1 - Introduction
Monitors today are primarily of three kinds, CRT, LCD and plasma. CRT and LCD are the common ones for computers. CRT (Cathode Ray Tube) monitors could be monochrome or colour monitors. Now-a-days you rarely see a monochrome monitor. CRT monitors are less expensive, larger in size, give good image quality but may flicker due to convergence and focus problems.
| However, LCD monitors, are comparatively expensive, occupy less desk space and give excellent image clarity and quality and are most suited for movies, animation and gaming on the computer. However, as monitors can cost anything from below $100 to more than $1000, a whole lot of parameters need to taken into consideration before zeroing in on the right monitor. |
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2 - Standard Features
Every monitor comes hardwired with some basic features. The following covers a few of those.
2.1 - Resolution
Resolution indicates the amount of detail that can be displayed on the screen. Resolution is measured in dpi (dots per inch) or ppi (pixels per inch). These refer to the number of horizontal and vertical lines of the ‘ dots’ or the ‘pixels’. The higher the resolution, the better is the image quality because you will able to view more information at the same time. CRT monitors can display different resolutions, even ones higher than their original physical resolutions. LCD monitors however work best at their native resolution which is based on their matrix of LCD cells and hence this is the best resolution for display on screen. Most of the computers today work around resolutions of 1200x768, 1280x1240, and 1600x1200. Higher resolutions such as 1600x1200 are most suitable for gaming and animation applications.
2.2 - Size / Dimensions
Size is usually a key factor when choosing the monitor as it depends upon the desktop space available. When space is a major constraint, LCD displays are apt as their base width is about a hand span only and even their clarity is higher than that of CRT monitors. A 15” LCD is at times clearer than a 17” CRT, occupies less space, weighs about half a CRT monitor of the same length and consumes a lot less power. However, if space is on hand, then CRT monitors offer good quality displays at less cost. Also, the larger the screen size, the easier it is on the eye as text and image sizes are larger and this reduces the strain on the eye. All screen sizes are measured diagonally across the screen, but this can be misleading as it includes the plastic frame about it for CRT monitors. But for LCD monitors, the size usually is the viewing size.
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2.3 - Refresh Rate
Refresh rate indicates the number of times the screen of a CRT monitor is redrawn. It is measured in hertz. A very low refresh rate will lead to a flicker on the screen and eyestrain. Refresh rates are usually 75 Hz, 85 Hz or 100 Hz. |
2.4 - Dot Pitch
Dot pitch is the distance between two dots or pixels or in a LCD monitor between the LCD cells. The shorter the Dot pitches, the better, as there are more dots in the area and hence better image quality. Dot pitch is usually measured diagonally, but some lower end manufacturers measure it horizontally and hence it can be misleading. For CRTs it is usually 0.21 mm.
2.5 - TCO 95/99/03
Electromagnetic emissions by monitors are quite harmful and even at the time of disposal they can cause a health hazard. So certain standards have been set to determine the emission levels of monitors and the “low emission” monitors that have certifications like MPR II and TCO95/99/03 are preferable to others. Now-a-days most monitors are TCO certified as they adhere to these guidelines that look into the ergonomics, emission, energy and ecological concerns. CRT monitors however use more power than LCD monitors.
2.6 - Color Depth / Bit Depth
Colour depth refers to the number of colours that a monitor can display. Effective colour display of a monitor depends on this factor combined with the prowess of the graphics adapter. The colour data is stored by the pixels in bits and the more the bits the better the colour display. The LCD monitors use a combination of the 3 primary colours red, green and blue with varying intensity to create a colour palette of 16.8 million colours at best. CRT monitors can usually display any number of colours and it is not much of an issue for them. Colour depth can range from 1-bit for black and white, 8-bit for 256 colour display, 24-bit true colour, etc. Bit depth of a monitor refers to the number of bits per pixel and most monitors used for hi-end graphics display work around 24-bit. The monitors can have colour depths such as 0.294 mm.
2.7 - Pixel Response Time
Pixel response time indicates the time it takes for a pixel to change the colour on the screen, i.e. go from active state to passive state. This affects the refresh rate of the monitor. It is measured in milliseconds. The lesser the response time, the better. Earlier monitors had longer response times that lead to blurred images or ghosting, but now it is hardly visible. The response time for LCDs can be 8-16 ms but some are also 4 ms.
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3 - Adjustable Features
3.1 - Contrast
Contrast is the difference in colour and brightness between an object and its background that makes it visible. When is comes to monitors, contrast is determined by a number of factors such as depth of colour, brightness, shading of an area, the field of view of the object, properties of the picture source or file and at times the angle between the screen surface and the observer's line of sight. It is described as a ratio and for an entry level monitor a ratio of 400:1 is acceptable, while higher-end ones may have ratios like 1000:1.
3.2 - Brightness
Brightness indicates the luminescence of an object. For monitors this is measured in nits where 1 nit is equal to 1 candela per square metre. Monitors can have brightness ranging from 200, 250, to 1000 or more. The brightness in LCDs is due to many backlights, but their warranty may differ from that of the LCD as they are fragile. So check it out individually.
3.3 - Aspect Ratio
Aspect ratio of an image refers to the ratio of its width to its height. Pixel aspect ratio refers to the size of individual pixels of an image, irrespective of the actual ratio of the image. Aspect ration can be 4:3, 5:4, etc. The more the ratio, the wider it gets. |
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3.3 - Connectivity
Some monitors can be connected to two computers, while some with the help of USB ports or hubs can be connected to a number of peripheral devices such as; mouse and printer. These are usually at the back side of the computer, but connecting to a monitor is more convenient.
3.4 - Viewing Angle & Positioning
LCDs do not give good viewing angle like CRTs, either horizontally or vertically. When viewing from an angle or from the sides the image in an LCD may look a bit off or faded. Some LCDs come with a viewing angle of 100 or so. Try for a LCD with angle of 140 – 180. One big advantage of LCDs over CRTs is that they can be positioned differently as they are not as heavy or occupy as much space as LCDs. Some LCDs can tilt or swivel or pivot at 90©, thus giving you flexibility for viewing and presentations.
The monitors usually come with a menu panel that has settings to adjust options such as brightness, contrast, OSD Controls, factory reset, Auto Image Adjust, Input Select, Color Adjust, Information, Manual Image adjust, Position, Sharpness, Language, Anti Static Size, Tilt, etc. these are useful in adjusting the monitor to your convenience.
3.5 - Power Consumption
Monitors consume a lot of power, at times as much as or even more than the computer itself. LCDs however consume far less power than the CRTs. LCD monitors may consume power such as 38 watts while CRTs may consume power such as 100 watts.
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4 - Warranty & Maintenance
Before you invest in a new monitor, it may be wise to examine maintenance and warranty options. Since, monitors are expensive and are usually expected to last about 5 years; the warranty period may be an important consideration. It may range from 1-3 years. Also one must check exactly what is covered under the warranty, as warranty period for different parts may vary. LCD monitors may have a problem of dead pixels. The warranty may depend upon number of dead pixels and these may at times cause a problem in viewing the images.
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