LED technology is one of the most noteworthy new development directions of projection

After years of technological development and product marketization, the projector products developed using micro -display devices are already quite mature in technology. Projection products can be said to have penetrated into many large-screen display fields such as education, business and even home entertainment. Currently, various specifications and models of front projectors and rear projectors are available on the market. LCD , LCOS and DLP are the three main micro-display projection original technologies. In the ordinary civilian field, their sizes range from about 0.55 inches to 1.3 inches. The digitization, networking and multimedia interconnection of projection display technology have been realized. The core components of projection products include light source lighting system, color separation and combination processing system, projection lens , image signal processing circuit, micro-display devices, etc. In terms of display effect, the current projection products can fully meet the needs of users. Of course, users' expectations for products are endless. Users hope to get more compact and portable projection products that can be easily carried around for application. They also hope that the products have a higher cost-effectiveness. Not only the price of the product, but also the service life of components such as bulbs is also a very important part. After all, the current projection bulbs are expensive. In addition, as the "core" of projection products, the display effect must be guaranteed in the application. Although the new products have made great improvements in the above three major performance improvement requirements, the "bottleneck" is becoming more and more obvious, because this is closely related to the design of the projection optical system. If you want to get better products, you must have newer and more practical technologies and product applications. LED light source technology has been well developed and applied, and it can be said to be one of the most noteworthy new development directions of projection. How is the development of LED light source projectors in the current market? The projection products using LED light sources first appeared in front of the public at the SID annual meeting held in May 2003. They caused a great response with their pocket-sized bodies. However, they were only concept products at that time. What was truly of practical significance was the five companies that simultaneously exhibited pocket projectors with LED light sources at the CES in January 2005. Only then did people begin to truly consider the advantages and disadvantages of LED light source projection products in terms of application. After another year of technical and product development, LED light sources became a prominent highlight at the CES in January 2006, and a large number of LED light source papers were published at the SID symposium in June 2006, marking a new stage in the development of LED . As a result of the attention paid, the performance of LED light sources has been comprehensively improved in the past two years. In terms of core performance, it has better luminous efficiency, greater power , improved luminous angle , and monochromatic luminous performance, thereby improving unit luminous brightness . In addition, the new products have achieved AC and DC dual-use, and improved thermal management. These developments have made projection products using LED light sources more outstanding in application performance, and the performance improvement has also provided a foundation for the market development of products. What are the technical advantages of LED light source projectors? The application of LED light sources, in terms of projectors, has the most important significance in that it has opened up a new path for miniaturization of the fuselage. Since LED light sources are small in size and have many display technology advantages, they are more suitable for the development of compact projectors and even originals, making the user's projection more "portable" and "free". LED is used for projection lighting, which not only increases the lifespan, but also changes the structure of the projector. Since the heat dissipation demand is reduced and the optical path system is shortened, the heat dissipation and noise are better. At present, LED light sources are mainly used in two types of projection products: integrated small projection originals and pocket-sized miniature machines. Integrated small projection originals are not made into independent models. They are mainly integrated with micro display devices such as mobile phones, digital cameras, and laptops. They are battery-powered and can project images about the size of A4 paper or standard letter paper, making it convenient to share the screen with others. Pocket-sized handheld projectors are complete independent models, small and light, and can be easily picked up by one hand. They are easy to carry and can be placed in a briefcase. The future development direction is business applications. It can be used for both AC and DC, and the projection screen can be larger than 17 inches. The screen brightness is 15 to 200 lumens . With the development of technology, the display effect is still improving. What are the projectors using LED light sources on the market? LED light source projection products have gone through several generations of development. From the earliest Mitsubishi and Samsung "pocket" projection products, although the appearance design is impressive, the brightness is not enough to support daily use. The products of EPSON and BenQ that appeared later are more ingenious in design. EPSON products are equipped with two large fans to improve product stability, while BenQ's LED projector is used with its smartphone to shape a business image, but the practicality of these two products is "not flattering", and it is even difficult to see prototypes. The "third generation" of LED projector products, including Mitsubishi's new products, Toshiba's popular promotion products and LG's personalized products, give people very good expectations in terms of real application. Mitsubishi's new LED projection products improve the brightness on the basis of the previous generation and focus on picture demonstration. Toshiba's new product is more "productized". It has been launched in China and its "overall concept" is excellent. The professional backpack equipped with it contains a special projection folding screen, which can be opened for use. The high gain can supplement the projection brightness. Moreover, this backpack is designed to fit a laptop and an LED projector, which is suitable for business people to use on the go . LG's latest LED projector adopts a "chocolate" style design, which also has improved effects and is more suitable for fashionable young people. Technical bottlenecks and development direction of LED light source projectors In general, after several years of development, LED light source projectors have already accumulated certain product performance and technology, and the latest products can also show initially satisfactory pictures. However, LED light source projectors still face the biggest "insurmountable" peak, which is the problem of insufficient brightness. In actual use, it is still difficult to replace bulb-type products. This is also the main reason why it is currently in a "difficult period" of development. The important beam expansion theory in the design of lighting systems can ensure the full utilization of light energy through calculation. Once the display components and lenses are determined, the matching LED light source can be selected quickly. After compromise and adjustment in the design process, the parameters can be confirmed. The brightness of projection products is most directly determined by the brightness of the LED. At present, the "maximum brightness" still cannot meet the application conditions, which is undoubtedly the biggest "ceiling" for the development of LED projectors.











































However, the luminous efficiency of LED has improved rapidly in recent years. At present, the luminous efficiency of white light LED

has reached 20-30 lumens/W, and the highest has reached 60 lumens/W, which is getting smaller and smaller than the actual luminous efficiency required by the projector. In conclusion: At present, LED light sources have been well practiced in the application of rear-projection TV products. For example, Samsung, Sanyo, Zeiss, Epson, Akai, JVC and other companies have developed models for display. LCD, LCOS, and DLP display components are all used. The rear-projection screen can reach 55 inches. Although there is also a problem of insufficient brightness, the overall technical application is worth learning from LED projectors. LED light sources will bring more perfect color performance and greatly improve color reproducibility. At the same time, the small size and low power consumption will enable the projector to achieve real projection anytime and anywhere. The ultimate demands of projectors such as small size, long life, and fast shutdown can all be solved by LED light sources. Therefore, the LED light source revolution in the projection field is still worth our eager anticipation.