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With the progress of science and technology and the development of society, people are no longer satisfied with the visible area of LCD, but develop projection technology that can display a larger area. Since the development of projection technology, a total of three common technologies have been derived, they are: DLP projection technology, 3LCD projection technology and CRT projection technology. Let's take a look at how CRT projection works.
Introduction
The CRT (Cathode Ray Tube, a Cathode Ray Tube) can be described as a "founder" projection technology. The CRT projector will decompose the input signal source into the fluorescent screen of R (red), G (green) and B (blue) CRT tubes. Under the action of high pressure, the luminous signal will be amplified and converged to display the color image on the big screen.
Optical system and CRT tube to form a projection tube, usually referred to as the three gun projector is composed of three projection tube projector. The CRT projector displays images with rich color and good performance, and has rich ability to adjust geometric distortion. The disadvantages are low brightness, complex operation, large volume, high requirements for the installation environment.
However, there are two performance metrics specific to CRT projectors that are worth noting.
Performance
1. Convergence
Convergence refers to the overlap of red, green and blue colors on the screen.
For the CRT projector, convergence control is particularly important, because it has RGB three kinds of CRT tube, parallel installation of the ground shelf, in order to achieve full convergence of the image, the image must be able to correct all kinds of distortion. The change of machine position, convergence also need to be adjusted, so the convergence requirements, one is full function, two is convenient and fast. Convergence has static convergence and dynamic convergence, in which dynamic convergence has tilt, arch, amplitude, linear, trapezoid, pillow shape and other functions, each function can be adjusted in both horizontal and vertical directions. In addition, nonlinear balance, trapezoidal balance, pillow balance can be adjusted.
2. Focusing performance of CRT tube
We know that the smallest unit of a graph is a pixel. The smaller the pixel, the higher the graphic resolution. In a CRT tube, the minimum pixels are determined by the focusing performance, and the addressable resolution is the number of minimum pixels.
Focusing mechanism of CRT tubes with electrostatic focus, magnetic and electromagnetic focusing on three, in which electromagnetic composite is focused on the more advanced, its advantage is the focus performance is good, especially under the condition of high brightness will defocusing, and focus on high precision, can undertake focus areas, focus of edge, focusing on the four corners, which can be done on each point is very clear.
Summary
The advantages of CRT technology are high resolution, good contrast, good color saturation, strong signal compatibility and mature technology. The disadvantage of CRT projection product is that the luminescence of phosphor is then projected onto the screen for imaging. When the number of effective scanning electrons increases to the saturation state, the number of effective scanning electrons is increased, and the luminescence amount of phosphor does not increase much. From the perspective of the orthographic projection market, CRT projection has retreated from the mainstream market, and the orthographic projection market is mainly occupied by liquid crystal projectors. As far as the market share of back projection is concerned, CRT's back projection is still in the dominant position, and will continue to occupy a high market share in the next year or two.
Introduction
The CRT (Cathode Ray Tube, a Cathode Ray Tube) can be described as a "founder" projection technology. The CRT projector will decompose the input signal source into the fluorescent screen of R (red), G (green) and B (blue) CRT tubes. Under the action of high pressure, the luminous signal will be amplified and converged to display the color image on the big screen.
Optical system and CRT tube to form a projection tube, usually referred to as the three gun projector is composed of three projection tube projector. The CRT projector displays images with rich color and good performance, and has rich ability to adjust geometric distortion. The disadvantages are low brightness, complex operation, large volume, high requirements for the installation environment.
However, there are two performance metrics specific to CRT projectors that are worth noting.
Performance
1. Convergence
Convergence refers to the overlap of red, green and blue colors on the screen.
For the CRT projector, convergence control is particularly important, because it has RGB three kinds of CRT tube, parallel installation of the ground shelf, in order to achieve full convergence of the image, the image must be able to correct all kinds of distortion. The change of machine position, convergence also need to be adjusted, so the convergence requirements, one is full function, two is convenient and fast. Convergence has static convergence and dynamic convergence, in which dynamic convergence has tilt, arch, amplitude, linear, trapezoid, pillow shape and other functions, each function can be adjusted in both horizontal and vertical directions. In addition, nonlinear balance, trapezoidal balance, pillow balance can be adjusted.
2. Focusing performance of CRT tube
We know that the smallest unit of a graph is a pixel. The smaller the pixel, the higher the graphic resolution. In a CRT tube, the minimum pixels are determined by the focusing performance, and the addressable resolution is the number of minimum pixels.
Focusing mechanism of CRT tubes with electrostatic focus, magnetic and electromagnetic focusing on three, in which electromagnetic composite is focused on the more advanced, its advantage is the focus performance is good, especially under the condition of high brightness will defocusing, and focus on high precision, can undertake focus areas, focus of edge, focusing on the four corners, which can be done on each point is very clear.
Summary
The advantages of CRT technology are high resolution, good contrast, good color saturation, strong signal compatibility and mature technology. The disadvantage of CRT projection product is that the luminescence of phosphor is then projected onto the screen for imaging. When the number of effective scanning electrons increases to the saturation state, the number of effective scanning electrons is increased, and the luminescence amount of phosphor does not increase much. From the perspective of the orthographic projection market, CRT projection has retreated from the mainstream market, and the orthographic projection market is mainly occupied by liquid crystal projectors. As far as the market share of back projection is concerned, CRT's back projection is still in the dominant position, and will continue to occupy a high market share in the next year or two.
