Shulou(Shulou.com)11/24 Report--

Not long ago, there was a "anti-peep film" related to the news on the hot search. The main idea is: when a traffic star was photographed in public, the conversation on the mobile phone was clearly seen.

What's even funnier is that some people in the comments suggested buying an anti-peep screen, but others said that it was already an anti-peep screen (that is, an anti-peep film).

Wait, what on earth is an anti-peep film? Does it really prevent others from seeing our mobile phone screens?

Anti-peep film: stick a miniature "shutter" on the screen. In fact, in today's smartphone era, all your personal information, whether it's work and family details, or privacy such as chat records and love life, or even ID cards and bank cards, may be displayed on a small screen. Once the mobile phone screen is targeted by people with ulterior motives nearby, I am afraid it will cause big trouble.

So, in order to make the phone screen more secure, a simple way is to spend dozens of yuan and paste an anti-peep film on it, so that strangers on both sides of the phone will not easily see the content displayed.

Why does the Pixabay mobile phone anti-peep film have such an effect? The secret lies in its structure.

The film looks transparent on the outside, but it is actually equivalent to a miniature "shutter", with a row of "small fences" blocking light in a fine raster structure of tens of micrometers thinner than a hair.

Figure? posts.careerengine.us can see from the above picture that if the human eye looks directly in front of the phone at a very small angle (such as 30 degrees), the light emitted on the phone screen can be received normally, while for the viewer on the side of the phone screen, the phone screen seems to be "black" because of the "small fence" array. Relying on this simple and direct way, anti-peep screen can protect the personal privacy of mobile phone users to a great extent.

Of course, the size of the "viewing angle" is not a fixed value, but is related to the width, height and spacing of these "small fences" and can be designed artificially.

It is not easy to design the size of the "viewing angle". Because mobile phone users often look sideways when watching the screen, such as raising or lowering the phone when taking photos, the viewing angle of the user and the bystander is actually about the same. Therefore, if you set this angle smaller, others will have less chance to steal the contents of the screen, but may also often prevent their normal viewing; if you set this angle larger, you don't have to always "sit upright" looking at your phone, but it's also easier for others to peek.

What should I do? Mobile phone anti-peep film designers can only strike a balance between the two, making the "viewing angle" at a compromise, but sometimes it still fails to meet the demand, resulting in "things that should not be seen" or "things that should not be seen".

A sign from an anti-peeping angle: @ Wang Fangwei / Zhihu besides, everything has two sides. This "shutter" structure on the anti-peep film will not only block peeping, but also inevitably block part of the light when you look at the screen, resulting in a decline in screen brightness or increased power consumption and other negative results.

A reverse brain: turn your phone into a "naked eye 3D" effect with an anti-peep film, naturally to prevent your screen from being peeped. However, there are times when we do the opposite, not only without stopping the "enthusiastic audience" looking sideways at the screen, but also by giving them the image content so that they "have to see it even if they don't want to see it."

So how do you do that? As long as another kind of film is affixed to the phone or computer screen, there are still many small fences inside the film, but it is slightly different in design, such as the one shown below.

The result of picture Wikipedia is that when you look at the screen from two different angles, you will see different parts of the screen in red and green respectively.

If you set the angle smaller, the red and green areas correspond to the left and right eyes of the person. One of the important reasons why we usually look at things and have a three-dimensional feeling is that due to the slightly different positions of the left and right eyes, there will be differences in the pictures of the same objects.

When the left eye picture and the right eye picture are mixed and displayed on the screen as red and green areas respectively, and then the two sets of pictures are projected to the left and right eyes respectively through this film, and the left and right eye images are combined in the viewer's brain. The effect of naked eye three-dimensional display can be achieved. With such a layer of film attached to the mobile phone screen, coupled with special binocular format image and video files, you can use a 2D mobile phone as a 3D mobile phone.

If the angle is set larger, through this film, two viewers from different angles can see different parts of the screen, which can be "dual-use of one screen" and "do their own things". For example, on a screen, one is watching a movie and the other is typing and chatting.

Keep thinking: what if you wear an anti-peep film on your eyes? Let's be inspired to think about a possibility--

Sticking a film on the mobile phone screen, whether it is anti-peeping or three-dimensional display, is actually equivalent to putting "a pair of glasses" on the mobile phone screen, and the glasses could have been worn on the human eye, so, what happens if you wear this "anti-peep film glasses" on the human eye?

Here I would like to interrupt to talk about the polarization of light. Light is a kind of electromagnetic wave, and when it propagates in the same brightness and in the same direction, it will vibrate in different directions, that is, the direction of polarization is different, and the light in different directions of polarization is the same on the outside. After the special detection of polarized light polarizer will "show the original shape". Polarizer glasses can be used not only for 3D display, but also for anti-peeping.

The kind of 3D movies with glasses that we usually watch in the cinema, such as "Avatar", "the Avengers" and "Spider-Man", are used in such a way. the screen shows light in two different directions of polarization. for example, left-handed circularly polarized light and right-handed circularly polarized light, the left and right eye pictures are displayed with two kinds of light, and the left and right eye polarized lenses on the glasses filter the polarized light in the corresponding direction respectively. In this way, the 3D display of binocular parallax is realized.

When preventing peeking, a composite image is displayed on the phone screen, which contains both the hidden image shown by polarized light in one direction and the noise interference shown by polarized light in another direction. If you do not wear special glasses, the mixed result is a piece of "white flowers", and the user wears polarizing glasses corresponding to the first direction of polarizing light, and the hidden image can be "filtered" out and still watch the mobile phone screen normally, while people without glasses can only "worry and stare, there is no way". Of course, the disadvantage of this anti-peeping method is that it is not very convenient to wear special glasses every time you use a mobile phone.

A hidden image display device using polarized light. The author was photographed at Huaqiangbei Museum in Shenzhen. In fact, a similar principle can explain the stunt of perspective mahjong tiles and playing cards in many "God of gamblers" films-polarizers can extract originally hidden patterns and cheat in gambling by allowing only polarized light in a special direction to pass through.

The screenshot of the movie "God of gamblers" is over and back to reality.

"preventing screen from being peeped" is indeed a more and more important issue in our daily life. Fortunately, with the rapid development of technology, it is believed that there will be many other ingenious technical means to solve the problem of privacy protection of mobile phone screen or other screen content, but the most important thing is that users should pay attention to their surroundings when using their mobile phones in public places.

This article comes from the official account of Wechat: fruit Shell (ID:Guokr42), author: Jiao Shuming, Editor: Maiya Yang

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