JPH09166760A - Picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture display device capable of observing a picture display element in wide field angle and high resolution states through the device is compact and light and observing an external image by simple operation without using a specific optical element other than optical elements of an eyepiece optical system. SOLUTION: The eyepiece optical system 3 has at least three optical faces 11, 13, 14 to form a prism body having at least one reflection surface 12 having positive power placed eccentrically or inclined to an observer's visual axis 2 and space formed by at least three faces 11, 13, 14 is filled with a medium which has refractive index larger than '1'. The prism body is constituted so as to be rotated or moved between a 1st arrangement position for guiding a light beam generated from a picture display element 4 to an observer's eyeball 1 and a 2nd arrangement position for passing a light beam from the outside and guiding the beam to the eyeball 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly, to a head- or face-mounted image display device that is small and lightweight, but can observe an image with a wide angle of view and high resolution.

[0002]

2. Description of the Related Art In recent years, a helmet-type or goggle-type head- or face-mounted image display device has been developed for the purpose of enjoying a large-screen image for virtual reality or personally. This type of image display device needs to be mounted on the head for observation. Therefore, in order to minimize the physical burden on the observer, it is important to be small and lightweight. On the other hand, the larger the viewing angle of view, the larger the screen to be observed, and the observer can be given a strong sense of presence and immersion. Therefore,
A wide angle of view to be presented is an important condition of the image display device.

Further, when the head or face-mounted image display device is used as a terminal which is an output device of a computer and a peripheral device such as a keyboard or a mouse is operated, or the head or face-mounted image display device is displayed. When an emergency occurs in the surroundings while the device is being used as a display device of a game machine, it is necessary to let an observer recognize the outside world by controlling with a signal from the outside or operating a switch or the like.

As a conventional image display device for observing an external image through the image display device, for example, Japanese Patent Application No. 3-10170.
There is a No. 9. This is to arrange an optical layer that cancels the power of the eyepiece optical system on the side opposite to the observer of the eyepiece optical system and guide the light flux from the outside to the observer's eyeball so that the outside image can be observed. Is.

[0005]

However, according to Japanese Patent Application No. 3-101709, since another optical element is arranged outside the eyepiece optical system, it is projected from the face when it is worn on the head. The amount becomes large, the balance of the entire apparatus becomes unbalanced, and the weight also increases. Therefore, the physical burden on the observer has increased.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to observe an image display element with a wide angle of view and high resolution while being compact and lightweight, and further, an eyepiece optical system. It is an object of the present invention to provide an image display device suitable for a head-mounted image display device capable of observing an external image by a simple operation without using a special optical element other than the optical element.

[0007]

An image display apparatus according to the present invention that achieves the above object has an image display element for displaying an image,
In an image display device comprising an eyepiece optical system that projects an image formed by the image display element and guides it to an observer's eyeball, the eyepiece optical system has at least three optical surfaces, and the at least three surfaces. The space formed by is composed of a prism body having a reflecting surface having at least one positive power, which is filled with a medium having a refractive index larger than 1 and is eccentric or inclined with respect to the observer's visual axis,
The prism body is between a first arrangement position for guiding the light beam emitted from the image display element to the observer's eyeball and a second arrangement position for allowing the light beam from the outside to pass and leading to the observer's eyeball. It is characterized in that it can be rotated or moved by.

In this case, among the surfaces forming the prism body,
In the second arrangement position, it is desirable that the two opposing surfaces have substantially zero power with respect to the light flux from the outside world that passes through the two surfaces.

Further, at the first arrangement position, when the light flux emitted from the image display element is internally reflected by the prism body,
It is desirable to be configured to satisfy the condition of total reflection.

