What is the color temperature of the lamps. Colorful temperature

There is an opinion that artificial lighting is “warm” and “cold”. We are talking, first of all, about the shades of lighting fixtures on cars. The concept of "color temperature" (or "temperature of light") actually has importance when installing the lighting system of the machine. Today we will try to figure out what the color temperature of LED lamps is, how it is measured and how it affects the level of illumination.

What does this concept mean?

Until recently, automotive lighting was organized by halogen lamps. Today, they have been replaced by more powerful and better light sources in terms of lighting characteristics - diode lamps. They are used everywhere:

  • home and business lighting;
  • lighting device on various vehicles (cars, motorcycles, ATVs, etc.);
  • design of outdoor advertising stands;
  • use in searchlights of street and office lighting devices.

What is the color temperature of LED lamps? This concept does not even imply the amount of heat they emit, but has a slightly different meaning. If to speak plain language, that is visual effect perception of a light source by the human eye. The "warmth" of each source is determined as the hue spectrum approaches the solar (yellow).


Luminescence spectrum with indication of each source

To better understand this concept, you can make an association with the flame of a candle. If we are talking about cold shades, then there is more association with the color of the sky at different times of the day. Or here's another, during the heating of the metal, it emits a characteristic glow. At first, this process is accompanied by red tones. With an increase temperature regime the color spectrum gradually begins to shift towards yellow, white, bright blue and purple.

How is this feature measured? The very understanding of temperature implies that it is clearly measured in degrees. In this case, we are talking about Kelvin., which are abbreviated with the capital letter "K".

For greater perception, consider the color temperature of LED lamps in the table, where each value corresponds to specific color observed by us in everyday life and in life.

t°, Kelvin

light emitter

The first stage of the visible dark red glow of hot metal bodies

The glow of a candle flame

40W incandescent lamp

LN with a power of 100W

LN power at 200W, halogens

The glow of the sun on the horizon

Lamps daylight(LDS)

The glow of the sun in the morning and afternoon

Arc lamp on xenon, electric arc

The glow of the sun at noon

Flash light

close to DS

Close to noon solar

Cloudy weather

DS, dominated by scattered clear blue skies

dusk glow

Blue sky with no clouds on the north side just before sunrise

Light source with "infinite t°"

clear sky in winter time of the year

Blue skies in regions close to the Arctic Circle

The light color temperature of LED emitters is slightly different. In contrast to the glow spectrum of a metal when it is heated, it has a slightly different form of emitted radiation. luminous flux, which is due to a different method of origin. But at the same time, the general essence remains the same: in order to obtain the required shade, a certain t° of light emission is required. It is also worth noting the fact that this characteristic is in no way related to the amount of thermal energy released by the light element.

Once again, it is worth recalling that color temperature and physical concepts are not identical. In the first case, we are talking about the brightness of the light flux, in the second - about the amount of heat generated.

VIDEO: The Science of Light Temperature

Color degree of LEDs

The modern domestic market offers wide choose sources of light emission on LED-type crystals. All of them are designed to work in different temperature ranges. As a rule, they are chosen depending on the place of the intended installation, since each light element creates its own, individual glow. In the same room, you can create different lighting using different lighting elements.


Distribution of light sources on the color temperature scale

For the optimal use of each individual light emitter, it is necessary to determine in advance which color will be most suitable for the implementation of the goal. The concept of t ° light radiation is in no way connected specifically with LED emitters, it is not tied to any particular light element, it depends solely on the spectral composition of the selected radiation.

Any light-emitting element used to have a color temperature, just in the production of standard incandescent lamps, their luminous flux was only “warm” yellow.

As soon as fluorescent and halogen lighting came into use white, "cold" light. LEDs are characterized by an even wider spectrum of color temperature radiation, which to some extent complicates independent choice most suitable option light flux. And all the shades of such a source began to be determined by the consumables from which the semiconductor was made.

What is a color rendering index?

The luminous flux in luminaires of any configuration and purpose can change the indicators of brightness and color saturation. This phenomenon in science is called metamerism.

Each light emitting element has a certain color rendering index, which is indicated on the packaging by the CRI (or R_a) index. This parameter determines its ability to accurately convey the colors of the light flux, which is produced by the light element.

If we are talking about a car lighting device, then diodes with a color rendering index of 80R and higher will work best. This will create the most clear cut-off line.

The table below helps you figure out which color corresponds to a particular color rendering index.

