Clarify the essence of LED lamps and LED light sources

First, the definition of LED light source and LED lamps

1, the definition of LED light source

LED light source; a component provided by an LED lamp or LED module.

LED lamp: A light source with a lamp head that combines one or more LED modules. The LED module cannot be removed unless permanently damaged.

Note 1: LED lights can be integrated (also known as "self-ballasting"), semi-integrated (also known as "half-ballasted") or non-integrated (also known as non-ballasted), as shown in Figure 1.

Note 2: Includes single or double ended caps in accordance with IEC 60061-1 "Control gauges for interchangeability and safety of lamp caps and sockets Part 1: Lamp caps".

Note 3: LED lights are usually designed to be replaced by end users or ordinary people.

Figure 1 Diagram of the type of LED light

2, the definition of LED lamps

LED luminaire; luminaire designed to use LED light sources.

A luminaire is defined as an appliance that distributes, reveals, or transforms one or more lamps, and includes all components necessary to support, secure, and protect the lamp (but not the lamp itself), and the necessary circuitry. Auxiliary devices and devices that connect them to the power supply.” The definition also includes a note that “an illuminator with an integral non-replaceable light source is considered a luminaire, but the monolithic source and integral self-ballasted lamp are not tested. ."

Second, the reason for misunderstanding LED LEDs as LED light sources

Light sources in traditional luminaires are almost always replaceable. With the advent of LEDs, most of the luminaires using LED modules appear in an irreplaceable form, which seems to be an integrated trend. The boundaries between LED light sources and LED luminaires seem to be unclear. The whole is an illuminator, which can be regarded as a light source. It is clearly stated in the "Note" in the definition of the luminaire: an illuminator with an integral non-replaceable light source is regarded as a luminaire, and a luminaire using an LED module is exactly a luminaire. example.

Third, the light source has the characteristics of being used by different lamps

The light source is used by the luminaire. If the light source is like a source water, the light fixture is like a spring water. LED light sources can be used both in downlights and in road lights. If "LED street light" or "LED tunnel light" is understood as "light source", it cannot be reused by other lamps, which is contrary to the concept of "light source" using "lighting".

Fourth, the difference in the degree of protection of the enclosure

As a light source, there is no special enclosure protection rating or IP20. However, the enclosure rating of indoor luminaires should be at least IP20, and the enclosure protection rating of LED road luminaires should be at least IPX3. The enclosure protection rating of tunnel luminaires should be at least IPX5.

Five, LED light source efficacy is not equivalent to LED lamp performance

As far as the light source is concerned, light efficiency is a classic indicator project. The appearance of each new light source is directly related to the higher light efficiency achieved. Thus, the light effect has become an important indicator of the performance of the LED light source without exception. . Of course, other performance indicators of the light source include color rendering index, chromaticity coordinates, color temperature and lifetime.

For lamps using traditional light sources, the light output of the luminaire, ie the ability of the luminaire to convert the luminous flux of the luminaire, is a classic indicator of luminaire performance. Since the performance parameters of LED light sources have not yet reached the standardization level, and the LED light sources used in many lamps are not replaceable, the concept of light effects has also been misused to LED lighting products.

1, LED light source efficacy and LED lighting efficiency concept

The luminous efficacy of a source is defined as the ratio of the luminous flux emitted by a light source to the electrical power consumed by itself. The unit is lm/W. It does not contain the loss of electrical accessories.

The luminaire efficacy definition is the ratio of the initial total luminous flux emitted by the luminaire to the power consumed by the luminaire under the claimed conditions of use, in lm/W. It is the loss of electrical accessories.

"Light efficiency" is used to evaluate LED light source. "Efficacy" is used to evaluate LED lamps. LED light source efficacy and LED lamp efficiency all indicate the efficiency of converting electrical energy into light energy. It is an index item describing the energy-saving characteristics of lighting products, but its connotation It is different.

2, different luminous flux

The luminous flux of the light source in the light source of the LED light source refers to the luminous flux emitted by the bare light source (the state when it is not yet installed in the luminaire). The LED light source may be an integrated LED lamp or an integrated LED module, a semi-integrated LED lamp or a semi-integrated LED module or a non-integrated LED lamp or a non-integrated LED module.

The numerator in the performance statement of the LED luminaire----the luminous flux refers to the luminous flux emitted by the luminaire after the light source is installed in the luminaire and the power of the required LED control device or LED control device is used at the same time. The power supply of the LED control device or the LED control device may be integral, built-in or stand-alone. A luminaire using an LED source may use a reflector, diffuser or lens.

