There is a saying that a surveillance system is only as good as its monitor. If this is true, recent advances in monitor technology ensure that an operator can purchase a high quality system. There are two types of security monitors: the older, bulky CRT monitor and the newer, sleeker LCD monitor. For many reasons which will be elaborated upon, it makes sense to purchase a CCTV LCD monitor over a CRT.
CRT stands for Cathode Ray Tube. It is the traditional box type of monitor or television. The inside of a CRT monitor consists of three phosphor layers, one each for red, green, and blue colors. When these layers are hit with electron beams, energy from the electrons is converted into light radiation. Different compositions of the phosphor create different colors.
LCD stands for Liquid Crystal Display and it is actually not new. It was first introduced in 1970 but for a long time it was inferior in image quality. That has changed with advances in technology, however. The inside of an LCD monitor consists of a liquid suspended between two glass or plastic panels. The liquid crystals are naturally aligned to let light pass through except for when a current is applied. In this case, it blocks light, turning the affected area dark. Different amounts of light are made to pass through the crystals by altering the amount of current used. Red, green, and blue chambers inside the monitor produce color when varying amounts of current is passed through these chambers. |
CCTV LCD monitors should be favored for surveillance purposes over a CRT for several reasons. First, they provide better image quality than CRTs. CCTV LCDs produce a sharper, brighter picture because they can process CCTV signals at a higher resolution. These monitors are also more responsive than CRTs, making them ideal for live video monitoring. They are much lighter and less bulky than CRT monitors so they take up much less room. They also come in large sizes for multiple camera viewing situations. A big advantage of CCTV LCDs over CRTs is that LCDs do not suffer from magnetic interference. Speakers, for example, do not need to be shielded to be used in conjunction with the monitor. Another advantage of a CCTV LCD is screen flicker is not an issue. With CRT monitors, low refresh rates leads to screen flicker, an annoying occurrence.
Despite all these advantages, there are some disadvantages to a CCTV LCD. One is the contrast ratio. It is easier to produce higher contrast in CRT monitors because the electron gun can be turned off for true blacks. In an LCD the backlight is always on so a certain amount of light will always show through. Because of this, buyers should be aware of an LCD monitor’s contrast ratio. An effective ratio is 400:1. Another drawback is LCD monitors sometimes generate dead pixels, or areas of the screen that remain black because they no longer function. If the monitor is under warranty, most manufacturers will repair dead pixels, but this leads to system downtime. Even with these drawbacks factored in, an LCD monitor is clearly the best choice for your surveillance needs.
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An important distinction should be made between CCTV LCD monitors and regular LCD monitors. CCTV LCD monitors have a processing scaler, which is a device designed to display the best possible picture from a security camera by upconverting the signal. Also, CCTV LCD monitors have a BNC input in addition to a VGA input. Regular LCD monitors only have the VGA input because they are designed for use with a PC only. Most modern DVRs come with BNC and VGA outputs, so a PC LCD monitor would work with a surveillance system, however for the best possible picture a CCTV LCD monitor is recommended. There is a price difference, though, as CCTV LCD monitors can cost as much as two to three times more than a regular LCD monitor. This is due in part to the additional electronics, such as the processing scaler, and because LCD monitors with BNC inputs are produced in much smaller quantities than regular LCD monitors and therefore the production costs are higher.
A CCTV LCD monitor from AG Neovo.
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