Hereinafter, the reason and operation of adopting the above structure in the present invention will be described. In an image display device comprising an image display element for displaying an image and an eyepiece optical system for projecting an image formed by the image display element to an observer's eyeball, the eyepiece optical system has at least three optical surfaces. And having at least one reflecting surface having a positive power, which is filled with a medium having a refractive index larger than 1 and is eccentric or inclined with respect to the observer's visual axis. And a second arrangement position that guides the light flux emitted from the image display element to the observer's eyeball and a second arrangement position that guides the light flux from the outside to the observer's eyeball. It is possible to observe the electronic image and the external image without using a special optical element by arranging the optical element so that the electronic image and the external image can be rotated or moved.

Hereinafter, description will be made with reference to FIGS. 1 and 2. FIG. 1A is a side view of the image display device of the present invention. FIG. 1B is a perspective view of the image display device of the present invention viewed from the observer side. FIG. 2A is a side view when the image display device of the present invention is rotated and moved. FIG. 2 (b)
FIG. 4 is a perspective view seen from the observer side when the image display device of the present invention is rotated and moved. 1 to 2, 1
Is the observer's pupil position, 2 is the observer's visual axis, 3 is the eyepiece optical system,
Reference numeral 4 is an image display element, 5 is a light blocking means, 11 is the first surface of the eyepiece optical system, 12 is its second surface, 13 is its third surface, and 14 is its fourth surface.

When observing the image of the image display element 4 in the state shown in FIG. 1, the light ray emitted from the image display element 4 passes through the fourth surface 14 of the eyepiece optical system 3 Surface 13,
The light is internally reflected on the second surface 12, passes through the first surface 11, and enters the observer's eyeball with the observer pupil 1 as an exit pupil. In the image display device of the present invention, the eyepiece optical system 3 is at least 1 which is eccentric or inclined with respect to the observer's visual axis 2.
Since it is a prism body having a reflecting surface with two positive powers, it is similar in operation to a concave mirror. In general,
The concave mirror produces less aberration than the eyepiece optical system using a lens. At the same time, since the light rays are folded along the shape of the face, a small size and light weight can be realized. Therefore, it is possible to provide a clear observation image with less physical burden on the observer.

The eyepiece optical system 3 is moved and rotated to the state shown in FIG. 2 so that the third surface 13 of the eyepiece optical system 3 is brought close to the observer's eye, and the second surface 12 facing the observer's eyeball is further provided. It is arranged on the side opposite to the eyeball so that each surface is substantially perpendicular to the observer's visual axis 2. The light path from the outside in this state enters the second surface 12, passes through the third surface 13, and enters the observer's eyeball with the observer pupil 1 as the exit pupil. This makes it possible to observe the external image.

In the above structure, the prism body constituting the eyepiece optical system 3 has four optical surfaces and the space formed by these surfaces is filled with a medium having a refractive index larger than 1. However, it is possible to configure the optical surface to be three, and of course, it is possible to configure five or more.

In the state of observing the outside world in FIG. 2, the combined power (refractive power) of the second surface 12 and the third surface 13, which are the two surfaces that face each other and constitute the eyepiece optical system 3, becomes substantially zero. Is desirable. With such a configuration, since the light flux from the outside world is incident on the observer's pupil 1 as a substantially parallel light flux, a clear outside world image can be observed.

In the state of FIG. 1, assuming that the light flux emitted from the image display element 4 does not satisfy the condition of total internal reflection of the eyepiece optical system 3, in order to observe an electronic image, FIG. As is clear from a), the second surface 1
It is necessary to apply a mirror coat to the second and third surfaces 13.

On the other hand, when observing the external image, the eyepiece optical system 3 is rotated and moved to move the second surface 1 as shown in FIG.
Although the 2nd and 3rd surface 13 is arrange | positioned facing an observer in the substantially parallel state, the 2nd surface 12 and the 3rd surface 13 must transmit external light. Therefore, when there is a demand for selectively observing the electronic image and the external image, the second surface 12 and the third surface 13 need to be half-mirror coated. However, this reduces the light amount of both the image of the image display element 4 and the external image to about 1/4. In addition, since the half mirror coat is usually a multi-layer film, the manufacturing cost is high and the manufacturing process becomes long.

