Shi Kexiao, a professor-level senior engineer at the China-Guangzhou International Institute of Architectural Design and Research, has converted 11W electric power into efficient lighting for light energy. As the name suggests, it is clear. There must be a light source for illumination. The light source we see every day can be divided into two categories: artificial light source and non-artificial light source.
Among the artificial light sources, the most used one is an electric light source. As a lighting designer, it is necessary to understand the basic characteristics of some light sources and how to use their characteristics reasonably, and to become a compulsory course for lighting designers. At present, the new design specifications are being revised, and the lighting requirements for lighting places are more complete and specific. In this case, many lighting designers require further in-depth and comprehensive understanding of the performance characteristics of the light source in order to more rationally select the light source in the project.
First, several common parameters of the electric light source 1. The luminous efficiency of the light source The efficiency of the electric energy into light energy, how much light can be converted into 1W, let us first understand the electromagnetic spectrum. The so-called "spectrum" is arranged in a curve or a relatively neat manner according to the category of the object. For example, genealogy is arranged by generation and blood relationship; recipes are arranged by type. We must talk to people who have a good voice, and who do not speak well, others are not willing to deal with you.
The electromagnetic spectrum is a large family, divided by wavelength or frequency, and the wavelengths from 1015m to 108m are members of this family. The wavelengths range from short to long are cosmic rays, ray rays, X-rays, ultraviolet rays, visible light, infrared rays, radar, television, broadcasting, and power transmission. The wavelength range of visible light is 380780 nm. nm (nanometer) is the unit of length, and 1 nm is equal to one billionth of a meter.
It can be seen that visible light is a small segment in the electromagnetic spectrum.
We can see the same "clear" at every wavelength, no. The research shows that the human eye sees the most "clear" to the yellow-green light of 555nm. The 1W electric power is completely changed to 5 55nm yellow-green light is 683lm. For other wavelengths of light, we seem to have to "discount". The "discount" is different for different wavelengths (see Table 1).
Turn the numbers in the table into curves (see), which has a proper noun called "Spectral Light Efficiency of the Human Eye." In fact, the spectral light efficiency of the human eye is further divided into "light vision spectral light efficiency" and "dark vision spectral light efficiency", which is not mentioned here.
When a light source converts electrical energy into light energy, even if all of the light energy falls within the wavelength range of visible light, we cannot all "see" but "discount". Because of this, the light source does not use a percentage to express efficiency when electrical energy is converted into light energy, but is expressed by how much lumen light is converted per W electric power. The lumen number of light is the power of the part of the light that is perceived by us.
People can distinguish colors when they are very young, but it is not easy to say the color accurately. There are many ways to express colors, such as: using words; using words to add numbers; using chroma diagrams. If it is expressed in words, it is not enough to fully express the characteristics of the color; if it is described by the chromaticity diagram, it is too complicated and not easy to understand. In practice, we often use the "color rendering index" and "color temperature" to express the color of the light source. Although the color is not very accurate with these two parameters, it can express the color characteristics of the light source more simply and accurately.
In order to clarify the two parameters of the "color rendering index" and "color temperature" of the light source, we must first introduce the concept of object color.
What is the object color? Many people think this is a strange problem. Children know red orange, yellow, green, blue and purple. However, to clarify the nature of the object color, to say which color is related to the factors, not everyone knows.
In daily life, many people regard the color of an object as an inherent characteristic of the object itself. If the carbon paper is blue, the cloth is red, the paper is white, and so on. In fact, from the perspective of colorimetry, the color of an object depends on the reflection characteristics of the object itself and the spectral distribution characteristics of the light source that illuminates it. The color of the object we usually say refers to its color in daylight. We see the red cloth because it only reflects the red spectrum in daylight, and absorbs other spectral components. The carbon paper is blue because it reflects only the blue spectrum in sunlight and absorbs other spectral components. The paper is white because it has the same reflection on all spectral components in daylight. If the blue carbon paper is illuminated with a red light source, then it can reflect the blue component light source. Instead, it absorbs all the red light components. At this time, the carbon paper we see is "black".
By the same token, if you use red light to illuminate the red cloth, it is also "black"; when you use blue light to illuminate the white paper, the white paper will become "blue" and the white paper will be illuminated with red light, and the white paper will become "red". .
As mentioned above, the color of an object in everyday life refers to its color in daylight. Therefore, daylight is the standard light source in our lives. In terms of colorimetry, it has the best color rendering properties. The International Commission on Illumination sets the color rendering index of daylight to 100 (please note that it is not 100%). The color rendering index of other light sources is based on daylight. If the spectral composition and energy distribution of a light source are exactly the same as daylight, the light source The color rendering index is also 100. However, there is no such thing as an electric light source with a color rendering index of 100. The halogen halogen lamp closest to daylight, its color rendering refers to how the color rendering index is determined, the International Commission on Illumination When defining the color rendering index, the wavelength of 380780 nm occupied by visible light is divided into 8 segments according to the wavelength, and then 8 kinds of object colors representing 8 bands are respectively selected (see). The eight object colors are respectively illuminated by daylight and the light source to be measured to find the color difference between them, and then the color rendering indexes of the eight object color rendering indexes to be measured are obtained, which are respectively represented by RPR2.
