What is the scientific principle of mobile phone anti-peep screen?

The name "anti-peeping film" may be familiar to everyone, but it is a common screen film in life, which is used on the screens of computers, mobile phones and other electronic devices. Some friends who pay more attention to privacy and don't want people around them to see the content displayed on their screens will stick a layer of anti-peeping film on the screen. After sticking the anti-peeping film, the visual range of the display screen with a large viewing angle is obviously reduced.

You can only see the screen content in a limited small angle in front of the screen, but only see the black screen outside the angle, which can effectively prevent others from peeping at the screen and protect privacy, so it is called anti-peeping film.

If you see someone smirking at the black screen phone next to you in the future, don't think he is sick. Visible field of view, then, why can the anti-peeping film with a flat appearance achieve such an anti-peeping effect? This comes from its microstructure. If only observed with naked eyes, the anti-peeping film looks similar to ordinary film.

But if you put it under a microscope, you can see something special. The anti-peeping film inserts a special micro-peeping structure layer-ultra-micro louver structure into the traditional laminated structure. Under the microscope, the anti-peeping film shows periodic stripes, because the surface of the film is engraved with many grooves.

They form a parallel and ordered grating structure, which limits the divergence angle of light emitted by the screen. By controlling the angle of light, the light can't penetrate the film at some specific angles, and the wide viewing angle of the screen is changed into a narrow viewing angle, so as to achieve the purpose of preventing voyeurism. The inspiration of this structure comes from the blinds that are common in life.

The louver controls the luminous flux by adjusting the direction of the blade layer and blocks the external view. Different from blinds, the anti-peeping film uses optical principle to achieve this goal, which will be explained below. The effect of different angle shading plates in the peep-proof structure layer can be seen from the above peep-proof film structure.

When the light emitted by the screen enters the anti-peeping film, the convex peaks on both sides limit the angle of light propagation, and only the light in a limited angle range in front of the screen can completely exit the film, thus limiting the viewing angle in front of the screen. Beyond this angle, the brightness of the screen drops rapidly, and it looks like a black screen.