By the way, if the internal reflection surface of the prism body which is the eyepiece optical system 3 satisfies the total reflection condition, all the light rays emitted from the image display element 4 are totally reflected, so that a bright image can be observed. Since the electron image and the external image can be switched and observed without applying a mirror coat or a half mirror coat, the cost is greatly reduced and the manufacturing process can be simplified.

If the image display element 4 and the eyepiece optical system 3 can be rotated or moved at the same time, the so-called superimpose can observe the images simultaneously by matching the exit pupils of the electronic image and the external image. Is possible.

Further, it is important to dispose the light-shielding means 5 such as a liquid crystal shutter on the outside of the surface of the eyepiece optical system 3 opposite to the observer in order to switch between the external image and the electronic image. If the external image is not desired to be observed, unless the external light is made incident on the eyepiece optical system 3 by the light shielding means 8, the external light may be incident on the eyeball at any time. The image cannot be observed. On the contrary, when it is desired to observe only the external image, it can be realized by setting the state shown in FIG. 2 and not displaying the image on the image display element 4 and setting the light shielding means 8 in the transmission mode.

Further, at least one constituting the prism body
It is effective for aberration correction that the reflecting surface having two positive powers, that is, the second surface 12 in FIGS. 1 and 2 is an aspherical surface. This is an important condition for correcting coma aberration, especially high-order coma aberration and coma flare, which are generated on the reflecting surface which is decentered or arranged at an inclination from the visual axis.

As in the present invention, in an image display device using an eyepiece optical system of a type having a reflecting surface which is decentered or inclined in front of the observer's eyeball, the light rays incident on the reflecting surface are oblique even on the axis. Therefore, complicated coma is generated on the central axis of the reflecting mirror. This complicated coma aberration increases as the inclination angle of the reflection surface increases. However, in order to realize a small-sized image display device having a wide angle of view, it is difficult to secure a wide-angle observation image because the image display element and the optical path interfere with each other unless the eccentricity or the tilt angle is increased to some extent. Become. Therefore, the smaller the image display device with a wide angle of view, the larger the tilt angle of the reflecting surface,
An important issue is how to correct the occurrence of high-order coma aberration.

In order to correct such complicated coma aberration, at least one surface of the eyepiece optical system, preferably a reflecting surface is an eccentric aspherical surface so that the power of the optical system with respect to the visual axis. Can be made asymmetrical, and the effect of an aspherical surface can be utilized off-axis, so that it becomes possible to effectively correct coma aberration including on-axis.

It is effective for aberration correction that the reflecting surface having at least one positive power constituting the prism body is an anamorphic surface. In other words, as described below,
The Z axis that makes the direction of the observer's visual axis from the origin to the eyepiece optical system positive, the Y axis that is orthogonal to the observer's visual axis, and is positive from the bottom to the top in the vertical direction when viewed from the observer's eye When defined as the X axis that is orthogonal to the visual axis of the observer and is positive from left to right in the left-right direction when viewed from the observer's eye, the radius of curvature in the YZ plane and the XZ plane orthogonal to this plane Is that the surfaces have different radii of curvature.

This condition is a condition for correcting an aberration caused by the reflecting surface being decentered or inclined with respect to the visual axis. In general, when the spherical surface is decentered, the light ray incident on the surface has different curvatures with respect to the light ray in the incident surface and in the surface orthogonal to the incident surface. Therefore, in the eyepiece optical system in which the reflecting surface is arranged in front of the observer's eyeball in a decentered or inclined manner with respect to the visual axis as in the present invention, the observation image on the visual axis, which is the center of the observation image, is not Point aberration occurs. In order to correct this astigmatism on the axis, the radius of curvature of at least one reflecting surface having a positive power, which constitutes the prism body, may be different between the entrance surface and the surface orthogonal to the entrance surface. Becomes important.

