What is Projector- Definition, Types & Uses

Definition of Projector, What is Projector, Types of Projector, Uses of Projector, How does a Projector work, Who invented Projector

What is Projector? All of you might have seen projector being used in your class, or in any government function. Now a days people use projector in weddings too, to refresh old memories. But do you know what is this video projector? If you know the simple answer to all these questions, then read this article. Because today we are going to share all the information about projector with you.

Now those days are gone when blackboards used to be installed in the classrooms, in which they are filled with quotation, maths equation and science diagrams. Teachers were required to write repeatedly using chalks to explain a concept. Sometimes not all things can we explain properly in these blackboards. In such a situation, by using digital projector, teachers can easily concentrate and explain all the concept to the students better. With this, teachers can now teach student seamlessly without using any chalks which used to waist a lot of time earlier. By getting more time students can ask all their doubts. So today I thought that why not you should be given information about what is a projector, so that it will be easy for you to understand it.


What is Projector?

A projector is an optical device that projects an image or moving image onto a surface which is primarily a projection screen. The most common type of projector in today’s time is the video projector. Video projectors can be called digital replacement of earlier types of projector such as slide projectors and overhead projectors. (Database)

Who invented Projector?

It was invented by Charles Francis Jenkins in 1894. There is no similarity between today’s projectors and old projectors, where in the earlier original models light was blasted through celluloid film and images and sounds were stringed together using some such techniques which are not even used anywhere. There is a lot of complexity in both the design and implementation of modern projectors. Many different core technology are used in it which provides a wide range to perspective buyer.

Types of Projector

There are many types of projectors but three of them are the most important.

1. DLP
2. LCD
3. CRT

1. DLP

This technology is based on an optical semiconductor called a DMD chip (Digital Micro Mirror Device). It was done by Texas Instrument in 1987. A DMD chip is made of millions of tiny mirrors, which rotate in 10 degrees angle (in better models it is also 12 degree). In a DMD chip shaders are often additional and are controlled using shader controls. These are such controls in which they rotate in a complete round, which can range from about 150× each second to 250× or even more. Many affordable products can be made using several message shade controls. It can be any colour either Red/Green/Blue, but often it is a clear message.

What are the advantages of DLP projector?

(a) It has Filter-free design.
(b) These are sealed projection systems.
(c) There are no problems of failed air filter in it.
(d) There are higher contrasts.
(e) Less pixilation occurs.
(f) It is lighter and smaller.

What are the disadvantages of DLP projector?

Rainbow effect can be seen in it. Colour will sometimes produced rainbow effect. Rainbow effect also called colour separation artifects. These are momentary flashes of banded colour that look completely like rainbows. They occur randomly and they only last for a few moments. This problem mostly appears in slower colour wheel projectors. The rainbow artifects problem never appear in 3- DLP chip projectors because 3- single DLP chips technology is used in it.

2. LCD

It is a type of video projector that is used for displaying video images and computer data on a screen or other flat surface. This is the modern version of slide projector or overhead projector. To display images LCD (liquid crystal display) projectors typically send light from a metal halide lamp through a prism or a series of dichroic filters that separate that light into three poly silicone panels- in which firsr for red, second for green and third for blue components of video signal.

Because polarized light passes through these panels (which are a combination of polarizer LCD panel and analyser). Individual pixels can be open to allow light in our close to block light. This combination of open and closed pixels can produce a wide range of colours and sheets in the projected image.

What are the advantages of LCD?

(a) Higher contrast ratio is in specific projector models.
(b) Sharper image is in specific projector models.

What are the disadvantages of LCD?

(a) Having a low contrast ratio, due to the design of the equipment, in which there equipped with high-quality optics.
(b) These are high weight.
(c) Dust blocks are impurities in panel. That’s why the LCD structure projector must be cleaned after every 300 hours of use.
(d) Color decay happens.
(e) Limited lifetime screen-door effect is visible in this. This happens when the lines between the pixel become visible due to which separate pixel become visible and these effects becoming more distracting.
(f) Dust issues are very high. Due to this dust accumulation, there can be a decrease in contrast ratio up to 50% over time
(g) These have dead pixels which you must heard of already in LCD monitors.

3. CRT

The full form of CRT is “Cathode Ray Tube”. This is the biggest and most used projector. Many of you must have seen this projector in the auditorium of the school, or in the bus CRT utilisation tubes, which are also called “guns”. These three colours combine and converts to form an image. CRTs do not have a fixed number of pixels, which makes them versatile machines capable of producing clean image from higher to lower resolution sources. Operating CRTs requires periodic calibration by a trained professionals which is an additional expense for the end user.

These projectors are generally fixed installations due to their size. CRTs are not as bright as other technologies, but the refined picture quality that a properly calibrated CRT provides hard beat. Wherein its part are more costly, specially for those guns have to spend a lot of money to replace them.

What are Projection Screens?

A projection screen is the screen where the installation consist of a surface and a support structure, which is used to display a projected image that is ultimately seen by the audience. Projection screens are either install permanently, such as in a movie theatre or semi permanent, such as in a conference room. There are many varieties of projection screen such as digital, movie, screen, overhead etc.

But the basic idea in all the screen is same which is- front projection screens work by diffusely reflecting the light that is projected onto it, while back projection screens work by diffusing the light by transmitting in them.


1. What is Projector?
Ans. A projector is an optical device that projects an image or moving image onto a surface.

2. Who invented Projector?
Ans. It was invented by Charles Francis Jenkins in 1894.

3. What is the type of Projector?
Ans. There are three types of projector-  LCD, CRT, DLP. 

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