JPH0651264A - Head-mounted image display device - Google Patents

Abstract

PURPOSE:To provide a head-mounted image display device which displays a bright electron image by enhancing the reflectance of light coming from a liquid display element through an optical system for combining it to an external image. CONSTITUTION:Light from a liquid crystal display element 1 is S-spolarized, impinges via a lens 8 on a polarizing interference filter 23, is reflected at the overall surface of the filter, and impinges on an eye 4. Being naturally polarized, external light 5 has its P-components alone transmitted through the filter and allowed to reach the eye 4. Therefore, part of the external light 5 and an electron image of the liquid crystal display element 1 are superimposed on each other by means of the polarizing interference filter 5 and impinge on the eye 4 so that a bright electron image is observed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable image display device, and more particularly to a see-through type head-mounted image display device held on the observer's head.

[0002]

2. Description of the Related Art Conventionally, as a see-through type head-mounted image display device, there has been known a display device which synthesizes an electronic image and an external image by a half mirror or selects and displays one of them. JP-A-4-1717). As shown in the plan view of FIG. 6, the typical configuration thereof is that the light of an electronic image displayed by the liquid crystal display element 1 is reflected by a half mirror 2 such as a concave mirror and is reflected on an eyeball 4 of an observer's head 3. In addition to being guided, the light 5 of the external world image is guided to the eyeball 4 through the half mirror 2, and both are combined and displayed.

[0003]

However, when combining the electronic image and the external image with the half mirror 2 as described above, about half of the light of the electronic image displayed by the liquid crystal display element 1 is the transmitted light 6. However, there is a drawback that only about half of the remaining light is reflected by the half mirror 2, and the electronic image reaching the eyeball 4 becomes dark and difficult to see.

The present invention has been made in view of the above circumstances, and an object thereof is a head-mounted image display device for synthesizing an electronic image from a liquid crystal display element and an external image by using a synthesizing optical system. In order to improve the reflectance of light from the liquid crystal display element by the composite optical system, a bright electronic image can be displayed.

[0005]

A head-mounted image display device of the present invention which achieves the above object, is a liquid crystal display device for displaying an image, and a composition for combining an image from the liquid crystal display device and an external image. In a head-mounted image display device having an optical system, the composite optical system is configured to have a polarization reflection characteristic for light in a specific polarization direction from the liquid crystal display element. It is a thing.

[0006]

In the present invention, since the synthetic optical system is constructed so as to have the polarization reflection characteristic with respect to the light of the specific polarization direction from the liquid crystal display element, this synthetic optical system should not be emitted from the liquid crystal display element. Since most of the polarized light that is reflected is reflected,
An observer can see a bright electronic image from the liquid crystal display element.

In this case, any known polarization beam splitter can be used as the synthetic optical system.
In particular, by using the polarization interference filter, the head-mounted image display device can be constructed in a lightweight and compact form,
preferable.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle and embodiments of the present invention will be described below with reference to the drawings. The light emitted from the liquid crystal display element is usually linearly polarized in a specific direction. An example of the liquid crystal display device is shown in FIG. This shows one example of the structure of a high resolution active matrix type liquid crystal display element. Briefly, the liquid crystal 10 is enclosed between two glass substrates 11 and 12, and one substrate 11 The color filter layer 13 and the common electrode 14 are arranged on the inner surface of the substrate, and the data lines 15 and the scanning lines 16 are arranged in a matrix on the inner surface of the other substrate 12, and the TFT (thin film transistor) 1 is arranged at the intersection thereof.
7 and the transparent drive electrode 18 are connected to each other,
Outside of 12, polarizing plates 19 and 20 orthogonal to each other are arranged. Drive electrode 18 and common electrode 14
When no voltage is applied between the two, the linearly polarized light that has passed through the polarizing plate 20 is, for example, the TN mode liquid crystal 10 in that portion.
The polarization direction is rotated by 90 ° by and the light passes through the other polarizing plate 19, but when a voltage is applied between the two electrodes 18 and 14, the liquid crystal 10 loses its optical rotatory power, and the polarization plane does not rotate. It is blocked by the polarizing plate 19 and cannot pass through. Therefore, the display image of such a liquid crystal display element is linearly polarized in a specific direction. Therefore, for example, a polarization interference filter is used as a combining optical system that combines such light and external light. This is a kind of polarizer composed of an obliquely incident interference filter, and for example, S-polarized light is reflected 100% and P-polarized light is transmitted 100%. By using such a synthetic optical system, it is possible to design so that all the polarized light of the light emitted from the liquid crystal display element is reflected, and most of the electronic images enter the eyes of the observer, and a bright image can be displayed.

