Automatic exposure system of X-ray machine

The utility model relates to the field of production and manufacturing of X-ray machines, and discloses an automatic exposure system of an X-ray machine, which comprises a control unit, a multi-path driving circuit, a multi-path key circuit, a display screen and a power input conversion circuit. The control unit is used for controlling exposure starting and stopping of the X-ray machine according to the preset exposure frequency. Each drive circuit comprises a triode and a relay, the base of the triode is connected with the control unit, the collector is grounded, and the emitter is connected with the coil of the relay. The other end of the coil is connected with working voltage, and two ends of the contact are connected with the X-ray machine. And the multi-path key circuit is connected with the control unit and is used for inputting start-stop signals of the corresponding driving circuit. The display screen is electrically connected with the control unit and is used for displaying the exposure times; and th