There are many types of x ray hand switches, one gear x ray hand switch, two gears x ray hand switch and three gears x ray hand switch. The first x ray hand switch presses the direct exposure film, the second gear hand brake has one more preparation button than the first gear hand brake, the first layer button is used for preparation, the second file is for exposure, and the purpose of adding preparation is to prevent false triggering, wherein Dental X-ray machines use more than one hand brake. First of all, the dental X is turned off whether it is a dental X-ray machine, a dental panoramic X-ray machine or a dental piece machine. Compared with the usual X-ray machine for whole body examination, the dose of X-ray is much smaller, so the X-ray radiation is small. In addition, the oral cavity area is small, generally not like the whole body examination, it is easy to falsely trigger and shoot the wrong position, causing mistakes. Therefore, the dental use of a handful of x ray hand switches can achieve the purpose of simple and convenient operation and saving money.