Quality Compliance

Color rendering index

Light fixture example

Light elements with filament, halogens

Excellent

Luminescent with 5-component phosphor, MGL (low-halogen), modern models LED

Very good

Fluorescent with 3-component phosphor, modern models of LEDs

Luminescent LBTs, LDTs, LEDs

Luminescent LD, LB, LEDs

below average

DRL (on mercury), NLVD with improved color rendering

DNAt (sodium)

For reference! different types lighting products, having identical tint t °, can render shades in different ways. The color rendering index determines the degree of deviation of the color of objects or objects of illumination from their true color when illuminated by one or another light source.

Indicators of xenon lamps

The very terminology regarding xenon sources remains exactly the same, but there is a slightly different gradation of the color of the glow, where the t ° of the Sun, which is 5000 ° K, is taken as a reference.


Color:

  • 3000°K - yellow;
  • 4300°K - light yellow;
  • 5000°K - white;
  • 6000°K - cold white with a slight addition of blue;
  • 8000°K - blue;
  • 10000°K - blue;
  • 12000°K - violet;
  • from 15000°K and above - all shades of pink.

The most optimal parameters for the vehicle will be from 4300 to 6000°K in a gradient from warm yellow to cold white.

Use xenon lamps without an auto-corrector is prohibited by the Code of Administrative Offenses of the Russian Federation and is considered by employees and courts as an incorrect use of the head lighting of a car, which can lead to the creation of an emergency situation on the road.

Now you know how warm is different White color from cold blue. Based on this information, you can right choice when organizing the lighting of a car or a room.

VIDEO: White LED Spectrum Analysis

One of the most important parameters LED lamp- this is the color temperature of the lamp, which for LED-devices fluctuates quite wide range. This term refers to the temperature at which monochrome black body begins to emit a glow of a certain spectrum (corresponding in shade to the lighting that this lamp creates).

The lower the color temperature, the warmer the shade of its glow. For example, for a candle flame, this indicator is 1500-2000 K, for an incandescent lamp - 2700 K, and for the so-called cold daylight lamps - 6000 K and above. To select a lighting fixture based on its color temperature, it is important to know information about it.

How does this indicator affect the perception of objects?

Modern manufacturers produce LED lamps with different color temperatures. All of them create different lighting, the properties of which can be used with purpose. Warm reddish-yellow, pale golden or bluish-white glow affects the visual perception of space, as well as emotional condition, into which a person enters while in this room.


By choosing the right color temperature for an LED lamp, you can increase the visual appeal of the product and increase the willingness of buyers to make a purchase. In museums competently organized lighting emphasizes all shades of color and features of the texture of the exhibit, which also attracts visitors. V in public places white light of different color temperatures helps to create the right environment for the morning, afternoon or evening.


The choice should be made in accordance with the task assigned to the lighting system:

    2700 K. Devices with this indicator create a cozy, warm lighting. Recommended for installation in restaurants, salons, hotel lobbies, and residential areas.

    3000 K. It is a near-neutral white light with a slightly yellowish tint. Suitable for creating an intimate friendly atmosphere in the room. Lamps with this color temperature are mounted in offices, shops, libraries.

    3500 K. Pure neutral light, in which the environment seems safe and inviting to a person. Such lighting devices are also good for offices, they are often installed in exhibition halls, bookstores, cinema foyers.

    4100 K. It's more invigorating cold light. It will be appropriate where it is required to provide a productive atmosphere, as well as a good color perception items. It is this color temperature that LED lamps installed in large supermarkets often have, medical centers, training rooms.

    5000-6000K. If the lighting fixture produces a sharp white light close to daylight, then its color temperature is most likely in this range. Ophthalmologists do not recommend staying under such lighting for a long time and warn against using this type of LED lamp in the evening or at night. But for medical examinations, art galleries, museums and jewelry stores, cold daylight will be in place. It perfectly conveys all shades of colors, provides good visibility of objects and the environment.

Can LED lamp give a glow of different temperatures?

Some manufacturers have launched the production of lighting structures that emit a glow of different color temperatures. Their device allows you to adjust the shade of light in accordance with specific situation. This is very convenient and physiological, since warmer yellow lighting will be natural for the morning hours, and during the day you can eliminate the lack of light coming from the windows. artificial lighting a similar tone, if necessary for work, reading or creativity.

range. According to Planck's formula color temperature is defined as temperature absolutely black body, at which it emits radiation of the same color tone, which is the radiation under consideration. It characterizes the relative contribution of the radiation of a given color to the radiation of the source, the visible color of the source. It is used in colorimetry, astrophysics (when studying the distribution of energy in spectra of stars). measured in kelvins and miredah.

Color temperature of some light sources

Colorful temperature electric lamps.

