JPH07128614A - Image display device - Google Patents

Abstract

PURPOSE:To enhance the fineness and luminance of the device while reducing the size over the entire part thereof and to enable observation at a wide visual angle by constituting a display element of a liquid crystal element of a reflection type at the time of macroobserving display information as a virtual image. CONSTITUTION:The display element 5 consists of the liquid crystal element of the reflection type. The luminous fluxes from a light source 1 of a fluorescent lamp are converted to approximate parallel luminous fluxes 3 by a reflection plate 2 of a proper shape. These fluxes are made incident on a polarization beam splitter 4. Further, the incident polarized light beams on the liquid crystal element 5 are modulated only at the points 5-1 to 5-3 where the images are displayed. The incident polarized light beams pass the polarization beam splitter 4 as the luminous fluxes 7-1 to 7-3 of the display information of the reflected polarized light having the orthogonal planes of polarization. These luminous fluxes are converted by the lens system 8 to the luminous fluxes (7-1)' to (7-3)' which are made incident on the observer's pupils 9. At this time, observer feels as if he views the luminous fluxes (7-1)'' to (7-3)'' from the points (5-1)' to (5-3)' on the virtual image plane 10. The observer is thus able to observe the display information displayed on the small-sized liquid crystal element 5 as the virtual image of a large screen.

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 optical system having a small image information (display information) such as a liquid crystal device, which is installed in front of an observer's head or face. The present invention relates to an image display device that is observed as a virtual image with 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 device such as a liquid crystal as an image of a large screen with a sense of reality. Has been.

These image display devices require a large space, and when they are installed in a small room, there are problems that an appropriate viewing distance cannot be secured, and that individual persons cannot watch different programs. It was

Therefore, for example, in Japanese Laid-Open Patent Publication No. 3-203478, for example, as shown in FIG. 10, the optical system in which the light flux from the image display element is arranged near the observer's face is directly used to directly observe the eyes (the observer's pupil). We have proposed an image display device that guides light to the screen to observe image information on a large screen.

The main part of FIG.
221L is 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 (222L (not shown)) arranged in front of both eyes and is incident on the front concave mirror 223. To 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).

As a result, the observer sees the LCD 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.

Further, in such an image display device, it is possible to display stereoscopic images by displaying display information having parallax for the right eye and the left eye of the observer.

Further, in JP-A-4-221920, the image displayed on the polarized light control type display is magnified by a convex lens, and the polarized image is observed by the polarization spectroscopic means arranged in front of the observer's pupil. There is proposed an image display device capable of displaying the enlarged virtual image by superimposing it on the outside by making it enter the pupil.

[0009]

In a conventional image display device, a color television or a polarized light control type display used as a display element uses a transmissive liquid crystal element illuminated by a backlight.

For example, in a TFT liquid crystal color television as a liquid crystal element, the liquid crystal panel of the current product level has a low aperture ratio of about 40% and cannot obtain a sufficient transmittance. Therefore, in order to achieve sufficient display brightness, it is necessary to increase the light amount of the backlight and to provide a sheet-shaped multi-lens array in the opening, which hinders the reduction in size and weight of the entire device. . Also, it is difficult to reduce power consumption because a large backlight is required.

There are various factors that reduce the aperture ratio of the liquid crystal element. The TFT, the wiring, the auxiliary capacitance,
The main part is the black matrix portion on the color filter that covers these gaps. Therefore TF
The aperture ratio has been improved by reducing the dimension of T and wiring, and reducing the area of the auxiliary capacitance.

However, these methods are problematic because they are limited by the restrictions of the semiconductor process technology such as the TFT process.

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

In order to solve this, there is a method of increasing the density of pixels of the liquid crystal panel. This method has a problem that the higher the density, the more elements such as TFTs and wirings and the lowering of the aperture ratio.

In addition, the transmission type liquid crystal television requires two polarizing plates arranged in a crossed Nicols state, which also causes a reduction in display brightness.

The present invention uses a reflection type liquid crystal element having an appropriate structure as a display element, and appropriately sets each element to reduce the size of the entire device, while providing high definition, high brightness and a wide angle of view. It is an object of the present invention to provide an image display device capable of observing.

