LED Lighting Performance Must Be Tested(Part 1)

1. Luminous intensity detection

Light intensity is the intensity of light, which refers to the amount of light emitted at a specific angle. Due to the concentration of LED light, the inverse square law does not apply at close range. The CIE127 standard provides two measurement averaging methods for measuring light intensity A (far-field conditions) and measurement condition B (near-field conditions) to light conditions. The detector area is 1cm2 under both conditions. Generally, standard condition B is used to measure the luminous intensity. Our company provides pure white LED diode.

2. Luminous flux and light efficiency test

Luminous flux is the total amount of light emitted by the light source, that is, the amount of light. Detection methods include the following two:

(1) Integral method. In the integrating sphere, the standard lamp and the lamp to be tested are sequentially lit, and their readings on the photoelectric converter are Es and ED respectively.

(2) Spectrophotometry. Measure the spectrum of the lamp under test under the same conditions, compare and calculate the luminous flux of the lamp under test.

The luminous efficiency is the ratio of the luminous flux emitted by the light source to the power consumed, and the luminous efficiency of the LED is usually measured by the constant current method.

3. Spectral characteristic test

The spectral characteristics of LED detection, including spectral power distribution, color coordinates, color temperature, color rendering index, etc.

Spectral power distribution means that the light of a light source is composed of multiple color radiations of different wavelengths, and the radiation power of each wavelength is also different. This different wavelength distribution is called the spectral power distribution of the light source. Use spectrophotometer (monochromator) and standard light source for comparison and measurement.

The color coordinates represent the amount of light emitted by the light source with numbers on the graph. There are many coordinate systems for color coordinates, usually X and Y coordinate systems.

Color temperature is the amount of light color table (appearance color expression) seen by the human eye. When the light emitted by the light source is the same color as the light emitted by an absolutely black body at a certain temperature, the temperature is the color temperature. In the field of lighting, color temperature is an important parameter describing the optical characteristics of a light source. The color temperature theory is derived from black body radiation, which is obtained from the color coordinates of the black body locus through the color coordinates of the light source.

The color rendering index indicates that the amount of light emitted by the light source accurately reflects the color of the irradiated article. It is usually expressed as the total color rendering index Ra, that is, the arithmetic average of the color rendering index of the light source for 8 color samples. The color rendering index is an important parameter to measure the quality of the light source. It determines the application of the light source. Improving the color rendering index of white light LEDs is one of the important tasks of LED research and development.

The above information is provided by multi colours chip LED supplier.