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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: LCD (large -- TV-ish) monitors with SOLID front surface?
Date: Sat, 15 Jun 2024 17:37:44 -0700
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On 6/15/2024 4:22 PM, Jasen Betts wrote:
> On 2024-06-14, Don Y <blockedofcourse@foo.invalid> wrote:
> 
>> The front polarizer of a typical LCD TV ("really big monitor") tends to
>> be flimsy.  A thin piece of glass/lexan might work in that it could
>> distribute the forces over a larger area -- providing "localized stiffness"
>> instead of OVERALL stiffness.
>>
>> Imagine yourself writing on a whiteboard; your motions tend not to be
>> delicate and deliberate but, rather, sharp and erratic.  I need to protect
>> the LCD display from your "abuse".
>>
>> At the same time, ensuring that the protective layer doesn't end up scratched
>> and cloudy from repeated "markings".
>>
>>> If it was stiffer than the display glass you'd need to disassemble the
>>> display to install the protector. (if wanting to mount it using adhesive)
>>>
>>> Or else live with a gap between the display and the protector (increasing
>>> parallax and potentially collecting debris)
>>
>> The parallax is disturbing.  Your "ink" appears *in* the display but your
>> "writing actions" occur outside the protective layer.  So, if there's a
>> schematic, program listing, photoplot, etc. being displayed on ("in")
>> the display, it requires a bit more effort to make your marks where you
>> want them, relative to what is already being displayed (and *updated* to
>> include your marks).
> 
> Have you switched fron non-visible ink to virtual ink?  Do you
> actually want a touch sensing screen?

The pen that you *hold* has NO ink in it (hence "invisible ink").
I.e., I can scribble on the (current plasma) screen for hours and
you would never know where I had scribbled.

But, the pen *creates* "virtual ink" that appears in the video
signal displayed on ("in") the display.

If you start by displaying a white field, then a casual observer
thinks he is watching a person scribbling on a real whiteboard
(and wondering how the "market pen" keeps changing colors to suit
the wishes of the writer).

A *touch* screen would be nice but would complicate things in
that getting more than one (50-90 inch diagonal) would be costly.
My approach allows me to use a screen wherever I happen to be
(though this has had to be plasma, to date, due to the ruggedness
constraint)

A sheet of glass/lexan would actually be ideal as I could arrange
to have one of suitable size wherever I happened to be (to fit
whatever TV was available)!

>> If you think of a TV weatherperson interacting with a green-screen,
>> you can get a sense of how that sort of awkward interface affects
>> the precision of their annotations (anything "exact" is done off-line
>> where it can be revised over time; live updates tend to be really crude,
>> by comparison).
> 
> These days they use actual displays instead of chromakey. Sometimes
> even touch sensing displays; there's funny videos of the presenters
> discovering this:  eg. https://www.youtube.com/watch?v=0Goz0PnhEg8

They are still green (or blue)-screens, here (local).  The presenter is
always looking off to (e.g.) stage left to see the composite signal that
is being broadcast (i.e., with HIM/HER *in* it) to verify that he/she is
pointing and gesturing appropriately.

<https://www.youtube.com/watch?v=PUkZsfqPmX8>

National broadcasters use more sophisticated displays.

>> If parallax is the only option, I can use an alternate technology that
>> eliminates it -- in favor of other shortcomings.  :<
>>
>> [I *really* don't want to use another plasma TV as they throw off
>> a lot of heat so you can't ALSO use them as a practical TV (which
>> would eliminate the need to STORE the thing when not in use!)]
> 
> Not knowing your actual requirements I'm going to refrain
> from making specific suggestions.