FIG. 3B is a diagram illustrating the operation display unit 2 in which a two-dimensional code is displayed on the display device 20 after the “DISPLAY TWO-DIMENSIONAL CODE” is selected on the menu screen illustrated in FIG. 3A. The user reads the two-dimensional code screen of the display device 20 with a mobile terminal 3 such as a smartphone, so that the mobile terminal 3 accesses the URL included in the two-dimensional code. FIG. 3C is an example in which the user is reading the two-dimensional code screen of the display device 20 with the camera of the mobile terminal 3. As a result, the user can refer to detailed explanations on the Web on the mobile terminal 3. Although a form in which the arrow keys 212 and the OK key 216 are used in the present example, in a case where a touch panel display is employed for the display device 20, there may be such a form in which the “DISPLAY TWO-DIMENSIONAL CODE” is selected on the touch panel.

FIGS. 4A through 4D are conceptual diagrams illustrating a frame rate of the camera of the mobile terminal 3 and a refresh rate of the display device 20. In FIGS. 4A and 4B, situations in a normal display setting (hereinafter referred to as a normal mode) are illustrated, and, in FIGS. 4C and 4D, situations in a two-dimensional code display setting (hereinafter referred to as a code display mode) are illustrated. The present embodiment is a form in which the refresh rate of the display device 20 are switched between the normal mode and the code display mode.