JPH0764014A - Picture display device - Google Patents

Abstract

PURPOSE:To obtain enlarged virtual image with a desired size, to shorten the length of an optical path between a picture display body and an eyepiece and to more miniaturize the whole of a device. CONSTITUTION:In the picture display device enlarging the picture displayed on a liquid crystal display panel 14 by using the eyepiece 16 and observing the virtual image thereof, a first refractive index distribution lens 17 is made to intervene between the panel 14 and the lens 16. Therefore, since the picture of the panel 14 is enlarged by the lens 17 and the enlarged virtual image is further enlarged to the desired size by the lens 16, the length of the optical path between the panel 14 and the lens 16 can be shortened. Thus, the whole of the device is more miniaturized.

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 such as a head mounted display.

[0002]

2. Description of the Related Art In image display devices, a device having a wide field of view is required, and in response, a device for enlarging and projecting an image on a large screen has been commercialized. However, in such a projection type image display device, the entire device becomes large,
It is expensive. Therefore, conventionally, a compact head mounted display that can be worn on the head and observes an image has been proposed.

FIG. 6 is a schematic diagram showing an example of this head mounted display. The head mounted display includes a ring-shaped head band 1 to be worn on the head of a user and a device case 2 attached to the head band 1. The headband 1 is stretchable in the circumferential direction, and earphones (not shown) for transmitting audio signals through the band are provided on both sides of the headband 1. The device case 2 is a box-like member whose front side is formed into a curved surface shape that is in close contact with the user's face, and left and right viewfinders 3 are provided on the front surface of the device case 2 and the eyepieces for enlargement are provided in the respective viewfinders 3. A lens 4 is provided. Further, inside the device case 2, there are a liquid crystal display panel (image display body) 5 for displaying an image such as a television image, a reflection mirror 6 for reflecting the image light from the liquid crystal display panel 5 toward the finder 3. It is provided. In addition,
A circuit board 7 that drives the liquid crystal display panel 5 is provided on the back surface side of the reflection mirror 6, and a backlight unit that illuminates the liquid crystal display panel 5 on the back surface side (upper surface side in FIG. 6) of the liquid crystal display panel 5. 8 are provided.

In such a head mounted display, the front side of the device case 2 is applied to the face, the headband 1 is attached to the head, the earphones are inserted into the left and right ears, and in this state, the left and right viewfinders 3 are looked into. When viewed, the image displayed on the liquid crystal display panel 5 is magnified by the eyepiece lens 4, a virtual image thereof can be observed, and a sound corresponding to the image can be heard by the earphone.

[0005]

However, in such a head mounted display, since the magnified virtual image of the image displayed on the liquid crystal display panel 5 is formed only by the eyepiece lens 4, the eyepiece lens 4 and the liquid crystal display panel 5 are formed. If the optical path length between and is not set to be long, a magnified virtual image of a desired size cannot be obtained, and there is a problem that further miniaturization cannot be achieved.

This will be explained based on the principle diagram shown in FIG. Assuming that the eyepiece lens 4 has a focal length f of 27 mm and the liquid crystal display panel 5 is a 0.7-inch type, it is 31.1 inches behind the liquid crystal display panel 5 (to the left in FIG. 7) about 1146.6 mm. In order to obtain a magnified virtual image, if the distance between the eyepiece 4 and the eye 9 is set to, for example, about 13.6 mm, the distance between the eyepiece 4 and the liquid crystal display panel 5 is about 2 mm.
It is 6.4 mm, and the optical path length from the eye 9 to the liquid crystal display panel 5 is about 40 mm. When such an optical system is incorporated in the equipment case 2 shown in FIG.
Even if the reflection mirror 6 is interposed between the liquid crystal display panel 5 and the liquid crystal display panel 5, considering the size of the liquid crystal display panel 5 and the like, the size of the device case 2 including the finder 3 is about 40 mm in length and high. Is about 21 mm, which is a large head-mounted display.

The present invention has been made in view of the above circumstances, and it is possible to obtain a magnified virtual image of a desired size and to shorten the optical path length between the image display body and the eyepiece lens. An object of the present invention is to provide an image display device that can be further miniaturized.

