| 摘要 |
A motorized bottom masking assembly for variably masking a lower portion of a large curved picture projection screen, including a bottom mask movable to various heights along the lower portion of the screen having a rigid bar member defining the uppermost edge thereof, and at least three bar positioning lift assemblies located entirely below the bar member coupled to the bar member near opposite ends thereof and near the middle of the bar member. Each of the three lift assemblies include an elongated base track, a pair of lift arms arranged in upwardly converging inclined relation having lower end roller carrier assemblies guided by the associated base track movable toward and away from each other and having upper ends coupled together to the member, a lead screw coupled to the roller carrier assemblies, and a drive motor therefor for converging and diverging the associated pair of lift arms relative to each other to raise and lower the bar member relative to the base track.
|