[0017]

The image display device according to the present invention comprises: (1-1) guiding a luminous flux based on display information from a display element to an observer's pupil through an optical system to display the display information. It is characterized in that the display element is composed of a reflection type liquid crystal element when magnified and observed as a virtual image.

In particular, (1-1-1) a light splitting element is arranged in an optical path between the display element and an observer, and the display element is provided with a light beam from a light source through the light splitting element. Be illuminated with.

(1-1-2) The optical system is arranged between the light splitting means and an observer.

(1-1-3) The light beam from the light source passes through a polarizing plate that allows only predetermined polarized light to pass and is incident on the light splitting element. And so on.

(1-2) Display information from the display element and image information located in a direction different from that of the display information.
When two pieces of information are spatially overlapped via a light transmissive light flux coupling element and observed in the same visual field, the display element is constituted by a reflective liquid crystal element.

In particular, (1-2-1) a light splitting element is arranged in an optical path between the display element and an observer, and the display element is provided with a light beam from a light source through the light splitting element. Be illuminated with.

(1-2-2) The light source passes through a polarizing plate that allows only predetermined polarized light to pass through and enters the light splitting element.

(1-2-3) A polarizing plate is arranged in the optical path between the light splitting element and the observer's pupil to allow only predetermined polarized light to pass therethrough.

(1-2-4) The predetermined polarized light from the light source passes through the light splitting element and is incident on the liquid crystal element, and the display information light reflected and modulated by the liquid crystal element is reflected. The light splitting element reflects the light in the direction of the light flux coupling element, and the display information light reflected by the light flux coupling element is transmitted through the light splitting element again to be incident on an observer's pupil.

(1-2-5) A quarter wavelength plate is arranged in the optical path between the light splitting element and the light beam coupling element.

(1-2-6) The light beam coupling element has an optically positive refracting power. And so on.

In addition, in the image display device of the present invention,
(1-3-1) The light splitting element is a polarization beam splitter.

(1-3-2) The light splitting element is a half mirror, and the light from the light source is incident on the half mirror at a Brewster's angle.

(1-3-3) The liquid crystal element has a pixel electrode as a reflective electrode.

(1-3-4) The liquid crystal element has a transmissive liquid crystal panel, a reflection mirror, and a polarizing plate arranged between them. And so on.

[0032]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of an image display device of the present invention.

Reference numeral 1 in the figure denotes a light source such as a fluorescent lamp. Reference numeral 2 denotes a reflecting plate such as a concave reflecting mirror or an elliptic reflecting mirror, which reflects the light beam emitted from the light source 1 and emitted backward, toward the light splitting element 4. The light splitting element 4 is composed of a polarization beam splitter. Reference numeral 5 denotes a display element, which is a reflective 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 serves as a reflection electrode, so that the reflection mirror 6 also serves as the reflection electrode 6.

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

First, the operation principle of the reflective liquid crystal element 5 according to the present invention will be described with reference to FIG. The light flux 3 from the light source 1 includes two orthogonal polarized lights represented by polarized lights 3-1 and 3-2.

Of these, the polarized light (P-polarized light) 3-1 vibrating parallel to the paper surface passes through the polarizing beam splitter 4 and has nothing to do with image display.

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

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

Then, the light beam 3-3 that has entered the portion 5-12 to which a voltage is applied on the liquid crystal panel 5a is modulated by the polarization plane and reflected, and becomes P-polarized light shown by the light beam (3-3) '. , Enters the polarization beam splitter 4. The polarization beam splitter 4 transmits almost (100%) P-polarized light and guides it as a light beam (3-3) ″ toward the observer's pupil 9.

In this embodiment, the display information displayed on the liquid crystal element 5 is observed. The above is the operation 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 reflecting plate 2 having an appropriate shape, and enters a polarization beam splitter 4. Then, the polarized light incident on the liquid crystal element 5 is modulated only at the points (pixels) 5-1, 5-2, 5-3 where the image is displayed according to the above-described principle.
Then, the light beams 7-1, 7-2, and 7-3 of display information of reflected polarized light having a polarization plane orthogonal to the incident polarized light are transmitted through the polarization beam splitter 4. The light fluxes (7-1) ', (7-2)', (7-
3) ′ and is incident on the observer's pupil 9.

At this time, the power of the lens system 8 and the lens position are appropriately set, and the respective luminous fluxes (7-1) 'and (7
-2) ', (7-3)' are points (5-1) ', (5-2)', (5-
3) 'from the luminous flux (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.

