RGB laser driver squeezes embedded pico projectors into a new class of consumer electronics

Targeted applications include smartphones, portable media players, mobile-computing devices, digital cameras/camcorders, accessory projectors, and digital picture frames.

Pico projectors: The next killer app for portable consumer electronics

Quickly becoming small enough to fit into the tight enclosures of today's smartphones, embedded pico projectors promise to transform the multimedia capabilities of consumer electronics. These miniature projectors enable users to display images and video from their portable devices onto walls and other surfaces, effectively freeing consumers from the constraints of their cramped displays. Given the widespread integration of video capabilities in consumer electronics, a large potential market exists for pico projectors. Indeed, market researcher In-Stat predicts that this market is ready to break out worldwide, with revenue growing to $1.1 billion by 2013.

Traditional Pico-Projector Solutions Cannot Scale to Fit Next-Generation Requirements

Until recently, DLP (digital light processor) and LCoS (liquid crystal on silicon) technologies have been the frontrunners among pico-projector architectures.

An established technology, DLP offers HVGA (480 x 320 pixels) resolution at a mid-tier price point. However, it is the most power-hungry technology-consuming 3.5W at the system level. Higher resolutions require an even larger and more power-hungry projector (i.e., a bigger micromirror device), since DLP uses a separate micromirror for each pixel.

Also a mature technology, LCoS employs LEDs to allow for a relatively low solution cost. It offers VGA (640 x 480 pixels) resolution, with better power consumption (~1W to 1.5W) and a smaller solution size than DLP. Yet, like DLP, LCoS requires a larger footprint (i.e., a bigger panel) for higher resolutions. Driven by the diffuse light of an LED, LCoS projectors have significantly less contrast than laser projectors.

In the long term, this inability to shrink to smaller form factors undermines the suitability of DLP and LCoS technologies for the ever-tinier enclosures of today's consumer electronics.

Laser-Based Pico Projectors Deliver the Best Performance from the Smallest Footprints

Laser-based pico projectors offer clear performance advantages over DLP and LCoS architectures. Laser projectors consume the least amount of power (< 1W for an embedded-projector module) for the largest displays (~100 inches wide), while taking up the least amount of board space. Significantly, laser-based architectures are capable of achieving resolutions up to WXGA or even 1080p with the MAX3600.

Laser-based architectures are more scalable than DLP and LCoS. Laser solutions only require a single or dual MEMS mirror, regardless of resolution. This means that designs can be scaled-in terms of both software and hardware-to higher resolutions without changing the imager. In contrast, DLP and LCoS designs would require a different, larger imager and necessitate a complete redesign.

Moreover, laser-based pico projectors are always in focus so images are always crisp, no matter the surface, be it the inside of eye glass lenses, a windshield, or even the back of a hand. The incumbent technologies (DLP and LCoS) require manual focusing most suitable for flat surfaces.

Yet, as new technology, laser-based projectors have been more costly than DLP and LCoS. One reason for this is that only single-channel drivers for red, green, and blue lasers were available, which increase board area requirements, power consumption, and cost.

Maxim's 3-Channel Laser Driver Enables High-Resolution Pico Projectors to Fit in Smaller Form Factors

The MAX3600 allows pico-projector OEMs to overcome these limitations by integrating three discrete laser drivers into a single 5mm x 5mm chip. This integrated solution consumes 75% less real estate and 30% less power than discrete designs, making it well suited for compact battery-operated devices. OEMs will also benefit from a 25% lower solution cost, not to mention an industry-best resolution of WVGA or SVGA for portable devices.

This device integrates all of the functionality needed to simply interface a digital 10-bit RGB video source to virtually all industry-standard, low-power RGB laser diodes. The MAX3600 is uniquely equipped with three 10-bit RGB DACs, which read video data from the host device's 10-bit RGB bus. These DACs allow system designers to precisely control laser current while generating billions of colors and contrast ratios of 5000:1 and higher. Meanwhile, gain and offset functions along with serial ports and registers make real-world, production image adjustments quick and digitally simple.