The large-scale engineering electric projection screen adopts a roll-down structure. The roll-up shaft and the main drive shaft are separated, and the roll-up shaft is located under the screen (at this time, the straightness of the shaft no longer affects the flatness of the screen), and the upper end of the screen The movable positioning is adopted to effectively ensure the flatness of the screen; and the main drive shaft is no longer connected to the screen, and the middle part of the main drive shaft can be increased with support points, the straightness can be correspondingly guaranteed, and the service life of the motor can be correspondingly obtained. Protection. The conventional electric screen adopts the roll-up type, that is, the reel is located above the screen, and the reel shaft is shared with the main drive shaft. Due to the large span between the two fulcrums of the shaft and the large deflection, the screen surface is V-shaped and other undesirable phenomena. The screen is an electric lower scroll screen, which is rotated by the lower shaft to play the role of retracting and rewinding the screen material, while the ordinary screen realizes this function by scrolling up. The screen made in this way can reduce the weight of the screen a lot, especially suitable for large-size electric screens, and the flatness of the screen is flatter than that of the scrolled screen. The pendant is installed through the cover, which effectively guarantees the safety of the giant screen. The professional theater screen gain is 1.2, and the viewing angle is 160° (white and gray optional). The professional sound-transmitting screen is used to effectively prevent the large screen from vibrating due to air flow. The curtain is green and environmentally friendly, and the formaldehyde content is less than 20mg/kg, which fully meets the standard (a test report is provided). The curtain has the characteristics of light resistance, washing resistance, flame retardant, etc. It will not fade, yellow, change shape, and has no peculiar smell. It can be moisture-proof and mildew-proof (provide a qualified test report).