LED junction temperature or average LED array junction temperature measuring method

Abstract

The invention discloses an LED junction temperature or average LED array junction temperature measuring method. A formula is established for the LED junction temperature, the effect of the self-heating process of an LED light source generated by a low current on the junction temperature is small, the thermal resistance between a thermostat and the LED light source is small, and the temperature of the thermostat replaces the LED junction temperature. Centroid wavelengths under different thermostat temperatures are measured, and the relational expression between the centroid wavelengths and the junction temperature is established. The junction temperature of an LED under the work condition can be conveniently worked out according to the formula and the centroid wavelengths of the LED light source under the measuring working conditions. According to the method, single-time calibration and multi-time measurement are achieved. Operation is easy, and the steps of the measuring method are similar to the steps of a peak wavelength method and a blue and white comparing method. Only a conventional optical and electrical test device is needed. The repeatability of the measurement on the centroid wavelengths is high, and the centroid wavelengths are used for representing that the junction temperature error is small. An LED pin is not in contact. The method can be used for measuring the junction temperature of a single LED and can be used for measuring the average junction temperature of an array composed of a plurality of LEDs, and the application range is wide.

Description

technical field [0001] The invention relates to an LED photoelectric detection method, in particular to a method for measuring the junction temperature of an LED or the average junction temperature of an LED array. Background technique [0002] LED (Light Emitting Diode) has many advantages such as small size, long life, high brightness, energy saving and environmental protection, and is considered to be the fourth-generation lighting source to replace incandescent lamps, fluorescent lamps, and high-pressure gas discharge lamps. It has been widely used in signal indication, LCD backlight, display, general lighting and other fields. The photoelectric color characteristics of the LED itself are closely related to the junction temperature, and an increase in the junction temperature will lead to a decrease in the luminous efficiency of the LED and a shortened lifespan. Therefore, how to quickly, scientifically and conveniently measure the LED junction temperature has become a ...

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Problems solved by technology

[0004] However, these methods still have many deficiencies. For example, due to the limitation of the material of the lamp housing, it is generally difficult to measure the voltage drop on each LED pin, the forward voltage method is difficult to use, and the peak wavelength method and valley wavelength method need Accurate measurement of peak or valley values ​​requires high-precision spectrometers and high-precision power supplies. In addition, the relationship between the peak wavelength of some LEDs and the junction temperature is not monotonous. The blue-white ratio method can only be used for the junction temperature of phosphor-converted white LEDs. , the radiation intensity method has relatively high requirements on the measurement environment and conditions, and the liquid crystal array thermal imaging method, micro-Raman spectroscopy, and luminescence spectroscopy have high requirements on the accuracy of testing instruments, and the related equipment is relatively expensive

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