Abstract: This image observation apparatus comprises: a head-mounted image display unit for displaying images, derived from video signals supplied to itself, on image display units corresponding to observer's left and right eyes respectively; a computer having specifications suitable to production of images displayed on the head-mounted image display unit and including an output part for outputting video signals expressing the images; and a controller being inserted in a signal transmission line between the computer and head-mounted image display unit and performing operator's optional operation regarding supply aspects of the video signals from the computer to the head-mounted image display unit.

Abstract: An image and voice communication system of the present invention has an image display element and a voice output element which are suitable for image and voice communication, and further includes a character image setting element capable of imaginatively setting a character image to be displayed on the image display element; a change command receive element for receiving from a communication mate a command signal for changing the character image; a character change element for changing the character image according to the command signal; and an element for causing the display element to display a character image changed by the character change element by supplying the changed character image to the display element.

Abstract: A head-mounted display apparatus wherein an image displayed on an image display device is projected on an observer's eyeball, which is designed so that the displayed image can be observed at a desired angle of view and at a desired magnification by making the projection magnification changeable. The head-mounted image display apparatus includes an image display device (11) for displaying an image, and a projection optical system for projecting the image displayed on the image display device (11) onto an observer's eyeball. The projection optical system is composed of a first relay optical system (12), a second relay optical system (13), and an ocular optical system (14). The second relay optical system (13), which is an afocal optical system, is rotatable about an axis (16) perpendicular to the optical axis so that the projection magnification is changed in three steps by the rotation of the second relay optical system (13).