BiDi Screen: Depth and Lighting Aware Interaction and Display

Matt Hirsch1      Douglas Lanman2      Henry Holtzman1      Ramesh Raskar1
1MIT Media Lab         2Brown University

LCD Disassembly

Introduction

The BiDi Screen is assembled by modifying a commercial off-the-shelf LCD screen. This page describes the process of disassembing a Sceptre X20WG-NagaII 20.1 inch LCD panel, and removing the diffusing polarizer layer. This is a destructive process that will irreversably damage your display.

This tutorial from 3M gives a good overview of the parts of a modern LCD panel.

Procedure

Set LCD face down on a cloth or soft surface

Remove the pedistal by removing the four screws that affix it to the back of the screen.

Removing the pedistal

Remove six screws from the back of the panel. They are inset in the plastic case.

Snap apart the front of the case from the edges. This will require a screwdriver or small prybar.

Prying apart the case

Flip the screen onto the back.

Remove the control panel (green). It is affixed to the front of the case with two screws.

Screen, opened

Flip the screen back onto its face, making sure that it is resting on a soft surface.

Opened screen, face down

Disconnect the power supply from the metal backing. This will involve removing three screws that affix the power supply, one screw affixing the ground strap, and two screws affixing the black A/C plug.

Removing the power supply

Disconnect the screen supply cable and backlight supply cables.

Disconnecting screen supply cable Backlight supply cables

Disconnect DVI and VGA connectors from the back. (Two bolts each).

Disconnecting the DVI and VGA connectors

Remove the metal backing. Remove any screws affixing the metal backing to the backlight.

A screw to be removed Metal backing removed

Remove backlight (CCFL) clips.

Removing the backlight clips

Remove the cover from the screen driver electronics. (Three screws). You will not be able to fully remove this cover until you complete the next two step. Note that the power and control panel wires can be slipped through the cover without removing them from the video driver board.

Cover to remove (DVI/VGA plugs already removed)

Remove the DVI/VGA connector from the board. Carefully pry up the edges. The plastic housing for this plug is delecate.

Controller board (DVI/VGA port circled)

Remove the video driver board from the metal backing by shifting it and bending up the metal clips holding it down. Take care not to break the delicate connections in the four ribon cables connecting it to the LCD panel

Remove two small screws from the right side.

Two small screws to remove

Unclip the metal retaining clips from the sides of the backlight panel.

Metal clips holding on plastic case

Remove the metal cover from the front of the screen.

Metal cover on front of screen

Peel up the diffusing polarizer layer which is affixed to the front of the screen with adhesive. It helps to have a razor or sharp knife to pry up one corner of the polarizer. Once started, it will peel back like a sticker.

Peeling up diffusing polarizer

Remove the adhesive using a solvent such as paint thinner or acetone, and soft cloth. Do not get the solvent on the electronics. This will be a time consuming step, taking up to three hours. Other LCDs we have disassembled have had less sticky adhesives that remain attached to the polarizer.

Adhesive covered screen Removing adhesive with solvent

At this point, the LCD is ready to use in a BiDi Screen. For interest's sake, I've included some pictures of the backlight disassembly below.

Backlight running without LCD panel.

Backlight without LCD

LCD running seperated from backlight. This gives a good indication of the lighting efficiency of the LCD panel, which is low.

LCD sans backlight LCD sans backlight (running)

Layers of the backlight.

Backlight layers

Cold cathode tubes.

CCFL tubes from one side of backlight.