Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
1999-06-29
2001-03-13
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
C359S630000, C359S643000, C359S649000
Reexamination Certificate
active
06201647
ABSTRACT:
This application is based on applications Nos. H10-190456 and H10-190458 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display apparatus, and particularly, to an image display apparatus such as an HMD (head mounted display) for projecting a two-dimensional image displayed on a liquid crystal display into an observer's pupil through an eyepiece optical system to enable the observer to view an enlarged virtual image of the two-dimensional image.
2. Description of the Prior Art
Conventionally, various types of image display apparatuses have been proposed that project a two-dimensional image displayed on a display unit through an eyepiece optical system to display an enlarged virtual image of the original image. For example, image display apparatuses are known that employ a transmission-type liquid crystal display or a transmission-type screen as a display unit.
In an image display apparatus of the type that employs a transmission-type liquid crystal display, it is so difficult to achieve satisfactorily high density in the transmission-type liquid crystal that it is impossible to achieve a satisfactorily wide angle of view and satisfactorily high-resolution image display. Moreover, an image display apparatus of this type requires a space for accommodating an illumination optical system for illuminating the liquid crystal, and thus it is difficult to make it satisfactorily compact. In contrast, in an image display apparatus of the type that employs a transmission-type screen, it is possible to project a high-resolution image onto the transmission-type screen and thus achieve a satisfactorily wide angle of view and satisfactorily high-resolution image display. However, this image display apparatus, requiring a light source, a projecting optical system, a transmission-type screen, and an eyepiece optical system to be arranged therein, tends to have an unduly long total length, and thus it is even more difficult to make it compact.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a compact image display apparatus.
To achieve the above object, according to one aspect of the present invention, an image display apparatus is provided with a display unit and an eyepiece optical system. The display unit displays a two-dimensional image. The eyepiece optical system projects the two-dimensional image into an observer's pupil to enable the observer to view an enlarged virtual image of the two-dimensional image. In this image display apparatus, the optical axis of the eyepiece optical system is decentered from the visual axis of the observer's pupil.
According to another aspect of the present invention, an image display apparatus is provided with a display unit and an eyepiece optical system. The display unit displays a two-dimensional image. The eyepiece optical system projects the two-dimensional image into an observer's pupil to enable the observer to view an enlarged virtual image of the two-dimensional image. In this image display apparatus, the display unit is composed of a reflection-type screen or a reflection-type two-dimensional display device, and the eyepiece optical system has at least one reflecting surface and has an optical axis decentered from the visual axis of the observer's pupil.
In the present specification, the term “an observer's pupil” means the virtual pupil arranged in order to design an optical system and corresponds to the exit pupil of the eyepiece optical system, and the visual axis of the observer's pupil is fixed in a predetermined direction.
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Epps Georgia
Minolta Co. , Ltd.
Seyrafi Saeed
Sidley & Austin
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