Luminosity is a unit of measurement of illumination. The number of lumens in the lamp and its luminous flux. Visible and optical radiation
We are looking at the popular questions about the light di-one lights and de-we-we-we-e-ing the myths in- circle on-nya-tiya “lu-men”.
IN Lately We hear more and more questions:
How many lumens are in an incandescent lamp?
How many lumens are in a light bulb?
How many lumens does the lamp have?
How many lumens are in an LED lamp?
How many lumens in 1 watt LED lamp?
How to determine the luminous flux of a lamp?
Which LED bulbs Are they similar to incandescent bulbs?
Let's try to figure it out. First, let's answer the question: what is lumen?
Lumen- this is a unit of measurement of the luminous flux of a light source, in our case, the light source will be an LED lamp, an incandescent lamp, the LED itself or any other lamp.
We have prepared a comparison table of the ratio of luminous flux (lumens) to luminaire power (W) for LED lamps, incandescent and fluorescent lamps.
|
incandescent lamp, |
Fluorescent Lamp, |
LED lamp, |
Luminous flux, Lm |
| 20 W | 5-7W | 2-3W | About 250 lm |
| 40 W | 10-13 W | 4-5W | About 400 lm |
| 60 W | 15-16 W | 8-10 W | About 700 lm |
| 75 W | 18-20 W | 10-12 W | About 900 lm |
| 100 W | 25-30W | 12-15W | About 1200 lm |
| 150 W | 40-50W | 18-20 W | About 1800 lm |
| 200 W | 60-80W | 25-30W | About 2500 lm |
As can be seen from the table, on average, LED lamps are 10 times more efficient than incandescent lamps, and fluorescent lamps are 2 times more efficient.
It is worth noting that the LED, and therefore the LED lamp, emits directional light, unlike incandescent lamps and fluorescent lamps, which means that the direct illumination from the LED lamp will be higher. When using LED lamps as spot lighting, the efficiency of such lighting will be higher compared to analogues.
How many lumens in a 1W LED light bulb?
The luminous flux of modern LEDs varies from 80 to 150 lm with 1 watt. This is due to differences in cooling systems and current-voltage characteristics of the LEDs themselves.
For experimental LEDs, the luminous flux can reach up to 220 Lm / W, but in practice, lamps with such indicators are not yet produced.
How to determine how many lumens are in our light bulb or lamp?
The luminous flux is indicated on the box or in the specification for the product. You can also use the comparison table above.
If we want to determine for ourselves, then we need to use a light meter and determine the illumination at each point in the room. Lux is the ratio of the number of lumens per illuminated area (1 lux is 1 lumen per square meter). The total luminous flux created by an isotropic source with a luminous intensity of 1 candela is 4π lumens.
What is luxury?
Suite is a unit of measure for illumination. Lux is equal to the illumination of a surface of 1 sq.m. with a luminous flux from a source of 1 lm.
In practice, the main value is the indicator of illumination on the working surface, measured in Lx (Lux) using a special device - a luxmeter. Moreover, the illumination of work surfaces and rooms for various areas activities must comply with state standards specified in SNiP 05/23/2010.
How many lumens are there in a lamp with a DRL lamp, DNAt and LEDs?
The luminaire, unlike the lamp, has an optical system for more efficient use of the luminous flux. In cheap luminaires that do not have special reflectors and high-quality diffusers, the luminous flux when using powerful DRL and Dnat lamps is much lower and can drop to 50-60% of the total luminous flux of an individual lamp, while for LED luminaires with a more directional luminous flux, these losses will be much less - up to 5% depending on the optical system.
| Lamp with DRL lamp | Lamp with lamp Dnat | LED lamp | Luminous flux, Lm |
| 125 W | 70 W | 30-40W | About 3,500 lm |
| 250 W | 100 W | 40-60W | About 8,000 lm |
| 400 W | 150 W | 80-120W | About 12,000 lm |
| 700 W | 250 W | 140-160W | About 20,000 lm |
| 1000 W | 400 W | 180-200W | About 30,000 lm |
*Approximate ratios based on Dialux calculations.
