JPH07218861A - Image display device - Google Patents

Abstract

PURPOSE:To adjust the luminance of a displayed image in accordance with the brightness of the outside at the time of observing this image overlapping image information of the outside by illuminating image information, which is displayed on a pair of reflection type image display elements, with the luminous flux from an illuminating system to display this image information in the front of observer's eyeballs by a pair of optical systems. CONSTITUTION:Image information displayed on an image display element 1a illuminated by the luminous flux of parallel rays from an illuminating system 101 is displayed as an enlarged virtual image in a prescribed position in the front of the observer through a semitransparent mirror 4a and a semitransparent curved surface mirror 3a by an optical system 2a and spatially overlaps image information of the outside, and they are observed in the same visual field. At this time, the balance between the brightness of image information on the image display element 1a and that of the outside is adjusted in accordance with the brightness of the outside to keep the satisfactory observation state of both image information. A reflection type spatial light modulating element called DMD is used as the image information element.

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, it is provided in front of an observer's head, and image information displayed by an image display element is displayed as a virtual image at a predetermined position in front of the observer's eye by an optical system. In this case, the present invention relates to an image display device which is small in size, has a large screen, can perform high-definition display, and can display a stereoscopic image.

[0002]

2. Description of the Related Art Conventionally, a large CRT display device, a projection TV or the like has been used as a device for displaying image information displayed on an image display device such as a liquid crystal as a large screen image with a sense of reality.

However, these devices have problems that they require a large space, or that it is difficult to observe a good image unless the surroundings are darkened, and their use conditions are limited.

For this reason, recently, a light beam from an image displayed on an image display device is directly projected onto an eye (observer's pupil) by an optical system arranged very close to the observer's face, and an equivalent light is emitted. An image display device has been proposed in which image information on a large screen is observed as a virtual image.

FIG. 6 shows an example of such a device.
This is a description of the main part of the image display device proposed in Japanese Patent Publication No. 34512/1989. The image is displayed on the liquid crystal display (liquid crystal panel) 201 by the data sent by the signal line 206.

[0006] 201 is transmitted and illuminated by a backlight light source 204. A light beam 208 based on the image information displayed on the liquid crystal display 201 passes through a magnifying lens 203 including a concave lens and a convex lens, and then is reflected by a mirror 205 to become a reflected light beam 209, which is an eye of an observer 210 (an eye of the observer). )
It is incident on 207.

Therefore, the observer observes the display image with the light beam 209. At this time, the magnifying lens 203 displays the image displayed on the liquid crystal display 201 as a virtual image on the virtual image plane 202 at a predetermined distance from the pupil 207 of the observer via the mirror 205, for example, 5 m ahead.

An observer observes the image information displayed on the liquid crystal display 201 on the virtual image plane 202.

In addition, a head-mounted display called "eyephone" manufactured by VPL Research, Inc. has two sets of liquid crystal displays of about 3 inches for left and right eyes, and each display image is a Fresnel lens. An image with a three-dimensional effect is displayed by observing through.

In these conventional stereoscopic image display methods, an imaging optical system corresponding to each of the left and right eyes is prepared so as to respond to a visual difference (such as two images recorded in stereo and computer graphics with parallax). It is possible to give a three-dimensional effect by displaying an image.

Another conventional example of displaying an image having a stereoscopic effect is a three-dimensional image display device as disclosed in Japanese Patent Laid-Open No. 4-248583. This method selectively displays each part of the display object while changing the display position. The display image is presented in the vicinity of the position that should be a part of the most natural three-dimensional image, and the afterimage of the eye is displayed. Use the effect 3
I am observing a three-dimensional image.

Generally, in order to faithfully and naturally observe a stereoscopic image, the brightness of the left and right images to be observed by both eyes needs to be appropriately adjusted. Japanese Unexamined Patent Publication No. 62-272698 proposes an image display device in which illumination devices for the left and right eyes are provided and the amount of light can be adjusted.

[0013]

An image display device in which an image display element is arranged in the vicinity of both eyes of an observer and a virtual image of image information displayed on the image display element is observed. In order to be visible at the same time, it is preferable that the virtual image has a sufficiently high contrast, the brightness can be adjusted in a wide range according to the brightness of the external environment, and the entire system is small.

