Identification and improvement of application standards for general lighting LEDs and final products

1. Composition of product standard system

LED is a new type of lighting appliance product. LED products include the LED itself, the supporting control devices and the lighting products that use it as the light source. The standard clauses related to these products mainly consist of the following aspects.

1. Terms related to the safety of people’s lives and property during the use of the product

As an electrical product, the safety requirements during use are the most important part recognized internationally. In this regard, my country's product standards are almost equivalent to IEC standards. Even the safety standards formulated by my country itself are basically referenced to IEC standards and/or ANSI standards, and are all promulgated and implemented as mandatory standards. For example, the majority of clauses in the GB19510/IEC61347 lamp control device series and the GB7000/IEC60598 lamp series standards and light source safety standards belong to this category.

2. Performance requirements of LEDs, control devices and lamps themselves

When consumers buy products, they are actually buying the product's functional use, and the product's functional use is achieved through the assessment of performance clauses in this regard. As lighting LED products and corresponding supporting products are no exception, the latest (draft for approval) "Performance Requirements for LED Modules for General Lighting ", "Performance Requirements for Self-ballasted LED Lamps for General Lighting " and "Performance Requirements for DC or AC Electronic Control Devices for LED Modules" standards reflect this requirement in indicators such as light efficiency , color characteristics, light decay, life and energy efficiency, as well as the distributed luminosity and efficiency indicators of lamps.

3. Requirements for the coordination between LEDs, control devices and lamps

This part of the standards can be divided into the following categories according to the product:

(1) Design requirements of light source for control device

The control device of the lamp serves the light source. It should be said that the safety index of the lamp control device is the most important, but most of its assessment requirements are similar to those of other electrical appliances, so it is relatively easy to understand. As for the requirements for coordination with the light source, its internal mechanism is relatively profound. The normal working state of the light source is mainly provided by the control device. The coordination performance of the control device and the light source is directly related to the luminous efficiency, luminous stability and service life of the light source, and affects the overall energy efficiency of the system.

(2) Light source design requirements for lamps

After the light source is installed in the lamp, its working condition depends on the design structure of the lamp. If the design structure of the lamp is unreasonable, it will also seriously affect the normal operation and service life of the light source. For example, the road lamp using LED requires not only good sealing to ensure dust and water resistance, but also good heat dissipation to ensure that the junction temperature of the LED is still at a reasonable level under many unfavorable conditions.

4. Power supply Assessment clauses for lighting appliances when they are working

As an electrical appliance, it must comply with the power supply's assessment requirements to ensure the normal operation of the power supply system and maintain a high power supply efficiency. The assessment clauses in this regard include GB17625.1/IEC61000-3-2 line power factor, power supply current harmonics, and GB17625.2/IEC61000-3-3 voltage drop and flicker.

5. Limit and resist external electromagnetic interference

As an electrical appliance, the electromagnetic interference ( EMI ) to other electrical appliances should be limited , such as the power terminal interference and radiation interference in GB17743/CISPR15. At the same time, it should be able to resist various possible electromagnetic interference (EMS), such as the clauses for resisting various electromagnetic interference in standards such as IEC61547 and FCC.

2. Identification and introduction of application standards for LED lighting and its final products

From the above introduction, we can know that for any product, generally no single standard can fully cover all the assessment requirements. Any product standard is aimed at a certain aspect of the corresponding product and is applicable to a certain range. Generally, multiple standards complement, reference and support each other to form a complete standard system. This is the practice adopted by various standard systems in the world.

1. LED lighting Standards for lamps and final application products

Due to the industry separation left over from China's planned economy and the narrow knowledge of many lighting industry practitioners, we often hear some people say that "there are currently no assessment standards for LED lighting fixtures and final application products." In fact, this statement is very naive. For example, the various final application products that use LED as the light source, the lamps or self-ballasted lamps they form have not changed at all in terms of use functions and product properties, so the current standards and requirements for lamps almost cover their assessment content. The various lamps currently produced using LED light sources must meet the corresponding safety standards, electromagnetic compatibility requirements and light distribution requirements of such lamps. In addition, the assessment standards for the on-site lighting effects of such lamps are also completely suitable for such lamps. In other words, the assessment requirements for lamp products (also the terminal products of the application) that use LED as the light source have long existed. It's just that many practitioners in our industry have not yet recognized them.

2. LED control device product standards

In terms of LED control devices, the international community had already met the IEC61347-2-13 safety standard requirements and IC E62384 performance requirements two years ago, and the corresponding national standards in China have been submitted for approval this year. These two standards and the referenced GB19510.1/IEC61347-1 standard and China's corresponding EMC standards have formed a complete assessment requirement for lighting LED control devices. In addition, in the GB/TXXXX/ICE62384 LED module control device performance requirements standard (submission draft), the requirements for LED control device energy efficiency assessment have been added. The implementation of these standards can effectively control the current low energy efficiency and unsafe hidden dangers of the current limiting of LED current, which often uses resistors. Even for some control devices that do not limit or stabilize the current of LEDs, but only have the function of adjusting the dimming, color change, and light and dark alternation of each group of LEDs, there is already an assessment standard of GB19510.12/IEC61347-2-11 "Special Requirements for Miscellaneous Electronic Circuits Used with Lamps". It should be said that the existing and upcoming assessment standards for lighting LED and module control devices are already very complete.

3. Standards for lighting LEDs and their modules

Regarding lighting LEDs and their modules, product standards in this area are new and need to be continuously enriched and improved. This year, my country has formulated the "Safety Requirements for Self-ballasted LED Lamps Over 50V for General Lighting" and the "Performance Requirements for Self-ballasted LED Lamps for General Lighting". Because this product has the characteristics of independent use and less correlation with other supporting products, its standards are relatively complete. Coupled with the applicable EMC assessment standards, it has basically become a complete assessment system.

