【 Weak current College 】 homemade projector utility maintenance technology information (1)---Power By 【 China power house network 】

First, the basics of the projector
In order to repair the projector must be aware of some of the most basic knowledge, including CRT, LCD, DLP projection technology works and the meaning of the parameters so that maintenance personnel have a more comprehensive understanding. LCOS projector is not a mainstream products and is not covered.
1, CRT projector works
CRT projector and three guns cathode ray tube projectors, it mainly consists of three CRT tube, electron gun deflection coil and tube Panel. In order to make the CRT tube display images on the screen, the CRT projector to signal input signal decomposition to R (red), G (green), B (blue) three CRT tube screens, projection to gather in large screen displays a color image.
CRT projector according to the CRT tubes in different diameters can be divided into: 7 inch tube, 8-inch pipe, 9-inch tube projectors. CRT projector display image rich colors, restore good, has a wealth of geometric distortion adjustment capability, the disadvantage is the low brightness, manipulate complex, bulky, environmental requirements for the installation.
CRT projector of two specific performance indicators:
1. convergence performance
Convergence is the R, G, B 3 colors on the screen in a fully coincide with the CRT projector, convergence control appears especially important, because it has an R, G, B three CRT tube, the parallel installation in brackets, in order to achieve the image fully convergent, must have the image of various distortion correction. Machine location changes, and even a small change, convergence has to resize, so on a converging adjustment request is fully functional and convenient. Convergence have static and dynamic, dynamic convergence with tilt, bow, amplitude, linear, trapezoid, Pincushion, and other functions, each of these features are available in horizontal and vertical two directions. In addition, may also conduct non-linear balance correction.
2. focus on performance
CRT'sfocus method can be divided into power focus and physical focus. We know that the graphics of smallest unit is pixels, pixel smaller graphics resolution is higher, but the CRT tube, a minimum pixel is determined by focusing on performance, the so-called recordable address resolution, which is the minimum number of pixels.
While the focus is divided into static electricity focus, magnetic and electromagnetic composite focus focus. With more advanced electromagnetic composite focus, its advantages are good (but high-luminance conditions would defocus), and focus on high precision, you can focus on regional focus, focus, the corners of the edge so that you can do every point on the screen is very clear. Its working principle figure 1:
2. LCD projector works
LCD projector, LCD projector, the core components for the LCD Panel, a passive glow and Imaging. The so-called LCD i.e. between between liquid and solid substances, which itself does not glow, work material governed by the temperature influence is very big, its working temperature is-55 ° c to 77 degrees centigrade. Photoelectric effect using LCD projectors, that is, the arrangement of liquid crystal molecules in the electric field changes, affecting its LCD unit of transmittance or reflectivity, thus affecting its optical materials, produced with different grayscale and color images. LCD projector is divided into single-chip LCD and three slices of LCD machine, a passive way, using the external projection of the light metal halogen lamp and UHP, UHE (cold light), exposure and display images, general import single-chip projector uses liquid crystal panels for special LCD panels, and domestic low end projector with LCD panels are used to produce LCD monitor of second-hand LCD, used as a projection of the backlight can be withdrawn. This LCD is true colour TFT and pseudo color STN, making the best choice when the projector TFT true color playback screen guarantees, because the true color display image colorful, nature and sense of depth.
Three LCD panels projector principle is the optical system to light through the formation of the three RGB light beam splitter, exposure to RGB tricolor LCD panels, signal source through the ADC, and then added to the liquid crystal panel, through the control panel unit opened, closed, so as to control the on/off light path, RGB light last in a cross-directional prisms in convergence, by projection lens projection on screen color image formation. At present three LCD machine is the main LCD machine models, with the development of science and technology, three slices of LCD panels dimensions are smaller, smallest 0.5 inches, the total volume is more compact. And single-crystal machine small size, light weight, operation, easy to carry, lower prices, but his short life of light source, color is not uniform, resolution is low, so the current import professional single-chip LCD projector is fading out of the market, replaced by domestic low end projector market.
Import single-chip LCD projector works as in Figure 2:

Triple LCD projector works as in Figure 3: