The working principle of the smart induction doorbell

1. The smart induction doorbell, also called the welcome device, has appeared in recent years and is used for automatic door greetings in small shops and convenience stores. An electronic product with an anti-theft function, the induction doorbell obtains information about the existence of objects through various sensors, converts it into electrical signals, and uses the electrical signals to control a voice prompter that plays welcome words or music.

1. Light-sensitive principle. The light-sensitive smart doorbell uses the human body to reflect light. The photoresistor obtains a sufficiently large change in light. The circuit generates a changing current to trigger the circuit. The sensitivity is related to the reflectivity of the object. The light sensor Sensor doorbells are also related to ambient light levels.

2. Infrared induction principle, infrared pyroelectric sensor, the action is passive, it does not emit any signal itself, so it will not produce harmful electromagnetic interference. The central wavelength of infrared rays radiated by the human body is 9~10- -um, and the wavelength sensitivity of the detection element is basically unchanged in the range of 0.2~20--um. A window equipped with a filter lens is opened at the top of the sensor. The wavelength range of this filter that can pass light is 7 ~10--um, which is just suitable for the detection of human body infrared radiation. Infrared rays of other wavelengths are absorbed by the filter, thus forming an infrared sensor specially used to detect human body radiation.