What is a Projector and How does it Work?

What is a Projector

What is a Projector? You must have seen projectors, they are used to display videos on the big screen while studying in class or at weddings. Projectors are also used in cinema halls to show movies on the big screen. But have you ever wondered what a projector is and how it works?

A projector is an optical device that projects an image or video onto a surface called a projection screen. In today’s article, you will learn about all the information related to the projector, where the projector works, the type and benefits of the projector and who invented the projector etc. will be told. So let’s go ahead and know the complete information related to the projector.

What is a Projector?

A projector is an output device that takes images made of a computer or Blu-ray player and reproduces them on a screen, wall, or surface via projection. The projector can present static images (slides) or moving images (videos).

Mostly, the surface on which the video is projected is large, flat, and light in color. Usually the size of the projector is as much as a toaster (toast baker) and is very small weight. Using this, we can watch movies or slides with everyone on the big screen in a room.

How does the Projector Work?

Projectors use different techniques to create an image. But one thing all projectors have in common is that they use light to create images.

These devices use a light beam to present your favorite picture, movie or other visual materials in high quality. A projection screen is used to present images created through the projector that provides life-sized images. For this reason, projectors are used more in theaters.

The projector can recreate visible content from many sources, such as movies, DVD recordings, computers, and other digital sources.

Parts of Projector

Projectors come with multiple parts that rely entirely on projection technology. Overhead projectors are the most common projectors that are easily available. These are analog devices that do not include any.1
electronic parts.

The main parts of the Overhead Projector are as follows:

  • Lamp
  • Reflector and Mirror
  • Fresnel Lens
  • Arm
  • Head
  • Cooling Fan

Modern technology is used in digital projectors. They come with separate parts that include some smart parts.

Some of the parts included in digital projector are as follows:

Color Wheel and Color Filter – They are used in digital projectors. They work to add color to the white light of light.

Prism – Prism consists of dichroic mirrors that filter white light. They reflect colored light, Such as red, green and blue. At the same time, mirrors are used to recombine (recombine) light beams when they are inverted.

DMD Chip and LCD Panel – These are the most important parts of DLP and LCD projectors. These include microscopic mirrors. These mirrors reflect or deflect colored light to create an image. The projector gives better quality images through LCD panels or DMD chips.

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Types of Projectors?

There are several types of projectors. Some of these are analog and some are digital, some of which are as follows:

  1. LCD Projectors
  2. DLP Projectors
  3. CRT Projectors
  4. Overhead Projectors
  5. Interactive Projectors

1. LCD Projectors

In LCD projectors, a strong white light beam is released from the light source. This ray passes through a group of mirrors. This group consists of two dichroic mirrors coated with a particular film. Therefore, they reflect only a particular wavelength of light. Here the principle of prism is applied.

What is a Projector

Each dichroic mirror breaks down a specified wavelength. When white light hits mirrors, each mirror reflects a colored light through a projector, and then red, green, and blue light beams are generated.

Three different light rays of red, green and blue pass through three different LCD displays. These LCD displays are exactly like mobile displays, but they are transparent so that the rays of light pass easily.

In all three LCD displays, the same picture is displayed at the same time. When colored light passes through these screens they offer three different versions of the same scene: red, one green and one blue.

Inside the LCD projector, these three-color versions are recombined through a dichroic prism and a single image is created. Now this image contains not three but millions of colors.

Finally this vibrant, colorful version of the scene is passed through a projector lens and displayed on the large screen.

2. DLP Projectors

DLP projectors are a new technology first developed by Texas Instruments in 1987. This technique is called digital light processing technology. It uses a microchip that has close to 2 million tiny mirrors.

Mirrors on the DMD (Digital Micromirror Device) chip are tilted in the position off or on. The inclination of each mirror is determined through an electronic circuit.

What is a Projector

They reflect light of any color in the on-the-spot position. In off positions, they deflecate light beyond the lens.

In the off position, the dark part of the picture or movie appears on the screen. A color wheel is placed on the path of the light beam, due to which red, blue and green rays are received.

When colored light falls on the DMD chip, its mirrors reflect the light on the screen through the projector’s lens. The images created from it are made in different colors but it switches very fast. Human eyes see this RGB variations as a colorful image.

DLP is a three-chip variant of projectors. Each of these has a separate chip for RGB color and colored wheels are not used. In these, white light is passed by a prism, and it is divided into three colors: Red, blue and green. Now these colored lights go to their own chip.

Mirrors reflect colored light through a prism that combines the lights coming from all three chips. When combined light passes through the lens, it is projected as a single colorful picture on the screen.

DLP projection has higher color accuracy because it has more pixels. These are portable and cheaper than LCDs.

3. CRT Projectors

CRT projectors are slightly larger in size, making them less popular. A CATHode Ray Tube is used inside a CRT projector. This tube creates images with high brightness.

What is a Projector

The image created is processed from three different CRT tubes. Each tube is for a particular color, including red, green, and blue.

There is also a lens in the front of these tubes which enlarges the image. This lens focuses on images, enlarges them and projects them onto the screen.

CRTs are known for superb picture quality. These are more advanced and can accept data from HDMI (High Definition Multimedia Interface) sources. These are durable. Most of these lamps can burn for about 10,000 hours. These do not lose brightness like DLP and LCD projectors.

But they consume more energy, so they are not suitable for use at home.

