Sony Patent | Display apparatus

Patent: Display apparatus

Drawings: Click to check drawins

Publication Number: 20210294091

Publication Date: 20210923

Applicant: Sony

Abstract

A display apparatus of the present disclosure includes an eyepiece display unit including an image display device and an eyepiece optical system that guides a display image displayed on the image display device to an eye point, in which an image magnification by the eyepiece optical system is twice or more, the eyepiece optical system is a coaxial system including a plurality of single lenses, at least one of the plurality of single lenses is an aspherical lens including a resin material, and the image display device displays, as the display image, an image for correction of distortion and chromatic aberration of magnification generated in the eyepiece optical system.

Claims

1. A display apparatus comprising an eyepiece display unit including an image display device and an eyepiece optical system that guides a display image displayed on the image display device to an eye point, an image magnification by the eyepiece optical system being twice or more, the eyepiece optical system comprising a coaxial system including a plurality of single lenses, at least one of the plurality of single lenses comprising an aspherical lens including a resin material, and the image display device displaying, as the display image, an image for correction of distortion and chromatic aberration of magnification generated in the eyepiece optical system.

2. The display apparatus according to claim 1, wherein the eyepiece optical system includes an eyepiece of a three-group three-lens configuration in which a first lens, a second lens, and a third lens are arranged as the plurality of single lenses in order from side of the eye point toward side of an image.

3. The display apparatus according to claim 2, wherein the first lens comprises a spherical lens having a positive refractive power including a material of a refractive index of 1.439 or more with respect to a d-line, and a lens surface of the first lens on the side of the eye point has a convex shape or a planar shape.

4. The display apparatus according to claim 2, wherein a maximum amount of generation of the chromatic aberration of magnification in the eyepiece optical system is 600 .mu.m or less.

5. The display apparatus according to claim 2, wherein the following conditional expression: 0.450

6. The display apparatus according to claim 2, wherein the following conditional expression: 0.400

7. The display apparatus according to claim 1, wherein the eyepiece optical system includes an eyepiece of a four-group four-lens configuration in which a first lens, a second lens, a third lens, and a fourth lens are arranged as the plurality of single lenses in order from side of the eye point toward side of an image.

8. The display apparatus according to claim 7, wherein the first lens comprises a spherical lens having a positive refractive power including a material of a refractive index of 1.439 or more with respect to a d-line, and a lens surface of the first lens on the side of the eye point has a convex shape or a planar shape.

9. The display apparatus according to claim 7, wherein a maximum amount of generation of the chromatic aberration of magnification in the eyepiece optical system is 600 .mu.m or less.

10. The display apparatus according to claim 7, wherein the following conditional expression: 0.450

11. The display apparatus according to claim 7, wherein the following conditional expression: 0.550

12. The display apparatus according to claim 1, wherein the eyepiece display unit includes a left eyepiece display unit and a right eyepiece display unit, the image display device includes a left-eye image display device arranged in the left eyepiece display unit, and a right-eye image display device arranged in the right eyepiece display unit, the eyepiece optical system includes a left eyepiece optical system and a right eyepiece optical system, the left eyepiece optical system being arranged in the left eyepiece display unit and guiding a left-eye display image displayed on the left-eye image display device to a left eye, the right eyepiece optical system being arranged in the right eyepiece display unit and guiding a right-eye display image displayed on the right-eye image display device to a right eye, the left eyepiece optical system and the right eyepiece optical system each include the plurality of single lenses, and an image magnification upon observation by both eyes is twice or more.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a display apparatus suitable for a head-mounted display, etc.

BACKGROUND ART

[0002] As a display apparatus using an image display device, an electronic viewfinder, an electronic binocular, a head-mounted display (HMD), etc. are known. In particular, the head-mounted display is used for a long period of time with a body of the display apparatus being worn in front of one’s eyes. It is therefore required that an eyepiece optical system and the body of the display apparatus be small-sized and light-weighted. In addition, it is required that an image be observable at a wide field angle of view and at a high magnification. An eyepiece optical system described in PTL 1 attains an optical system that achieves both high resolution and high magnification by using a plurality of lenses including a glass material having a high refractive index and high Abbe’s number.

