Abstract:
A manipulation panel that is a user interface includes a display unit that displays a screen, a touch panel that detects a tap performed to the display unit, and an abnormality detector that detects a situation, in which a message is displayed on the display unit, until the touch panel detects a second tap constituting a double tap since detecting a first tap. Manipulation panel displays a warning message about the situation detected by the abnormality detector on the display unit after the touch panel detects the second tap.