The reflective liquid crystal element 5 used in this embodiment has a reflective electrode arranged on the lower side, and modulates the plane of polarization of incident polarized light according to display information. As a result, it is possible to reduce the loss in the two polarizing plates (on the incident side and the emitting side), which is necessary in the conventional image display device using the transmissive liquid crystal television.
By arranging the reflective electrode above the TFT, the light shielding by the TFT is eliminated, and thereby the substantial aperture ratio is improved and the light utilization efficiency is improved several times as a whole.

Further, in the present embodiment, it is also possible to use a transmissive liquid crystal panel, a reflective 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, since only one polarizing plate needs to be used, the light utilization efficiency is higher than that of the conventional image display device.

Further, in the present embodiment, the reflector 2 is used to illuminate the reflection type liquid crystal element, but it is also possible to provide an illumination lens system or to use a combination of these.

It is also possible to directly attach the polarization beam splitter 4 and the reflection type liquid crystal element 5. Further, when the display information may be a single color, a parallel plate type polarization beam splitter may be used instead of the cube type polarization beam splitter used in this embodiment. It is also possible to use a half mirror instead of using the polarization beam splitter 4, and in that case, a polarizing plate may be provided on the light source side and on the liquid crystal element in order to align the parallel components of the illumination light beam 3.

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

In this embodiment, as compared with the first embodiment shown in FIG. 1, of the light fluxes from the illumination light source 1, the light fluxes transmitted through the polarization beam splitter 4 are made to enter the reflective liquid crystal element 5. The difference is that the other configurations are the same.

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

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

The light flux 3 from the light source 1 is polarized light 3-11, 3
It includes two orthogonal polarized lights represented by −12.
Of these, polarized light that vibrates vertically in the plane of the paper (S-polarized light)
Almost all of 3-11 is reflected by the polarization beam splitter 4 and becomes a light flux (3-11) ', which has nothing to do with image display.

On the other hand, polarized light (P-polarized light) 3-1 that has been transmitted through the polarization beam splitter 4 and is vibrating parallel to the plane of the paper
2 and 3-13 are incident on the liquid crystal panel 5a of the reflective liquid crystal element 5.

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

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

Next, the light beam 3-13 that has entered the portion 5-12 to which a voltage is applied on the liquid crystal panel 5a is modulated by the polarization plane and reflected, and becomes the S-polarized light shown by the light beam (3-13) '. , Enters the polarization beam splitter 4. The polarization beam splitter 4 reflects almost (100%) S-polarized light and guides it as a light flux (3-13) ″ toward the observer's pupil 9.

Thereby, the display information displayed on the liquid crystal element 5 is observed. The above is the operation 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 enters a polarization beam splitter 4. The incident polarized light that has entered the liquid crystal element 5 according to the above-described principle is modulated only at the points (pixels) 5-1, 5-2, 5-3 where the image is displayed. Then, the light beams 7-1, 7-2, and 7-3 of display information of reflected polarized light having a polarization plane orthogonal to the incident polarized light are reflected by the polarization beam splitter 4.

These light fluxes are converted into light fluxes (7-1) ', (7-2)', (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 so that the respective luminous fluxes (7-1) ′, (7-2) ′, (7-3) ′ are on the virtual image plane 10 separated by a predetermined position. Point (5-1) ', (5
-2) ', (5-3)' and luminous fluxes (7-1) ", (7
-2) ", (7-3)" as if the user is looking at the image of the small display element 5 as a virtual image on a large screen.

Reference numeral 31 in the drawing denotes a liquid crystal shutter or a polarizing plate, which is adjusted by adjusting the voltage applied to the liquid crystal shutter or rotating the polarizing axis of the polarizing plate to adjust the relationship with the polarizing axis of the polarizing beam splitter 4. By changing the light transmittance of, the display image with good contrast is observed even if the external brightness is high.

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

FIG. 5 is a schematic view of the essential portions of Embodiment 3 of the image display device of the present invention.

In this embodiment, as compared with the first embodiment shown in FIG. 1, instead of using the polarization beam splitter 4, a half mirror 14 is used.
2 is different from that of FIG. 1 in that a transmissive liquid crystal panel 15 and a reflective mirror 16 are provided as the reflective liquid crystal element 5, and a polarizing plate 17 is arranged between them. Is.