CITATION LIST

Patent Literature

[0003] PTL 1: Japanese Unexamined Patent Application Publication No. H11-23984

SUMMARY OF THE INVENTION

[0004] Using the glass material having a high refractive index and high Abbe’s number leads to use of a glass lens having a high density, thus making the optical system heavy.

[0005] It is desirable to provide a display apparatus that makes it possible to provide high-definition beauty of an image while achieving a lighter weight and a wider angle of view.

[0006] A display apparatus according to an embodiment of the present disclosure includes an eyepiece display unit including an image display device and an eyepiece optical system that guides a display image displayed on the image display device to an eye point, in which an image magnification by the eyepiece optical system is twice or more, the eyepiece optical system is a coaxial system including a plurality of single lenses, at least one of the plurality of single lenses is an aspherical lens including a resin material, and the image display device displays, as the display image, an image for correction of distortion and chromatic aberration of magnification generated in the eyepiece optical system.

[0007] The display apparatus according to an embodiment of the present disclosure includes the eyepiece optical system of a coaxial system including a plurality of single lenses, thus optimizing the configuration of the single lenses. The image display device displays a display image for correction of distortion and chromatic aberration of magnification generated in the eyepiece optical system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is an explanatory diagram illustrating a first configuration example of an eyepiece display unit used in a head-mounted display, for example.

[0009] FIG. 2 is an explanatory diagram illustrating a second configuration example of the eyepiece display unit used in the head-mounted display, for example.

[0010] FIG. 3 is an explanatory diagram of image magnification.

[0011] FIG. 4 is a plan view of an overview of a display apparatus according to an embodiment of the present disclosure.

[0012] FIG. 5 is a side view of an overview of the display apparatus according to an embodiment.

[0013] FIG. 6 is an explanatory diagram illustrating a correspondence relationship between an output image to an image display device and an image actually visible through an eyepiece optical system having distortion.

[0014] FIG. 7 is an explanatory diagram illustrating a correspondence relationship between an output image to an image display device and an image actually visible through an eyepiece optical system having chromatic aberration of magnification.

[0015] FIG. 8 is an explanatory diagram illustrating an ideal light beam reaching position in an optical system of a focal length f and a light beam reaching position (an actual light beam reaching position) distorted by generation of distortion.

[0016] FIG. 9 is an explanatory diagram schematically illustrating an ideal light beam reaching position and an actual light beam reaching position in a case where marginal light beams are aligned and an amount of deviation between the ideal light beam reaching position and the actual light beam reaching position.

[0017] FIG. 10 is an explanatory diagram schematically illustrating ideal reaching positions of light beam of a plurality of colors.

[0018] FIG. 11 is an explanatory diagram schematically illustrating light beam reaching positions of a plurality of colors varied due to generation of chromatic aberration of magnification.

[0019] FIG. 12 is an explanatory diagram illustrating a green spectrum of a typical image display device.

[0020] FIG. 13 is an explanatory diagram illustrating a correlation between chromatic aberration of magnification generated in an optical system and an amount of deviation between light beam reaching positions of a short-side wavelength of a green color and a long-side wavelength of the green color in a case where only the green color is emitted.

[0021] FIG. 14 is an explanatory diagram schematically illustrating a relationship between magnitude of a field angle of view (FOV) as well as magnitude of an eye relief (E.R.) and a height of a light beam passing an outermost of a first surface of an eyepiece.

[0022] FIG. 15 is a cross-sectional view of lenses of an eyepiece according to Example 1.

[0023] FIG. 16 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 1.

[0024] FIG. 17 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 1.

[0025] FIG. 18 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 1.

[0026] FIG. 19 is a cross-sectional view of lenses of an eyepiece according to Example 2.

[0027] FIG. 20 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 2.

[0028] FIG. 21 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 2.

[0029] FIG. 22 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 2.

[0030] FIG. 23 is a cross-sectional view of lenses of an eyepiece according to Example 3.

[0031] FIG. 24 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 3.

[0032] FIG. 25 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 3.

[0033] FIG. 26 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 3.

[0034] FIG. 27 is a cross-sectional view of lenses of an eyepiece according to Example 4.

[0035] FIG. 28 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 4.

