CRT vs. Digital Projectors

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Projection technology has come a long way. We went from projectors of the pre-computer era to the digital projectors we use today. 

Slide and overhead and CRT projectors were some of the earliest projectors ever used. They could project transparencies, slides, and still images. 

However, they had shortcomings when it came to projecting videos. The development of digital projectors was a great step in solving that problem.

You’re probably wondering what CRT and digital projectors mean, how they work, and which is better. 

This article will provide answers to your questions.

What is a CRT Projector?

A CRT (Cathode Ray Tube) projector is a projector that generates images with the aid of a small, high-brightness cathode ray tube.

The first CRT color projector was released in the 1950s. For most of the 20th century, CRT projection technology was employed exclusively.

It was the standard for video technology until flat panel solutions like Digital Light Processing (DLP) began to take over the market.

How Do CRT Projectors Work?

A cathode-ray tube primarily comprises three electron guns in a vacuum. The vacuum is sealed by a glass tube. 

The inside and outside surfaces of the glass tube are coated with lead. This is to protect it from breakage and electromagnetic radiation.

The three guns represent each of the primary colors: red, green, and blue. 

CRT projectors usually make use of three different tubes. Each one is fitted with a lens to magnify the image being generated.

Electrons are fired from the electron guns through the vacuum in the tube, towards the front of the tube, which is coated in phosphor. 

The result is a video image being “painted” from top-to-bottom and side to side at a very fast rate.

After the image generation, the lenses situated in front of the CRT are used to focus and enlarge the video image onto a projector screen.

Due to the magnification and separation level, you have to ensure that the video image is properly focused. You can do the calibration yourself, or have a technician do it during setup.

What are Digital Projectors?

Digital projectors are modern-day devices that project digital images from any digital media source i.e. computers. 

Digital projectors may use one of the following technologies: DLP, 3-DLP, LCD, or LCoS. 

DLP and 3-DLP projectors are considered the ‘true’ digital projectors. This is because they use DLP technology and chips. 

DLP technology is modern, and it caters well to ease and portability. Some of its characteristics are a sharp image and a fast response time.

How Do Digital Projectors Work

We have said that any projector that can connect to a computer is a digital projector. For this article, we will focus on projectors that generate images using the DLP technology. 

Digital Light Processing (DLP) consists of chips that are also referred to as digital micromirror devices.

The digital micromirror devices (DMD) consist of millions of tiny mirrors, arranged in a matrix, on a semiconductor chip.

Each micromirror represents one pixel of the image being projected. This means that the image resolution is the same as the number of mirrors used during projection.

Images are formed when light falls onto the DLP chip. The micromirrors send the beams to or away from the projector lens. 

The mirrors can be repositioned very rapidly. In the ON position, they reflect light through the lens (towards the screen), but in the OFF position, they deflect light onto a heat sink (away from the screen).

DLP projectors work with one of two methods to produce colored images:

• Single-chip DLP, and
• the 3-chip DLP

Single-chip DLP projectors produce color images by putting a color wheel between the light source and the DLP chip. 

3-chip DLP projectors use a prism to split the light from the light source. The result is three primary colors.

The red, blue, and green colors are sent to individual chips and rejoined to produce the full image.

Which is Better: CRT Projectors Vs. Digital Projectors

CRT and digital projectors perform differently in various aspects. They have different degrees of brightness, longevity, and other features. 

We will make a comparison of both kinds of projectors based on select parameters. In the end, it should be easy to decide which is best. 

1. Power Consumption

The power consumption of a projector is determined by its features, the projection mode used, and the brightness of its lamp.

DLP projectors consume more power than other digital projection technologies. The average power consumption of a DLP projector ranges between 150W to 350W.

However, a DLP projector is not to be compared to CRT projectors in that regard. 

CRT projection technology is old and has a high power consumption. The power consumption can be up to 500W per hour. 

Running a CRT projector for extended periods can cause a hike in your electricity bill.

2. Size

Portability is an important feature now because people want to take their devices anywhere and use them on the go. 

The size of a projector depends on its parts. Over time, we have gone from large and heavy devices to sleek, portable devices. 

CRT projectors are older technology. They are bulkier and have larger parts than DLP projectors. CRT projectors can weigh up to 250 lbs.

