Introduction to test content and method of LED photoelectric characteristics

Semiconductor light-emitting diodes ( LEDs ) are new types of illuminators with high electro-optic efficiency, small size, long life, low voltage, energy saving and environmental protection. LED photoelectric test is an important and only means to verify the photoelectric performance of LED. The corresponding test results are the basis for evaluating and reflecting the current development level of China's LED industry. The standard for formulating LED photoelectric test methods is an important way to uniformly measure the photoelectric performance of LED products , and it is the premise that the test results truly reflect the development level of China's LED industry. This paper introduces several major aspects of LED photoelectric performance testing in combination with the latest national standards for LED test methods.

I. Introduction

Semiconductor light-emitting diodes (LEDs) have been widely used in indicators, signal lights, instrument displays, backlights, vehicle light sources, etc., especially the development of white LED technology , LED applications in the field of lighting is also more and more extensive. However, in the past, there was no comprehensive national standard and industry standard for LED testing. In production practice, it can only be based on relative parameters. Different manufacturers, users and research institutions have been controversial, which has led to serious development of the domestic LED industry. influences. Therefore, the national standard for semiconductor light-emitting diode test methods came into being.

Second, LED test method

Based on the actual needs of LED applications, LED testing needs to include a variety of aspects, including: electrical characteristics, optical characteristics, switching characteristics, color characteristics, thermal characteristics, reliability and so on.

1, electrical characteristics

The LED is a unipolar PN junction diode composed of a semiconductor inorganic material, which is one of the semiconductor PN junction diodes, and its voltage-current relationship is called a volt-ampere characteristic. It can be seen from Fig. 1 that the LED electrical characteristic parameters include forward current, forward voltage, reverse current and reverse voltage, and the LED must be driven by a suitable current and voltage to operate normally. Through the test of the electrical characteristics of the LED, the maximum allowable forward voltage, forward current and reverse voltage and current of the LED can be obtained, and the optimum working electric power of the LED can also be determined.

LED volt-ampere characteristic curve

Figure 1: LED volt-ampere characteristic curve

The test of the electrical characteristics of the LED is generally carried out using a voltage and current meter under the power supply of the corresponding constant current and constant voltage source.

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