4. Overhead Projectors

Overhead projectors are very simple projectors. They use light to create the image that is passed through the film. The content to be projected onto the film can be written, created or printed. Apart from this, you can also use other transparent materials.

What is a Projector

Mirrors and lenses are used in overhead projectors. These help to flip and enlarge images. In this, light passes through transparency and creates an image. Converging lenses are used to ensure that the light goes towards the mirror properly.

Mirror reflects the light. Naturally reflected beams are reversed. This ensures that the picture is not projected from the back. Flipped light beams pass through an objective lens that helps to enlarge the image.

This kind of projection is used more in the classroom. Apart from this, it is also used for formal presentation. Overhead projectors are very useful for large texts, technical diagrams and other materials that do not require much color detail.

They do not require much repair because they do not have moving parts and maintenance is very easy.

5. Interactive Projectors

What is a Projector

Interactive projectors are highly advanced devices. These are usually Ultra Short Throw (UST) projectors. They project visual data to the same screen as regular projectors. But there is a difference between them.

In these, you can interact with projection. This is possible by using special pens and sensors. Using a pen, you can make changes to the projected image. You can create or write something on the image, and the projector can record these changes.

Interactive Projector Works in Two Ways.

DLP Interactive Projection – DLP interaction involves a special technique. Interactive DLP projectors project their own patterns onto your image screen. Pen detects these patterns. The projector also uses patterns to detect the movement of the pen. The projector understands the information received and completes the necessary changes to the image.

Infrared Interactive Projection – Infrared interaction is quite simple. These projectors have a camera installed. This camera detects when you use an interactive pen. Pen detects infrared light on the screen and changes the image.

Sources of Light for Projection

Projection technology is not possible without light. Pictures and movies are made and projected using light. Different light sources are used in different projectors. Lamp bulbs are used in older projectors.

Modern and digital projectors now use longer light sources. LeDs, lasers or a combination of both are used in them.

Light sources used for projectors include:

  1. Lamp Bulb
  2. Laser Light
  3. LED

1. Lamp Bulbs – These are glass bulbs in which mercury is used. They are easier to replace and are less expensive. But their life is short and the brightness also decreases with time.

2. Laser Light – This is a strong beam of blue color. Its strength increases the quality and contrast of the picture. Projectors with lasers are more bright. The price of this light is high. However, laser projectors require less maintenance. The quality of light output is also not reduced in them.

3. LED – LED is the more durable light source. Their lamp life is 20 thousand hours or more. Different LEDs produce different types of light. There is no need to split the white light in it.

LEDs are not as bright as lasers. However, they are small, lightweight and convenient to create portable projectors.

Who Invented the Projector?

The first movie projector was the Zoopraxiscope, invented in 1879 by British photographer Eadweard Muybridge. To create motion, zoopraxiscope used to project images rapidly with the help of a rotation glass disk.

But the first successful movie projector was invented by the Lumiere Brothers, which was based on french inventor Leon Bouly’s Cinematograph Projector. It included a film camera, projector and a printer. The brothers’ first film was La Sortie De I’Usine Lumiere a Lyon, which was filmed in 1894 and released in 1895. The film was projected on a screen of 16 x 21 meters by the Lumiere Brothers at the Paris Expo.

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What are the Uses of Projectors?

  • Projectors are used to teach children in classrooms. Through this, diagrams, charts or other materials that make learning easier can be projected.
  • They can be used in business. In most businesses, projectors are used to show ads to customers. Restaurant menus, news, calendars, and other information are shown on digital signage.
  • The projector can be used for entertainment at home. They can be used instead of TVs. Through these, movies, TV serials and games can be enjoyed on the big screen.
  • Projectors can be used during outdoor activities, such as cinema trips, camping, and drive-ins. Large and bright images can be created for the audience through the projector.
  • Projectors are also used for art projection. Artists are always trying to recreate art on different surfaces. Pictures can be enlarged with the help of projection. This gives the artist a chance to recreate the picture on a large scale.
  • Projection is used during a meeting or conference. The projector helps to share information, ideas and plans with the company’s employees.

Advantages of Projector

  • Large image – The projector helps to project large images. Even at home, a projector can provide us with a cinema size screen of up to 120″.
  • Convenient and multiple properties – Due to front projection, you can project the image on any angle. Like projection mapping, pictures can also be made on sand.
  • Less space required – You can get projection at any location with the help of projector. Projection technology enables smaller size of projectors. Projectors can be made of large sizes and small sizes that weigh less than 5lbs, which are portable. They occupy very little space.
  • Easy to install – many projectors are light weight. They are easy to unbox and set up. They are accompanied by manuals that can be installed and used by looking at them. You need to mount the projector and screen.
  • They are cheap – Projectors are more economical than TVs. A flat screen HDTV can cost more than a projector, while the projector can give a larger image than a TV with the same picture quality.

Disadvantages of the Projector

  • Projectors require regular maintenance such as cleaning and replacement of parts.
  • A separate sound system is required for the projector. Because not all projectors are able to process audio.
  • The larger the unit, the higher the cost of installation.
  • Dark room is needed for good projection. Therefore, the surrounding environment can disrupt the front projection.


I hope you liked my article “What is a Projector and How It Works”. I have tried my best to explain every information related to Projector in simple terms so that you do not need to go to any other website regarding this topic. If you liked this information or got to learn something new, please share it on other social media networks like WhatsApp, Facebook, Telegram etc.

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