With the security
problem is becoming the focus of attention, the development of security
monitoring technology was more and more paid attention by all sectors of
society, visible light surveillance cameras can no longer meet the
monitoring requirements, 24 hours of continuous monitoring equipment is a
important part in monitoring system now. To achieve 24x7 monitoring,
you need a night vision ip camera, the current cameras mostly with infrared night vision function. The infrared ip camera technology into a passive infrared technology and active infrared technology.
Passive infrared camera technology is the use of any object can radiate
electromagnetic waves principle above absolute zero (-273 ℃), due to
the different objects and even the strength of the radiation capacity of
the different parts of the same object, and the reflection of infrared
and use of objects with background radiation environment differences and
the scene itself, various parts of the difference of the radiation, the
infrared detector can strength ranging radiation signal is converted
into a corresponding electrical signal, and then amplified and video
processing, for human eye observation of the video image is formed, The
thermal image is able to render the various parts of the scene radiation
downs, which shows the characteristics of the scene. Different the same
goal thermal image and visible image, it is not the human eye can see
visible light image, but the target surface temperature distribution
image can not clearly identify the target of the detailed features, can
not meet the requirements as "evidence", and becuase of the high cost of
passive infrared ip cameras, they are used in the military field usually , few applications in the field of monitoring.
Active infrared camera technology is the use of infrared light emitting
diode to produce infrared radiation to produce the characteristics of
the ordinary network camera able to capture infrared light, auxiliary
lighting scene and environment in the human eye can not see, the use of
the network camera's image sensor can feel infrared light feelings the
surroundings reflected back infrared light to get a relatively clear
picture of black and white images, night vision surveillance. Therefore,
the infrared ip camera is now the majority of active
infrared technology, surveillance cameras use infrared lights to match.
Active infrared technology is relatively mature four forms:
Traditional LED infrared lamps: a certain number of infrared light
emitting diode matrix composed of luminous body, infrared emitting
diodes made by a material of high infrared radiation efficiency PN, plus
the forward bias voltage to the PN junction the injection current
excitation infrared light, spectral power distribution center wavelength
of 830 ~ 950nm, half peak bandwidth of about 40nm it is narrowband
distribution in the CCD feelings; second-generation array integrated
infrared light source: It uses state-of-the-art packaging technology on
the basis of the original LED infrared technology dozens of high
efficiency infrared crystals encapsulated in a plane, integrated IR
light-emitting chips in a small range, and made a "thermal isolation"
processing, so that the entire part can be placed in any size, any shape
of heat on the body, so as to solve the heat problem, no longer because
of the high temperature and hurt other peripheral electronic
components; third generation of dot matrix infrared light source: it is a
highly integrated LED array chip technology, single LEDArray output of
about 800mW to 3.6W electro-optical conversion efficiency is about 25%,
the light-emitting body is a single light source, the light-emitting
angle is adjustable; infrared laser light is a semiconductor laser, is
the use of semiconductor material in the complex process of the hole and
electron, and the decrease of electron energy levels and the release of
electrons to generating light energy, and then forming a laser photons
in the resonant photon propagation direction specification. Good
directional laser performance for the beam angle is small, the energy is
concentrated, and spread to the far distance there is still enough
light intensity, it is very suitable for long-distance lighting.
Active infrared ip camera with the infrared emission lights, its advantages is capable of showing
the details of the target characteristics, and lower cost. But the
disadvantage is that the irradiation distance is relatively short, The
imaging results easily affected by the environment, especially in the
fog, snow, rain, a little bad weather, mainly applied to the detection
of target; PIR network camera without the aid of an auxiliary light
source, the advantage to penetrate strong, irradiation distance. The
drawback is that only render target surface temperature distribution of
images, mainly used in finding the target.
The infrared ip camera market is quite confusing, mainly due to the industry's lack of unified
standards. For example, the infrared lamp irradiation distance is often
the highlight of each company propaganda, not quite the same with each
other, whether irradiation distance is measured under the conditions in
which environmental illumination and presented the picture quality is no
way informed that it is currently facing the most severe test of the
infrared ip camera market, to get rid of this problem has become the
focus of common concern between enterprises. Active infrared technology
early, only 5% efficiency, the development of efficient 25-30% LEDArray
technology, to meet the short-range to long-range infrared night vision
technology breakthroughs, and laser lighting technology is to achieve
long-distance night One of the best way to view monitor, and light
intensity than conventional light sources stronger and more long-range
night vision technology is a trend of the future night vision ip camera market. Active infrared technology and the integration of passive
infrared technology will be one of the trends of the future, the use of
passive infrared technology penetrating power, irradiation distance to
find the target, the use of the principle of active infrared lighting
acquisition target detail features can remote monitoring to provide
strong evidence. In addition, another night vision technology - shimmer
technology integration is also one of the future direction of
development, progress in the dim light and infrared technologies
respective period, taking into account the complementary nature of the
two, in addition to the existing based on technical difficulty, how to
LLL image and infrared image fusion to get better observe the effect of
the two technologies has become a hot research current night vision
technology development.