Patent ID: 8121666

Claim:
An image observation apparatus comprising: an image display section which includes a display surface for displaying an image; a supporting unit which includes a body portion provided in a separated state from the image display section in first horizontal directions which are parallel to a normal axis of the display surface, a coupling portion, and a link portion, one end of which is coupled to the body portion and an other end of which is coupled to the image display section, the supporting unit movably supporting the image display section in vertical directions, in the first horizontal directions, and in second horizontal directions which are perpendicular to the vertical directions and to the first horizontal directions, and defining an observing position between the image display section and the body portion; a first rotation unit which is configured to rotate the image display section and the link portion with respect to the body portion about a first vertical axis which passes a coupling portion between the body portion and the link portion, and which is configured to move the image display section in the second horizontal directions; a second rotation unit is configured to rotate the image display section with respect to the link portion about a second vertical axis which passes a coupling portion between the image display section and the link portion, the second rotation unit including a first gear which rotates together with the image display section about the second vertical axis; and an angle adjusting unit which includes a second gear meshing with the first gear, and a transmitting section configured to transmit a driving force that rotates the second gear by rotating the link portion about the first vertical axis, and which is configured to adjust a rotation angle of the image display section about the second vertical axis in a state that a display surface of the image display section faces the observing position, the angle adjusting unit being configured to adjust a reduction ratio ε of the first gear with respect to the second gear in a state of relation of ε={sin −1 ( D/d· sin θ)}/2θ−½ is satisfied, when an angle between a line joining the first vertical axis and the second vertical axis and a line joining the first vertical axis and the observing position is set to θ, a distance between the image display section and the first vertical axis is set to D, and a distance between the image display section and the observing position is set to d.