[How to choose the correct projection screen] Projection screen purchase common sense

Before purchasing a specific screen, you need to understand the main technical indicators of the screen

Gain 　　 The ability of the screen to reflect incident light. When the incident light angle is constant and the incident luminous flux is constant, the ratio of the brightness in a certain direction of the screen to the brightness in the ideal state is called the brightness coefficient in that direction, and the maximum value is called the gain of the screen. Usually the gain of a matt white wall is set to 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 will be reflected or refracted.

Viewing angle　　 The reflection of the screen in all directions is different. The farther away from the center of the screen in the horizontal direction, the lower the brightness; the viewing angle when the brightness drops to 50% is defined as the viewing angle. Viewing the image within the viewing angle, the brightness is satisfactory; viewing the image outside the viewing angle, the brightness is insufficient. Generally speaking, the larger the gain of the screen, the smaller the viewing angle (metal screen); the smaller the gain, the larger the viewing angle (white plastic screen, due to the care of students, education screens mostly use white plastic screens) glass bead screens are more popular.

Classification 　　 screens are divided into two types: reflective and transmissive in terms of function. The reflective type is used for front projection, and the transmissive type is used for rear projection. Front projection screens are divided into flat screens and curved screens. The gain of the flat screen is small, the viewing angle is large, and the ambient light must be weak; the gain of the arc-type screen is large, the viewing angle is small, and the ambient light can be strong, but the incident light reflected by the screen is different in all directions. In terms of texture, it is divided into glass curtain, metal curtain, embossed plastic curtain, etc., which are generally applicable.

Size　　The size of the screen is defined by the size of its diagonal. Generally, the aspect ratio of the video image is 4:3, and the educational screen is square. For example, a 1.83m (72-inch) screen, according to the Pythagorean theorem, will soon be able to conclude that the screen is 1.5m wide and 1.1m high.

After purchasing the projector, the following is to choose a suitable screen to match, to obtain the best projection effect.

Four main steps for selecting the screen correctly:

(1) Select screen type

Front projection screen: There are manual hanging screen and electric hanging screen type; two-leg bracket screen; triangle bracket screen, metal plane, curved screen.

Rear projection screen: A variety of hard rear projection screens (divided into hyperbolic screens and diffuse screens) and soft rear projection screens (diffuse screens); the screen effect of hard screens is better than that of soft screens.

(2) Choose the best screen size

Choosing the best screen size mainly depends on the area of u200bu200bthe space used and the number of audience seats and the arrangement of their positions. The first rule is to choose the screen that suits the audience-not the screen that fits the projector, which means that the audience's visual experience should be put first.

The following are some references for choosing the screen size

# The height of the screen should be such that the audience in each row can clearly see the content of the projection screen. # The distance between the screen and the first row of seats should be greater than 2 times the height of the screen. # The bottom edge of the screen is about 1.5 meters away from the ground.

(3) Choose the format (aspect ratio) that suits the needs of the projection equipment you are using

The list of common formats is as follows:

Image format

Screen ratio (width:height)

VGA signal

4: 3

Projector

1:1

NTSC standard

4: 3

PAL format

4: 3

HDTV (High Definition Television)

16: 9

Widescreen

1.85

(4) Selection of screen materials

The screen fabric you choose should suit the needs of your projector and audience. However, if one screen needs to be used by multiple projectors, the screen fabric should be selected to suit the needs of the projector with higher screen requirements. For example, when you have both a slide projector and a projector, because the light output of the projector is lower than that of the slide projector, you should choose the kind of reflectance (gain) parameter suitable for the fabric of the projector. However, since most projectors now have relatively high brightness, a Matte White screen with a lower reflectivity (gain) than a glass beaded screen can achieve better projection effects.

The information and parameters of several front projection screen fabrics are provided below for reference:

Screen material

Screen parameters

English name

Chinese name

Matte White

White Plastic Screen

Viewing angle: 50° Brightness gain: 1.1 The fabric is fireproof, mildew proof, and can be cleaned

Video Spectra1.5

VS 1.5

Viewing angle: 35° Brightness gain: 1.5 Fabric, fireproof, mildew proof, washable

Glass Beaded

Ball Bead Screen

Viewing angle: 30° Brightness gain: 2.5 Fabric, fireproof and mildew proof

Super Wonder-Lite

Metal Screen

Viewing angle: 40° Brightness gain: 2.5 Fabric is mildew proof and can be cleaned

Polarized Screen

Polarization Screen

Viewing angle: 35° Brightness gain: 2.75 Fabric, fireproof and mildew proof

High Power

High Energy Curtain

Viewing angle: 25° Brightness gain: 2.8 Fabric fireproof, mildew proof, cleanable

Dual Vision

Front/rear projection screen

Viewing angle: 50° Brightness gain: 1.0 Fabric fireproof, mildew proof, cleanable

Da-Mat

Rear Projection Soft Screen

Viewing angle: 50° Brightness gain: 1.1 Fabric fireproof, mildew proof, cleanable

Cinema Vision

Advanced home theater screen

Viewing angle: 45° Brightness gain: 1.3 Fabric fireproof, mildew proof, cleanable

Pearlescent

Advanced pearl curtain

Viewing angle: 35° Brightness gain: 2.0 Fabric fireproof, mildew proof, cleanable