Pixel Qi Technology Explained.
By Best-eReaders, March 14, 2010
As chief technology officer of One Laptop Per Child (OLPC), Mary Lou Jepsen has an extensive experience in making low-power and cheap displays. Jepsen’s company, Pixel Qi, is redesigning the concept behind LCD to produce a low-power colored display for portable devices. Rather than starting a completely new technology, what Jepsen and her team did is to add special layers to the screen in order to improve it.
Once dismissed by critics as vaporware, the Pixel Qi display got everyone talking at the 2010 CES display in January.
Bridging the Gap Between LCDs and EPDs
The Pixel Qi display can be a color LCD screen one moment, then an eReader-like B/W display the next upon command. It marries the color saturation and page-turning speed of LCDs with sunlight readability and power efficiency of EPDs.
3 Modes of Reading
Pixel Qi operates on 3 modes, allowing you to switch from a color setting to a B/W reflective setting depending on your reading needs:
1. Transmissive Mode
In transmissive mode, Pixel Qi display works just like full-color, traditional LCD screens.
It contains millions of pixels, which are divided into green, blue, and red sub-pixels. Light emanating from the back of the device is used to control the behavior of the sub-pixels, while polarizers on the panel controls the amount of light needed to create the right combination of sub-pixels.
Pixel Qi’s screen display has a pixel resolution of 1024 x 600.
What differentiates Pixel Qi display from conventional LCDS is that this transmissive mode can be turned off. By pressing Fn + F2 ( as shown during the demo), the screen can switch to a black and white mode similar to ePaper displays.
2. Reflective Mode
The Pixel Qi display is engineered in such a way that it mimics the workings and feel of EPDs. In the reflective mode, the back light is turned off. There’s a layer of mirror embedded on the display that reflects back the ambient light that hits it. In the process, shades of gray are produced. In the reflective mode, the Pixel Qi display mimics the looks and feel of EPD displays.
Unlike EPDs, however, Pixel Qi display continues to burn power, refreshing at the rate of 60 Hz per second so it can’t provide the same week-long staying power of EPDs.
It has one big advantage over LCDs, though. Unlike your devices with LCD screens, you can bring your Pixel Qi to the beach or to the park by turning on the device’s transflective mode.
3. Transflective Mode
In transflective mode, Pixel Qi display’s special layer over the display transmits part of the light it receives and reflects part of it. This special layer allows users to see what’s being displayed on the LCD-like screen even under direct sunlight.
In a nutshell, here are the advantages that Pixel Qi offers over traditional LCDs:
- Readability under direct sunlight
- Lower power consumption
- Fully saturated color
- Lower cost because it can be made using existing LCD processes and tools
- In reflective, power savings mode, it “consumes 25 % to 50% less power than regular notebook screens.
Its advantages over EPDs include:
- Faster refresh rate
- Color
- More versatile display
May Lou Jepsen announced that the Pixel Qi displays are already in production and will go into mainstream in 2010.
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