1. Basic concepts of luminous flux
(1) Definition
Luminous flux refers to the amount of light emitted by a light source per unit time, and it is a key indicator for measuring the total amount of light emitted by a light source. Essentially, luminous flux describes the visible light energy radiated by a light source per unit time, which is entirely based on the response characteristics of the human eye to light. That is to say, luminous flux is not all the electromagnetic radiation energy actually emitted by the light source, but the portion of radiation power that can be perceived by the human eye.
(2) Unit
The unit of luminous flux is lumens (lm). 1 lumen is defined as the luminous flux passed by an international standard candle light source within a unit solid arc angle. Due to the fact that the entire spherical area is 4 π R ², a luminous flux of 1 lumen is equal to 1/4 π of the luminous flux emitted by 1 candle. This unit system provides a unified standard for measuring and comparing luminous flux.
(3) Physical significance
Luminous flux reflects the total visible light energy emitted by a light source per unit time, which directly determines the brightness of the light source. The greater the luminous flux of the light source, the more light it emits, and the brighter the lighting effect. Therefore, luminous flux is one of the important parameters for evaluating the performance of a light source.
2. Factors affecting the linear light flux of LED
(1) Light source characteristics
As the core component of LED linear lamps, the luminous efficiency, wavelength, and packaging form of LED chips directly affect the luminous flux. LED chips with high luminous efficiency can generate more light flux at the same power. For example, for the 555nm yellow green light that the human eye is most sensitive to, a power of 1W can be converted into a luminous flux of 683 lumens, which is the maximum light conversion efficiency. For other colors of light, such as 650nm red, 1W of light is only equivalent to 73 lumens, mainly due to the insensitivity of the human eye to red light. In addition, the packaging form of LED chips can also affect the luminous flux. Reasonable packaging design can improve the efficiency of light extraction, thereby increasing luminous flux.
(2) Drive circuit
The driving circuit provides stable current and voltage for LED chips, and its performance directly affects the luminous efficiency and stability of LED chips. High quality driving circuits can ensure that LED chips operate at their optimal working conditions, thereby increasing luminous flux. For example, some advanced driving circuits adopt constant current driving technology, which can effectively avoid the impact of current fluctuations on LED chips and ensure the stability of light flux. Meanwhile, the efficiency of the driving circuit also affects the energy consumption of the entire lamp. An efficient driving circuit can reduce energy consumption and improve energy utilization efficiency.
(3) Optical Design
Optical design controls and distributes light through optical components such as lenses and reflectors, which can significantly affect the luminous flux output of LED linear lamps. Reasonable optical design can improve the utilization of light, reduce light loss, and thus increase effective luminous flux. For example, LED linear lights designed with non imaging optics can optimize the propagation path of light, allowing more light to reach the target area and improve the lighting effect.
(4) Environmental factors
Environmental factors such as temperature and humidity can also affect the luminous flux of LED linear lamps. High temperature can lead to a decrease in the performance and luminous flux of LED chips. Generally speaking, the luminous flux of LED chips decreases with increasing temperature, and for every 10 ℃ increase in temperature, the luminous flux may decrease by 5% -10%. Excessive humidity may affect the packaging materials and driving circuit performance of LED chips, thereby affecting the luminous flux. Therefore, in the design and use of LED linear lights, it is necessary to consider the impact of environmental factors and take corresponding measures for protection and heat dissipation.
3. Measurement methods and standards for luminous flux
(1) Measurement method
The main methods for measuring the linear light flux of LED include integrating sphere method and distributed photometer method. The integral sphere method is to place an LED linear lamp inside an integral sphere and calculate the luminous flux by measuring the reflected light on the inner wall of the integral sphere. This method is suitable for LED linear lights of various shapes and sizes, and the measurement results are relatively accurate. The principle of distributed photometry is to measure the luminous intensity of LED linear lamps in different directions, and then calculate the luminous flux based on the distribution of luminous intensity. This method can obtain the light distribution characteristics of LED linear lights, but the measurement process is relatively complex.
(2) Measurement standards
In order to ensure the accuracy and consistency of luminous flux measurement, a series of relevant standards have been developed internationally, such as IEC 62717 and IEC 62722. These standards specify the requirements for marking, size, power, luminous flux, correlated color temperature and color rendering index, lifespan, testing methods, etc. of LED lights. For example, IEC 62717 mainly specifies the marking position, rated luminous flux, color, etc. of LED lamps; IEC 62722 specifies that the initial luminous flux must not be less than 90% of the rated luminous flux.
4. The Importance of Luminous Flux in LED Linear Lamp Applications
(1) Lighting effect evaluation
Luminous flux is one of the important indicators for evaluating the lighting effect of LED linear lamps. The larger the luminous flux, the higher the illumination range and brightness of the lamp, which can better meet the lighting needs of different scenes. For example, in places such as shopping malls and offices, high luminous flux is required to ensure sufficient lighting brightness; In some artistic lighting or ambient lighting scenarios, although the luminous flux requirements may be relatively low, reasonable design is still needed based on specific needs.
(2) Energy efficiency considerations
The luminous flux is closely related to the energy efficiency of LED linear lamps. At the same power, the higher the luminous flux, the more efficient the lamp is in converting electrical energy into light energy, and the more fully utilized the energy. Therefore, when choosing LED linear lamps, in addition to considering power, it is also necessary to focus on their luminous flux parameters to ensure the selection of high-efficiency and energy-saving products.
(3) Product Design and Optimization
In the design process of LED linear lamps, luminous flux is an important design parameter. Designers need to choose LED chips, driver circuits, and optical designs reasonably based on the application scenarios and performance requirements of the product, in order to achieve the best light flux output. At the same time, by continuously optimizing product design, improving luminous flux and energy efficiency, the energy consumption and operating costs of the product can be reduced, and market competitiveness can be enhanced.
https://www.luxsky-light.com/led-linear-light/led-linear-tube-lights/pink-color-led-t8-tube-light-18w-for-meat.html
