The Comprehensive Guide to How Different Projectors Work

15 September 2023 by
Yammy Kong

Projectors are a great tool for teaching, viewing movies, or sharing memories with friends and family. How does a projector work?

Throughout the years there have been several types of projectors and each one works a little differently, but they all have a similar outcome in that they use light to project an image on a screen or wall. Capture has been dedicated to helping families share and preserve memories for over 20 years, which is why we put together this comprehensive guide to how projectors work.

Keep reading to learn about the different components of a projector and how they work together to display images, the advantages and disadvantages of projectors, how to maintain your projector, and all the different types of projectors including LCD, LED, Laser, Pico, slide, and others so you can decide on the best option for your purposes. 

How do Projectors Work?

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While different types of projectors may have slight differences in the way they work, they all utilise the same basic premise and components. Basically, a projector shines a light through a digital image, slide, film, or screen to magnify the display onto a projection screen. 

There are a few different parts that are found in almost all projector types. First, most modern projectors use mirrors to reflect the image in front of the lens. However, the type of mirrors and the way they are used can vary greatly depending on the type. 

Projectors all have a lens that magnifies the image and will determine how far the image is thrown onto a projector screen. To use the lens, projectors need a light source that shines onto mirrors or prisms that reflect the light through the lens and onto a projector screen. 

Xenon light bulbs are the most common type of light source in movie theatre projector technology today because they offer bright light illumination for as long as 6,000 hours. For home theatre projectors and digital projectors, metal halide, halogen, and UHP are the most common types due to their high lumens and affordability. 

Finally, for digital projectors to display a colour image, the beam of light needs to combine red, blue, and green light, or RGB, light. The most common way to do this is using a colour wheel, but depending on the type of projector, different colours can be created with chips.

The Different Types of Projectors

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While each projector uses an ambient light source and lens, the way they create the image can vary greatly. That’s why it’s important to look at how a movie projector works depending on the type of projector, which will give you more information to decide on the best projector for your purposes.

1. LCD Projectors

LCD projectors, or liquid crystal display projectors, use three panels made out of glass and liquid crystal as well as three standard mirrors and two dichroic mirrors. LCD projectors work by passing white light through the dichroic mirrors that reflect onto one wavelength to split the colours into red, green, and blue light. These colours are reflected onto the three LCD panels composed of thousands of tiny pixels to bring them back together into a single image. 

The result is the ability to produce millions of colours out of RGB that offers exceptional colour saturation. LCD projectors are known for their brightness and high-quality images at an affordable price. However, they can be a little harder to maintain and are bulkier than some newer projector technology. 

2. DLP Projectors

Digital light processing projectors, or DLP projectors, were developed in the 1980s by Texas Instruments and can produce 35 million colours, which is more than the human eye. They use digital micromirror device (DMD ) chips that are made of millions of tiny micromirrors. The higher the number of micromirrors in the chip, the higher the pixels and the better the viewing experience. 

They also use a colour wheel to reflect white light onto the chips and the tiny mirrors blend the colours depending on the video or image source. DLP projectors are more expensive but produce high-quality images and superior picture quality. They are also light, reliable, and portable. 

3. CRT Projectors

Cathode ray tube projectors, or CRT projectors, are also known as gun projectors and are the oldest type of screen projectors. They use the same technology as CRT TVs and generate images with a magnifying lens and three cathode ray tubes organised like RGB traffic lights. These lights will combine on a phosphor-coated surface to produce the image. 

While CRT projectors may not produce a high-definition projected image, they are typically known for being durable, long-lasting, and affordable. However, they will not work for ultra-short throw purposes, which means you don’t want to get them for a small conference room. If you have a big screen size, though, they are worth a shot. 

4. LED Projectors

LED projectors can be a type of LCD or DLP projector, but they use light-emitting diodes, or LEDs, to produce the light instead of traditional projector lamps or light bulbs. Other than that, an LED projector will still have to use the same technology as a DLP or LCD projector.

5.  Laser Projectors

Similar to LED projectors, the term laser projector refers to the light source, not the projector technology. Instead of using a light bulb or LED lights, a laser projector will use a laser. Then, they can use DLP, LCD, or LCOS technology.

6.  LCOS Projectors

Liquid crystal on silicon or LCOS projectors are the newest type of projectors on the market. They use silicon instead of mirrors like DLP projectors. The beam of light is split into red, blue, and green using dichroic mirrors, similar to an LCD projector. The filtered lights are combined using a prism and passed through the lens and onto a screen. 

LCOS video projectors are known for offering incredible image quality and contrast ratio without producing a “rainbow effect” that’s the result of the single chip or spinning colour wheel found in other types. In fact, most 4K home theatre projectors use LCOS technology. However, some people still prefer DLP projectors for fast motion videos because of the potential blur. 

