With the continuous maturity of LED technology and the continuous reduction of cost, LED spotlights have been widely used in various places. However, the development and popularization of LED spotlights still face many problems. How to develop cost-effective LED spotlights, how to solve the heat dissipation problem of high-power, high-light flux LED spotlights, how to realize the modularity and interchangeability of LED spotlights, How to fully reflect the long life, high luminous efficiency and controllability of LED, let the people enjoy the rich and colorful lighting, and obtain more affordable, safer and more reliable LED products, and also need the joint efforts of various manufacturers and industry.
Safety certification is becoming more and more perfect. The safety requirements of LED spotlights are mostly based on traditional lighting, and according to their own characteristics, a set of safety certification standards has been formed.
At present, most of the safety requirements related to LED spotlights refer to traditional lighting, and according to the characteristics of LED lights, a set of safety certification standards has been formed. At present, in the certification of LED spotlights, the international standards mainly include European CE and North American UL certification, and voluntary certification (CQC) is available in China.
The CE certification includes both LVD and EMC aspects, of which LVD is implemented in accordance with EN60968 (which will upgrade IEC62560); EMC is implemented in accordance with EN55015, EN61547, EN61000-3-2 and EN61000-3-3. In addition, LED lights usually require additional reference to IEC62471 for photobiosafety testing. In North America, UL safety and FCC EMC certification are usually required. UL implementation standards are UL1993, UL8750 and UL1310; FCC implementation standards are FCCPART15SubpartB. In China, the use of voluntary certification (CQC) for LED spotlights, the implementation standards are GB24906-2010 (safety) and GB17743-2007 (electromagnetic compatibility).
In addition, there are many standard regulations on the performance of LED spotlights. The United States has Energy Star (ENERGYSTAR), China has energy-saving certification requirements (executive standard is CQC3129-2010), these requirements are for LED spotlight color temperature, color rendering index, initial luminous flux, luminous efficacy, lumen maintenance, life, Central light intensity, nominal power, power factor, product identification, etc. are specified.
The lifespan of many electronic products is judged by damage, but LED is a long-life light source that will not be broken for a long time. Since the output of the luminous flux decays with time, the industry typically uses the time required for the light to decay to 70 to define the lifetime of the LED source, L70. With the advancement of technology, the light decay of LEDs is getting slower and slower, and it is difficult to fully test the time when the light decays to 70. Since the lifespan of electronic products is exponential, LEDs usually undergo aging for a short period of time, by sampling the light decay data, and then estimating the time of light decay to 70 by an exponential function.
Generally, the luminescence maintenance rate LM (LumenMaintains) is 6,000 hours for LED aging. According to the exponential law, if LM91.8 is 6000 hours later, it can claim 25000 hours of life. If LM94.1 can claim 35000 hours of life, the life expectancy is calculated. The time does not exceed 6 times the test time.
The interface needs to be standardized. According to the characteristics of the LED, a new set of LED spotlight specification interface standards should be developed to realize the modularization and interchangeability of the LED.
At present, LED spotlights are mainly used to replace traditional tungsten halogen lamp, which is limited by its shape, lamp head and installation requirements, which makes the design of LED spotlights face many difficulties. In the standard size range of existing spotlights, it is difficult to achieve high power and high luminous flux of LED spotlights, and at the same time, there are many difficulties in light distribution, heat dissipation, electrical safety, etc., which cannot reflect the long life and high luminous efficiency of LEDs. Features are not conducive to the healthy development of LED lighting.
LED is a new type of light source, LED spotlight is one of the earliest applications that can reflect the characteristics of LED. According to the characteristics of LED, a new type of LED spotlight specification interface standard should be developed. The external dimensions of LED spotlights, module components, parameter bins, standard interfaces, etc. are specified to achieve modularization and interchangeability of LEDs, thereby promoting the healthy development of LED lighting.
At present, the international ZHAGA alliance attracts hundreds of manufacturers, industry and related companies from the United States, Asia and Europe, and has developed specifications for the specification of LED lamps. It is committed to strengthening the compatibility of LED modules and their controls in terms of machinery, testing, parameters, etc. Relevant technical specifications have been published, and some have been revised several times. In China, Jiuzhou Optoelectronics, which is led by the National Semiconductor Lighting Engineering R&D and Industry Alliance, is also actively carrying out related work.
The color temperature of the indoor lighting source that can be used for different purposes can be divided into three groups. Warm, intermediate and cool colors are suitable for different places.
According to "GB50034-2004 Architectural Lighting Design Standard", the color temperature of indoor lighting source can be divided into 3 groups, less than 3300K for warm color, suitable for rooms, bedrooms, wards, bars, restaurants; 3300K ~ 5300K for intermediate colors, suitable for office, Classroom, reading room, consultation room, inspection room, machining workshop, instrument assembly; more than 5300K for cool color, suitable for hot processing workshops, high illumination places.
In "GB50034-2004 Architectural Lighting Design Standards", the color rendering index (Ra) of the illumination source should not be less than 80 in a room or place where it is used for a long time or stay. In industrial buildings where the installation height of the luminaire is greater than 6 meters, Ra can be less than 80, but must be able to distinguish the safety color.
