Although some specifications of LCD and CRT monitors have the same or similar names, the content and importance are different. So there are following guidelines for you when you choose a monitor.

Port

　The most difference among current various monitors is different port, i.e. analog or digital port. Below are their different characters.

　Most of LCD monitors use analog port while few new type monitors use digital port. Some medium-high class monitors use DVI port to decrease picture distortion.

Visual Angle

　The visual angle of LCD monitor on current market is symmetrical in horizon direction, but different in vertical direction. The vertical visual angle is usually smaller than the horizon angle. Because of refraction and reflection, color will be distorted when you watch the screen out of visual angle. Visual angle usually indicates horizon visual angle. The larger the value, the larger the angle from which you can see the picture on the screen clearly. The horizon visual angle usually ranges from 100～150º and vertical visual angle from 80～120º.

Brightness and Contrast

　Brightness is one of major specifications of a LCD monitor and measured with cd/m2 or nits. Its value ranges from 100 to 130nits. Of course, a specification can not tell all functions of a product. High brightness does not mean a good product. The uniformity of brightness is the key and closely related with the quantity of luminous source and reflected mirror and the solution of configure, which can not be found in the product manual. The brightness at a location far away from the luminous source is surely dark.

　Contrast is the ratio of maxim brightness to minimums brightness. High contrast can make the picture clearer. But the color will be distorted if the contrast is high enough. The contrast of most of monitors ranges from 100:1 to 300:1. As brightness, there is no an effective, fair and public standard to judge contrast now. Instead, we can only judge it with eyes.

　Brightness and contrast must be well matched so as to create beautiful picture quality. Generally speaking, high grade monitors usually have smart function to adjust image automatically to the best match of brightness and contrast.

Response Time and Renew Frequency ( Scanning Frequency)

　Response time is the characteristic specification of a LCD monitor. It indicates the response speed of all pixels of a LCD monitor for input signals. It is measured with ms. Short response time indicates fast response speed of pixel. When response time is long, the moving image or even mouse will create “tail” or shadow. The response time of current LCD monitors should be below 30ms.

　LCD refreshing frequency indicates displaying frame frequency, which means the time needed to refresh the frequency by each pixel. It is related with scanning speed and the ability to control the screen flicker. Because eyes can find whether the CRT scanning frequency is high or low, the scanning frequency must range at least from 65HZ to 70HZ and then the screen will not flicker.

LCD Pixel Pitch

　LCD pixel pitch is similar with CRT dot pitch. But the importance of LCD pixel pitch is less than that of CRT dot pitch for the functions of a monitor. The value of LCD pixels is comparatively fixed. So, the pixel pitch for all LCD monitors is the same as long as the size and resolution are the same. For example, the pixel pitch is 0.297 mm for all 15’ LCD monitor with resolution of 1024×768.

　In addition, we should also pay attention to the promises of LCD panel quality and MTBF (Mean Time Before Failure) declared by the suppliers. So it is a reliable way to choose famous and familiar suppliers.