Game-Changing Displaytech FLCOS Microdisplay Technology

Micron’s Displaytech family of microdisplays provides full 24-bit color images at 60 frames per second and resolutions as high as SVGA (800 x 600). These reflective microdisplays manipulate light using an incredibly fast type of liquid crystal technology.

And because they’re built on a CMOS process, the display panel, image processing, memory, and LED controllers are integrated on a single chip.

In addition to their diminutive size, these displays draw less than 100mW of power—making them perfect for mobile applications like camera viewfinders, heads-up displays, and miniature projectors for cell phones and handhelds. Our Displaytech microdisplay products also offer the most compelling combination of clarity, brightness, and color fidelity for this market. All of this advanced functionality is the result of several key patents in fields ranging from liquid crystal chemistry to pixel size. Read on to learn more about the ferroelectric liquid crystal on silicon (FLCOS) technology that makes the speed and image clarity of our Displaytech product line possible.

About Microdisplay Technology

Microdisplays are currently developed based on a handful of competing technologies, including liquid crystal on silicon (LCOS) and micromirror. However, each of these technologies requires design compromises among operating temperature, image quality, power efficiency, system cost, and board footprint. The unique attributes of our FLCOS technology, on the other hand, provide a balance of great image quality and power efficiency in a small, integrated solution. While FLCOS has some technical similarities to traditional LCOS, ferroelectric technology’s high speed puts it in another category altogether. To understand why, it helps to know a little about how different technologies display color.

Spatial Color

Most displays, like LCD monitors and televisions, use a technique called spatial color to create the spectrum of colors you see. Each pixel is actually created by three closely grouped red, green, and blue subpixels that are continuously illuminated by a white light source (see the image at left for an example of an RGB pixel array). Because these pixels are so closely grouped, the human eye blends the three shades to interpret a single color for each pixel.

This color design wastes power, resolution, and light, making it a poor option for mobile displays. Because each final pixel is built from three individual RGB pixels, the display must have three times the actual final resolution. It also squanders much of the light through color filters and dark subpixels. For example, a pure red display blocks at least 66% of the total light output because the blue and green pixels are completely black. Blocked light makes the display darker and wastes power—a critical commodity for battery-powered devices.

Sequential Color

Imagine a system that could switch frames so quickly that it could mix the red, green, and blue pixels over time, instead of space, to make a single color—much like a set of still images shown in quick succession fools the eye into seeing motion. This type of sequential color system would provide a full color pixel and increase image quality and color fidelity. But the light flow through each pixel must be controlled precisely and incredibly quickly—which is where our FLCOS technology shines.

Speed – How FLCOS is Different

The "F" in FLCOS stands for Ferroelectric—a description of how the liquid crystal is chemically organized and activated—but the "F" might as well stand for Fast. The details of our patents in liquid crystal engineering are well documented, but simply put, the physical differences of our FLCOS technology allow it to switch the liquid crystal pixels on and off much faster than typical LCOS displays—as much as 100 times faster, at a switching speed of 1/10,000 of a second.

Running at these speeds enables our Displaytech microdisplays to use field sequential color—a superior imaging technique that eliminates the RGB pixel split. Showing 60 frames per second, each frame has a red, green, and blue subframe that is displayed twice per frame in sequence to create millions of possible colors. To create the image for each subframe, the brightness of any pixel is varied by exposing light through it for different lengths of time (not filtering light, like spatial color LCOS)—256 different exposure options for each pixel (8 bit grayscale per color). This method means that each pixel represents the true color, providing better light output, higher resolution, and more efficient power use, while eliminating the color-saturation-versus-brightness tradeoff inherent in spatial color systems.

The difference FLCOS makes can be seen in the split image at right. The left image, produced using our sequential color panel, is clear and crisp. The right image, produced using a spatial color LCOS panel, shows the light loss and muted color typical of these systems.

Viewfinders to Holograms – Current and Future Applications

Innovations