JP3151771B2 - Image display device - Google Patents

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 an enlarged image display device, such as a liquid crystal element, having an optical system having small image information (display information) mounted on the head or face of an observer. The present invention relates to an image display device to be observed as a virtual image of an angle of view.

[0002]

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

[0003] These image display devices require a large space, and if they are to be installed in a small room, there is a problem that an appropriate observation distance cannot be secured, and that individual persons cannot see different programs. Was.

For this reason, for example, in Japanese Patent Application Laid-Open No. Hei 3-203478, an eye (pupil of an observer) is directly transmitted to an eye using an optical system in which a light beam from an image display element is arranged near the observer's face as shown in FIG. An image display device has been proposed in which light is guided to a large screen to observe image information on a large screen.

The main parts of FIG.
Reference numeral 221L denotes a liquid crystal color television for the right and left eyes.
The image information displayed on the liquid crystal color televisions 221R and 221L is partially reflected by a trapezoidal beam splitter (half mirror) 222R (not shown) arranged in front of both eyes, and enters the concave mirror 223 in front. I do. The light beam reflected by the concave mirror 223 passes through the beam splitter 222R (222L) and enters the eye of an observer (not shown).

[0006] Thereby, the observer can see the liquid crystal color television 22
The image information displayed on 1R and 221L is observed as a virtual image at a predetermined position in front of the concave mirror 223.

In such an image display device, it is also possible to display display information having a parallax between the right eye and the left eye of the observer to observe a stereoscopic image.

Further, in Japanese Patent Application Laid-Open No. Hei 4-21920, an image displayed on a polarized light control type display is magnified by a convex lens, and the polarized image is polarized by a polarization spectroscopic means disposed in front of the pupil of the observer. There has been proposed an image display device capable of displaying the enlarged virtual image superimposed on an external scene by causing the virtual image to enter the pupil.

[0009]

In a conventional image display apparatus, a color television or a polarized light control type display used as a display element has all used a transmission type liquid crystal element illuminated with a backlight.

In the case of a TFT liquid crystal color television as a liquid crystal element, for example, a liquid crystal panel of a current product level has a low aperture ratio of about 40% and does not provide a sufficient transmittance. For this reason, in order to achieve sufficient display luminance, it is necessary to increase the amount of light of the backlight or to provide a sheet-like multi-lens array in the opening, which hinders the reduction in size and weight of the entire apparatus. . Further, since a large backlight is required, it is difficult to reduce power consumption.

There are various factors which lower the aperture ratio of the liquid crystal element. TFT, wiring, auxiliary capacitance,
And a black matrix portion on the color filter that covers the gaps between them. Therefore TF
The aperture ratio has been improved by reducing the dimension of T or wiring, or reducing the area of the auxiliary capacitance.

[0012] However, these methods have problems due to limitations due to the limitations of semiconductor process technology such as the TFT process.

Further, in the conventional image display apparatus, since the liquid crystal panel is magnified and observed with a lens or a concave mirror, pixels are observed very coarsely, and display quality is insufficient.

To solve this problem, there is a method of increasing the density of pixels of a liquid crystal panel. This method has a problem that as the density is increased, the number of elements such as TFTs and wirings is increased, and the aperture ratio is reduced.

In addition, a transmissive liquid crystal television requires two polarizing plates provided in a crossed Nicols state, which also causes a reduction in display luminance.

The present invention uses a reflection type liquid crystal element having an appropriate configuration as a display element, and achieves high definition, high luminance and a wide angle of view while reducing the size of the entire apparatus by appropriately setting each element. It is an object of the present invention to provide an image display device capable of observing images.

[0017]

An image display apparatus according to the present invention illuminates a reflective display element with a light beam from a light source via a light splitting element, and generates a light beam based on display information from the display element. The light is guided to the pupil of the observer through the light splitting element, and two pieces of information, the display information and the image information located in directions different from the display information, are displayed in the same visual field through the light splitting element. It is characterized by observing with.

The image display apparatus according to the second aspect of the present invention illuminates a reflective display element with a light beam from a light source via a light splitting element, and emits a light beam based on display information from the display element via the light splitting element. And the light beam guided by the optical element is guided to the pupil of the observer via the light splitting element to observe the display information.

