One of the most important components in a projector is the light source. The choice of light source highly impacts cost, performance, and service requirements. Today, most projectors are using a true solid-state light source such as LED or laser, which gives a lot of benefits compared to the still-common laser phosphor projector with its spinning color and phosphor wheels. But what is solid-state, and what is true solid-state?
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 laser phosphor, pure RGB laser, and LED.
- What is NXL™?
- What are the benefits of a solid-state light source?
Solid-state vs. true 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 projector that depends on spinning mechanical components such as a color wheel or phosphor wheel is not considered true solid-state, even when the underlying laser source is based on sime-conductors.
A true solid-state light source is generally more rugged and provides a longer lifespan and reduced need for maintenance. It also provides benefits such as a wide and saturated color gamut, and in pure RGB laser projectors, offering impressive brightness levels and long lifetime. These are benefits that are all appreciated in professional applications, such as simulator systems, control rooms, planetariums, dark rides and any other application with strict uptime 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, laser phosphor has become the most widely deployed light source in professional projection. We will take a closer look at laser phosphor, pure RGB laser, and LED in this part.
Laser phosphor with color wheel: the standard comparison
In professional projection today, laser phosphor is the most widely deployed technology. A typical design uses a cluster of blue lasers to excite a yellow phosphor coating on a spinning wheel, generating the green and amber/yellow light needed for the full color spectrum. A second spinning component, the color wheel, sequences these colors in sync with the DLP chip to produce a full-color image.
Despite using a laser as the underlying light source, this design depends on two rotating mechanical components. These components are wear items with a defined service schedule, and failure outside that schedule can cause unplanned downtime.
The main limitations of a laser phosphor projector with a color wheel include:
- Scheduled maintenance: The color wheel and phosphor wheel have a service interval and require eventual replacement, adding to the total cost of ownership over the product’s operating life.
- Color artifacts: The spinning color wheel introduces sequential color, which some viewers perceive as a brief rainbow effect on fast-moving content.
- Restricted color gamut: Phosphor conversion limits the achievable color volume. A laser phosphor projector cannot match the color performance of a direct LED or pure RGB laser light source.
- Frame rate constraints: Most laser phosphor designs use a 1-chip DLP system where the color wheel limits the maximum achievable frame rate, a critical limitation for high-frame-rate simulation and visualization applications.
What is an 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 true solid-state technology, you can find projectors producing up to 6,700 lumens using the high-lumen-density NXL(TM) module from Norxe.
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 50,000 hours before service and the LED light source has a lifespan of 100,000 hours or even more.
Combining LED with DLP™ projection systems, LEDs enabled the projector manufacturers to remove the color wheels, eliminating a weakness in 1DLP projectors.
What is a pure RGB laser light source?
A pure RGB laser light source uses individual red, green, and blue lasers as the sole light source, with no phosphor conversion and no color wheel. It is fully solid-state. The first commercial pure RGB laser projectors were introduced in 2016, targeted at the digital cinema market. Until recently, pure RGB projectors have been very large, very bright (typically 30,000 lumens and up), and very expensive.
In 2021, Norxe introduced the P20 projector, a compact projector with a pure RGB laser light source, aimed at niche markets such as simulation, control rooms, scientific visualization, and planetariums.
NXL™
In 2021, Norxe introduced NXL™, a true solid-state light source technology. Low power consumption, long lifetime, and sustained color and brightness performance over time are all key elements. NXL is available as a light source in the P10, P55, and P60. NXL paired with LED offers equal or better color and brightness performance than the obsolete HLD/LED from Philips/Signify.
Conclusions: what are the benefits of a true solid-state projector light source?
Considering the differences between the different light sources, a true solid-state light source is a given choice. The benefits over a laser phosphor system with color wheels are covered above, but they are in short:
Longer lifespan: Lifespan from 50,000 and up to more than 100,000 hours, with no scheduled replacement of illumination components. A laser phosphor projector requires periodic color wheel and phosphor wheel maintenance throughout its operating life.
Wide color gamut: Both NXL/LED and pure RGB laser offer a significantly larger color gamut than laser phosphor light sources.
Reduced need for maintenance: No spinning components means no scheduled illumination maintenance. Downtime and maintenance due to the illumination system are practically eliminated.
Reduced cost: With no scheduled illumination component replacement, the total cost of ownership is significantly lower than that of a laser phosphor system over the product’s lifetime.
No image artifacts like rainbow effects: Without a spinning color wheel, there are no sequential color artifacts. Rainbow effects are eliminated entirely.