Type and Definition of LCD Monitors

With manufacturing improving, LCD panel sizes continue to get larger all while prices keep dropping. Retailers and manufacturers throw around a lot of numbers and terms to describe their products. So, how does one know what all these mean? This article looks to cover the basics so one can make an informed decision when buying an LCD monitor.

SCREEN SIZE

The screen size is the measurement of the displayable area of the screen from the lower corner to the opposite upper corner of the display. LCD's typically gave their actual measurements but they are now rounding those numbers. Be sure to find the real dimensions typically referred to as the actual screen size the whenever looking at a LCD.

ASPECT RATIO

The aspect ratio refers to the number of horizontal pixels to vertical pixels in a display. Traditional displays used a 4:3 aspect ratio. Most new widescreen monitors use either a 16:10 or 16:9 aspect ratio. The 16:9 is the ratio typically used for HDTVs. Now a new breed of ultra wide monitors is coming to market. These have a near 2:1 width to high measurements.

MATIVE RESOLUTIONS

All LCD screens can actually display only a single given resolution referred to as the native resolution. This is the physical number of horizontal and vertical pixels that make up the LCD matrix of the display. Setting a computer display to a resolution lower than this resolution will either cause extrapolation. This extrapolation attempts to blend multiple pixels together to produce a similar image to what you would see if the monitor were to display it at the given resolution but it can result in fuzzy images.

Here are some of the common native resolutions found in LCD monitors:

• 17-19": 1280x1024 (SXGA)
• 20"+: 1600x1200 (UXGA)
• 17" (Widescreen): 1280x800 (WXGA)
• 19" (Widescreen): 1440x900 (WXGA+)
• 22" (Widescreen): 1680x1050 (WSXGA+)
• 23.6" (Widescreen): 1920x1080 (WUXGA)
• 23" (Ultra-Widescreen): 2048x1152 (QWXGA)
• 24" (Widescreen): 1920x1200 (WUXGA)
• 30" (Widescreen): 2560x1600

CONTRAST RATIO

Contrast ratios are a big marketing tool by the manufacturers and one that is not easy for consumers to grasp. Essentially, this is the measurement of the difference in brightness from the darkest to brightest portion on the screen. The problem is that this measurement will vary throughout the screen. This is due to the slight variations in the lighting behind the panel. Manufacturers will use the highest contrast ratio they can find on a screen, so it is somewhat deceptive. Basically a higher contrast ratio will mean that the screen will tend to have deeper blacks and brighter whites.

COLOR GAMUT

Each LCD panel will vary slightly in how well they can reproduce color. When an LCD is being used for tasks that require a high level of color accuracy, it is important to find out what the panel's color gamut is. This is a description that lets you know how wide a range of color the screen can display. The larger the percentage of NTSC, the greater level of color a monitor can display. It is somewhat complex and best described in my article on Color Gamuts.

RESPONSE TIMES

In order to achieve the color on a pixel in an LCD panel, a current is applied to the crystals at that pixel to change the state of the crystals. Response times refer to the amount of time it takes for the crystals in the panel to move from an on to off state. A rising response time refers to the amount of time it takes to turn on the crystals and the falling time is the amount of time it takes for the crystals to move from an on to off state. Rising times tend to be very fast on LCDs, but the falling time tends to be much slower. This tends to cause a slight blurring effect on bright moving images on black backgrounds. The lower the response time, the less of a blurring effect there will be on the screen. Most response times now refer to a gray to gray rating that generates a lower time than the traditional full on to off state response times.

VIEWING ANGLES

LCD's produce their image by having a film that when a current runs through the pixel, it turns on that shade of color. The problem with the LCD film is that this color can only be accurately represented when viewed straight on. The further away from a perpendicular viewing angle, the color will tend to wash out. The LCD monitors are generally rated for their visible viewing angle for both horizontal and vertical. This is rated in degrees and is the arc of a semicircle whose center is at the perpendicular to the screen. A theoretical viewing angle of 180 degrees would mean that it is fully visible from any angle in front of the screen. A higher viewing angle is preferred over a lower angle unless you happen to want some security with your screen.

CONNECTORS

Most LCD panels have an analog and a digital connector on them. The analog connector is the VGA or DSUB-15. The common digital interface is the DVI connector. This is a digital interface that is supposed to allow for a cleaner and brighter picture compared to standard VGA connectors. HDMI and DisplayPort are two other digital interfaces that are becoming common. Check to see what type of connector your video card can use before buying a monitor to ensure you get a compatible monitor. Some monitors may also come with home theater connectors including component, composite and S-video.

STANDS

Many people don't consider the stand when purchasing a monitor but it can make a huge difference. There are typically four different types of adjustment: height, tilt, swivel and pivot. Many less expensive monitors only feature the tilt adjustment. Height, tilt and swivel are generally the critical types of adjustments allowing for the greatest flexibility when using the monitor in the most ergonmoic fashion.