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

FIG. 1 is a schematic view showing a main part of an image display apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a light source such as a fluorescent lamp. Reference numeral 2 denotes a reflecting plate such as a concave reflecting mirror or an elliptical reflecting mirror, which reflects a light beam emitted backward from the light beam from the light source 1 toward the light splitting element 4. The light splitting element 4 comprises a polarizing beam splitter. Reference numeral 5 denotes a display element, which is a reflection type liquid crystal element in this embodiment. The liquid crystal element 5 is a liquid crystal panel 5a.
And a reflection mirror 6 provided on the back surface of the liquid crystal panel 5a.

In this embodiment, the liquid crystal element 5 is used in the 45 ° TN mode, and the pixel electrode is used as a reflection electrode, thereby also serving as the reflection mirror 6.

Reference numeral 8 denotes a lens system, which is represented by one lens element for simplicity of the drawing, but is actually composed of a plurality of lens elements for aberration correction and the like. Reference numeral 9 denotes a pupil position for observation, which corresponds to an eyeball position of the observer. Reference numeral 10 denotes a virtual image plane of display information on the display element 5 by the lens system 8.

First, the principle of operation of the reflection type liquid crystal element 5 according to the present invention will be described with reference to FIG. The light beam 3 from the light source 1 includes two orthogonally polarized light beams represented by polarized light beams 3-1 and 3-2.

Among them, the polarized light (P-polarized light) 3-1 vibrating in parallel in the paper passes through the polarizing beam splitter 4 and has no relation to image display.

On the other hand, polarized light (S-polarized light) 3-2, 3-3 vibrating vertically (in the plane of the paper), most of which (100%) is reflected by the polarizing beam splitter 4, is a reflection type liquid crystal element 5.
To the liquid crystal panel 5a. Light beam 3-2 incident on a portion 5-11 of the liquid crystal panel 5a where no voltage is applied.
Is reflected by the pixel electrode (reflection mirror) 6 on which the reflection electrode is formed without being modulated on the polarization plane, and the luminous flux (3-2) '
The light enters the polarization beam splitter 4 as S polarized light.

Since the polarization beam splitter 4 reflects the S-polarized light almost (100%), it returns to the light source 1 side and does not reach the pupil 9 of the observer.

Next, the light beam 3-3 incident on the portion 5-12 of the liquid crystal panel 5a to which a voltage is applied is modulated by the polarization plane and reflected to become P-polarized light indicated by the light beam (3-3) '. , And enters the polarization beam splitter 4. This polarization beam splitter 4 transmits almost (100%) the P-polarized light and is guided as a light beam (3-3) "toward the pupil 9 of the observer.

In this embodiment, the display information displayed on the liquid crystal element 5 is observed. The above is the operating principle of the liquid crystal element 5.

Next, the image display device of the present invention shown in FIG. 1 will be described.

A light beam from a light source 1 such as a fluorescent lamp is converted into a substantially parallel light beam 3 by a reflector 2 having an appropriate shape, and is incident on a polarization beam splitter 4. Then, the polarized light incident on the liquid crystal element 5 is modulated only at points (pixels) 5-1, 5-2, 5-3 where an image is displayed according to the principle described above.
Then, the reflected light passes through the polarizing beam splitter 4 as light fluxes 7-1, 7-2, and 7-3 of display information of reflected polarized light having a polarization plane orthogonal to the incident polarized light. These light beams are converted by the lens system 8 into light beams (7-1) ', (7-2)', (7-
3) ′ and enters the pupil 9 of the observer.

At this time, the power of the lens system 8 and the lens position are appropriately set, and the respective light beams (7-1) ', (7)
-2) ', (7-3)' are points (5-1) ', (5-2)', (5-
3) The luminous flux from ′ (7-1) ″, (7-2) ″, (7-
3) ", the display information displayed on the small liquid crystal element 5 is observed as a virtual image on a large screen.

In the reflection type liquid crystal element 5 used in this embodiment, a reflection electrode is arranged on the lower side, and the polarization plane of incident polarized light is modulated according to display information. As a result, the loss in the two polarizing plates (on the entrance side and the exit side), which was necessary in the image display apparatus using the conventional transmission type liquid crystal television, can be reduced.
By arranging the reflective electrode above the TFT, light is not blocked by the TFT, thereby substantially improving the aperture ratio and improving the light use efficiency several times as a whole.

