Prospect Analysis of COB Display Screen in Cinema Application
Abstract: With consumers demanding higher standards for visual experiences, more advanced display technologies have been applied to end user field of film market. Among these advanced technologies, the most cutting-edge is LED screen. Compared to the traditional cinema projection system with a screen, LED screen has advantages in display effects, and they are expected to lead a visual revolution in the cinema display field. However, for LED screen to make a mark in the cinema application sector, products themselves must obtain DCI certification firstly. Without DCI certification, any large display screen cannot obtain the ticket to enter cinema industry.
Key words: LED screen, cinema market, DCI certification
Introduction: With development of LED display industry, the environment characterized by continuously decreasing pixel pitch, ongoing exploration and innovation in LED display applications, constant pursuit of higher resolution and clearer display effects, COB (Chip-on-Board) display screens are gradually applied in cinema display field.
I. Background Analysis of Cinema Market
The film industry’s value chain is primarily composed of four main parts: production, distribution, cinema chains, and theaters. Theaters represent downstream end of the entire industry chain, distribution in the middle, cinema chains serve as a link between the middle and downstream.
In recent years, film and television industry has been significantly impacted by COVID-19 pandemic. The ongoing fluctuations during pandemic have not only affected box office revenues but also the entire film industry value chain, thereby influencing the recovery process of film industry. With the improvement in the pandemic situation, the domestic cinema market began to gradually recover in 2023, and cinema attendance rates experienced a sharp increase.
Since May 2021, LED movie screen sector in China has witnessed a significant development, with companies such as Unilumin, Timewaying, AET, MG Screen, and CVTE successively announcing their attainment of DCI certification. This series of certifications signify that China LED movie screen manufacturers have reached internationally recognized high standards in terms of technology and quality. This not only promotes the thriving development of China LED movie screen industry but also provides cinemas with more high-quality domestically produced options, consolidating and enhancing the position of LED movie screens in the market. In the future, the domestically produced products of these companies will inject more innovation and vitality into LED movie screen market. The acquisition of these certifications is not only a testament to the strength of the companies themselves but also a crucial step for China LED movie screen industry to enter the international market.
II. DCI Certification Requirements
1. Display Effect
DCI certification sets extremely high standards for the performance of display screen, particularly requiring LED displays to achieve as close to 100% coverage as possible in the DCI-P3 color space. This certification includes two different testing modes, specifically designed for SDR (Standard Dynamic Range) and HDR (High Dynamic Range). The core aspects focused on during the testing process include breadth of color gamut, color accuracy, and grayscale linearity, etc. Through these rigorous testing standards, the certification ensures that LED displays achieve the industry’s highest levels in color reproduction, grayscale performance, and other aspects, meeting the stringent requirements of professional cinema and broadcasting industries for high-quality images.
2. Safety Requirements
For cinemas, the security of film sources is of paramount importance because the theft of film sources can result in incalculable losses. Key Delivery Message (KDM) generated during Digital Cinema Package (DCP) creation process is designed to prevent piracy, but this is only a part of the security measures. Since video signal output from Integrated Media Block (IMB) has already been decoded, pirates may find ways to obtain the decoded film source through other means. To mitigate risks to the maximum extent, server manufacturers typically require the implementation of more stringent security measures. These mechanisms aim to ensure the security of cinema systems and protect cinema businesses from the infringement of piracy activities.
III. Analysis of the Advantages of COB Display Screens in Cinema Display Application
COB screen exhibit significant advantages over traditional projectors, primarily in point-to-point display, high brightness, and intelligent brightness adjustment. By comparing the technical characteristics of COB screen and projectors, the use of COB screen in cinemas not only meets the audience’s demand for high-quality images but also aligns with national standards for cinema management. In terms of display quality, reliability, and safety, COB screen has revolutionary advantages over traditional projectors.
1. High Contrast and Brightness
Currently, COB display screen brightness can easily reach 1000 cd/m². With rapid development of COB packaging technology, improvements in high refresh rate technology and low-brightness & high-gray technology for displays ensure that the brightness of LED display screens can maintain complete grayscale display even when below 500 cd/m². This ensures that the display screen is not affected by any external environmental factors.
The luminous devices commonly used in COB screen for cinema often adopt 2020 or even smaller black LED light-emitting chips. Additionally, the sealing process for display panels involves black color. Therefore, compared to projection screen, there is a significant improvement in LED screen.
2. Wider Color Gamut
As surface-emitting, dot-matrix controlled display device, COB screen has an ultra-wide color gamut. This is attributed to the development of LED light-emitting diode technology, where LED light-emitting chips are selected through filtering to choose emitting chips with an extremely wide wavelength range. It is done to cover a broader color gamut space.
With CIE-1931 color space standard, the widest color gamut in the current display field is DCI-P3. The color gamut range of LED screen can easily cover the NTSC color gamut, REC.709 color gamut, and REC.2020 color gamut. Furthermore, through filtering LED light-emitting chips, it can also achieve coverage of the entire DCI-P3 color gamut.
3. Frameless Design
Seamless splicing feature of COB screen means no obvious borders between screens, providing audiences a more immersive viewing experience. In contrast, traditional projection systems may have visible transitions at the junctions of multiple screens, thereby affecting the overall visual experience.
4. Fast Response Time
COB display screens typically have fast response time. Currently, cinema screen solutions based on NovaStar solution can support frame rates as high as 240Hz, even 360Hz. It significantly reduces image ghost and blurriness issue, particularly enhancing performance in high-speed action scenes. This is crucial for cinema, especially when playing scenes with high demands such as action movies.
5. Flexible Installation and Layout
COB display screens can be flexibly customized and installed according to the specific requirements of a cinema, adapting to different screen shapes and sizes. In contrast, traditional projection systems may be constrained by factors such as venue and projection angles.
6. Energy Conservation and Environmental Protection
COB display screens based on flip chip technology, typically have lower energy consumption. In comparison, traditional projection systems may require more energy to achieve similar brightness levels. This aligns with the current global focus on energy efficiency and reducing carbon emissions.
We firmly believe that with continuous reduction in prices along the COB screen industry chain and more display screen manufacturers obtaining DCI-P3 certification, COB screen will rapidly replace traditional projection technology and become the leading force in cinema screen end user market. This trend will bring audiences a superior viewing experience in the cinema and drive the entire industry forward.
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