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Hopefully this is a good place for this question... I figured it was too technical for the A/V board of StackExchange.

Question:

Simply put, a recent conversation brought up the issue of the name of and/or reason for the black space ("mesh") between the pixels on an LCD display. Both common types I have examined have this element, including twisted nematode (TN) & in-plane switching (IPS/S-IPS/a-IPS) displays.

Background:

Anyone can see the separation between pixels on most displays 10" and above today. Occasionally the dot pitch is so small that it's very difficult to see this grid/mesh, such as the 200-300ppi+ screens on new tablets (Nexus 10, Galaxy S3) or phones (i-Device Retina displays), but any modern LCD HDTV makes this easy, as the PPI is usually 40-100 at best.

I recognize that there will usually be some visible separation when only one color is fired, as this exposes the dot pitch at its worst by only lighting one color element in each pixel, but even when displaying white this effect is shown.

To illustrate the point from another perspective, another manifestation of the grid is present in projectors that use LCD displays as their source, called the "screen door effect" or "fixed-pattern noise": http://en.wikipedia.org/wiki/Screen-door_effect

Where I am so far:

I have researched much of how various types of LCDs are assembled (links below), and it appears that the cause is the electrode plane required to address and fire the pixels.

Variants and further questions:

Do all types of LCDs have this? Are there any known ways to avoid it with a certain type of display (i.e. keep the electrode element "behind" the visible layer to eliminate its visibility), including experimental/non-commercially-viable technologies?

Any explanation would great, at almost any level of technical knowledge short of a nitty-gritty explanation for SMEs only ;-). Thanks in advance!

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The up-voted and accepted answer is not even wrong. It's pure guessing.

There are no individual pockets in LCD panels. They are two parallel glass plates with special films applied. The plates are held apart with tiny beads (PMMA or Glass)- on the order of 10's of microns.

When two adjacent pixels are set at different voltage levels the LC between the pixels are at an indeterminate state due to the ambiguous fields. In the industry these are called disinclination lines. To hide these lines a black mask is applied between the filters and to increase contrast.

Disinclination lines do not appear in every LCD technology but the black mask increases perceived resolution and display "crispness".

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  • \$\begingroup\$ Even in the "twisted nematode" displays the OP mentioned? ;) \$\endgroup\$ – EM Fields Jul 7 '14 at 16:35
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As the name implies, a liquid-crystal display uses a thin layer of liquid between the electrodes, which is where the change in light transmission occurs. The liquid for each (sub-)pixel must be physically isolated from the neighboring pixels in order to maintain the spatial resolution of the display. There is a spacer between the two layers of glass that has millions of tiny pockets to contain the liquid crystal fluid for each subpixel.

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  • \$\begingroup\$ Great answer. Sorry for the delay. For some reason I didn't get the notification that it had been updated. Thanks! \$\endgroup\$ – Rook Dec 9 '12 at 13:08

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