DLP projectors are more lightweight. Portable ones weigh as little as 3 lbs. while some others weigh above 10 to 50 lbs.

3. Lifespan

The lifespan of a projector depends on its parts and how fast they wear out. The most important part is the projector light source.

Typically, DLP projectors with replaceable lamp bulbs have a lifespan between 2000 – 5000 hours. However, there are other lamp-free light sources.

Pure LED lamps can last above 30,000 hours while LED/laser hybrid lamps have an effective lifespan of up to 20,000 hours. 

To maintain projection quality, replaceable lamps should be changed after their effective lifespan has passed.

CRT projectors make use of the cathode ray tube, which lasts about 10,000 hours. The phosphor surface in front of the tube is what wears out, not the electron gun.

4. Light Output

The brightness of a projector is determined by the light output of the lamp while projecting an image.

If a projector is not bright enough, the image formed on the screen will not be clear. The brightness of a projector is measured in lumens.

For a DLP projector, the brightness typically ranges between 2,000 to 5,000 lumens. 

This level of brightness is great for rooms with controlled lighting. It creates a cinema-like viewing experience.

CRT projectors are not as bright as their digital DLP or LCD counterparts. However, they do not lose brightness or color accuracy over time. 

The brightest CRT projectors have a brightness ranging from 1500 to 2000 ANSI lumens.

5. How They Work

The technologies employed for image generation differ for the different types of projectors. 

CRT projectors use the cathode ray tube technology that consists of an electron gun firing electrons through a vacuum. 

DLP projectors use digital light processing technology that consists of semiconductor chips. The chips contain micromirrors that each represent one pixel on the projected image.

The mirrors coupled with the light source reflect digital images onto the projector screen.

6. Cost

Generally, newer technology is in higher demand and of greater value. DLP projectors come with different specifications and prices, some more affordable than others. 

It is hard to find a new CRT projector these days because they are no longer being manufactured. 

However, used CRT projectors are available on the market. They are also generally less expensive than DLP projectors.

7. Noise

One major complaint in projector reviews is the noise. The noise is often a product of their cooling systems. 

The technology for DLP makes it susceptible to overheating. DLP projectors are noisy due to their use of cooling fans.

CRT projectors, on the other hand, are known to run completely quiet. They do not require an internal cooling system. 

Some come with fans and cooling systems, but can easily be modified to produce less noise. This is why they are still popular in movie theaters. 

8. Rainbow Effect

This is a hitch that happens in some projectors that generate color with a color wheel. Some people see color flashing in sequence on the projected image. 

Single-chip DLP projectors usually show this effect. 

The color wheel spins very fast so that the different colors are unnoticeable. However, older DLP projectors may have slower or faulty color wheels, resulting in the rainbow effect.

The rainbow effect does not occur in CRT projectors. Users are safe from the discomfort and eye strain it causes. 

Final Recount

CRT projectors have held their own against the newer digital projectors. However, DLP technology offers obvious advantages. 

CRT projectors have excellent black levels and zero motion blur. This makes them excellent choices for edge blending setups. 

Their considerable lifespan gives them a fighting chance against newer technologies. They can be used for more than 10,000 hours, depending on the contrast setting in use.

DLP projectors are relatively easier to operate and set up. They are lightweight, brighter, and offer great contrast. 

They have portable designs and this makes them convenient and easy choices in today’s world. 

Table: Advantages and Disadvantages of CRT Projectors

FAQ

Are CRT projectors good?

CRT projectors have been around for a long time.  

One thing you cannot ignore about them is their size. Their large picture tubes and lenses account for most of their weight. 

There’s much misinformation surrounding CRT projectors. Many people think they have short lifespans and cost a fortune. 

However, CRT projectors are quite affordable and they project images in high quality. Many of them can project images from digital sources. 

Yes, CRT projectors are good. If you aren’t looking for a portable, low-maintenance projector, then CRTs are an option. 

Conclusion

The comparison between CRT and DLP projectors pitches the old vs. the new in projection technology.

Both projectors utilize different technologies, but they serve the same function.

Choosing the better projector isn’t a clear-cut decision. It depends on your needs, budget, and how you intend to use it.

Although DLPs are more common, several people still own CRT projectors. If you can look past its limitations compared to more modern projectors, a CRT projector in healthy condition can be of good use to you.

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