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- (from lat. lumen light) (lm, 1t), SI unit of luminous flux; 1 lm luminous flux emitted by a point source in a solid angle of 1 steradian at a light intensity of 1 candela. Physical Encyclopedic Dictionary. M.: Soviet Encyclopedia. Main… … Physical Encyclopedia
LUMEN- unit of measurement of the luminous flux; abbreviated Russian designation lm, international lm. A luminous flux of 1 lm will pass through 1 m2 of a spherical surface with a radius of 1 m, if a light source in one candle is placed in the center of this surface. ... ... Brief Encyclopedia household
- (from lat. lumen light) SI unit of luminous flux; denoted lm. 1 lm luminous flux emitted by a point source in a solid angle of 1 sr at a light intensity of 1 candela ... Big Encyclopedic Dictionary
- (designation lx or lm), a unit of luminous flux in the SI system. Lumens measure the amount of visible light emitted in one second into a single spatial angle (one steradian) from a source of a single power (one CANDELA) ... Scientific and technical encyclopedic dictionary
An international unit of measurement for luminous flux (see), equal to the luminous flux emanating from specially designed incandescent lamps stored in reference laboratories. Samoilov K.I. Marine Dictionary. M. L .: State Naval ... ... Marine Dictionary
Unit of measure for luminous flux. The total luminous flux emitted in all directions by a light source with a power of 1 candle is 12.56 L. Its value is determined by reference electr. incandescent lamps, manufactured as precisely as possible, ... ... Technical railway dictionary
Exist., number of synonyms: 2 asteroid (579) unit (830) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary
lumen- lm - [Ya.N. Luginsky, M.S. Fezi Zhilinskaya, Yu.S. Kabirov. English Russian Dictionary of Electrical Engineering and Power Industry, Moscow, 1999] Electrical engineering topics, basic concepts Synonyms lm EN lumenlm ... Technical Translator's Handbook
Lumen- Lumen (lm) - a unit of measurement of the luminous flux, which, with a light intensity of 1 sv, is evenly emitted inside a solid angle of 1 ster. [Glossary of basic terms required in the design, construction and operation of automotive ... ... Encyclopedia of terms, definitions and explanations building materials
- (lat. lumen light) a unit of luminous flux in the international system of units (si), equal to the luminous flux emitted by a point source in a solid angle of 1 steradian at a light intensity of 1 candela; abbr. designations: lm, 1t. A new dictionary of foreign ... ... Dictionary of foreign words of the Russian language
Many buyers of our online store who want to buy projectors are interested in the question - how is the brightness of these devices measured? IN technical specifications you can meet two, or even three units of measurement - lumens, ANSI lumens, "brightness by color." And the difference between these values of the most important parameter for the projector can be quite significant. In this article, you will learn why this happens and how the ANSI lumen differs from the "Chinese" lumen.
What is a lumen?
This is the standard (SI) unit of measurement of luminous flux, adopted in physics. The standard Russian designation is lm, foreign - lm. We can talk about luminous flux only in the context of a light source, for example, a conventional lamp with a 100 W incandescent spiral has a luminous flux of 1340 lm, and a 200-watt lamp has 3040 lumens. Physical lumens have nothing to do with the brightness of projectors.
ANSI lumen, which is no lumen at all
When it comes to such a device as a projector, it is not so much the brightness of the light source that matters, but the overall illumination of the screen and the perception of this illumination. After all, each projector has its own optics. And in the USA, in an organization called the American National Standards Institute, back in 1992, they came up with a new unit of measurement with which you can rank projectors.
They called this new unit of measurement the ANSI lumen, and it remains on the conscience of the American Institute. The ANSI lumen is calculated as follows - the projector illuminates with a completely white picture (Full-White) a 40-inch screen located at a distance of several feet, then using a special high-precision "luxmeter" device, the illumination is determined at several control points (in 9 , to be precise). Then the average value is taken and multiplied by the area in square feet.
