. That light is then passed back through the DBEF again with about half bouncing back. This repeats until all light is passed through or absorbed. The DBEF passes more light through the lower polarizer and that results in a brighter LCD.

With a more efficient LCD using DBEF a LCD product manager can do one of many things. One option is to leave the LCD alone. By keeping all of the other components the same, the addition of a DBEF makes the LCD brighter. Another option is to make use of a DBEF and lower the amount of light coming out of the BLU. This option keeps the level of brightness the same, but will save energy and allow the LCD to consume less power. With the power savings other laptop components can be enhanced, which is exactly what Acer decided to do with its TimelineX. If accurate colors are important a better color filter can be used resulting in deeper colors but maintaining the same level of brightness.

Laptop battery life can be made to last longer by improving the LCD and that can be done by recycling light in the backlight. Once you get to all-day computing additional power savings through better light recycling in the BLU bring options to improve other system components. 3M’s DBEF improved the LCD and made it more power efficient giving Acer engineers room to improve computing power on its TimelineX laptops while maintaining an all-day eight-hour battery life.