Imaging principle of security X-ray machine
Author： Shenzhen SHENFEI Electronic Technology Co., Ltd.Publish time：2018-06-30 17:28:06Views：480【SML】
Security X-ray machine is a familiar security device, but few people understand the imaging principle of security X-ray machine. This article will introduce the imaging principle of security X-ray...
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Security X-ray machine is a familiar security device, but few people understand the imaging principle of security X-ray machine. This article will introduce the imaging principle of security X-ray machine.
The security X-ray machine is mainly composed of X light tube and X light machine power supply and control circuit. The X light tube is composed of cathode filament (Cathod) and anode target (Anode) and vacuum glass tube. The X light machine power supply can be divided into two parts of high voltage power supply and filament power supply, in which the filament power is used for heating the filament and high voltage power supply of the high voltage power supply. At both ends of the cathode filament and the anode target, a high voltage electric field is provided to speed up the active electrons on the filament to flow to the anode target and form a high speed electron flow.
Three ways of producing X light in the imaging principle of the X-ray machine can produce X light: bremsstrahlung (Bremsstrahlung), electron capture and internal conversion. The mechanism of X ray produced by X-ray machine belongs to bremsstrahlung.
In the imaging principle of security X-ray machine, X-ray was discovered by Professor Lun chin in 1895. The vacuum tube emits the radiation line that can penetrate the object. In the electromagnetic spectrum, the energy is stronger, the wavelength is shorter, the frequency is higher, and the similar radiation lines have cosmic rays, X-ray and so on. To produce X-Ray, we must have X photospheric tube, and the basic structure of X photosphere tube must have:
1、Cathod;
2、Anode;
3、Vacuum glass tube（Evacuated glass envelope）;
4、Of course, there is power supply.
The generation of the line is first connected to the power source, through the step-down transformer, heating the X-ray tube filament, generating free electrons and gathering near the cathode. When the boost transformer provides high voltage electricity to the X - ray tube, the potential difference between the cathode and the anode increases sharply, and the free electrons in the active state are strongly attracted to make the beam forming electrons moving from the cathode to the anode to impact the structure of the anode tungsten target atom. At this time, energy conversion occurred, of which less than 1% of the energy formed X-ray, and the remaining 99% were converted to thermal energy. The former is mainly emitted by the X-ray tube window, the latter is emitted by the heat dissipation facility to provide the corresponding feedback signal, for the closed loop control, the pulse width modulation technology is used, the working frequency is about 30KHZ, the voltage and current closed loop is adjusted, and the overvoltage and over current protection are set up.
The security inspection machine is completed by sending the checked baggage into the crawler channel with the aid of the conveyor belt. After entering the passageway, the luggage will block the light barrier signal, and the detection signal is sent to the control unit, triggering the ray source to transmit the X ray beam. A very narrow fan shaped X ray beam passing through a collimator penetrates the luggage items on the conveyor belt to the dual energy detector. The high efficiency semiconductor detector turns the received X rays into electrical signals. These very weak current signals are quantized directly to the industrial control computer through the universal serial bus. After complex operation and image processing, high quality images are obtained.
These are the introduction of the principle of X-ray machine imaging. After understanding, we can better use the X-ray machine in practice, so as to make better use of security inspection to protect people's safety.
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