Further, at least one of the prism bodies is formed.
If the reflecting surface having two positive powers is a free-form surface, the above-described effect of the aspherical surface or the anamorphic surface can be satisfied, so that the aberration generated in the eyepiece optical system can be effectively corrected. is there.

Here, the free curved surface is a curved surface expressed by the following equation (1). Here, x, y, and z represent orthogonal coordinates, C _nm is an arbitrary coefficient, and k and k ′ are also arbitrary.

In the above-mentioned image display device, by providing the image display element and the eyepiece optical system with respect to the head of the observer, the observer can observe a stable image.

Further, by providing a means for positioning the image display element and the eyepiece optical system with respect to the observer's head so that they can be mounted on the observer's head, the observer can freely observe the observing posture and the observing direction. The image can be observed with.

Further, by providing the supporting means for supporting at least two sets of such image display devices at a constant interval, the observer can easily observe with both the left and right eyes. Further, it is possible to enjoy a stereoscopic image by displaying images with parallax on the image display surfaces of the left and right image display devices and observing them with both eyes.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the image display device of the present invention will be described below with reference to the drawings. Example 1
The configuration parameters of will be described later, but in the following explanation,
The surface number is shown as a surface number for reverse tracking from the observer's pupil position 1 to the eyepiece optical system 3. Then, as shown in FIG. 3A, the coordinate is obtained by using the iris position 1 of the observer as the origin, and the observer's visual axis 2 as the Z axis whose direction from the origin to the eyepiece optical system 3 is positive, The Y-axis, which is orthogonal to the observer's visual axis 2 and is positive in the vertical direction from the bottom to the top when viewed from the observer's eye, is orthogonal to the observer's visual axis 2, and is right to the left in the horizontal direction when viewed from the observer's eye. Is defined as the X axis. That is, the inside of the paper of FIG. 3A is taken as the YZ plane, and the plane perpendicular to the paper is taken as the XZ plane. It is assumed that the optical axis is bent in the YZ plane of the drawing.

In the constituent parameters described later, regarding the surfaces on which the eccentricity amounts Y and Z and the inclination angle θ are described, regarding the two surfaces, the surface spacing given by the distance along the Z axis from the one surface is set. The position becomes a reference point, and the eccentric amount in the Y-axis direction and the Z-axis direction of the top of the surface from the reference point, and
It means the angle of inclination of the center axis of the surface from the Z axis,
The plane is Y of the top of the plane from the top of the two planes that are the reference planes.
Axial amount in the axial direction, Z-axis direction, and Z of the central axis of the surface
It means the tilt angle from the axis, and with respect to 5 planes, the eccentric amount in the Y-axis direction and the Z-axis direction of the plane top of that plane from the plane tops of the 4 planes that are the reference planes, and the It means an inclination angle from the Z axis, and 6 planes are the eccentric amount in the Y axis direction and the Z axis direction of the center of the plane from the center of the 1 plane which is the reference plane, and the Z axis of the center axis of the plane. Means the tilt angle from. In that case, positive θ means counterclockwise rotation, and the interplanar spacing is shown with the direction of reverse tracking along the optical axis as positive.

Further, in each surface, an aspherical shape which is non-rotationally symmetric has coordinates R _y and R _{x which} are paraxial curvature radii in the YZ plane (paper surface) and X- Paraxial radii of curvature in the Z plane, K _x and K _y are the X-Z plane and Y-, respectively.
The conic coefficients AR and BR in the Z plane are the fourth-order and sixth-order aspherical coefficients rotationally symmetric with respect to the Z axis, respectively, and AP and BP are the fourth-order and sixth-order non-spherical coefficients rotationally asymmetric with respect to the Z axis, respectively. Assuming a spherical coefficient, the aspherical expression is as shown below.

Z = [(X ² / R _x ) + (Y ² / R _y )] / [1+
｛1- (1 + K _x ) (X ² / R _x ² )-(1 + K _y ) (Y ² / R _y ² )｝
^{1/2] + AR [(1-} AP) X 2 + (1 + AP) Y 2] 2 + B
R [(1-BP) X 2 + (1 + BP) Y 2] 3 The refractive index of the medium between the surfaces is expressed by the refractive index of the d-line. The unit of the length is mm.

