One of the most important components in a projector is the light source. The choice of light source highly impacts cost and service requirements. Today, many projectors are using a solid-state light source such as LED and laser, which gives a lot of benefits, compared to the more traditionally used lamps.
In this article we will cover the following topics:
- What is the definition of solid-state when it comes to projection?
- Introduction to different types of light sources, such as lamps, laser, laser phosphor and LED.
- What are the benefits of solid-state light source
What is solid-state?
Solid-state refers to electronic components, devices and systems without moving parts. For a light source such as LED, it is based on a semiconductor system. A UHP lamp that uses vaporized mercury in an arc design to create the brightness is not considered solid state.
From the Oxford dictionary:
(of a device) making use of the electronic properties of solid semiconductors (as opposed to valves).
A solid-state light source is generally more rugged and provides a longer lifespan and reduced need for maintenance, while also providing other benefits such as a wide and saturated color-gamut or in larger pure RGB laser projectors – incredible brightness levels. These are benefits that are appreciated in many applications, such as simulator systems, control rooms, planetariums, scientific visualization and with stringent up-time requirements.
What are the most common light sources in projection?
Since the introduction of mainstream laser projectors in 2016 and LED projectors some years earlier, the most common light source is still lamps. We will look at some of the different lamps, RGB laser, laser phosphor and LED in this part.
Ultra-high-performance lamp (UHP)
One of the most common lamp types is the The ultra-high-performance lamp (UHP, a trademark of Signity, a spin-off of Philips). The concept of the UHP lamp is a high-pressure mercury arc lamp that was introduced in 1994. Today, the product is more or less the same, but with incremental improvements over time (better drivers, electronics). In this lamp space, you find lamps with up to 4,000-5,000 hours’ lifespan, but these lamps are typically not used in professional projectors. A UHP lamp found in a professional projector has a lifespan of 2,000-2,500 hours and a warranty of 500 hours or 90 days. In normal use, the brightness output of the lamp is reduced to about 50% of the initial brightness after 1000-1200 hours use.
What is a LED (light-emitting diode) light source?
The light-emitting diode (LED) is a semiconductor light source. Compared to other light sources, LED has a number of advantages, including long lifetime, small size, fast on-off switching and low energy consumption.
The negative with LED compared to other light sources is that it initially had very low brightness output, and the first native LED projector in the market had no more than 400 lumens.
With recent developments in LED technology, you find projectors with up to 5,000 lumens using the high-lumen-density ColorSpark™ HLD LED technology from Signify/Philips.
LED technology is perfectly suited for heavy duty use applications, where longevity and reduced need for maintenance are critical factors. Some LED-based projectors are designed to run up to 25,000 hours before service and the LED light source has a lifespan of 50,000 hours or even more.
Combining LED with DLP™ projection systems, LEDs enabled the projector manufacturers to remove the color wheels, eliminating a weakness in the DLP one-chip projectors.
What are laser and laser phosphor light sources?
Another new light source compared to the lamps, are laser and laser phosphor light sources. A pure RGB laser light source is also solid-state. The first commercial pure RGB laser projectors were introduced in 2016, targeted at the digital cinema market. Until recently, the pure RGB projectors have been very large in size, very bright (typically 30,000 lumens and up) and very expensive.
In 2021, Norxe announced the P2 projector, a compact projector with pure RGB laser light source, aimed at niche markets such as simulation, control rooms, scientific visualisation and planetariums.
In 2021 Norxe is introducing NXL™, a new true solid state light source technology. Low power consumption, long lifetime and sustained color and brightness performance over time are all key elements. NXL™ will be available as a light source in the P1+ projectors, and in the up-and-coming 4K products P50 and P60. NXL paired with LED offers equal or better color and brightness performance than today’s HLD/LED.
What is laser phosphor?
A more affordable and more common light source than the RGB laser is laser phosphor. Many projector manufacturers have released laser phosphor projectors. They are typically designed with a cluster of blue lasers, where red and green is created from yellow phosphor (on a spinning wheel), or with red and blue laser, and yellow or green phosphor. This varies among manufacturers.
The downside for many laser phosphor projectors is the fact that they are designed with a 1-Chip DLP system, so there are moving parts in the projection system even if the laser itself is solid state. They also use a color wheel that causes rainbow and color artifacts.
What is a true RGB laser light source?
A true RGB laser light source is exactly that. The light is created by red, blue and green lasers – and only lasers. With a pure (or true) RGB laser light source, you get all the benefits of the laser, and none of the negative effects a laser phosphor design gives.
Conclusions – what are the benefits of a solid state projector light source?
Considering the differences between the different light sources, a solid state light source is a given choice. The benefits of a solid state lighting system is already mentioned, but here they are in a short format:
- Long life span: Life span from 20,000 and up to more than 50,000 hours, compared to the 2-2,500 hours in a lamp.
- Wide color gamut: Both LED and pure RGB laser offer a significantly larger color gamut than traditional lamps as well as laser phosphor light sources.
- Reduced need for maintenance: Do the math. With a life span that is at least 10 times as long as a lamp, downtime and maintenance due to the light source is virtually eliminated.
- Reduced cost: With almost no need for maintenance, there is no operating cost compared to a lamp based system.
- No limitations on projector installation: All lamps have a limitation on orientation. If mounted wrong, the lamps will burn out much faster. With solid state light sources you can mount the projector any angle you want – in any orientation.
- No image artefacts like rainbow effects: As there is no need for a colour wheel to create the colors on screen as in a 1-chip DLP system, you eliminate these artefacts 100%.
CTA: If you are interested in other important factors to consider when selecting a projector for your simulation system, have a look at our free Checklist.