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Monitors are critically important because without them a computer cannot be used. A monitor of poor quality can hamper the performance and use of an otherwise very good computer. If the monitor cannot be seen eye-to-eye, working on the computer can be unpleasant. This is why people often end up spending more on their monitor when buying a new computer as they do on the computer system itself. The monitor physically connects to the video card and allows the visual output of information and current status. The vital element of a computer monitor is the ‘Cathode Ray Tube’ (CRT). The characteristics of a CRT primarily determine the quality of the image. In fact, the CRT defines the whole monitor so much that often the monitor is just called the CRT. The CRT is the costliest part, within which are three electron guns. The CRT is the heart of the monitor. The sign of a good monitor is a good CRT; extra fancy looks, controls and other features cannot make-up of a bad tube. The CRT is lined with phosphorous material, arranged into an array of millions of tiny cells, usually called dots. When a stream of electrons strikes the phosphorous material, these dots glow. The dots can be seen when the monitor is looked at closely. A set of electron guns, at the back of the monitor produces a controlled stream of electrons. The three electron guns on a colour monitor, control the display of red, green and blue light respectively. The surface of the CRT is arranged so, to place the dot in specific pattern. Separate video streams for each colour come from the video card, which allow different colours to have different intensities at each point on the screen. By varying the intensity of the red, green and blue streams, the full rainbow of colours is made possible. These guns start at the top of the screen and sweep very rapidly across from left to right, then return to the left-most position one line down and sweep across again. This is repeated to cover the entire screen. Thus a picture is produced on the screen. In performing this sweeping motion, the electron guns are controlled by the video data stream coming into the monitor from the video card. This varies the intensity of the electron beam at each position on the screen. The intensity-control of the electron of the electron beam at each dot, controls the properties of each pixel on the screen like colour and brightness. Imagine the entire screen is drawn in a small fraction of a second. The monitor must redraw the picture many times per second to avoid having the screen flicker. The surface of the CRT glows for a small fraction of a second before beginning to fade. As it begins to fade it should be renewed. This rapid redrawing is called refreshing the screen. The Monitor is different from the other components of a computer; it isn’t responsible for any hardcore computing, but rather displays the visual output from the computer as generated by the video card. It plays a significant role in the following important aspects of the computer. The monitor determines the quality of the image, which has a significant impact on how comfortable the computer is to use. Poor quality monitors lead directly to eyestrain and sight problems and can ruin the computing feel. As most monitors are interchangeable and can be used on any similar computer, they are naturally flexible to adapt to or upgrade to a new machine. Compared to other components of a computer that become dated quite quickly such as a microprocessor, a good monitor can be used for many years. Advanced high resolution or high colour depth video modes requires support from the monitor. A monitor, who cannot handle the high resolution at high refresh rates, is useless. Monitors today are commonly called as analogue monitors, while older monitors are referred to as digital. The circuitry that controls a computer is digital but the colour signals received from the video card is analogue. Originally, monitors used digital colour signals. In case of CGA and EGA video cards, each colour had only a certain pre-set number of colour levels, which were supported. Digital video signals are sometimes referred to as ‘Transistor-to-Transistor Logic’ (TTL). With VGA standard setting in, the switch took place to analogue colour thus allowing more possible shades of each of the three primary colours. An analogue signal supports a continuous range of values, so the number of different colour levels is in theory unlimited. Actually, standard analogue colour uses a range of 256 different values for each colour. The phase from late 1980’s, saw a lot of VGA cards in use. Some companies released monitors that could respond to both analogue and digital signals. These used a toggle switch. These are obsolete now. Modern monitors and video cards use analogue signalling. Labelling a monitor as analogue or digital depends on the type of colour signals it uses, since analogue monitors may have analogue or digital controls. However, in most cases the monitor itself is analogue either way. Pixels are the tiny dots that make up the screen image, arranged in rows across the screen. A screen image may have between 480,000 and 1,920,000 pixels. The CRT screen gets refreshed many times per second. Refresh rates are measured in ‘Hertz’ (Hz), which means times per second. Every pixel uses a display of different colours. The number of colours displayed is called colour depth. Colour depth is measured in bits i.e. 8, 16 or 24 bits. All video cards have some RAM; how much depends on the desire colour depth. In the mid 1990s the video cards used to have 1, 2 or 4 MB RAM for normal usage. Today they have 16, 32 or more MB RAM onboard. This is good for gaming. A dot pitch specification represents how sharply an image can be displayed. It is having the smallest physically present element on a monitor. Typically, monitors with .28 mm are present on personal computers. A pixel is the smallest element that can be controlled via software. A collection of pixels causes the monitor to glow. When the monitor is set to the highest possible