This value is called ANSI-lumen, it is customary to designate “brightness of projectors” by it. As you understand, the ANSI lumen has nothing to do with the scientific unit of measurement, the SI lumen. The luxometer measures the illumination of the surface in "lux", and the unit of measurement of physical brightness (not luminous flux, but brightness) is candela / m 2.
Peak lumens - Peak Lumens ("Chinese")
Apparently, in order to further confuse our customers, manufacturers from China and Japan use their alternative unit for measuring the "brightness" of projectors - Peak lumens or "peak lumens". The measurement determines the illuminance of the screen onto which the projector projects a test pattern, where 20% of the screen is lit in the center and the rest is dark. Since this is the most illuminated part of the screen, peak brightness is approximately 10-12 times ANSI lumens.
Moreover, in the technical specifications, this value is given simply in "lumens". And so, if you read 30,000 lumens in the specifications of a Chinese projector, then that most likely means no more than 300 ANSI lumens. Large manufacturers report the results of both tests - we understand that lumens and ANSI lumens can only be determined empirically. For example, the Everycom BT96 projector produces 3000 "peak" lumens, which corresponds to 350 ANSI lumens (according to the manufacturer).
Color Light Output - Brightness By Color
This is a recently appeared unit of measurement for the brightness of projectors, which today is indicated along with ANSI lumens. The bottom line is that when measuring, the illumination is determined by red, green and blue color, also by 9 points. Yes, CLO is also measured in lumens. It is believed that the ANSI lumens and CLO should be the same, usually they write so in the characteristics.
How to choose a home theater projector or "brightness race"
When choosing a projector, remember that the brightness of the projector is very important, but it is not decisive. It sounds a little strange, but in fact it is - we told above how ANSI lumens and peak lumens are measured, but in fact these are only the readings of a small device, which, I want to believe, was in the hands of honest and unbiased experimenters, and the projector has been correctly adjusted. And the perception of the picture depends on many things, for example, on the technology of the matrix. Sometimes you don't want to look at a very bright image.
Top manufacturers are running a "lumen race" today, and interested commercial writers are instilling in buyers - "the more the better", "the brightness of a modern home theater projector should be at least 4000 ANSI lumens"! For example, the $500 Epson EB-X04 EEB (H717B) claims a brightness of 2800 ANSI lumens. But, at the same time, when the Chinese XGIMI launched its H1 model home theater projector for $800 on the crowd crafting platform (you can buy this projector in our store via this link), tens of thousands of customers around the world rushed to order this device. Although its claimed brightness is only 900 ANSI lumens. And today this more expensive, seemingly “less bright” projector is very popular all over the world, shipped in thousands of units per day.
It's safe to say that for home use, 500-1000 ANSI lumens will be more than enough brightness. For educational purposes in small spaces, 1500 ANSI Lumens is enough. For displaying video on a large screen and in an equally large, unshaded room comparable to a movie theater, projectors with a brightness of 4000-7000 ANSI-lumens are suitable for you.
Professional lighting technicians and specialists working in the field of lighting constantly use different terms and definitions that mean little to the average layman.
To make it easier to understand what we are talking about and what these words mean, we have prepared a list explaining the main lighting terms and characteristics. It does not need to be learned by heart, you can simply go to the desired page and refresh the forgotten parameter in your memory. Speaking "in the same language" is always easier.
Lighting parameters and concepts.
1 - Visible and optical radiation
The entire world around us is formed by visible radiation concentrated in the band of electromagnetic waves from 380 to 760 nm. Ultraviolet radiation (UV) is added to it on one side, and infrared (IR) on the other.
UV rays have a biological effect and are used to kill bacteria. Dosed they are used for therapeutic and healing effects.
IR rays are used for heating and drying in installations, as they mainly produce a thermal effect.
2 - Luminous flux (F)
The luminous flux characterizes the power of visible radiation by its effect on human vision. measured in lumens(lm). The value is independent of direction. Luminous flux is the most important characteristic.
