Image display device, method for operating image display device, and endoscope system

An endoscope system comprising:

• an endoscope;
• and
• an image display device, wherein
• the image display device comprises:
• a communication unit configured to receive image signals from the endoscope;
• a plurality of circuits that include an image processing unit configured to process the image signals, and a display configured to display an endoscope image which the image processing unit outputs;
• a battery configured to supply electric power to the plurality of circuits;
• and
• a processor configured to switch a control mode in which the electric power is supplied to the plurality of circuits, from a normal mode of a case where the image display device receives the image signals, to any one of a plurality of standby modes in which power consumption is set to be lower than in the normal mode, wherein
• the processor switches the control mode, in a case where date and time are out of a preset scheduled use period, to a second standby mode in which power consumption is se to be lower than in a first standby mode of a case where the date and time are within the scheduled use period.