[0036] FIG. 29 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 4.

[0037] FIG. 30 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 4.

[0038] FIG. 31 is a cross-sectional view of lenses of an eyepiece according to Example 5.

[0039] FIG. 32 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 5.

[0040] FIG. 33 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 5.

[0041] FIG. 34 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 5.

[0042] FIG. 35 is a cross-sectional view of lenses of an eyepiece according to Example 6.

[0043] FIG. 36 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 6.

[0044] FIG. 37 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 6.

[0045] FIG. 38 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 6.

[0046] FIG. 39 is a cross-sectional view of lenses of an eyepiece according to Example 7.

[0047] FIG. 40 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 7.

[0048] FIG. 41 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 7.

[0049] FIG. 42 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 7.

[0050] FIG. 43 is a cross-sectional view of lenses of an eyepiece according to Example 8.

[0051] FIG. 44 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 8.

[0052] FIG. 45 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 8.

[0053] FIG. 46 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 8.

[0054] FIG. 47 is a cross-sectional view of lenses of an eyepiece according to Example 9.

[0055] FIG. 48 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 9.

[0056] FIG. 49 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 9.

[0057] FIG. 50 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 9.

[0058] FIG. 51 is a cross-sectional view of lenses of an eyepiece according to Example 10.

[0059] FIG. 52 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 10.

[0060] FIG. 53 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 10.

[0061] FIG. 54 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 10.

[0062] FIG. 55 is a cross-sectional view of lenses of an eyepiece according to Example 11.

[0063] FIG. 56 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 11.

[0064] FIG. 57 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 11.

[0065] FIG. 58 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 11.

[0066] FIG. 59 is a cross-sectional view of lenses of an eyepiece according to Example 12.

[0067] FIG. 60 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 12.

[0068] FIG. 61 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 12.

[0069] FIG. 62 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 12.

[0070] FIG. 63 is a cross-sectional view of lenses of an eyepiece according to Example 13.

[0071] FIG. 64 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 13.

[0072] FIG. 65 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 13.

[0073] FIG. 66 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 13.

[0074] FIG. 67 is a cross-sectional view of lenses of an eyepiece according to Example 14.

[0075] FIG. 68 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 14.

[0076] FIG. 69 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 14.

[0077] FIG. 70 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 14.

[0078] FIG. 71 is a cross-sectional view of lenses of an eyepiece according to Example 15.

[0079] FIG. 72 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 15.

[0080] FIG. 73 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 15.

[0081] FIG. 74 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 15.

[0082] FIG. 75 is a cross-sectional view of lenses of an eyepiece according to Example 16.

[0083] FIG. 76 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 16.

[0084] FIG. 77 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 16.

[0085] FIG. 78 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 16.

[0086] FIG. 79 is a cross-sectional view of lenses of an eyepiece according to Example 17.

[0087] FIG. 80 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 17.

[0088] FIG. 81 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 17.

[0089] FIG. 82 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 17.

[0090] FIG. 83 is a cross-sectional view of lenses of an eyepiece according to Example 18.

[0091] FIG. 84 is an aberration diagram illustrating spherical aberration of the eyepiece according to Example 18.

[0092] FIG. 85 is an aberration diagram illustrating field curvature and distortion of the eyepiece according to Example 18.

[0093] FIG. 86 is an aberration diagram illustrating chromatic aberration of magnification of the eyepiece according to Example 18.

[0094] FIG. 87 is an external perspective view of a head-mounted display as an example of a display apparatus as viewed obliquely from the front.

[0095] FIG. 88 is an external perspective view of the head-mounted display as an example of the display apparatus as viewed obliquely from the rear.

MODES FOR CARRYING OUT THE INVENTION

[0096] Hereinafter, description is given in detail of embodiments of the present disclosure with reference to the drawings. It is to be noted that the description is given in the following order.

