USB-T + RTL-SDR Realtek RTL2832U + R820T-T Tuner

Projection screen is one of the most commonly used products in the peripheral equipment of projector, projection screen is short for projection screen; If the projection screen is properly matched with the projector, you can get a good projection effect.
Projection screen can be generally divided into reflective type, transmission type two categories; Reflective type for forward projection, transmission type for back projection; Forward cast screen is divided into plane screen, arc screen; The plane screen can be divided into glass bead screen, metal screen, embossed plastic screen, elastic screen, etc. (embossed plastic is divided into white plastic, grey plastic, silver plastic, etc.). The current popular projection screen has glass bead screen, white plastic screen and metal screen 3 kinds.
The white plastic panel
The white plastic screen is white and smooth, and the light is soft. When the light around it can be adjusted, it shows the best projection effect. The light is balanced and scattered to each display area. The screen surface can be cleaned, moisture-proof, mildew proof, flame retardant, no peculiar smell, long use does not fade, does not yellow, does not deformation. Special photosensitive materials are used to better solve the scattering problem of ambient light. The visual Angle is 55°, but the gain is low, only about 1.5.
If white paper is chosen as the projection screen, there is no polarity diffusion, so the display gain (GS) is theoretically 1 in all directions. Screen gain refers to the brightness and efficiency of the specified viewing Angle.
A bead screen
Glass bead screen in the optical characteristics of the pursuit of improving the reflectivity, glass bead curtain in PVC cloth surface bonded with ultrafine glass beads, beads do not drop, glass beads uniform to enhance the reflection effect, increase the brightness gain (up to 2.8), the audience looks bright, three-dimensional sense strong. Reproduce vivid color, create beautiful visual effect. The curtain has the characteristics of moisture-proof, mildew proof, flame retardant, no yellowing, no fading, etc. Glass bead curtain viewing Angle is about 35°.
Metal screen
Compared with the traditional pearlescent screen, the metal screen creates a new projection concept, which filters the ambient light to the greatest extent, greatly improves the quality of the picture, and makes the projection effect of low lumen projection equipment get a leap. At present, it has been widely used in stations, airports, exhibition halls, exhibition halls, conference rooms and so on. Although the reflection principle of metal screen and glass bead screen is diffuse, but the reflection effect of both is completely different. A simple understanding of its reflection principle is necessary.
The reflection principle of the metal screen is very simple. In fact, the metal screen can not add color to the projector, it is just the quality of the projector to reflect the audience truthfully; And glass bead screen is the light, sunlight, projector light mixed together to reflect to the audience. Simply put, glass bead screen in natural light can not reflect the light of a single projector. The effective solution to the foggy white background of glass bead screen is to reduce the illumination of the environment. So the glass screen can only be viewed in a relatively dark environment.
The metal screen has the highest optical gain, but the screen is curved, so the viewing Angle is small; The optical gain of the flat pearlescent screen is low, but the viewing Angle is large. Milky white glass bead screen light gain in the center, the visual Angle is also larger. The rear projection screen has hard transmission screen and soft projection screen, hard transmission screen light gain is higher, the viewing effect is good. If the projection screen is properly matched with the projector, you can get a good projection effect.
Projection screen can be generally divided into reflective type, transmission type two categories; Reflective type for forward projection, transmission type for back projection; Forward cast screen is divided into plane screen, arc screen; The plane screen can be divided into glass bead screen, metal screen, embossed plastic screen, elastic screen, etc. (embossed plastic is divided into white plastic, grey plastic, silver plastic, etc.)