| 摘要 |
The present invention relates to an over head projector consisting of a writing table which serves as a bearing surface or the original to be protected, a Fresnel lens arranged below said writing plate, a light source which illuminates the writing table and is provided with a capacitor, and a projecting head which is carried by a support arm and has a deflecting mirror and a lens. The object of the present invention is to configure an overhead projector such that in the overhead projector it is possible simultaneously to project a colour slide at a stronger magnification from one and the same writing table in addition to an image projected in the normal way. The invention achieves this object by means of a diaphragm which partly covers the writing table and has a window and an additional optical element which images the window in the diaphragm enlarged on the lens.
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