The first embodiment will be described with reference to FIG. The polarization interference filter 23 used in place of the conventional half mirror is composed of a dielectric multilayer interference filter 22 provided on the surface of the glass 21. In this case,
It is configured to reflect all S-polarized light and pass P-polarized light. The light from the light source 9 is collimated by the lens 7,
The liquid crystal display element 1 as illustrated in FIG. 5 is illuminated. In this case, the light from the liquid crystal display element 1 is S perpendicular to the paper surface.
It is polarized. This light enters the polarizing interference filter 23 through the lens 8 and is all reflected on the surface,
It enters the eye 4. The ambient light 5 is naturally polarized light, and therefore only the P component therein is transmitted and reaches the eye 4. Therefore, a part of the external light 5 and the electronic image of the liquid crystal display element 1 are overlapped by the polarization interference filter 23 and enter the eye 4, and a bright electronic image is observed. As described above, the electronic image can be brightened by using the polarization interference filter 23 as the combining optical system.

Next, FIG. 2 shows the configuration of the second embodiment.
In this embodiment, a polarizing plate 24 and a polarization rotator 26 are provided on the external light incident side of the polarization interference filter 23 of FIG. 1, and the driver 25 is attached to the polarization rotator 26 to control the external light 5. This is an example. Also in this example, the polarization interference filter 23 is configured to reflect all S-polarized light and pass all P-polarized light. Therefore, all the light from the liquid crystal display element 1 is reflected by the polarizing interference filter 23 and reaches the eye 4 as in the first embodiment. The external light 5 will be described with reference to FIGS. 3 (a) and 3 (b). The light 5 from the outside world first enters the polarizing plate 24 that is set to transmit only P-polarized light. The light (P-polarized light) transmitted through the polarizing plate 24 then enters the polarization rotator 26. The polarization rotator 26 changes the polarization direction of incident light by 90 °.
It can be changed, and a liquid crystal or a crystal having an electro-optical effect can be used. Now, as shown in FIG. 7A, if the drive from the driver 25 is turned off, the polarization direction rotation ability of the polarization rotator 26 is cut off, and the P-polarized light is transmitted as it is, it is incident on the polarization interference filter 23. Since the light to be emitted is P-polarized light, it passes through the polarization interference filter 23 and the external light 5 is visible to the eye 4. On the other hand, when the polarization rotator 26 is turned on as shown in FIG. 6B, the incident P-polarized light is converted into S-polarized light, reflected by the polarization interference filter 23, and the external light 5 does not reach the eye 4. . Therefore, in this embodiment, the polarization rotator 26 is turned on.
By performing the OFF control, the external image can be selectively observed.

Next, FIG. 4 shows the configuration of the third embodiment. In the first and second embodiments, the concave mirror located immediately in front of the eye of the head-mounted image display device is the synthetic optical system, but the concave mirror of the eyepiece optical system is a total reflection mirror. ,
The synthesizing optical system may be composed of a planar optical element at another position. This example is this embodiment, and in FIG. 4, a convex mirror 27 and a concave mirror 28 arranged immediately before the eyeball are used to guide the light 5 from the outside world to the eye 4. Then, a polarization interference filter 23 that synthesizes the electronic image from the liquid crystal display element 1 with the external light is arranged in the optical path between the convex mirror 27 and the concave mirror 28, and the polarization interference filter 23 reflects the liquid crystal display element 1 from the liquid crystal display element 1. Light is reflected by the concave mirror 28 and reaches the eye 4. In this embodiment as well, a bright electron image can be observed as in the first embodiment. Further, by disposing the polarizing plate 24 and the polarization rotator 26 in front of the polarization interference filter 23 or in front of the convex mirror 27 as in the second embodiment, the observation of the external world image can be selectively performed.

The head-mounted image display apparatus of the present invention has been described above based on some embodiments, but the present invention is not limited to these embodiments and various modifications can be made. For example, as a synthetic optical system, in the above embodiments,
Although the polarization interference filter is used in each of the above cases, a known polarization beam splitter such as a prism made of a birefringent crystal may be used instead.

[0013]

As is apparent from the above description, according to the head-mounted image display device of the present invention, the synthetic optical system has the polarization reflection characteristic for the light in the specific polarization direction from the liquid crystal display element. Since the composite optical system is configured as described above, most of the polarized light emitted from the liquid crystal display element is reflected, so that the observer can see a bright electronic image from the liquid crystal display element.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of a first embodiment of a head-mounted image display device of the present invention.

FIG. 2 is a plan view showing a configuration of a second embodiment.

FIG. 3 is a diagram for explaining the operation of the second embodiment.

FIG. 4 is a plan view showing a configuration of a third embodiment.

FIG. 5 is a perspective view showing an example of the configuration of a high resolution active matrix type liquid crystal display element.

FIG. 6 is a plan view showing a configuration of a conventional see-through type head-mounted image display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element 4 ... Eye 5 ... External light 7, 8 ... Lens 9 ... Light source 21 ... Glass 22 ... Interference filter 23 ... Polarization interference filter 24 ... Polarizing plate 25 ... Driver 26 ... Polarization rotator 27 ... Convex mirror 28 ... concave mirror

Claims (1)

[Claims] 1. A head-mounted image display device having a liquid crystal display element for displaying an image and a combining optical system for combining an image from the liquid crystal display element and an external image, wherein the combining optical system is the liquid crystal. A head-mounted image display device, which is configured to have a polarization reflection characteristic with respect to light in a specific polarization direction from a display element.