There’s a pretty good chance that you’re reading this article on either an LCD screen or an LED screen. We’re not here to discuss the differences between the two (LED is basically LCD’s prettier, slightly more expensive younger sister). Instead, we’re going to take a look at how your monitor works. How does an image go from an electrical signal to a picture on a screen? How does your monitor interact with your PC? Last, but not least,what’s the difference between the two forms of liquid displays?
The Screen
The screen of both LED and LCD screens both utilize a unique form of matter which is somewhere between a solid and a liquid. The molecules of this substance have a very unique structure which makes them particularly susceptible to electrical currents, actually changing based on the level of voltage applied to them. The molecules of the substance in an LCD display are typically in a phase known as the Nematic phase, and has a naturally twisted molecular structure.
The screen takes this ‘liquid crystal’ and places it in between two plates of polarized glass and a positive and negative electrode, with polarizing film on each side of the glass opposite the electrodes. Finally, put the whole array in front of a mirror, and then put the screen on the side opposite this mirror. LCD displays add color filters to the mix- one for each of the three primary colors. Most LCDs of this nature feature fluorescent tubes, usually positioned somewhere around the screen.
The glass plates usually feature something known as a “Active Matrix,” which each of the glass plates featuring a matrix of tiny transistors which hold a charge. Depending on which of the transistors is charged, different pixels will appear onscreen.
LED(Light Emitting Diode) displays vary from LCD displays in that, in addition to the standard LCD array, they utilize clusters of small, electrically charged diodes as a backlights for the liquid crystal layer. This allows for more vibrant images and deeper colors. Each diode contains a certain number of electrons, as well as a small vacuum in which electrons cannot exist, known as an “electron hole.” the color of a diode depends on the number of electrons and the size and shape of this hole.
The Bridge Rectifier
The Bridge rectifier converts Alternating Currents into Direct Currents- the latter of which is necessary to change the shape of the crystals which make up the display. It consists of a circular piece of plastic and a rectangular piece of plastic held together by four wires.
Filter Capacitor
This device basically prevents your display from shorting out due to the voltage getting too high. It basically manages currents and voltages, keeping the voltage from getting too high.
SMPS Transformer
The name of the game here is “efficiency.” The SMPS transformer transfers passing energy in a way that allows the display to run effectively without using too much power. It’s usually right on top of the spot where the monitor’s power supply connects.
Schottky Diodes
Designed to prevent the loss of voltage (voltage drops) and allow for more efficient start-up times, Schottky diodes are semiconductors are usually positioned next to or above the output filter capacitor.
Output Filter Capacitor
The OF Capacitor works with the Shottky Diodes in order to keep voltage as high as necessary for the operation of the monitor and to dissipate excess voltage.
The CPU
Pretty much your run of the mill CPU- this device does basically what you’d expect, and controls most of the monitor’s operation, in addition to managing connectivity where other devices are concerned.
Fuse
If something overloads within the monitor, chances are good that the fuse is going to be the first thing to go- after all, that’s what it’s designed for. If current gets too high, the fuse will melt and necessitate replacement.It’s basically a failsafe switch.
Opto-Isolator
Yet another device designed to mediate voltage, the Opto-Isolator prevents high voltages from transferring into components they’re not supposed to.
Pages Cited: [eHow] [How Stuff Works]
Image Credits: [Tree Hugger]
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The information in this article is far too condensed in my opinion: so much so that it gives entirely the wrong impression and causes confusion in numerous cases throughout the article. Each component-part mentioned would be short-changed without its own article. ( I’m a [maybe overly-pedantic] qualified electronics technician.)
This is the most poorly written collection of half truths and random factoids of any article I’ve ever seen on PC Mech, or most anywhere, for that matter. The description of the screen is totally inadequate (what does ‘LCD’ stand for, for starters), and the rest of the items described are a random collection of electronic components, very poorly described, and found in almost any piece of home electronics today. Most of them could be lumped into “oh, yes, the LCD monitor (or computer, or cordless phone, or stereo, or… etc.) has a power supply that provides electricity in the form needed for the device to function.”
Read the author’s objectives in the first paragraph. Almost none of his stated objectives are met in the remainder of the article. How can you publish such garbage?