The light source installed in the luminaire may be a single light source or a collection of multiple light sources, but due to the efficiency loss caused by the interaction of thermal energy and electrical energy, and the efficiency of the optical system of the luminaire, the luminous flux of the LED luminaire is not equal to the luminous flux of the LED light source or its simple accumulation. .

The luminous flux in the efficacy of the LED source is different from the measurement of the luminous flux in the efficacy of the luminaire. The former is measured in the pulse state and the latter is measured in the steady state operating state.

The light in the light effect of the LED light source is not directional, as long as the light energy is emitted, it is recognized in all directions. The light in the efficacy of LED luminaires is directional, and light needs to be sent to useful areas.

In the case of using the same LED light source, the luminous flux of the LED luminaire is smaller than the luminous flux of the LED light source.

3, different input power

The denominator in the LED light source efficacy table and the denominator in the performance of the LED lamp are also different. For example, for a non-integrated LED module, the electric power consumed by the LED light source refers only to the power consumed by the LED module, and does not include the power consumed by the LED control device. The electric power consumed in the performance of an LED luminaire refers to the input power of the luminaire, including not only the LED light source, but also the power consumed by the LED control device. The electric power consumed by the LED luminaire is greater than the electric power consumed by the LED light source.

4, the relationship between the efficacy of LED lamps and the light efficiency of LED light source

Due to the different range of luminous flux and electric power involved, the light effect of the LED light source is different from that of the LED light fixture, and the light source light effect is much larger than the light fixture performance. One is that after the LED enters the luminaire, the junction temperature rises and the light output decreases (heat loss); the second is the system loss that the light source enters the luminaire and uses the LED control device or its power supply; the third is the light passing through the luminaire optical system. The loss after the luminaire efficiency (light loss).

Lamp efficacy = light source efficiency × (1 - heat loss of luminous flux after entering the lamp) × (1 - loss of electrical accessory system) × (1 - light loss after entering the optical system of the lamp) (%)

It can be seen from the above analysis that the light source efficacy is completely different from the luminaire performance and cannot be confused.

1, indoor lighting

For LED downlights, LED flat panel lamps, etc. for indoor general lighting, the classic performance requirements are as follows:

a) Photometric performance

- height ratio

The luminaire height ratio is a project that characterizes the light distribution characteristics of the luminaire. The luminaires with different height ratios are used in different lighting occasions, and the appropriate height-to-height ratio is selected according to the height of the indoor facilities and the illuminance of the luminaires, so as to obtain uniform illumination in a larger range. The aspect ratio is designed to match the lighting design needs while controlling the energy consumption per unit area (LPD) (the waste of energy). For indoor spaces of a given height, the higher the ratio of height to height, the greater the installation spacing of the luminaires, and the fewer the number of luminaires installed in a given space.

- initial luminous flux, luminous flux maintenance rate

- luminaire performance

b) glare control

LED downlight: protection angle, brightness limit (VDT working environment, non-VDT working environment).

LED panel luminaire: brightness limit (VDT working environment, non-VDT working environment), brightness uniformity.

c) Chroma

Color rendering index, correlated color temperature, color difference of different lamps, spatial chromaticity inconsistency, color maintenance.

2, outdoor lighting

For road lighting, the classic performance requirements are as follows:

1) Photometric performance

a) light output

The light output is the luminous flux. The luminous flux of the LED is studied to analyze the current light output capability of the LED lamp, and the road conditions applicable to the light output value of the LED street lamp are predicted according to the lighting requirements specified by the national standard for road lighting. Motor vehicle roads in cities are divided into express roads or trunk roads, secondary trunk roads and branch roads. The luminous flux emitted by the street light is the basic condition for ensuring that the road surface meets the illumination level required by the road lighting standard.

b) Longitudinal light distribution (short projection light distribution, medium projection light distribution, long projection light distribution)

The longitudinal light distribution is classified according to the projection angle of the maximum light intensity. The length of the road surface that can be illuminated is different for the street lamps with different longitudinal projection angles. If the light is projected at a small angle along the longitudinal direction of the road, the length of the illuminated road surface is compared. short.

When the longitudinal angle of light projection along the road increases, the distance between the poles increases, and the lamp power (LPD value) per unit road area decreases accordingly. The far or near projection of the beam is one of the important factors for the energy saving level of the street lamp.

c) Transverse light distribution (Class I, Class I-4, Class II, Class II-4, Class III, Class IV)

Applicable horizontal light distribution type street lamps should be used according to the number of lanes. If the correct application of a type II horizontal light distribution streetlight is 4 lanes, then if the wrong one is used for 2 lanes, there will be a large proportion of luminous flux. When the area is irradiated outside the road, the utilization of luminous flux is lowered, and the LPD value is affected.

