An
image display system capable of viewing an electronic image and an external
sight simultaneously, or selectively is disclosed. The
system comprises a plurality of
image display units including a controller for outputting image signals and at least one display unit capable of enabling switching operation with a predetermined
operation mode of a plurality of operation
modes including a mode for indicating the image signals from the controller; an external control device for outputting
mode control signals which address the
operation mode of the display unit; the controller of the respective
image display units being provided with an external control terminal for receiving the
mode control signals and an output terminal for outputting the
mode control signals supplied to the external control terminal; the outputs of different controllers are connected to the external control terminals thereof in turn so as to couple the plurality of controllers to the external control device in series, the remained control terminals are connected to the external control device, and the operation
modes of whole display units are collectively and forcibly and / or individually controlled through the respective controllers on the basis of the mode control signals from the external
control unit.