Differences among LCD, PDP and DLP splicing
Differences between spliced screens1. Principle of plasma
PDP means Plasma Display Panel. PDP is a flash technology using gas discharge, and its principle is very similar to that of fluorescent lamps. It chooses plasma tube as light-emitting element. Each plasma tube on the screen corresponds to a pixel. The screen uses glass as the base plate, the base plate is at a certain distance, and the left and the right are sealed by air tightness to form a discharge space. The discharge space is filled with neon, xenon and other mixed inert gases as the task medium. Metal oxide conductive film is coated on the inner face of two glass substrates as the task medium. Encourage the electrode. When the voltage is applied to the electrode, the mixture gas in the discharge space will produce a plasma discharge phenomenon, also known as plasma effect. Ultraviolet radiation is emitted by gas plasma discharge. Ultraviolet radiation excites a fluorescent screen coated with red, green and blue phosphors. The fluorescent screen emits visible light and flashes images. When each color unit finishes 256 levels of gray level and then stops mixing, it completes the colorful flashing. Its technical principle is that, because the plasma tubes emitted in PDP are dispersed in the stereo on average, the base and edge of the flash image are totally different, and the scene will not be distorted. The real pure stereo is completed without any image distortion. Because there is no movement of electron beam in the flash process and no need to rely on electromagnetic field, the external electromagnetic field will not disturb it and has good environmental compliance. PDP is a self-luminescent flash technology, which does not require a scene light source, and therefore has no visual angle and luminance average performance. The scheme of three-color phosphors sharing the same plasma tube also prevents aggregation and aggregation, and can complete very clear images. High voltage, high power consumption, high energy consumption and shortage of life. The brightness of the screen will decrease by half after 5000-10000 hours, and it is difficult to perform normal tasks above 2500 meters above sea level.
2. DLP Principle
DLP is the abbreviation of Digital Lighting Progress. It means digital optical processing, that is to say, this technology first digitally processes the abstract signal, and then projectes the light. It is based on the digital micromirror device-DMD developed by Deyi Company to complete the ultimate link of flashing digital visual information, while DMD is the abbreviation of Digital Micromirror Device, literally meaning digital micromirror element. This refers to the base of DLP technology fragmentation-the digital micromirror chip selected by the heart of optical engine. It is in the standard semiconductor manufacturing process of CMOS, plus A device that can adjust the rotating structure of the reflector. More specifically, DLP projection technology uses digital micromirror chip (DMD) as the primary key component to complete the digital optical processing process. The principle is that the light source is averaged by an integrator. After a color Wheel with three primary colors, the light is divided into R, G and B colors, and then the color is imaged by a lens on a DMD. By means of synchronous signals, the electrical signals of Digital Rotating lenses are transformed into gray scale, and the color is displayed by coordinating R, G and B colors. Finally, the image is projected through the lens.
From the technical principle of DLP, it has the following disadvantages:
1. Music disadvantage: DLP inherent digital nature can make noise disappear, because DLP has the ability to complete the final link of digital video underlying structure, and provides a way to develop digital video communication environment. DLP technology provides an achievable projection method of flash digital signal, thus completing the whole digital underlying structure, with the least signal music.
2. Accurate gray level: Its digital nature can obtain precise image quality and color reproduction with accurate digital gray level.
3. Reflection Disadvantage: Because DMD is a reflection device, it has over 60% optical power, making DLP piecemeal flash more power. This power is the function of reflectivity, filling factor, diffraction power and the onset of the practice lens "on".
4. Seamless image disadvantage: 90% of the pixel/lens area can ineffectively reflect light and form a projection image. All arrays adhere to the pixel specification and the average distance, and do not depend on resolution. The higher the DMD filling factor, the higher the visible resolution. In this way, with progressive scanning, a more realistic and natural projection image can be invented than the ordinary projector.
5. Reliability: DMD has passed all standard semiconductor qualification tests. It has also been checked by imitating DMD practice operating environment conditions, including thermal shock, temperature cycle, moisture resistance, mechanical shock, oscillation and deceleration experiments. According to thousands of hours of life and environmental tests, DMD and DLP fragments show inherent reliability.