Color temperature scale of common light sources

  • 800 K - the beginning of the visible dark red glow of hot bodies;
  • 1500-2000 K - flame light candles ;
  • 2800 K - incandescent lamp 100 W (vacuum lamp);
  • 2800-2854 K - gas-filled incandescent lamps with tungsten spiral;
  • 3200-3250 K - typical filming lamps;
  • 3800 K - lamps used to illuminate meat products in a store (they have a high content of red in the spectrum);
  • 4200 K - daylight lamp(warm white light);
  • 4300-4500 K - morning sun and afternoon sun;
  • 4500-5000 K - xenon arc lamp , electric arc ;
  • 5000 K - Sun at noon;
  • 5500 K - clouds at noon;
  • 5500-5600 K - flashlight ;
  • 5600-7000 K - daylight lamp ;
  • 6200 K - close to daylight;
  • 6500 K - standard source of daylight white light, close to midday sunlight;
  • 6500-7500 K - cloudy;
  • 7500 K - daylight, with a large proportion of diffuse from pure blue sky ;
  • 7500-8500 K - twilight;
  • 9500 K - blue cloudless sky on the north side before sunrise;
  • 10,000 K - "infinite temperature" light source used in reef aquariums (actinium shade of blue);
  • 15000 K - clear blue skies in winter;
  • 20000 K - blue sky in polar latitudes;

Fluorescent lamps

Typical color temperature ranges at maximum light output of modern fluorescent lamps with multilayer phosphor :

  • 2700-3200 K,
  • 4000-4200 K,
  • 6200-6500 K,
  • 7400-7700 K.

Application

  • characterizes the spectral composition of the light source radiation,
  • is the basis for the objectivity of the impression of the color of reflective objects and light sources.

For these reasons, it determines the perceived by the eye color objects when observed in a given light (psychology of color perception).

Light sources in printing

To obtain the most correct color image at all stages of production, it is often recommended to maintain a standard color temperature of lighting of 6500 K (source D 65): from order acceptance through evaluation of originals, scanning, retouching, screen proofing, digital proofing, color separation, analog proofing, proofing , to the printing of the circulation and the final delivery of printed products.

Source D 65 with a color temperature of 6500 K has in its spectrum defined by the standard ultraviolet component. Although human eye does not perceive ultraviolet rays, many objects (including dyes) are able to glow under their action. For example, without the UV component, the paper will not be as white (optical brighteners are introduced into it), and advertising will not be so bright (it is often used in

Introduction………………………………………………………………………… 1. The concept of color temperature…………………………………………… ….. 1.1. Table of numerical values ​​of the color temperature of common light sources………………………………………………………………….. 1.2. XYZ Chromaticity Diagram………………………………………………….

1.3 Sunlight and Color Rendering Index (CRI - color rendering index)..

2. Methods for measuring color temperature………………………………...... Sources of information…………………………………………………………….

Introduction.

According to our psychological sensations, colors are warm and hot, 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 thermal radiation. Even ice, which has a negative temperature, is a source of thermal radiation. It's hard to believe, but it's true. In nature, the temperature of -89 ° C is not the lowest, you can reach even more low temperatures, however, so far, in laboratory conditions. The lowest temperature that is currently theoretically possible within our universe is the temperature of absolute zero and it is equal to -273.15 ° C. At such a temperature, the movement of the molecules of a substance stops and the body completely ceases to emit any radiation (thermal, ultraviolet, and even more so visible). Complete darkness, no life, no warmth. Perhaps some of you know that color temperature is measured in Kelvin. Those who bought energy-saving light bulbs for their home saw the inscription on the package: 2700K or 3500K or 4500K. This is exactly the color temperature of the light emitted by the light bulb. But why is it measured in Kelvin, and what does Kelvin mean? This unit of measurement was proposed in 1848. William Thomson (aka Lord Kelvin) and officially approved in the International System of Units. In physics and sciences directly related to physics, thermodynamic temperature is measured just by Kelvin. The beginning of the temperature scale report starts from the point 0Kelvin, which means - 273.15 degrees Celsius. That is, 0K is the absolute zero temperature. You can easily convert the temperature from Celsius to Kelvin. To do this, simply add the number 273. For example, 0 ° C is 273 K, then 1 ° C is 274 K, by analogy, a human body temperature of 36.6 ° C is 36.6 + 273.15 = 309.75 K. This is how it all works out.

Chapter 1. The concept of color temperature.

