Is a camera without a Red Storm a good product?
Whether there is a red storm is only a matter of choice, not a technical problem. Light with a wavelength of more than 700nm is called infrared ray. Infrared rays above 900nm are basically free of red storms. The shorter the wavelength, the stronger the Red Storm, the higher the infrared sensitivity is.
At present, there are two kinds of mainstream infrared lamps on the market, one is with slight red burst, the wavelength is about 850nm, and the other is without red burst, the wavelength is about 940nm.
The sensitivity of the same camera at 850nm wavelength is much better than that at 940nm wavelength.
Therefore, 850nm, an infrared lamp with slight red burst, has higher efficiency and should be the first choice for infrared night vision monitoring.
The service life of the camera can reach more than 10 years. Can the service life of the infrared lamp reach this level?
To understand this problem, we must first understand the current manufacturing principle of infrared lamps.
At present, infrared lamps are mainly manufactured in three modes: 1. Halogen lamps; 2. Multi-chip LED; 3. Single chip LED.
Halogen lamp is a very old technology with high energy consumption, amazing calorific value and short service life. Due to its low use efficiency, it should withdraw from the market soon.
There are two main forms of multi-chip LED, one is 'Piranha', which contains 4 to 8 chips, and the other is an Array Illuminator, which contains 10 to 30 chips.
When it comes to the question of why to make multiple chips, the manufacturer's theory is that the infrared lamp is not far enough because of insufficient energy. If more chips are put together, the energy will increase and the irradiation distance will be farther.
In fact, this theory is misleading users.
It is undeniable that the camera needs more energy to illuminate a longer distance, but this does not depend on how much infrared light is emitted by the infrared lamp, but on how much infrared light is selected by the camera.
The multi-chip LED has no luminous focus, the luminous optical system is unreasonable, and the light efficiency is relatively low. These characteristics have become its fatal injuries.
Take the array LED as an example, the area is only the size of a penny coin, while the current is as high as more than 1000mA, and heat dissipation becomes a problem.
Moreover, the production requirements of multi-chip LED are very strict, and each chip cannot have any performance difference, otherwise, one chip will break down and the whole machine will be finished.
In general, compared with single-chip LED, the life of multi-chip LED is far from enough.
Comparatively speaking, single-chip LED is an ideal device for infrared lamps due to its simple production process, easy quality assurance, low calorific value and reasonable luminous optical system, and its theoretical service life can reach more than 100 thousand hours.
Therefore, for users, in order to ensure the service life of infrared lamps, high-grade LED chips should be selected first. High-grade chips have high power, good consistency, high luminous efficiency and excellent heat dissipation performance, A high-grade LED is much better than an ordinary LED, and of course the price is also very expensive.
Secondly, the optical system should be designed reasonably, with uniform illumination, high utilization rate and fast heat dissipation.
Third, strictly control the voltage, LED is very sensitive to voltage, the voltage is slightly higher, the LED tube core will burn; Slightly lower, the amount of light will be greatly reduced. It is best to match high-quality switching power supply.
Fourth, the input power cord is preferably high and low temperature resistant, super soft and bending resistant to adapt to different environments.
Is the infrared lamp the bigger the angle, the better?
Many manufacturers or engineers are trying their best to promote this view to everyone, so that everyone thinks that the larger the angle of infrared light is, the more room for lens selection is, and there will be no 'Flashlight' phenomenon when choosing wide-angle lens, and this kind of statement is actually very unscientific.
First of all, if a large-angle infrared lamp is matched with a small-angle lens, there is a waste of light.
For example, an infrared lamp has a luminous angle of 80 degrees (Equivalent to f3. 5mm lens angle)
If it is matched with an f 99% lens, then 1% of the light will be outside the lens field of view, that is to say, only of the light is useful and everything else is wasted.
In general, the angle of the infrared lamp is consistent with the angle of the lens, and the effect is the best.
Secondly, it is not that the larger the angle of the infrared lamp, the better the picture effect. In some occasions, the angle of the infrared lamp is too large, which will also affect the imaging.
For example, the corridor, because of its long and narrow characteristics, if the infrared lamp angle is large, the image of the nearby Edge is too bright, forming a 'light curtain' phenomenon, but the distant center is invisible, only a white phenomenon.
Therefore, the infrared lamp in the corridor should be 1/2 or 1/3 of the lens angle.
In general, the problem of infrared lamp angle is both a choice problem and a technical problem.
For lenses with different focal lengths, choose infrared lamps with appropriate angles. Under what conditions, the angle of infrared lamps should not be greater than the angle of lenses. For narrow and long environments, choose infrared lamps with smaller or even 1/3 angles than the lens.
Through the matching of narrow-angle infrared lamps, the ideal wide-angle effect can be obtained, with better effect and lower cost.