The future development trend of LED display point-by-point correction technology

1. Concept of point-by-point correction technology

The current status of LED chip production process determines that even if LED chips are produced in the same batch, there are still considerable differences in the luminous intensity and main wavelength between individual LED chips. For LED display applications, this difference will seriously affect the display quality. The indicators such as photometric, chromaticity and electrical parameters must be classified and screened by spectral separation before they can be applied to the same display screen .

However, the use of spectrophotometry and color separation to solve the problem of inconsistent light and color of individual chips cannot achieve perfect image quality due to insufficient precision, the influence of subsequent process flow, and inconsistent light decay during the aging process. In addition, the display screen that has been used for a period of time will also deteriorate in display quality due to inconsistent light decay and other factors, resulting in "flower screen", which is also beyond the reach of spectrophotometry and color separation.

Therefore, the industry tries to solve this problem from the last process of display manufacturing by using different drivers for different LED light points, which is point-by-point correction.

In the late 1990s, the theoretical prototype of point-by-point correction appeared at home and abroad, and the practical exploration of this technology began. However, due to the lack of applicable general data collection tools and technical barriers, the research on this technology has long been discontinuous and unsystematic, and it has been a state of lack of communication. Point-by-point correction also lacks a recognized definition. At present, the more complete definition is as follows:

Point-by-point correction means collecting the brightness (and chromaticity) data of each light point area on the LED screen , obtaining the correction coefficient for each light point (or the coefficient matrix for each pixel), and feeding it back to the control system of the display screen. The control system applies the correction coefficient to achieve differential driving of each light point, thereby greatly improving the pixel brightness (chromaticity) uniformity of the display screen.

2. Future Development Trends of Point-by-Point Correction Technology

After experiencing a long germination period of nearly ten years from the late 1990s to 2008 and a three-year rapid growth period from 2008 to 2010, point-by-point correction is about to gradually enter its mature stage in the process of accumulating theory and practice, further refining the division of labor, standardizing processes, unifying protocols, and normalizing evaluation.

2.1 Further refinement and specialization of technical division of labor

As the division of labor in the industry becomes increasingly refined and specialized, point-by-point calibration acquisition equipment is also showing a trend of separation from the control system and increasing specialization.

The pursuit of quality and the promotion of market competition have led more and more companies to adopt professional point-by-point calibration and acquisition equipment, solidifying point-by-point calibration as a standard process, rather than just an emergency measure after product quality problems occur. Only through professional segmentation can we achieve broad compatibility and enable professional teams in each segment to continue to focus on in-depth cultivation, complement resources, and promote technological progress.

2.2 Faster, simpler, automated and standardized

Point-by-point calibration technology has made epoch-making progress, from the initial machine calibration of a large screen, which took a month to complete the calibration of a large screen of nearly 200 square meters in one night. In the future, point-by-point calibration will continue to move forward along the path of efficiency, simplicity, automation, and standardization. This is an inevitable trend determined by industry demand. On the road to achieving this goal, in addition to the technological innovation of acquisition equipment, it also requires the cooperation and support of control system partners in the industry, the construction and promotion of industry standards, and the accumulation and exchange of experience of point-by-point calibration practitioners.

3.3 Data storage to module

LED display The manufacturing industry has always been based on order-based production. Now many large companies have begun to explore planned production models. On the one hand, it can shorten the supply cycle to generate competitive advantages. On the other hand, standardized production can generate benefits and competitive advantages in terms of scale and management. Planned production means module or standard cabinet inventory, which means a variety of combinations when shipping;

To meet the requirements of planned production, the best way to store point-by-point correction data is to put it on the module, rather than on the receiving card of the control system as most of them are now. When the module or cabinet is assembled into a display screen, the control system reads back the correction data on the module, or reads back the original data and generates the correction coefficient according to the correction target value and applies it. Such a technical structure will make data maintenance work easy after replacing the module. In fact, internationally renowned LED screen manufacturers, such as Barco and Lighthouse, all use this correction data storage method.

However, to achieve this goal, the industry still needs to form a unified data communication protocol between control systems and modules .