0. Comparative Example

[0097] 1. Description of Display Apparatus according to Embodiment

[0098] 1.1. Overview of Display Apparatus according to Embodiment

[0099] 1.2. Description of Correction of Distortion and Chromatic Aberration of Magnification

2. Configuration Example and Workings and Effects of Eyepiece Optical System (Eyepiece)

3. Example of Application to Head-Mounted Display

4. Numerical Examples of Eyepiece Optical System (Eyepiece)

5. Other Embodiments

6. Comparative Example

[0100] FIG. 1 illustrates a first configuration example of an eyepiece display unit 102 used in a head-mounted display, for example. FIG. 2 illustrates a second configuration example of the eyepiece display unit 102 used in the head-mounted display, for example.

[0101] The eyepiece display unit 102 includes an eyepiece optical system 101 and an image display device 100 in order from side of an eye point E.P. along an optical axis Z1.

[0102] The image display device 100 is, for example, a display panel such as an LCD (Liquid Crystal Display) or an organic EL display. The eyepiece optical system 101 is used to magnify and display an image displayed on the image display device 100. The eyepiece optical system 101 is configured by, for example, an eyepiece including a plurality of lenses. With use of the eyepiece optical system 101, an observer observes a virtual image Im that is displayed in a magnified manner. A sealing glass, etc. adapted to protect the image display device 100 may be disposed on a front surface of the image display device 100. The eye point E.P. corresponds to a position of a pupil of the observer and also serves as an aperture stop STO.

[0103] Here, FIG. 1 illustrates a configuration example in a case where a size of the image display device 100 is smaller than a diameter of the eyepiece optical system 101. FIG. 2 illustrates a configuration example in a case where the size of the image display device 100 is large than the diameter of the eyepiece optical system 101.

[0104] In a head-mounted display having a high viewing angle with a field angle of view over 70.degree. and using the coaxial eyepiece optical system 101, the image display device 100 is often larger than the diameter of the eyepiece optical system 101. In such a head-mounted display, an image magnification Mv is suppressed to be small, but a focal length f becomes relatively long. This leads to a concern that the eyepiece optical system 101 has a long total length. In addition, the size of the eyepiece optical system 101 is sometimes limited not by the size of the eyepiece optical system 101 but by the size of the image display device 100. This further leads to an issue of unsuitableness for a reduction in size.

[0105] For example, as illustrated in FIG. 1, in a case where the size of the image display device 100 is small, the size of the entire eyepiece display unit 102 is limited by the size of the eyepiece optical system 101. In contrast, as illustrated in FIG. 2, in a case where the size of the image display device 100 is large, the size of the entire eyepiece display unit 102 is limited by the size of the image display device 100.

[0106] It is to be noted that the image magnification Mv is expressed by Mv=.alpha.’/.alpha.. As illustrated in the upper part of FIG. 3, .alpha. denotes a field angle of view in a case where the eyepiece optical system 101 is not provided. In addition, as illustrated in a lower part of FIG. 3, .alpha.’ denotes a field angle of view (field angle of view with respect to the virtual image Im) in a case where the eyepiece optical system 101 is provided. In FIG. 3, h is a maximum image height of an image to be observed, and is, for example, a maximum image height of an image displayed on the image display device 100. For example, in a case where the image display device 100 has a rectangular shape, h is a half value of a diagonal size of the image display device 100. f denotes a focal length of the eyepiece optical system 101.

[0107] In addition, the image magnification Mv is expressed by the following expression (A):

Mv=.omega.’(tan.sup.-1(h/L)) (A)

[0108] where

[0109] .omega.’ is a half value (rad) of a maximum field angle of view,

[0110] h is a maximum image height, and

[0111] L is a total length (a distance from the eye point E.P. to an image).

[0112] It is to be noted that the image refers to an image displayed on the image display device 100, for example. For example, in the case where the image display device 100 has the rectangular shape, h is the half value of the diagonal size of the image display device 100, as described above. L corresponds to the total length of the eyepiece optical system 101 described above (a distance from the eye point E.P. to a display surface of the image display device 100), for example.

[0113] In the head-mounted display having a high viewing angle with a field angle of view over 70.degree., using the image display device 100 having a small size relative to the diameter of the eyepiece optical system 101 as in the configuration example in FIG. 1 enables reduction in the total length and size of the eyepiece optical system 101 as compared with the case of using the image display device 100 having a large size. This is believed to contribute advantageously to a reduction in size of the head-mounted display. However, in a case of attempting to achieve such a head-mounted display using the coaxial eyepiece optical system 101, there is an issue of difficulty in increasing the image magnification Mv when attempting to increase an image-forming capability.

