Spectrum of the glow of the sun. Color temperature of light. Warm, neutral and cold white light

In this article, we will show by simple examples what the technical characteristics of the color temperature or "color" mean in the description of LED lamps.

The color temperature in the description of lamps is measured in degrees on the Kelvin scale (K) and characterizes the shade of their light when perceived by a person's vision. To simplify the understanding of buyers, manufacturers mark their products not only by indicating the color temperature of the LED lamp, but also by the visual matching of their hue in the figures. Warm light is white light with a yellowish tinge and the lower the degree on the Kelvin scale, the more yellow the shade and the "warmer" the light emitted by them. Conversely, the higher the indicated temperature, the darker the shade. The most accessible to evaluate these characteristics can be in the figure below:

For even more simplification, we can draw some analogies on the color shade of light between the color temperature and the usual shades of lighting:

• 800 K  - the initial boundary of the red-hot incandescence visible to the eye;
• 1500-2000 K  - light from the fire of a conventional wax candle;
• 2700 K  - Traditional incandescent lamp 40-75 W;
• 3000 K  - a very powerful traditional light bulb with a filament (more than 150 W), halogen bulb;
• 3400 K- the light of the sun on the horizon;
• 4200 K- a standard fluorescent lamp, the so-called "tube" form - they are often used in entrances, offices, corridors (visually, it is still relatively warm white light);
• 4300-4500 K- The light of the sun in the morning and at 14-15 hours;
• 4500-5000 K  - the light of most automobile xenon lamps;
• 5000 K  - sunlight at noon time (about 12 hours);
• 5500-5600 K  - camera flash;
• 6500-7500 K  - light in cloudy weather;
• 7500-8500 K  - light in the evening during sunset;
• 9500 K  - the light of the blue clear sky at sunrise;
• 15000 K  - a deep blue light, characteristic of a clear winter sky.

The first household LED lamps were distinguished by a bright white light with a noticeable bluish tint. The color temperature of such lamps was at the level of 5500-6500 K. This shade of light is normally perceived by a person on the street and very similar to bright daylight, but in rooms such light was not very comfortable for a person. For example, the light from the usual incandescent lamps is in the range from 2500 to 3000 degrees Kelvin and has a clear yellowish tint, which is very comfortable for the eyes. It is for this reason that the manufacturing technologies for LED lamps have been improved to transfer their emission spectrum to lower temperatures and most LED lamps for household purposes today have similar color characteristics with conventional incandescent lamps.

LED lamps began active penetration not only in the household, but also in the office, public (shops, theaters, galleries) and industrial light, where the shade of light is needed differently. Therefore, the choice of the shade of lighting when buying lamps is already very worthy and it is possible to select an LED lamp and lamp for any purpose.

Articles on LED lighting

This article is for those who for the first time asked such a question and have no technical education. LED lighting is the lighting of something using relatively new light sources - LEDs. LED is an industrially created crystal that, when connected to electricity, begins to emit light. Fairly speaking, a new light source can not be called a light-emitting diode; it was invented already several decades ago, but it was actively developed and used in all spheres of our life only in the beginning of 2000, thanks to new discoveries in the technological field and a significant reduction in the cost of production.

Modern technologies do not stand still, and scientific and technological progress does not leave out such a sphere of our life as coverage. Development occurs both in the direction of increasing lighting technical characteristics, and in the direction of the appearance of additional adjacent technological devices that increase the utility of fixtures and lighting systems in general. We are talking about numerous varieties of LED lamps with built-in sensors.

We decided to make a survey, which will collect the most interesting feedback about LED lamps. We collected these reviews both from our customers (and continue to collect), and from the Internet - from various forums, blogs, thematic portals and other resources. Having received a large amount of data, we systematized it, de-identified it and got a set of interesting opinions and advice from real people using LED lamps at home, in the country, in the office, etc.