Called a special color rendering index. The average value of RiRs is called the comprehensive color rendering index or the general color rendering index and is expressed by Ra. The color rendering index we usually say refers to the comprehensive color rendering index.
The color rendering index is only a parameter of the color of the light source. Sometimes, the two light sources with the same color rendering index may not have the same color. For example, the special color rendering index of the first light source is Rt=20, and R2R8 is 100. At this time, the integrated color rendering index Ra=90; the special color rendering index RtR7 of the second light source is 100, and 68=20 At this time, its comprehensive color rendering index is also 90. Obviously, the first light source lacks violet light, while the second light source lacks red light, and their color rendering index is the same. This shows that under certain conditions, the color rendering index does not fully accurately indicate the color of the light source. At this time, the color rendering index of the light source and the "color temperature" value of the light source should be "bundled" together to accurately describe the color of the light source.
In order to clarify the concept of the color temperature of the light source, we look at an example of life. If you ask a person, "How far is the home from the work unit, does it mean distance? Yes, the speed of the average person riding a bicycle is about 15km/h. It can be known that this person lives about 78km away from the unit. Originally, time The distance does not matter, but the "speed" starts with the absolute temperature to indicate the color of the light source. Here, the "black body" is the "intermediary". This is because the color of the black body has a unique correspondence with the temperature. Health - a color, and the color of the black body only corresponds to its temperature.
The color temperature of the light source is defined as follows: If the color of a light source is the same as the color of a black body at a certain temperature, the temperature of the black body is called one of the methods we represent the color of the light source, that is, the temperature is used to indicate the color of the light source. That is, the color temperature of the light source in black body is referred to as the color temperature. In fact, the color represented by the black body temperature should be called the temperature color. The term "warm color" is more reasonable and easier to understand. The principle and spectral characteristics of the gas discharge lamp are different from those of the heat radiation source. Therefore, the gas discharge lamp is called the correlated color temperature, also referred to as the color temperature.
After clearing the concept of color temperature, three points should be noted: First, the color temperature indicates the color of the light source. For example, the color temperature of the sun at sunrise is about 1800K, and its color is dark red. At noon on a sunny day, the color temperature of the sun is 5600K. It is white; the color temperature of ordinary fluorescent lamps is about 6000K, and the color is blue; if the color temperature of the light source is higher, the color of the light source will be purple. The color temperature of the light source is low, indicating that the red light component in the spectrum of the light source is relatively large; the white light indicates that the light of various spectra is substantially equal; the higher the color temperature of the light source, the more blue or purple components in the spectrum of the light source. Second, as for the two light sources as mentioned above, the light source of Rt=20 lacks violet light, and the relative red light is more. The color temperature is lower than the other light source R8=20, indicating that it lacks red light, and the relative purple light is more. Therefore, its color temperature is high. At this time, by bundling the color rendering index and color temperature, you will see the difference between the two light sources. Third, the relationship between the color temperature of the light source and the actual temperature of the light source. For a heat radiation source, the color temperature is high and the filament temperature is high; for a gas discharge lamp, the color temperature and temperature are not necessarily related. If the color temperature of the fluorescent lamp is 6000K, it is not hot to touch, but the color is blue.
The life of a light source is divided into full life and effective life. The so-called full life is the total ignition time of the light source from ignition to the end of life; and the effective life is the cumulative ignition time when the luminous flux of the light source is attenuated to 70% of the initial value. We must pay attention to two points when choosing a light source. One is that the effective life of some light sources is the full life. For example, a tungsten halogen lamp, because of the effect of the tungsten halogen cycle, its light flux decays little at the end of its life. The second is that the lifetime of the light source refers to the average bare spot life, and the consistency of some light sources is better, and some are worse. We should try to choose a consistent light source; in addition, it should be noted that some light sources have a much shorter flash life in the luminaire than the bare point, which depends mainly on the heat dissipation conditions of the luminaire. The parameters of several common light sources are shown in Table 2. Table 2 Parameters of several common light sources Light source Light source (lm/W) Color rendering index Ra Color temperature (K) Incandescent halogen tungsten lamp General fluorescent lamp Three primary color fluorescent lamp Xenon lamp Xenon lamp High pressure sodium lamp Metal halide lamp optional Second, the characteristics of the lamp We usually say that the light source, sometimes only refers to the light source itself, and sometimes contains lamps, such as "fluorescent lamps", usually with lamps. Then, what are the functions and characteristics of the lamp? The main functions of the lamp are three: one is to support the light source, the other is to redistribute the light emitted by the light source, and the third is to beautify the environment.