[0114] One of measures to improve the above issue is a method of using a plurality of glass materials having a high refractive index and high Abbe’s number as lenses that configure the eyepiece optical system 101. PTL 1 (Japanese Unexamined Patent Application Publication No. H11-23984) uses this method to thereby attain the eyepiece optical system 101 that achieves both high resolution and high magnification. However, this method involves using a glass lens having a high density, thus making the eyepiece optical system 101 heavy.

[0115] It is therefore desired to develop a display apparatus suitable for the head-mounted display, etc. that makes it possible to achieve a lighter weight and a wider angle of view and to provide high-definition beauty of an image.

1. Description of Display Apparatus According to Embodiment

[1.1. Overview of Display Apparatus According to Embodiment]

[0116] A display apparatus according to an embodiment of the present disclosure is applicable to the head-mounted display, for example.

[0117] FIGS. 4 and 5 each illustrate an overview of a display apparatus 1 according to an embodiment of the present disclosure. FIG. 4 illustrates a configuration of the display apparatus 1 in an x-z plane. FIG. 5 illustrates a configuration of the display apparatus 1 as viewed from a side surface (y-z plane).

[0118] As illustrated in FIGS. 4 and 5, the display apparatus 1 includes a left eyepiece display unit 102L and a right eyepiece display unit 102R arranged side by side at positions corresponding to locations of both eyes. The display apparatus 1 is configured to allow the image magnification My to be twice or more upon observation by both eyes.

[0119] Inside the left eyepiece display unit 102L, there are arranged a left-eye image display device 100L and a left eyepiece optical system 101L that guides a left-eye display image displayed on the left-eye image display device 100L to a left eye 2L.

[0120] Inside the right eyepiece display unit 102R, there are arranged a right-eye image display device 100R and a right eyepiece optical system 101R that guides a right-eye display image displayed on the right-eye image display device 100R to a right eye 2R.

[0121] Each of the left eyepiece optical system 101L and the right eyepiece optical system 101R is configured by an eyepiece including a plurality of single lenses. Each of the left eyepiece optical system 101L and the right eyepiece optical system 101R is a coaxial system, and is configured to allow the image magnification by each system (single eye) is twice or more.

[0122] In the left eyepiece optical system 101L and the right eyepiece optical system 101R, at least one of the plurality of single lenses is an aspherical lens including a resin material. Employing a resin material for at least one of the plurality of single lenses makes it possible to reduce weights of the left eyepiece optical system 101L and the right eyepiece optical system 101R. In addition, employing the aspherical lens for at least one of the plurality of single lenses makes it possible to suppress generation of aberration.

[0123] Each of the left-eye image display device 100L and the right-eye image display device 100R is configured by, for example, a flat-type small display panel such as an LCD and an organic EL display.

[0124] In a case where the display apparatus 1 is applied to a head-mounted display, or the like, usually, the same image is displayed, as a left-eye display image and a right-eye display image, in the left-eye image display device 100L and the right-eye image display device 100R, and the same image is observed in the left eye 2L and the right eye 2R. As a result, when viewed by both eyes, an image is observed at the same angle of view as the field angle of view in a single eye.

[0125] The left-eye image display device 100L displays, as the left-eye display image, an image for correction of distortion and chromatic aberration of magnification generated in the left eyepiece optical system 101L. Similarly, the right-eye image display device 100R displays, as the right-eye display image, an image for correction of distortion and chromatic aberration of magnification generated in the right eyepiece optical system 101R.

[0126] This enables the distortion and the chromatic aberration of magnification generated in the left eyepiece optical system 101L and the right eyepiece optical system 101R to be allowed to some extent, and enables the left eyepiece optical system 101L and the right eyepiece optical system 101R to substantially achieve high magnification and a reduction in weight of the optical system while maintaining an appearance not different from that in a case where the distortion and the chromatic aberration of magnification are not generated.

