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在北京科学会堂学术报告厅里,为了配合学术报告的需要,設有許多机电設备,其中的书写投影仪(光学黑板)、大型两射放映机、电动黑板和显微投影机,都是我国第一次制成的新产品。书写投影仪,又名光学黑板。是北京照相机厂根据国外样品設計改进的。这台仪器实际上并无黑板。它放置在讲台上报告人的右側。报告人面对听众一边讲,一边可用玻璃专用腊笔在薄膜胶片上书写描画。字迹图线經过透鏡放大之后,通过反射鏡反射到讲演人背后的銀幕上,就形成直徑2.2米左右,放大
In the academic hall of the Beijing Science Hall, in order to meet the needs of academic reports, there are many electromechanical devices. Among them, writing projectors (optical blackboards), large-scale two-projector projectors, electric blackboards, and microscopic projectors are the No. A new product made once. Writing a projector, also known as an optical blackboard. It is a Beijing camera factory that has been improved based on foreign sample designs. This instrument does not actually have a blackboard. It is placed on the right side of the reporter on the podium. While facing the listener’s side, the reporter can use a glass special wax pen to write a picture on the film film. After the lines of the script are magnified by the lens, they are reflected by the mirror onto the screen behind the speaker and form a diameter of about 2.2 meters.