In this embodiment, it is also possible to use a transmissive liquid crystal panel, a reflecting mirror, and a liquid crystal element in which a polarizing plate is arranged between them as the reflective liquid crystal element.
Also in this case, only one polarizing plate needs to be used, so that the light use efficiency is higher than that of the conventional image display device.

Further, in this embodiment, the reflection plate 2 is used to illuminate the reflection type liquid crystal element. However, it is also possible to provide an illumination lens system or to use them in combination.

The polarizing beam splitter 4 and the reflection type liquid crystal element 5 can be directly bonded to each other. Further, when the display information may be a single color, a parallel plate type polarizing beam splitter can be used instead of the cube type polarizing beam splitter used in the present embodiment. It is also possible to use a half mirror instead of using the polarizing beam splitter 4, in which case a polarizing plate may be provided on the light source side and on the liquid crystal element in order to make the parallel components of the illumination light beam 3 uniform.

FIG. 3 is a schematic view of a main part of a second embodiment of the image display device according to the present invention.

In this embodiment, as compared with the first embodiment shown in FIG. 1, of the luminous flux from the illuminating light source 1, the luminous flux transmitted through the polarizing beam splitter 4 is made to enter the reflection type liquid crystal element 5. The points are different, and other configurations are the same.

In FIG. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

The operation principle of the reflection type liquid crystal element 5 in this embodiment will be described with reference to FIG.

The light beam 3 from the light source 1 is polarized light 3-11,3.
It contains two orthogonally polarized lights represented by −12.
Of these, polarized light (S-polarized light) vibrating vertically in the plane of the paper
Most of the light beam 3-11 is reflected by the polarization beam splitter 4 and becomes a light beam (3-11) ', which has no relation to the image display.

On the other hand, polarized light (P-polarized light) 3-1 vibrating in parallel in the plane of the paper transmitted through the polarizing beam splitter 4
2, 3-13 enter the liquid crystal panel 5a of the reflection type liquid crystal element 5.

The light beam 3-12 incident on the portion 5-11 where no voltage is applied on the liquid crystal panel 5a is reflected by the reflection mirror 6 composed of the pixel electrode on which the reflection electrode is formed without being modulated on the polarization plane. And the light flux (3-12) '
The polarized light enters the polarization beam splitter 4 as it is.

Since the polarization beam splitter 4 transmits almost (100%) the P-polarized light, it returns to the light source 1 side and does not reach the pupil 9 of the observer.

Next, the light beam 3-13 incident on the portion 5-12 of the liquid crystal panel 5a to which a voltage is applied is modulated by the polarization plane and reflected, and becomes S-polarized light indicated by the light beam (3-13) '. , And enters the polarization beam splitter 4. The polarization beam splitter 4 reflects the S-polarized light almost (100%), and is guided as a light beam (3-13) "toward the pupil 9 of the observer.

Thus, the display information displayed on the liquid crystal element 5 is observed. The above is the operating principle of the liquid crystal element 5.

Next, the image display device of this embodiment shown in FIG. 3 will be described. A light beam from a light source 1 such as a fluorescent lamp is converted into a substantially parallel light beam 3 by a reflecting plate 2 having an appropriate shape and is incident on a polarizing beam splitter 4. Then, the incident polarized light incident on the liquid crystal element 5 is modulated only at points (pixels) 5-1, 5-2, 5-3 where an image is displayed according to the principle described above. Then, the reflected polarized light is reflected by the polarization beam splitter 4 as light fluxes 7-1, 7-2, and 7-3 of display information of reflected polarized light having a polarization plane orthogonal to the incident polarized light.

These light beams are converted into light beams (7-1) ', (7-2)', and (7-3) 'by the lens system 8, and enter the pupil 9 of the observer. At this time, the power and the lens position of the lens system 8 are appropriately set, and the respective light beams (7-1) ', (7-2)', and (7-3) 'are on the virtual image plane 10 as if they were separated by a predetermined position. Points (5-1) ', (5
-2) ', the light flux (7-1) "from (5-3)', (7
-2) ", (7-3)", so that the image of the small display element 5 is observed as a virtual image of a large screen.

In the figure, reference numeral 31 denotes a liquid crystal shutter or a polarizing plate, which adjusts the voltage applied to the liquid crystal shutter or rotates the polarizing axis of the polarizing plate to adjust the relationship with the polarizing axis of the polarizing beam splitter 4 and thereby adjusts the forward direction. By changing the light transmittance, a display image with good contrast can be observed even when the external luminance is high.

