Projectors are divided into two technologies.
LCD (Liquid Crystal Display) projector.
Liquid crystal display technology is one of the leading technologies in the projector market at present. Liquid crystals include active liquid crystals and inactive liquid crystals. Inactive liquid crystals reflect light and are generally used in notebook computers and movie projectors. Active liquid crystal has light transmittance, and it is made into LCD panel for projector.
LCD projectors are divided into LCD panels and LCD light valves. Most of our common projectors are LCD flat panel projectors.
First, the LCD projector
The liquid crystal projector uses the electro-optical effect of the liquid crystal to control the transmittance and reflectivity of the liquid crystal unit through the circuit, thus producing beautiful images with different gray levels and as many as16.7 million colors. The light source of LCD projector is a special high-power bulb, and its luminous energy is much higher than that of CRT projector using fluorescence, so the brightness and color saturation of LCD projector are higher than that of CRT projector.
The size of LCD panel determines the structure and total volume of projector. The smaller the area of the LCD panel, the smaller the optical system of the projector, thus making the projector smaller.
At present, the panel sizes of LCD projectors on the market are mostly 1.32 inch (1 inch =2.54cm), 0.9 inch and 0.7 inch, which can support the physical resolution of SVGA and XGA. New LCD panels, such as 0.79-inch and 0.99-inch panels with high aperture ratio, have also begun to appear.
At present, there are only two suppliers of high-temperature LCD projection LCD panels in Japan: Epson and Sony.
The advantage of LCD projector is excellent color performance and high brightness, but the disadvantage is that the light efficiency is affected to some extent because of the projection mode, and there is pixel phenomenon in the projected image.
LCD flat panel projectors can be divided into single-chip projectors and three-chip projectors. Modern LCD panel projectors mostly use three-piece LCD panels (Figure 1). The three-piece LCD projector uses three LCD panels: red, green and blue, which are used as the control layers of red, green and blue light respectively.
The three-piece LCD projector has higher image quality and brightness than the single-piece LCD projector. The LCD projector has the advantages of small size, light weight, simple manufacturing process, high brightness and contrast, and moderate resolution. It is the most widely used projector in the market at present.
DLP (digital light processor) digital projector
DLP technology is a patented technology of TI (Texas Instruments). The projector based on DLP display technology first appeared in 1996. Its imaging device is DMD (digital micromirror device). DMD chip contains thousands of micromirrors, each mirror represents a pixel, and the on or off state represents the brightness of the pixel in the image. The light beam is projected onto the DMD through the high-speed rotating color wheel (color separation device), and then onto the big screen through the optical lens. At present, DLP technology is patented by TI, and TI is also the only supplier of DMD chips.
First, the technical advantages of DLP projectors
The first is digital advantage: the adoption of digital technology makes the contrast, gray scale (256- 1024), color (2563- 10243), signal-to-noise ratio and stable image quality of the image excellent.
Secondly, the advantage of reflection: due to the application of reflective DMD devices, the distance between micromirrors that constitute DLP image pixels is very small, which makes the light transmission efficiency of imaging devices reach more than 85%. The generated image is very bright and has high definition.
B, DLP projector can be divided into:
Single-chip microcomputer: The advantages of single-chip DLP projector are high light efficiency, high contrast and clear image, especially in black and white graphics and text. At the same time, the single-chip DLP projector can be small and light, but the disadvantage is that the color performance is not realistic and natural.
Three-chip machine: DLP projector made of three DMD chips has higher brightness and richer colors, and the brightness can be as high as 10000ANSI lumens, which is mostly used in special occasions such as digital cinemas.
At present, projectors on the market mainly include LCD technology and DLP technology. Most Japanese manufacturers adopt LCD technology, while European and American manufacturers can adopt LCD and DLP technology. The competition between LCD and DLP is fierce. There is no clear answer about whose product and technology are better, but it can be said for sure that the projector using DLP has higher picture contrast and more compact optical system, so it has advantages in volume and weight. And LCD is very strong in brightness uniformity, color and detail. The two technologies have their own characteristics and are inseparable. They will exist for a long time to come. Unless one party makes a breakthrough in technology or market strategy, it is expected to break this balance and occupy a dominant position.
