Date: Thu, 11 Oct 2001 19:41:23 +0000
From: "Matthew Hanson" <[EMAIL PROTECTED]>
Subject: Re: [LIB] Re: [LIBRETTO] Re: Nuts and bolts of impoving LCD

>Date: Thu, 11 Oct 2001 17:23:58 +0800
>From: Raymond <[EMAIL PROTECTED]>
>Subject: Re: [LIB] Re: [LIBRETTO] Re: Nuts and bolts of improving LCD
>
>
> >Looking over how the light originates from the rear, I wouldn't >think 
>that even using a mirror back there should cause image >doubling, as what 
>comes from the back is only white light.
>
>Problem is if light is coming in the FRONT then the light passes through 
>the image layer TWICE. Just look at your wristwatch from the side under a 
>relatively direct source of light to see this.

Okay... so light entering from the front may be able to do this to some 
extent... but I would think that mirror in the rear would strengthen
the fluorescent bulb's light output through the front of the panel to a 
greater degree than a diffusion backing.  Mirrors HAVE been used in other 
LCD constructions from what I've read (albeit the ones I read about were 
primitive).  If a filter was applied to the front of the panel that blocked 
light entering from any angle except from straight ahead, say at about an 7 
degree spread... do you think that the screen image created by brighter 
fluorescence and a mirror backing might overpower any doubling of the image 
from light entering from the outside?

> >  Bouncing white light escaping through the back should only >  intensify 
>the source light.
>
>ESCAPING through the back?

Man... since my accident I tend to think in complete sentences, and write 
only part of them. I used to speak like that too. I still have problems 
getting out some sentences when I'm tired, but I am improving from the 
condition called aphasia.

Let me fill in the gaps:

-- Bouncing white light that would otherwise escaping through the back of 
the LCD back through to the front of the screen should only intensify the 
source light. --

I'm assuming that whatever the material is on the back side of the 
illumination layer does NOT have a reflective layer of any kind behind it, 
and that some light being generated by the fluorescent bulb(s?) is lost 
through the back side of the illumination/diffusion layer.


> >Increasing the source fluorescent lamp(s) output is obviously a must.
>
>Is it? Wouldn't it be better to use reflected light so the 'intensity' of 
>light coming off the panel is proportional to ambient light?

Wouldn't it be good to set things up so that the light output from the LCD 
is greater than the ambient light?  I kind of thought that the ambient light 
being brighter than the LCD light output was what the problem was.  Wouldn't 
pumping up the lamp output help there?

> >  But I wonder if increasing the voltage to the TFTs would rotate >  the 
>LCs more and get the light angle more aligned with the front >  polarizing 
>filter.
>
>Its not power that rotates the LCs, its electric field. And the intensity 
>of that field effectively determines how far on or off each pixel is in 
>terms of blocking light.

That's what I was struggling to say. I'm a bit new top all this.  Not fully 
understanding how things work, I thought that more voltage to the TFTs may 
create a stronger field, and thus rotate the LCs to better align their light 
angle to the polarizing layer.  Though if Toshiba already has set things up 
so that the two angles coincide, rotating any further would begin to dim the 
display, right?

>kitty libby?

Heh... a reference to Neil's comment when I got the LCD in my 70CT working 
again.  :-)

Matt


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