It just narrow the angel of view and make the screen viewable only from the front side. The principle is quite simple. It's just like there are some small cannular structures that form the film. If the angel of view is not right, the things behind the film can't be seen.
Privacy protective film is anti-glare and anti-reflection that can control the incidence direction of light and protect commercial secrets and personal privacy. The content displayed on the screen can only be seen by the user from an angle of 45 degrees from the front side. Whoever standing on the two sides can see a black screen only. I have bought one from OK8.
What kind of privacy protective film are you talking about? Is it used on computer screen or car windows? However, no matter which kind it is, the principle should be the same. It's the use of polarization technology. The screen is viewable only from the front side and within the space that is 45 degrees to the front side. In this way, the content on the screen can only be seen clearly from the font side. But people who look at the screen from an angel of 30 degrees from two sides cannot see what's on the screen.
