The illuminance sensor is a sensor used to detect the light intensity, referred to as illuminance for short. The working principle is to convert the light intensity value to a voltage value, which is mainly used for agricultural forestry greenhouse cultivation. Let the luminous flux on the bin dS be dΦ, then the illuminance E on the bin is: E=dΦ/dS. The unit of illuminance is lx (lux), and lux is also useful, 1lx=1lm/㎡. Illuminance represents the amount of illumination of the surface area of an object. In summer, under direct sunlight, the light intensity can reach 60,000 to 100,000 lx, outdoor without sun is 10,000 to 10,000 lx, bright indoor is 100 to 550 lx in summer, and 0.2lx under full moon at night.
An incandescent lamp can emit about 12.56lx of light per watt, but the value varies with the size of the bulb. Small bulbs can emit more lumens and fewer large bulbs. The luminous efficiency of fluorescent lamps is 3 to 4 times that of incandescent lamps. The life span is 9 times that of incandescent lamps, but the price is higher. However, about 30% of the light emitted by an incandescent bulb without a lampshade is absorbed by walls, ceilings, equipment, etc.; the poor quality and darkness of the bulb should be reduced. Many lumens, so only about 50% of lumens are available. Generally, when there is a lampshade and the height of the lamp is 2.0-2.4m (the distance between the bulbs is 1.5 times the height), lW bulb or 1m2 is needed for every 0.37m2 area, and 10.76lx is needed for 2.7W bulb area. The height of the bulb installation and the presence or absence of the lampshade have a great influence on the light intensity.
