1. Luminous flux
Definition: The sum of the visible light emitted in all directions by a light source into the air per unit time.
Unit: Lumen (lm)
Explanation: How much energy is converted into light energy per unit time when the light source is lit.
Example: A 18W LED down light has a luminous flux of 1800lm.
2. Luminous efficiency
Definition: The ratio of the total luminous flux (lumen, brightness) emitted by a light source to the electrical power (watts) consumed by that light source.
Unit: Lumen/watt (lm/w)
Explanation: The higher the luminous efficacy, the more efficient the conversion of electrical energy into light energy, and is an indicator of the lamp.
Example: A 18W led down light with a luminous efficacy of 100lm/w means that 100lm of light can be produced by consuming 1w of electrical energy.
3. Illuminance
Definition: The degree to which an object is illuminated, expressed as the amount of luminous flux received per unit area.
Unit: Lux (lx), i.e. lm/m
Explanation: A quantity used to indicate the intensity of light and the extent to which an object's surface area is illuminated.
Example: An area of 1m2 receives 100lm of luminous flux, the illuminance of this area is 100Lux.
4. Luminous Degradation
Definition: Luminous degradation means that the luminous flux of a lamp will be lower than the original luminous flux after a period of lighting, and this lower part is the luminous degradation of the LED.
Unit: Percentage (luminous flux decay / initial luminous flux)
Explanation: The percentage decrease in luminous flux of a lamp after a period of use.
Example: A down light with an initial luminous flux of 1800lm, after 10,000 hours of operation, the luminous flux becomes 1710lm.it is said that the down light has a light failure of 5% at 10,000 hours.
