JPH04353818A - Stereoscopic image display device - Google Patents

Abstract

PURPOSE:To offer the stereoscopic image display device which is small-sized, lightweight, simple, and low in cost without the need to remodel LCDs and their driving system and alter their designs. CONSTITUTION:At the projection positions of LCDs 11 and 12, 1/4-wavelength plates 13 and 14 are arranged as circular polarizing means so as to employ the same structures of the LCDs and their driving system for the LCDs 11 and 12 for a left and a right parallax image. One of the projection circular polarized light beams of the 1/4-wavelength plates 13 and 14 is reflected and the other is transmitted; and the both are put together and their circular polarizing directions become opposite at this time. The composite light is observed through observation spectacles 16 formed by a 1/4-wavelength plate 17 and linear polarizing plates 18a and 18b which have orthogonal linear polarizing directions, so that a stereoscopic image is displayed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a three-dimensional image display device, in particular, a system for observing circularly polarized light images modulated by left and right parallax images and having different rotation directions on the left and right sides through a circular polarization analyzer. The present invention relates to a three-dimensional image display device that displays a three-dimensional image by allowing a person to observe it with the left and right eyes of a person.

0002

[Prior Art] As is well known, the principle of stereoscopic imaging is that the left and right visual fields of an observer are separated, and images with parallax for the right eye and left eye are created in the left and right visual fields of the observer, respectively. By making it incident, a three-dimensional image can be observed.

[0003] As a method for separating images for the right eye and for the left eye, the left and right images have different colors, and glasses are used that are equipped with light-transmitting materials colored in complementary colors as the left and right lenses, respectively. Although this method has been known for a long time, it cannot handle color images.

As a method for separating left and right images to obtain a color stereoscopic image, a method is known in which the viewer wears glasses equipped with polarizing plates having different polarization directions on the left and right sides.

For example, the polarization directions of the images for the left and right eyes may be orthogonal to each other, or in the case of circularly polarized light, the directions of rotation may be opposite to each other. Then, a stereoscopic image can be observed by inputting only images having polarization directions corresponding to the left and right eyes, respectively.

As a means for displaying or projecting stereoscopic images, in addition to methods using films and projectors, CRTs are also used.
Also, methods using an LCD (liquid crystal display) are known.

Among these methods, the method using CRT has various problems as follows.

First, by using a polarizing plate, the brightness of the image decreases by 50% or more.

Furthermore, if the left and right images are projected onto separate CRTs, the apparatus becomes large.

[0010] Therefore, the left and right images are time-divided into one CR.
It is also possible to project the image onto a T, but in order to suppress flicker and obtain the same quality as a normal CRT, in this case it is necessary to double the frame rate of the image signal. A new processing system must be designed/manufactured, resulting in high costs.

On the other hand, in the method using an LCD, by utilizing the polarizing plate originally included in the LCD, a separate polarizing plate is not required, and the brightness of the image does not decrease. Also, generally speaking, compared to CRT, LCD is
It is small, lightweight, simple and inexpensive, and even if separate LCDs are used for left and right images, there is no problem of the device becoming large or expensive.

0012

As described above, the method of using an LCD to project a stereoscopic image has various advantages over the CRT method, but there are specific problems caused by the structure of the LCD.

[0013] In Japanese Patent Application Laid-Open No. 63-74027, two LCDs with their polarization directions perpendicular to each other are arranged to face each other at an angle of 90°, and a
A structure is disclosed in which a half mirror is placed at an angle of 5 degrees and an observer wearing glasses whose polarization directions of left and right lenses are orthogonal is allowed to observe the image through the half mirror.

[0014] Here, it has been recognized that the advantage of using an LCD polarizing plate is that it eliminates the need for a polarizing plate, compared to, for example, a conventional system using a CRT and a polarizing filter.

However, the problem of displaying left and right images on LCDs with different polarization directions has not been recognized at all. In other words, the polarization direction of one of the two LCDs is
When the display image is rotated by 90 degrees with respect to the CD, the displayed image becomes an image in which the brightness and darkness are reversed, and even if it is observed together with the other image, a normal image cannot be observed.

[0016] To avoid this problem, the two LCDs must have different structures. For example, two L
The polarization directions of the polarizing plates constituting the CD polarizer and analyzer must be orthogonal to each other, and the orientation directions of the liquid crystals must also be orthogonal to each other. By configuring the LCD in this way, the manufacturing cost of the device increases.

Furthermore, as described above, in the method of observing (or projecting) the left and right parallax images with their polarization directions perpendicular, crosstalk between the left and right images occurs due to the tilt of the viewer's head. There is a problem of restricting posture.