resolution, the physical size of pixel represents the size of dot pitch. For lower resolutions, a conglomeration of pixels represents a given dot-pitch. In simple terms, consider the monitor being made up of collection of tiny bulbs placed extremely close to each other. To illuminate a particular spot on screen, the relative bulbs glow. A higher resolution monitor implies greater amount of viewable workspace in a given amount of area. A 15” screen with a maximum resolution of 1024 x 768 means it has a total of 1024 pixels width wise and 768 pixels height wise, that’s a total of 7,86,432 pixels on a 15” screen. If the monitor is primarily used for surfing the web, reading and doing text-related work, a 15” monitor capable of 1024 x 768 resolution is recommended. For those whose work revolves intensely around PhotoShop and other graphic editing tools or simply love playing games, a 17” monitor capable of more than 1024x768 resolution is recommended. If a pixel continues to glow continuously at high intensity, it may flicker i.e. change the intensity with which it glows thus causing eyestrain. In case of monitors, an image is constantly being redrawn at a particular interval expressed in seconds. Any screen capable of doing refresh rate at a frequency grater than 75 Hertz is a good choice. Having a proper display card with adequate amount of RAM is an absolute necessity. If a 17” monitor is connected to a video card with a meagre 1 MB amount of VRAM, it hardly makes any sense. Although normal applications such as word and solitaire will work without any glitches, watching movies on it will be a poor show. A good video card with adequate amount of RAM enhances the monitor’s performance enabling us to truly experience the joy of big things. For someone who is extremely fidgety with the actual position of monitor and who prefers to sway and swing it every now and then choose one that has a good base and can be moved easily. If the monitor is going to be used by more than a single person, ergonomics plays a vital role. Not only do two people view the monitor at different angles, the way they operate the mouse, their posture their height and all such factors are important. Lay hands on a monitor whose height and angular position can be adjusted. Computer screens tend to emit radiations and prolonged exposure to them is harmful. Though protective ultra-violet screens are available in the market, their presence simply darkens the screen and some of the non-certified cheaper protective screens are prone to speed up the process of forming a cataract in the eye. A monitor whose emission matches MPRII or TCO standard is good. Since a monitor is powered on for more than 8 hours per day efficient utilization of power is mandatory. Always prefer a monitor that bears an ‘Energy Start’ logo, which indicates that it is manufactured according to the norms set by U.S. EPA. A 21” isn’t what it exactly billed as. These digits represent the diagonal width of the screen. So even if a 21” monitor is bought then the image size displayed will be 5% to 8% smaller. For malls and departmental stores, special 8” and 12” monitors are available at extremely low prices. Quite recently, the amount of electronic waste being piled up has grown significantly. While buying a monitor by replacing the old one, ensure that the old one is displayed in an environment friendly manner. Branded computer manufacturers such as HP, take special care in disposing old and defective monitors. While purchasing a monitor, buy one that’s made up of recyclable material. Almost all manufacturers make monitors or at least the accompanying rectangular box out of recyclable material. Installing monitors without proper device drivers can be a horrendous task. Quite rightly, some people prefer calling “Plug-n-Play” devices as “Plug-n-Pray”; plug and pray for them to start functioning. Place the monitor on a firm base. A normal 14” monitor weighs more than 4 kilograms and it’s essential for the platform to be sturdy. If a few creaks are heard, better replace the platform. Ensure a minimum of ½ feet open space on either side and on top of the monitor. During prolonged operations, monitors tent to become hot and proper ventilation can ensure their longer life. To install a monitor, simply remove it from the box and place it on a sturdy platform. Connect the power cable at the back of the monitor to a 230 V AC supply. Some monitors bought from outside India require 110-120 AC volts for operation and connecting them to a 230 V AC supply can cause them to explode. If the monitor happens to be one of the rare species, check for a knob that switches between 120V and 230V AC or buy a step-up transformer. Connect the data cable to the display card. Some monitors have an onboard display card while others have a PCI/AGP display card. With the latter ones, one should make sure that the PCI/AGP card is inserted firmly inside the slot. Else a loose contact may involve hours and hours of worthless brain storming techniques trying to figure out the exact nature of the problem. Once the connections are done properly, switch on the power supply for the monitor and boot up the computer. ‘Liquid Crystal Display’ (LCD) works on a simple principle in which the liquid exhibits different properties at different temperatures. At lower temperatures, these liquids appear hazy and opaque, but at high temperatures they become clear and transparent, allowing light rays to pass straight through them. An LCD screen is made up of a number of different layers sandwiched together, which are collectively responsible for producing images. Liquid crystal materials require an external source of light to glow. Apparently the last layer consists of a fluorescent white colour back light. Ahead of this layer is a polarizing layer primarily responsible for an even distribution of light throughout the display area. Next is the liquid crystal layer, which forms the crux part of every LCD. It is made up thousands and thousands of diminutive crystals each kept in tiny containers neatly arranged in an n-dimensional matrix. This array of