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Projectors are widely used for showing corporate presentations, videos, and other kinds of visual content. They are available in many forms and come with a wide range of features. The older versions of projectors include overhead, desktop and slide projectors. However, with advancements in optical technology, projectors have also evolved and most people now use affordable and high quality digital projector units.
Here are some of the major categories of projectors from the past and the present.
Digital Projectors
Digital projectors have gained in popularity in recent years because they are ideal for both home entertainment and for business presentations. They are highly portable and their use is becoming so widespread that the word projector would soon become synonymous with a digital projector.
Digital projectors come in three variants ? CRT, LCD, and DLP. A CRT (cathode ray tube) projector is heavy and bulky but it is also quite durable. Its image sharpness is usually not at par with other variants, and it also lacks in terms of brightness. LCD or liquid crystal display projectors can display a sharp and bright image but they have a high replacement cost. DLP (digital light processing) projectors display the most superior contrast and color range. These latest, light weight and almost maintenance free projectors are perfect for use in home, office or school, but they come at a higher cost.
Overhead Projectors
Overhead projectors are popular for use in schools, offices, and auditoriums. There are two main variants transmissive and reflective. Transmissive overheads have a light bulb positioned in the base, while in the reflective overheads the light bulbs are positioned in the mirror apparatus. Transmissive projectors often need LCD screens, unlike reflective projectors, which can go with a wide variety of screen types.
Desktop Projectors
Desktop projectors, as the name suggests, can be fixed on a stand or a desktop. At the same time, they are quite portable and have features like changeable lenses, high definition images and user friendliness. They weigh just about three pounds and are useful if there is no fixed venue for presentations and you want to be able to carry them to wherever your event is taking place.
Opaque Projectors
Opaque projectors are ideal when you want to trace the projected images of book pages, drawings, paintings etc. and transfer them on a screen. They are used as enlargement tools, transferring images of physical content to a larger canvas for presenting it to the audience. They are known as opaque projectors because they display opaque materials by shining bright light on the object. Therefore, they usually require high luminosity bulbs and larger lenses. With projecting technology having changed so much, these projectors are hardly used these days.
Slide Projectors
Slide projectors are used to project images printed on transparent slides. These projectors consist of a rotating device which places individual slides between the lenses and the source of light, thereby projecting the image on the screen. Nowadays, these slide projectors come in a portable form with a retractable screen, but their use is also becoming rare.
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