It's the Physics

Texas Instruments' recent demonstration of a miniature projector has prompted some questions from readers about how Microvision's PicoP stacks up against TI's DLP-based prototype.

Put simply, Microvision is on the path to embed a small, power-efficient projector inside a cell phone. And unless you radically re-imagine what a state of the art telephone is, Texas Instruments can’t embed its projector because of the inherent properties of the DLP technology.

The problems associated with embedding a DLP-based projector into a phone are due to concerns regarding size, heat and power.

Based upon my experience and research into DLP technology, here's why:

For starters, Microvision’s PicoP is significantly smaller, and more importantly, thinner than Texas Instruments’ DLP-based mini-projector. That’s because Texas Instruments’ micro-mirror array needs a single mirror for EACH pixel, which affects the size and thickness of the device. Microvision only needs one mirror, to represent ANY pixel. So, the smaller TI makes its array, the less resolution there is in its final picture. For Microvision, there’s no such limit.

As an example, TI reports that its new projector prototype has 640 x 240 resolution – or ½ VGA (HVGA). Microvision has been showing prototypes with SVGA (800 x 600) resolution – that gives Microvision an advantage of 312% greater resolution. TI could scale up their DLP-based projector to display a greater pixel count, but their entire device would grow in size too. In a nutshell, TI will have to trade resolution for size.

Further, TI’s micro-mirror array size dictates the size of its projection lens. And TI’s projection lens can’t get much smaller –or shorter— without adding visual artifacts. Microvision’s PicoP doesn’t need a projection lens at all. PicoP has infinite focus. And the single mirror is the projector.

PicoP's infinite focus means that you can shine it on any surface, at varying distances, and the image will be crisp and in focus, without having to adjust a dial. By contrast, the TI device will require you to fine tune the focus of the image every time you move your hand.

There are also vast differences in heat and power. Both companies use laser light sources. But Microvision only turns a laser on to create a single pixel including that color. Then the laser nearly instantly turns back off, saving battery power. Meanwhile, Texas Instruments turns on a laser to illuminate the entire array of mirrors. And if a particular pixel doesn’t need that color, this light becomes heat, and is wasted.

For example, imagine a rainbow of primary colors: One third of the picture elements (pixels) are red, one third are blue, and one third are green. TI's device illuminates the entire array with all three colors, even though only 33% of each color is needed in the final image. Two-thirds of the power used to activate the lasers becomes heat, instead of useful light. And for images with lots of black – like starry nights – the power loss is even greater.

Overall, Microvision’s PicoP is significantly more efficient than Texas Instruments in controlling heat and power consumption. These factors, in combination with Microvision’s significantly smaller size, enable Microvision’s PicoP projector to fit and function inside a conventional mobile phone, using the phone’s internal power supply. With Texas Instruments, you need a much larger phone, with a much bigger power supply. And you may need to add a cooling fan.

In short, Microvision’s PicoP is the only device that today is on a path to be embedded into a sleek and thin mobile phone.