How to solve the image flickering problem of infrared camera

Some time ago, at a Suzhou 3D video distribution office, a dealer encountered some infrared camera flickering problems. Although it was not from our 3D video product, it still took responsibility for it and improved its products; tested by the technical department There are many trips to and from Huizhou in this way, and many tests have been carried out. Everyone has their own feelings and writes out to discuss with security colleagues who have the same problem.

Do some preliminary discussion on the possible flicker. That is to discuss the problem of image flicker caused by the continuous turning on of the infrared lamp. Their infrared originally adopted the solution of low illuminance plus photoresistor. In fact, under special circumstances, the size of the resistor should still be adjusted according to customer needs.

At present, ordinary infrared cameras generally use photosensitive elements to detect the illumination intensity of the environment, and generate a control signal according to the threshold determined in the design parameters to turn on the infrared lamp. The level of the threshold depends on the environment of use, user preferences, and the designer's consideration of the importance of various factors. The products of various manufacturers are different. Such as 20,10,5Lux. Etc. If the threshold is high, the turn-on time is earlier. It is possible that the camera has not yet converted from color to black and white, and the infrared lamp is turned on. This will have three disadvantages:

One is to extend the use time of the infrared lamp and affect the service life of the product; the second is to turn on the infrared lamp when the color image can be generated, which will cause the image quality to decline at this time; the third is to generate an infrared eye (infrared The eye is also determined by the principle, a phenomenon that people do not want to see). If the threshold is low, it is possible that the infrared lamp cannot be turned on in time when supplementary lighting is needed.

Why does the infrared camera flicker? As mentioned before, when the illumination intensity is below the threshold, the infrared lamp turns on to emit light. When it is higher than the threshold, it is closed. Let us consider the situation when the illumination intensity is slightly lower than the threshold: the photosensitive element detects that the illumination intensity is slightly lower than the threshold, and the infrared lamp is turned on to emit light-after the infrared lamp emits light, the detected illuminance increases (plus Infrared light coming back), and exceeding the threshold, controlling the infrared lamp to turn off-resulting in a decrease in the detected illumination, and controlling the infrared lamp to turn on again. This reciprocating motion caused the image to flicker. This happens because of the principle, not to mention normal, at least not the quality of the product.

So how to solve this problem?

The environmental illuminance detected by the photosensitive element is slightly lower than the threshold value is the condition of the problem, there are two cases:
One. At a certain time in the dusk, a short period of time, this problem occurs. If you do n’t want to increase the cost, use a general heart tablet. Our idea is to explain the reasons to the user and tolerate it.
two. This problem must be solved when the lighting intensity is stable.
1. Change the threshold.
In the same type of product, the threshold is also different, there is dispersion. The problem may be solved by replacing a product.
The manufacturer provides products with different design thresholds for replacement.
Products with higher threshold design parameters are less likely to flicker.
2. Change the environment
Change the intensity and angle of the lighting.
Change the installation angle of the camera a little, and move it up, down, left, or right, and the illuminance detected by the detector will change a lot, and it will leave the vicinity of the threshold to solve the flicker problem.
3. Adopt high quality low illumination camera heart with backlight compensation and anti-glare, especially the dedicated IR lens;

In addition, when someone or other objects near the camera reflect infrared light, it will cause the detected illuminance to change repeatedly, causing flicker. For example, when doing demonstration tests and inspections, the camera is installed at a low position, and an object blocks the camera at close range.

This is not a problem, when the camera is in the normal installation position, this phenomenon will naturally disappear. For example, as long as you are careful not to let the infrared light be directly reversed to the photosensitive element from a short distance.

According to our recommendation, the customer finally chose the second option, because for each and the third, they are unlikely to operate by themselves.
I wonder if there are more suitable treatments for my friends? Can discuss, we are also studying.