Types of light source
Incandescent light bulb
An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to a high temperature, by passing an electric current through it, until it glows with visible light (incandescence). The hot filament is protected from oxidation with a glass or quartz bulb that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposit metal vapor onto the filament, extending its life. The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.
Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent lamp is widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.
Compact Fluorescent lamp (CFL)
A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent lamp; some types fit into light fixtures formerly used for incandescent lamps. The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp.
Compared to general-service incandescent lamps giving the same amount of visible light, CFLs use one-fifth to one-third the electric power, and last eight to fifteen times longer. A CFL has a higher purchase price than an incandescent lamp, but can save over five times its purchase price in electricity costs over the lamp’s lifetime. Like all fluorescent lamps, CFLs contain toxic mercury which complicates their disposal. In many countries, governments have banned the disposal of CFLs together with regular garbage. These countries have established special collection systems for CFLs and other hazardous waste.
The principle of operation in a CFL bulb remains the same as in other fluorescent lighting: electrons that are bound to mercury atoms are excited to states where they will radiate ultraviolet light as they return to a lower energy level; this emitted ultraviolet light is converted into visible light as it strikes the fluorescent coating on the bulb (as well as into heat when absorbed by other materials such as glass).
CFLs radiate a spectral power distribution that is different from that of incandescent lamps. Improved phosphor formulations have improved the perceived colour of the light emitted by CFLs, such that some sources rate the best “soft white” CFLs as subjectively similar in colour to standard incandescent lamps.
A halogen lamp, also known as a tungsten halogen, quartz-halogen or quartz iodine lamp, is an incandescent lamp that has a small amount of a halogen such as iodine or bromine added. The combination of the halogen gas and the tungsten filament produces a halogen cycle chemical reaction which redeposit evaporated tungsten back onto the filament, increasing its life and maintaining the clarity of the envelope. Because of this, a halogen lamp can be operated at a higher temperature than a standard gas-filled lamp of similar power and operating life, producing light of a higher luminous efficacy and colour temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination.
An LED lamp is a light–emitting diode (LED) product which is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency which are several times longer than incandescent lamps, and significantly more efficient than most fluorescent lamps, with some chips able to emit more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers). The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%.
Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and compact fluorescent lamps or CFLs), LEDs come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off. The initial cost of LED is usually higher. Degradation of LED dye and packaging materials reduces light output to some extent over time.
What is a lumen?
A lumen is a measurement of light. In more technical terms, a lumen is a finite measurement of how much visible light is emitted by a source and which can be detected by the human eye. Lumens are increasingly being used on the packaging of bulbs in an attempt to help consumers make more informed choices.
As explanation of Wikipedia:
If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux emitted into that angle is one lumen (1 cd·1 sr = 1 lm). Alternatively, an isotropic one-candela light-source emits a total luminous flux of exactly 4π lumens. If the source were partially covered by an ideal absorbing hemisphere, that system would radiate half as much luminous flux—only 2π lumens. The luminous intensity would still be one candela in those directions that are not obscured.
The lumen can be thought of casually as a measure of the total “amount” of visible light in some defined beam or angle, or emitted from some source. The number of candelas or lumens from a source also depends on its spectrum, via the nominal response of the human eye as represented in the luminosity function.
The difference between the units lumen and lux is that the lux takes into account the area over which the luminous flux is spread. A flux of 1000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux. Mathematically, 1 lx = 1 lm/m2.
A source radiating a power of one watt of light in the colour for which the eye is most efficient (a wavelength of 555 nm, in the green region of the optical spectrum) has luminous flux of 683 lumens. So a lumen represents at least 1/683 watts of visible light power, depending on the spectral distribution.
