Abstract: An optical visualizing apparatus for use in a head mounted display unit contains a liquid crystal shutter designed to allow a viewer to see both an image display and scenery outside of the image display at the same time. The apparatus contains a screen placed in front of the viewer's eyes, an optical visualizing unit to display an image on the screen, a mounting unit for supporting the optical visualizing unit in front of the viewer's face, and a control unit that can either suspend transmission of the image and allow clear sighting through the screen without the image or, if desired, simultaneous display of the image and sighting of scenery outside of the image.

Abstract: In order to give restriction to use of apparatus by children or minor persons or the like, a password is previously registered and when the power switch is turned on, a user inputs the password from the second remote controller. The controller controls the apparatus to turn on the image input switch SW only when the inputted password is matched with the registered password. Moreover, the controller displays, when the predetermined period has passed from initiation of image display, a warning for health of eyes on the liquid crystal display means and continues image display only when the will for continuous display such as repeated input of the password is indicated.