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

In FIG. 5, reference numeral 11 denotes a polarizing plate, which aligns the polarization component of the illumination light beam 3 from the light source 1 with the polarized light (S-polarized light) vibrating vertically in the plane of the drawing. 14 is a half mirror. Reference numeral 15 is a transmissive liquid crystal panel, and 16 is a reflection mirror. Reference numeral 17 denotes a polarizing plate as an analyzer, which is a 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 reflection plate 2 having an appropriate shape, and a polarization component of the illumination light beam 3 is perpendicular to the plane of the drawing by a polarizing plate 11 (in the figure). Polarized light vibrating in 12) (S polarization)
Are available.

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

Here, of the S-polarized light that has entered the liquid crystal panel 15, the light flux 13-2 that has entered the portion of the liquid crystal panel 15 to which no voltage has been applied is S-polarized without being modulated.
The polarized light is transmitted through the liquid crystal panel 15 as it is and the S-polarized light (13-
2) ′ and is cut by the polarizing plate 17.

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

The light transmitted through the polarizing plate 17 is reflected by the reflecting mirror 16.
The light is reflected by the polarizing plate 17, passes through the polarizing plate 17, the polarization plane is modulated by the liquid crystal panel 15, becomes light (13-1) ″ having the same polarization plane as the S-polarized light, and passes through the half mirror 14 to be observed by the lens system 8. Is incident on the pupil 9 of.

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

FIG. 6 is a schematic view of the essential portions of Embodiment 4 of the image display apparatus of the present invention.

The present embodiment is different from the third embodiment in FIG. 5 in that the illumination light flux 3 from the light source 1 for illumination is made incident on the half mirror 14 at the Brewster angle, and other configurations are provided. Are the same. In the present embodiment, the illumination light flux 3 is obtained by using the polarization dependence of the reflectance when incident at Brewster's angle (P-polarized light has a reflectance of zero).
The high-brightness display is possible as compared with the third embodiment without using the polarizing plate 11 for aligning the polarized light component of (1) with the polarized light (S-polarized light) vibrating vertically in the plane of the drawing.

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

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

The light beam from the light source 1 has a reflection plate 2 having an appropriate shape.
Is converted into substantially parallel light 3 by and is incident on the half mirror 14 at a Brewster angle θ _B. The half mirror 14 is composed 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 flux 3 reflected by the half mirror 14 becomes only the polarized light flux 13 of S polarization (shown by 12 in the figure) and enters the liquid crystal element 5.

As described above, the S-polarized light that has entered the liquid crystal panel 15, for example, the light flux 13-1 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 S-polarized light (13-1) ″ at a 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 approximately 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). Therefore, the S-polarized light (13-1) ″ is transmitted through the half mirror 14 at this transmittance, and the lens system 8 causes the pupil 9 of the observer to enter.
Incident on.

In this way, the observer sees the small liquid crystal element 5
The display information above 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 this embodiment, the half mirror 14 is used.
Is used by setting the angle so that the light beam is incident at Brewster's angle, the function of the two polarizing plates (on the incident side and the emission side) of the liquid crystal element, which was required in the past, is combined and the entire device is simplified. Is trying to

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 reflective liquid crystal element 5 including the liquid crystal panel 15, the polarizing plate 17, and the reflection mirror 16 is R.
LCD. This light flux again passes through the half mirror 14 and reaches the pupil 9 of the observer. At this time, when the light intensity of the illumination luminous flux 3 is I, I × 0.4 × 0.5 × RLCD × 0.5 = 0.10 × RLC
It is D × I.

On the other hand, in the fourth embodiment, only the S-polarized light required for the illumination light flux 3 is filtered by the half mirror 14, and the reflectance thereof is 25.8%. After being reflected by the reflective liquid crystal element having the reflectance of RLCD, the S-polarized light transmittance 7
The light passes through 4.2% of the half mirror 14 and reaches the pupil 9 of the observer. Therefore, the light utilization efficiency in Example 4 is I × 0.258 × RLCD × 0.742 = 0.19 × RLC
It becomes D × I.

