Wesley's Tool-Box

• The Finished Product

It doesn't look much different from the first LCD panel picture because all the other components are completely concealed in the back. It's quite visible that the four bolts are holding the panel to the casing firmly.



This is how the monitor looks from the back. You can find the analog video connector and the DC power input at the top left side, and the OSD controls at the right side. You can see the wires connecting the LCD to the controller, as well as others.

• Putting Them Together

This is how the finished casing looks like. Far simpler than most used in the production monitors, but it gets the job done. Try that with CRT monitors. The components will now be placed here.



There are plenty of space left after placing all the components and connecting them together. The connectors are unique, so there is little chance you'll mix up and get them connected wrong. I can use the leftover space to add other components in the future such as AC/DC converter so I can power the monitor directly from the power outlet. Now all I need to do is to screw the LCD panel in place.

• Assembling the Monitor

Now let's put the components together. We need a casing. It doesn't need to be complex or thick, because the components are lightweight, weight only a couple of hundreds of grams. I used some Plexiglas (pressed acrylic) panels left over from building my new computer (to be introduced in the upcoming article) to accommodate the components in place. First, the back panel:



I put together two panels into one, hence the grey area in the middle. Holes were drilled for placing all the electronic components on it. Next, the side panels:



The LCD panel I used had fastening holes on the left and the right side because it was intended for use in laptop computers, where space must be conserved. Therefore I drilled holes on the side panels to hold the LCD in place.

• Controller / A/D Converter

This component is the 'brain' of the LCD monitor. It drives the monitor to properly display images, and it interprets the computer's video signals to that which can be understood by the LCD panel. LCD's native control signals are in a world of their own: TTL and LVDS to name a few. These are digital signals are significantly different from the analog video signals most video cards use today, and the A/D converter bridges the difference. If the video card uses digital signal like DVI, you'll still need a Digital-Digital converter because DVI and LCD signals are incompatible.



To ensure full compatibility, the A/D converter module usually comes customized for a specific model of the LCD panel. Therefore, if you were to buy an LCD panel, you should buy the A/D converter together as well. I obtain my parts from Eunpa LCD, a direct distributor of LG.Philips LCD panels, the largest laptop LCD producer in the world. Both companies are based in Korea, so take note of this for those living outside the country. The Europeans may want to try Data Display AG, by the way.

For those who are trying to obtain an LCD panel from a used laptop computer, you will probably need to find a company that produces A/D converter module for the model you have. This is because the LCD controller in the laptop computer usually interfaces to the video chip by a proprietary connection instead of a normal video connector, so you won't be able to make a standalone LCD monitor with it. You'll have a good chance of getting the converter module from the companies mentioned above if your panel says it's from LG.Philips, of course.

• OSD Control

The OSD(On-Screen Display) control is not an essential part of the LCD monitor, as it can operate independently without one. However, you will need to have some control over adjustments of the screen, so you will want one if you could.



The OSD control is actually just a set of buttons and LED that connects to the controller. If you have the datasheet for the controller, you can make the OSD control by yourself. By pressing the buttons here, it sends signals to the controller, which in turn adjusts the screen's properties.

• Block Diagram of LCD Monitor

This is how the whole assembly of the LCD monitor is linked. We've already seen the LCD panel part (shown here as LCD Array), but it is apparent that other parts are needed for a properly functioning unit. Let's see what these other components do.

• Inverter Module

LCD does not, and cannot glow like the phosphor in CRT, so some sort light source must always be present. Some of the simple LCD displays use reflective sheet to utilize ambient light to function as a weak backlight. However, complex display like an LCD monitor needs a much stronger light source, and this is why a proper backlight is used. It is actually an array of Cold Cathode Fluorescent Tubes (CCFL) with a light diffusion panel that evenly distributes the light throughout the whole display area. CCFL is a type of a fluorescent lamp known for longevity and evenness in light transmission, and it is often found in scanners and copiers.

An observant reader will know that a fluorescent lamp operates on alternating current (AC). But the rest of the LCD monitor works on direct current (DC) as any normal electronic device would. Therefore, to operate the backlight off the common DC source, we need a module that converts DC into AC. This is the job of the inverter module as seen in the picture above. This component is noticeable by a small transformer that sits on the middle which is usually protected by a plastic cover. The one shown here has 'CAUTION HIGH VOLTAGE' written on it. If you were to take apart an LCD monitor or an old laptop computer, you will discover that the wires coming out of the backlight will lead to this module.