Overhead Projector - Decline in Use

Decline in Use

Overhead projectors were once a common fixture in most classrooms and business conference rooms, but today are slowly being replaced by document cameras, dedicated computer projection systems and interactive whiteboards. Such systems allow users to make animated, interactive presentations with movement and video, typically using software like Microsoft PowerPoint.

The primary reason for this gradual replacement is the deeply ingrained use of computing technology in modern society and the inability of overheads to easily support the features that modern users demand. While an overhead can display static images fairly well, it performs poorly at displaying moving images. The LCD video display panels that were once used have fallen out of favor due to the limited resolution available and relatively dim, fuzzy image produced by the overhead.

The standards of users have also increased, so that a dim, fuzzy overhead projection that is too bright in the center and too dim around the edges is no longer acceptable. The optical focus, linearity, brightness and clarity of an overhead generally cannot match that of a video projector primarily due to the plastic fresnel lens, which can only approximate what would normally be an extremely large and heavy glass lens.

Video projectors utilize extremely small picture generation mechanisms, allowing for precision optics that far exceed the plastic fresnel lens' optical performance. They also include additional optics that eliminate the hotspot in the center of the screen directly above the light source, so that the brightness is uniform everywhere on the projection screen.

Critics feel that there are some downsides as these technologies are more prone to failure and have a much steeper learning curve for the user than a standard overhead projector. While a computer projection system eliminates the need to create hard copy transparencies (which can be quite expensive, particularly if made in color) of the slide show presentation, many presenters make both in case the computer hardware fails. Furthermore, the overhead projector allows a more direct interaction through live writing on the transparency.