Basic knowledge of LED

- Jan 29, 2021-

1. Color temperature and brightness


Color temperature 

Unit: Absolute temperature (Kelvin, K)


     The color temperature is expressed in absolute temperature K, which is to heat a standard black body (such as platinum). When the temperature rises to a certain level, the color starts to change from red, orange, yellow, green, blue, indigo (blue-violet), and purple, gradually Change, using this characteristic of light color change, when the light color of the light source is the same as the light color of the black body, we call the current temperature of the black body the color temperature of the light source. When the color temperature is around 3000K, the light color becomes yellowish. When the color temperature is above 5000K, the light color becomes bluish. Lights of different color temperatures have different lighting and visual effects. Different color temperatures correspond to different colors of light as shown below. Different wavelengths give human eyes different color perceptions, from red, orange, yellow, green, blue, indigo (blue-violet), and purple. The sensitivity of the eye changes strongly with the wavelength.


     For example, under good lighting conditions, the eye's sensitivity to 550nm wavelength light (yellow light) is 20 times that of red or blue light. This is also an important reason why most car fog lights and street lights on roads use yellow light. Color temperature is a measure of color temperature, not the brightness of a lamp. The color temperature of the halogen lamp can be from 2300K to 7000K; the color temperature of the HID lamp is from 4200K to more than 8000K; the higher the color temperature of the lamp, the worse its penetration power to fog and rain (the less bright it is). Big manufacturers such as Philips only produce xenon lamps with a color temperature of up to 6000K. The following is the performance of different color temperatures:




Light color temperature and light effect


3000K yellow light, strong penetrating power

4200K white with yellow, original car with xenon lamp

5000K Light all white, the highest color temperature in European standard

6000K Light all white, slightly blue

6500K Daytime under the sun

7000-8000K white is obviously bluish



Blue light above 8000K, poor penetration, recommended color temperature around 6000K is just the whitest and slightly blue color temperature, which is easy for human eyes to accept, not easy to fatigue, and improves safety, while halogen lamps are poor.


2. Nine basic properties that need to be paid attention to when choosing LED light sources




 With the rush of the market, as consumers, you still have to be calm when choosing, scientifically analyze, and choose the best cost-effective light sources and lamps. Here are some basic properties:




1. The brightness is different and the price is different. The lamps used in the lamps should meet the laser class I standard.




2. Antistatic ability. Strong antistatic ability, long life, high price. Generally, only those with antistatic voltage greater than 700V can be used for lighting.




3. If the wavelength is the same, the color is the same, if the color is required, the price is high. It is difficult for manufacturers without spectroscopy to produce products with pure colors.




4. Leakage current is a unidirectional conductive luminous body. If there is a reverse current, it is called leakage. The leakage current is large, the life is short, and the price is low.




5. The light-emitting angle is different for different purposes. Special lighting angle, higher price. Such as full diffusion angle, the price is higher.




6. The key to different quality of life is life, and life is determined by light decay. Low light decay, long life, long life and high price.




7. The luminous body of the chip is a chip, and the price of different chips varies greatly. Chips in Japan and the United States are more expensive. Generally, the prices of chips from Taiwan and China are lower than those in Japan and the United States.




8. Wafer size The size of a wafer is expressed by side length, and the quality of a large wafer is better than that of a small wafer. The price is proportional to the size of the chip.




9. Colloid Ordinary colloid is usually epoxy resin. It is more expensive to add anti-ultraviolet and fire retardant. High-quality outdoor lighting should be anti-ultraviolet and fireproof. Each product has a different design. Different designs are suitable for different purposes. The reliability design of lighting includes: electrical safety, fire safety, applicable environmental safety, mechanical safety, health safety, safe use time and other factors. From the perspective of electrical safety, it should comply with relevant international and national standards.




Because it is a new product, China's national standards are lagging behind, but the country provides product qualification tests. The price of lighting products with international safety certification (such as GS, CE, UL, etc.) and national product quality certification is higher because these products are reliable in safety design. Consumers should pay attention to the authenticity of the certificate. There are not many manufacturers with international safety certification and national product certification.




In terms of health, the price of products designed with non-toxic materials is higher, especially for indoor lighting. Don’t be greedy for cheap and use odorous lighting. At present, only a few manufacturers use non-toxic materials to produce. The identification method can be used directly. Separately from nose, smelly products are much cheaper than odorless products. Toxins such as lead, mercury, and cadmium require professional analysis. From the perspective of applicable environmental safety, there is a reliable dust-proof and moisture-proof design, and the price of products with fire-proof, UV-proof and low-temperature cracking prevention is high.



