How much do you know about LED light efficiency, LED thermal resistance, LED light decay?

24 views admin 2024-04-12

LED light failure, heat dissipation throughout the entire industry chain from chip manufacturing, packaging process, material selection, lighting development, the current industry on the concept of light failure, the cause and how to solve the lack of understanding, the theory has no authoritative explanation, the relevant national standards are difficult to introduce. The following are three aspects of LED light efficiency, LED thermal resistance and LED light decay.

LED light efficiency: The significance of distinguishing between transient light efficiency and steady-state light efficiency

The luminous flux (lm) emitted by the LED light source divided by the power consumed by the light source (W) is called the LED luminous efficiency, and the unit is lm/W. LED transient light efficiency refers to the luminous efficiency of the LED light source when it starts working, also known as the initial cold light efficiency.

Transient light efficiency is the short-time photoelectrical conversion characteristics of LED light source, which is related to the quantum excitation ability of chip and phosphor, colloidal refractive index, light transmittance, The reflectance of the bracket structure (reflective cup) is related to the conditions, and the chip junction temperature is basically unrelated. It only has the significance of measurement and comparison, and the transient light effect cannot represent the actual working state.

Steady-state light efficiency refers to the LED light source after working for a period of time into the thermal stability, the steady-state light efficiency includes in addition to the LED transient light and electrical characteristics, but also includes the temperature change state of the system heat transfer and heat dissipation, also known as the system light, which is the real working efficiency of the overall lamp.

LED thermal resistance: The significance of distinguishing the internal thermal resistance of the light source and the external thermal resistance of the light source

Thermal resistance usually refers to the resistance of heat flow through an object. Is determined by the nature of the material. The size of the thermal resistance is directly proportional to the length of the path through which the heat flow passes, inversely proportional to the cross-sectional area of the path, and inversely proportional to the thermal conductivity of the material. That is, Rth=L/Sλ

2. Distinguish the significance of internal thermal resistance of light source and external thermal resistance of light source

For the system, the LED thermal resistance includes: internal thermal resistance of the light source and external thermal resistance of the light source. The internal thermal resistance of the light source in the application is the packaging thermal resistance, which is related to light decay and life is an important indicator to measure the quality of the light source, which can not be changed for the lighting user, that is, the system design is helpless. The light efficiency of the system is inversely proportional to the thermal resistance of the system, and the lower the thermal resistance, the higher the light efficiency.

LED light failure: Light failure is the irreversible damage phenomenon that the light source components exceed the temperature limit

LED light failure refers to the LED after a period of lighting, its light intensity than the initial light intensity will be reduced, and can not be restored, that is, the reduced part is called LED light failure.

2. LED light failure is the irreversible damage phenomenon that the light source components exceed the temperature limit

Light decay means that the light intensity of the light source can not recover the initial value because the working temperature exceeds the limit value for a long time, which is called light decay, that is, the irreversible decline of luminous flux is the true light decay. LED light decay is the irreversible damage phenomenon that the light source components exceed the temperature limit