Duty ratio controls the function of vacuum on-off valve.

The function of duty ratio control vacuum on-off valve is to adjust the amount of gas entering and leaving the vacuum chamber by controlling the on-off time ratio of the valve, thus controlling the change of vacuum degree. According to relevant public information, the duty ratio control vacuum on-off valve controls the amount of gas entering and leaving the vacuum chamber by controlling the ratio of valve opening time to closing time. When the vacuum degree needs to be reduced, the opening time of the valve is longer than the closing time, the amount of gas entering the vacuum chamber increases, and the vacuum degree decreases. When the vacuum degree needs to be increased, the closing time of the valve is longer than the opening time, and the amount of gas entering the vacuum chamber decreases and the vacuum degree increases.