Today's projectors uses lenses because a wide angle DLP or LCD panel would block light reflected from a mirror. However, an LED array on a sweeping arm can display a large image without blocking much light.

The image is formed by a linear OLED array of red, green, and blue LEDs on a spinning arm. This spinning action provides airflow to the array so no additional fan is required for cooling. Light from this image is reflected using a spherical mirror, in a fashion similar to this:

http://www.redferret.net/?p=8295

However, the above device has a huge blind spot in the center due to the hub equipment. For the proposed projector, the spinning hub is placed outside the mirror (which is smaller than the area swept by the spinning arm).

Compared to existing projector technologies, this can be energy efficient and self-cooling. Unlike DLP LED, energy isn't wasted illuminating dark pixels.
-- IJK, Mar 18 2007

MP3 Lightcast http://www.redferret.net/?p=8295
A crude version with only 33 LEDs and a big central blind spot [IJK, Mar 18 2007]

Spinning mirrors laser projector http://heim.ifi.uio.no/haakoh/avr/
[Smurfsahoy, Mar 18 2007]

Beamsplit mirrors laser projector http://elm-chan.org...s/vlp/report_e.html
[Smurfsahoy, Mar 18 2007]

Various projects http://www.hack247....ategory/projectors/
[Smurfsahoy, Mar 18 2007]

Tiny Laser prototypes http://web.media.mi...ook_prototypes.html
[Smurfsahoy, Mar 18 2007]

Not exactly a projector... http://www.streettv.tv/liverpool/
HD resolution video, 1.8metres high, daylight visible. [AbsintheWithoutLeave, Mar 18 2007]

I am adding a number of links possibly showing this to be baked in many ways, depending on exactly what you're getting at. Most of them use lasers, not LEDs, but why not use a laser, seeing as how they have vastly further range, use about the same wattage, and are way cooler?
-- Smurfsahoy, Mar 18 2007


I think the reflector will need to be a shape other than spherical.

would LEDs have the necessary power for a projector?
-- xaviergisz, Mar 18 2007


The reason to use LEDs rather than lasers is cost and simplicity. As far as I know, green and blue lasers aren't cheap and simple enough yet--not for being packaged in a high density linear array of them.

LED brightness is certainly a critical issue. One thing which helps a little is that since the array is one dimensional, you can use rows of thick non-transparent electrodes to the sides of the array to feed it plenty of power and help spread heat. Nevertheless, I imagine this projector competing with other low power projectors, currently using DLP LED.
-- IJK, Mar 18 2007


Blue lasers are indeed a problem... If you could make do with only one of each laser, you could get them in bulk for probably about $350 per three laser unit. Maybe 500 or 600 for the projector on the whole. If you're lucky.

5-10 years from now, you'll be able to get a red green and blue laser all for under 50 bucks total, probably. Red diodes used to cost $200 a pop not too long ago. Now they are about $3.

<shrug>
-- Smurfsahoy, Mar 18 2007



random, halfbakery