[Only buy the right ones, not the expensive ones, experts teach you to choose a good projection screen]

There are many kinds of projector screens, and the most commonly used by ordinary users are white plastic screens and glass bead screens. In order to pursue high brightness, many people tend to choose bead screens with higher gains. When the projector is placed on the desktop for front projection, there is no problem, but when the projector is suspended and front projection, the problem appears-the brightness and contrast are severely reduced, like a white gauze, and the effect is not even as good as the original projection. White wall. Therefore, when the projector is hoisted, do not choose a glass bead screen with light regression.
Projection Screen Selection Guide
Core parameters for purchasing projection screens
Gain or Screen Gain
　　The ability of the screen to direct incident light to the audience. The gain of a matte white wall is 1. If the screen gain is less than 1, the incident light will be weakened; if the screen gain is greater than 1, more incident light can be directed to the audience, but the viewing angle is small. For example, the image displayed on a screen with a screen gain of 10 is 10 times brighter than the image displayed on a matte white wall. Curved screens usually have greater screen gain than flat screens.
Viewing Angle
　　The screen does not reflect light equally in all directions. Most of the light is emitted in a cone shape around the 'best viewing line'. If you are within the conical viewing range defined by the horizontal and vertical viewing angles, you will perceive the maximum brightness. The half-gain angle refers to the angle that reduces the usual maximum gain value of the screen to 1/2 brightness in the visible range.
Characteristics of white plastic screen and glass bead screen
　　The white plastic curtain is directly made of coarse white-grained fabric without surface treatment. If you touch the surface with your hands, you can feel the rich texture. The characteristic is that it can show the performance of the projector as it is, without modification, low gain, large viewing angle, and natural color.
　　 glass bead screen, as the name suggests, the surface is coated with optical crystal glass balls, touch the surface with your hand, you can feel the tiny glass bead particles fall off. The characteristic is that the picture has a clear sense of focus and vitality, high gain, and small viewing angle. The biggest feature is 'light regressivity
Bead screen should not be used when the projector is hoisted
　　 If you choose the glass bead screen when the projector is ceiling mounted, the effect will surprise you. When choosing a screen, the desktop is usually front projection, and the effect is very good and bright. But when I returned to the classroom or meeting room, how to adjust the ceiling mounted projector, the brightness and contrast of the picture were very poor, as if it was covered with a white gauze. At this time, even if the ambient light is controlled to completely black, it will not help, so the final projection effect depends on whether all the links are reasonable.
　　 The interesting thing is that when the curtain is put away and directly cast on the white wall, the effect is better! And when you stand on the table and debug the projector, you will also find that the effect is great, but when you return to the ground, the effect becomes worse! This is the manifestation of the recurrence of light from the bead screen. When the light emitted by the projector is projected on the bead screen, it is reflected back to the direction of the projector, so people below cannot see the picture clearly.
　　 For the choice of economical projection screens, when the projector is hoisted or looking for a large viewing angle, such as classrooms or business presentations, white plastic screens are recommended. When high brightness is pursued and the projector is placed on the desktop for projection, it is recommended to choose a glass bead screen.