Re: Speedometer - transparent first-surface reflector needed!

["Dave Zug" <dzug@delanet.com>]

I'm not sure if this helps, but in 89 and 90, the first HUDs went on the
Grand prixs as an option, and on turbo GP's standard. the glass on the turbo
GP was this special type I guess cause it costs $700 to replace today. a
sticker comes on it "polished for HUD"...

I know on the later cars equipped with HUD there is a PATCH of glass where
the HUD shines, insted of the whole windshield being polished. maybe the
early windshield was only ploished and this one had the special material...

anyway, my third source may be only in my head, I thought I saw a sticker
like thing on the windshields of a 95 or so grand prix.  maybe they thought
it was good nuff, maybe its more correct than what you are talking about.


I started a project to take the ALDL and push a certain byte to a pair of
7-seg LCD's for a gerry-rig HUD. It was for the buick GN.. I had the stream
reading accurately - needed to keep going but the car started shaking and
spewing black smoke and I had to dump it on some sucker......  JUST KIDDING
BRUCE!  get up off the floor now ;-))     .

Last I'll say, on the subject of cool instrumentation, I once saw a triple
guage LCD setup specifically for automotive use on a website. the first
guage was 360 degrees around, the other 2 were 150 degrees or something. the
LCD came with drivers for uP use. I thought that was cool. I'm sorry I dont
have info on its maker. It was a flat panel about 3" by 5". I dont think it
was masked, I think it was totally pixel graphical.

thats 4 posts for me, another friday night ;-(

----- Original Message -----
From: mike mager <mikemager@hotmail.com>
To: <gmecm@diy-efi.org>
Cc: <fanglers@xephic.dynip.com>
Sent: Friday, February 25, 2000 5:03 PM
Subject: Re: Speedometer - transparent first-surface reflector needed!


> cwagner asked the GM ECM list: (gmecm@diy-efi.org)
>
> >Does any one have any good ideas on making a digital
> >speedometer, preferably one that can be mounted in a heads-up
> >situation?  More gadgets to fight with, but they are fun.
>
> Alright!  I've got to 'grab' this one!
>
> I am a guy that is completely fascinated by all types of instrumentation.
> In 1972, or so, back in high school, I was completely awed by a Detroit
> concept vehicle with full digital read-out instrumentation (probably
filled
> the trunk with electronics?).  That was the beginning . . .
>
> I went on, by 1978, to learn how to build such instruments myself, using
> 'discrete' MSI ICs (very bulky, un-calibratable, unreliable,
> power-consuming, heat-generating and temperature-sensitive, and just
> generally bad).  I almost figured out MCUs and CPUs in 1981, but it was so
> exotic and expensive, that it took me a few years to get back to it, and
> then it was, "Oh, yeah, I see how it works, that's easy!".  Now I think
> nothing of buying PIC in the UV EPROM package, doing a small bit of
assembly
> language coding, a small bit of hardware, and having a working circuit.
> Digikey works wonders.
>
> I have built a fairly complex instrument system for automotive use, and it
> certainly is no big deal.  I am successfully procrastinating the
(absolutely
> necessary with this level of complexity) systems analysis for a very
> complete, complex, complicated, and worse system (but I think of it
often).
>
> Somebody else may have already been done answering by now, but . . .
>
> I like to say "head-up display", because I only have one head, but most
> others refuse!  I did build a head-up display for my speedometer a few
years
> ago, and I found a (known) problem:
> I had my development board loose on the top of the instrument panel, and
one
> night I noticed a reflection of the three ~1" green seven-segment LEDs in
> the windshield - wow, HUD!;  I went in, connected a one-bit input switch,
> and changed the code to read it, and to select my original seven-segment
> bitmap, or to select a mirror-image bit-map - you may have seen this done
on
> the police RADAR displays, to be readable in the rear-view mirror.  There
in
> a short time, I found the problem.
>
> The problem was that the windshield has (at least) four reflective
surfaces
> (think of a first-surface mirror for LASER vs. a regular mirror, and add
> laminations), and I got way too many reflections - but it did 'work'.  A
> 'real' HUD uses a transparent first-surface 'reflector' adhered to the
> windshield - now, where can we get one?  I see that like the 1992 or so
> Nissan 240 SX had HUD, with that proper reflector, and that they are now
(I
> believe) out of production;  I was told that they were too expensive
because
> of the 'special' windshield, so, that is not a source of a separate
> reflector.
>
> Please give more specific details, if you have any (I could hardly stand
> another project, but . . . ), and maybe we can each build one.
>
> We need to find a transparent first-surface reflector!
>
> Mike
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