[0008]

In order to achieve the above object, the present invention provides an image display device in which an image displayed on the image display device is magnified by an eyepiece and a virtual image thereof is observed. A gradient index lens for enlarging the image of the image display is interposed between the eyepieces. In this case, it is desirable that the gradient index lens has minute lenses corresponding to each pixel of the image display body, and each pixel be enlarged by these minute lenses.

[0009]

According to the present invention, the image of the image display body is magnified by the gradient index lens, and the magnified virtual image is further magnified to a desired size by the eyepiece lens. Therefore, the image between the image display body and the eyepiece lens is enlarged. The optical path length can be shortened, and thus the overall size of the device can be further reduced. In this case, as described in claim 2, if the gradient index lens has minute lenses corresponding to each pixel of the image display body, and each pixel is enlarged by these minute lenses, the refractive index Since the virtual image of each pixel magnified by each minute lens of the distributed lens overlaps with the virtual image of the adjacent pixel at the peripheral portion, for example, if each pixel is any one of red, green, and blue color pixels, color mixing does not occur. The image quality is improved and a good color image can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the appearance of the head mounted display of the present invention. In this head mounted display, a device case 11 is attached to a ring-shaped head band 10 to be worn on the head of a user. The headband 10 has elasticity in the circumferential direction, and earphones 12 through which audio signals are sent through the band are provided on both sides of the headband 10. The device case 11 is a box-shaped case whose front side is formed into a curved surface shape that is in close contact with the user's face, and left and right viewfinders 13 are provided on the front side.

FIG. 2 shows the internal structure of the equipment case 11. A liquid crystal display panel (image display body) 1 for displaying an image such as a television image is provided on the upper portion of the device case 11.
4 are arranged. A backlight unit 15 for illuminating the liquid crystal display panel 14 is provided on the back side (upper surface side in the figure) of the liquid crystal display panel 14, and an eyepiece lens is provided in front of the liquid crystal display panel 14 (lower side in the figure). 16
Are arranged. A first gradient index lens 17 described later is provided between the eyepiece lens 16 and the liquid crystal display panel 14.
And a second gradient index lens 18 to be described later is interposed between the first gradient index lens 17 and the liquid crystal display panel 14. Further, in front of (in the same figure, below) the eyepiece lens 16, there are arranged respective gradient index lenses 17, 18 and a reflection mirror 19 for reflecting the image light passing through the eyepiece lens 16 toward the finder 13. A circuit board 20 that drives the liquid crystal display panel 14 is provided on the back surface of the reflection mirror 19.

FIG. 3 is an enlarged sectional view of a main part from the liquid crystal display panel 14 to the eyepiece lens 16. Liquid crystal display panel 1
Reference numeral 4 denotes a liquid crystal 23 enclosed between a pair of glass substrates 21 and 22 having transparent electrodes formed on opposite surfaces thereof. The location where the transparent electrodes face each other is a pixel 24, and the pixels 24 are arranged in a matrix. In addition, a black stripe 25 is provided between each pixel 24. In this case, each pixel 24 is a color pixel having a color filter of red, blue, or green. The first gradient index lens 17 is a flat plate microlens in which minute convex lenses are embedded in a matrix in a substrate, each convex lens corresponds to each pixel 24 of the liquid crystal display panel 14, and the rear (upper side) of the liquid crystal display panel 14 (upper side). ), An enlarged virtual image of each pixel 24 is created. The second gradient index lens 18 is a flat plate microlens in which minute concave lenses are embedded in a matrix in a matrix like the first gradient index lens 17, and each concave lens is the first gradient index lens. The principal point of each convex lens is adjusted corresponding to each of the seventeen convex lenses. The eyepiece lens 16 has the same structure as the conventional example.

In such a head mounted display, each convex lens of the first gradient index lens 17 corresponds to each pixel 24 of the liquid crystal display panel 14, and the principal point is adjusted by the second gradient index lens 18. Therefore, the liquid crystal display panel 1 is provided by the first gradient index lens 17.
Each of the pixels 24 of No. 4 can be magnified well, and the magnified virtual image is further magnified to a desired size by the eyepiece lens 16. Therefore, the optical path length between the liquid crystal display panel 14 and the eyepiece lens 16 can be extremely reduced. The size of the entire apparatus can be greatly reduced.