When purchasing LED spotlights, you need to read the instructions or package instructions provided by the manufacturer to determine the power supply voltage and product related parameters, including luminous flux, color temperature, power, color rendering index, and angle. In indoor lighting, when purchasing LED spotlights, it is first necessary to determine whether to use direct power supply from the mains or power supply after transformer conversion, in order to choose whether to purchase MR16 or other spotlights; secondly, to determine the head of the spotlight and The size of the light is required; the angle range of the required spotlights needs to be confirmed again; finally, according to the above requirements of GB50034-2004 Architectural Lighting Design Standards, the color temperature and color rendering index can be confirmed according to the use occasions in order to achieve the desired lighting effect. If you don't understand the parameters of the luminaire, you can check the equivalent mark on the package and see how much power is equivalent to the traditional luminaire.
Due to the uneven LED spotlight technology of various manufacturers, many manufacturers do not completely refer to IEC60630 to design the spotlight shape in order to solve the problem of heat dissipation and power supply space. Spotlights are sometimes used as light sources for some luminaires, so it is important to know if the LED spotlights can fit into the luminaire. If it can't be loaded, you need to purchase a matching lamp housing for a one-piece replacement. For the MR16 spotlight, since there is an electronic transformer or power frequency transformer at the front end, it is necessary to confirm whether it can be compatible with the transformer when purchasing the MR16. If it is not compatible, the light will flash or not. For thyristor dimming spotlights, you also need to consider the compatibility of the luminaire and the dimmer, otherwise there will be flashing or dimming when dimming.
The structure of the lamps and lanterns contends that the current LED spotlights are self-ballasted, that is, the LED drive power sources are all built in the inside of the lamp body, and can be used directly after being powered. LED spotlights are mainly composed of optical components (lenses, reflectors), LED light sources, heat sinks, drive power supplies, and lamp caps. However, the LED spotlights of various manufacturers have different design and processing of the spotlights due to the different materials, processes and LED packaging methods.
LED light source and optical device The current LED spotlight is mainly made of multiple high-power LEDs and integrated package LEDs. With multiple high-power LEDs, a single board is usually required to electrically connect the LEDs. Most of the boards are made of aluminum substrate (MCPCB), and some of them are also made of glass fiber board (FR-4), but they need to be specially designed for heat dissipation pads, and then fixed on the lamp housing by screws or glue. . A plurality of high-power LED spotlights, which are usually combined with each LED to form a spot lens.
Spotlights made with integrated package LEDs do not require a circuit board. They can be directly connected to the LED output of the drive power output line, and are also fixed to the lamp housing heat sink by screws or glue. The secondary optics of this kind of spotlight usually use a lens or a reflector to distribute light. The height of the lens and the reflector are high, and the light distribution at a small angle is difficult.
In addition, for the spotlights with large illuminating surfaces, the secondary light distribution design of the entire luminaire is mostly completed by using a plurality of optical device combinations.
LED Drivers The current LED spotlights are mostly self-ballasted spotlights with built-in power supplies. The built-in LED driver is mainly realized by switching power supply, which is divided into isolated and non-isolated. The primary and secondary of the isolated power supply form an electrical isolation. In the design of the spotlight, it is only necessary to fully protect the primary part of the power supply from the outer casing or other parts of the human body, and the secondary is usually a safe voltage. Simple protection is all right. This type of power supply is relatively safe and reliable, but requires a large space for placement and low conversion efficiency. Since the non-isolated power supply is not electrically isolated between the primary and secondary, it is necessary to make stricter protection isolation on the structure, but the power supply of this type is high in efficiency and small in size. In addition to switching power supplies, there are a variety of other LED driving methods, but the safety and reliability are low, and more efforts are needed in structural design to meet relevant safety requirements. In addition, due to the built-in power supply, the temperature of the components is usually high, which will directly affect the service life and stability of the LED spotlights. Therefore, many manufacturers use glue filling methods to improve the heat dissipation capability of the power supply and improve the insulation between the power supply and the heat dissipation housing.
Due to the controllability of LEDs, various manufacturers have developed dimmable LED spotlights. The existing main dimming methods are thyristor dimming, PWM dimming, 0~10V dimming, DALI dimming, DMX51 dimming, power carrier dimming, etc., all by controlling the driving current or voltage of the LED. Change the brightness of the LED.
The lamp housing heat sink lamp housing heat sink is the first place to consider the design capabilities of various manufacturers. Most manufacturers' radiators are made of aluminum, and the processing technology is organic processing and mold forming. In terms of structural design, in order to increase the heat dissipation capability of the spotlight, each manufacturer usually adopts a fin method.
In addition, the lamp housing portion is also made of a thermally conductive plastic or ceramic material, and is formed by a mold. These two materials have good insulation properties, which enable the product to have high electrical safety performance and facilitate the safe isolation of internal LED drivers. However, these two materials have low thermal conductivity, which is not conducive to heat conduction, and can be used for indoor products that do not require high heat transfer. In addition, the plastic material has the characteristics of light weight, which can greatly reduce the weight of the LED spotlight.
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