Table below shows compare of 3 type of light source
|450||4 – 5||8 – 12||40|
|750 – 900||6 – 8||13 – 18||60|
|1100 – 1300||9 – 13||18 – 22||75 – 100|
|1600 – 1800||16 – 20||23 – 30||100|
|2600 – 2800||25 – 28||30 – 55||150|
Colour psychology is the study of hues as a determinant of human behavior. Colour influences perceptions that are not obvious, such as the taste of food. Colours can also enhance the effectiveness of placebos. For example, red or orange pills are generally used as stimulants. Another way in which Colours have been used to influence behavior was in 2000, when the company Glasgow installed blue street lights in certain neighborhoods in order to reduce the crime rate. Colour can indeed influence a person; however, it is important to remember that these effects differ between people. Factors such as gender, age, and culture can influence how an individual perceives colour. For example, males reported that red coloured outfits made women seem more attractive, while women answered that the colour of a male’s outfit did not affect his attractiveness.
Colour psychology is also widely used in marketing and branding. Many marketers see colour as an important part of marketing because colour can be used to influence consumers’ emotions and perceptions of goods and services. Companies also use colour when deciding on brand logos. These logos seem to attract more customers when the colour of the brand logo matches the personality of the goods or services, such as the colour pink being heavily used on Victoria’s secret branding. However, colours are not only important for logos and products, but also for window displays in stores. Research shows that warm colours tended to attract spontaneous purchasers, despite cooler colours being more favorable
Everyone thinks that response to colour, being subjective, must therefore be unpredictable
Specific color meaning
Positive: Physical courage, strength, warmth, energy, basic survival, ‘fight or flight’, stimulation, masculinity, excitement.
Negative: Defiance, aggression, visual impact, strain.
Being the longest wavelength, red is a powerful colour. Although not technically the most visible, it has the property of appearing to be nearer than it is and therefore it grabs our attention first. Hence its effectiveness in traffic lights the world over. Its effect is physical; it stimulates us and raises the pulse rate, giving the impression that time is passing faster than it is. It relates to the masculine principle and can activate the “fight or flight” instinct. Red is strong, and very basic. Pure red is the simplest colour, with no subtlety. It is stimulating and lively, very friendly. At the same time, it can be perceived as demanding and aggressive.
Positive: Intelligence, communication, trust, efficiency, serenity, duty, logic, coolness, reflection, calm.
Negative: Coldness, aloofness, lack of emotion, unfriendliness.
Blue is the colour of the mind and is essentially soothing; it affects us mentally, rather than the physical reaction we have to red. Strong blues will stimulate clear thought and lighter, soft blues will calm the mind and aid concentration. Consequently it is serene and mentally calming. It is the colour of clear communication. Blue objects do not appear to be as close to us as red ones. Time and again in research, blue is the world’s favourite colour. However, it can be perceived as cold, unemotional and unfriendly.
Positive: Optimism, confidence, self-esteem, extraversion, emotional strength, friendliness, creativity.
Negative: Irrationality, fear, emotional fragility, depression, anxiety, suicide.
The yellow wavelength is relatively long and essentially stimulating. In this case the stimulus is emotional, therefore yellow is the strongest colour, psychologically. The right yellow will lift our spirits and our self-esteem; it is the colour of confidence and optimism. Too much of it, or the wrong tone in relation to the other tones in a colour scheme, can cause self-esteem to plummet, giving rise to fear and anxiety. Our “yellow streak” can surface.
Positive: Harmony, balance, refreshment, universal love, rest, restoration, reassurance, environmental awareness, equilibrium, peace.
Negative: Boredom, stagnation, blandness, enervation.
Green strikes the eye in such a way as to require no adjustment whatever and is, therefore, restful. Being in the centre of the spectrum, it is the colour of balance – a more important concept than many people realise. When the world about us contains plenty of green, this indicates the presence of water, and little danger of famine, so we are reassured by green, on a primitive level. Negatively, it can indicate stagnation and, incorrectly used, will be perceived as being too bland.
Positive: Spiritual awareness, containment, vision, luxury, authenticity, truth, quality.
Negative: Introversion, decadence, suppression, inferiority.