The light utilization efficiency of the fourth embodiment is about twice that of the third embodiment. The half mirror used in Example 4 has a refractive index of 1.
The simple parallel plate of No. 5 is sufficient, and the polarizing plate is not necessary. Therefore, the cost of the entire apparatus can be reduced.

FIG. 7 is a schematic view of the essential portions of Embodiment 5 of the image display device of the present invention.

Compared to the fourth embodiment shown in FIG. 6, the present embodiment is configured so 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 reflective liquid crystal element 5. The difference is that the liquid crystal element 5 of the reflection type has a structure in which a pixel electrode is a reflection electrode (reflection mirror) 6, and the other structures 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
The polarized light component is aligned with the polarized light (P-polarized light) 13 vibrating in parallel (indicated by 12 in the drawing) in the plane of paper by 1 and is incident on the half mirror 14 at the Brewster angle θ _B. The half mirror 14 is composed 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 °.
Is. Almost (100%) of the P-polarized light 13 is transmitted, and the luminous flux 1
3-1 and 13-2.

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

At this time, the half mirror 14 converts the S-polarized light into about 2
Reflects 5.8%. Therefore, the S-polarized light (13-1) 'is reflected by the half mirror 14 and enters the observer's pupil 9 as a light flux (13-1) ".

As described above, in this embodiment, the half mirror 14 is used.
Is used by setting the angle so that the light beam enters at Brewster's angle, it also functions as a polarizing plate (analyzer) of the liquid crystal element (on the exit 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 P polarized light transmittance of the half mirror 14 is 100%, and the liquid crystal panel 5 is used.
Let R'LCD be the total reflectance consisting of a and the reflective electrode 6,
Assuming that the light intensity of the illumination luminous flux 3 is I, the reflectance of the S-polarized light that is the image light on the half mirror 14 is 25.8%, so I × 0.4 × 1 × R′LCD × 0.258 = 0 10 ×
R'LCD x I.

Since the reflective liquid crystal element 5 used in this embodiment does not require a polarizing plate as compared with the embodiment 4 of FIG. 6, its light reflectance is R'LCD> RLCD and its transmittance is about 40%
R'LCD = 6.25RLCD is achieved as compared with the fourth embodiment shown in FIG. Therefore, the light use efficiency of this embodiment is approximately 0.625 × RLCD × I, and the light use efficiency is higher than that of the fourth embodiment shown in FIG.

The reflection type liquid crystal element 5 used in this embodiment has a reflection electrode disposed on the lower side and only modulates the plane of polarization of incident polarized light according to display information. In the display device used, the loss in the two polarizing plates (on the incident side and the emitting side), which is necessary, can be reduced, and by disposing the reflective electrode above the TFT, light shielding by the TFT is eliminated, and The aperture ratio is improved and the light utilization efficiency is improved several times as a whole.

In this embodiment, it is also possible to adjust the contrast of the display information by providing a liquid crystal shutter or a polarizing plate at the position 31 in the figure to adjust the transmittance of light in the external environment.

In this embodiment, the liquid crystal element 5 is replaced by the half mirror 1.
By arranging it below 4, the observer can see the external world in the direction of the line of sight through the lens system 8 and the half mirror 14, and feel the change in the brightness in the front, or get closer to something. Has the effect of being able to see the front and to be able to detect the danger ahead even when the image display device of the present invention is attached.

FIG. 8 is a schematic view of the essential portions of Embodiment 6 of the image display device of the present invention. In this embodiment, as compared with the above-described first to fifth embodiments, the display information from the display element 5 and two pieces of information such as image information Y such as a landscape of the outside world located in a different direction from the display information are optically transmitted. They are different in that they are spatially overlapped via a transmissive light beam coupling element 19 and are observed in the same visual field, and the other configurations are substantially the same.

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

In this embodiment, the liquid crystal element 5 is used in the 45 ° TN mode, and the pixel electrode serves as a reflective electrode, so that the liquid crystal element 5 also serves as the reflective mirror 6. Reference numeral 4 denotes a light splitting element, which is composed of a polarization beam splitter. Reference numeral 18 is a quarter-wave plate that converts incident linearly polarized light into circularly polarized light. Reference numeral 19 denotes a light transmissive light flux 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 optical positive power and its curvature is set appropriately.
Although the surface of the concave half mirror 19 may be an aspherical surface for aberration correction, it will be described here as a concave surface (spherical surface) to simplify the description.

