Multimedia classroom: showing where the crux of security is

[Hui Cong Education Equipment Network] The new semester is about to begin. At this time of the year, the "eye safety" problem displayed by multimedia teaching will be re-proposed to "chew the tongue". In society, many parents are worried about this issue.

Indeed, as a parent, "watching TV" is a big problem for children's eye problems. When Daping Jun was young, she was also told by her mother not to "continue to watch" TV. Even watching TV for a long time has become a major contradiction between children and adults.

Now, with the popularity of teaching multimedia devices, most regions have already implemented multimedia display devices in “every classroom”. The annual sales of teaching multimedia products exceeds one million units. If the teacher uses these devices at a high frequency, the so-called "safe old stalk: only two hours of TV per day", I am afraid it will be ruthlessly broken. What's more, the current students can watch TV, multimedia, as well as mobile phones and computers.

Multimedia classroom: showing where the crux of security is

In this realistic context, Dapingjun understands parents who are worried about their children's eyesight safety. Especially for primary school students, vision is still in the developmental stage, and the more fragile physiological state determines their sensitivity to eye health. In fact, research data shows that most cases occurred in primary school at the beginning of myopia. There are three reasons for this: First, the eyeball development is not yet fully mature; the second primary school student is very strong, but the self-control is insufficient; third; the primary school students already have a heavier academic burden.

Therefore, the focus on eye health in multimedia classrooms is also more in the field of primary school. However, Daping Jun feels that paying attention to eye health does not mean opposing multimedia teaching. In particular, it does not mean opposing multimedia teaching equipment.

For example, take the blue light pollution that is more powerful in the past two years as an example. In 2015, the National Radio and Television Quality Inspection Center published an experimental report on the “blue light” pollution of teaching multimedia display devices. The report shows that the measured teaching multimedia "blue light hazard" values ​​are: interactive smart tablet 0.54Wm-2sr-1, laser projector 10Wm-2sr-1. These two values ​​are much lower than the internationally accepted safety standard: 100Wm-2sr-1.

That is, our current teaching display equipment itself is technically sound, safe and reliable. This is also the reason why the state dares to fully implement multimedia teaching. In addition, multimedia teaching has another advantage: a more vivid way to improve classroom efficiency, focus on students' attention, and deepen the memory impression. In the case of a certain amount of knowledge required to be taught, these changes are equivalent to “the multimedia classroom actually liberates the child’s free time. The more traditional writing and repetition are the main ways of memory, which is beneficial to the child’s diversified approach. And use eye health."

However, this is not to say that the widespread use of teaching multimedia products is “no harm”. Dapingjun observed that how to use these devices is a more "serious" eye health problem than the devices themselves.

The formation of most eye health injuries, myopia, etc. has a distinct medical characteristic - that is, these changes are "accumulative". What is the accumulation? That is to say, the safety level per unit time has become a long-term “total excess” due to lack of attention to intermittent cultivation, exceeding the safety level.

Just like when I was a child, my mother’s reminder: TV can’t always look at it, watch it for a while, rest in the middle, and have a total amount of control every day. Nowadays, children need to follow this principle when watching TV, playing mobile phones, and playing computers. Classroom multimedia teaching is no exception. A viable method, such as if you don't use video content in your teaching, you should turn off the monitor in time. Under one lesson, the use of video content is best controlled at 60% of the total classroom length. In particular, do not use multimedia display devices for a long time in a dark environment.

For the latter, Dapingjun needs to be specially explained: in recent years, interactive flat panels and laser projections have gradually replaced traditional projectors. The important reason is that the former basically does not need the "black curtain" mode of "drawing curtains". Saying goodbye to the limitations of the dark environment not only helps the wide application of teaching multimedia devices, but also helps students to use eye health.

From the working principle of the display device, how can the display device display a clear picture? The core is the brightness and contrast indicators. In general, the brightness level of the display is higher than the surrounding environment, so that the picture looks clearer and more beautiful. At the same time, the contrast level should be as high as possible. The fixed contrast ratio is hundreds to one, and the minimum is above 100:1. The latter guarantees the level of darkness and resolvability between the details inside the picture. For a good display device, it should be as high as possible contrast, moderate, or even low brightness - at the same time, a good contrast effect, can make the display is not too bright, but also looks at the level of detail Full.

However, when the monitor is working, it is always subject to ambient light interference. The reflection of the ambient light directly impairs the actual contrast of the displayed image. Whether it is liquid crystal, OLED or laser projection electronic whiteboard, it is an important technological breakthrough direction against ambient light. A display system that effectively counters ambient light eliminates the need for higher total brightness for clear images. A display device having a higher total brightness and a greater difference in brightness from the display environment is more likely to cause eye fatigue and accumulated lesions and damage.

In this regard, regarding the display device, or the device for teaching multimedia, Dapingjun especially wants to say: a suitable brightness is very important. What is a suitable brightness? It is necessary to take care of the display effect, but also to integrate the perspective and distance of the viewer, especially to control the brightness level of the application environment - for example, in the classroom in the morning sun, when the sun is good, teaching multimedia It is still necessary to pull the curtains for use; in classrooms with poor lighting conditions, it is necessary to cooperate with the necessary lighting equipment.

In short, Daping Jun believes that "eye health of multimedia classrooms" ultimately has the following aspects: 1. reliable equipment; 2. good usage habits; 3. controllable total usage level; 4. must be sufficient Eye rest; 5. Appropriate use of ambient brightness levels.

However, to achieve the above five aspects does not mean that “parents” can “completely reassure”. Because the above problems are all "school links", which is the teacher's controllable link. Nowadays, the chances of children touching various display devices such as TVs, mobile phones, and computers are too high. Many times, winter and summer vacations have become the "most dangerous areas" for eye health. That is, the weight of the social eye and the family eye is more than the teaching eye.

Dapingjun has seen such a case: parents are giving their computers or mobile phones to their children in order to do their own thing; after 10 o'clock in the evening, the children are still staring at the computer to play games - and basically do not open lighting fixtures; Or, in order to secretly play mobile phones and play games, children hide in the bed after turning off the lights; and after using computers and mobile phones for a long time, under the fatigue, improper application posture, too close viewing distance; the so-called not playing computer, Turning around and picking up the phone... The eye damage of these acts is far more than the classroom multimedia teaching equipment.

Of course, entering the classroom with multimedia teaching is a historical trend. In the modern information society, children's exposure to more information equipment and technology will inevitably increase the child's eye load. This is something that cannot be avoided. In this regard, Dapingjun believes that “parents and teachers are responsible”: In the past, perhaps our main job was to “tune posture and control total”, which is a restrictive management. Now more need to "manage the content, tube structure", is the management of grooming.

What is the management of grooming? That is, the use of display devices cannot be avoided in the information age, so it is necessary to use limited eye time in the total amount of health, frequency of health, and healthy habits. "The place. This undoubtedly means that the responsibilities of parents and teachers are even more important. In this regard, Dapingjun can sum up “use eye health and have a long way to go”.

Editor in charge: Liu Yaoqi