The overhead projector, also known as an overhead transparency projector or OHP, is a device that projects a magnified image of a transparent sheet onto a screen. It is most commonly used in classrooms and lecture halls, but can also be used in other settings.
The overhead projector was invented in 1932 by J.L. Love, a professor at the University of Denver. Love's original design used a light bulb to project the image, but later models used more powerful halogen lamps. Over the years, the overhead projector has been improved with various features, such as autofocus, remote control, and the ability to project images from a computer.
Overhead projectors are still used in many classrooms today, but they are being increasingly replaced by digital projectors. However, the overhead projector remains a valuable tool for teachers, as it is relatively inexpensive and easy to use. It is also versatile, and can be used to project a variety of materials, including slides, transparencies, and even 3D objects.