LCD liquid crystal flasher is abbreviated as LCD. The structure of LCD is to place liquid crystals beside two parallel pieces of glass. There are many vertical and slim wires on the base of the two pieces of glass. Through electrification or not, the rod crystal molecule can be controlled to change its direction, and the light can be refracted to produce a picture. LCD consists of two glass panels, about 1 mm thick, with an average distance of 5 microns including liquid crystal data. Because the LCD data itself does not emit light, there are lamp tubes as light source in the middle of the flash screen, and there is a backlight plate (or even light plate) and reflective film in the LCD flash screen. The backlight plate is composed of fluorescent substances, which can emit light. Its function is to provide an average light source for the scene. The light declared by the backlight plate passes through the first polarization filter layer and enters the liquid crystal layer including countless liquid crystal droplets. Droplets in the liquid crystal layer are included in the fine cell structure, one or more cells constitute a pixel on the screen. There is a transparent electrode between the glass plate and the liquid crystal data. The electrodes are divided into rows and rows. The optical rotation of the liquid crystal is changed by changing the voltage. The function of the liquid crystal data is similar to that of a small light valve. There are some control circuits and some drive circuits around the LCD data. When an electric field is applied to the electrodes in the LCD, the liquid crystal molecules distort, stopping the regular refraction of light passing through them, and then flashing on the screen after filtering through the second filter layer. LCD splicing (LCD splicing) is a new splicing technology developed in recent years after DLP splicing and PDP splicing. LCD splicing wall has the advantages of low power consumption, light weight, long life (50,000 hours of normal tasks), no radiation, average brightness of the picture, etc. But its biggest defect is that it can not achieve seamless splicing, and demands very precise task users for flash pictures. For one thing, it's a little bit frustrated. Since the LCD screen will have a border when it is manufactured, the LCD splicing will show a border (seam). For example, the border of a single 21-inch LCD screen is usually 6-10 mm, and the seam between two LCD splicing screens is 12-20 mm. In order to increase the gap of LCD splicing, there are several ways in the industry nowadays. One is narrow splicing, the other is micro-splicing. Micro-splicing means that the manufacturer dismantles the shell of the LCD screen bought back and stops splicing between glass and glass. However, this method is risky. Assuming that the poor splicing of the LCD screen will damage the quality of all LCD screens, nowadays there are a large number of international LCD screens. Manufacturers use this approach.
In addition, after 2005, Samsung launched the joint public LCD screen - DID LCD screen. The DID LCD screen is specially designed for splicing, and its border is very small when it is manufactured. Three main technical features of PDP plasma, DLP and LCD are as follows:
DLP splicing screen Advantages: large specification, small mosaic, slow attenuation of digital flash brightness, small gap of pixels, fine image, suitable for long time flash computer and static image DLP mosaic Defects: Low brightness than plasma. More splices will show uneven brightness, large occupancy space, high power consumption and high maintenance cost in the early stage. PDP splicing
Advantages: high single-screen average, high brightness, high contrast and fine image of PDP stitching defects: large pixel gaps, simple burning of flash computer images or static images, fast brightness attenuation and unable to travel, low reliability, high consumption of electrodes, LCD liquid crystal stitching benefits: low power consumption, light weight, easy equipment, stop arbitrary stitching, longevity LCD LCD splicing with long (normal task more than 50,000 hours). No radiation, average brightness, good picture quality and low maintenance cost Defects: It can not achieve seamless stitching (today, the narrowest has been achieved in the middle of 7mm and it can be negligent)
Nowadays, the most rare LCD splicing wall specifications are 19 inches, 20 inches, 40 inches and 46 inches. It can splice freely according to customers'needs. It can reach the maximum of 10X10 splicing. It uses backlight to emit light and has a life of up to 50,000 hours. Secondly, the LCD has small point spacing, and its physical resolution can easily reach the HD specification. Otherwise, the LCD screen has low power consumption, low calorific value, and the power of more than 40 inches LCD screen is only 150 W. It only needs about 1/4 of the plasma, and the task is stable and the maintenance cost is low. With the development of liquid crystal technology from time to time, LCD splicing screen has been widely used in various tasks.