As a display element known in the conventional image display device, for example, a CRT can obtain an image with relatively high contrast and high brightness, but there is a problem that the entire system becomes large. Further, in a transmissive liquid crystal display, it is difficult to obtain a high-contrast image and the utilization efficiency of illumination light is not good, so it is difficult to achieve both miniaturization and high brightness.

Japanese Unexamined Patent Publication (Kokai) No. 60-97315 proposes an image display device which controls the amount of polarized light to adjust the brightness of a displayed image, but the utilization efficiency of illumination light is not always sufficient.

According to the present invention, the contrast of displayed image information is high, and the brightness of the displayed image can be adjusted in a wide range according to the brightness of the external environment when the image information of the external environment is observed in an overlapping manner. An object of the present invention is to provide an image display device which is small in size, can be easily mounted in front of an observer's eyeball, and can observe good image information.

[0017]

An image display device of the present invention illuminates image information displayed on a pair of reflective image display elements with a light beam from an illumination system, and outputs image information on the image display elements as a pair. It is characterized in that the image information is displayed at a predetermined position in front of the observer's eyeball by the optical system and the image information is observed.

In particular, the illumination system splits the light flux from the light source unit into two light fluxes by an optical element, and each of the two split light fluxes illuminates the pair of image display elements. Is illuminating the pair of image display elements with a parallel light beam, the illumination system has a light amount adjusting element for controlling the transmittance between the light source section and the optical element, and The transmittance of the light quantity adjusting element is controlled according to the brightness of the outside world.

[0019]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention.

In this embodiment, the case where the main part of the image display device is mounted in front of the observer's head is shown. 2 is shown in FIG.
FIG. 3 is an explanatory view showing only the illumination system 101 and the left-eye (right-eye) optical system of the image display device of FIG. The left and right eye systems are symmetrical.

Reference numeral 101 in the drawing is an illumination system. Image display elements 1a and 1b each are composed of a reflective liquid crystal display element, a spatial light modulator, etc., and are driven and controlled by a drive circuit (not shown) to display image information. A light source unit 6 has a light emitting unit 61 and a reflector 62 for reflecting and condensing the light flux emitted from the light emitting unit 61. Reference numeral 8 denotes a light amount adjusting element, which is composed of, for example, a liquid crystal element, and adjusts the amount of transmitted light of the light flux from the light source unit 6 based on a signal from the adjusting circuit 8a.

Reference numeral 7 denotes an optical element composed of a triangular reflection prism whose slopes 7a and 7b are reflecting surfaces, and splits the light flux from the light source unit 6 into two light fluxes for illuminating the image display elements 1a and 1b of the left and right eyes. ing.

Reference numerals 5a and 5b are semi-transmissive mirrors, respectively, which reflect the light flux reflected from the optical element 7 toward the image display elements 1a and 1b. The image display elements 1a and 1b are illuminated by a parallel light flux. Reference numerals 2a and 2b are optical systems, respectively, and image information displayed on the image display elements 1a and 1b are reflected by semi-transmissive mirrors 4a and 4b, which will be described later, and the semi-transmissive curved mirror 3
It is displayed as an enlarged virtual image at a predetermined position 1aa in front of the observer via a and 3b. 9 is the observer's pupil position.

In this embodiment, the image display elements 1a and 1b illuminated by the parallel luminous flux from the illumination system 101 are replaced with optical systems 2a and 2a.
b by semi-transmissive mirrors 4a, 4b and semi-transmissive curved mirrors 3a, 3b
The image is displayed as a magnified virtual image at a predetermined position 1aa in front of the observer via the, and is observed spatially overlapping the image information of the outside world in the same visual field.

At this time, the image display element 1 is controlled by controlling the transmittance (amount of transmitted light) of the light quantity adjusting element 8 according to the brightness of the outside world.
The brightness balance between the image information of a and 1b and the image information of the outside world is adjusted to maintain a good observation state of both image information.

