LEDs: A Primer
Nemalux Inc. has developed energy efficient, robust, waterproof and hazardous location approved luminaires using state-of-the-art LED technology. These luminaires take advantage of the longevity and reliability of LEDs to achieve or surpass the brightness of conventional lighting. Solar powered options are available.
These products are designed to provide industrial lighting for areas in which water, vibration, maintenance or extreme temperatures negatively affect conventional illumination. New technology LEDs offering up to 120 lumens per watt provide a replacement option to 150 watt HPS lighting. A variety of high intensity LED colours are available for specific applications.
Most of the Nemalux Inc. luminaires are designed for low voltage power. The reasons for using low voltage are:
- LEDs are inherently low voltage devices. Powering them with low voltage DC makes the system more efficient.
- Low voltage reduces cabling costs.
- Low voltage is electrically safer; there is a lower probability of arcing or sparking.
- Low voltage is ideal for solar powered applications or battery based systems.
- Using Nemalux's low voltage luminaires and state of the art power supplies we can create lighting systems which easily accommodate variations in power inputs and temperature ratings.
Quality White Light
Quality, when used to describe the white light emitted by LEDs, refers to the consistency of colour in the beam of light, correlated colour temperature (CCT) variations over time and temperature, and CCT variation between individual products.
How are white LEDs created?
There are currently two ways to make white light with LEDs. One method mixes multiple wavelengths of different LEDs to make white light (i.e. RGB), allowing the lighting designer to tune the white light to a specific colour temperature. The second method uses a blue Indium-Gallium-Nitride (InGaN) LED with a phosphor coating to create white light. This is the method that results in the more commonly seen "white LED".
Wide range of color temperatures and wavelengths (color)
Today, LEDs offer the full spectrum of white lighting from 2760K to 10,000K. Our product offering of cool-white and warm-white LEDs enable lighting designers to create lighting solutions with consistent colour temperatures.
LEDs also emit many standard monochromatic lighting colours. The Nemalux Inc. RGB luminaire can achieve any colour by combining the three primary colours of red, green and blue.
| Color | Typical λ(nm) or Color Temp (K) |
|---|---|
| Red | 625nm |
| Royal Blue | 455nm |
| Blue | 470nm |
| Cyan | 505nm |
| Amber | 590nm |
| Green | 530nm |
| Red-Orange | 617nm |
| Cool White | 5500-6500K |
| Warm White | 3300K |
High Color Rendering Index (CRI)
Colour Rendering Index or CRI is the calculated rendered colour of an object. The higher the CRI (based upon a 0-100 scale), the more natural the colours appear. Natural outdoor light has a CRI of 100. Typically high quality LEDs offer a CRI higher than 80.
Conformal Phosphor Coating Process
Uniform coating of the LED with phosphor is the most important step in creating a warm white LED. This eliminates the blue-ring effect common to other white LEDs and delivers the consistent white colour throughout the light beam.
Lumen maintenance
Lumen maintenance, usually expressed as a percentage, is simply the amount of light emitted from a source at any given time relative to the light output when the source was first measured. The materials inside a bulb will gradually deteriorate until finally the bulb will no longer emit light. This is known as the bulb's mortality (B). With conventional light sources, the bulb usually fails before our eyes notice the change in lumen maintenance.
LEDs also experience lumen depreciation but it happens over a much longer period of time, usually tens of thousands of hours.
Not all LEDs deliver the same lumen maintenance. An LED is a complex package of materials that must all work together to deliver long lifetimes. Everything from the design of the chip, thermal management, optics material, phosphors and even the assembly of the entire package will affect lumen maintenance. Some LEDs demonstrate very rapid depreciation (Fig. 1).
Figure 1. CREE LEDs vs. conventional light sources.
Lumen maintenance and lifetime are intertwined. To truly understand the lifetime of an LED light source, the user must understand both mortality (B) and lumen maintenance (L). Let's say for example you are working with LEDs that on average deliver 70% lumen maintenance at 20,000 hours (L70). You can expect to receive 70% of the relative lumens after 20,000 hours.
EDISON Retrofit LED Bulbs:
LEDs are functionally an integrated fixture/emitter "system". Nemalux Inc. typically does not advise the use of an LED Edison bulb in an existing fixture as this may affect the thermal management of the LED. Inappropriate thermal management negatively effects the lifetime and brightness of the LED.
Heat Generation:
Nemalux Inc. designs fixtures to enhance the benefits of high brightness LEDs with appropriate thermal management. New technology LEDs are not 100% electrically efficient. While most of the electrical energy is converted to light some is still converted to kinetic energy (heat).
Heat generated by solid state devices and circuitry must be dissipated to improve reliability and prevent premature failure. In the case of LEDs, heat generation effects lifetime and brightness adversely. Techniques for heat dissipation can include fans, liquid cooling and typically, for LEDs, heat sinks.
Transmission of heat from a heat source (e.g. the junction of a LED) via the heat sink into the surrounding medium takes place in four successive steps:
- Transfer from heat source to the heat sink
- Conduction from within the heat sink to its surface
- Transfer from surface into the surrounding medium by convection
- Radiation depending on the nature of the heat sink's surface
Nemalux designs fixtures to enhance the benefits of high brightness LEDs with appropriate thermal management.
Would you like more information about LEDs? Contact us online or by phone 1.877.NEMALUX.