7. Pico Projectors

Pico projectors are mini or micro projectors. They are light, portable, and compact, which means you can take them anywhere. While they can work okay in a very dark room as short-throw projectors and are certainly nifty gadgets, they are limited in well-lit areas, outdoors, or for big screen viewing. Furthermore, the built-in batteries can die fast, but some plug into an HDMI or USB for longer life.

8. Slide and Film Projectors

Finally, there are the traditional slide and film projectors that project light directly through your memories. While generally replaced by the other types of projectors, these will be the only type you can use to view your precious analogue memories. They are fun and affordable, but harder to maintain. If you plan on using a slide or film projector, we recommend converting your memories to digital first just to make sure they are never lost.

Advantages and Disadvantages of Projectors

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Projectors offer some distinct advantages, but there are also disadvantages to consider, particularly with some projector types. By weighing your pros and cons, you should be able to choose the best projector for your needs whether you plan on using it to teach, watch movies, or view precious family memories.

Benefits of Using Projectors

One of the main advantages of projectors is customisable screen size, which means you can use them to view in a small or large area depending on what you’re using it for. Additionally, they are compact and easy to travel with compared to televisions. 

Many people also find that a home theatre projector is easier on the eyes than a TV. Finally, they are typically affordable, easy to maintain, and produce a high-resolution final image. Many even offer focusing and lens interchangeability depending on your specific needs. 

Limitations of Projectors

The primary limitation is the fact that you will need to have a screen to project the image onto. To get the best results, the screen will need to be white and flat as well. Additionally, ambient light can impact the experience and it may be hard to find a very dark room to use a projector. 

Finally, not all projectors are good for all sizes and distances. Some are only designed for ultra-short throws while others are better for displaying on a big screen far from the projector location. 

Choosing the Right Projector

The main things to look for when choosing your projector are the resolution, throw distance, portability, brightness, and screen size. If you plan on displaying power points and presentations, then resolution might not be a big deal, but if you are using it to view movies or precious memories then you might want to choose a higher quality projector. 

Consider the room where you plan on using it, how much light there is, and how far from the screen you plan to place the projector. You should be able to find these types of specifications on the projector options while you are shopping at Best Buy, Amazon, Walmart, or anywhere else. In addition, some projectors have special features like zoom, wireless capability, surround sound audio, and more. 

In addition, you want to consider budget and manufacturer. While small name projectors can be cheaper and good quality, if you want something that will last, it might be good to choose one from a recognisable brand like Epson, Sony, or Canon. 

Maintaining and Caring for Your Projector

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To make sure your projector continues to work for years to come, you must take good care of it. Make sure you read the manual because some projectors have requirements for how close the walls are to the fan. Otherwise, they can overheat due to limited airflow. You should also strive to power it down anytime you aren’t using it. 

It’s best to always keep your projector clean to prevent fan clogging. When the lens is dirty it also impacts the image quality. Clean the lens regularly with a lens cloth and check the air filters every few weeks to make sure they are clear of dust and debris. 

The most common projector problem is something that will always happen but sometimes takes you off guard: a bad lamp. Most modern projectors will tell you it’s time to replace your light bulb and doing so will prevent the awkwardness of an ineffective projector. Another common issue is overheating, which means you need to double check the airflow and fan to make sure they are free from debris and not too close to surrounding walls. 

Finally, out of focus and blurry images (or even discoloured images) are other common issues that can typically be fixed by adjusting the colour settings, lighting, and focus settings on your projector. You should also try cleaning the lens and repositioning the projector closer to the screen. If these don’t work, then you may need to clean or repair certain parts. 

Based on which factors does Capture recommend projectors?

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Now that you know how a projector works with a phone, memory card, computer connection, or even analogue slides and film, you can start viewing your precious memories, movies, and more! Just make sure you consider the screen size, room size, darkness, resolution, and other factors to choose the best type for you. If you are a beginner and using it at home, Capture suggests using a mini projector, which is suitable for small-sized homes and has a short throw distance. Alternatively, you can use a budget-friendly CRT projector. If you are an advanced player and aim for higher resolution, you can use LCOS and DLP projectors.

To display your most precious photos, videotape, album, slides and more using a digital projector, choose Capture to digitise your memories. Click here to learn more about Capture’s digitisation services!

*This article is brought to you by Capture HK.

Capture HK is the premier analogue media digitisation company in Hong Kong.

Capture HK's business covers photographs, photo album digitisation, videotapes digitisation, including VHS, S-VHS, VHS-C, S-VHS-C Hi-8, Video8, Digital8, DV, DVCAM, MiniDV, DVC and digital media digitisation, including Secure Digital (SD), Smart Media (SM), MultiMediaCard (MMC) Compact Flash (CF), xD-Picture Card, Memory Stick, USB Drive, CDROM, DVD.

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