An object of the present invention is to eliminate the above-described problems peculiar to LCDs, and to provide a small, lightweight, simple and inexpensive stereoscopic image display device that does not require modification or design changes to the LCD or its drive system. It is in.

[0019]

[Means for Solving the Problems] In order to solve the above problems, in the present invention, modulated by left and right parallax images,
In a stereoscopic image display device that displays a stereoscopic image by observing circularly polarized light images with different rotation directions on the left and right sides through an analyzer corresponding to these circularly polarized light directions with the left and right eyes of an observer, first and second liquid crystal displays whose linearly polarizing plates have the same polarization direction, respectively displaying parallax images; a quarter-wave plate disposed in front of the first and second liquid crystal displays; A configuration consisting of a semi-transmissive mirror that transmits circularly polarized light images transmitted through the quarter-wave plates in front of the first and second liquid crystal displays, and guides the circularly polarized light images toward the viewer or the projection screen by transmitting one and reflecting the other; Alternatively, first and second liquid crystal displays each displaying the left and right parallax images have the same polarization direction of the linear polarizing plates, and the linear polarization direction of the light image of either the first or second liquid crystal display is the same. A 1/2 wavelength plate rotated by 90 degrees, an optical image of the first or second liquid crystal display transmitted through this 1/2 wavelength plate, and 1/2
One of the light images from the second or first liquid crystal display that does not pass through the wave plate is transmitted, and the other is reflected to guide it toward the viewer or the projection screen, and convert the linear polarization directions of the two so that they are perpendicular to each other. A configuration consisting of a polarizing beam splitter and a quarter-wave plate that converts the emitted light of the polarizing beam splitter into circularly polarized light, or the liquid crystal display is configured with a first polarizing plate as a polarizer or an analyzer,
It consists of a liquid crystal driven to have a predetermined orientation by a transparent electrode, and a second polarizing plate serving as an analyzer or polarizer, and a linear polarization direction is formed on the first and/or second polarizing plate. By alternately forming first and second regions perpendicular to each other and driving the electrodes of the liquid crystal corresponding to these first and second regions, left and right parallax images are spatially divided and displayed, and the displayed image is circularly displayed. A configuration was adopted in which observation or projection was performed through a quarter-wave plate that converted into polarized light.

[0020]

[Operation] Among the above configurations, according to the first configuration using a semi-transmissive mirror, left and right parallax images of circularly polarized light in the same direction are formed by a quarter-wave plate, and these are each reflected by the semi-transmissive mirror. , by reversing the rotation direction of one of the circularly polarized lights by transmitting the light, it becomes possible to separate left and right parallax images of a stereoscopic image.

[0021] Also, a second beam splitter using a polarizing beam splitter
According to the configuration, the loss of light amount can be greatly improved compared to the case of a semi-transmissive mirror. In this case, the conversion into circularly polarized light takes place after exiting the polarizing beam splitter.

According to the third configuration, the left and right parallax images are spatially divided and displayed on a single liquid crystal display, their linear polarization directions are orthogonal to each other, and then they are converted into circularly polarized light with different directions. A single-panel stereoscopic image display device can be easily realized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on embodiments shown in the drawings.

<Embodiment using a half mirror> FIG. 1 shows the structure of a stereoscopic image display device employing the present invention. In FIG. 1, reference numerals 11 and 12 are LCDs for displaying images with parallax for the left and right eyes, respectively.
A wave plate 14 is arranged.

As the LCDs 11 and 12, those capable of monochrome or color dot matrix display, such as those used in liquid crystal TVs, are used, and these display surfaces (therefore, the 1/4 wavelength plates 13 and 14 as well) As shown in the figure, they face each other in orthogonal directions, and the LC
A half mirror 1 is installed in the area where the optical axes of D11 and D12 are perpendicular to each other.
5 is placed. The direction in which the half mirror 15 is arranged is at an angle of 45 degrees with the optical axes of the LCDs 11 and 12, respectively, as shown in the figure.

Only the arrangement of the LCD and the half mirror is exactly the same as that in the above-mentioned Japanese Patent Laid-Open No. 63-74027, but the structure of the LCDs 11 and 12 and the quarter-wave plates 13 and 14 are used. The difference is that

That is, in this embodiment, exactly the same LCDs 11 and 12 are used. Therefore, L
The linear polarization directions of the displayed light images of CDs 11 and 12 are exactly the same. Furthermore, the drive systems of the LCDs 11 and 12 may be exactly the same as those of conventional LCDs, and the image signals of the parallax images for the left and right eyes may simply be synchronously input as they are (
(The image on the reflected side must be flipped vertically or horizontally.) Further, as the LCDs 11 and 12, it is also possible to use a liquid crystal TV or the like as is.

