JP2000019451A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact video display device in which space for arranging a projection optical system and the like is easily secured. SOLUTION: An eyepiece optical system EL projecting a two-dimensional video on an image field I to the eye so that the enlarged virtual image thereof may be observed, is constituted of a common use optical system CL whose one part constitutes one part of the projection optical system. The projection optical system projects the two-dimensional video to the image field I. The optical axis A1 of the optical system EL is eccentric to the visual line A0 of the eye, and the optical system CL has an anamorphic aspherical surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device, and more particularly to a video display device for displaying images on a liquid crystal display.
The present invention relates to an image display device such as an HMD (head mounted display) for projecting a two-dimensional image to an eye with an eyepiece optical system and observing an enlarged virtual image.

[0002]

2. Description of the Related Art Various types of image display devices have been proposed as image display devices for displaying an enlarged virtual image of a two-dimensional image displayed on a display unit by an eyepiece optical system. For example, a type using a transmissive liquid crystal display or a transmissive screen as a display unit is known.

[0003]

In the type using the transmission type liquid crystal display, it is difficult to increase the density of the transmission type liquid crystal, so that a wide viewing angle and a high definition image display cannot be achieved. Further, a space for arranging an illumination optical system for illuminating the liquid crystal is required, so that it is difficult to make the liquid crystal compact. On the other hand, in the type using the transmission screen, a high-definition image can be projected on the transmission screen, so that a wide viewing angle and high-definition image display can be achieved. However, since it is necessary to arrange the light source, the projection optical system, the transmission screen, and the eyepiece optical system, the overall length becomes long, and it is more difficult to achieve compactness.

The present invention has been made in view of such circumstances, and has as its object to provide a compact video display device.

[0005]

In order to achieve the above object, an image display apparatus according to a first aspect of the present invention includes a display unit for displaying a two-dimensional image, and an enlarged virtual image obtained by projecting the two-dimensional image onto an eye. And an eyepiece optical system for observing the eyepiece, wherein the optical axis of the eyepiece optical system is decentered with respect to the visual axis of the eye.

According to a second aspect of the present invention, in the image display apparatus according to the first aspect, the display section is formed of a reflective screen or a reflective two-dimensional display element.

According to a third aspect of the present invention, in the image display apparatus according to the first aspect, the display unit displays the two-dimensional image on a curved surface.

A video display apparatus according to a fourth aspect of the present invention is the image display apparatus according to the second aspect of the present invention, further comprising a projection optical system for projecting an image on the reflective screen or an illumination for illuminating the reflective two-dimensional display element. An optical system is provided, and at least a part of the eyepiece optical system is a shared optical system forming at least a part of the projection optical system or the illumination optical system.

According to a fifth aspect of the present invention, in the image display apparatus according to the fourth aspect, the common optical system has at least one rotationally asymmetric optical surface, and the optical surface has a surface shape of: A plane including the optical axis of the shared optical system and the visual axis of the eye is defined as a first symmetry plane, and the first axis is defined on the optical axis of the shared optical system.
Is characterized by having a plane orthogonal to the plane of symmetry as a second plane of symmetry.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video display device embodying the present invention will be described with reference to the drawings. Note that X, Y,
Z indicates directions orthogonal to each other, and the direction perpendicular to the pupil (E1 or E2) is defined as the Z direction. In addition, the same portions or corresponding portions in the embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

FIG. 1, FIG. 3, and FIG. 5 are optical configuration diagrams corresponding to eyepiece optical systems (EL) constituting the first, second, and third embodiments, respectively. {Eyepiece optical system (EL)
Exit pupil. }. FIG. 2, FIG. 4 and FIG.
The projection optical system (P which constitutes the first, second and third embodiments)
FIG. 3 is an optical configuration diagram corresponding to L), and E2 is a pupil (an entrance pupil corresponding to a scanning deflection surface) of the projection optical system (PL).
In the optical configuration diagram, I is an image plane, and this image plane (I) corresponds to a display surface of a display unit (for example, a reflective screen or a reflective two-dimensional display element) that displays a two-dimensional image. Also, Si (i = 1,
(2,3, ...) is the i-th surface counted from the pupil (E1 or E2) side in the system including the pupil (E1 or E2) and the image plane (I). The marked surface is an aspherical surface, and the surface marked with # is an anamorphic aspherical surface.

