Display device and display control method

A display device which displays a video comprising:

• an external video processing unit configured to process an external video that is a video provided from outside of the display device;
• an on-screen display (OSD) video generation unit configured to generate an OSD video;
• a superimposed display unit configured to display the external video processed by the external video processing unit and the OSD video generated by the OSD video generation unit in a superimposed manner;
• and
• a phase difference detection unit configured to detect a phase difference between the external video generated by the external video processing unit and the OSD video generated by the OSD video generation unit;
• wherein the OSD video generation unit executes synchronization processing of synchronizing the OSD video with a synchronization signal of the external video while outputting the OSD video to the superimposed display unit when the external video and the OSD video are displayed in a superimposed manner, where the external video processing unit is configured to not output the external video to the superimposed display unit during execution of the synchronization processing and to output the external video to the superimposed display unit after completion of the synchronization processing;
• wherein the OSD video generation unit is configured to execute the synchronization processing by adjusting a length of a blanking period within an allowable time range that is able to be set as the blanking period;
• and
• wherein the OSD video generation unit is configured to determine an amount of adjustment of a length of a blanking period per frame and a number of frames to be used for the adjustment on a basis of the allowable time that is able to be set as the blanking period and a difference time corresponding to the phase difference detected by the phase difference detection unit.