From projection to interactive smart tablets, students’ vision threats are decreasing

[Hui Cong Education Equipment Network] While the national education informationization continues to advance, the teaching equipment has also undergone a change from chalk + blackboard to projection + whiteboard to integrated interactive smart tablet. While enjoying the convenience and efficiency of information-based teaching, people are also beginning to worry: Will these high-tech information-based teaching devices have an impact on students' vision health?

There is no doubt that the technical support of the equipment itself is the first priority.

If this is a poisonous apple, it doesn't matter if the child just wants to touch it or take a bite. As long as it is dangerous to approach, the first priority is naturally to stay away. Therefore, to determine whether the interactive smart tablet and projection are harmful to the student's vision, first of all need to confirm whether its key technical parameters are within the health value range, that is, whether it is a "poisonous apple". We know that several dimensions of display devices affecting vision include: blue wavelength, flicker frequency, sharpness, contrast.

Why are people still worried about "blue light hazard" to this day?

The source of fear is probably the lethality of "blue light hazard". First look at the "blue light hazard" is what? For light, the higher the frequency, the higher the energy and the stronger the penetration. While blue light is a high frequency band in visible light, if the display device is in color display, the blue light energy is more than enough to make our eye retina insufficient to convert all blue light energy into nerve electrical signals. Then, the excess blue light will pass through the retina and directly illuminate the fundus tissue at a deeper level, thereby accelerating the aging and lesions of these eye tissues, causing eye damage and even causing macular lesions. It is so lethal, so fear.

As for this key factor, as early as 2015, the National Radio and Television Quality Inspection Center published an experimental report on the “Blu-ray” pollution of teaching multimedia display devices. The report shows that the measured "blue light hazard" values ​​of two common informational teaching devices are: interactive smart tablet 0.54W•m-2•sr-1, laser projector 10W•m-2•sr-1, Its international standard of safety is: 100W•m-2•sr-1. It can be seen that the measured value of the interactive smart tablet is far outside the warning line. If you know this data, it will definitely reduce people's concerns. The "contamination value" of the laser projection is higher than that of the interactive smart tablet, but it is still Being within the internationally accepted standards, within the scientific and reasonable use methods, it will not cause visual damage to students. In addition, many schools are now gradually replacing the interactive smart tablet with the smallest "hazard value". The visual threat of students is gradually decreasing, and all kinds of concerns are unnecessary. People only stare at possible threats, but ignore the improvements brought about by technological progress. Unclear status can also be fearful.

Interactive smart tablet comes on stage, the screen flickers and drifts away

With the continuous advancement of liquid crystal display technology, as long as it is a slightly well-known brand, there will be no screen flicker. However, the reason why this is discussed is because the teaching projection is prone to screen flicker in the case of long-term maintenance. In such a situation, it is easy to cause fatigue and dizziness to the student's eyes. The fuse that people worry about. In fact, when the classroom is replaced with an interactive smart tablet, the flashing situation basically no longer exists (only for the first and second line brands, the small workshop unqualified products are not discussed).

It can also be seen from the following two Flicker test waveforms: the measured value of the projection is higher than -45dB - the blinking frequency that the human eye can feel, but the interactive smart tablet with the same age is still within the safe value.

Projecting Flicker test waveforms

LCD flat panel Flicker test waveform

From projection to interactive smart tablet, display clarity and contrast are rising

The clarity and contrast of the display is the two most intuitively visible aspects of the human eye, in addition to flickering, and one of the most intuitive changes from projection to interactive smart tablets. We know that projection has a big advantage because its price is low, but the advantage is that its display clarity is low, and the contrast is reduced in a classroom environment with daylight. It is often necessary to pull up the curtains when using the projection, which is why "the most suitable scene for projection is the cinema". When the curtains are pulled up, the overall environment of the classroom becomes dim, and the lack of light brightness not only damages the students' vision, but also is not conducive to creating a bright learning environment and affecting the quality of learning.

The interactive smart tablet is based on liquid crystal display technology, which solves this problem well – even in bright light, the screen can clearly display the picture and return the bright and comfortable learning environment to the students.

Of course, "If a criminal wants to commit a crime, fruit can also be a weapon."

Driven by science and technology, interactive smart tablets have alleviated many people's concerns. The interactive smart tablet of the formal brand is not a "poisonous apple". But if a criminal wants to commit a crime, the fruit can also be a weapon. Therefore, instead, the use of informational teaching equipment should be worthy of consideration. We all know that TV sets are harmful to people. It will cause harm to people's vision after long time, lying down, close-up, etc. What is the interactive smart tablet in the classroom? What are the scenarios that can make it a threat to your child's vision?

Long-term use bears the brunt. In the final analysis, visual acuity is caused by visual fatigue. Long-term viewing is likely to cause eye fatigue. Whether you have enough eye rest is very important for eye health. This is also why some big brands of interactive smart tablets will design a one-button black screen function, which can promote the teacher to use the device for a period of time (such as 20 minutes), you can put a black screen on it, so that students can rest their eyes.

The technology products themselves are safe, and the real harm is the inappropriate use. The interactive smart tablet adds protection locks to students' vision under the advancement of technology.

Editor in charge: Jia Wei