Ocular optics system having at least four reflections occurring between curved surfaces

Abstract

The invention relates to an ocular optics system which forms no intermediate image, is reduced in terms of size and weight with well-corrected aberrations, and is best suited for use on face- or head-mounted image display devices, and provides an ocular optics system 7 comprising three juxtaposed optical surfaces 3, 4 and 5, wherein a space defined by three optical surfaces 3, 4, and 5 is filled with a transparent medium having a refractive index greater than 1, at least two optical surfaces 3 and 4 of these three optical surfaces are defined by curved surfaces concave on a pupil position side of the optics system, and at least four reflections occur between curved surfaces 3 and 4.

Description

BACKGROUND OF THE INVENTIONThe present invention relates generally to an ocular optical system, and more particularly to an ocular optical system intended for use with a head- or face-mounted image display device which is mounted on the head or face of the user to project images into the user's eyeballs.In recent years, helmet or goggle-type of head-mounted or face-mounted image display devices have been developed for virtual reality purposes or with a view to allowing individuals to enjoy wide-screen viewing.For instance, JP-A-2-297516 discloses an optical system made up of a 2D display device 11 for displaying images, an objective collimating lens 12 and a parallel transparent plate 13 having off-axis paraboloidal mirrors on both its ends, as shown in FIG. 6. Light beams leaving the 2D display device 11 for displaying images are converted by the objective collimating lens 12 into parallel beams, which are then subjected to first transmission through a parallel surface of the paral...

AI Technical Summary

Benefits of technology

In view of such problems associated with the prior art as mentioned above, an object of the present invention is to provide an ocular optical system designed to form no intermediate image, especially, an ocular optical system which is compact and light in weight with well corrected aberrations, and so is best suited for use on a head- or face-mounted image display device.

If the second and fourth reflecting mirrors are designed such that light rays are incident thereon at an angle of incidence exceeding the critical angle, the light rays are then reflected at the second and fourth reflection surfaces in the form of total reflection. This in turn enables light loss in an observed image to be reduced and make the observed image bright. This also enables the reflecting and transmitting regions to be superposed on each other so that the optical system can be made compact.

Problems solved by technology

A problem associated with an image display device of the type wherein an image thereof is relayed as shown in FIG. 6 is, however, that it needs not only an ocular optical system, but also a relay optical system, resulting in increases in the size and weight of the whole optical system as well as an increase in the amount of extension of the whole optical system from a person's head or face.

Therefore it is not fit for a head-mounted or face-mounted image display device.

The optical system for forming parallel beams as an intermediate image as well as the optical system for projecting an intermediate image into an eyeball produce some considerable aberrations because only the paraboloidal mirrors that have power.

The ocular optical system composed of a concave mirror, as shown in FIG. 7, also produces some considerable aberrations and so is detrimental to image quality, even though the concave mirror is defined by a toric surface as shown in FIG. 7.

Even by use of the transmission optical system 15 and toric surface 16, however, it is impossible to make adequate correction for coma, and other aberrations.

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