Analyze the composition and working principle of DLP big screen splicing system

The large-screen splicing display system has been widely used in various fields as a modern video-visual tool, such as large-scale post and telecommunications systems, public security command and control, traffic management command, various production scheduling, and power sector. The large-screen display video wall can display signals from various signal sources such as RGB, Video, and computer networks in a centralized manner to meet the needs of users to display various shared information and comprehensive information in large areas. In short, the departments that need panoramic browsing and unified command should choose a large-screen splicing display system.

The DLP digital light processing technology used in large-screen projection wall technology integrates this technology with computer systems, automated monitoring and command systems, network systems, information management systems, and remote video conferencing systems. It is highly automated and high-performance. Videoconferencing and information monitoring system.

Although the big screen is very common in daily life nowadays, for many people, the big screen splicing technology is still unfamiliar. What charm does DLP have made it gradually accepted by people? This article will take Tsinghua Unisplendour's DLP large-screen splicing system as an example to take you into the world of DLP, let us unveil its "mysterious veil."

1 system works 1.1 DMD technology Digital Micromirror Device (DMDTM) is the basis of DLP, DLP projector other elements include a light source, a color filter system, a cooling system, lighting and projection optics.

The DMD can be simply described as a semiconductor optical switch. Thousands of tiny square lenses are built on the hinge structure above the static random access memory to form a DMD. Each lens can turn off one pixel of light. The hinge structure allows the lens to tilt between two states. +12 degrees is "on" and -12 degrees is "off". When the lens is not working, they are in a 0 degree "parking" state.

Each tiny precision mirror is like a “group plate” of a personal worker, but these micromirrors will flip at a certain frequency at a high speed according to the corresponding control signal, so that with the help of the visual persistence phenomenon, they will come from the light source. The light is reflected in the human visual system as graphic pixels with rich levels of color.

1.2 Monolithic DLP System In a single DMD projection system, a dichroic wheel is used to generate a full-color projected image. The color separation wheel consists of a red, green, and blue filter system that rotates at a frequency of 60 Hz and provides 180 color fields per second. In this structure, DLP works in sequential color mode.

The input signal is converted to RGB data. The data is written into the DMD SRAM in sequence. The white light source is focused on the dichroic wheel through the focusing lens, passes through the dichroic wheel, and then is imaged on the surface of the DMD. When the color separation wheel rotates, red, green, and blue light sequentially strike the DMD. The color separation wheel and the video image are in sequence, so when red light strikes the DMD, the lens tilts to “on” according to the position and intensity at which the red information should be displayed, and the green and blue light and video signals work as well. The human visual system focuses on red, green, and blue information and sees a full-color image. Through the projection lens, the image formed on the surface of the DMD can be projected onto a large screen.

Because the DMD has a switching speed of less than 20 microseconds, an 8-bit/color gray scale (256 grayscales) can be implemented with a single DMD system. This gives 256 shades of gray for each primary color, or a combination of 256 cubes of 3 colors.

2 System Structure The overall architecture of the Tsinghua Unisplendour large-screen system consists of a 60-inch digital projection unit, an image mosaic controller and control software.

Physically, the entire combined display consists of modular, standardized, and integrated precision aluminum alloy projection boxes. Each enclosed projection box body includes a DLP projector and a black multi-layer composite optical glass screen, and the projector core and the screen display images in one-time reflection rear projection.

2.1 Projection Core The projector core, as the core display unit of the projection wall display system, is equipped with a 0.7-inch DMD-DDR chip that can be used for all-weather digital display applications.

2.2 Black multi-layer composite optical glass screen As the direct medium for the viewer, the final imaging image generation layer, composite glass screen can provide bright, high-contrast, high-resolution images for the professional application of the projection display.

2.3 Graphics splicing processor In the large-screen projection system, the graphic splicing controller is the core of signal processing, which largely determines the display effect, display quality, operation flexibility, and system reliability of the entire system. The graphic splicing controller independently developed by Tsinghua Unisplendour can access multiple RGB signals (computers) and multiple real-time video images and network computer images. All different types of signals can be mixed and displayed in any position, zooming, dragging, splicing, and full screen display with open window or hard splicing. The network and RGB signals can be superimposed with the video signal without being limited by the physical screen. Realize full dynamic real-time.

The large-screen splicing market is a very technical industry. The large-screen projection system has good graphic and image display functions, and the operation is easy to understand. It also has features such as vivid color images, clear and sharp images, stable equipment operation, and maintenance-free features. The above advantages make DLP-based projectors become mainstream models of large-screen projection systems, and DLP large screens will surely gain wider application in all walks of life.