A control method applied in a display device is provided. The display device includes an image generator and a screen. The image generator is directed to output an output image. The screen is directed to operate in a first operation mode or a second operation mode. The screen has a first light-transmittance in the first operation mode and has a second light-transmittance in the second operation mode. The first light-transmittance is different from the second light-transmittance. In response to the screen operating in the first operation mode or the second operation mode, the image generator outputs the output image onto the screen in a light-emitting period and stops outputting the output image onto the screen in a non-light-emitting period after the light-emitting period.