| 摘要 |
The invention relates to an overhead projector consisting of a housing which accommodates the writing plate and the Fresnel lens, a support arm, mounted on the housing, for the projection head, which has a lens and a deflecting mirror, and a light source which illuminates the writing plate. The object of the invention is (apparently) to avoid with the aid of simple means the known trapezoidal distortion. The essence of the invention is that the deflecting mirror is cambered and/or that the area of the writing plate which is transilluminated is a trapeze, or can be restricted to a trapezoidal area.
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