Current Situation Of Infrared Surveillance Camera

The video surveillance industry is now relatively mature and widely used in many industries and fields. With the rapid development of science and technology and the change of demand, video surveillance technology will become an important industry in the future. In the video surveillance industry, external camera equipment is a very important part. There are many kinds of camera equipment. How should the demander choose? What are the characteristics of infrared surveillance cameras?

1、 Overview of video surveillance technology

Video surveillance is now widely used in many industries. Video surveillance technology is a major category of security technology according to different disciplines, product attributes and application fields. This is an advanced and highly capable integrated system. It can transmit the image content of the monitored area and all dynamic scenes to the monitoring center at the same time, so as to realize automatic tracking and make the real-time processing situation clear at a glance.

In the TV monitoring system project, compared with the past, the outstanding point is that it requires not only daytime monitoring, but also nighttime monitoring. Objectively, the crime rate in today's society is increasing. With the improvement of people's security awareness, it has played a role in promoting the need for continuous day and night monitoring of important places and the maturity of day and night dual-purpose cameras. The role of the day and night infrared integrated camera is becoming increasingly prominent. It is not only adopted by important departments such as factories, schools, organs, warehouses, document rooms and other facilities, but also used in civil monitoring systems. Nationwide, infrared surveillance cameras are also widely used in residential areas, commercial buildings and other civil monitoring projects, which has gradually developed into a trend. This shows that people have higher and higher requirements for closed-circuit monitoring system engineering. It is more and more common for important places to be monitored continuously day and night.

2、 Principle and characteristics of infrared and infrared lamps

Let's first introduce infrared ray. Light is an electromagnetic wave, which has the same essence as radio waves. Its wavelength ranges from a few nanometers to about 1 millimeter. What the human eye can see is only part of it, which we call visible light. The wavelength range of visible light is 380nm~780nm. Visible light waves are divided into red, orange, yellow, green, blue and purple from long to short. The wavelength shorter than violet light is called ultraviolet light, and the wavelength longer than red light is called infrared light.

According to its infrared radiation mechanism, infrared lamps can be divided into two types: semiconductor solid light emitting (IRLED) infrared lamps and radiant infrared lamps. At present, the former is widely used.

The principle of infrared emitting diode (IRLED) infrared lamp is that the illuminant is composed of infrared LED matrix. The infrared emitting diode is made of a PN junction made of a material with high infrared radiation efficiency (commonly gallium arsenide GaAs), and a forward bias voltage is applied to inject current into the PN junction to excite infrared light. The spectral power distribution is the central wavelength of 830nm~950nm, and the half peak bandwidth is about 40mm. It is a narrow-band distribution, which can be felt by the CCD camera.

Irradiance for emission power of infrared light emitting diodes μ W/ m2. The maximum radiation intensity of infrared diode is generally in front of the optical axis, and decreases with the increase of the angle between the radiation direction and the optical axis. The angle of 50% of the maximum value of radiation intensity is called half intensity radiation angle, i.e. half power angle. The radiation angle of infrared light-emitting diodes with different packaging process is different. Generally speaking, its infrared radiation power is directly proportional to the forward working current, but when it approaches the maximum rated value of the forward current, the temperature of the device rises due to the heat consumption of the current, resulting in a decrease in the luminous radiation power. If the current of infrared diode is too small, its radiation power will be affected, but if the working current is too large, its service life will be affected, and even the infrared diode will be burned. The manufacturer takes this problem into full consideration when designing. At present, Sony Corporation of Japan adopts high-efficiency led, which makes the working time of the camera reach 50000 hours.