LED product photoelectric performance test standards
Electrical performance is particularly important for LED products, then we understand what LED products, photoelectric performance? Here we come together to learn what LED product optoelectronic performance test standards.
1. electrical characteristics
LED electrical characteristics of the parameters, including forward current, forward voltage, reverse current and reverse voltage, the test is generally used to test the voltage ammeter, constant current constant voltage source in the case of power supply. Through the LED electrical characteristics of the test can be the maximum allowable forward voltage, forward current and reverse voltage, current these parameters, in addition, you can get the best working LED power value.
2. Light characteristics
Mainly including luminous flux and light efficiency, light intensity and light intensity distribution characteristics and spectral parameters.
Luminous Flux and Light Effect: There are usually two methods for integrating sphere and variable angle photometry. Although the latter test results are the most accurate, but because of the longer time, the general use of the former. When testing with the integral sphere method, the measured LED can be placed in the center of the ball, can also be placed in the ball wall. After measuring the luminous flux, with the electrical parameters of the tester can be measured LED luminous efficiency, that is, light efficiency.
Light intensity and light intensity distribution characteristics: LED light intensity distribution is inconsistent, so its test results with the test distance and the size of the detector aperture changes, allowing each LED under the same conditions for light intensity test and evaluation, This results are more accurate.
Spectral parameters: mainly including peak emission wavelength, spectral radiation bandwidth and spectral power distribution. The spectral characteristics of the LED can be expressed by the spectral power distribution, through the spectral power distribution, you can also get the chromaticity parameters. General spectral power distribution of the test needs to be carried out by spectroscopy, the mixed light monochromatic light one by one to distinguish between the use of prisms and grating to achieve spectral.
3. Switch characteristics
Refers to the LED power and power off instantaneous light, electricity, color change characteristics, through this test can be LED in the instantaneous working state, material properties and other changes in the law, so as to understand the power loss on the LED.
4. Color characteristics
The main color coordinates, the main wavelength, color purity, color temperature and color, etc., the test method of spectrophotometry and integral method.
Spectrophotometric method: The spectral power distribution of the LED is measured by the monochromator spectroscopy, and then the corresponding chromaticity parameters are obtained by integrating the chrominance weighting function.
5. Thermal characteristics
Also refers to the thermal resistance and junction temperature, thermal resistance refers to the heat flow along the channel temperature difference with the power dissipation on the channel ratio, junction temperature refers to the LED PN junction temperature. There are two kinds of LED junction temperature test methods, one is the use of infrared temperature microscope or micro-thermocouple measured LED chip surface temperature, the other is to determine the current bias between the forward bias and junction temperature changes The relationship between the LED to determine the junction temperature.