In the long and arduous innovation process of the PC industry, with the advancement of display technology, the classification of displays has become more and more detailed, which can be divided into flat-panel displays (FPD) and cathode ray tubes (CRT), also known as flat-panel displays. CRT is the overlord of the display when FPD is immature, the technology is mature, the cost is cheap, the color is rich, and the response time is short. However, due to its huge size, flicker, image distortion and other fatal defects, the civilian market share is gradually replaced by FPD. A flat panel display, as the name suggests, is a display with a relatively thin thickness. It can be divided into LCD liquid crystal display, PDP plasma display, OLED organic light emitting diode display, FED field emission display, etc. In daily applications, only LCD liquid crystal display is popularized. Many people don't know what a CRT monitor is, and what are the differences between a CRT monitor and a liquid crystal monitor? The editor organizes some relevant information as follows: .
What is a crt monitor?
The scientific name of the CRT display is "Cathode Ray Tube", which is a display that uses a cathode ray tube (Cathode Ray Tube). It mainly consists of five parts: Electron Gun, Deflection Coils, Shadow Mask, High Voltage Graphite Electrode and Phosphor Coating and Glass Housing. It is one of the displays with a wide range of applications. CRT flat-screen displays have large viewing angles, high color reproduction without dead pixels, uniform chromaticity, adjustable multi-resolution modes, and extremely short response time. LCD displays are difficult to surpass. Advantages, and the price is cheaper.
What is an LCD display?
Liquid crystal display, or LCD (Liquid Crystal Display), is a flat ultra-thin display device, which consists of a certain number of color or black and white pixels, placed in front of a light source or a reflective surface. Liquid crystal displays have low power consumption, so they are favored by engineers and are suitable for electronic devices that run on batteries. Its main principle is to stimulate the liquid crystal molecules to generate dots, lines and surfaces with the back light tube to form a picture.
dot pitch
The so-called dot pitch refers to the distance between two phosphors with similar colors in the same pixel. The screen is composed of many pixels, and each pixel is composed of three phosphors of red, green and blue. Because the pixels are next to each other, the distance between the phosphors of the same color in the adjacent pixels is the dot pitch. . At present, the dot pitch of CRT displays is mostly 0.22-0.26 mm, while LCD is mostly 0.297-0.32 mm due to its different technology from CRT.
refresh rate
For the CRT, the graphic image on the screen is composed of fluorescent dots that emit light due to the electron beam hitting. Since the fluorescent powder in the picture tube is hit by the electron beam for a short time, the electron beam must be continuously Hit the phosphor to make it glow continuously. The electron gun starts from the *** line in the upper left corner of the screen (the number of lines is determined by the resolution of the display at that time, for example, under 800X600 resolution, the electron gun will scan 600 lines), scan line by line from left to right, ** line After scanning, start from the left end of the second line to the right end of the second line, and then start from the upper left of the screen until the entire screen is scanned. At this time, a refresh of the screen is completed, and the cycle begins . In this way, we can understand why the higher the resolution of the display, the lower the refresh rate maximum value it can achieve. Generally speaking, the refresh rate of the screen must be above 75HZ, so that the human eye cannot easily feel the flicker of the screen. The refresh rate of the CRT display is determined by its line frequency and the resolution at that time. The higher the line frequency, the same-resolution. The higher the refresh rate, the higher the refresh rate; and the higher the resolution, the lower the refresh rate it can achieve when the line frequency is constant.
For LCD, there is no problem of refresh rate, it does not need to be refreshed at all. Because each pixel in the LCD is continuously emitting light until the voltage that does not emit light changes and is sent to the controller, the LCD will not have the flickering phenomenon caused by "continuous charging and discharging".
visible area
The viewing area refers to the area of the screen that can be used to display images in practical applications. Because the size of the CRT monitor is actually the size of its picture tube, the part that can be used to display the image cannot reach this size at all, because the frame of the picture tube occupies a part of the space. Generally speaking, the viewing area of a 17-inch CRT monitor is about 15.8-16 inches, while the viewing area of a 15-inch monitor is only about 13.8 inches. But for LCD, the nominal size is basically the size of the viewing area, and the space occupied by the frame is very small. The viewing area of a 15-inch LCD is about 14.9 inches, which is why the LCD looks larger than the same size. The reason why the CRT is bigger.
reaction speed
The time unit for measuring the response speed is milliseconds (ms), which refers to the time required for a pixel to change from light to dark and from dark to two. The smaller the value, the better, the smaller the value, the faster the reaction speed. At present, the response speed of mainstream LCDs is more than 25ms, and it does not matter much in general commercial purposes (such as word processing or text processing), because such uses do not need to care too much about the response time of LCD. And if it is used to play games and watch full-screen high-speed dynamic images such as VCD/DVD, the response time is particularly important. To give a simple example, the vast majority of LCD monitors on the market will have varying degrees of smearing when playing QUAKE3, especially when the picture is updated at high speed. The CRT does not have this problem at all, because the response time of the CRT is only 1ms, and there is absolutely no tailing phenomenon.
display effect
Let's talk about CRT first. At present, most of the household-grade CRTs have problems in focusing, convergence, and breathing effects to varying degrees, which are inseparable from the technical process of the manufacturer. If the relevant control circuit designed by the manufacturer is not advanced enough, the problems mentioned above are prone to occur. This is also the reason why the monitors produced by SONY are also different from the monitors produced by some other manufacturers. The LCD has no problems with focusing at all, because it does not need focusing at all. However, problems such as linear and non-linear distortion, LCD may also appear, but CRT is more likely to appear.