The image display device according to the present embodiment is a reflection type liquid crystal display device, or the DMD proposed in JP-A-60-179781 and JP-A-61-210775.
A reflection type spatial light modulator called a. These reflective image display elements have good utilization efficiency of illumination light,
As a result, a high-luminance image can be easily obtained, and high contrast can be easily obtained.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention.

The present embodiment is different from the first embodiment in FIG. 1 in that the illumination system having a light source section and a light quantity adjusting element constituting one element of the image display device mounted in front of the observer's head is used for the left eye and the right. The difference is that a pair is provided for each of the eyes, and the other configurations are substantially the same.

In this embodiment, the light beams from the light source portions 6a and 6b are reflected by the semi-transmissive mirrors 5a and 5b via the light amount adjusting elements 8a and 8b (not shown), and the reflection type image display element 1a,
1b is illuminated with a parallel light beam.

The reflection type image display elements 1a and 1b are forwarded to the observer through the semitransparent mirrors 5a and 5b and the optical systems 2a and 2b through the semitransparent mirrors 4a and 4b and the semitransparent curved mirrors 3a and 3b. The image is displayed as a magnified virtual image at a predetermined position, and is spatially superposed on the image information of the outside world in the same manner as in Example 1, and is observed in the same visual field.

Also in this embodiment, the transmittances of the light amount adjusting elements 8a and 8b provided in front of the light source portions 6a and 6b are controlled in accordance with the brightness of the external environment in the same manner as in the first embodiment. As a result, the display brightness of the image display elements 1a and 1b is changed, and the image information in the external environment is favorably observed.

FIG. 4 is an explanatory view of a part of the optical system of Example 3 of the present invention.

In this embodiment, as compared with the first embodiment shown in FIG. 1, a telecentric optical system 10 is used as an optical system for focusing and displaying the reflection type image display elements 1a and 1b at a predetermined position in front of the observer.
The difference is that a and 10b are used, and other configurations are substantially the same.

Here, the telecentric optical system is a system in which an entrance pupil or an exit pupil is set at infinity, and in the system of the present invention, a light beam reflected vertically from each position of the image display elements 1a and 1b. Is an optical system that is superposed at the pupil position and forms an image at a predetermined position.

FIG. 5 is an explanatory diagram of the telecentric optical system 10 of this embodiment. In the figure, 12 is the pupil position. The figure shows a state in which the image display element 1 is imaged at the position 11 by the telecentric optical system 10.

[0036]

According to the present invention, by setting each element as described above, the contrast of the displayed image information is high, and the brightness of the outside world can be improved when the image information of the outside world is observed. According to the present invention, the brightness of the displayed image can be adjusted in a wide range, the entire system is small, and can be easily mounted in front of the eyeball of the observer, and an image display device capable of observing good image information can be achieved. You can

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a part of FIG.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 4 is an explanatory diagram of an optical system according to Example 3 of the present invention.

5 is an explanatory view of the optical system of FIG.

FIG. 6 is an explanatory diagram of a conventional image display device.

[Explanation of symbols]

 101 Illumination system 1, 1a, 1b Image display element 2a, 2b Optical system 3a, 3b Semi-transmissive curved surface mirror 4a, 4b, 5a, 5b Semi-transmissive mirror 6, 6a, 6b Light source section 7 Optical element 8 Light intensity adjusting element 9 Pupil position 10, 10a, 10b Telecentric optical system

Claims (5)

[Claims] 1. The image information displayed on a pair of reflective image display elements is illuminated by a light beam from an illumination system, and the image information on the image display elements is predetermined by a pair of optical systems in front of an eyeball of an observer. An image display device, characterized in that it is displayed at a position and the image information is observed. 2. The illumination system splits a light flux from a light source unit into two light fluxes by an optical element, and illuminates the pair of image display elements by the two split light fluxes. The image display device according to item 1. 3. The image display device according to claim 1, wherein the illumination system illuminates the pair of image display elements with a parallel light flux. 4. The image display device according to claim 2, wherein the illumination system has a light amount adjusting element for controlling the transmittance between the light source section and the optical element. 5. The image display device according to claim 4, wherein the transmittance of the light amount adjusting element is controlled according to the brightness of the outside world.