Projection system is superior to flat panel display system
With the gradual promotion of multimedia teaching and the acceleration of the process of education information technology, the use of projection equipment to assist teaching in schools has become more and more common, in the end, which kind of projection equipment is better quality and more suitable for use in the classroom? The National Digital Audio, Video and Multimedia Product Quality Supervision and Inspection Center recently released the Liquid Crystal (LCD) projection and flat panel (FPD) display system in the field of education health and safety and system performance analysis research report (hereinafter referred to as the report) shows that: whether it is health and safety or system performance, the projection system is better than the flat panel display system.
According to reports, relying on the national digital audio and video and multimedia product quality supervision and inspection center evaluation platform, simulate the state of students' classrooms, the scene is oriented to the education field, the report takes liquid crystal (LCD) projection and flat panel (FPD) display system as the main analysis and research object. Through blue energy, flicker, working noise, brightness attenuation, contrast, viewing Angle, energy efficiency index and other indicators, the health and safety of the system performance are relatively comprehensive analysis. The objective test shows that the comprehensive evaluation of the projection system is superior to the flat panel display system in the practical environment of education field.
The Outline of the National Medium and Long-term Education Reform and Development Plan (2010-2020) states that it is necessary to "accelerate the construction of education information infrastructure" and "by 2020, basically complete the education information system covering all types of schools at all levels in urban and rural areas, and promote the modernization of educational content, teaching methods and methods." As an important part of education information, electronic whiteboard and other interactive display systems are increasingly applied to teaching, which not only solve real-time and convenient problems, but also bring health and safety problems, especially eye health can not be ignored. According to the survey data of the Ministry of Education, there are more than 400 million myopia patients in China, and teenagers have become "the hardest hit area", the myopia rate of primary school students is more than 40%, and that of middle school students is 70%.
Hu Peng, the first author of the report and an engineer at the National Quality Inspection Center for Digital Audio, Video and Multimedia Products, said that in the field of education and teaching, the impact of various display systems on the health and safety of students needs to be demonstrated. This objective test is based on the evaluation platform of the National Digital Audio, video and Multimedia Product Quality Supervision and Inspection Center, simulating the state of students in the classroom, focusing on the auditory experience.
It is understood that the blue light energy is to detect the strength of the blue light radiation energy of different display devices, and the higher the blue light energy value, the greater the possibility of long-term viewing damage to the human eye; Flicker is to detect the flicker degree of different display devices, the more serious the flicker, the stronger the human eye fatigue will become, the more fatigued; The smaller the noise value, the lower the discomfort; Contrast is to test the white and black ratio of different display devices under various test legend conditions, including on-off ratio (all white/all black contrast) and checkerboard contrast, to measure the contrast characteristics from multiple angles; The viewing Angle is to detect the brightness viewing Angle of different display devices at different distances. Its size determines whether students in different positions of the classroom can see the same teaching content. The larger the viewing Angle is, the better it is for students. The energy efficiency index is the ratio of power consumption, brightness and display size of the display device when displaying different contents.
The test results in the report show that the blue light energy of FPD is generally higher than that of projectors, which is about 3 times, 1.5 times and 3 times of the blue light energy of projectors respectively. The probability of human eye damage caused by FPD is about twice that of the average caused by projection system. In terms of flicker index, the flicker energy of the two FPD systems is much higher than that of the projection system, and the fatigue caused by flicker is more likely to occur in the FPD system compared with the projection system. In terms of working noise indicators, the difference of working noise between the two display systems is less than 1dB, which is difficult for human ears to distinguish, and both are within the acceptable ideal range.
In addition, in terms of brightness attenuation index, the brightness attenuation of projection system is the smallest, and the average attenuation is smaller than that of FPD system. In terms of contrast index, in terms of black and white contrast, the projection system is much higher than the FPD system, and in terms of checkerboard contrast, the FPD system is slightly better than the projection system, but in actual application, the picture contrast is above 50:1, so the two levels are equivalent, and each has its own advance and fall. In terms of viewing Angle, the brightness of the projection system is basically the same at different distances and different angles, and there is no dead Angle during viewing. The viewing Angle of the FPD display system is between 40° and 60°. In terms of energy efficiency index, the projection system has advantages over the general flat panel display system.
(from the original Chinese quality The original link: http://epaper.cqn.com.cn/html/2015-09/11/content_44064.htm?div=-1)