The shortest wavelength is violet, often described as purple. It takes awareness to a higher level of thought, even into the realms of spiritual values. It is highly introvertive and encourages deep contemplation, or meditation. It has associations with royalty and usually communicates the finest possible quality. Being the last visible wavelength before the ultra-violet ray, it has associations with time and space and the cosmos. Excessive use of purple can bring about too much introspection and the wrong tone of it communicates something cheap and nasty, faster than any other colour.
Positive: Physical comfort, food, warmth, security, sensuality, passion, abundance, fun.
Negative: Deprivation, frustration, frivolity, immaturity.
Since it is a combination of red and yellow, orange is stimulating and reaction to it is a combination of the physical and the emotional. It focuses our minds on issues of physical comfort – food, warmth, shelter etc. – and sensuality. It is a ‘fun’ colour. Negatively, it might focus on the exact opposite – deprivation. This is particularly likely when warm orange is used with black. Equally, too much orange suggests frivolity and a lack of serious intellectual values.
Positive: Physical tranquillity, nurture, warmth, femininity, love, sexuality, survival of the species.
Negative: Inhibition, emotional claustrophobia, emasculation, physical weakness.
Being a tint of red, pink also affects us physically, but it soothes, rather than stimulates. (Interestingly, red is the only colour that has an entirely separate name for its tints. Tints of blue, green, yellow, etc. are simply called light blue, light greenetc.) Pink is a powerful colour, psychologically. It represents the feminine principle, and survival of the species; it is nurturing and physically soothing. Too much pink is physically draining and can be somewhat emasculating.
Positive: Psychological neutrality.
Negative: Lack of confidence, dampness, depression, hibernation, lack of energy.
Pure grey is the only colour that has no direct psychological properties. It is, however, quite suppressive. A virtual absence of colour is depressing and when the world turns grey we are instinctively conditioned to draw in and prepare for hibernation. Unless the precise tone is right, grey has a dampening effect on other colours used with it. Heavy use of grey usually indicates a lack of confidence and fear of exposure.
Positive: Sophistication, glamour, security, emotional safety, efficiency, substance.
Negative: Oppression, coldness, menace, heaviness.
Black is all colours, totally absorbed. The psychological implications of that are considerable. It creates protective barriers, as it absorbs all the energy coming towards you, and it enshrouds the personality. Black is essentially an absence of light, since no wavelengths are reflected and it can, therefore be menacing; many people are afraid of the dark. Positively, it communicates absolute clarity, with no fine nuances. It communicates sophistication and uncompromising excellence and it works particularly well with white. Black creates a perception of weight and seriousness.
Positive: Hygiene, sterility, clarity, purity, cleanness, simplicity, sophistication, efficiency.
Negative: Sterility, coldness, barriers, unfriendliness, elitism.
Just as black is total absorption, so white is total reflection. In effect, it reflects the full force of the spectrum into our eyes. Thus it also creates barriers, but differently from black, and it is often a strain to look at. It communicates, “Touch me not!” White is purity and, like black, uncompromising; it is clean, hygienic, and sterile. The concept of sterility can also be negative. Visually, white gives a heightened perception of space. The negative effect of white on warm colours is to make them look and feel garish.
Positive: Seriousness, warmth, Nature, earthiness, reliability, support.
Negative: Lack of humour, heaviness, lack of sophistication.
Brown usually consists of red and yellow, with a large percentage of black. Consequently, it has much of the same seriousness as black, but is warmer and softer. It has elements of the red and yellow properties. Brown has associations with the earth and the natural world. It is a solid, reliable colour and most people find it quietly supportive – more positively than the ever-popular black, which is suppressive, rather than supportive.
Top 10 Benefits of LED Lighting
1. Long Life
Long life time stands out as the number one benefit of LED lights. LED bulbs and diodes have an outstanding operational life time expectation of up to 100.000 hours. This is 11 years of continuous operation, or 22 years of 50% operation. If you leave on the LED fixture for 8h per day it would take around 20 years before you’d have to replace the LED bulb.