In each of the embodiments, a reflective screen as a display unit for displaying a two-dimensional image, an eyepiece optical system (EL) for projecting the two-dimensional image to the eye and observing an enlarged virtual image thereof, and a reflective screen A projection optical system (PL) that projects images to
It has. In any of the embodiments, at least a part of the eyepiece optical system (EL) is a projection optical system (PL).
Is a shared optical system (CL) that constitutes at least a part of.
That is, in the first embodiment, a part of the eyepiece optical system (EL) and a part of the projection optical system (PL) are constituted by the shared optical system (CL). In the embodiment, both the eyepiece optical system (EL) and the projection optical system (PL) are constituted only by the shared optical system (CL). Note that, in each optical system (EL, PL) of the first embodiment, the optical elements except for the shared optical system (CL) are
(L, PL).

In the first and third embodiments, since the image plane (I) forms a curved surface, a reflection type screen is suitable as a display unit. On the other hand, when the image plane (I) forms a plane as in the second embodiment, a reflective two-dimensional display element is preferable as the display unit. As described above, it is desirable that the display unit that displays a two-dimensional image is formed of a reflective screen or a reflective two-dimensional display element. By using a reflective display unit, it is not necessary to arrange a light source or an optical member on the back surface side of the display unit. Therefore, it is possible to shorten the overall length of the entire device and to achieve higher definition image display than when a transmissive liquid crystal display is used.

In any of the embodiments, the display section can be constituted by a reflective screen or a reflective two-dimensional display element. However, when a reflective two-dimensional display element is used as the display section, the reflective two-dimensional display element is used. A projection optical system (PL) can be used as an illumination optical system for illuminating the display element. The pupil (E2) of the projection optical system (PL) is an entrance pupil corresponding to a deflection surface for scanning.When the projection optical system (PL) is used as an illumination optical system, the position of the pupil (E2) is Light source position.

An image display apparatus having a projection optical system (PL) for projecting an image on a reflective screen as in each embodiment, or an image display having an illumination optical system for illuminating a reflective two-dimensional display element. In the apparatus, it is desirable that at least a part of the eyepiece optical system (EL) is a projection optical system (PL) or a shared optical system (CL) that forms at least a part of an illumination optical system. With such a configuration, the optical path of the eyepiece optical system (EL) and the optical path of the projection optical system (PL) or the illumination optical system can be overlapped, so that the viewing angle is widened and the overall length of the optical system is increased. It becomes possible to make it compact. Further, since at least a part of the optical system (EL, PL) is constituted by the shared optical system (CL), the cost can be reduced accordingly.

As in the first and third embodiments, it is preferable that the display unit displays a two-dimensional image on a curved surface. If it is configured to display a two-dimensional image on a curved surface,
The image plane (I) can be curved in accordance with the curvature of field of the eyepiece optical system (EL) and the projection optical system (PL). Therefore, the configuration of the optical system can be simplified, and
A wide viewing angle can be achieved. The eyepiece optical system (E
When L) is composed of a refractive lens, the first, third
It is more desirable to configure the display unit such that the two-dimensional image has a concave shape toward the pupil (E1) as in the embodiment. With such a configuration, it is possible to correct the field curvature caused by the positive refractive lens on the display unit.
Therefore, the configuration of the optical system can be simplified, and a wide viewing angle can be achieved.

In each of the embodiments, the optical axis (A) of the eyepiece optical system (EL)
1) is eccentric with respect to the visual axis (A0) of the eye. With such a configuration, it is easy to secure a space for disposing the projection optical system (PL) and the illumination optical system. Therefore, the pupil (E1)
It is possible to arrange a projection optical system (PL) and an illumination optical system on the same side as the above, and it is possible to achieve a compact image display device.