For lighting LEDs and their LED modules, five standards were formulated this year, namely, "Terms and Definitions of LEDs and LED Modules for General Lighting", " Test Methods for LED Modules for General Lighting", "Safety Requirements for LED Modules for General Lighting", "Performance Requirements for LED Modules for General Lighting", and the industry standard "Performance Requirements for Light Emitting Diodes for General Lighting" (which has become a draft for approval). These five standards formulated this year have largely improved the assessment requirements for this type of finished products. It should be said that when these lighting LED standards reported this year were promulgated, China's standard system for lighting LEDs and their final products had basically taken shape.

3. Deficiencies of existing LEDs for general lighting and their final product standards

Based on the content of the product standard system components in Part 1 of this article, we can examine the current (and to be promulgated) standards and the contents of these standards in Part 2 of this article. It can be found that some product standards that use LED as a light source have obvious defects, which are mainly manifested in the following aspects:

1. As a lighting source, due to its own particularity, it must have coordination requirements for the control device that cooperates with it. For example, in the performance standards of fluorescent lamps and the standards of HID light sources, "ballast design requirements" are given for the specifications of each lamp. This allows the control device to provide the light source with a normal operation, give full play to its strengths, and ensure the appropriate conditions for the service life of the light source when in use. However, this part of the requirement is not included in the performance standards of LED lighting that have been submitted for approval.

2. As a lighting source, it is usually installed in a lamp or similar device before it can be sold to consumers as a commodity. Due to the special nature of the light source, the lamp will also have matching requirements. For example, the standards for fluorescent lamps and HID lamps will give "lamp design requirements", requiring that the lamp design must pay attention to meeting the corresponding requirements of the light source and provide a good working condition for the light source, so that the strengths of the light source can be brought into play and the service life of the light source in the lamp can be guaranteed. However, this part of the content is not included in the relevant standards for lighting LEDs that have been submitted for approval.

3. Lamps are durable consumer goods, so in the safety requirements standard for lamps, the durability test item requires that the lamps can still work normally after the abnormal light source test and the replacement of the light source. During the thermal test, the temperature of the internal electronic components and parts must be measured to see if the surface temperature exceeds the tc value when the continuous operation reaches thermal equilibrium. The junction temperature of the LED light source during operation is an important parameter related to the light efficiency and service life, but there are currently no relevant requirements for measurement and restriction in the lamp standards.

The above three points are the most important links for lighting LEDs to enter the field of general lighting, and they play a role in connecting the past and the future for light source products and final lighting products. However, at present, there is a relatively obvious disconnection in this regard in our industry. The main reasons are two aspects. First, the manufacturers of LEDs and their modules have not yet conducted serious verification of such products in mass production, and have not been able to provide the corresponding curves of Vf-junction temperature and luminous efficiency-junction temperature for each model and specification of products under typical working conditions, nor have they provided the temperature limit values ​​of reference points measured for LED light sources under typical working conditions. Another reason is that the majority of lamp manufacturers have not fully understood and realized that, as a light source, LED, when applied to lamps, in addition to meeting general safety requirements, luminous efficiency requirements, and EMC requirements, must also ensure that the LED still maintains good working conditions when all possible most unfavorable conditions occur, so that the long life characteristics of LED can be fully utilized.

IV. Direction of Efforts and Outlook

In the process of formulating the relevant standards for general lighting LEDs that have been submitted for approval in 2008, a few knowledgeable people in China have considered the above issues, but due to the lack of sufficient verification data and relevant information, they cannot hastily write this part of the content into these standards. Only the industry standard "Performance Requirements for Light Emitting Diodes for General Lighting" has proposed a relatively rough characteristic curve of light efficiency-junction temperature and a measurement method for reference thermal resistance. This also shows the imperfection of these standards for LEDs as general lighting sources submitted for approval this year and the characteristics that they will need to be revised in the near future.

At the 2008 Beijing Olympic Games, the advantages of LED lighting products in the fields of landscape decoration lighting and display lighting were fully demonstrated. However, as professionals in this field, we should be aware that there are still many difficulties to be overcome on the road of LED entering the field of general lighting, mainly including:

1. As a responsible manufacturer of lighting LEDs and their modules, in addition to improving LED luminous efficiency, color rendering index , and maintaining color temperature consistency, we should also study and provide the Vf-junction temperature curve, junction temperature-luminous efficiency curve, and reference temperature measurement point limit requirements when working in lamps for each batch of production models and specifications of LEDs. This is not only for the design needs of the final lamp products, but also for the improvement of the technical level of LED light source manufacturers themselves and the development of their products.

2. As lighting designers and lighting manufacturers, you should fully understand the various curves and parameters provided by LED light source companies. In addition to ensuring that the lighting meets the requirements of safety, EMC and light distribution performance, you should also ensure that the designed lighting can provide a good working environment with sufficient margin for the LED under various possible adverse conditions. Only in this way can the LED be guaranteed to have a long life at a high light efficiency level.

3. As a scientific research, testing organization and professional standardization technical committee, we should study the characteristics of lighting LED and its modules, develop more suitable standard LED lamps, and propose better and more complete measurement methods, so that our testing level in this regard can reach the international advanced level. At the same time, we should guide LED manufacturers to test reliable Vf-junction temperature curve and junction temperature-light efficiency curve for each finalized LED light source, and complete the improvement of product standards in this regard as soon as possible.

Only when the majority of practitioners can correctly identify the applicable standards, understand the current deficiencies, improve these deficiencies, and implement this correct and comprehensive understanding into product design during the manufacturing process of LEDs and their final products, will the application level of lighting LEDs and lamps and other products make great progress, and the technical level of LEDs and their final products will reach a new height.