What are overhead projectors

A variety of projector types are there, but the overhead projector is most commonly spotted in business meeting rooms, conference rooms, and classrooms. Here we have penned down a general overview about it; you can have a look at it.

Overhead projectors display images either onto a screen or on the wall. It has a large box packed with a cooling fan, bright light, a long arm, and a mirror. Schools, colleges, and universities typically use this projector for presentation purposes. Its use has declined a bit in recent times, and more sophisticated and modern projector models are currently available.

What is an overhead projector?

Overhead projectors are popularly known as OHP. They work like film or slide projectors. In addition, light is primarily used for projecting and displaying images onto a wall or screen. You can display pictures, hand-written presentations, or other documents with ease. Moreover, the page-sized sheet comes as the image source. The sheet is made of transparent plastic film that is generally termed transparencies.

overhead projector

Main parts of overhead projectors

We all know that the existence of these projectors has become somewhat rare and less popular. But you can still utilize them to share older transparencies and end up experiencing a truly interactive and genuine presentation time. Its main parts are:

  • Lamp and Box
  • Fresnel Lens
  • Plate Glass
  • Upper Lens Assembly
  • Projection Media.

History of overhead projectors

The use of overhead projectors dates back to the time of World War II. Servicemen groups were being trained through it. Later on, in the time of 1960s, overhead projectors were spotted excessively in the classrooms and conference rooms. It is primarily meant as an educational tool and collected record sales in the 1990s.

The optical system of overhead projectors

An overhead projector is infused with any of three kinds of optics. The details about them are mentioned below:

  • Direct optics projectors keep the optics as well as the light source completely in a straight line. Moreover, these are inexpensive projectors and get comparatively quite hot when used for hours and hours.
  • Folded optics projectors come with a mirror generally placed between the lens and the lamp. This respective projector type delivers excellent resolution and keeps the image quality bright enough. It does not get hot even if you use it for prolonged hours. At times, it is also known as chamber optics projectors.
  • The reflected light optic projector has a premium-quality designed lens that enhances the picture quality. These days, it has become the most preferable pick.

Read more about that: Can Projector Replace Tv?

Source of illumination

The overhead projectors functions on the latest lamp technology. Modern illumination technology has been injected that you have commonly spotted in the DLP and LCD video projectors. Some overheads use high-power halogen lamps and consume 750 or 1000 watts. The lamp does not melt because the high flow blower prevents it from melting.

On the other hand, the older models of overhead projectors were installed with tubular quartz bulbs. They failed to provide enough screen illumination. These bulbs were replaced by integrated lamps that managed to send a maximum portion of light and keep the image brighter enough.

Source of illumination

The working mechanism of overhead projectors

Overhead projectors function by simply projecting, enlarging, and illuminating images with light. The image is projected smoothly onto the blank surface, wall, or screen. Its main components are a converging lens, a mirror, and also transparency sheets. Furthermore, the lens directs the light towards the screen. The image gets flipped by the mirror, and the transparency sheet displays the image onto the screen.

The target audience of overhead projectors

Students and office-going people extensively use these projectors. You have widely seen their prevalence in classrooms, conference rooms, offices, and business meeting rooms. These audiences are frequent and regular users of OHP. Lessons are taught in the classrooms by presenting them through the overheads. In addition, professional presentations are delivered via these projectors too!

According to experts, these projectors have successfully brought a budget-friendly interactive environment for office-going personnel and educators. When lessons and presentations are delivered in this manner, this automatically facilitates and encourages better communication between the presenter and the audience.

You can comfortably write on the plastic sheets, also known as transparencies, and enlarge the image as much as you can. You can replace the transparency sheet whenever it gets filled with the written material. Rest; you can restore the sheets and bring them to a new condition by washing them with soap.

The future of overhead projectors

The demand for OHP is somewhat getting low. More modern and computer-based projectors have taken their place. They used to be a popular and crucial tool for educational purposes, but more options are available now. During the time of 2000s, document cameras, interactive whiteboards, and dedicated computer projectors replaced them. 

Audiences show less preference for these projectors because they exhibit dim, not so bright, and fuzzy image quality. The projected image generally becomes excessively bright in the center and too blurry around the edges.

The linearity, sharpness, brightness, clarity, and optical focus of overhead projectors do not get matched with the present-time modern models. Thus, these are a few of the downsides that OHP possess, and we hope they sooner start working on these discrepancies.


Thus, that is all about the complete information on overhead projectors. We like to tell you that projectors are of enormous kinds. Lots of variations are there if you have planned to get a projector for personal or professional use. 

Like, you can have the 4K projector, LCD/LED/DLP projector, or laser projector. The choice is yours! You can forward us your experiences if you have used OHP ever during your academic or professional life. How great and effective did you find it? Stay tuned to receive more updates on other projector versions.

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