Various Types of Door Peep-hole and Their Usages

The common name of gate door viewer is cat's eye. Cat's eye is a kind of small optical instrument installed on the door of a house. It is also called cat's eye because the light is refracted through it and looks like the light from Persian cat's eye at night. Security door viewer peephole is convenient for residents to observe outdoor conditions. It has become a necessity for home safety.

 

 

1. Composition of Door Peep-hole

Like telescopes and microscopes, door peep-hole is composed of objective lenses and eyepieces. The objective lens is concave lens and the eyepiece is convex lens, but the focal length of the objective lens is short and the focal distance of the eyepiece is long. The focal length of the eyepiece should be equal to or greater than the sum of the distance between the objective lens and the eyepiece (the length of cat's eye) and the focal length of the objective lens. The length of the door peep-hole is about 3cm.

 

The focal length of the objective lens is very short. It makes the outdoor people or objects become the virtual image of standing and shrinking. This image just falls within the focus of the eyepiece. Finally, a shrinking upright virtual image is obtained. This image is just near the sight distance of human eyes, so the situation outside the door can be seen  clearly.

 

 

2. Type of Door Peep-hole

According to the intelligent degree of the equipment, the door peep-hole can be divided into ordinary door peep-hole and intelligent door peep-hole with camera.

 

According to the size of the observation range, the door peep-hole can be divided into super wide angle door viewer, wide angle peephole, small range door peep-hole and mini door peep-hole.

 

According to the material used, the door peep-hole can be divided into chrome plated door peep-hole and brass door peep-hole.

 

According to the installation length, if the door hole viewer is 18mm, it corresponds to 15mm door peep-hole, 23mm to 20mm door peep-hole, 28mm to 25mm door peep-hole, 38mm to 35mm door peep-hole, etc. There are many specifications. They are sold in hardware stores and DIY is also more convenient.

 

 

3. The Function of Door Peep-hole

Generally speaking, looking out through the front door peephole viewer from the inside, all the scenes can be seen in the field of view of about 120 degrees outside the door, but anything inside can not be seen through the door peep-hole from the outside. If this door peep-hole is installed on the door of public housing or private residence, it can play a certain role in the anti theft and security of the family.

 

Generally, there is no door peep-hole in the interior door, which is basically installed on the security door of the gate. There are various types of door peep-holes on the market, so the most suitable one can be selected according to the actual situation.

 

Wenzhou Zhongwang Hardware Co., Ltd. is specialized in manufacturing a wide variety of small hardware, including house number, signs, pull, knob, door stop, hook, bolt, etc. Its detailed products include electronic peephole viewer,  LCD door viewer,  door scope peephole and so on. It has good service and reasonable price. Welcome to visit.