Overhead Projector

A simple tool used to display images onto a screen or wall.

By: Katarina Akopians

When, and by whom was the Overhead Projector invented?

The overhead projector was created by a man, who worked at the company "3M", named Roger Appeldorn in the early 1960s. His product was a success when he reached out to local businesses and teachers in order to promote his final product. Shortly after, throughout the 70s, 80s, and 90s, the overhead projector played a huge role in teaching in classrooms across the country.

what is an overhead projector used for?

An overhead projector is used to enlarge images onto a blank screen or wall for an audience to view. The device is commonly used in classrooms for teaching. A teacher is able to write on a clear plastic sheet and place it on the overhead, the image would then projected onto the blank screen for students to view and take notes. The device is also used in business meetings for the same purpose.

How an overhead projector works

Overhead projectors have clear glass tops which would allow people to place clear plastic sheets with writing on them. When the light for the projector is turned on, the light would go through the plastic sheet.The light would go on everything except for the writing on the clear plastic sheet. When the light is turned on, the light would go through the glass top, hit the mirror and then the mirror would reflect the light through a magnifying window lens onto the blank screen. The image would then me shown on the screen for the audience to view. The image on the screen could also be adjusted to make it more clear by turning a nob on the side of the projector.

Advantages and Disadvantages the overhead has over other related technology

Advantages:


  • Teaching
  • Being able to use the chalkboard while teaching and having the overhead image
  • Does not need a dark room to be darkened making it easy to read
  • Requires no technology knowledge to operate


Disadvantages:


  • Constant power supply
  • Can only be projected onto flat white surface
  • If the surface is not suitable inclined at the correct angle
  • The image will suffer from a phenomenon called ‘key-stoning’
  • More likely to crack or break, must handle with care
  • Glare from projector hurts eyes
  • If you write too small on the paper it will not be easily read on the screen
  • They are overused in teaching because they are so convenient and easy to use
  • New technology like smart boards are slowly replacing overheads
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APA Refrences

Akanegbu, A. with Anuli Akanegbu Anuli is a writer. (n.d.). Vision of Learning: A History of Classroom Projectors. Retrieved from http://www.edtechmagazine.com/k12/article/2013/02/vision-learning-history-classroom-projectors


Overhead Projectors K.V. (n.d.). Retrieved 9 March 2015, from https://grade10optics.wikispaces.com/Overhead%20Projectors%20K.V.?responseToken=0184a29171f4f00f5a044866793d9ba58


Using Overhead Projectors in The Classrooms. (2013). Retrieved from https://csinan.wordpress.com/2013/04/11/47/


What is an Overhead Projector? (with pictures). (n.d.). Retrieved from http://www.wisegeek.org/what-is-an-overhead-projector.htm

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