Video doorbell as a convenient and practical products, since the late nineties so far, mainly used in commercial 

residential buildings, the rapid development of the scale, has now generally entered the urban residential 

high-rise residential. When used, households hear ringtones, like answering videotapes, accept visitors 

through the downstairs door call, dialogue, while the home of the visual extension can be received through 

the downstairs host camera video images, household observation extension display The screen to monitor

 the image to confirm the identity of the visitors, and finally decide whether to press the indoor extension of 

the button to open the door to connect the door of the electronic control door locks, allowing visitors to

 open the door to enter