Reference numeral 9 is a pupil position for observation, which corresponds to the eyeball position of the observer. Reference numeral 10 represents a virtual image plane of the display information displayed on the liquid crystal element 5 by the concave half mirror 19.
Is image information such as natural scenery.

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 polarizing component 11 makes a polarization component parallel to the plane of the paper (indicated by 12 in the figure). The polarized light (P-polarized light) 13 vibrating in the direction is aligned. The P-polarized light 13 is almost (100%) transmitted through the polarization beam splitter 4 and is incident on the reflective liquid crystal element 5.

The operation principle of the reflective 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 which is incident on the portion 5-12 to which the voltage is applied on the liquid crystal panel 5a is modulated by the polarization plane and reflected, and S indicated by the light beam 13-13 is shown.
It becomes polarized light and enters the polarization beam splitter 4 again. Almost (100%) of the S-polarized display information light is reflected by the polarization beam splitter 4 and becomes a light beam 13-14, which is guided to the concave half mirror 19 located at a position facing the observer's pupil 9. Get burned.

A quarter-wave plate 18 is arranged in the optical path between the polarization beam splitter 4 and the concave half mirror 19, and the display information light 13-14 of S polarization is circularly polarized 13-15. Is converted to.

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

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

Also, the observer receives the virtual image of the display image of the liquid crystal element 5 through the concave half mirror 19 through the image information Y of the natural scenery or the like which is located in the direction different from the display image displayed on the liquid crystal element 5. And spatially overlap with each other and observe in the same field of view.

In this embodiment, the light source 1 and the polarization beam splitter 4 are provided with a polarizing plate 11 for aligning the polarization component of the light flux 3 into polarized light (P-polarized light) oscillating parallel to the plane of the paper (shown by 12 in the figure). It may be arranged 21 in front of the observer's pupil 9 instead of in the space.

In that case, polarized light (image information light) 13-1
It suffices that the polarization axes of the polarizing plate 11 be aligned so that 7 is transmitted. By doing so, the S-polarized light that is unnecessary for the display image in the illumination light 3 is almost reflected by the polarization beam splitter 4 (even if it is reflected as shown by 22 in the figure, it is all cut by the polarizing plate 21). It does not enter the pupil 9.
Further, at this time, the illumination light 3 by passing through the polarizing plate 11
The advantage is that the loss of light amount can be suppressed and the display brightness can be increased.

FIG. 9 is a schematic view of the essential portions of Embodiment 7 of the image display device of the present invention.

In this embodiment, a half mirror is used instead of the polarization beam splitter 4 in comparison with the sixth embodiment of FIG. 8, and the illumination light 13 from the light source 1 for illumination is transmitted to the half mirror 14 at the Brewster angle. The incident point is different at θ _B , and the other configurations are the same.

In FIG. 9, the same elements as those shown in FIG. 8 are designated 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 reflecting plate 2 having an appropriate shape, and a polarizing component 11 makes a polarized component parallel to the plane of the paper (12 in the figure).
The polarized light (P-polarized light) 13 vibrating (shown in FIG. The P-polarized light 13 is incident on the half mirror 14 at a Brewster angle θ _B. The half mirror 14 is composed 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%).
Is transparent.

The operating principle of the reflective 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 the voltage is applied on the liquid crystal panel 5a is modulated by the polarization plane and reflected, and becomes the S-polarized light shown by the light beam 13-13, and is reflected again on the half mirror 14. Incident at Brewster's angle.

At this time, the half mirror 14 outputs about 2 S-polarized light.
It is reflected by 5.8% and is guided as a light beam 13-14 toward the concave half mirror 19 placed at a position facing the observer's pupil 9.

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

Also in this embodiment, similarly to the embodiment 6 of FIG. 8, the observer separates the display image on the small liquid crystal element 5 by a predetermined position by appropriately setting the curvature and the position of the concave half mirror 19. A virtual image on a large screen can be observed at the place 10.

Further, the observer receives the virtual image of the display image of the liquid crystal element 5 through the concave half mirror 19 through the image information Y of the natural scenery or the like which is located in the direction different from the display image displayed on the liquid crystal element 5. And spatially overlap with each other and observe in the same field of view.