Customers of our online store often ask questions - which LED lamps are the best, which companies? What exactly are they better? Is it possible to trust the characteristics of the lamps indicated on the package? Can I buy LED lamps made in China? Can I use LED lamps in children's rooms? This is only part of the questions that customers ask when choosing the best option for themselves. And such questions arise when the buyer already knows which type of lamps is needed and with what characteristics. In this article we will try to answer all these questions and avoid new puzzles for the consumer :-)

LED is a semiconductor device that transforms electric current into light. LED has a common abbreviation - LED (light-emitting diode), which in literal translation into Russian means "light-emitting diode". The LED consists of a semiconductor chip (chip) on a substrate, a housing with contact terminals and an optical system. Directly the radiation of light comes from this crystal, and the color of the visible radiation depends on its material and various additives. As a rule, there is one crystal in the LED casing, but if you need to increase the power of the LED or for radiation of different colors, several crystals can be installed.

This is certainly the most important issue, since the world today is on the threshold of a new era in lighting technologies and one must be sure that LED lighting does not cause harm to health. To date (2014), this issue can not be considered thoroughly studied, since the period of introduction of LED lighting into a person's life is still quite small and the necessary amount of statistical data for analysis has not yet been accumulated. Nevertheless, at the moment there is a huge amount of facts and opinions of professionals in this field, indicating that there is no harm from LED lighting.

This article is for those who do not understand bulbs, types of their socles and electricity in general, but already understands that it is economically much more profitable to use LED lamps than incandescent lamps and even than fluorescent ones (they are often called "energy-saving" lamps). To find the right LED lamps is very simple and we will help you make the right choice, following the instructions below. Or you can call us right away and we will gladly help with the choice.

Introduction .................................................................................... 1. The concept of color temperature ................................................ ... .. 1.1. Table of numerical values ​​of the color temperature of the widely used light sources ........................................................................ .. 1.2. Color Chart XYZ ..........................................................

1.3.Solight light and the Color rendering index (CRI).

2. Methods of measuring the color temperature ........................................... Sources of information ...................................................................

Introduction.

According to our psychological sensations, colors are warm and hot, they are cold and very cold. In fact, all colors are hot, very hot, because each color has its own temperature and it is very high. Any object in the world around us has a temperature above absolute zero, which means it emits heat radiation. Even ice, in which a negative temperature, is the source of thermal radiation. It's hard to believe, but it's true. In nature, a temperature of -89 ° C is not the lowest, it is possible to achieve even lower temperatures, although, for the time being, in the laboratory. The lowest temperature, which at the moment is theoretically possible within our universe, is the absolute zero temperature and it is -273.15 ° C. At this temperature, the movement of molecules of matter ceases and the body completely ceases to emit any radiation (thermal, ultraviolet, and even more so visible). Total darkness, there is no life, no heat. Perhaps one of you knows that the color temperature is measured in the Kelvin. Who bought home energy-saving light bulbs, he saw the inscription on the package: 2700K or 3500K or 4500K. This is just the color temperature of the light emitted by the light bulb. But why is measured in the Kelvin, and what does Calvin mean? This unit of measure was proposed in 1848. Ulyam Thomson (aka Lord Kelvin) and officially approved in the International System of Units. In physics and sciences, which are directly related to physics, the thermodynamic temperature is measured just by the Kelvinas. The start of the temperature scale report begins at the 0 Kelvin point, which means - 273.15 degrees Celsius. That is, 0K is the absolute zero of temperature. It is easy to translate the temperature from Celsius to Kelvin. To do this, simply add the number 273. For example, 0 ° C is 273K, then 1 ° C is 274 K, by analogy, the human body temperature is 36.6 ° C, it is 36.6 + 273.15 = 309.75K. That's how it all works out.

Chapter 1. The concept of color temperature.

Let's try to figure out what color temperature is.

The sources of light are hot bodies heated to high temperatures, whose thermal vibrations of atoms cause radiation in the form of electromagnetic waves of different lengths. Radiation, depending on the wavelength, has its own color. At low temperatures and correspondingly for longer wavelengths, radiation with a warm, reddish chromaticity of the light flux predominates, and at higher wavelengths, with a decrease in wavelength, with a cold, blue-blue chromaticity. The unit of wavelength is a nanometer (nm), 1nm = 1/1 000 000mm. As early as the 17th century, Isaac Newton, with the help of a prism, laid out the so-called white daylight and received a spectrum of seven colors: red, orange, yellow, green, blue, blue, violet, and as a result of various experiments proved that any spectral color can be To obtain a mixture of light fluxes, consisting of different ratios of three colors - red, green and blue, which were called the main ones. So the theory of three-component appeared.