LED’s are different to standard lighting: They don’t really burn out and stop working like a standard light, moreover the lighting diodes emit lower output levels over a very long period of time and become less bright.
2. Energy Efficiency
Today’s most efficient way of illumination and lighting, with an estimated energy efficiency of 80%-90% when compared to traditional lighting and conventional light bulbs. This means that about 80% of the electrical energy is converted to light, while a ca. 20% is lost and converted into other forms of energy such as heat.
With traditional incandescent light bulbs who operate at 20% energy efficiency only, an 80% of the electricity is lost as heat. Imagine the following scenario:
If you use traditional lighting and have an electricity bill of e.g. US$ 100, then US$ 80 of that money has been used to heat the room, not to light it! Using LED illumination with 80% efficiency, the electricity costs would be around US$ 20 and you’d have saved around US$ 80.
The long operational life time acts as a multiplication and helps achieve even more energy efficiency, especially large scale and when thinking in terms of urban infrastructure projects, such as cities, railroads and airports.
Think of e.g. an airport using energy efficient LED lighting exclusively and achieving a 30% power consumption reduction in comparison with an airport using conventional lighting technology.
Because the long life span of LED lights, also the maintenance work – think of all the work and energy it would take to purchase, stock and change the conventional light bulbs of an airport – you’ll see that you can make significant energy savings also when it comes to maintenance and replacement due to the long operational life times of LED lighting.
3. Ecologically Friendly
LED lights are free of toxic chemicals. Most conventional fluorescent lighting bulbs contain a multitude of materials like e.g. mercury that are dangerous for the environment.
LED lights contain no toxic materials and are 100% recyclable, and will help you to reduce your carbon footprint by up to a third. The long operational life time span mentioned above means also that one LED light bulb can save material and production of 25 incandescent light bulbs. A big step towards a greener future!
4. Durable Quality
LEDs are extremely durable and built with sturdy components that are highly rugged and can withstand even the roughest conditions.
Because LED lights are resistant to shock, vibrations and external impacts, they make great outdoor lighting systems for rough conditions and exposure to weather, wind, rain or even external vandalism, traffic related public exposure and construction or manufacturing sites.
5. Zero UV Emissions
LED illumination produces little infrared light and close to no UV emissions.
Because of this, LED lighting is highly suitable not only for goods and materials that are sensitive to heat due to the benefit of little radiated heat emission, but also for illumination of UV sensitive objects or materials such a in museums, art galleries, archeological sites etc.
6. Design Flexibility
LEDs can be combined in any shape to produce highly efficient illumination. Individual LEDs can be dimmed, resulting in a dynamic control of light, colour and distribution. Well-designed LED illumination systems can achieve fantastic lighting effects, not only for the eye but also for the mood and the mind:
LED mood illumination is already being used in airplanes, classrooms and many more locations and we can expect to see a lot more LED mood illumination in our daily lives within the next few years.
7. Operational in Extremely Cold or Hot Temperatures
LED are ideal for operation under cold and low outdoor temperature settings. For fluorescent lamps, low temperatures may affect operation and present a challenge, but LED illumination operates well also in cold settings, such as for outdoor winter settings, freezer rooms etc.
8. Light disbursement
LED is designed to focus its light and can be directed to a specific location without the use of an external reflector, achieving a higher application efficiency than conventional lighting. Well-designed LED illumination systems are able to deliver light more efficiently to the desired location.
9. Instant Lighting & Frequent Switching
LED lights brighten up immediately and when powered on, which has great advantages for infrastructure projects such as e.g. traffic and signal lights.
Also, LED lights can switched off and on frequently and without affecting the LED’s lifetime or light emission. In contrast, traditional lighting may take several seconds to reach full brightness, and frequent on/off switching does drastically reduce operational life expectancy.
A low-voltage power supply is sufficient for LED illumination. This makes it easy to use LED lighting also in outdoor settings, by connecting an external solar-energy source and is a big advantage when it comes to using LED technology in remote or rural areas