Archived from groups: comp.sys.laptops,comp.sys.misc (
More info?)
Just finished designing some luggable prototypes, so timely...
It's Make or Buy...
o Customised v off-the-shelf v hybrid.
That is a function of 2 areas...
o Application mix
---- Photoshop = good display + good CPU + multi-GB of RAM
-------- bigger your dataset (images) the more RAM needed
-------- ideally a 3.5" HD over 2.5"
---- CAD = good display + comfort is critical
-------- ideally reliability as number one
o Usage mix
---- luggable means portable, but not laptopable
---- so I suspect you mean multi-location with power point
---- I also suspect weight isn't #1 re idea of >=19" TFT
Now, solutions...
Laptop (Off-The-Shelf)
o +ve
---- Capable = 17" screen + 7200rpm 2.5" HD + as many GB as possible
---- UPS integral = true mobile usage, compact, relatively light (<12lb)
o -ve
---- Single point of failure = Expensive repair
---- Higher ownership cost = Lose more sunk cost when you u/g
Micro-PC + TFT (Off-The-Shelf)
o +ve
---- Powerful = Pentium-M CPU possible in 250x150x65mm box (StealthComputer)
---- Lightweight = 20-25lbs for Micro-PC & TFT, compact
o -ve
---- UPS possible only if external battery source
---- Limited u/g path = very proprietary box/mb/system (basically industrial SBC)
Shuttle + TFT (Off-The-Shelf)
o +ve
---- Powerful = Desktop CPUs + 10,000rpm 3.5" HD + multi-GB
---- Easily upgraded & repaired = easy desktop parts, cheap repair & easy u/g
o -ve
---- Weight = around 28-35lb for Shuttle & TFT
---- No UPS = power off means data-lost
---- Limited form-factor = no dual-CPU, semi-proprietary u/g path
---- Big box even tho it is a Shuttle
Micro/Shuttle-PC + Luggable-TFT/Keyboard (part customised)
o +ve
---- PC part is off the shelf
---- TFT/Keyboard a) linked or b) simply custom carry-case
o -ve
---- designing a TFT/keyboard enclosure isn't easy
True Luggable (DIY Customised)
o +ve
---- Powerful Desktop & TFT with a handle on it
---- Rugged if you wish, multi-SCSI RAID, dual-CPU, 22"-TFT
o -ve
---- you design it, you build the enclosure, you fit it, you fix it
---- requires CAD or wooden mockup capability
To make the choice, needs some consideration of the other options.
TFT monitors are not portable:
o Weight as a luggable or inn a case is an issue with a TFT monitor
---- 17" TFT laptop = 12lbs
---- 17" TFT monitor = 18-22lbs
o Considering a 19-22" TFT this rises further
---- so transportable, or luggable in the true sense is the reality
TFT monitors are not rugged, or compact:
o TFT Laptop has a screen about 12-15mm deep
---- friction hinges at base, invertor & signal convertor in base
---- sometimes invertor behind the screen, or at the base
o TFT monitor has a screen which peaks at 50mm deep
---- edge-thickness is often not the maximum depth
TFT monitor construction:
o TFT monitors use a laptop-thin glass TFT panel
---- metal contacts are directly onto glass
o TFT-panel is fitted to a pressed-steel frame (heavy) for stiffness
---- the glass is relatively weak
---- laptops use edge-on flat-bar to give bending stiffening
---- laptops are bad 1-sided bending (close in middle or 2 hands)
o Invertor-Board & Signal-Convertor sit on the back
---- hence the typical 1.25" / 35-38mm minimum thickness
o ABS case sits on the front & rear
---- that pressed-steel frame screws to the ABS front
---- the ABS rear screws to the front & has the VESA mount
TFT monitor fixing:
o Small monitors use VESA plate - 4 holes set 75x75mm or 100x100mm
---- plate fixes to the ABS monitor rear, not the TFT steel structure
o Large monitors use custom plates & more bracing
---- which disproportionately increases their weight re more steel
So check the "packaging" of the TFT monitor from factory specs.
o You either have the invertor/signal board behind the TFT
---- so contribute to depth, but not L+W dimensions
o Or you have the invertor/signal board beside the TFT
---- so do contribute to L+W dimensions, but not to depth
The other factor here is the TFT monitor PSU:
o Externalising the PSU makes it thinner - or you need a mains feed
o Externalising the PSU often means 12V brick - powered from the PC PSU
So...
o Transporting the TFT in a case needs protection
---- simple custom flight-case from any maker
---- ideally 5mm alloy double-angle, edging & 5mm ABS/PP
---- go see www.penn-fabrication.com under "hardware" section
o Luggablising a TFT with a PC in a case needs protection
---- same applies - only you are joining the two
Tilting a TFT...