The human eye perceives the chromaticity of light through receptors, the so-called cones, which have three varieties, each of which perceives one of the three primary colors - red, green or blue and has its own sensitivity to each of them. The human eye perceives electromagnetic waves in the range from 780 to 380 nanometers. This is the visible part of the spectrum. Consequently, and the light detectors of information carriers - film and photographic film or camera matrix - should have an identical sensitivity to color. Sensitized films and matrixes of video cameras perceive electromagnetic waves in a slightly wider range, capturing the near infrared (IR) radiation in the range of 780-900 nm and nearby to violet-ultraviolet (UV) radiation in the range of 380-300 nanometers. This spectral region, in which the geometric optics and photosensitive materials operate, is called the optical range.

The human eye except for light and dark adaptation has a so-called color adaptation, thanks to which, with different sources, with different ratios of the wavelengths of the primary colors, correctly perceives colors. The film and matrix do not possess such properties, they are balanced to a certain color temperature.

The heated body, depending on the heating temperature in its radiation, has a different ratio of different wavelengths and correspondingly a different color of the light flux. The standard, according to which the chromaticity of the radiation is determined, is an absolutely black body (AKHT), the so-called "blackbody". emitter of the Planck. Absolutely black body - a virtual body that absorbs 100% of the incident light, is described by the laws of thermal radiation. And the color temperature is the temperature of the ACT in degrees Kelvin, in which the color of its radiation coincides with the color of the given radiation source. The difference between the temperature scale in degrees Celsius, where the freezing point of water is taken as zero, and the scale in degrees Kelvin is -273, 16, because the reference point on the Kelvin scale is taken to be the temperature at which any movement of atoms in the body ceases and any radiation ceases accordingly , the so-called absolute zero, corresponding to the temperature of Celsius-273.16 degrees. That is, 0 degrees Kelvin corresponds to a temperature of -273.16 degrees. Celsius.

The main natural source of light for us is the Sun and various sources of light - fire in the form of a fire, matches, torches and lighting fixtures, ranging from household appliances, appliances and ending with professional lighting devices designed specifically for cinematography and television. Both in household appliances and in professional, different lamps are used (we will not touch on their principle of operation and design differences) with different energy ratios in their emission spectra of primary colors, which can be expressed by the color temperature. All light sources are divided into two main groups. The first, with a color temperature (Tcv.) 5600 0K, white daylight (DS), whose radiation is dominated by the short-wave, cold part of the optical spectrum, the second - incandescent lamps (LN) with Tcv.-32000K and the predominance in radiation of long-wave, optical spectrum.

How does it all begin? Everything starts from zero, including light radiation. Black color is the absence of light at all. In terms of color, black is 0 intensity of radiation, 0 saturation, 0 color tone (it simply does not exist), this is the total absence of all colors in general. Why do we see the object black, but because it almost completely absorbs all the light falling on it. There is such a thing as an absolutely black body. Absolutely black body is called an idealized object, which absorbs all the radiation incident on it and does not reflect anything. Of course, in reality this is unattainable and absolutely black bodies do not exist in nature. Even those items that seem black to us, in fact, are not absolutely black. But you can make a model of an almost black body. The model is a cube with a hollow structure inside, a small hole is made in the cube through which light rays penetrate inside the cube. The design is something like a birdhouse. Look at the picture (1).

Picture 1). - A model of an absolutely black body.

The light entering through the hole after the multiple reflections will be completely absorbed, and the hole from the outside will look completely black. Even if we paint the cube black, the hole will be blacker than the black cube. This hole will be an absolutely black body. In the literal sense of the word, the hole is not a body, but merely demonstrates to us an absolutely black body.

All objects have thermal radiation (while their temperature is above absolute zero, that is -273.15 degrees Celsius), but no object is an ideal thermal radiator. Some objects radiate heat better, others worse, and all this depending on various environmental conditions. Therefore, a model of an absolutely black body is used. Absolutely black body is an ideal thermal radiator. We can even see the color of an absolutely black body, if it is heated, and the color that we see will depend on the temperature to which we heat the absolutely black body. We came very close to such a concept as the color temperature.

