To reduce the amount of space needed to display an item, while still retaining meaning for the item, a reduced presentation is determined for the item. The ratio of the distance to the screen from the exit light refracting surface of the projection optical system and the distance to the image display apparatus from the incident light refracting surface of the projection optical system satisfies a condition that the ratio be less than twenty. On a first peripheral section of the roller, the teeth are placed in such a manner that they do not extend inside the side wall. A circumferential channel is disposed on a lateral surface of the annular base. The spring loaded platform displaces, and the distance of the probe tip to the platform is measured.