Point correction: the only way to differentiate the outdoor full-color LED display

The Olympic Wukesong basketball hall, stadium and the water cube in the large screen LED-display.cnLEDw.com/ >LED display is believed to have left a deep impression on the global audience, along with World Expo and the Universiade is approaching, LED display will also be widely applied to more venues and road traffic instructions. With the increasing demand for full-color display in sports venues and outdoor advertising, the proportion of full-color LED display in the overall market will continue to expand. Expected 2007-2010 years, China's LED display market CAGR will reach 15.1%, in 2010 the market demand will reach $7 billion 550 million.

Indoor and outdoor (including tunnel) large screen LED display is currently a niche market more profitable, in addition to large stadiums, but also widely used in highway toll stations, road signs, airport flight information display, wharf, port, train station, tunnel, game machine, city square, outdoor billboards, government office buildings and parking lot, some dynamic information for real time display.

LED display can generally be divided into two kinds of static and scanning screen, outdoor LED display mostly static screen, up to the use of the 2 sweep screen. Indoor LED display as a result of small spacing, the general use of more than 2 sweep scan screen (scanning screen refers to a drive output corresponding to the screen a few points, corresponding to the 4 point is the 4 sweep).

Currently used for road traffic indication of large screen LED display is a monochrome static screen, such as signs on the European highway generally use white LED display.

At present, European and Japanese suppliers (such as Lighthouse, MITSUBISHI and Swarco) with LED display quality is best done outdoor large screen traffic, Chinese seems only Shanghai think twice before doing outdoor traffic LED display, the market performance is not very prominent.

Full color LED display with accumulated MBI5036 LED driver chip

Asian LED display manufacturers are currently unable to enter the European and American highway market, because their products are still difficult to reach the European traffic standards EN12966. "Accumulation (Macroblock) company chairman Yang Lichang said," the design of outdoor LED large screen display technology is a comprehensive challenge, not only need to do not dead, but also need to have outstanding performance in optical design, system reliability, mechanical robustness, anti lightning and anti overheating. "

Lighthouse currently makes the largest LED display has reached 480 meters. Yang Lichang said: "the biggest challenge in the design of outdoor large screen LED display, in addition to compliance with the EN12966 specification, is how to maintain consistency, as far as possible to reduce maintenance costs. "

The EN12966 specification is a set of technical barriers in EU countries, access to all EU countries as well as Norway and Switzerland road traffic indicator LED display market must meet the requirements of EN12966, the specification requirements through the following six tests: visual performance testing, physical performance test, performance test, structure test, electromagnetic compatibility test of electrical requirements. Swarco VMS system product manager Lars MichEL said.

However, with the improvement of product differentiation and the emergence of high-end applications, full-color LED display screen is an inevitable trend of design and development, but it is also the most difficult design.

In addition to the optical and thermal design challenges, the main development difficulty of full-color large screen LED display is how to solve the problem of color, color and brightness uniformity. "Yang Lichang said," the reason is caused by color driver files, LED files and different different LED aging causes uneven color and uneven brightness in addition to the above three, there are driver current output error. So if you want to make a high quality full color large screen LED display driver chip, must choose the same grade of LED and high precision, but only do this, can not solve the problem of uneven aging of the most difficult LED, this problem must eventually use point to point correction method to solve. "

With the high-end LED display more intense competition, strict requirements of LED brightness uniformity and color accuracy, light on the quality of LED has been unable to meet the needs of screening; therefore, for each LED point to point correction to enhance the LED display quality, has become a trend. Point to point correction is the most new technology showcase International Symposium held in Chinese tour this year accumulation of LED technology, it requires the controller, image sensor (or light gun) and the complexity of the algorithm to achieve, the principle is to keep the same driving current but by adjusting each point on the conduction time to ensure consistency of brightness because, be consistent in the same drive current LED light color. Currently the latest accumulation of MBI5040 support 8 bit digital point correction function.

The MBI5040 is a constant current LED driver with 8 bit digital correction and a 16 bit PWM function. Most of the current market correction approach is through the controller operation, however, this way will increase the load and limit controller can control the LED points, not only the high cost, the controller design is complex. Built in MBI5040 digital point ZhengXin function, can be individually adjusted LED brightness uniformity, and avoid the general in the correction process, LED color offset problems. In addition, through the MBI5040 direct point correction operation, but also allows the controller to focus more on image processing.

General point correction can be divided into analog or digital two, however