LED Projectors

LED's or Light Emitting Diodes have been around since 1962. Originally used for indication purposes rather than illumination. The latest development to high power created the small pocket portable projector market. Using Red, Green and Blue (RGB) solid state LED's they produce a brightness from 40 to 1500 Lumens and are suitable for small screen projections.

Small compact and portable with battery power. RBG LED projectors are still substantially below the 2500 minimum required by most business professionals. Their limitation is the Green LED's not being able to produce as much light as the Red and Blue. To increase the brightness to this level manufacturers had to develop a Hybrid Laser/LED powered system.

 

3 LED Light Engine

 

This Casio Hybrid system replaced the Green LED with a Laser, these were the first mass produced laser projectors on the market. Green Lasers were also too weak to produce enough light, so a blue laser sent through a green phosphor filter. This system has now been adopted by most manufacturers and has increased the light output substantially and took LED projectors into the mainstream market.

Their more robust light source can take more knocks than Tyson Fury. Offering 24/7 operation with low maintenance costs. With no need to let the lamp heat up or cool down, they can be turned on or off instantly.

 

Hybrid Laser/LED Light Engine developed by Casio

 

Durability

The latest independent consumer watchdog research published in the UK Daily Mail newspaper (open pdf) found more than a quarter of LED lamps did not reach their quoted life of 15000 hours. Some even fail to reach 6000 Hours. 66 out of 230 samples failed before 10000 hours. These LED lamps are the same technology used in the LED projectors.

Life Expectancy

When the unit stops working there are no replacement lamps are available and it will need to be replaced. In comparison a lamped projector, can have a new lamp added when required.

Brightness

The truth is that brightness drops off with all light sources. When you reach the quoted lifespan, brightness is at 50%.

A number of LED projectors have had issues in producing consistent brightness. A range of high lumen machines had to be discontinued because lumens would vary with each power on. Varying from 3500 lumens to 2000 lumens. This does now seem to be in the past.

 

LED brightness over time

 

A lamp produces all three colours, as it ages they drop off evenly. If you have three light sources, each will degrade at different rate. If you see the graphs below you will see this is true for LED. The colour brightness changes with time and the spectrum reduces. As the graphs below show the coloured LED's used in projectors deteriorate at different rates - Red dropping to between 94%-86% after just 2000 hours?

Note: each graph displays the results for three different LED manufacturers