3. Precautions for outdoor lighting installation




Grounding: The lamps must have good wiring and grounding according to the requirements of the manual. If the Class I lamps are not grounded, they become similar to Class 0 lamps;




Allowable voltage fluctuations: HCI ceramic metal halide lamps, HQI quartz metal halide lamps and NAV high-pressure sodium lamps require that the voltage fluctuations within a short period of time not exceed +/-5%, and the long-term allowable fluctuation range is +/-3%, which is more Large voltage changes will shorten the life of the lamp and cause color shift;




The use of light source: frequent switching will shorten the life of the lamp;




Ballast: The distance between the light source and the ballast is restricted, generally not more than 3 meters;




Starting current: Depending on different ballasts for HCI, HQI and NAV, the starting current of the lamp can be as high as 2 times the working current, so this current must be considered when designing the circuit, otherwise the switch will easily trip;




Luminous flux: The parameters of the light source are stable after 100 to 300 hours. The ignition position of the T type and TS type is horizontal, while the E type has a vertical lamp holder. When the light source has different ignition positions, its luminous flux, color temperature and life are all There is a significant difference;




Color deviation: For all HQI and HCI metal halide lamps, there may be color deviation between the lamp and the lamp. This color deviation is due to the influence of external factors such as power supply voltage, ballast and lamp design. Influencing factors of color temperature consistency:



Internal factors: the consistency of the arc tube (charged mercury, electrode gap, volume, status and size, etc.) determines the consistency of the lamp power and cold spot temperature, which all affect the density of the halide, which determines the relative color temperature of the lamp consistency. The current advanced level abroad, the relative color temperature tolerance of the same batch of light sources can be controlled at about +/-100K when leaving the factory, while the domestic advanced level is about +/-300K. For a 3000K metal halide lamp, the color temperature difference of 600K can be easily felt by the naked eye.



External factors: different ignition positions can differ by 600K, power supply voltage parameters, supporting capacitors, relevant industry standards, and rated power below 400W, the ballast adjustment rate must be ≤10%; but supporting Taitong lighting constant power electronic town The flow device can well prevent the color temperature deviation.




Number of installations: It is recommended that no more than 4 lights are connected in parallel on the same branch to reduce voltage changes. Different phase-to-phase voltages will also cause the color cast of the light source. For example, customers have special requirements for contrast and color rendering. , It is recommended that customers choose HCI ceramic metal halide light source, supporting constant power metal halide lamp electronic ballast, the price is more expensive;




Buried lamp installation matters: first install the pre-buried outer barrel for the buried lamp. When installing the light source, be sure to use toughened glass to tightly compress the waterproof silica gel, and tighten the screws diagonally evenly. It cannot be installed on the driveway of the square. The conventionally produced HID underground lights reserve a 0.5-meter three-core cable, and the external wiring should use a waterproof box. The waterproof level requires IP67. The company does not have a waterproof box (can be ordered separately from the company), and the underground lamp must have 20CM The above water-repellent layer, it is better to have a water-repellent trench; 10. Installation matters of underwater lights: reserve a 1-meter three-core cable for conventional underwater lights, and use a waterproof box for external wiring. The waterproof level requires IP68, and the company leaves the factory. It is not equipped with a waterproof box (can be ordered separately from the company). For safety reasons, underwater lights generally require a transformer. The waterproof rating of the transformer is IP44. Therefore, the underwater lamp’s anti-shock rating is Class III. The transformer must be installed on the shore of the pool. Installed underwater;




Flood (projection) lamp installation matters: When the flood (projection) lamp is installed with the light source, the tempered glass is well pressed against the waterproof silica gel. The angle of the floodlight can be adjusted according to the lighting design requirements. All flood (projection) lights, buried Lamps and wall lamps cannot be covered by obstructions. This distance is indicated on the label on the product. All lamps cannot be installed on combustible surfaces (combustible surfaces refer to objects that can burn at 130 degrees);




Specification of wire number and rated current: minimum cross-sectional area of wire


   rated current (A)   nominal cross-sectional area (mm2)


  ≤0.2 wire wire

  >0.2 and ≤3 0.5

  >3 and ≤6 0.75

  >6 and ≤10 1

  >10 and ≤16 1.5

  >16 and ≤25 2.5

  >25 and ≤32 4

  >32 and ≤40 6

  >40 and ≤63 10




Installation of light source: HID light source and electrical appliances must match, and must be well installed on the lamp holder. The light source cannot be installed with bare hands. The company's products are equipped with a pair of disposable film gloves in each set of lamps to install the light source;




Matching of light source and electrical appliances: A, sodium lamps have no distinction between American and European standards; B, metal halide lamps below 150W do not distinguish between American and European standards, and use the same electrical components as sodium lamps; C, 250W and 400W metal halide lamps It is divided into American standard and European standard, and the wiring and electric light source are matched strictly according to the requirements;




Installation of waterproof joints: all lamps with waterproof joints must be tightened, and if necessary, glass glue or silica gel shall be applied to the inlet holes of the waterproof joints;




Protection level description: IPXX means dustproof and waterproof, the first X means dustproof, and the second means waterproof. The specific definition is explained in the product catalog.




