Information display apparatus and navigation apparatus

A navigation apparatus which displays route guiding information necessary for route guiding due to a movement of a mobile object, comprising:

• a display device which is composed of a base material for transmitting a visible light beam and is provided with a display surface for displaying the route guiding information with it being opposed to an incident surface of the visible light beam;
• a light control device which is arranged so as to be overlapped with the incident surface of the display device, controls luminance of the visible light beam incident to the incident surface and is formed by a base material having transparency, and changes light transmittance in each of regions obtained by dividing a range overlapped with the display device;
• a recording device which records image data including the route guiding information in it;
• a display control device which controls display of the route guiding information in the display device based on the image data recorded in the recording device;
• a specifying device which specifies a display position of the route guiding information on the display device and specifies the region of the light control device corresponding to the display position;
• a transmittance control device which controls the light control device so as to reduce the light transmittance in the specified region;
• an imaging device which images the display device having the route guiding information displayed on it;
• and
• a video picture analyzing device which calculates a difference between a brightness component corresponding to pixels included in a display range of the route guiding information in video picture data corresponding to a video picture imaged by the imaging device and its vicinity range and a brightness component in the range in the image data including the route guiding information, so as to generate viewing information representing a viewing state of the route guiding information from the user based on the difference value,
• wherein the specifying device specifies the region on the light control device based on the viewing information, the transmittance control device reduces light transmittance in the specified region, and
• wherein, the video picture analyzing device executes edge detecting processes based on the data supplied from an overlapped video picture imaging section and the image data supplied from the display control device, and creates two line image data respectively according to the each data, and compares two line image data, and calculates unconformity T corresponding to respective cells composing each data, and compares the calculated result of the unconformity T with a predetermined threshold, and when the calculated value is larger than the threshold, the transmittance control device reduces the transmittance of the cells corresponding to the unconformity T.