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

Light sources are bodies heated to high temperatures, the thermal vibrations of atoms of which cause radiation in the form electromagnetic waves different lengths. Radiation, depending on the wavelength, has its own color. At low temperatures and, accordingly, at longer wavelengths, radiation with a warm, reddish color of the light flux prevails, and at higher temperatures, with a decrease in wavelength, with a cold, blue-blue color. The unit of wavelength is nanometer (nm), 1nm=1/1,000,000mm. Back in the 17th century, Isaac Newton, using a prism, decomposed the so-called white daylight and obtained a spectrum consisting of seven colors: red, orange, yellow, green, blue, indigo, violet, and as a result of various experiments he proved that any spectral color can be obtained by mixing light fluxes, consisting of various ratios of three colors - red, green and blue, which were called the main ones. This is how the three-component theory appeared.

The human eye perceives the color 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, the light receivers of information carriers - cinema and photographic film or a camera matrix must have an identical color sensitivity to the eye. Sensitized films and matrices of video cameras perceive electromagnetic waves in a slightly wider range, capturing infrared radiation (IR) close to the red zone in the range of 780-900 nm and close to violet - ultraviolet (UV) radiation in the range of 380-300 nanometers. This region of the spectrum, in which geometric optics and light-sensitive materials operate, is called the optical range.

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

The heated body, depending on the heating temperature in its radiation, has a different ratio of different wavelengths and, accordingly, a different color of the light flux. The standard by which the color of radiation is determined is an absolutely black body (black body), the so-called. Planck emitter. An absolutely black body is a virtual body that absorbs 100% of the light radiation incident on it, and is described by the laws of thermal radiation. And the color temperature is the temperature of the black body in degrees Kelvin, at 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 starting point in the Kelvin scale is the temperature at which any movement of atoms in the body stops and, accordingly, any radiation stops , the so-called absolute zero, corresponding to a temperature in Celsius of -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 light sources - fire in the form of a fire, matches, torches and lighting devices, ranging from household appliances, technical devices and ending with professional lighting devices designed specifically for cinema and television. Both in household appliances and in professional ones, various lamps are used (we will not touch on their principle of operation and design differences) with different energy ratios in their emission spectra of the primary colors, which can be expressed by the color temperature value. All light sources are divided into two main groups. The first, with a color temperature (Tcv.) 5600 0K, white daylight (DS), the radiation of which is dominated by the short-wave, cold part of the optical spectrum, the second - incandescent lamps (LN) with Tcv. - 32000K and the predominance of long-wave, warm part in the radiation optical spectrum.

Where does it all begin? Everything starts from scratch, including light emission. Black is the absence of light at all. In terms of color, black is 0 light intensity, 0 saturation, 0 hue (it just doesn't exist), it's the complete absence of all colors at all. Why do we see an object as black, but because it almost completely absorbs all the light falling on it. There is such a thing as a completely black body. A black body is an idealized object that absorbs all radiation falling on it and reflects nothing. Of course, in reality this is unattainable and absolutely black bodies do not exist in nature. Even those objects that seem black to us are actually not completely black. But it is possible to make a model of an almost completely black body. The model is a cube with a hollow structure inside, a small hole has been made in the cube through which light rays penetrate into the cube. The design is somewhat similar to a birdhouse. Look at the picture (1).

Picture 1). - Model of a completely black body.

Light entering through the hole will be completely absorbed after repeated reflections, and the hole will look completely black from the outside. Even if we paint the cube black, the hole will be blacker than the black cube. This hole will be a completely black body. In the literal sense of the word, the hole is not a body, but only clearly demonstrates to us a completely black body.

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

Look at the picture (2).


Figure (2). - The color of a completely black body depending on the heating temperature.

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

b) We turn on the “super-powerful flame” and begin to heat up our absolutely black body. Body temperature, through heating, increased to 273K.

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

d) The temperature rose to 1300K (1027°C), the body became bright red. You can see the same glow color when heating some metals.

e) The body is heated to 2000K (1727°C), which corresponds to the orange color of the glow. Hot coals in a fire have the same color, some metals when heated, a candle flame.

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

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

h) Blue glow color - 9000K (8727°C). In reality, it will be impossible to obtain such a temperature by heating with a flame. But such a temperature threshold is quite achievable in thermonuclear reactors, atomic explosions, and the temperature of stars in the universe can reach tens and hundreds of thousands of Kelvins. We can only see the same blue tint of light from, for example, 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, we can give a clear definition of color temperature. Color temperature is the temperature of a completely black body at which it emits radiation of the same color tone as the radiation in question. Simply put, a temperature of 5000K is the color that a completely black body acquires when it is heated to 5000K. Colorful temperature orange color- 2000K, this means that a completely black body must be heated to a temperature of 2000K in order for it to acquire an orange glow.

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

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