Glossary - Light, Home & Building

Electronic control

What is LED DRIVER?

A device that controls the current flow and manages power for an LED lighting product. In some LED applications we understand under term LED Driver also part of the power supply like voltage conversion circuit used between input voltage and required output voltage. According to the type of output we have three groups of drivers: Constant Current (CC) – LEDs are in serial connection and driver delivers precise current value, Constant Voltage (CV)- LEDs are in parallel connection which is ideal for decorative LED strips, this topology is not recommended for dimming and Special Drivers (CC+CV) – which is a bit expensive solution allowing both serial and parallel connections. Beside mentioned there are following important parameters we shall pay attention when choosing LED Driver like Rated Current/Voltage – predefined output current and voltage, Rated Power – output power of the driver and Efficacy – Ratio between output/input power.

Lighting matters

Light sources for my lighting solution

Over the years many light sources have been developed and used in many and sometimes very special applications.
These include:

• Fluorescent TL lamps; generally known as office ‘neon’ lamps.
• CFL (compact fluorescent lamps); the ‘classic’ replacement for incandescent bulbs as they fit into the old sockets.
• CCFL (cold cathode fluorescent lamps); mainly used for outdoor ‘neon’ signs and LCD display backlights.
• HID light (high intensity discharge); typically used for street and stadium lighting as well as for car headlights.
• LEDs; this very effective lighting technology is mature and provides the lamp designer with new possibilities in terms of the physical and optical construction of the entire lamp. As the operating lifetime of LEDs is between 20,000 and 50,000 hours, which is considerably longer than most lamp operating lifetimes, LEDs are and will be the light source of the future for general lighting applications.
   

Optics

Why OPTICs are needed?

Once the light is emitted from the light source it needs to be directed and guided according to the individual application needs. This can be performed by reflection (from metallised or white diffuse surfaces), refraction through prisms or lenses or even absorption by black or structured surfaces. Compared to conventional lamp systems, the optical system of LED lights is about 30% more effective due to lower losses. Therefore it is important to consider the entire optical system within the evaluation process for the efficacy of a lighting system.