For example, an E27 75 W incandescent lamp has a luminous flux of 935 lm, a 75 W halogen G9 - 1100 lm, a 35 W T5 fluorescent lamp - 3300 lm, a 70 W metal halide G12 (warm) - 5300 lm, an E27 LED 9.5 W ( warm) - 800 lm.
3 - Lumen
Lumen (lm) is the luminous flux from a light source (lamp) at ambient temperature 25° measured under reference conditions.
4 - Illumination (E)
Illumination is the ratio of the luminous flux supplied to a surface element to the area of this element. E \u003d F / A, where, A is the area. Illumination unit - luxury(OK).
Most often, horizontal illumination is normalized (on a horizontal plane).
Average illumination ranges: outdoors under artificial lighting from 0 to 20 lux, indoors from 20 to 5000 lux, 0.2 lux during the full moon in natural conditions, 5000 -10000 lux during the day with clouds and up to 100,000 lux on a clear day.
The picture shows: a - the average illumination on the area A, b - the general formula for calculating the illumination.
5 - Strength of light (I)
The intensity of light is the spatial density of the luminous flux limited by a solid angle. That is, the ratio of the light flux emanating from a light source and propagating inside a small solid angle containing the direction under consideration.
I \u003d F / ω The unit of measurement of luminous intensity is candela (cd).
The average luminous intensity of a 100 W incandescent lamp is about 100 cd.
KSS ( light intensity curve) - the distribution of light intensity in space, this is one of the most important characteristics lighting fixtures, necessary for the calculation of lighting.
6 - Brightness (L)
Brightness (light density) is the ratio of the luminous flux carried in an elementary beam of rays and propagating in a solid angle to the cross-sectional area of a given beam.
L=I/A (L=I/Cosα) Luminance unit - cd/m2.
Brightness is related to the level of visual sensation; The distribution of brightness in the field of view (indoors/interiors) characterizes the quality (visual comfort) of lighting.
In complete darkness, a person reacts to a brightness of one millionth of a cd / m2.
A fully luminous ceiling with a brightness of more than 500 cd / m2 causes discomfort in a person.
The brightness of the sun is about a billion cd/m2, and fluorescent lamp 5000–11000 cd/m2.
7 - Light output (H)
The luminous efficacy of a light source is the ratio of the luminous flux of a lamp to its power.
Η=F/R The unit of measure for light output is lm/W.
This is a characteristic of the energy efficiency of the light source. Lamps with high luminous efficiency provide energy savings. Replacing an incandescent lamp with a light output of 7–22 lm/W with fluorescent ones (50–90 lm/W), the power consumption will decrease by 5–6 times, and the illumination level will remain the same.
8 - Color temperature (TC)
Color temperature determines the color of light sources and the color tone of the illuminated space. The color temperature is equal to the temperature of a heated body (Planck emitter, black body), the same color as a given light source.
The unit of measurement is Kelvin (K) on the Kelvin scale: T - (degrees Celsius + 273) K.
Candle flame - 1900 K
Incandescent lamp - 2500–3000 K
Fluorescent lamps - 2700 - 6500 K
Sun - 5000–6000 K
Cloudy sky - 6000–7000 K
Clear day - 10,000 - 20,000 K.
The color rendering index characterizes the degree of color reproduction various materials when illuminated by a light source (lamp) when compared with a reference source.
The maximum value of the color rendering index is Ra =100.
Color Rendering Ratings:
Ra = 90 or more - very good (color rendering 1A)
Ra = 80–89 - very good (color rendering 1B)
Ra \u003d 70–79 - good (color rendering degree 2A)
Ra \u003d 60–69 - satisfactory (color rendering degree 2B)
Ra \u003d 40–59 - sufficient (color rendering degree 3)
Ra = less than 39 - low (color rendering 3)
Ra he is CRI- The color rendering index was designed to compare continuous spectrum light sources whose color rendering index was greater than 90, since below 90 it is possible to have two light sources with the same color rendering index but with very different color rendering.
Comfortable for the human eye CRI value = 80–100 Ra
In order to quickly and efficiently perform any production task, the lighting of the specialist’s workplace must be properly organized. For this, lamps with certain photometric indicators are selected.