Figure 2 is a schematic illustration of various light distribution luminaires for a roadway, and Figure 3 is a legend of a class III-middle projection luminaire in a half space and on a road.

Figure 2 Front view of the roadway with different types of lamps

Figure 3 is a class III - medium projection luminaire in the hemisphere and on the road

d) Light distribution at C-90° and C-270°

Describe the longitudinal extension characteristics of the road to adapt to the different lighting needs of the roadside area and the roof area, to meet the requirements that the road is illuminated and the roof next to the road boundary line is also properly illuminated, embodied in the environment of road lighting standards. Than the SR value.

The roadside requires more luminous flux and less space on the side of the house. Therefore, in addition to satisfying the above photometric characteristics, the streetlight should also reasonably distribute the luminous flux of the roadside and the side of the house, and photometrically appear as the roadside and the side of the utilization coefficient curve. Luminous flux. The measured light distribution curve of C-90° plane and C-270° in the light distribution diagram of the luminaire cannot be simply processed into a symmetrical form. Otherwise, the luminous flux distribution of the luminaire will be unreasonable, and the utilization coefficient will not reduce the illumination efficiency of the luminaire.

e) beam uniformity (γ angle of maximum light intensity, ratio of light intensity to maximum light intensity in the range of 25o near the lower point of the lamp / )

- When the light is unevenly illuminated, the road surface will appear bright and dark. The lack of contrast between the obstacle and the road surface will make the driver's ability to observe obstacles on the road surface less, and the moving objects on and around the road will not be seen.

To obtain a uniform illumination effect on the road surface, the projection angle of the maximum light intensity in the beam is very important, and the light intensity below the street lamp should be the smallest. As the elevation angle γ increases, the light intensity I' at the gamma angle should increase, and Satisfactory functional relationship, when the light intensity is close to this functional relationship, the road surface can obtain a uniform illumination effect. When the projection angle of the maximum light intensity in the vertical plane reaches 55o-65o, the uniformity of illumination can be achieved.

Compared with road illumination, road surface brightness uniformity can have a more objective impact on driver observations. The brightness of the road surface is related to the observation angle. It is also related to the pavement material. When the projection angle of the maximum light intensity in the vertical plane reaches 65o-75o, the brightness uniformity of the road surface can reach a relatively high level.

- The ratio of the light intensity to the maximum light intensity in the range of 25o near the lower point of the lamp / another important condition of the beam uniformity is that the light intensity at the lower point of the lamp should be the smallest, and as the angle increases, the light intensity should gradually increase. Big. The ratio of the light intensity to the maximum light intensity in the range of 25o near the lower point of the lamp is one of the important parameters for evaluating the uniformity of the light distribution of the street lamp. / ≤ 0.35 is one of the important conditions for street light distribution to meet the uniformity of road illumination. When the ratio is greater than 0.35, it will produce a light under the lamp and a dark spot unevenness between the poles.

f) cut-off level (80°-90° ring light, 80°-90° light)

The brightness of the light source of the LED street lamp can reach tens of millions of cd/m2, and the illumination direction of the light is not well controlled, which will cause the driver to feel glare and easily cause visual fatigue. When the degree of glare is strong, it will affect the driver's observation of the road. The glare is generated by the light that the street light directly enters the eye. In order to improve the adverse effects of glare on vision, road lighting fixtures are required to have cut-off control measures. From the observation position and the observation direction of the driver, the light output of 80°-90° on each C plane of the street lamp directly enters the eye to cause glare.

Controlling the band-pass of 80°-90°--- limiting the light intensity of 80°-90° is an important way to control the glare of street lamps.

g) Luminous energy efficiency

2) Chroma

The relevant color temperature requirements for LED road lighting should be noted, and the color temperature should be controlled below 4100K.

3. Lumen maintenance rate should not be a mandatory test for LED lamps

At present, some technical specifications or standards for LED lamps and LED light sources have the same life test requirements for LED light sources and LED lamps, that is, tests for lumen maintenance rate, from 1000h, 3000h, 6000h to 10000h.

Lumen maintenance is an indicator of the lifetime of a light source. The meaning is the ratio of the luminous flux value at a given time during its lifetime to its initial luminous flux, expressed as a percentage x of the initial luminous flux. For example, 70% lumen maintenance is the luminous flux as the initial luminous flux. 70%.