Look at the picture (2).

Figure (2). - The color of an absolutely black body, depending on the temperature of heating.

a) There is an absolutely black body, we do not see it at all. Temperature 0 Kelvin (-273.15 degrees Celsius) is absolute zero, the total absence of any radiation.

b) Turn on the "super-powerful flame" and begin to heat our absolutely black body. Body temperature, by heating, increased to 273K.

c) A little more time has passed and we already see a faint red glow of an absolutely black body. The temperature increased to 800K (527 ° C).

d) The temperature rose to 1300K (1027 ° C), the body acquired a bright red color. You can see the same color of glow when some metals are heated.

e) The body was heated to 2000K (1727 ° C), which corresponds to the orange color of the glow. The same color has a red-hot coals in the fire, some metals when heated, a candle flame.

f) The temperature is already 2500K (2227 ° C). The glow of such a temperature becomes yellow. It is extremely dangerous to touch such a body with your hands!

g) White color - 5500K (5227 ° C), same color of glow at the Sun at noon.

h) The blue color of the glow is 9000K (8727 ° C). It is impossible to obtain such a temperature by heating with a flame in reality. But such a threshold of temperature is quite achievable in thermonuclear reactors, atomic explosions, and the temperature of stars in the universe can reach tens and hundreds of thousands of Kelvin. We can only see the same blue tint of light, for example, from LED lights, celestial bodies or other light sources. The color of the sky in clear weather is about the same color. Summarizing all of the above, you can give a clear definition of color temperature. Color temperature is the temperature of an absolutely black body, at which it emits radiation of the same color tone as the radiation in question. Simply put, the temperature of 5000K is a color that gets completely black body when it is heated to 5000K. The color temperature of the orange color is 2000K, which means that an absolutely black body needs to be heated to a temperature of 2000K, so that it gets an orange glow.

But the color of the glow of a red-hot body does not always correspond to its temperature. If the flame of the gas stove in the kitchen is blue-blue, this does not mean that the flame temperature is above 9000K (8727 ° C). The molten iron in the liquid state has an orange-yellow shade of color, which actually corresponds to its temperature, which is approximately 2000K (1727 ° C).

No matter how strange it may sound, the light has its own color temperature!

In your apartment, house, office or grocery supermarket across the road installed and lighting devices.

And from what color temperature they have. Depends on your perception of objects and even your mood.

Let's look at these numerical values.

- the people sound like warm glow or warm white.

-   it is naturally white, although many consider it a cold white or cold glow, although this temperature is closest to the morning sun and the sun at lunchtime. :).

-   bright white or close to daylight.

Fig. 1

  Fig. 2

In the interior and exterior use different types of lamps based on the tasks, conditions and personal preferences of a person.

In the classical interior design, mainly use warm or warm white light (2700K) for these needs are ideal. In the color temperature box, tick the " warm glow".

For a rapidly developing world, the temperature of the luminescence in 4000K-4200K is more and more suitable, so in Hi-tech design interiors naturally white light is used.

And for these purposes you have an excellent choice, and energy-saving lamps. Click on the links in the Color Temperature column to select the desired light.

   For offices, conference rooms, laboratories and for other high-precision works performed in the premises use bright white from 6000K and above.

With this glow, the brain and eyes are the most productive and effective.

Fig. 3

Video about the color temperature.

Color temperature is the most important characteristic of LED electrical products. It depends on how comfortable you feel in the interior, illuminated by LED lamps, ribbons or lamps.

The color temperature is measured in degrees Kelvin (K). According to European standards, all light sources by color are divided into three groups:

• warm white (Tc = below 3500 K)
• neutral white or daylight (Tc = 3500-5300 K)
• cold white (Tc = above 5300 K)

The color temperature of the usual incandescent lamp is approximately 2,800 K, so the warm white light of the LED lamps is most familiar to the eye (from 2700 to 3500K).