In this embodiment, by disposing the liquid crystal element 5 below the polarizing beam splitter 4, the observer can see the external field in the line of sight through the lens system 8 and the polarizing beam splitter 4, and the brightness of the front is reduced. The front can be seen to the extent that a change is felt or something is approaching, and there is an effect that even if the image display device of the present invention is mounted, a danger ahead can be detected.

FIG. 5 is a schematic view of a main part of a third embodiment of the image display device of the present invention.

In this embodiment, a half mirror 14 is used instead of using the polarizing beam splitter 4 as compared with the first embodiment shown in FIG.
In that a transmissive liquid crystal panel 15 and a reflective mirror 16 are arranged as a reflective liquid crystal element 5 and a polarizing plate 17 is arranged between them, and other configurations are the same. It is.

In FIG. 5, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In FIG. 5, reference numeral 11 denotes a polarizing plate which aligns the polarization components of the illumination light beam 3 from the light source 1 with polarized light (S-polarized light) vibrating vertically in the plane of the drawing. 14 is a half mirror. Reference numeral 15 denotes a transmissive liquid crystal panel, and reference numeral 16 denotes a reflection mirror. Reference numeral 17 denotes a polarizing plate as an analyzer, and the liquid crystal panel 1
5 and the reflection mirror 16.

In this embodiment, a light beam from a light source 1 such as a fluorescent lamp is converted into a substantially parallel light beam 3 by a reflecting plate 2 of an appropriate shape, and a polarization component of the illumination light beam 3 is converted into a vertical direction in FIG. Polarized light (S-polarized light)
Are aligned.

The S-polarized light 13 is split by the half mirror 14
The reflected light beam illuminates the liquid crystal panel 15 (while the transmitted light beam 13 'from the half mirror 14 has nothing to do with image display).

Here, of the S-polarized light incident on the liquid crystal panel 15, the light flux 13-2 incident on a portion of the liquid crystal panel 15 where no voltage is applied is applied to the S-polarized light without being modulated on the polarization plane.
The polarized light is transmitted through the liquid crystal panel 15 and becomes s-polarized (13-
2) ′, which is cut by the polarizing plate 17.

On the other hand, the luminous flux 13-1 incident on the portion 15-1 of the liquid crystal panel 15 to which the voltage is applied is modulated by the polarization plane and transmitted through the liquid crystal panel 15, and the luminous flux (13-
1) 'becomes polarized light (P-polarized light) having a plane of polarization orthogonal to the S-polarized light and transmits through the polarizing plate 17.

The light transmitted through the polarizing plate 17 is reflected by the reflection mirror 16.
, Passes through the polarizing plate 17, modulates the polarization plane by the liquid crystal panel 15, becomes light (13-1) ″ having the same polarization plane as the S-polarized light, passes through the half mirror 14, and is observed by the lens system 8 through the lens system 8 To the pupil 9.

The polarized light incident on the liquid crystal panel 15 is modulated only at a point (pixel) where an image is displayed, becomes a display information light, is reflected, and returns. Thus, the observer observes the display information on the small liquid crystal element 5 as a virtual image of a large screen at a position separated by a predetermined position via the lens system 8.

FIG. 6 is a schematic view of a main part of a fourth embodiment of the image display apparatus according to the present invention.

This embodiment is different from the third embodiment shown in FIG. 5 in that the illumination light flux 3 from the illumination light source 1 is incident on the half mirror 14 at a Brewster angle. Is the same. In the present embodiment, the illumination light flux 3 is obtained by using the polarization dependence of the reflectance at the time of incidence at the Brewster angle (P-polarized light has zero reflectance).
The display with higher brightness than that of the third embodiment can be performed without using the polarizing plate 11 for aligning the polarized light component with the polarized light (S-polarized light) vibrating vertically in the plane of the paper.

In FIG. 6, the same elements as those shown in FIG. 5 are denoted by the same reference numerals.

Next, the embodiment of FIG. 6 will be described focusing on the differences from the embodiment 3 of FIG.