Protection level Brief description

0 No protection No special protection

1 Anti-dripping (vertical dripping) should have no harmful effects

2 15° drip-proof When the shell is tilted within 15° from the normal position, vertical dripping has no harmful effect

3 Anti-sprinkling water within 60° of vertical has no harmful effects

4 Splash-proof water splashing in any direction has no harmful effects

5 Water spray prevention, water spraying in any direction has no harmful effects

6 Protection against violent sea waves When violent sea waves or strong water spray, the amount of water entering the shell will not reach harmful levels

7 Prevent water immersion from affecting the specified pressure and time. When the lamp housing is immersed in water, the amount of water entering the housing will not reach harmful levels

8 Anti-diving influence can dive for a long time under the conditions specified by the manufacturer

Logo text and symbol description:



Rated maximum ambient temperature: t a 0C

Ampere: A Frequency: Hz Volt: V Alternating Current: AC Direct Current: DC Power: W (Watts)

Classified according to the form of protection against electric shock: Class I: No sign symbol Class II: "Return" Class III:  



GB specification: my country's national standard for lighting products is the GB7000 series, which corresponds to the IEC60598 series (EN60598 series). Since May 1, 2003, all electrical and electronic products sold in the Chinese market will be subject to the Chinese compulsory certification system, with the mark "" and the name of the certification mark "China Compulsory Certification" (the English name is "China Compulsory Certification" , English abbreviation "CCC", can also be referred to as "3C" logo). 3C certification includes electromagnetic compatibility (EMC) requirements. Among the lighting fixtures, Class III lamps do not require the corresponding 3C certification marks. For Class I and Class II lamps without the 3C and CQC certification marks, their electrical parts must have the corresponding 3C certification marks before they can be sold on the Chinese market.



There are four commonly used 3C certification marks: safety certification marks; safety and electromagnetic compatibility marks, fire certification marks, and electromagnetic compatibility marks.


4. The difference between floodlight and floodlight


What is LED flood light?




LED Downlights are also called spotlights, projection lights, spotlights, etc. They are mainly used for architectural decorative lighting and commercial space lighting. They have heavier decorative components and have round and square shapes. Yes, because heat dissipation is generally considered, there are still some differences between its appearance and traditional floodlights.




LED flood light features:




At present, the commonly used LED flood lights on the market basically use 1W high-power LEDs (each LED component will have a high-efficiency lens made of PMMA, and its main function is to secondarily distribute the light emitted by the LED, which is two Secondary optics), and a few companies have chosen 3W or higher power LEDs because of the good heat dissipation technology. It is suitable for large-scale occasions, lighting, buildings, etc.




What else should be paid attention to in the flood light?




1. High-purity aluminum reflector, the most accurate beam and the best reflection effect.


2. Symmetrical narrow-angle, wide-angle and asymmetric light distribution systems.


3. The light bulb can be replaced with an open-back type, which is easy to maintain.


4. The lamps are all attached with a scale plate to facilitate adjustment of the irradiation angle.




The LED flood light is controlled by a built-in microchip. In small engineering applications, it can be used without a controller. It can achieve dynamic effects such as gradation, jump, color flashing, random flashing, and gradual alternation. It can also be controlled by DMX. Realize the effects of chasing and scanning. At present, its main application places are probably these: single buildings, exterior wall lighting of historical buildings, building interior and exterior lighting, indoor local lighting, green landscape lighting, billboard lighting, medical and cultural and other specialized facility lighting, bars, Atmosphere lighting in entertainment venues such as dance halls, etc.




What is LED flood light?




The LED flood light is a point light source that can illuminate uniformly in all directions. Its illumination range can be adjusted arbitrarily, and it appears as a regular octahedron icon in the scene. Floodlights are the most widely used light source in the production of renderings. Standard floodlights are used to illuminate the entire scene. Multiple floodlights can be used in the scene to produce better results. Floodlights are the most widely used light source in renderings. Multiple floodlights can be used in the scene to coordinate their effects to produce better results. It is to illuminate the object uniformly in all directions from a specific point. It is best to use it as an analogy to light bulbs and candles. Floodlights can be placed anywhere in the scene. For example, it can be placed outside the camera range or inside an object. It is common to use many different colored floodlights in the scene at a distance. These floodlights can project and blend the darkness on the model. Because the floodlight has a relatively large illumination range, the illumination effect of the floodlight is very easy to predict, and this kind of light has many auxiliary uses, for example, if the floodlight is placed close to the surface of the object, it will be on the surface of the object. It produces a bright light.




It should be noted that floodlights cannot be built too much, otherwise the renderings will appear dull and dull. Therefore, in the usual rendering of renderings, pay more attention to the impact of lighting parameters and layout on the light perception of the entire renderings scene, accumulate more experience, and master the lighting matching skills.




Features of floodlights:




Floodlights illuminate objects uniformly in all directions from a specific point. It is the best analogy to light bulbs and candles. Floodlights can be placed anywhere in the scene. For example, it can be placed outside the camera range or inside an object. It is common to use many different colored floodlights in the scene at a distance. These floodlights can project and blend the darkness on the model. Because the floodlight has a relatively large illumination range, the illumination effect of the floodlight is very easy to predict, and this kind of light has many auxiliary uses, for example, if the floodlight is placed close to the surface of the object, it will be on the surface of the object. It produces a bright light.


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