[1.2. Description of Correction of Distortion and Chromatic Aberration of Magnification]

[0127] In the following, description is given of specific examples of corrections of distortion and chromatic aberration of magnification by a left-eye display image and a right-eye display image displayed by the left-eye image display device 100L and the right-eye image display device 100R. The method for correction of the image displayed on the left-eye image display device 100L and the right-eye image display device 100R are substantially the same between the left and the right, and thus the left-eye image display device 100L or the right-eye image display device 100R is hereinafter referred to as the image display device 100 without distinction between the left and the right. Similarly, the left eyepiece optical system 101L or the right eyepiece optical system 101R is referred to as the eyepiece optical system 101 without distinction between the left and the right. Similarly, the left-eye display image or the right-eye display image is referred to as a display image without distinction between the left and the right. Further, similarly, also in other descriptions below, the descriptions are given as appropriate without distinction between the left and the right as needed.

(Correction of Distortion and Chromatic Aberration of Magnification)

[0128] FIG. 6 illustrates a correspondence relationship between an output image to the image display device 100 and an image actually visible through the eyepiece optical system 101 having distortion. FIG. 7 illustrates a correspondence relationship between an output image to the image display device 100 and an image actually visible through the eyepiece optical system 101 having chromatic aberration of magnification.

[0129] As illustrated in FIGS. 6 and 7, in a case where an image having been subjected to no correction processing is outputted to the image display device 100, an image actually visible through the eyepiece optical system 101 is distorted and has poor appearance due to distortion and chromatic aberration of magnification generated in the eyepiece optical system 101. In contrast, in a case where respective correction images corresponding to the distortion and the chromatic aberration of magnification generated in the eyepiece optical system 101 are outputted to the image display device 100, both aberrations are canceled out, resulting in a favorable appearance.

(Method of Correction of Distortion)

[0130] FIG. 8 illustrates an ideal light beam reaching position in the eyepiece optical system of a focal length f and a light beam reaching position (an actual light beam reaching position) distorted by generation of distortion. FIG. 9 schematically illustrates an ideal light beam reaching position and an actual light beam reaching position in a case where marginal light beams are aligned and an amount of deviation between the ideal light beam reaching position and the actual light beam reaching position. In FIG. 9, an ideal light beam reaching position of an angle .theta.a is set as r.sub.i,a; an ideal light beam reaching position of an angle .theta.b is set as r.sub.i,b; and an ideal light beam reaching position of an angle .theta.c is set as r.sub.i,c. In addition, an actual light beam reaching position of the angle .theta.a in a case where the distortion is generated is set as r.sub.r,a; an actual light beam reaching position of the angle .theta.b in the case where the distortion is generated is set as r.sub.r,b; and an actual light beam reaching position of the angle .theta.c in the case where the distortion is generated is set as r.sub.r,c. It is assumed here that .theta.a<.theta.b<.theta.c holds true and that the marginal light beam is a light beam of the angle .theta.c. In a case where the ideal light beam reaching position r.sub.i,c and the actual light beam reaching position r.sub.r,c of the marginal light beam are aligned (r.sub.i,c=r.sub.r,c), an amount of deviation between the light beam reaching positions of the angle .theta.a is r.sub.r,a-r.sub.i,a, and an amount of deviation between the light beam reaching positions of the angle .theta.b is r.sub.r,b-r.sub.i,b.

[0131] As illustrated in FIG. 8, a deviation is generated between the ideal light beam reaching position and the actual light beam reaching position at each angle. Description is given below of a method for eliminating the deviation and canceling out the generated distortion. First, as illustrated in FIG. 9, the ideal light beam reaching position r.sub.i,c and the actual light beam reaching position r.sub.r,c of the marginal light beam (light beam passing an outermost of the eyepiece optical system 101) are aligned. Next, an amount of deviation of the light beam reaching position at each of the angles is determined, and each determined amount of the deviation is reflected in the output image to the image display device 100. The above-described procedure enables formation of an image for correction of the distortion.

(Method of Correction of Chromatic Aberration of Magnification)

[0132] FIG. 10 illustrates ideal light beam reaching positions of light beams of respective colors outputted by the image display device 100 having a three-color (RGB) light source. FIG. 11 illustrates light beam reaching positions (actual light beam reaching positions) of respective colors varied due to generation of chromatic aberration of magnification.

