LEDs, solid-state lasers fuel new display trends

NORWALK, CT—Technology trends in LEDs and in lasers could combine in the next few years to create of a whole new class of display systems. Such displays will likely offer advantages over existing technologies, changing the competitive landscape in significant ways.

Red, green, and blue LEDs already exist for a range of applications. One of the major trends pushing development here is increasing the brightness of these devices to serve more applications. High-brightness LEDs are already being used in display products like LED signage, but other products are coming too. For example, Sony has already announced a 46-inch LCD-TV that will use LEDs instead of a fluorescent tube as the backlight for the display. Arrays of red, green, and blue LEDs are used to provide much richer color saturation than is possible with fluorescent backlight and colored filters—a visibly perceptible image quality improvement and a key advantage of LED illumination.

Another class of product coming to market is the "pocket projector." Here, the idea is to reduce the size of a typical business projector so that it literally fits in your pocket. The only way to do this is with LED illumination. Several research and commercial firms have already built prototypes and we now expect the first products to reach market in 2005. These pocket projectors will be small, but also have very low lumen output, perhaps 50–100 lumens—well below the typical 1200 to 1500 minimum lumens used in a business projector. As a result, these devices are more suitable for 10–15 inch images instead of the 100 to 200 inch images for business use.

How would you use such a product? Developers envision it being useful in small meeting where two to four people could view the projected display. Since the device will be portable, it might be used to project maps to help navigate in a strange city, or it might be coupled/bundled to a cell phone, digital camera/camcorder or PDA product to show messages, data or photos that are much bigger than would be possible if a direct-view display is used in these devices. How about a product that allows display of video, images or text via a USB memory card for gaming, education or entertainment applications?

Laser technology is also coming that will enable projection systems with benefits over lamp-based systems such as longer lifetime and richer colors. Most system makers want to see laser projection displays that use semiconductor sources, but these are not yet available, so pumped systems to create red, green and blue light are more common today. Laser sources offer advantages in the optical architecture too since they are collimated and nearly point sources of light.

Other markets in large screen entertainment are probably 1–2 years off. But, as with LEDs, many are eyeing the big-screen TV market as the next "killer app." Here, laser-based systems may give LED-based systems a run for their money. But lasers will face other concerns like speckle reduction and eye safety. We have seen some of these laser display prototype systems and have been very impressed with the image quality. The contrast is high, the images very sharp and crisp and the color saturation is unbelievable. In fact, these laser displays can create colors never seen with other display systems—a startling result.