In each of the embodiments, the shared optical system (CL) has at least one rotationally asymmetric optical surface (ie, an anamorphic aspheric surface). The surface shape of the optical surface is such that a plane including the optical axis (A1) of the shared optical system (CL) and the visual axis (A0) of the eye is the first symmetry plane, and is located on the optical axis (A1) of the shared optical system. Has a symmetry that a plane orthogonal to the first symmetry plane is a second symmetry plane. Although the optical axis (A1) of the shared optical system (CL) in each embodiment coincides with the optical axis of the eyepiece optical system (EL), in the first embodiment, the optical axis (A1) Since the portion excluding the shared optical system (CL) is decentered parallel to the optical axis (A1) of the shared optical system (CL), the optical axis of that portion is shown as A2 in FIG.

As described above, the common optical system (CL) has at least one optical surface having a rotationally asymmetric surface shape, and the surface shape of the optical surface is different from the optical axis of the common optical system (CL) and the eye. A plane including the visual axis (A0) is defined as a first symmetry plane, and the optical axis (A
1) It is desirable to have a symmetry in which a plane orthogonal to the first symmetry plane is set as a second symmetry plane. With such a configuration, symmetrical aberration characteristics can be obtained on both sides of the first symmetry plane, and the image performance naturally changes from the center of the observer's field of view to both sides with respect to the first symmetry plane. be able to. The pupil of the observer (E1) centered on the second plane of symmetry
Symmetric aberration performance can be obtained on the pupil (E2) side of the projection optical system (PL). Therefore, both optical systems (EL, PL)
(Ie, configuring a shared optical system (CL)) becomes easy. Further, it is possible to easily correct the asymmetric aberration caused by decentering the optical axis (A1) with respect to the visual axis (A0) by using the rotationally asymmetric surface that maintains the above-mentioned respective symmetries.

The projection display of a two-dimensional image by the projection optical system (PL) is desirably performed by mirror scanning. With a configuration in which projection display is performed by mirror scanning, a configuration in which a parallel light source and a scanning mirror are combined with a projection optical system (PL) can be achieved, so that downsizing can be achieved. Furthermore, the optical path length from the scanning mirror to the reflective screen is
It is desirable that the length be longer than the optical path length from the pupil (E2) to the reflective screen. With this configuration, it is possible to obtain a viewing angle equal to or larger than the swing angle of the light beam scanned by the scanning mirror. Therefore, since it becomes possible to reduce the swing angle of the scanning mirror and to speed up the scanning,
A wider viewing angle and higher definition image display are possible. Further, it is desirable that the scanning light beam diameter be smaller than the pupil diameter of the eyepiece optical system (EL). In order to obtain a necessary pupil diameter, a configuration may be adopted in which the light flux is widened using the diffusivity of the reflective screen. As a result, the diameter of the scanning mirror can be reduced, so that high-speed scanning can be performed, and a wider viewing angle and higher definition image display can be performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an image display apparatus embodying the present invention will be described in more detail with reference to construction data of an eyepiece optical system (EL) and a projection optical system (PL), a spot diagram, and the like. Examples 1 to 3 given here as examples
Correspond to the first to third embodiments described above, respectively, and each of the eyepiece optical system (EL) and the projection optical system (P
Optical configuration diagrams (L) (FIGS. 1 to 6) showing L) respectively show the optical configurations of the corresponding embodiments. 7 to 12
The spot diagrams of the eyepiece optical systems of Examples 1 to 3
(EL) and the imaging characteristics of the projection optical system (PL) are shown.

The eyepiece optical system (EL) and the projection optical system (P
In the construction data of (L), Si (i = 1,2,
3, ...) is the i-th surface counted from the pupil (E1 or E2) side in a system including the pupil (E1 or E2) and the image plane (I), and ri (i =
1,2,3, ...) are the radii of curvature of the surface Si. Di (i = 1,2,
(3, ...) indicates the i-th axial top surface interval counted from the pupil (E1 or E2) side in the system including the pupil (E1 or E2) and the image plane (I), and Ni (i = 1,2,3, ...), νi (i = 1,2,3, ...) is the pupil (E1
Or, the refractive index (Nd) and Abbe number (νd) of the i-th optical element with respect to the d-line counted from the E2) side are shown.