The redistribution of light energy by the luminaire is basically a spherical projection, which is illuminated in all directions, and only a small amount of light is blocked at the lamp holder. However, when the light source is installed in the luminaire, the light will illuminate in a specific direction. The distribution of such light is symmetrical about the axis of the optical axis; some are symmetric with respect to the X and Y axes; others are asymmetric, and this asymmetric distribution often has special uses. This distribution of light to the luminaire is represented by a light distribution curve. The light distribution curve has a wide light distribution type light distribution curve, a narrow light distribution type light distribution curve, a cosine type light distribution curve, a batwing type light distribution curve, and an asymmetric light distribution curve. They have their own uses, but regardless of the light distribution curve, in addition to ensuring the trueness of the curve, the value of the lamp efficiency and the beam angle should also be indicated. For some professional luminaires, the beam angle and the optical field angle at the time of concentrating and astigmatism, as well as the values ​​of beam efficiency and light field efficiency (see) should be indicated separately.
The efficiency of a luminaire refers to the utilization of light energy. That is to say, how much light energy from a light source becomes our useful light energy, usually called effective luminous flux.
Luminaire efficiency is an extremely important indicator.
The unreasonable selection of lamps will cause great waste. If the cost of lighting is increased by 10,000 yuan in the project, the total investment will increase by about 50,000 yuan. This is because, after adding lamps, not only cables and transformers will increase, but also air-conditioning equipment will increase.
III. Illumination Calculation In the engineering design, in order to verify whether the illumination on the work surface meets the requirements of national or industry specifications, in order to meet the various requirements of the application site calculation point, the illumination calculation is required. The following describes several calculation methods.
As we all know, part of the luminous flux emitted by the light source is directly projected onto the working surface, and a part of it is first projected onto the wall or ceiling, and a part of the reflected light falls onto the working surface. This has the problem of how much light flux is emitted by a light source. According to the formula for illuminance calculation, based on years of experience, the utilization factors under various conditions are summarized. The closer these utilization factors are to the actual situation, the more accurate the calculation results. The calculation formula using the coefficient method is as follows: N-one source number Y source luminous flux, lmU one-by-one factor K-one lamp maintenance factor A working surface area, m2 in the design or preliminary design, it is necessary to estimate the lighting power consumption . Because it is an estimate, the accuracy of the calculation results is not high, and the method can be used to obtain the result quickly, so the use is more common. The basic calculation formula is as follows: P0 illuminance is 11x unit capacity, W/m2 application using coefficient method and unit capacity method, in order to facilitate the work of engineering designers, try to improve the accuracy of calculation, related lighting design manual The list gives a variety of coefficients, you can choose according to the actual situation.
In practical applications, some places have high requirements for horizontal illumination, some places have high requirements for vertical illumination, and some places have high requirements for certain components. At this time, the calculation by point-by-point calculation method is required. The basic formula of the point-by-point calculation method is the inverse square law, that is, the luminous intensity of the point is calculated one by one, cd R—the distance between the point and the light source is calculated, m. In practical applications, according to different calculation requirements, each can be derived. A variety of calculation formulas. It is worth noting that the basic condition of the point-by-point calculation method is that the light source must be a point source. When the light-emitting surface of the light source is large and close to the calculation point, that is, when the light source cannot be regarded as a point light source, the light-emitting surface should be divided into many small light-emitting surfaces, and these can be regarded as the formula of the light-emitting surface of the point light source and then the point light source. Calculation.
Since the point-by-point calculation method is complicated and computationally intensive, it is now usually carried out on a computer using related software.
4. Selection of electric light source and luminaire When selecting the light source, it should be operated strictly in accordance with the national and industrial standards, and at the same time, according to the policies and regulations of the state and relevant departments. First of all, we should select those high-efficiency light sources and luminaires. If there is a high requirement for the color of the light source, the high-efficiency light source and luminaire should be considered under the premise of meeting the color and color temperature requirements of the light source. At present, low-power metal halide lamps have been used for a period of time, and their color rendering is good, color temperature is optional, light efficiency is high, and long life is long. It is an ideal light source.
When choosing a luminaire, pay attention to choosing a more reasonable light distribution curve. Some places require a higher level of illumination, some places require a higher vertical illumination, and some places require a higher cylinder illumination. For places that are not demanding, it can be calculated by the coefficient method; for places with higher requirements, it should be calculated by point-by-point calculation.
Night lighting and theme park lighting are increasing in proportion to the overall lighting. The night illumination of the building occupies a prominent position. Attention should be paid to the following aspects of night lighting of buildings: night lighting should cooperate with other majors, especially architectural professions. As far as the lighting profession is concerned, the use of lighting color should have a reasonable connotation; the illumination of the building wall should take into account the ambient illumination; the location of the lighting fixture should be reasonable and concealed. In fact, Beijing has seen a number of night illuminations of buildings with profound cultural connotations and visual effects. It beautifies the night scene of Beijing and is a better night lighting effect.
In short, to do a good job in lighting design, you must have a deep understanding of the characteristics of light sources and lamps. These characteristics of light sources and luminaires are the cornerstone of lighting design. It is these cornerstones that create a variety of lighting works with different moods. ;S
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