The luminous flux from the light source 1 is applied to a reflecting plate 2 of an appropriate shape.
Incident at the Brewster angle theta _B to the half mirror 14 is converted into substantially parallel light 3 by. The half mirror 14 is made of a simple parallel plate having a refractive index of 1.5, and each surface is not coated with an antireflection film. At this time, the Brewster angle θ _B is about 56 °, and the reflectance of S-polarized light is about 2 °.
At 5.8%, P-polarized light is hardly reflected.

Therefore, the illumination light beam 3 reflected by the half mirror 14 becomes only the polarized light beam 13 of S-polarized light (indicated by reference numeral 12 in the figure) and enters the liquid crystal element 5.

As described above, the S-polarized light, for example, the light beam 13-1, incident on the liquid crystal panel 15 is modulated only at the point (pixel) 15-1 where an image is displayed, and becomes P-polarized light as display information. The light is modulated into the S-polarized light (13-1) ″ at the point 15-1 via the polarizing plate 17, the reflecting mirror 16, and the polarizing plate 17, and is incident on the half mirror 14 again.

The incident angle of the display information light is also substantially Brewster's angle θ _B. The S-polarized light transmittance of the half mirror 14 is about 74.2% (Ts = 1−0.258 = 0.742). For this reason, the S-polarized light (13-1) "transmits through the half mirror 14 at this transmittance, and the pupil 9 of the observer is
Incident on.

In this way, the observer can operate the small liquid crystal element 5.
The above display information is observed as a virtual image of a large screen at a position separated by a predetermined position via the lens system 8.

As described above, in the present embodiment, the half mirror 14
Is used to set the angle so that the luminous flux enters at the Brewster's angle, thereby simplifying the entire device by combining the functions of the two polarizing plates (on the incident side and the exit side) of the liquid crystal element that were required in the past. It is trying to make it.

Next, the light use efficiency of this embodiment and the third embodiment of FIG. 5 will be described.

In the third embodiment shown in FIG. 5, the illumination light beam 3 passes through the polarizing plate 11 having a transmittance of about 40%, and is reflected by the half mirror 14 having a reflectance of 50%.

Now, the reflectance of the entire reflection type liquid crystal element 5 including the liquid crystal panel 15, the polarizing plate 17, and the reflection mirror 16 is represented by R
LCD. This light beam passes through the half mirror 14 again and reaches the pupil 9 of the observer. At this time, assuming that the light intensity of the illumination light beam 3 is I, I × 0.4 × 0.5 × RLCD × 0.5 = 0.10 × RLC
D × I.

On the other hand, in the fourth embodiment, only the necessary S-polarized light of the illumination light beam 3 is filtered by the half mirror 14, and its reflectance is 25.8%. After being reflected by a reflection type liquid crystal element having a reflectance of RLCD, an S-polarized light transmittance of 7
The light passes through the 4.2% half mirror 14 and reaches the pupil 9 of the observer. Therefore, the light use efficiency in the fourth embodiment is I × 0.258 × RLCD × 0.742 = 0.19 × RLC
D × I.

The fourth embodiment achieves approximately twice the light use efficiency as compared with the third embodiment. The half mirror used in the fourth embodiment has a refractive index of 1.
5, a simple parallel plate may be used, and further, a polarizing plate is not required.

FIG. 7 is a schematic view showing a main part of a fifth embodiment of the image display apparatus according to the present invention.

This embodiment is different from the fourth embodiment shown in FIG. 6 in that the parallel light flux 13 from the illumination light source 1 is transmitted through the half mirror 14 once and then is incident on the reflection type liquid crystal element 5. This is different from the first embodiment in that the reflective liquid crystal element 5 has a configuration in which a pixel electrode is a reflective electrode (reflective mirror) 6, and the other configurations are the same.

Next, differences from the fourth embodiment will be mainly described. A light beam from the light source 1 is converted into substantially parallel light 3 by a reflection plate 2 having an appropriate shape, and is incident on a polarizing plate 11. Polarizing plate 1
1 polarization components paper plane parallel polarized light (P polarized light) that vibrates (shown in figure 12) 13 in aligned manner, incident at the Brewster angle theta _B to the half mirror 14. The half mirror 14 is made of a simple parallel plate having a refractive index of 1.5, and each surface is not coated with an antireflection film.

At this time, the Brewster angle θ _B is about 56 °
It is. The P-polarized light 13 transmits almost (100%), and the luminous flux 1
3-1 and 13-2.