Lighting in the workplace is determined by various physical quantities, the main of which is illumination. Its indicators are calculated for the workplace of any specialist and are regulated by the relevant SNiPs.
Illumination is a characteristic that is defined as the luminous flux per unit area.
Luminous flux (F)
This physical parameter is defined as the power of the visible radiation of the source or the light energy that is emitted by the luminaire per unit of time.
At the same time, light energy is an energy that spreads in all directions and causes visual sensations. Each person has different visual sensations for the same radiation sources, therefore, averaged indicators are taken for calculations.
In physics, the formula is used to calculate:
F \u003d W / t, where:
- W is the energy emitted by the source, measured in watts,
- t is the device operation time in seconds.
It is also a value that characterizes the amount of light emitted by a lighting fixture in all directions.
Thus, the second calculation formula looks like:
Ф = I w, where:
- I - light intensity, measured in candela,
- w is the solid angle, calculated in steradians.
Lumen
The unit of measure for luminous flux is lumen.
In order to determine which source is more profitable to purchase, we first consider what a lumen is.
The word lumen in Latin means light.
A lumen is defined as the luminous flux that is emitted by a point source having a luminous intensity of 1 candela into a solid angle of 1 steradian:
1lm = 1W / 1s.
On the other side,the unit of measure lumen (lm) can be found as:
1 lm \u003d 1 cd 1 sr.
If the solid angle is 4π radians, and the luminous intensity is 1 cd, then in this case they talk about the total luminous flux, which is 4π lm or 4 3.14 lm.
It was calculated that this indicator for solar radiation corresponds to 8 lm, and for the starry sky - only 0.000000001 lm.
For any artificial light source, there are tables for calculating this photometric parameter.
In lighting engineering, derivative quantities are used, which are formed using standard prefixes of the international SI system, for example:
- 1 klm = 103 lm or 1 klm = 103 lm;
- 1 Mlm = 106 lm;
- 1 slm = 10-3 lm;
- 1 µlm = 10-6 lm.
Measuring instruments
To measure photometric quantities in industry, special devices are used, which are called spherical photometers and goniophotometers. They allow you to determine both the luminous flux and the intensity of light from various lamps.
Photometers are visual and objective.
The principle of operation of visual instruments is based on the ability of the eye to determine the same brightness of the illumination of two compared surfaces illuminated with the same color.
Currently, objective electric photometers are popular, which allow measuring light parameters not only in the visible zone, but also beyond it.
Goniophotometers allow obtaining data on the magnitude of the luminous flux, luminous intensity, as well as indicators of other photometric quantities, such as brightness, illumination distribution, etc.
Recommendations for organizing the right workplace lighting
When lighting workplaces, two types of sources are used: artificial and natural.
Artificial are devices with lamps various types: fluorescent, incandescent, LED, etc.
For each type of lamp there are tables indicating the number of lumens emitted by this lamp.
This value is indicated on the packaging of the product, so when buying, be sure to select a light bulb, guided by the information placed by the manufacturer on the box. The packaging of the luminaire indicates the total luminous flux, which includes diffused light.
Attention! When purchasing a lamp, it is important to remember that this indicator does not fully reflect its brightness, since it can be increased through the use of a system of reflectors, lenses and mirrors placed in the device.
Selection of electric lamps
Before purchasing light bulbs, you must first choose what devices you need to create proper lighting workplace. If the room is rectangular, then the calculation of the required number of lumens is carried out as follows: you need to multiply the indicators of the illumination norm of the object (determined according to SNiP), the area of \u200b\u200bthe room and the coefficient depending on the height of the ceiling of the room.
Having calculated value, you can divide it by the number of fixtures and get the parameters for the number of light bulbs that you need to purchase.
However, if you need to purchase a standalone lighting fixture, for example, a flashlight, then you do not need to chase very powerful devices, because the brighter the light beam, the greater the power consumption of the source.
Thus, properly selected lamps will allow any specialist to maintain their ability to work for a long time, quickly and efficiently perform their work.
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