In the rectangular coordinates (X, Y, Z), the pupil (E1 or E1)
The vertex coordinates (XDE, YDE, ZDE) = (XD) with the Z-direction perpendicular to 2) and the center position of the pupil (E1 or E2) as the origin (0,0,0)
Parallel eccentric position in the Y direction, parallel eccentric position in the Y direction, and parallel eccentric position in the Z direction. Note that the diameter and the viewing angle of the pupil (E1) or the diameter and the projection angle of the pupil (E2) are shown together with other data, and the eyepiece optical system (EL) and the projection optical system (PL) are shared optical system ( In the case where the data is composed only of CL), common data will be omitted.

A surface marked with an asterisk (*) on the surface Si indicates that the surface is constituted by an aspheric surface, and is defined by the following equation (AS) representing the surface shape of the aspheric surface (based on each surface vertex). Shall be.
Further, the surface marked with a # mark on the surface Si indicates that the surface is constituted by an anamorphic aspheric surface, and the following expression representing the surface shape of the anamorphic aspheric surface (each surface vertex reference) ( AN)
Shall be defined as Each aspherical surface data and anamorphic aspherical surface data are shown together with other data. Z = (c · h ² ) / [1 + √ {1- (1 + K) · c ² · h ² }] + (A · h ⁴ + B · h ⁶ + C · h ⁸ + D · h ¹⁰ )… (AS) Z = (CUX · X ² + CUY · Y ² ) / [1 + √ {1- (1 + KX) · CUX ² · X ^2- (1 + KY) · CUY ² · Y ² } ] + AR {(1-AP) ・ X ² + (1 + AP) ・ Y ² } ² + BR {(1-BP) ・ X ² + (1 + BP) ・ Y ² } ³ + CR {(1 -CP) ・ X ² + (1 + CP) ・ Y ² } ⁴ + DR {(1-DP) ・ X ² + (1 + DP) ・ Y ² } ⁵ … (AN) where the expressions (AS), ( AN), Z: Displacement from the reference plane in the optical axis direction, h: Height in the direction perpendicular to the optical axis, c: Paraxial curvature, K, A, B, C, D: Aspherical coefficient KY, KX, RY, RX, AR, BR, CR, DR, AP, BP, CP, DP: Anamorphic aspherical coefficients, CUY = 1 / RY, CUX = 1 / RX.

[0025]

[Anamorphic Aspherical Data of Second Surface (S2)] KY = -4.590, KX = -3.499, RX = 26.688 AR = 0.8827 × 10 ^-7 , BR = -0.2333 × 10 ^-7 , CR = 0.5703 × 10 ^-10 ,
DR = -0.3919 × 10 ^-13 AP = -2.578, BP = 0.07136, CP = 0.01293, DP = -0.05008

[Anamorphic aspherical data of the fourth surface (S4)] KY = -28.658, KX = -139.600, RX = 128.182 AR = 0.3236 × 10 ^-4 , BR = -0.3124 × 10 ^-7 , CR = 0.1510 × 10 ^-10 ,
DR = 0.1994 × 10 ^-14 AP = 0.003902, BP = 0.04664, CP = 0.03435, DP = 0.09920

[Anamorphic aspherical data of the fifth surface (S5)] KY = -4.261 × 10 ⁷ , KX = -4.261 × 10 ⁷ , RX = 0.016897 AR = 0.1830 × 10 ^-4 , BR = -0.4299 × 10 ^-7 , CR = 0.5337 × 10 ^-10 ,
DR = -0.2492 × 10 ^-13 AP = -0.1803, BP = 0.03497, CP = 0.05517, DP = 0.02056

[Anamorphic aspheric surface data of the eighth surface (S8)] KY = -45.633, KX = -28.118, RX = -29.738 AR = -0.3973 × 10 ^-4 , BR = 0.6667 × 10 ^-7 , CR = 0.2597 × 10 ^-9 , D
R = -0.3704 × 10 ^-12 AP = 0.02176, BP = 0.2600, CP =
0.004092, DP = 0.711