The operating principle of the reflection type liquid crystal element 5 in this embodiment is exactly the same as that of FIG. For example, a liquid crystal panel 5a
Only the light beam 13-1 incident on the portion 5-12 to which the voltage is applied above is modulated by the polarization plane and reflected, becomes S-polarized light indicated by the light beam (13-1) ', and is again brewed to the half mirror 14. Incident at the star angle.

At this time, the half mirror 14 changes the S polarization to about 2
Reflect 5.8%. Therefore, the S-polarized light (13-1) 'is reflected by the half mirror 14 and enters the pupil 9 of the observer as a light flux (13-1) ".

As described above, in the present embodiment, the half mirror 14 is used.
Is used in such a manner that the light flux is incident at a Brewster's angle, so that it also has the function of a polarizing plate (analyzer) of the liquid crystal element (on the emission side) which has been conventionally required.

When the light use efficiency in this embodiment is obtained in the same manner as in the above embodiment, the transmittance of the polarizing plate 11 is about 40%, the transmittance of the P-polarized light by the half mirror 14 is 100%, and the liquid crystal panel 5
a 'and the reflective electrode 6 as R'LCD,
If the light intensity of the illumination light beam 3 is I, the reflectance of the S-polarized light, which is image light, at the half mirror 14 is 25.8%, so that I × 0.4 × 1 × R′LCD × 0.258 = 0 .10 ×
R′LCD × I

The reflection type liquid crystal element 5 used in the present embodiment does not require a polarizing plate as compared with the embodiment 4 in FIG. 6, so that its light reflectance is R'LCD> RLCD and the transmittance is about 40%
R ′ LCD = 6.25 R LCD is achieved as compared with Example 4 in FIG. Therefore, the light use efficiency of the present embodiment is approximately 0.625 × RLCD × I, which realizes a higher light use efficiency than the embodiment 4 of FIG.

The reflection type liquid crystal element 5 used in the present embodiment merely arranges a reflection electrode on the lower side and modulates the polarization plane of incident polarized light according to display information. The loss in the two polarizing plates (on the incident side and the output side), which was necessary in the display device used, can be reduced. In addition, by arranging the reflective electrode above the TFT, there is no light blocking by the TFT, and substantial The aperture ratio is improved, and the light use efficiency is improved several times as a whole.

In this embodiment, a liquid crystal shutter or a polarizing plate may be provided at the position 31 in the figure to adjust the transmittance of the external light to adjust the contrast of display information.

In this embodiment, the liquid crystal element 5 is connected to the half mirror 1
4, the observer can see the external field in the line of sight through the lens system 8 and the half mirror 14, and can feel a change in brightness in front, or an object approaching. Has the effect that it is possible to see the front, and even to wear the image display device of the present invention, it is possible to detect the danger ahead.

FIG. 8 is a schematic view of a main part of an image display apparatus according to a sixth embodiment of the present invention. In this embodiment, as compared with the above-described first to fifth embodiments, two pieces of information of display information from the display element 5 and image information Y such as landscapes in the outside world located in directions different from the display information are lighted. The difference is that the images are spatially superimposed via the transmissive light beam coupling element 19 and are observed in the same field of view, and the other configurations are substantially the same.

In FIG. 8, the same elements as those shown in FIG. 1 are denoted by the same reference numerals. In FIG. 8, reference numeral 1 denotes a light source such as a fluorescent lamp. Reference numeral 2 denotes a reflecting plate such as a concave reflecting mirror. Reference numeral 11 denotes a polarizing plate that aligns the polarized light components of the light flux 3 from the light source 1 with polarized light (P-polarized light) 13 that vibrates parallel to the plane of the paper (shown by 12 in the drawing). Reference numeral 5 denotes a reflection type liquid crystal element having a liquid crystal panel 5a and a reflection mirror 6.

In the present embodiment, the liquid crystal element 5 is used in the 45 ° TN mode, and the pixel electrode is used as a reflection electrode to serve also as the reflection mirror 6. Reference numeral 4 denotes a light splitting element, which comprises a polarizing beam splitter. Reference numeral 18 denotes a quarter-wave plate, which converts incident linearly polarized light into circularly polarized light. Reference numeral 19 denotes a light-transmitting light beam coupling element, which is a concave half mirror having a reflectance of about 50% and a transmittance of about 50%.