This will be described with reference to the principle diagram shown in FIG. The focal length f of each convex lens of the first gradient index lens 17 is 3.77 mm, the focal length f of the second gradient index lens 18 is -0.46 mm, and the size of the liquid crystal display panel 14 is the same as the conventional one. As the same 0.7-inch type, each of the gradient index lenses 17 and 18 enlarges about 31.7 times in size behind the liquid crystal display panel 16 (to the left in FIG. 4) about 21.7 mm corresponding to a pixel. To create a virtual image,
The pitch (center distance) between the liquid crystal display panel 14 and the second gradient index lens 18 is about 0.7 mm, and the pitch between the second gradient index lens 18 and the first gradient index lens 17 is about. It will be 3 mm. Then, in order to obtain a magnified virtual image of 31.1 inches at a position approximately 1146.6 mm behind the magnified virtual image with the eyepiece lens 16 having the same focal length f (27 mm) as in the conventional case, the magnified virtual image is obtained by If the distance is set to about 13.6 mm, which is the same as the conventional one, the pitch between the first gradient index lens 17 and the eyepiece lens 16 is about 1 m.
m. Therefore, the center-to-center distance between the eyepiece lens 16 and the liquid crystal display panel 14 is about 4.7 mm, and the optical path length from the eye 26 to the liquid crystal display panel 14 is about 18.3 mm, which is extremely short. When such an optical system is incorporated in the equipment case 11 shown in FIG. 2, the eyepiece lens 16 and the eye 26
Even if the size of the liquid crystal display panel 5 is taken into consideration by interposing the reflection mirror 19 between the finder 1 and
The size of the device case 11 including 3 is about 21 mm in length and about 20 mm in height, which is very small as compared with the conventional one.

Further, in this head mounted display, as shown in FIG. 5, each pixel 24 of the liquid crystal display panel 14 is enlarged about three times by the first gradient index lens 17 and the second gradient index lens 18. As a result, the magnified virtual image of each pixel 24 overlaps with the virtual image of each adjacent pixel 24 and the peripheral portion thereof.
The green and blue colors are mixed well, and a good color image can be obtained.

In the above embodiment, the liquid crystal display panel 1
Although the second gradient index lens 18 is interposed between the first gradient index lens 4 and the first gradient index lens 17, the first refraction index lens 17 is adjusted so that the principal point of the first gradient index lens 17 need not be adjusted. If the gradient index lens 17 can be manufactured, it is not always necessary to interpose the second gradient index lens 18.

[0017]

As described above, according to the present invention, since the gradient index lens for enlarging the image on the image display is interposed between the image display and the eyepiece, the gradient index lens is provided. By enlarging the image of the image display body, it is possible to further magnify this magnified virtual image to a desired size with an eyepiece lens, and thus the optical path length between the image display body and the eyepiece lens can be shortened, It is possible to further reduce the size of the entire device.

[Brief description of drawings]

FIG. 1 is an external perspective view of a head mounted display of the present invention.

FIG. 2 is a diagram showing the internal structure of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of FIG.

FIG. 4 is a principle diagram of the optical system shown in FIG.

FIG. 5 is a diagram for explaining overlapping of virtual images corresponding to pixels in which each pixel of the liquid crystal display panel is magnified by the first gradient index lens.

FIG. 6 is a schematic configuration diagram of a conventional head mounted display.

7 is a principle diagram of FIG.

[Explanation of symbols]

 14 liquid crystal display panel 16 eyepiece lens 17 first gradient index lens 24 pixels

Claims (2)

[Claims] 1. An image display device for enlarging an image displayed on an image display by an eyepiece and observing a virtual image thereof, wherein the image of the image display is enlarged between the image display and the eyepiece. An image display device characterized by interposing a gradient index lens for the purpose. 2. The gradient index lens has minute lenses corresponding to respective pixels of the image display body, and each pixel is enlarged by these minute lenses. Image display device.