Language: My WERMA My shopping cart:0 item(s) Home Products Solutions Service & Support Company Tech-Talk Light in Signalling technology Light in Signalling technology Optical Signals in everyday life The field of signalling technology offers us not only the possibility of audible signals, but also that of optical signals. These are to be found everywhere in everyday life; at traffic lights, in alarm systems or where obstructions arise. Countless uses can also be found in the industrial sector, above all in the signalisation of a machine operating status. The generation of light – a summary of the possibilities Light can be generated in various ways. Signalling technology mostly uses bulbs, halogen bulbs, electric discharge tubes and LEDs. Bulbs A tungsten filament is heated up to a high temperature, so radiating energy over a wide wavelength. This is perceived as light similar to sunlight. The tungsten filament evaporates with time. When the tungsten content falls below a certain level, the maximum life duration of the bulb is reached. As tungsten oxidises quickly and is destroyed when it comes into contact with air, the filament must be kept in a non-oxidising atmosphere such as vacuum. This leads us to the familiar light bulb with its sealed glass body. Halogen bulbs These are bulbs wherein the tungsten filament is enclosed by a small amount of halogen. The resulting chemical reaction has the effect of lengthening the life of the tungsten and stabilising the light output throughout the entire life duration of the bulb. Electric discharge tubes Xenon flash tubes are widely used in signalling technology. They consist of a glass tube filled with the inert gas xenon. A sufficiently high voltage leads to a discharge of energy with a spark gap and a flash of high intensity. LED Light emitting diodes are constructed using certain semiconductors. Foreign atoms are built into the semiconductor with the purpose of optimising the conductibility. Half of the semiconductor (n-region) is doped with foreign atoms that contain one bonding electron more than the semiconductor atom. This surplus atom can move freely and increases conductibility. The other half (p-region) is doped with foreign atoms containing one electron less than the semiconductor. When the LED is switched on, these faults ("holes") fill up with free electrons (recombination). Energy in the form of radiant photons is hereby released. The energy and therefore the colour of the light emitted is determined by the material the semiconductor is made of; e.g. GaAsP (Gallium Arsenic Phosphide) results in red light. LED – Beacons with many advantages LEDs offer many advantages when compared with conventional light bulbs: Minute dimensions Low current consumption Low heat generation Extremely high life duration up to 50,000 hours All major colours can be realised Vibration and shock resistance Immediate illumination Fundamental units of light magnitude The fields of lighting and signalling technology differentiate between fundamental units to define light itself. The most important of these are the units Lumen, Candela and Lux. Lumen (unit lm) Light current is measured in Lumen; this is the unit for the entire visible light output of a light-emitting source. The light current is defined by the following formula known as the brightness characteristic: Light current Φ [in lm] = radiation capacity x brightness characteristic V(λ) The brightness impression upon the human eye is based on a sensitivity curve V(λ) which reproduces the sensation felt by the eye in relation to the wavelength. The maximum point on this curve is at about 555 nm; we see best at this wavelength; V(555 nm) = 1. Candela (unit cd) In signalling technology only the part of the light current that is emitted in a certain direction is of importance. This light intensity is measured in Candela. It is defined by the light current of a lamp and the steradian measure . Light intensity [in cd] = Light current Φ / Steradian measure Ω A complete sphere has a dihedral angle of Ω = 4 π sr. sr stands for the steradian and is the unit for the dihedral angle. Example: a household candle emitting a light intensity of 12,566 Lumen has a light inten sity in relation to the steridian measure ≈ 1cd. This explains the name: candela is the Latin word for candle. Lux (unit lx) Illumination density is an important unit in lighting installations. It is the measure of the brightness with which an area is illuminated. Whereas light intensity (in cd) is a property of a light source, illumination density is calculated in regard to the area to be illuminated. Where the light current emitted is constant, the following formula is applicable: Light density E [in lux] = Light current Φ / Surface A Types of optical signal devices Video: WERMA UK - Lichtvergleich einbauen We differentiate between permanent, blinking and flashing beacons as well as beacons with rotating light. The appropriate signal type must be chosen to meet the needs of the specific application, whether as a warning, an informative signal or a simple piece of information. Signalling technology relies mainly on the colours green, red, yellow, blue and clear. The following diagram shows the position of these colours in the spectrum: WERMA offers all round capabilities in optical and audible signals for the most arduous conditions WERMA places very high demands on itself with regard to product quality and life duration. High investment in our laboratory and development areas underpin this activity. WERMA has risen to a new technologicel level through the work with its Light Laboratory and Thermo Analysis equipment, both of which have led to improved flexibility and know-how within the development department. This in turn leads to a quicker response to customer demands - all of course within the confines of the high WERMA quality. The sophisticated Thermoanalysis equipment and our in-house Light Laboratory is leading to much more objective evaluation of the life duration of our products. This means it is possible to offer an optimised product with the longest possible life duration, brightest or most appropriate light picture and best thermodynamics. WERMA has an unprecedented know how and quality in the field of LED technology. Performance Measurement: Light distribution charts (Polardiagram) in Candela. Light intensity measurement. Timed lapse measurement of light in Candela and Lux. Flash intensity measurement in Candela. Key to optical signals Colour: Red Meaning: extreme danger/hazardous conditions Colour: Yellow Meaning: beware/dangerous conditions imminent Colour: Green Meaning: normal conditions Colour: Blue Meaning: conditions requiring defined action Colour: White/Clear Meaning: no particular meaning Experience and Know-How – the right combination WERMA can look back on many years of experience and in-depth knowledge in the field of optical signals. Our technicians have been researching the fundamental principles of light effusion for many years, and the fruits of their work flow into the conception and development of all new products. Our guiding principle has always been to implement and realise the newest trends in technology. To achieve this goal we employ a large and competent team of R + D engineers and invest in the most modern testing facilities. It is WERMA’s declared goal to market only truly innovative products; with this in mind, we invest about 11% of overall expenditure in the development of new products, a strategy which will enable WERMA to carry on setting the standards in the field of optical signalling. Research and development as the basis for innovation The different types of optical signal devices call for an individually suited transparent housing, known as a lens. The lens of a flashing beacon has, for example, an especially designed ribbing. The light is dispersed in such a way as if the whole lens is flashing. The lens of a rotating mirror beacon is by contrast a consistent thickness. The rotating light signal is not scattered here, but bundled to a point. The precise setting of the rotating mirror is of great importance, as the aim is to attain the greatest possible bundling of light. WERMA is able to make exact calculations regarding the positioning of the path of rays. The optical laboratory can measure all relevant units of light. Even the brightness curve of a flash can be analysed in nanoseconds. Reliable LED technology WERMA is a market leader in the use of LED technology parallel to conventional bulbs and halogen bulbs. The advantages are obvious: high life duration, low heat emission, and low current consumption. Even flashing light can be produced using LEDs. WERMA uses different types of LEDs in its optical signal devices: Chip-on-Board (COB), SMD, and wired LEDs (e.g. Super-Flux). With the COB method, single LED chips are bonded onto a gold-plated printed circuit board. With SMD LEDs he chip itself is already encased in a housing and is set onto the printed circuit board with the other components on WERMA’s own assembly line. Super-Flux models are characterised by their extreme light intensity and are used whenever a signal must be particularly bright. Newsletter We would like to keep you up to date with all future WERMA developments. 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