The lighting revolution

Lighting technology has been reinvented continuously since the first light bulb was patented in the late 19th century

By Catherine Bischofberger

The invention of the light bulb had a major effect on the lives of people in the 20th century. Over the years, lighting technology has never ceased to evolve. The various milestones reached along the way coincide with some important dates in the history of the IEC.

from incandescent to LED The evolution of lighting: incandescent, CFL and LED light bulbs (Photo: Petr Kratochvil)

The early days

One of the first incandescent electric light bulbs was patented by Thomas Edison in 1878. Edison profited from the work of scientists who had produced different forms of light bulbs and filed a number of patents before him. Most of these inventions were not ready for commercialization, however, as the bulbs drew a large supply of electric current. Edison was one of the first to realize that a more energy efficient light bulb was required. His patent was for an electric lamp using a carbon filament or strip coiled and connected to platina contact wires.

In 1904, tungsten filament lamps were first marketed by a Hungarian company. The luminous efficiency, the quality and the durability of tungsten filament light bulbs was much higher than for the carbon filament incandescent light bulbs which were the norm at the time. The company’s records state that “the volume of production reached 25-30 000 pieces a day in the fiscal year 1905/1906”.

New IEC technical committees

IEC Technical Committee (TC) 6: Lamp sockets and caps, was founded in 1919 and preceded the production of the first coil bulbs in the 1920s. Subsequent coiled-coil designs greatly reduced the length of the filament in the light bulb, producing brighter light, more efficiently than straight and single coil lamps. The TC was later disbanded and its work taken over by IEC TC 23: Electrical accessories, created in 1934.

IEC TC 34: Lamps and related equipment, was the first TC to be set up after the Second World War. “Engineers from different countries in the lamp industry had always communicated with each other. That spirit of cooperation survived the war. It was clear to most of them that after having lived through such terrible events, they needed to make their collaboration more official. This led to the creation of IEC TC 34 in 1948”, explains Horst Porembski, who chaired the Technical Committee from 2003 to 2005.

Modern times

The first fluorescent lamp was invented in the 1890s but modern compact fluorescent lamps (CFLs) were commercialized since the 1980s. They were developed in response to the energy crisis of the 1970s. A Dutch company introduced the first successful screw-in CFL replacement for an incandescent lamp in 1980. CFLs use between one-fifth and one-third of the electric power of incandescent bulbs and last eight to 15 times longer. However CFLs are difficult to dispose of as they contain mercury. An electric current is driven through a tube containing argon and a small amount of mercury vapour. This generates invisible ultraviolet light that excites a fluorescent coating (phosphor) on the inside of the tube, which then emits visible light. Throughout the 1990s, IEC TC 34 published several Standards relating to CFLs; they have been updated regularly since then.

LEDs enter the fray

The first recorded appearance of an LED light can be traced back to 1962. In those days, light emitting diodes were expensive to make and could only emit a small output of infrared light. Scientists worked on increasing the efficiency of LEDs throughout the 1990s. When LED light bulbs first hit the market in the early 2000s, they lasted much longer than incandescent bulbs but were more expensive. As production volumes rose, prices gradually came down. IEC TC 34 has published several Standards relevant to LEDs from the 2000s onwards, including IEC 62031, which specifies the safety requirements for LEDs and was issued in February 2018.

In 2015, the IEC Quality Assessment System for Electronic Components (IECQ), created the IECQ Scheme for LED Lighting. IECQ can be applied as a means of certifying manufacturers and suppliers of the electronic components, modules and assemblies used in the production of LED packages, engines, lamps, luminaires and associated LED ballasts/drivers. It provides a standardized approach for evaluating suppliers and acts as a powerful supply chain management tool when assessing and monitoring the various tier-level suppliers. It gives consumers the assurance that suppliers who are covered by the Scheme, manufacture products which meet the appropriate standards in terms of reliability, safety and cost-efficiency.

The current Chair of IEC TC 34, Andreas Scholtz, is keen to stress the fundamental change brought about by the introduction of LED lighting. “LED is a revolution just as important as the invention of the first light bulb. It has a huge impact on the way TC 34 works as well. In the past, a limited number of players prepared Standards for lamps, luminaires, caps and holders as well as control gear. But with the advent of LED lighting and all its inherent possibilities, a new way of managing the TC is required. Light technology is now linked to the Internet of Things, to building automation, to IT applications and to artificial intelligence. This accelerated technology convergence, coupled with an increased number of stakeholders from different industries, changes the way we should be viewed. The TC must be seen as a centre of competence for the standardization of lighting products. This means we need to intensify existing liaisons and establish new partnerships”, he says.

Smart lights for smart cities and homes

Smart public lighting management systems are already used in several cities around the world. As the proportion of the world’s population living in urban dwellings is expected to grow to 66% by 2050, according to the UN, these systems will make increasing sense, as they enable considerable savings in energy to be made. Smart lights can switch themselves on when people are in the streets and off when these are deserted. They perform a rising number of tasks, such as guiding car drivers to the closest parking space. They are also increasingly used in the home. They can be voice-controlled from a distance and employed to convey information.

Li-Fi is a visible light communications system that uses LED light. It is capable of transmitting data at high speeds over the visible light spectrum as well as in the ultraviolet and infrared waveband. It is similar to Wi-Fi, but uses light to transmit data instead of radio frequencies. The technology has many advantages over Wi-Fi, including the lack of electromagnetic interference. It is also 100 times faster.

OLEDs and lasers

OLEDs use an organic compound as a semiconductor which emits light in response to an electric current. OLED displays can be manufactured on flexible plastic substrates. They are already used for car lights, mobile phone displays and even television screens. Inside Subcommittee (SC) 34A, Working Group 3 has been set up to prepare and maintain Standards for OLED light sources.

Scientists who are looking at laser lighting believe it could be the next big breakthrough. Steven DenBaars, the director of the solid state lighting and energy electronics centre at the University of California, Santa Barbara, has been leading research into how to route laser lighting through fibre optic cables. According to Andreas Scholtz, IEC TC 34 has work in the pipeline related to laser technology. “Standards are necessary because there has been some concern about the safety of laser lighting and how it could affect people’s eyesight. We need to ensure that future products are safe and convince the public they are safe, as well.”

light rveolutionized the lives of people in the 20th century Lights revolutionized the lives of people in the 20th century (Photo: Pixabay)
lighting technology kept on evolving An early tungsten filament light bulb (Photo: A-D Page, Journal of the AIEE)
from incandescent to LED The evolution of lighting: incandescent, CFL and LED light bulbs (Photo: Petr Kratochvil)
CFL and incandescent bulbs in hands1 CFLs save energy compared to ordinary incandescent light bulbs (Photo: Greg Allen)