[0028] In front of the LCDs 11 and 12, quarter-wave plates 13 and 14 are arranged, so that the LCD 11
, 12 parallax images, respectively, are circularly polarized.

Then, the image on one LCD 11 is transmitted through the half mirror 15, and the image on the other LCD 11 is transmitted as a transparent image.
If the image of D12 is observed as a reflected image, one of the circular polarization directions of these light images will be rotated to the left and the other will be rotated to the right.

On the other hand, the observer sees one quarter wavelength plate 17.
Behind the lens, viewing glasses 16 are worn, in which linear polarizing plates 18a and 18b for the left and right eyes, the linear polarization directions of which are orthogonal to each other, are placed one on top of the other.

The 1/4 wavelength plate 17 returns the circularly polarized light having different rotation directions of the left and right parallax images to linearly polarized light having orthogonal polarization directions, so that the images passing through the linearly polarizing plates 18a and 18b are for the left eye, respectively. and the right eye, respectively, and enter the observer's left and right eyes, respectively.

[0032] Note that a fluorescent lamp, an EL element, or other illumination can be arranged on the back side of the LCDs 11 and 12, if necessary. Also, if suitable lighting is possible, LC
D11 and D12 may be reflective elements.

[0033] Such a structure can be constructed using an LCD in an extremely small size, light weight, simple and inexpensive manner, and can be used for displaying a color or monochrome stereoscopic image in an ophthalmological examination device, a computer display, a video game device, etc.

According to the above configuration, the LCDs 11 and 1
Exactly the same thing can be used for 2, and it is exactly the same LC as before.
D elements and drive systems can be used for LCDs 11,12. Furthermore, since the polarization directions of the polarizing plates inside the LCDs 11 and 12 are the same, there is no need for means for correcting a reversed image.

As described above, in the method of observing an optical image of circularly polarized light through the viewing glasses 16 consisting of the 1/4 wavelength plate 17 and the linear polarizing plate 18, the observation is similar to the method using only the linear polarizing plate. Crosstalk between left and right images does not occur due to the tilt of the person's head.

Note that the displayed light image can be not only directly observed but also projected onto a screen, etc., but the embodiment described later is more advantageous in terms of the amount of display light.

<Example using beam splitter> FIG. 2
shows different embodiments. In FIG. 2, the arrangement and driving method of LCDs 11 and 12 are the same as in FIG.
, 12 structure, using a polarizing beam splitter (PBS) 23 instead of a half mirror, arrangement of polarizing means,
and the projection method is different.

In this embodiment, since the polychromatic polarizing beam splitter 23 is used, the LCDs 11 and 12 can be used without the front polarizing plate that functions as an analyzer.

The polarizing beam splitter 23 is arranged so that the transmission/reflection direction is the same as that of the half mirror 15 in FIG. Without placing a 4-wavelength plate, one
/4 wavelength plate 22 is arranged. On the other hand, a half-wave plate 21 is arranged between the LCD 12 and the polarizing beam splitter 23, which are observed using reflected light.

Note that the size of the LCDs 11 and 12 must be smaller than the size of the polarizing beam splitter 23. As such a small LCD, one used in a (color) viewfinder of a video camera, etc. can be used.

The light image emitted from the polarizing beam splitter 23 is projected onto the diffuser 25 at an arbitrary magnification via the lens 24, and the image on the diffuser 25 is as shown in FIG.
The image is observed by an observer wearing the same observation glasses 16 as .

In the configuration shown in FIG. 2, the light images emitted from the LCDs 11 and 12 have polarization components in two orthogonal directions because the polarizing plate on the front side is omitted.

Among these, if the polarization direction of the light having the information of the display light image is parallel to the plane of the drawing, then when the light image of the LCD 11 passes through the polarizing beam splitter 23, the polarization direction is parallel to the plane of the drawing. Only the display light image having .

On the other hand, if the polarization direction of the light transmitted through the polarization beam splitter 23 is as described above, the polarization direction of the light reflected from the polarization beam splitter 23 is only perpendicular to the plane of the paper.

Therefore, in this embodiment, in order to align the display light image having the same linear polarization direction (horizontal to the plane of the paper) as the LCD 11 with the polarization direction of the reflected light from the polarizing beam splitter 23, the half-wave plate 21 is placed in front of the LCD 12. It is located in

In this way, the left and right parallax light images having linear polarization directions perpendicular to each other are transmitted to the polarizing beam splitter 2.
3, are circularly polarized by a quarter-wave plate 22 so as to have different rotation directions, and are projected onto a diffuser 25 via a lens 24.

