Editing Overhead projector (section)

{{Short description|Device that projects a transparent image}}
{{More citations needed|date=February 2008}}

[[Image:OHP-sch.JPG|thumb|right|Overhead projector in operation during a classroom lesson]]

An '''overhead projector''' (often abbreviated to '''OHP'''), like a [[Movie projector|film]] or [[slide projector]], uses light to [[Projector|project]] an enlarged image on a [[Projection screen|screen]], allowing the view of a small document or picture to be shared with a large audience.

In the overhead projector, the source of the image is a page-sized sheet of [[Transparency and translucency|transparent]] plastic film (also known as "viewfoils", "foils" or "[[transparencies]]") with the image to be projected either printed or hand-written/drawn. These transparent sheets are placed on the glass [[platen]] of the projector, which has a light source below it and a projecting [[mirror]] and [[lens]] assembly above it (hence, "overhead"). They were widely used in education and business before the advent of [[video projector]]s.