[0133] In a case where there is chromatic aberration of magnification, as illustrated in FIG. 11, a deviation is generated in each of light beam reaching positions of RGB. In order to eliminate the deviation, a light beam reaching position for each of the colors at each angle is determined, and each determined light beam reaching position is reflected in an output image to the image display device 100, thereby enabling formation of an image for correction of chromatic aberration of magnification.

(Limit of Correction of Chromatic Aberration of Magnification)

[0134] FIG. 12 illustrates a green spectrum of a typical image display device 100. As illustrated in FIG. 12, the green spectrum of the typical image display device 100 has a center wavelength of 540 nm and a dispersion of 20 nm, for example. Here, a short-side wavelength (520 nm) with -20 nm relative to the center wavelength of 540 nm is set as .lamda.2, and a long-side wavelength (560 nm) with +20 nm relative to the center wavelength 540 nm is set as .lamda.1.

[0135] FIG. 13 illustrates a correlation between chromatic aberration of magnification (an amount of deviation between a center wavelength of a red color and a center wavelength of a blue color) generated in the eyepiece optical system 101 and an amount of deviation (r.lamda..sub.1-r.lamda..sub.2) between light beam reaching positions r.lamda..sub.1 and r.lamda..sub.2 of the long-side wavelength .lamda.1 (560 nm) of a green color and the short-side wavelength .lamda.2 (520 nm) of the green color in a case where only the green color is emitted.

[0136] As illustrated in FIG. 13, when the chromatic aberration of magnification generated in the eyepiece optical system 101 exceeds 600 .mu.m, the amount of deviation (r.lamda..sub.1-r.lamda..sub.2) between the light beam reaching positions of the long-side wavelength .lamda.1 of the green color and the short-side wavelength .lamda.2 of the green color exceeds 120 .mu.m. Thus, it is presumed that an image is blurred, causing a sense of discomfort in the appearance even in a case of observation at a single wavelength. This leads to an acceptable amount of chromatic aberration of magnification of 600 .mu.m.

2. Configuration Example and Workings and Effects of Eyepiece Optical System (Eyepiece)

[0137] Next, description is given of first and second configuration examples of the eyepiece that configures the left eyepiece optical system 101L and the right eyepiece optical system 101R in the display apparatus 1.

First Configuration Example

[0138] The configuration of an eyepiece according to the first configuration example corresponds to configurations of eyepieces (FIG. 15, etc.) according to Examples 1 to 9 described later. Each of the left eyepiece optical system 101L and the right eyepiece optical system 101R may be configured by an eyepiece of a three-group three-lens configuration in which a first lens L1, a second lens L2, and a third lens L3 are arranged as the plurality of single lenses in order from side of the eye point E.P. toward image side (side of the left-eye image display device 100L or side of the right-eye image display device 100R), as in the eyepieces (FIG. 15, etc.) according to Examples 1 to 9 described later.

[0139] In the above-described eyepiece (eyepiece according to the first configuration example) of the three-group three-lens configuration, the first lens L1 is preferably a spherical lens having a positive refractive power including a material of a refractive index of 1.439 or more with respect to a d-line. In addition, a lens surface of the first lens L1 on the side of the eye point E.P. preferably has a convex shape or a planar shape. Causing the first lens L1 to have a positive refractive power and the lens surface on the side of the eye point E.P. to have a convex shape or a planar shape makes it possible to suppress the maximal height of a marginal light beam. This allows for prospects of a reduction in capacitance of the optical system of each of the left eyepiece optical system 101L and the right eyepiece optical system 101R as well as a reduction in weight. In addition, using a spherical lens as the first lens L1 makes it possible to suppress manufacturing costs as compared with the case of using an aspherical lens.

[0140] In the eyepiece according to the first configuration example, the maximum amount of generation of the chromatic aberration of magnification is preferably 600 .mu.m or less. When the maximum amount of generation of the chromatic aberration of magnification exceeds 600 .mu.m, it becomes difficult to obtain a favorable image-forming capability. In addition, as illustrated in FIG. 13 mentioned above, in a case where the amount of generation of the chromatic aberration of magnification exceeds 600 .mu.m, even an output of a correction image to the image display device 100 causes a sense of discomfort in the appearance.

