With the development of agricultural greenhouse, more and more fruits and vegetables can be planted in winter.

In recent years, the agricultural market gradually began to face the problems of increasing competition and increasing demand. The traditional greenhouse can not meet the market demand, so we must find a way out. The gradual rise of equipment agriculture and the support of the national “Twelfth Five Year Plan” and other related policies have greatly promoted the development of greenhouse, greenhouse and other planting industries to the direction of modernization, science and technology, and intelligence. Smart greenhouse has become the inevitable trend of modern agriculture.

However, with the increase of the scale of agricultural greenhouses, the degree of wisdom becomes higher, and some agricultural managers do not know enough about the new technology and still manage according to the traditional way, which leads to frequent greenhouse management problems and higher risks. The first problem is the illumination. Due to the high frequency of severe weather such as fog and haze in winter, the traditional management of smart greenhouse will inevitably lead to uneven illumination, resulting in a significant reduction in crop production.

In solar radiation, the energy emitted by the part of the spectrum that is effective for photosynthesis of plants is called photosynthetically effective radiation; according to the demand of plants for growth light intensity, plants can be generally divided into heliophytes, mesophytes and shade plants.

The sunny plants, such as Cactaceae and Rosaceae, need to grow strong under strong light intensity;

Shade plants can grow well only under weak light intensity, such as most orchids, Araceae and ferns;

Mesophytes can grow well under sufficient light, but also can tolerate different degrees of shading. Most plants belong to this species.

The light intensity required by different plants is different. Generally, the light demand of sunny plants is higher, while that of shade plants is lower. Therefore, in the light intensity management of smart agricultural greenhouse, it is necessary to install light sensors to distribute the light amount reasonably according to different plants.

Working principle of illumination sensor

The light intensity sensor adopts the principle of hot spot effect, and mainly uses the detection components with high response to weak light. These sensing elements are actually like the photosensitive matrix of the camera. There is a wound electroplating multi contact thermopile inside. Its surface is coated with a black coating with high absorption rate. The hot contact is on the sensing surface, while the cold node is in the body. The cold and hot contacts generate thermoelectricity Potential.

In the linear range, the output signal is proportional to the solar radiation. The visible light through the filter irradiates the imported photodiode, and the photodiode converts the electric signal according to the illumination of the visible light, and then the electric signal enters the processor system of the sensor, so as to output the required binary signal.

Selection of illumination sensor

There are many kinds of illumination sensors, some of which even optimize the structure described above, especially in order to reduce the influence of temperature, the temperature compensation circuit is also used in the illumination sensor, which greatly improves the sensitivity and detection ability of the illumination sensor. For example, wall mounted illuminance sensor and shutter type illuminance sensor.

How to use illuminance sensor

The illuminance sensor should be installed in the open space around and there is no obstacle above the sensing surface. Adjust the horizontal position of the sensor, then fix it firmly, and fix the sensor firmly on the mounting bracket, so as to reduce fracture or intermittent interruption in windy days.

1. Installation method of wall mounted light intensity sensor: first drill holes in the wall, then put the expansion plug into the hole, and screw the self tapping screw into the expansion plug.

2. Installation method of louver box type illumination sensor: louver box type illumination sensor is generally used in outdoor weather station, and can be directly installed on the beam of weather station through supporting plate or bending plate.

This winter, the temperature is much colder than in previous years. The low temperature and weak light have a great impact on the normal photosynthesis of vegetables. When you control the temperature and light, you must coordinate. You can’t ignore one and lose the other and affect the yield of vegetables.

Editor in charge: CC

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