Unlike conventional light sources, current LED light sources have not been standardized, and most LED arrays or LED modules consisting of various types of package specifications do not provide relevant parameters such as lumen maintenance related to the claimed life of the product. Since the light source does not provide data, a large amount of lumen maintenance test has to be performed using LED lamps.

Depending on the characteristics of the LED, it is generally considered that the LED module has reached the end of its life when it no longer provides a percentage of the claimed initial luminous flux. Therefore, the lifetime of an LED module generally refers to the length of time that the LED light source provides a percentage x of the claimed initial luminous flux under standard conditions, generally given in the form of a combination of lifetime and failure rate Fy when lumens are maintained at Lx. For example, the life and failure rate F50 at L70.

The form of LED light sources currently used in LED luminaires typically includes LED packages, LED arrays, LED modules, and LED lights. In addition to luminaires that use LED lights, life is often an important parameter in describing the performance of LED luminaires.

Usually, the LED module claims that the L70 life is more than 25000h. Although the extrapolation method can be used, the corresponding lumen maintenance test time can be reduced, but the verification test time of the general lumen maintenance rate is also above 6000h. This is also the reason why LED lamps are currently undergoing long-term lumen maintenance tests.

Different combinations of the same LED modules can produce different lighting products. If lumen maintenance tests are performed on each end product, a large number of repeated tests are performed, which consumes a large amount of time and cost.

The solution to avoid the large life test of LED luminaires is the lumen maintenance data of the modules provided by the LED module manufacturers, thus verifying the lumen maintenance level of the LED luminaires.

IEC/PAS 62722-2-1:2012 "General Requirements for Performance of LED Lamps" stipulates that when the LED module complies with IEC/PAS 62717 "Performance Requirements for LED Modules for General Lighting", the lumen maintenance test of LED lamps may not be performed. At present, the Lighting Industry Standardization Committee has begun to convert these two standards into the work of China's national standards.

The application of LED in lamps and lanterns has changed the current LED lamps for long-term lumen maintenance test from LED street lamps, LED tunnel lamps, LED downlights and LED panel lamps. It should be vigorously corrected that LED modules do not perform lumen maintenance test, but The current state of inversion of LED luminaires is calling for LED module manufacturers to conduct lumen maintenance tests on their products.

Seven, the conclusion

1, the classic performance requirements of LED lamps should be comprehensively assessed, should not be neglected.

General lighting indoor LED lamps, distance ratio, protection angle and / or brightness limit are the main performance indicators, should not be missed.

LED road lighting fixtures should meet the road lighting standard values (road surface brightness and brightness uniformity, road surface illumination and uniformity, threshold increment, environmental ratio) and road lighting energy conservation evaluation value (LPD) as the fundamental starting point, LED road The lighting fixture standard must explicitly introduce the requirements of these lighting standard values, and become the requirement for LED road lighting fixtures. Under the premise of satisfying LPD, the actual response can also be above the aspect ratio. The level of interception, the distribution of longitudinal light and the distribution of lateral light must be clear.

2, LED lights have the requirements of light distribution, LED light source generally does not have light distribution requirements.

The distance-to-height ratio of general lighting indoor LED lamps is actually designed for lighting.

The vertical light distribution of LED road lighting fixtures involves the installation spacing of the lamps, and the horizontal light distribution involves the number of lanes.

3, LED lamp performance is based on the premise that LED lamps meet the classic performance requirements.

LED light efficiency as a light source index project is relatively simple, but LED lamp performance is one of many performance requirements, subject to other performance requirements, various performance indicators should be coordinated, can not one-sided pursuit of LED lamp performance an indicator, no It should be based on the assumption of the comfort and reliability of the lighting environment.

references

[1] Clarify the efficacy of LED light source and the efficacy of LED lamps, Chen Chaozhong, Shi Xiaohong, Yang Wei, Li Weijun, China Lighting Appliances, No. 12, 2011

[2] Interpretation of the common standard "LED flat panel lamps for indoor general lighting", Chen Chaozhong, Shi Xiaohong, Yang Wei, Wang Wei, Li Weijun

[3] Definition of LED lamps and LED light sources, Shi Xiaohong, Chen Chaozhong, Li Weijun, Wang Wei

[4] Analysis of the current situation of luminosity data of LED road lighting fixtures, Wang Wei, Chen Chaozhong, Shi Xiaohong, Journal of Lighting Engineering, Vol.20, No.3, No.3

[5] GB/T XXXXX-201X "LED Downlight Performance Requirements" (Approved)

[6] US Department of Energy Supplementary Requirements for Class A Lamps Meeting ENERGY STAR Requirements (2008.8), Supplements (2009) No. 002, Light Sources and Lighting

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Edit: Nizi