Pico projector hardware + controls


Could you, please, let me know how the pico projector works
internally, i.e. are the individual pixels set in a sequence (similar
to CCD) and then "displayed" at once, or are they set up all in
parallel and the displaying is immediate, or do they work in a
sequence and high frame rate makes sure that our eyes perceive in as a
nice stable image?

Where could I find more information on this matter? Are detailed
timing diagrams available somewhere?

Many thanks!

The TI micro-mirror device is basically a CMOS static RAM chip, with a
layer of mirrors about 11 um wide
built on top of the RAM structure. Store a 1 in that memory cell and
its mirror flips to the left. Store a zero and
the mirror flips to the right. It has an array of mirrors equal to
the number of pixels on the entire screen.

So, all pixels are displayed at once, and they are pulse-width
modulated to give gradations of brightness.
An intense light is focused on the array at a slight angle, and a
projection lens focuses that image onto a screen.
Now, it gets more complicated to do color. The high-end DLP
projectors use dichroic mirrors to split light into
3 wavelength bands, and then runs that color-separated light into 3
separate MMD chips, and then recombines
the images with beam splitters for projecting through a single lens.

The lower cost projectors use a rotating color filter that lights the
array with one color at a time, and the logic brings
up the correct mirror pattern for that color. The colors change at
least 60 - 100 times a second, so you don't see
them flickering.

The Pico projector uses 3 high-brightness LEDs, that I assume blink in
sequence to light the MMD with each color.

TI is quite cagey about the technical details of the MMD chips. I
can't understand why, as they have been granted
an amazingly broad patent for this technology. I had an application
for a photoplotter back when this was new technology,
and they absolutely would not talk to me, I was too small for them to
take interest. You can get development kits that
are basically a complete, working projector plus all technical
documents. When I last looked (a LONG time ago)
these ran around $7000.


Could you, please, let me know how the pico projector works
internally, i.e. are the individual pixels set in a sequence (similar

You can get more info in the PDF manuals found in these pages:


Its actual resolution is half-vga 320x480 (refresh is up to 60.3 Hz); a 640x480 input signal gets scaled to that resolution. In the "Pico kit programmer's guide" you can find its I2C commands, such as screen flipping, LEDs duty cycle, degamma/AGC control, splashscreen, 50/60Hz/ext select, and so on.