Back light camera

Abstract

The invention discloses a back light camera which comprises a PWM (Pulse Width Modulation) signal generating circuit, a light source driving circuit and a light source switch induction control circuit, wherein the light source switch induction control circuit is respectively connected with the PWM signal generating circuit and the light source driving circuit; the PWM signal generating circuit is connected with the light source driving circuit; and the light source driving circuit further comprises a light source device which is used for emitting at least one light beam with a wavelength being 910-980 nanometers to an imaged object. The back light camera provided by the invention is ultra-long in service life which reaches one hundred thousand hours; and meanwhile, an LED (Light Emitting Diode) serves as the light source, so that the back light camera has the characteristics of convenience in operation, low energy consumption, environmental protection, and the like, and the cost is effectively lowered; the wavelength of the light beam emitting to the imaged object by the LED light source is 910-980 nanometers, and meanwhile the over exposure problem is solved; and the light is not reflected by the face of a shot person, the facial features are clearly distinguished and an image is free from white aperture, so that a monitored target is clearly displayed during a night monitoring process, the invisibility is strong and a monitoring position is difficult to be exposed.

Description

technical field [0001] The invention relates to a camera, in particular to a black light camera. Background technique [0002] There are two main types of cameras: passive and active. Passive infrared itself does not emit light sources, and relies on sensing devices to sense external light and heat to achieve monitoring. It is mainly divided into thermal infrared imaging technology and low-light night vision technology. [0003] Thermal infrared imaging technology relies on the temperature emitted by objects and human bodies to display images of objects and human bodies, so only the thermal outlines of people and objects can be seen, and the true face of objects cannot be seen clearly, so it is only suitable for object and human body detection. Moreover, the cost is high, the import of key components is highly dependent, and the selection area is small, which cannot meet the requirements of security engineering to see people or things clearly; low-light night vision technol...

AI Technical Summary

Problems solved by technology

[0003] Thermal infrared imaging technology relies on the temperature emitted by objects and human bodies to display images of objects and human bodies, so only the thermal outlines of people and objects can be seen, and the true face of objects cannot be seen clearly, so it is only suitable for object and human body detection. Moreover, the cost is high, the import of key components is highly dependent, and the selection area is small, which cannot meet the requirements of security engineering to see people or things clearly; low-light night vision technology requires a certain amount of moonlight, starlight and ambient light to see objects. If there is no light You can’t see anything, and the imaging is easily affected by the environment. If you encounter continuously changing weather, the imaging quality will be greatly affected, and it may happen that the imaging in some environments cannot be seen at all; The infrared type needs to increase the auxiliary infrared light, relying on the reflection of the emitted light to realize video surveillance. The active type is divided into visible light and invisible light. Visible light is easy to expose the target due to energy consumption and light pollution. Currently, it is mainly used in public places.

Invisible light currently mainly uses 850nm infrared for supplementary lighting. Although this method can also see the target, there is an infrared light burst, and it cannot be observed secretly. It is easier to expose the position of the light source.

At the same time, the image will be interfered by light waves, and the imaging is easily affected by the environment. If you encounter continuously changing weather, the imaging quality will be greatly affected, and it may happen that the imaging in some environments cannot be seen at all. In addition, there is a flashlight phenomenon with too concentrated light spots, and the problem of overexposure when the target is too close. Although some products claim to intelligently adjust the exposure rate, they have failed to achieve the effect of their publicity after testing.

Images