[0030]

[Anamorphic aspherical data of the second surface (S2)] KY = -6.774, KX = -5.007, RX = 16.489 AR = 0.1439 × 10 ^-4 , BR = -0.8091 × 10 ^-8 , CR = -0.6594 × 1
0 ^-11 , DR = 0.6299 × 10 ^-14 AP = 0.2091, BP = 0.2388, CP = 0.1225, DP = 0.1934

[Anamorphic aspherical data of the fourth surface (S4)] KY = -4.590, KX = 0.1227, RX = 58.134 AR = 0.1389 × 10 ^-4 , BR = -0.1615 × 10 ^-7 , CR = 0.2534 × 10 ^-10 ,
DR = -0.1162 × 10 ^-13 AP = -0.7779, BP = -0.5058, CP = 0.007286, DP = 0.04087

[Anamorphic aspherical data of the sixth surface (S6)] KY = -28.658, KX = -139.600, RX = 128.182 AR = 0.3236 × 10 ^-4 , BR = -0.3124 × 10 ^-7 , CR = 0.1510 × 10 ^-10 ,
DR = 0.1994 × 10 ^-14 AP = 0.003902, BP = 0.04664, CP = 0.03435, DP = 0.09920

[Anamorphic aspherical data of the seventh surface (S7)] KY = -4.261 × 10 ⁷ , KX = -4.261 × 10 ⁷ , RX = 0.016897 AR = 0.1830 × 10 ^-4 , BR = -0.4299 × 10 ^-7 , CR = 0.5337 × 10 ^-10 ,
DR = -0.2492 × 10 ^-13 AP = -0.1803, BP = 0.03497, CP = 0.05517, DP = 0.02056

[Anamorphic aspherical data of the tenth surface (S10)] KY = -45.633, KX = -28.118, RX = -29.738 AR = -0.3973 × 10 ^-4 , BR = 0.6667 × 10 ^-7 , CR = 0.2597 × 10 ^-9 , D
R = -0.3704 × 10 ^-12 AP = 0.02176, BP = 0.2600, CP = 0.004092, DP = 0.1711

[0036]

[Aspherical surface data of second surface (S2)] K = -0.4557 A = -0.1789 × 10 ^-5 B = -0.5019 × 10 ^-7 C = 0.6971 × 10 ^-10 D = -0.2216 × 10 ^-13

[Aspherical surface data of fourth surface (S4)] K = 1.611 × 10 ⁵ A = 0.3867 × 10 ^-4 B = -0.3707 × 10 ^-7 C = 0.2498 × 10 ^-10 D = -0.2251 × 10 ^{− 13}

[Aspherical surface data of fifth surface (S5)] K = -4.261 × 10 ⁷ A = 0.4583 × 10 ^-4 B = -0.8942 × 10 ^-7 C = 0.7670 × 10 ^-10 D = -0.3552 × 10 ^-13

[Aspherical surface data of the eighth surface (S8)] K = -9.259 A = -0.1544 × 10 ^-4 B = 0.2483 × 10 ^-7 C = -0.6585 × 10 ^-11 D = 0.1234 × 10 ^-13

<< Projection Optical System (PL) of Embodiment 2 >> Pupil diameter (mm) = φ2.0 Projection angle (°): 40 (X direction) × 50 (Y direction) S2: YDE = 13.0

[0042]

[Aspherical surface data of second surface (S2)] K = -0.5817 A = -0.7293 × 10 ^-6 B = -0.1681 × 10 ^-7 C = 0.2310 × 10 ^-10 D = -0.8658 × 10 ^-14

[Aspherical surface data of third surface (S3)] K = -1.985 × 10 ⁷ A = 0.6040 × 10 ^-5 B = -0.5066 × 10 ^-7 C = 0.1047 × 10 ^-9 D = -0.6469 × 10 ^-13

[Aspherical surface data of sixth surface (S6)] K = -0.08732 A = 0.18511 × 10 ^-4 B = 0.7834 × 10 ^-7 C = -0.4007 × 10 ^-9 D = 0.1891 × 10 ^-12

<< Projection Optical System (PL) of Embodiment 3 >> Pupil diameter (mm) = φ2.0 Projection angle (°): 20 (X direction) × 40 (Y direction) S2: YDE = 12.0

[0047]

As described above, according to the first to fifth aspects, since the optical axis of the eyepiece optical system is decentered with respect to the visual axis of the eye, the projection optical system and the like are arranged. It is easy to secure a space for the operation. Therefore, the size of the image display device can be reduced.