o A true luggable is PC+TFT bolted together
---- typically the combined intentity tilt via tiltable feet
---- those tiltable feet are not off-the-shelf (custom)
o Making true luggable with tilting TFT is difficult
---- hinge TFT at base = huge friction hinges re sheer weight
-------- laptop TFT hinges are countering 1/2 Mass @ C-o-F x distance
-------- desktop TFT hinged at the base has a vastly higher mass
---- hinge TFT at middle = tiny friction hinges re positioning
-------- but increases luggable enclosure depth re tilt space
Tilting a TFT-Keyboard combo
o If you are thinking of housing just a TFT & keyboard, hold
o It would make a semi-laptop scenario, with a power-box elsewhere
o Unfortunately it is a heavy solution - unless you rehouse the TFT
o Rehousing desktop TFTs isn't so easy
---- depth is near fixed -- re invertor/signal-board position/cables
---- weight is near fixed -- re requisite steel frame integrated in
---- you can't just stick it in a sorbothane sock sway-space
o Laptop TFTs are LVDS - so power & signal are combined
---- desktop are still 2 cable - and far higher backlight power (25W+)
With those provisos, creating a true luggable:
o Enclosure
---- Flight case h/w - double-angle extrusion, edging hybrid, latches, corners
-------- www.penn-fabrication.com under Hardware
-------- you want 5mm parts, using 5mm PolyPropylene or ABS re weight/strength
o Ruggedise
---- Simplest is shock-mounts - commercial off-the-shelf stud-mounts
-------- www.macmaster-carr.com do anti-vibration grommets to shock mounts
-------- "anti vibration solutions" under google is another company (big selection)
---- Complex is Sorbothane goo - sheets creating custom mounts, or stud mounts
-------- this is a high-CAD, high effort solution
---- Cheapest is 1" of Polyethylene foam around a frame
-------- or ConFor foam, an E-A-R shock absorbing foam - www.macmaster-carr.com
-------- you do not use off-the-shelf polyurethane foam which rebounds 40G into 70G+
---- Need is re 1) TFT glass 2) re CPU heatsink mass on high G coming off the m/b
o PC & TFT mount
---- PC - either vertical m/b tray & another tray for 1U PSU & HDs
-------- or alloy PC skeleton re-used if you want more than 1 card (1U riser)
---- TFT - posts to another plate to mount the TFT on
-------- no tilting capability, just hardmount
o Foam surround
---- don't cover the TFT vents, but closes the design re airflow
---- side-port the airflow thro the chassis
---- use panel mount & flying tails to internal connectors ideally
-------- Bulgin do panel mount ruggedised USB & RJ45 in pass-thro, and Power
-------- no-one does ruggedised (sealed) RJ11 so the military aren't on 56k
o Keyboard loose in front of case
---- IBM USB Travel Keyboard -- touchpad & trackpoint in 22mm laptop style keyboard
-------- great for loose keyboard, hard to build into a design re shape/design
---- Cherry G84 Trackball Keyboard -- trackball in 22mm laptop style keyboard
-------- easy to build into a design - commonly chosen for 1U TFT/Keyboard units
o Tilting feet
---- because making the TFT tiltable is not easy
-------- re size of friction hinges needed (bottom/top mounted hinges)
-------- or re space taken up by friction hinges (mid mounted hinges)
-------- or re stabilising the TFT in transit (re TFT slapping around)
---- look around other commercial designs here, adapt, improve, innovate
Look up BSI Computer & Dolch and others for ideas.
Luggable allows:
o 22"-TFT Dual-CPU, multi 3.5" drive (SCSI, 10k-rpm SATA), Multi-GB, 1U PSU
o 10.4"-TFT, Mini-ITX P-M, 12V supply that is light yet rugged
So a luggable for some users has benefits over a laptop.
Overall, you need to:
o Carefully ID the usage - re actual application
o Carefully ID the potential solutions - re laptop to shuttle to luggable
o Cost out those potential solutions - re now & lifecycle cost
In many ways a Luggable is just a "Panel PC" - like a Mac/TFT combo.
However you can go far beyond that and create something truly luggable,
do it right and it will last a very long time - easily upgraded.
Note if you go redundant PSUs it will rocket the weight up, not that a
22"-TFT on a luggable is probably immovable - most stop at 17", 19" maybe.
Luggables use LVDS displays rehoused as a rule - ConFor foam gasket around
them (EAR have a whitepaper on that design) or Sorbothane/Poron Gel stuff.
ConFor foam is very good - F1/Indy crash use, but goes like concrete at a
low temperature environment, so do consider that. Military, Big Business &
many others now use luggables increasingly - 200M market is now 7B.
Frankly, the simplest for a power-luggable is this:
o Lightweight portable PC
---- Shuttle, StealthComputer, that sort of thing
o TFT in a custom flight case
---- keyboard pocket, TFT sits in a foam lined case you just buy-in
Going for tiny portable PCs moves you into proprietary - so you end up in
the laptop TCO & single-point-failure area with less options & features. The
key sticking point re weight/portability will be the sheer weight/size of TFT.
Whilst you can find laptops with 1400+ resolution in 15", in TFT monitors or
LVDS panels (which need an interface to desktop boards) it is just unavailable.
--
Dorothy Bradbury
www.dorothybradbury.co.uk for quiet Panaflo fans
/www.polywell.com/us/desktop/qboxNF3B.asp, and a
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