The concave half mirror 19 has an optically positive power, and its curvature is appropriately set.
The surface of the concave half mirror 19 may be an aspheric surface for correcting aberration, but is described here as a concave surface (spherical surface) for simplicity.

Reference numeral 9 denotes a pupil position for observation, which corresponds to an eyeball position of the observer. Reference numeral 10 denotes a virtual image surface of the display information displayed on the liquid crystal element 5 by the concave half mirror 19, and Y
Is image information such as a natural landscape.

In this embodiment, a light beam from a light source 1 such as a fluorescent lamp is converted into a substantially parallel light beam 3 by a reflection plate 2 having an appropriate shape, and a polarization component is converted by a polarizing plate 11 into a parallel light beam (indicated by 12 in the drawing). To the polarized light (P-polarized light) 13 which is vibrating at the same time. This P-polarized light 13 almost (100%) transmits through the polarization beam splitter 4 and enters the reflection type liquid crystal element 5.

The principle of operation of the reflection type liquid crystal element 5 in this embodiment is exactly the same as that described with reference to FIG.

That is, only the light beam 13-12 incident on the portion 5-12 to which a voltage is applied on the liquid crystal panel 5a is reflected by being modulated by the polarization plane, and is represented by the light beam 13-13.
It becomes polarized light and reenters the polarization beam splitter 4. The display information light composed of the S-polarized light is almost (100%) reflected by the polarization beam splitter 4 and becomes a light flux 13-14. I will

A quarter-wave plate 18 is disposed in the optical path between the polarizing beam splitter 4 and the concave half mirror 19, and converts the display information light 13-14 composed of S-polarized light into circularly polarized light 13-15. Has been converted to.

This display information light is reflected by the concave half mirror 19, passes through the quarter-wave plate 18 again, and
It becomes the polarized display information light 13-16. This display information light 1
Most of the light beams 3-16 pass through the polarizing beam splitter 4 and enter the pupil 9 of the observer.

At this time, by appropriately setting the curvature and the position of the concave half mirror 19, the observer can observe the display image on the small liquid crystal element 5 as a virtual image of a large screen at a place 10 away from the predetermined position. I can do it.

The observer can use the concave half mirror 19 to convert the image information Y such as a natural scenery located in a direction different from the display image displayed on the liquid crystal element 5 into a virtual image of the display image on the liquid crystal element 5. And are observed in the same field of view with spatial overlap.

In this embodiment, the light source 1 and the polarizing beam splitter 4 are provided with a polarizing plate 11 for aligning the polarization component of the light beam 3 with polarized light (P-polarized light) vibrating parallel to the plane of the paper (shown by 12 in the drawing). It may be arranged at 21 immediately before the pupil 9 of the observer instead of between the two.

At that time, polarized light (image information light) 13-1
What is necessary is just to make the polarization axes of the polarizing plate 11 coincide with each other so that 7 is transmitted. By doing so, the S-polarized light unnecessary for the display image in the illumination light 3 is almost reflected by the polarizing beam splitter 4 (even if it is reflected as indicated by 22 in the drawing, it is completely cut by the polarizing plate 21). Does not enter the pupil 9.
Further, at this time, the illumination light 3 transmitted through the polarizing plate 11
This is characterized in that the light amount loss can be suppressed and the display luminance can be increased.

FIG. 9 is a schematic view showing a main part of an image display apparatus according to a seventh embodiment of the present invention.

This embodiment is different from the sixth embodiment in FIG. 8 in that a half mirror is used instead of using the polarizing beam splitter 4 and that the illumination light 13 from the illumination light source 1 is transmitted to the half mirror 14 by the Brewster angle. θ that is incident is different in _B, and other configurations are the same.

In FIG. 9, the same elements as those shown in FIG. 8 are denoted by the same reference numerals.

In this embodiment, a light beam from a light source 1 such as a fluorescent lamp is converted into a substantially parallel light beam 3 by a reflection plate 2 of an appropriate shape, and a polarization component is converted into a parallel light beam by a polarizing plate 11 (12 in the drawing).
(Illustrated in FIG. 3) are aligned with the polarized light (P-polarized light) 13 oscillating. The P-polarized light 13 is incident at the Brewster angle theta _B to the half mirror 14. The half mirror 14 is made of a simple parallel plate having a refractive index of 1.5, and each surface is not coated with an antireflection film. At this time, the Brewster angle θ _B is about 56 °, and the P-polarized light 13 is almost (100%).
Transmitted.