For most types of work and facilities are recommended "neutral" light sources (Tcv = 4000 - 4500 K). If we talk about the influence of color temperature on a person, warm light relaxes and creates an atmosphere of coziness, while colder tones help the body concentrate and adjust to the working mood.

Lighting jobs

In the workplace, the color temperature should be as close as possible to the color of natural light. If in white light (daylight) and long-term work of a person to take its production for 100%, then in the yellow light it will be only 93%, with green 92%, with blue 78%, with red and orange 76%. Those. at the workplace, daylight will be more useful (approximately 4000 - 4500 K).

For reading, the cooler white light (but only up to 6500 K) is useful:

  Color temperature in different rooms in the house

Although our eyes have for many years been accustomed to the soft white color temperature of incandescent lamps, this does not mean that they are necessarily the best option for lighting the entire house.   For example, because of their warm color temperature, these soft white lights often draw warm colors from the room (objects of red, orange), change the contrasts throughout the space.  AT from a few tips on how to most effectively illuminate the different rooms in your home:

Soft white / warm white (2700-3500K):

It is best suited for bedrooms and living rooms, creating a traditionally warm and cozy feel in these rooms. Also, soft light is good for lighting a dining table

Bright white / cold white (5300 - 6500 K):

Best suited in kitchens, bathrooms or garage, encouraging you, creating a more energetic mood.

Daylight (4000 - 5000 K):

Best suited in bathrooms, kitchens and cellars; ideal for reading, for working with complex projects, or for applying makeup - provides the greatest contrast between colors.

There is one more thing: the color temperature of your light source affects the perception of different colors in your interior.

When choosing lamps for the lighting of your home, we recommend that you pay attention to the indicator of their color temperature, since it depends not only on the brightness, but also on the shade of their glow. The same applies to the choice of car lamps, which guarantee safety to the driver and passengers when driving in the dark.

Safety of the driver during road traffic is provided by automobile lamps. On how optimal is the spectrum of their radiation, which provides good visibility on the road, the color temperature will say. This physical quantity is considered the main characteristic of the glow of automobile lamps. By the same principle, you should choose the light for the house. Lighting in residential and non-residential rooms can be arranged in warm and cold tones. With the help of various sources you can create an incredible play of light and provide an amazing atmosphere in any room. More details about all this, in our article.

What is this value?

The temperature of light, which is usually measured in kelvins, is the main light indicator of lighting engineering. It characterizes the features of its radiation and is responsible for the following characteristics:

• Spectral properties;
• Shade of luminescence;
• Light transmission index.

It equals the degree of heating of the ACT (an absolutely black body absorbing the radiation incident on it in all ranges). With the help of this indicator, for example, the color temperature of fluorescent lamps is measured. A hot solid object can protrude from the ACT. When the degree of its heating changes, the radiation spectrum will change - it will gradually change from blue to red when cooling and, conversely, from red to blue when heated. In this case, the shades of each other will be changed successively. The red shade will replace orange, orange - yellow, yellow - white. The temperature of the incandescent AFT corresponds to the blue luminescence radiation.

The color temperature of incandescent lamps does not exceed 3000 k. It is up to this indicator that its main working elements-threads, which provide them with a warm reddish hue are heated. By the same principle, the light characteristics of other light sources are established. Only in LED lamps this figure does not correspond to the level of their heating. Almost 3000 k will be already at incandescent of the LED to 80 degrees.

The radiation spectrum of the ACT becomes visible when the level reaches 1200 K, that is, the limits of warm red hues. Further, when heated to 2000 k, the red color of the radiation changes to orange, and when the figure reaches 3000 k, it turns yellow. This glow can be, as in warm, and in cold scale.

The maximum color temperature of incandescent lamps, in which the tungsten helix is ​​used as the working element, does not exceed 3500 K. But other light sources may well be heated further. For example, the color temperature of LEDs easily reaches 5500 k, at which they emit a saturated white color. And when it reaches a mark of 6000 k, their glow will turn slightly bluish. With further heating, the blue color of the radiation will become more and more saturated. And, as soon as its indicator reaches the level of 18,000 k, the radiation will reach the violet border of the spectrum.

How does the type of lighting depend on this indicator?