According to the second, fourth, and fifth aspects of the present invention, further compactness and high-definition image display can be achieved by the reflective display unit. According to the third aspect, since the image surface can be curved in accordance with the field curvature aberration of the eyepiece optical system or the like, the configuration of the optical system can be simplified and a wide viewing angle can be achieved. Can be. According to the fourth aspect, since the optical path of the eyepiece optical system and the optical path of the projection optical system or the illumination optical system can be overlapped, the viewing angle is widened, the overall length of the optical system is made compact, and the cost is reduced. It is possible to do. According to the fifth aspect, it is easy to configure the shared optical system, and it is easy to correct asymmetric aberration.

[Brief description of the drawings]

FIG. 1 is an optical configuration diagram showing an eyepiece optical system and an optical path constituting a first embodiment (Example 1).

FIG. 2 is an optical configuration diagram showing a projection optical system and an optical path constituting the first embodiment (Example 1).

FIG. 3 is an optical configuration diagram showing an eyepiece optical system and an optical path constituting a second embodiment (Example 2).

FIG. 4 is an optical configuration diagram showing a projection optical system and an optical path constituting a second embodiment (Example 2).

FIG. 5 is an optical configuration diagram showing an eyepiece optical system and an optical path constituting a third embodiment (Example 3).

FIG. 6 is an optical configuration diagram showing a projection optical system and an optical path constituting a third embodiment (Example 3).

FIG. 7 is a spot diagram of an eyepiece optical system constituting the first embodiment.

FIG. 8 is a spot diagram of the projection optical system constituting the first embodiment.

FIG. 9 is a spot diagram of the eyepiece optical system that constitutes the second embodiment.

FIG. 10 is a spot diagram of a projection optical system constituting the second embodiment.

FIG. 11 is a spot diagram of an eyepiece optical system according to a third embodiment.

FIG. 12 is a spot diagram of a projection optical system constituting the third embodiment.

[Explanation of symbols]

 EL… ocular optical system PL… projection optical system CL… shared optical system A0… visual axis A1… optical axis E1… pupil E2… pupil I… image plane (two-dimensional image)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/64 511 H04N 5/64 511A F term (Reference) 2H087 KA00 KA06 KA14 LA01 LA12 PA02 PA03 PA04 PA18 PB03 PB04 PB05 QA02 QA07 QA14 QA22 QA25 QA32 QA34 QA41 QA42 QA45 QA46 RA05 RA06 RA12 RA13 2H088 EA10

Claims (5)

[Claims] A display unit for displaying a two-dimensional image;
An eyepiece optical system for projecting a two-dimensional image onto the eye and observing an enlarged virtual image thereof, wherein the optical axis of the eyepiece optical system is eccentric with respect to the visual axis of the eye. Video display device. 2. The video display device according to claim 1, wherein said display unit comprises a reflective screen or a reflective two-dimensional display element. 3. The image display device according to claim 1, wherein the display unit displays the two-dimensional image on a curved surface. 4. A projection optical system for projecting an image on the reflection type screen, or an illumination optical system for illuminating the reflection type two-dimensional display element, wherein at least a part of the eyepiece optical system is the projection optical system. 3. The image display device according to claim 2, wherein the image display device is a shared optical system forming at least a part of a system or an illumination optical system. 5. The common optical system has at least one optical surface having a rotationally asymmetric surface shape, and the surface shape of the optical surface is:
A plane including the optical axis of the shared optical system and the visual axis of the eye is defined as a first symmetry plane, and a plane orthogonal to the first symmetry plane on the optical axis of the shared optical system is defined as a second symmetry plane. The video display device according to claim 4, wherein the video display device has a symmetry.