How Modern Led Projectors Work

Projectors are very important devices that we need to used from time to time. You may have never realized there are many types of projectors. They are categorized depending on more than one factor. Now, how  modern LED  projectors work?

How  LED projectors work
how do modern LED projectors work
An LED projector from BenQ

There are several methods of classifying projectors. One method is by using a light source and the second method is by considering how light and signals are processed.  When it comes to the type of light source used, there are the LASER projectors, LED projectors, and xenon lamp projectors. Light is processed in two ways in the projectors. One way is by use of the LCD screens and the second method is by use of the digital micro-mirror device. This post will answer the question that brought you here, how do modern LED projectors work?

LCD projector

I will briefly explain how modern LCD projectors work here.  A white bright light from whatever lamp you choose is projected towards dichroic mirrors. These special types of mirrors have a unique attribute that allows them to filter light so that only green, blue, and red lights are left.  There are at least three dichroic mirrors, each for each primary light color. The three primary color lights are directed towards three LCD screens; each beam is directed towards its own LCD screen.

The LCD screen is tinted only one primary color (could be green red or blue depending on the type of beam directed towards it) has pixels. The red beam is directed towards the LCD tinted red and so forth. The pixels are turned on or off by the use of a signal.  The light from the 3 LCD screen is then combined using a dichroic crystal. The final image is passed through lenses onto the final screen where you will see it.

DLP projector

Let us also take a look at how light processing projectors (DLP) work. It does not so differently from the LCD type. However, instead of using the LCD screens, DLP projectors use the digital micro-mirror device (DMD). The DMD has millions of microscopic mirrors that serve as pixels. They are as small as 5.4 micrometers. The micro-mirrors are repositioned or tilted rapidly (at a rate of 1kHz) to reflect light through a lens or onto a heat sink. To add colors to the image, a color wheel is added. DLP projectors rarely suffer the screen door effect since they are high-resolution projectors.

laser projector

Laser projector as the name suggestively describes it used LASER diodes as the source of light. There are several types of laser projectors; three laser type, two laser type, the single laser type, and the hybrid laser projector. For the three lasers, primary light colors are emitted by diodes. Each diode emits a single color which could be red, blue, or green. The primary color lights are directed towards LCD screens or digital micromirror device. Where light from lasers is reflected depends on how your projector processes light.

Two laser projectors use two blue laser light. The beam from one of the two lasers is directed to the DMD or one of the LCD screens. The other beam from the second laser is directed towards a yellow phosphorous which is excited. A bright yellow light is produced by the excited yellow phosphorous. Specialized filters are used to produce green and red light from the yellow light.

From here, the two beams (red and green) are reflected to other two LCD screens or to the DMD. Single laser projectors use one blue laser diodes.  The beam is split into two blue light beams. Now that you have two beams, the process proceeds just like when you have two lasers. Hybrid laser projectors use both LED and laser as the source of light. Now you see how high-tech laser projectors work is not very different from other projectors apart from the light source.

How modern LED projectors work

These types of projectors are not very different from the rest of the projectors. The only difference is where the light used for projection is sourced.

While other projectors use xenon lamps and laser as their light source, LED projectors use three LED light sources. One light source is green, the other one blue and the last one red.

The light from the LED lamps is reflected to either the 3 LCD or the DMD. When the beam of light hits the 3 LCD screens (each beam is directed towards one screen) it is tinted one primary color. The light from the 3 LCD screen is then combined using a dichroic crystal.

Now that discussed how modern LED projectors work, let us look into some of the advantages and disadvantaged associated with them.

 

Advantages of LED projectors
Energy saving

LED lamps do not emit a lot of heat and therefore they are cool. This means that you will not complex cooling systems used by the xenon lamp projectors here. All xenon lamp projectors have high-velocity fans for cooling purposes. However, this is not necessary for the LED. Also, most of the energy is not wasted in form of heat but is converted to light instead. LED projects are, therefore, lighter and quieter than xenon lamp projectors.

  Safer

LED projector components are hardly subjected to any thermal stress compared to the Xenon type. The assembly has reduced the likelihood of having to suffer degradation and distortion after several years of use. There are no injuries if you accidentally touch any part of the projectors since it is cool.

Extended lifecycle

LED lamps last for years before they require reinstallation. For instance, some such lamps have a life span of 30,000 hours which is three times higher than the xenon lamp type. This means you can use the projector for 20 years without changing the lamps if you use it for four hours each day.

Portability

Since LED lamps are small and do not emit a lot of heat, the LED projectors are compact. They are smaller and therefore more portable than their xenon lap type. Also, LED lamps do not need to warm up when they are turned on.  In fact, they turn to full brightness immediately after they are switched on. Additionally, you will be fascinated to know they can be turned on and off repeatedly without destroying them. They are almost impossible to break.

Disadvantages of LED projectors.

You may be wondering what are the issues associated by LED projects. The primary problem associated with how LED projectors work is the limited light output.  However, for mini projectors, this problem is hardly noticeable. After performing thorough research, I realized that the maximum brightness achievable by LED lamps in the projectors ranges between 3000-3500.

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