OPTICAL UNIT FOR INSTRUMENT HAVING FUNCTION TO DISPLAY INFORMATION

PROBLEM TO BE SOLVED: To warn and display the information for caution and to improve convenience by designing the instrument in such a manner that the content of the display with an information function can be always visually checked from the outside of an exterior housing and that another display content can be displayed as overlapped. SOLUTION: In this unit, the content of the display is imaged as an erect virtual image at the position behind a display window by the optical path length of first and second mirrors when the display window is observed from the front side with a lid closed, so that the image can be visually recognized. The first and second mirrors 10, 11 are both half mirrors, and the mirror supporting faces of a case 9 are opened, and first and second subdisplay devices 12, 14 are disposed on the back of the first and second mirrors 10, 11, respectively. Each subdisplay device 12, 14 consists of a liquid crystal display panel or the like, and usually it is turned off. When a signal from a router is inputted, information or the like for caution can be warned and displayed as overlapped on the image of the display through the display window.