With conventional light sources, we have several units about LED lights. To urge readers about warm white led light bulb to understand and easy to use, the following will be a brief introduction to the relevant knowledge: 1, the luminous flux Luminous flux is the amount of light emitted by the light source per unit time, the radiated power of the human eye can be felt by that part of the radiation energy. It is equal to the product relative to the viewing rate of certain wavelengths of radiation energy per unit time and the band. The human of warm white led light bulb on different wavelengths of light relative the viewing rate, so the radiated power is equal to the different wavelengths of light, the luminous flux is not equal. The symbol of the luminous flux Φ, the unit is the lumen (Lm). Spectral radiant flux Φ (λ), can be drawn from the luminous flux formula: Φ = Km ■ Φ (λ) is gV (λ) dλ Formula, V (λ) - relative spectral luminous efficiency; Km of-radiation spectrum of light depending on the performance of the maximum units of Lm / W By the CIPM in 1977 to determine the Km value 683Lm / W (λm = 555nm). 2, the light intensity Light intensity by the light energy per unit area per unit time, energy and frequency is proportional to their intensity (ie, integral), can also be understood as the luminous intensity of the light source in a given direction of the light source The luminous flux dΦ in the direction of transmission in three-dimensional diagonal elements divided by the provider of the solid angle element dΩ The unit of luminous intensity is candela (cd), 1cd = 1Lm/1sr. The intensity of space in all directions and is the luminous flux. 3, the brightness Test the brightness of the LED warm white led light bulb and evaluate the LED street light optical radiation safety of the process, commonly used imaging method to measure microscopic imaging can be used for chip testing. The brightness of a light source on the surface brightness, is the luminous intensity in a given direction divided by the surface element dS of the surface element perpendicular to the orthographic projection of the given parallel to the surface area of the provider (warm white led high bay light bulb) The unit of brightness in candela per square meter (cd/m2 and). When the light-emitting surface and the measurement direction is vertical, then cos θ = 1. 4, illumination Illumination means the object is illuminated, the luminous flux per unit area accepted.Illumination and lighting, according to the surface and light source position in space, size and intensity of the light source and the angle of incidence of light Yu Xuancheng directly proportional to the light source to the illuminated surface is inversely proportional to the square of the distance. Surface illuminance E is the incident contains the luminous flux dΦ that point on the surface element divided by the quotient of the area of the surface element dS.