To illuminate homes and apartments, these days, there are special requirements, while attention is paid to the color perception of selected light shades. The same applies to the light of automobile headlights, which should not only be pleasing to the eye, but also clearly illuminate the road along the route of the car. As already mentioned above, the glow can be either warm or cold light range. Each light shade corresponds to a certain indicator. To learn the color temperature of 4000 to what color it will help our color temperature table.

This table will allow you to select the right lighting equipment in order to achieve optimal illumination of any room. But it should be borne in mind that the intensity of radiation, as well as the color temperature of the lamps, is perceived differently throughout the day.

At present, a huge number of lighting devices are equipped with LEDs, which provide them with a glow. What will be the color temperature of the LED lamps, the table below will clearly demonstrate.

LED lamps are widely used for indoor and outdoor lighting, as well as for light advertising and car headlights. The color temperature is used as the main indicator of brightness and the range of their luminescence.

Gradation of LEDs with white light

With all the shades of white luminescence is very in demand among consumers, due to its wide scope of use. LEDs have found their application in the design of photo studios, greenhouses, exhibition halls. They are used in various lighting devices for indoor and outdoor lighting, in New Year garlands, car headlights, etc.

The color temperature of the LEDs of cold white radiation lies in the range from 5000 to 7000 k. Their advantages include a high contrast, due to which they have become widely used in autolamps. But it should be borne in mind that cold white light very strongly distorts the color perception.

Neutral white light, which varies from 2500 to 6000k, is ideal for full illumination of small sections of the road. The same applies to automobile headlamps emitting warm white light. They are ideal for driving in difficult weather conditions - heavy rain, wind, fog. Their effectiveness is not lost and under water.

Color characteristics of autolamps

This indicator is extremely important when choosing autolamps. After all, from the properly selected near and far light depends on the safety of the driver and passengers during the movement of cars in the dark or in difficult weather conditions. To ensure the glow of automobile headlights, different types of lamps are used, their color temperature scale is given below:

• Halogen

3200 к - a standard shade of a glow of automobile headlights, ideally approaching for driving in a night-time and at a bad weather;

5000 k - natural white light, providing good coverage of the road surface during night trips.

• Xenon light

4500 к - optimum shades of a luminescence, ideally approaching for driving at a bad weather and at night;

6000 to - they emit natural daylight and are therefore great for use when driving in the dark.

• LED Light Bulbs

5000 k - a white color of increased brightness, which makes it possible to see well, not only the roadway, but also the markings applied to it;

6000 to - a rich white color with a slightly bluish tint, which simultaneously provides both practical and decorative function of the headlights.

8000 to - blue and blue-violet color is used exclusively for car decoration. It has low power and therefore can not be the only light source of automobile headlights.

10000 to - a rich blue-violet hue, they are used exclusively for show cars.

12000 к - blue glow with a light purple hue, banned for use during traffic. On the car, they can be installed at an exhibition or show-car to draw attention to his model.

What color of radiation of the head and peripheral optics of the car to choose, the motorist decides, depending on his individual preferences and the features of the car.

What is the color rendering index?

The color rendering index is another important indicator of the glow of all automobile lamps, which transmits the saturation of their light and perception by the human eye, depending on the color temperature. Here everything is very simple, the higher this indicator, the higher the color rendering index. This is well represented in the table.

To summarize, it should be noted that the color temperature is an important characteristic of all lighting fixtures and, in particular, automobile lamps. It is inextricably linked with the brightness of the glow and directly affects the perception of human eyes artificial light and the visibility of the roadway in the dark or in bad weather. The color rendering index of the LED lamps is always at an altitude.

For driving in the dark, it is better to use lamps whose luminosity is in the range from 4300 to 6000 k, and in case of heavy rain, haze or fog, it is better to use those light sources whose index lies in the range of 2400 to 3200 k. Excellent color rendition is provided by all types of modern lamps - halogen, xenon and LED. They will create optimal lighting in your house, ideal for emphasizing all the strengths of a home interior and hiding the possible shortcomings of its design. This indicator is available on all modern light bulbs, so you will not be able to choose an appropriate variant of labor for an average user.