Patent ID: 8149101

Claim:
A display device comprising: a display unit which displays images represented by video signals received from an external information processing device external to the display device; a detector which detects an ambient environment condition; a memory which stores information indicative of an authorized user; operation buttons for on-screen display; a power supply; and a control unit coupled to the display unit, the detector, the memory, and the operation buttons which are in the display device, wherein, when the display device is powered on and then the control unit determines that power to the power supply has been shut off for longer than a threshold period of time, the control unit controls the display device to operate in an alarm mode of operation before the control unit determines whether information indicative of the authorized user is entered, the control unit controls the display device in a normal mode of operation to operate in a normal state according to an information signal from the external information processing device, the control unit controls the display device to enter into an anti-crime security mode of operation, when a state representing that the external information processing device may not be currently used is determined, the control unit cancels the anti-crime security mode of operation, when the control unit determines that information indicative of the authorized user for confirmation has been entered through the operation buttons for on-screen display by a user in the anti-crime security mode of operation, the control unit controls the display device to operate in the alarm mode of operation, when the control unit determines that information indicative of the authorized user for confirmation has not been entered by a user in the anti-crime security mode of operation, and the control unit performs an alarm operation in the alarm mode of operation.