1, main performance index of projector
A, brightness (lumen)
At present, the brightness unit of projector is ANSI lumens, which is a method for measuring projector luminous flux developed by American National Standardization Association. The method of ANSI brightness test is to debug and set the projector according to ANSI regulations, then select nine places with the same area and size in the center of the screen, measure their brightness values, and then take the average value to get ANSI lumen brightness values.
The measurement environment is as follows:
(1) Distance between projector and screen: 2.4m
(2) The screen is 60 inches.
(3) Measure the brightness of nine points on the projection screen with a light measuring pen.
(4) Find the average of 9 luminances, which is ANSI lumens.
According to the different brightness, the current general projector applications can be divided into:
A, 1000- 1800ANSI (business application, entertainment application)
B, 1800-3000ANSI (educational application)
C. Above C.3000ANSI (professional application)
B. Solve
Projector resolution refers to the number of pixels of the image projected by the projector. Indicators are divided into nominal resolution and maximum input resolution.
Nominal resolution refers to the actual resolution of the image projected by the projector, also known as physical resolution or actual resolution.
The maximum input resolution means that the projector can receive a resolution larger than the physical resolution and project the signal through the compression algorithm.
According to the different resolutions, the current applications of general projectors can be divided into:
a、SVGA (800× 600)
B XGA (1024× 768) "Educational application, business application and entertainment application"
C, SXGA( 1024×768 or above)
C. weight of the projector
According to different weights, projectors can generally be divided into ultra-portable projectors, portable projectors, portable projectors and fixed projectors.
According to the different weights, the current applications of general projectors can be divided into:
A. Ultra-portable projector (less than 2kg)
B, portable projector (2-4 kg)
C, portable, fixed projector (more than 4kg)
D, comparison
The most basic form of contrast is the ratio of bright areas to dark areas. The greater the ratio, the more layers from black to white, and the richer the color performance.
E. consistency
The picture projected by any projector will have different brightness in the central area and the four corners. Uniformity is the ratio of edge brightness to center brightness. The higher the uniformity, the better the consistency of the picture.
F, bulb life and power
At present, projectors generally use metal halogen bulbs, UHP bulbs and UHE bulbs.
Metal halogen bulbs have the advantage of low price and the disadvantage of short half-life. Generally use 1000 hours or so, the brightness will be reduced to about half of the original brightness. Moreover, because of its high calorific value, it requires a high cooling system of the projector and is not suitable for long-term (more than 4 hours) projection.
The advantage of UHP bulb is its long life, which can be used normally for more than 2000 hours, and the brightness attenuation is very small, so it is customarily called cold light source.
UHE bulb is characterized by low power consumption and long life, and it is an ideal cold light source.
At present, there are few manufacturers providing light bulbs for projectors in the world, and the well-known manufacturers in the market are Philips, Osram and so on.
Since I don't know what kind of use you will have when you buy the projector, I will introduce it to you as a business use (unfamiliar at home). I'll give you several mainstream models with different technologies (Sony/Epson doesn't have DLP).
Sony CX63 3000ANSI1024 * 768 3.8kg LCD screen.
Epson EMP-8213000ansi1024 * 768 4.0kg LCD.
Toshiba TLP-x2500 2500ansi1024 * 768 2.8kg LCD.
TLP X 3000 3000 ANSI1024 * 768 2.8kg LCD.
NEC lt 380+3000 ansi 1024 * 768 3.5kg LCD
Lt 695+2500ansi1024 * 768 2.9kg LCD.
Sharp xr-2280x3200ansi1024 * 768 3.9kg DLP
XR-8 180 x 2500 ansi 1024 * 768 3.9kg DLP
BenQ mp725x2500ansi1024 * 768 2.9kg DLP
MP 775 3200 ansi 1024 * 768 2.9kg DLP
The contrast of DLP projection is 2000: 1, and that of LCD is about 600: 1. Sorry I didn't write the price. The LCD is within 13000, and the DLP is within 9000. You'd better go to the market and see the effect.