Portable viewer/ebook
One potential use for Juicebox is in conjunction with an E Ink
display. The board is designed to mount to the rear of an E
Ink TFT module and interface via the 30 way FPC
connector. There is also an interface connector spaced further
towards the center of the juicebox board, in case the device
design calls for the controller board to overhang the edge of
the TFT (for instance, in order to have buttons on the front
face of the device, as supported for rev x02). The thickest
part of the board is over the MMC slot, which is 3.7mm. This
is also the height of the li-polymer battery, so including the
E Ink module, the entire component stack up including an
adhesive layer is less than 5mm. If a case is built using say
0.5mm titanium sheet on either side, a device thickness of 6mm
could be acheived. This is about half as thick as a palm
V.
E Ink is a good disply choice for this controller since
juicebox can only scan the display relatively slowly, and
probably can't do any other tasks while scanning the
display. Fortuntately, the E Ink panel only needs scanning
when you want to change the image. This also means that most
of the time the controller and panel can be in sleep mode and
power consumption can be kept at a minimum.
Originally, I thought there might be enough processor
bandwidth to enable keeping the MP3 decoder busy while also
updating the display. Sadly this is not the case, as either
activity almost maxes out the processor. Would be nice to have
something faster in there...
For the Society for Information Display 2003 in Baltimore, I
made the ebook/MP3 player shown below. It should operate for
about 10 hours of display update or MP3 play from the 2
lithium polymer batteries in there.
I made the case entirely out of laser cut acrylic, backprinted
on the front piece with screen printing ink (thanks to JD
Albert for helping out with that!). The front piece is stuck
to the core with 3M 300LSE adhesive, and the back is held on
with 2-56 torx stainless screw driven into laser cut and hand
tapped holes in the core. The full package is 7.5mm thick,
since I used acrylic for the front and back sheets. If
titanium was used it could be thinner, but I sort of like the
way the acrylic looks.
Buttons are membrane switches mounted to the back of the
juicebox PCB, with hand sanded lozenge buttons mounted on
top.
Here is a back view:
And some action shots:
For the show we had it set up with 2 playlists (one for images
and one for MP3s), which were synched up. So hitting the
bottom of the two big buttons would advance to the next
image/MP3, and hitting the other one would go
back.We had a few news releases and dictionary pages, with a
narrator reading them on MP3. Then we had a few that were more
like single frame music videos; just an image to go along with
a song, like a picture of snoop to help you get in the mood
for one of his tracks.
Standalone MP3 player
Another option would be to use an small LCD instead of the E
Ink panel, and to package the components differently. This
would give you a pocket size MP3 player, a bit smaller than a
business card in footprint, and about 9mm thick.
Here are two pictures of what the innards of such a system
might look like, using an Epson LCD from a cell phone:
As part of my development for the ebook above, I also did an
MP3 only case, lasercut out of acrylic and constructed in a
similar way to the ebook case. I have a new case designed with
some graphics on it, but I screwed up the scale somewhere
along the way so when I cut, it was the wrong size. I'll fix
that pretty soon. Anyway, the device is 11.5mm thick with the
acrylic covers. I also had room to mount a 3.5mm stereo jack,
which is way nicer since I have not been able to find a set of
headphones which can do 2.5mm without an adapter. So far we
have track selection, volume control,
playing/pausing/stopping, and song display working for
this.
Others?
My friend Ara and his little brothe want to
hook up a GPS board to the serial terminal and make a GPS
device, maybe with maps or coordinates or something, as well
as some audio messages via canned MP3s. Brian and I have some
other ideas too...
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