First, the difference between led lamp and traditional lamp light source
At present, there are many differences between led lamps and traditional light lamps in terms of performance, evaluation and design.
1. Performance evaluation of LED lamps
A) color space uniformity evaluation to evaluate the color differences of different observation angles of LED lamps.The characteristics of a single luminescent body of traditional light source are different. The LED lamps used by LED lamps are composed of multiple luminescent bodies and emit light. There are color differences among luminescent bodies in LED lamps.
B) evaluate the durability of LED lamps by their service life.The measurement and evaluation of the life performance of traditional light source has been standardized, and has interchangeability, so the life of traditional light source lamps and lanterns can be replaced by damaged light source, and according to the 10 years of life of the lamp control device to meet the requirements, so generally do not evaluate the life of traditional light source lamps and lanterns.
The life of LED lamps is related to the life of the LED itself, the LED driver and the environment provided by the lamps to the LED, etc. At present, there are many LED lamp forms. Except the LED with standard lamp holder, other LED lamps do not have interchangeability.When evaluating the life of LED lamps, it is necessary to claim not only the optical maintenance life (LX), but also the failure rate (FX).
C) the evaluation parameters of the light flux ratio that can be utilized by lamps are different from those of traditional lamps.Traditional lighting is evaluated by lamp efficiency, while LED lamps are evaluated by light efficiency.
D) unlike the traditional lighting source, luminosity can be tested separately. The relative method can be used in luminosity measurement. The led light source is extremely sensitive to temperature, so it is not appropriate to separate the led light source from the lamp for separate measurement.
2. LED lamp designLED lamps in the optical system design, electrical accessories, cooling measures and structure design compared with the traditional light lamps have a significant difference.
A) optical systemThe optical system in lamps and lanterns is the soul of lamps and lanterns.In general, the optical system of traditional light source lamps consists of light source, lamp holder, reflector and pervious cover.Due to the luminosity characteristic of some LED units with 2 luminosity, the luminosity system of lamps is quite different from that of traditional light sources.Specific performance characteristics are as follows:
1) LED lamp optical system is generally an LED array or LED module composed of LED chip and lens. The array is sometimes arranged on a flat aluminum substrate, or on a raised or concave molded substrate.Lighting manufacturers can combine multiple LED units or dozens of LED units on the substrate according to lighting requirements. Attention should be paid to the consistency of light color of LED units after the combination and the uniformity of color space of LED lamps should be assessed.
2) the photoelectric characteristics of LED are very sensitive to the temperature change of PN junction;Packaging resin will rapidly degrade under high temperature and strong light;Long-term radiation will gradually reduce the photoconversion rate of phosphors and lead to color shift.The life evaluation of LED lamps usually evaluates the lumen maintenance rate of LED lamps under the condition of limited color shift.
B) electrical accessoriesLED drive power supply is the key factor of LED lamp performance, and also one of the important elements of lamp selection or design.The electrical design of LED lamps shall take into account the LED characteristics and quantity, the installation location of the lamps, and the position of the lamps in the power grid to consider electrical safety, constant current drive, immunity and EMI, and select or design the appropriate LED driving power supply.Since LED is driven by a low voltage constant current source of 2V ~ 3V, it is not like ordinary incandescent bulb that can be directly connected to 220V ac mains. Therefore, power supply and control circuit must be designed to drive LED.In addition, the electrical connection of led module is also an important part of the electrical system of led lamps. Safety should be fully considered and standard connectors, adequate insulation and anti-shock protection should be adopted.
C) cooling measuresLike traditional light source lamps, LED lamps also generate heat. The heat of LED lamps comes from the loss of LED photoelectric conversion and LED drive power.Unlike the principle of traditional electric light sources (thermal radiation from incandescent lamps and gas discharge from fluorescent lamps, etc.), LED luminescence is electroluminescent. Due to conversion efficiency problems, most of the energy output is mainly converted into heat in the form of non-radiative compound lattice vibration.And heat is transferred in the LED not by radiation but by conduction.In the heat dissipation design of LED lamps, the main goal is to effectively conduct the heat of LED chips and effectively control the LED junction temperature in LED lamps.
For LED lamps, in addition to the LED is a heating part, the driver in the LED lamps is also a heating part, in order to ensure the life of coordination with the LED light source, the thermal control of the LED driver is also very important, if the use of internal drive power supply, lamps should be based on its internal environment temperature to choose the driver marked with the corresponding tc.When the driver is installed independently, the corresponding tc driver should be selected according to the possible ambient temperature at the installation site.
D) mechanical components and structuresThe function of the machine is to determine the position and interrelationship of the optical system, electrical system and thermal system of the lamp through the structural design, so that the lamp can be fixed in the set environment and used safely.
Traditional lamps and lanterns of the mechanical system is controlled by a fixed source, reflector, and light device and other parts of structure, soft rope or cord go line structure, seal structure, the structure of the mechanical protection, fixed structure and lamps and lanterns of lamps and lanterns to adjust parts such as the structure, the concrete by the holder or the light source connector, socket mounting bracket, flexible wire fixed frame, terminal blocks, a hood and a chimney and a mounting bracket of lamps and lanterns, etc.
Due to the characteristics of LED light source, LED light includes package, module, LED light engine, integral LED light, non-integral LED light and other forms. Except the last two forms which may have internal structures similar to traditional light source lamps, other LED lights do not have standard lamp caps. In this case, LED lamps have the following structural characteristics:There is no lamp holder in the LED lamp.
Instead, the electrical connection between the LED lamp and the lamp is completed with a connector, and the LED lamp is fixed to the main part of the lamp in other ways.In order to export the heat generated by LED chips, LED lamps have a large number of heat sinks, and the volume and weight of lamps are much larger than that of traditional light lamps.
The installation structure of lamps should be considered accordingly to ensure the safety and reliability of installation.At the same time, the heat sink should be designed to be easy to clean or not easy to accumulate ash structure, otherwise, the efficiency of the heat sink will quickly reduce.When the LED lamp USES the power cord, and the power cord can be removed for maintenance, it belongs to the non-z-type connection. Like the traditional light source with non-z-type connection, the LED lamp should also use the soft wire fixing frame.