Regarding this embodiment, FIG. 3A is an optical path diagram of the YZ cross section when observing the image of the image display device, and FIG.
(B) is an optical path diagram of the YZ cross section when observing the image of the external world, in which 1 is the observer's pupil position, 2 is the observer's visual axis,
Reference numeral 3 is an eyepiece optical system, 4 is an image display element, 11 is a first surface of the eyepiece optical system 3, 12 is a second surface forming a reflecting surface and a transmitting surface having positive power of the eyepiece optical system 3, and 13 is an eyepiece optical system. The third surface 14 of the system 3 is the fourth surface of the eyepiece optical system 3.

The specifications of this embodiment are a horizontal angle of view of 30 °, a vertical angle of view of 22.72 °, and an exit pupil diameter of 4 mm. FIG.
In (a), the second surface 12 and the third surface 13 of the internal reflection surfaces of the prism body that is the eyepiece optical system 3 satisfy the total reflection condition. Therefore, it is possible to observe both the electron image and the external image without coating the two reflecting surfaces with a half mirror.

In the case of observing an electronic image, the actual light ray path in this embodiment is such that, as shown in FIG. 3A, the light ray bundle emitted from the image display element 4 is the fourth ray of the eyepiece optical system 3.
The light is refracted by the surface 14 and enters the eyepiece optical system 3, is totally reflected by the third surface 13, is totally reflected by the second surface 12, is refracted by the first surface 11, and is emitted from the eyepiece optical system 3. The iris position of the pupil or the center of rotation of the eyeball is projected into the eyeball of the observer as the exit pupil 1.

When observing the external world image, as shown in FIG. 3B, the prism body 3 is rotated clockwise in the figure and moved upward. With reference to the position shown in FIG. 3A, clockwise rotation is 30.19 ° and Y direction is 20.1.
It is moved 6 mm.

In actual use, as shown in FIGS. 1 and 2, a light shielding means 5 such as a liquid crystal shutter is provided outside the eyepiece optical system 3. Then, the image of the image display element 4 is displayed, and the image of the image display element 4 can be observed by blocking the light with the light blocking means 5. Further, the image on the image display element 4 is erased, the light-shielding means 5 is set in the transmitting state, and the eyepiece optical system 3 is rotated.
By moving, the external image can be observed. Next, the configuration parameters of the above embodiment will be shown.

Surface number Curvature radius Spacing Refractive index Abbe number (Eccentricity) (Tilt angle) 1 ∞ (pupil) 28.736 2 R _y 85.714 1.6200 60.30 R _x 46.018 Y -10.163 θ -3.81 ° K _y -20.000000 Z 0.000 K _x -6.903310 AR 0.161497 × 10 ^-5 BR -0.353389 × 10 ^-9 AP -0.189573 BP -0.293763 3 -152.866 1.6200 60.30 Y 4.363 θ 39.36 ° Z 30.308 4 -152.912 1.6200 60.30 Y 3.066 θ 38.35 ° Z 10.883 5 R _y -53.262 Y 10.000 θ -17.11 ° R _x 141.921 Z 60.600 K _y 0 K _x 0 AR -0.100878 × 10 ^-5 BR 0.152172 × 10 ^-9 AP -0.149575 × 10 ¹ BP 0.942350 6 (image display device) Y -36.324 θ -21.14 ° Z 76.573.

Although the image display apparatus of the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments and various modifications can be made. To configure the image display device of the present invention as a head-mounted image display device (HMD) 21, as shown in a sectional view of FIG. 4A and a perspective view of FIG. Attach it to the observer's head and use it. FIG. 4A is a cross-sectional view when observing the electronic image of FIG. 1.