[0141] In addition, in the eyepiece according to the first configuration example, at least one of the second lens L2 or the third lens L3 is preferably an aspherical lens. Using the aspherical lens makes it possible to favorably correct aberration to be generated.

[0142] In addition, the eyepiece according to the first configuration example preferably satisfies the following conditional expression (1A):

0.450

where

[0143] f denotes an effective focal length, and

[0144] L’ denotes a distance from a lens surface on side closest to the eye point E.P. in the plurality of single lenses (first to third lenses L1 to L3) to an image (a display surface of the image display device 100).

[0145] Satisfying the conditional expression (1A) makes it possible to obtain favorable image-forming characteristics, while achieving a reduction in size of the optical system. When exceeding the upper limit of the conditional expression (1A), it becomes difficult to ensure a sufficient total length of the optical system with respect to the effective focal length f, thus causing a concern about possible deterioration of resolution, field curvature, and distortion of a peripheral part when attempting to achieve an optical system having a predetermined image magnification. When falling below the lower limit of the conditional expression (1A), the total length of the optical system becomes too long for the effective focal length f, thus increasing a volume of the optical system when attempting to achieve an optical system having a predetermined image magnification. This causes a concern about possible prevention of a reduction in size of the entire display apparatus 1.

[0146] In addition, the eyepiece according to the first configuration example preferably satisfies the following conditional expression (2A):

0.400

where

[0147] t’ denotes a summation of respective center thicknesses of the plurality of single lenses (first to third lenses L1 to L3), and

[0148] L’ denotes a distance from a lens surface on side closest to the eye point E.P. in the plurality of single lenses (first to third lenses L1 to L3) to an image (a display surface of the image display device 100).

[0149] In a head-mounted display having a high viewing angle, a pupil position shifts when observing a peripheral region of an image (hereinafter, referred to as “eye shift”). Satisfying the conditional expression (2A) makes it possible to ensure a sufficient lens thickness and to achieve robust characteristics against the eye shift. When falling below the lower limit of the conditional expression (2A), it becomes difficult to ensure a sufficient lens thickness, thus leading to a concern that the robustness against the eye shift may be lost.

Second Configuration Example

[0150] A configuration of an eyepiece according to the second configuration example corresponds to configurations of eyepieces (FIG. 51, etc.) according to Examples 10 to 18 described later. Each of the left eyepiece optical system 101L and the right eyepiece optical system 101R may be configured by an eyepiece of a four-group four-lens configuration in which the first lens L1, the second lens L2, the third lens L3, and a fourth lens L3 are arranged as a plurality of single lenses in order from the side of the eye point E.P. toward the image side (side of the left-eye image display device 100L or side of the right-eye image display device 100R), as in the eyepieces (FIG. 51, etc.) according to Examples 10 to 18 described later.

[0151] In the above-described eyepiece (eyepiece according to the second configuration example) of the four-group four-lens configuration, the first lens L1 is preferably a spherical lens having a positive refractive power including a material of a refractive index of 1.439 or more with respect to a d-line. In addition, the lens surface of the first lens L1 on the side of the eye point E.P. preferably has a convex shape or a planar shape. Causing the first lens L1 to have a positive refractive power and the lens surface on the side of the eye point E.P. to have a convex shape or a planar shape makes it possible to suppress the maximal height of a marginal light beam. This allows for prospects of a reduction in capacitance of the optical system of each of the left eyepiece optical system 101L and the right eyepiece optical system 101R as well as a reduction in weight. In addition, using a spherical lens as the first lens L1 makes it possible to suppress manufacturing costs as compared with the case of using an aspherical lens.

[0152] In the eyepiece according to the second configuration example, the maximum amount of generation of the chromatic aberration of magnification is preferably 600 .mu.m or less. When the maximum amount of generation of the chromatic aberration of magnification exceeds 600 .mu.m, it becomes difficult to obtain a favorable image-forming capability. In addition, as illustrated in FIG. 13 mentioned above, in a case where the amount of generation of the chromatic aberration of magnification exceeds 600 .mu.m, even an output of a correction image to the image display device 100 causes a sense of discomfort in the appearance.

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