Projection screen transmitting device, projection screen receiving device and projection screen system

The utility model relates to the technical field of video transmission, and relates to a projection screen transmitting device, a projection screen receiving device and a projection screen system. The screen projection transmitting device comprises a video input port used for inputting a first video signal; the USB input port is used for inputting a second video signal; the input end of the signal switching module is respectively connected with the video input port and the USB input port, and the signal switching module is used for switching to output the first video signal or the second video signal; the first video transmission port is used for being connected with an external projection screen receiving device; and the signal transmitting module is arranged between the output end of the signal switching module and the first video transmission port and is used for converting the first video signal or the second video signal output by the signal switching module into an HDBaseT signal and transmitting the HD