The Overhead Projector

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by GrandinGlog
Last updated 6 years ago


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The Overhead Projector

History of theOverhead Projector

The overhead projector is used to display clear images on a screen or wall using plastic sheets. They are used to display data or images to large groups of people for better clarity.

What is the Overhead Projector used for?

The Overhead Projector

How does it work?

What advantages or disadvantages does it have over other technology?


The base in the overhead projectors is one of its most important parts. The base has a sheet of glass on top and an interior light inside it. The light is turned on by a switch on the side of the machine. When the light turns on, the only place of escape for the light is the glass on top of the base, so when pre-printed plastic sheets are placed on top of the glass, the light transmits through the glass, hits the mirror, and reflects off of it. Before the light hits the mirror, it passes through a lens that flips the picture upside-down. When light transmits through the lens, it reflects off the mirror above and is projected onto a screen. In order for the picture to be upright, the plastic sheet must be placed upside down on the projector.

The overhead projector was invented by Roger Appledorn, an engineerworking for 3M in the 1960's. Working in an environment that encouraged new ideas and inventions, Appledorn had come up with an idea to put use to thermo graphic imaging. He developed the first ever overhead projector with 3M.

Unlike a chalkboard, overhead projectors don't require continuous supplement of items, unlike chalkboards that require chalk to write with. The plastic sheets that are put on the projector are cheap and easy to replace. It can be reused many times before being thrown out. Another advantage would be that not all documents that are projected are made or printed beforehand. They can be hand written on the projector. Overhead projects are very clean to use and easy to keep tidy. They will not cause a mess like chalkboards do because of dust from chalks. Overhead projectors can be cleaned simply by wiping with a damp cloth. With an overhead projector, students will be able to see clearly because it can be adjusted to zoom in or zoom out. It is usually more clear and accurate than chalkboard drawings or writings because it’s much easier for teachers to write on papers than a board.

Using overhead projectorsto create art:

Man demonstrating one of the uses for an overhead projector:


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