Engineering projectors have larger projection areas, longer distances, and high brightness, and generally support multi-bulb mode, which can better cope with large and changeable installation environments, and are very suitable for education, media, and government fields.
In projection display equipment, projection display is divided into front projection (Front Projection) and rear projection (Rear Projection) according to its projection method. Projectors are equipment that displays front projection. According to display devices, there are usually LCD projectors, DLP projectors and LCOS projectors both use microdisplay chips as the main components of imaging.
1. Motorized lens, that is, lens shift technology. Because in the actual project, the lens of ordinary business projectors cannot be moved, and the actual environment may require that the position of our projector cannot be moved, but it is required that the lens can be moved up, down, left, and right to meet the projection requirements.
2. Double bulbs, engineering projectors are equipped with at least 2 projector bulbs. Some projectors have 4 bulbs, and high-end ones even have 8 bulbs. The significance of configuring dual bulbs is that when a projector bulb is broken, the projector will not fail to work unless it is broken at the same time. So when one light bulb is broken, the remaining light bulbs can continue to work to satisfy engineering use.
3. The network control function requires the projector to be able to pass the network. Project projectors need to be able to monitor the running status of the machine through the RJ45 network control port, and switch the projector on and off
4. The lens can be replaced: that is, the lens of the projector can be replaced with a long focal lens or a short focal lens as needed.
CRT (Cathode Ray Tube) is a cathode ray tube. It is a widely used display technology. The CRT projector decomposes the input signal source to the three CRT tube fluorescent screens of R (red), G (green) and B (blue). Under the action of high voltage, the luminous signal is amplified and converged to display a color image on the large screen.
It has two features worth noting: one is convergence performance: for CRT projectors, convergence control is particularly important, because it has three types of RGB CRT tubes, which are installed in parallel on the ground bracket. If you want to achieve complete convergence of the image, Various distortions of the image must be corrected. As the position of the machine changes, the convergence must be re-adjusted. Therefore, the requirements for convergence are one of full functions, and the other is convenient and fast.
Convergence has static convergence and dynamic convergence. Dynamic convergence has functions such as tilt, bow, amplitude, linear, trapezoid, and pincushion. Each function can be adjusted in both horizontal and vertical directions. In addition, non-linear balance, trapezoidal balance, and pincushion balance can also be adjusted. The second is the focusing performance of the CRT tube: the focusing mechanism of the CRT tube includes electrostatic focusing, magnetic focusing and electromagnetic composite focusing. Among them, the electromagnetic composite focusing is more advanced, and its advantage is good focusing performance, especially defocusing under high brightness conditions. , And the focusing accuracy is high, it can focus on sub-regions, edge focus, and four corners, so that every point on the screen can be very clear. CRT projectors display images with rich colors, good reproducibility, and rich geometric distortion adjustment capabilities; the disadvantages are low brightness, complex operations, bulky, and high requirements for the installation environment.
LCD (Liquid Crystal Display) projectors are divided into liquid crystal panel projectors and liquid crystal light valve projectors. Liquid crystal is a substance between liquid and solid. It does not emit light. Its working properties are greatly affected by temperature. Its working temperature is -55oC~+77oC. The projector uses the photoelectric effect of liquid crystals, that is, the arrangement of liquid crystal molecules changes under the action of an electric field, which affects the transmittance or reflectivity of its liquid crystal cells, thereby affecting its optical properties, and producing images with different gray levels and colors. According to the number of LCD panels, LCD projectors are divided into three-chip machines and single-chip microcomputers. The principle of three-chip LCD panel projectors is that the optical system passes strong light through a beam splitter to form three RGB beams, which are respectively transmitted through the RGB three-color liquid crystal panel; The source undergoes AD conversion, modulated and added to the liquid crystal panel. By controlling the opening and closing of the liquid crystal unit, the on and off of the light path is controlled. Finally, the RGB light is converged in the prism and is projected on the screen by the projection lens to form a color image. The three-panel projector is the main type of LCD panel projector. LCD single-board projectors are small in size, light in weight, extremely convenient to operate and carry, and relatively inexpensive. But its light source life is short, the color is not uniform enough, and the resolution is low. There are very few single-board projector models.
DLP (Digital Light Processor) digital light processor. The technology of the DLP projector is an all-digital reflective projection technology. Its characteristic is first of all digital advantages. The adoption of digital technology improves the gray level of the image, eliminates image noise, stabilizes the image quality, and makes the digital image very accurate. The second is the reflection advantage. The application of reflective DMD devices greatly improves the total light efficiency of imaging devices, and the uniformity of contrast and brightness is excellent. The DLP projector has high definition, uniform picture, and sharp color. The three-chip projector can achieve high brightness, and it can zoom at will, and the adjustment is very convenient.
D-ILA (Direct-Drive Image Light Amplifier) technology. D-ILA technology shows technical advantages in providing high resolution and high contrast. In 2000, the nominal resolution of D-ILA technology projectors reached S-XGA (1365×1024), and the contrast ratio reached 350:1. The core component of the D-ILA technology, the 3.3cm (1.3 inch) LCD panel, has a nominal resolution of QXGA (2048×1535). The core component of D-ILA technology is a reflective active matrix liquid crystal on silicon panel, which is commonly referred to as a reflective liquid crystal panel, so some people call D-ILA technology a reflective liquid crystal technology. In the D-ILA technology, the liquid crystal panel uses transistors as the switching control unit of the pixel dot liquid crystal on a layer of silicon substrate. The silicon substrate (also called the reflective electrode layer) is located under the liquid crystal layer and is used for various controls of pixel address addressing. The electrode and the insulating layer between the electrodes are located under the silicon substrate, so the entire structure is a 3D arrangement. The optics from the light source cannot penetrate the reflective electrode layer, but is reflected by the reflective electrode layer, avoiding the blocking of light by the various structural layers below. Therefore, the aperture ratio of the liquid crystal panel using D-ILA technology can be up to 93% (the aperture ratio of the DMD in DLP technology is 88%, and the aperture ratio of the liquid crystal panel of the transmissive LCD is 40% to 60%), so D -ILA technology projectors use more efficiently the light source and can achieve higher brightness output.
The sRGB of the projection display system is developed by Microsoft in cooperation with Seiko Epson and Mitsubishi. The purpose is to establish a color management standard that can meet the needs of computers and projection displays, so that the display device can be correctly analyzed without special color information analysis. Show the image file. sRGB eliminates the original differences in color reproduction of different display systems. The RGB colors between different display devices will naturally undergo some changes, so the colors cannot be reproduced correctly after different display devices. Nowadays, as computer-assisted presentation equipment has increasingly become a key tool for market development, correct image and color reproduction have become more important than before. With sRGB technology, users can ensure uniform colors regardless of whether they use CRT equipment to watch, or through projectors that adapt to the sRGB standard.