The above-described image display device of the present invention can be configured as follows, for example. [1] In an image display device including an image display element that displays an image and an eyepiece optical system that projects an image formed by the image display element and guides it to an eyeball of an observer, the eyepiece optical system has an optical surface. It has at least three surfaces, the space formed by the at least three surfaces is filled with a medium having a refractive index larger than 1, and has at least one positive power that is eccentric or inclined with respect to the observer's visual axis. The prism body has a reflecting surface, and the prism body has a first arrangement position that guides the light beam emitted from the image display element to the eyeball of the observer and the eyeball of the observer by passing the light beam from the outside. The image display device is configured so as to be rotatable or movable between the second position and the second position.

[2] Among the surfaces constituting the prism body, the two opposing surfaces have substantially zero power with respect to the light flux from the outside world passing through the two surfaces at the second arrangement position. The image display device according to the above [1].

[3] At the first arrangement position, when the light beam emitted from the image display element is internally reflected by the prism body, the total reflection condition is satisfied so that the condition is satisfied. The image display device according to [1].

[4] The image display device according to the above [1], wherein the image display element and the eyepiece optical system can be rotated or moved at the same time.

[5] The image display device according to the above [1], characterized in that a light-shielding means is provided outside the surface of the eyepiece optical system opposite to the observer.

[6] The image display device according to the above [1], wherein the at least one reflecting surface having a positive power is an aspherical surface.

[7] The image display device according to the above [6], wherein the at least one reflecting surface having a positive power is an anamorphic surface.

[8] The image display device according to the above [6], wherein the at least one reflecting surface having a positive power is a free-form surface.

[0050]

[9] The image display device according to any one of [1] to [8], further comprising positioning means for positioning the image display element and the eyepiece optical system with respect to the observer's head. .

[10] From the above [1], which has a supporting means for supporting the image display element and the eyepiece optical system with respect to the observer's head and can be mounted on the observer's head.

The image display device according to any one of [9].

[11] The image display device as described in any one of [1] to [10] above, which has a supporting means for supporting at least two sets of the image display device at a constant interval.

[0053]

As is clear from the above description, according to the image display device of the present invention, the observation angle is wide, the size is small and the weight is small.
Moreover, it is possible to provide an image display device suitable for a head-mounted image display device capable of observing an external image by a simple operation without using a special optical element other than the optical element of the eyepiece optical system. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of an image display device of the present invention when observing an electronic image.

FIG. 2 is a diagram showing a state of the image display device of the present invention when an external image is observed.

FIG. 3 is a sectional optical path diagram of one embodiment of the present invention.

FIG. 4 is a sectional view and a perspective view of a head-mounted image display device according to the present invention.

[Explanation of symbols]

 1 ... Observer pupil position 2 ... Observer visual axis 3 ... Eyepiece optical system 4 ... Image display element 5 ... Shading means 11 ... First surface of eyepiece optical system 12 ... Second surface of eyepiece optical system 13 ... Eyepiece optical system Third surface 14 ... Fourth surface of eyepiece optical system 20 ... Headband 21 ... Head mounted image display device (HMD)

Claims (3)

[Claims] 1. An image display device comprising an image display element for displaying an image and an eyepiece optical system for projecting the image formed by the image display element to guide it to an observer's eyeball. At least one positive power having at least three surfaces, the space formed by the at least three surfaces being filled with a medium having a refractive index greater than 1 and eccentric or inclined with respect to the observer's visual axis. A prism body having a reflection surface having a first arrangement position for guiding the light flux emitted from the image display element to the observer's eyeball, and the observer by allowing a light flux from the outside to pass therethrough. The image display device is configured so as to be rotatable or movable between a second arrangement position that leads to the eyeball. 2. The power of the two opposing surfaces of the surfaces constituting the prism body is substantially zero with respect to the light flux from the outside world passing through these two surfaces at the second arrangement position. The image display device according to claim 1, wherein the image display device is a display device. 3. The first arrangement position is configured to satisfy a total reflection condition when a light beam emitted from the image display element is internally reflected by the prism body. 1. The image display device according to 1.