| 摘要 |
A circular projection screen having adjustable radian, comprising left and right upright columns (1) and a flexible projection screen (5). The upper end and the lower end of each upright column (1) are respectively provided with horizontal cantilever beams (6). An upper pull rod (3) and a lower pull rod (3) are respectively fixedly disposed between the left and right upright columns (1) having the same height as the upper and lower cantilever beams (6). Each cantilever beam (6) is provided with upper and lower parallel slide grooves, the cantilever beam (6) is provided with a rack (7) and a gear (11) engaged with the rack (7), and the two ends of the shaft of the gear (11) extend out of the cantilever beam (6). The shaft of the gear (11) on the upper side of the cantilever beam (6) is connected to a driving motor (10), and the shaft end of the gear shaft (11) on the lower side of the cantilever beam (6) is rotatably connected to a roller (12). An arc-shaped recess is formed on the periphery of the roller (12), and elastic round steel (4) is elastically mounted in an abutting manner between the recesses of the rollers (12) of the two upper end cantilever beams (6) and between the recesses of the rollers (12) of the two lower end cantilever beams (6). The central point of the elastic round steel (4) is fixed to the corresponding pull rod (3), and the upper and lower elastic round steel (4) is respectively connected to upper and lower edges of the flexible projection screen (5). The gear (11) moves along the rack (7) in an engaging manner, drives the roller (12) to move back and forth, and pushes the two ends of the elastic round steel (4) to move back and forth synchronously, so as to change the curve radian of the elastic round steel (4) and thus change the radian of the flexible projection screen (5). |