In each of the above-described Examples 6 and 7, two observation systems may be prepared to provide the liquid crystal element 5 with display information having parallax so that the right eye and the left eye of each observer can observe. According to this, it is possible to observe display information having a stereoscopic effect.

[0124]

As described above, according to the present invention, a reflective liquid crystal element having an appropriate structure is used as a display element, and by appropriately setting each element, it is possible to reduce the size of the entire device and increase the size. It is possible to achieve an image display device that enables observation with high definition and high brightness and a wide angle of view.

In particular, it is possible to achieve an image display device capable of high-definition display while maintaining a sufficient aperture ratio.

In addition to this, according to the present invention, a polarization beam splitter is used, and the incident angle of the illumination light to the half mirror is set to the Brewster angle. It becomes possible to display.

In particular, when both the display information of the liquid crystal element and the image information such as the scenery of the outside world are observed in the same field of view, the display brightness is high, and as a result, the display information of high contrast can be superimposed and observed. . Further, by setting the half mirror to Brewster's angle, the half mirror is a mere parallel plate, and the antireflection film may not be coated, and still has a feature that high display brightness can be achieved. An image display device can be achieved.

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

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

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

FIG. 5 is a schematic view of the essential portions of Embodiment 3 of the present invention.

FIG. 6 is a schematic view of the essential portions of Embodiment 4 of the present invention.

FIG. 7 is a schematic view of the essential portions of Embodiment 5 of the present invention.

FIG. 8 is a schematic view of the essential portions of Embodiment 6 of the present invention.

FIG. 9 is a schematic view of the essential portions of Embodiment 7 of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 reflection plate 3 illumination luminous flux 4,14 light splitting element 5 liquid crystal element 5a 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 luminous flux coupling element Y Image information

Claims (16)

[Claims] 1. When a light flux based on display information from a display element is guided to an observer's pupil through an optical system and the display information is magnified and observed as a virtual image, the display element is formed by a reflective liquid crystal element. An image display device characterized by being configured. 2. A light splitting element is arranged in an optical path between the display element and an observer, and the display element is illuminated with a light beam from a light source via the light splitting element. The image display device according to claim 1. 3. The image display device according to claim 2, wherein the optical system is arranged between the light splitting means and an observer. 4. The image display device according to claim 2, wherein the light beam from the light source passes through a polarizing plate that allows only predetermined polarized light to pass and is incident on the light splitting element. 5. The display information from the display element and the two pieces of image information, which are image information located in different directions from the display information, are spatially overlapped via the light transmissive light beam coupling element to be the same. An image display device characterized in that the display element is composed of a reflective liquid crystal element when observed in a visual field. 6. A light splitting element is arranged in an optical path between the display element and an observer, and the display element is illuminated with a light beam from a light source via the light splitting element. The image display device according to claim 5, which is characterized in that. 7. The image display device according to claim 6, wherein the light source passes through a polarizing plate that allows only predetermined polarized light to pass through and enters the light splitting element. 8. The image display device according to claim 6, further comprising a polarizing plate disposed in the optical path between the light splitting element and the observer's pupil to allow only predetermined polarized light to pass therethrough. 9. A predetermined polarized light from the light source is passed through the light splitting element to enter the liquid crystal element, and the display information light which is modulated by the liquid crystal element and reflected by the light splitting element is output by the light splitting element. 8. The image display according to claim 7, wherein the light is reflected in the direction of the light beam coupling element, the display information light reflected by the light beam coupling element is transmitted through the light splitting element again, and is incident on the pupil of the observer. apparatus. 10. The image display device according to claim 9, wherein a quarter-wave plate is arranged in an optical path between the light splitting element and the light beam coupling element. 11. The image display device according to claim 5, wherein the light beam coupling element has an optically positive refractive power. 12. The image display device according to claim 2, wherein the light splitting element is a polarization beam splitter. 13. The image display device according to claim 2, wherein the light splitting element is a half mirror. 14. The image display device according to claim 13, wherein the light from the light source is incident on the half mirror at a Brewster's angle. 15. The liquid crystal element according to claim 1, wherein the pixel electrode is a reflective electrode.
Image display device of paragraph. 16. The liquid crystal device according to claim 1, wherein the liquid crystal device has a transmissive liquid crystal panel, a reflection mirror, and a polarizing plate arranged between them.
Image display device of paragraph.