a-dimensional matrix has two walls, each densely filled with electric connections connecting each and every liquid container. Each of these electrical connections is connected to a thin-film transistor, more popularly known as an active matrix. When in dormant state, the crystals are arranged randomly tie-in twisted stated, is opaque to light and nothing can be seen on the display. On applying voltage, they get excited; untwist themselves to varying degrees depending upon the magnitude of voltage thus allowing lights of varying intensities to pass through. This light then passes through colour filters predominantly consisting of three primary colours red, green and blue. Each colour forms a sub-pixel and a collection of three sub-pixels of different colours make up a single colour pixel. A total of 256 shades per pixel can be produced on applying different voltages to each of the sub-pixels. This builds up to form a total of 16.8 million colours 256 shades of red x 256 shades of green x 256 shades of blue. On the additive mixing of these three primary colours in various combinations and quantities, a variety of hues specific to each pixel are produced. The thin film transistors are capable of turning on and off at a very high rate, typical switching time being 0.013 seconds. To make a spot glow on the LCD, the corresponding row of pixels is selected, switched on and corresponding voltage is applied to the correct column. At the same time, the remaining columns are switched off since no voltage is applied to them. This charge is stored in the capacitor and the capacitor discharges only when the next refresh cycle is due. This entire switching takes place at a very fast pace and due to persistence of vision, we are able to see the entire display without any flicker. A typical LCD display capable of a 1024x768 resolution, consists of 2,359,296 transistors 1024x768x3 sub-pixels on a single plate of glass. With so many transistors, it is difficult to get all of them in working condition and with every LCD display there are a few bad transistors or pixels. But because of the humongous amount of pixels, a few hundred bad sub-pixels rarely make a noticeable difference. Also, most manufacturers have a standard quality check procedure and if more then a stipulated amount of pixels go bad, the displays never make their way up to the consumer market. As against CRT displays, which are measured diagonally, LCD display measurements give us the exact viewable area measured along height of the display. LCD panels are lightweight and require much less space than CRT monitors. Since the images are crisp, clear, sharp and flicker free LCD’s are easier to retain. LCD’s have lower levels of radiation emission as compared to their CRT counterparts. LCD’s have a large viewing angel of 120 degrees horizon making it possible to view the screen from even the corner of an eye. Compared to CRT monitors, LCD consumes very less energy thus reducing overall power consumption electricity bills. One of the biggest advantages of LCD monitors is that they are compact and lightweight. LCD monitors allow scaling images of other resolutions, but the sharpest result can be seen on the default. LCD monitors are backlit and have different levels of brightness. The brightness rating for a monitor is commonly referred to as ‘CD/M2’. Higher the value, brighter it is. To increase display size, manufacturers add more pixels and transistors. As they do so, they also increase the chance of including a bad transistor in a display, resulting in a bad pixel. All displays can be adjusted with the help of panel controls. There are different kinds of panel controls. Some models offer an auto sync button, which automatically synchronizes the brightness and contrast ratio. If the LCD monitor is touch sensitive screen then the technology being used for these panels also differs among models. ‘Display Data Channel’ (DDC) is a standard set by the ‘Video Electronics Standards Association’ (VESA). This feature allows the monitor to send the computer information like the resolutions, signal rates, and power-saving modes supports. LCD’s are digital, hence the quality of the signal may diminish, as it is converted form digital to analogue and back again. Some LCD’s have difficulty synchronizing converted from digital to analogue and back again. Some LCD’s have difficulty synchronizing correctly to an analogue signal, resulting in pixel jitter. If work with more than one computer is needed but have space for only one display then a model with multiple inputs is required. These units will have a single button or switch on the front panel, making it easy to switch between the two displays. A mounting arm even allows hanging the LCD on the wall creating more and saving more space. There are some models, which cater specifically to those who work on graphic or design applications. They are particularly helpful for architects or furniture designers, anyone using CAD type applications for that matter. These might be heavier on the pocket but easy on the eyes due to flicker free. LCD monitors are not good as CRT when it comes to hardcore gaming. Digital interfaces provide better LCD images but the environment is minor for many models. So unless the graphics card has digital connection, an analogue connection will be good enough. Some manufacturers build hubs into their displays, and others offer them as extras at an additional cost. These hubs are a convenient place to plug in USB devices. Very few monitors use the USB connection to allow access to the monitor’s controlling circuitry. This allows adjusting the monitor from the keyboard instead of using the monitor’s buttons. If the monitor is touch screen type, then there may be additional touch screen drivers too. Refer to the manual thoroughly for step- by- step instruction on their installation. There are a few video cards, which support DVI output mainly some high-end graphics cards like GEFORCE, which is a requirement for a digital display. An analogue connection to the LCD monitor has enabled users of virtually and video card to use this display.