The operating principle of the reflection type liquid crystal element 5 in this embodiment is exactly the same as that described with reference to FIG. That is, only the light beam 13-11 incident on the portion 5-12 to which a voltage is applied on the liquid crystal panel 5a is modulated by the polarization plane and reflected, becomes S-polarized light indicated by the light beam 13-13, and is again transmitted to the half mirror 14. Incident at Brewster's angle.

At this time, the half mirror 14 changes the S polarization to about 2
The light is reflected by 5.8%, and is guided as a light flux 13-14 in the direction of the concave half mirror 19 placed at a position facing the pupil 9 of the observer.

The display information light 13-14 is reflected by the concave half mirror 19 and enters the half mirror 14 as a light flux 13-18 at a Brewster angle θ _B. At this time, the transmittance of the S-polarized light at the Brewster's angle is 74.2.
%. Therefore, the S-polarized light 13-18 passes through the half mirror 14 at this transmittance and enters the pupil 9 of the observer.

Also in this embodiment, the observer moves the display image on the small liquid crystal element 5 at a predetermined position by appropriately setting the curvature and the position of the concave half mirror 19 as in the sixth embodiment of FIG. A large image can be observed at the place 10 as a virtual image.

The observer can use the concave half mirror 19 to convert the image information Y such as a natural scenery located in a direction different from the display image displayed on the liquid crystal element 5 into a virtual image of the display image on the liquid crystal element 5. And are observed in the same field of view with spatial overlap.

In each of the above embodiments 6 and 7, two observation systems may be prepared, display information having parallax may be given to the liquid crystal element 5, and observation may be made with the right and left eyes of the observer. According to this, it is possible to observe display information having a three-dimensional effect.

[0124]

As described above, according to the present invention, a reflective liquid crystal element having a suitable structure is used as a display element, and the overall size of the apparatus is reduced by appropriately setting each element. It is possible to achieve an image display device which is capable of observing a wide angle of view with high definition and high luminance.

[0125]

[0126]

In particular, when both the display information of the liquid crystal element and the image information such as the external scenery are observed in the same field of view, the display brightness is high. As a result, the display information with high contrast can be superimposed and observed. An image display device can be achieved.

[Brief description of the 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 the operation principle of the liquid crystal element of FIG.

FIG. 3 is a schematic diagram of a main part of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation principle of the liquid crystal element of FIG.

FIG. 5 is a schematic view of a main part of a third embodiment of the present invention.

FIG. 6 is a schematic diagram of a main part of a fourth embodiment of the present invention.

FIG. 7 is a schematic diagram of a main part of a fifth embodiment of the present invention.

FIG. 8 is a schematic diagram of a main part of a sixth embodiment of the present invention.

FIG. 9 is a schematic view of a main part of a seventh embodiment of the present invention.

FIG. 10 is a schematic view of a main part of a conventional image display device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light source 2 reflector 3 illumination light beam 4, 14 light splitting element 5 liquid crystal element 5 a liquid crystal panel 6, 16 reflection mirror 11, 17 polarizing plate 8 lens system 9 observer's pupil 10 virtual image plane 18 λ / 4 19 light flux coupling element Y Image information

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-150117 (JP, A) JP-A-4-366925 (JP, A) JP-A-3-200137 (JP, A) JP-A-4-200 221920 (JP, A) JP-A-3-203478 (JP, A) JP-A-4-225388 (JP, A) U.S. Pat. No. 5,810,131 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB G02B 27/02 G02F 1/13 505 G02F 1/1335 520 H04N 5/64 511 G03B 21/132

Claims (2)

(57) [Claims] A light source illuminates a reflective display element via a light splitting element with a light flux from a light source, and guides a light flux based on display information from the display element to an observer's pupil via the light splitting element. An image display apparatus characterized by observing two pieces of information of the display information and image information located in directions different from the display information in the same field of view via the light splitting element. 2. A light source from a light source illuminates a reflective display element via a light splitting element, and a light flux based on display information from the display element is guided to the optical element via the light splitting element.
An image display device, wherein a light beam that has been subjected to an optical action by the optical element is guided to an observer's pupil via the light splitting element, and the display information is observed.