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How do Overhead Projectors Work?

Started by VelMurugan, Dec 07, 2008, 02:59 AM

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VelMurugan

How do Overhead Projectors Work?

Overhead projects work with the help of transparencies. All data are printed on top of the transparencies.

Before starting up, be sure to have a socket with live electricity where you can switch the overhead projector. The power buttons are usually made of first class plastic, the "click" sound is heard; it means it has been successfully put "on". If the overhead projector is not working, try to push the button more slowly, and you can feel the "click".

Inside the overhead projector, usually it is like a television, but the difference here is it has two mirrors. The machine has a bulb and a spare bulb. The bulb is use sends light beams to the first mirror, and the second mirror catches it, and leads it to a magnifying window at the last end of the path of light, this focuses the light to keep the data on the screen.

Overhead projectors use the play of mirrors, like a telescope, but uses mirrors to project images and documents.

Overhead projector basically functions well because of the fan and a bright lamp inside the machine. If you notice, overhead projectors have a special long overhead; this is used in minimizing or maximizing the use of Overhead projector.

Transparencies are placed on top of the second mirror, and when the lights are put on, it immediately projected at the screen of the lecturer. The light of the lamp travels between the two mirrors; the second mirror eventually reflects the transparency with information.

An overhead projector can function very well, if the knobs are all in place, especially the plastic ones. Most overhead projectors are kept firmly in box type cases to protect the bulbs and other parts from malfunctioning.

The lens used in overhead projector is called the "fresnel lens", the concept here is the optic works of a microscope and telescope. These lens are circular and focuses the light in one direction, here to an area of a reflecting mirror, then this mirror reflects the document on screen.

The lens used in overhead projector is called the "fresnel lens", the concept here is the optic works of a microscope and telescope. These lens are circular and focuses the light in one direction, here to an area of a reflecting mirror, then this mirror reflects the document on screen.

The optics of the lenses usually inverts the images; if it doesn't there is a need of another lens. The lenses has a thick middle and the edges are thinner, or basically it is known as convex lenses.

The bigger lens called objective lens is nearer the object, and makes it a smaller image in the scope, the picture or image is too small so the need of the eyepiece which will make it into a bigger image. There is a focal length on each lense on lenses. The formation of the image in different lenses, in such away that is is form away from the lenses.

Source : TechFaq

Ominto

Thank you for posting this information!)

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