To observe the image, viewing glasses 16 exactly the same as those shown in FIG. 1 are used.

In the structure of FIG. 2, in addition to the effects obtained by the embodiment of FIG. 1, the polarizing beam splitter 23 has the advantage that there is no loss of light quantity unlike a half mirror, and high brightness display can be performed.

[0049] Furthermore, the polarizing beam splitter 23
Since the analyzers 11 and 12 are used in common, the structure is simple and has the advantage that it can be constructed easily and inexpensively.

Note that the image may be directly observed as in FIG. 1 without using the lens 24 and diffuser 25, but the lens 24 and diffuser 25 enable display on a large screen.

Further, the diffuser 25 (transmissive screen) in FIG. 2 is replaced by a reflective screen 26 as shown in FIG.
can be replaced with According to the reflective screen 26, a screen with a larger area can also be realized. The configuration other than the reflective screen 26 in FIG. 3 is completely the same as that in FIG. 2.

In the above, the polarizing plates (analyzers) on the front sides of the LCDs 11 and 12 are omitted, but there is no change in the operating principle or light intensity even if they are not removed, and the existing L
When using a CD, it may be possible to construct it at a lower cost if the CD is not removed.

<Embodiments using space-divided LCDs> In the above embodiments, two LCDs must be used, and a flat three-dimensional image display device, which is essential for laptops, notebook computers, etc. It is impossible to configure it.

[0054] Therefore, a method can be considered in which the left and right images forming a stereoscopic image are displayed on the same LCD, but the conventional time-division method requires processing of the video signal as described above, and requires an electronic circuit. There are complications.

Therefore, in this embodiment, the same LCD
Consider displaying the left and right images above by spatial division.

FIG. 4 shows the laminated structure of an LCD according to the present invention. From the rear of the figure, each of the illustrated layers includes a polarizing plate 31,
A transparent electrode 32, a color filter 33, a polarizing plate 34, and a quarter wavelength plate 35 are shown.

A liquid crystal 36 is laminated between the two transparent electrodes 32 for driving. The color filter 33 has three primary colors R, G, and B arranged in a stripe shape as shown in the figure.

As shown in the figure, the polarizing plate 34 has horizontal polarizing parts H and vertical polarizing parts V arranged alternately in a stripe pattern in a direction perpendicular to the direction in which the color filters 33 are arranged. Note that the polarization direction of the rear polarizing plate 31 is the same as that of either the horizontal polarizing section H or the vertical polarizing section V.

In the above configuration, the liquid crystals 36 at positions corresponding to the areas of the horizontal polarization section H and the vertical polarization section V whose polarization directions of the polarization plate 34 are perpendicular to each other are driven to spatially divide and display left and right parallax images. .

For this purpose, the electrodes of the transparent electrode 32 corresponding to the regions of the horizontal polarization section H and the vertical polarization section V may be connected as if they correspond to the two LCDs of FIGS. 1 to 3, or
This can be easily done by distributing left and right images using image control software using a microprocessor or the like.

A quarter-wave plate 35 is placed in front of the LCD configured and driven in this way, and a three-dimensional image is obtained by observing it through the same viewing glasses 16 as shown in FIG. be able to.

[0062] With this configuration, a single-panel stereoscopic image display device can be configured with a single LCD, so the device can be configured extremely compactly, and a flat single-panel stereoscopic image display device suitable for laptops, notebook computers, etc. An image display device can be configured. Further, the configuration of the drive circuit may be the same as that of a conventional LCD, and complicated hardware such as time division control is not required. Further, it is not necessary to vertically (or horizontally) invert one of the left and right parallax images as in the embodiments of FIGS. 1 to 3.

In the above configuration, the polarization direction of the rear polarizing plate 31 is the same as that of either the horizontal polarizing section H or the vertical polarizing section V. In this case, since the brightness of either the left or right parallax image displayed at the corresponding position of the horizontal polarization section H and the vertical polarization section V is reversed, the image signal of one of the left or right parallax images is converted into an inverted image. It is necessary to convert and input it.

To avoid this problem, the rear polarizing plate 3
Similarly to the polarizing plate 34, 1 also has a horizontal polarizing section H and a vertical polarizing section V.
It is preferable to adopt a structure in which a stripe structure is arranged alternately, and the pattern is inverted with respect to the polarizing plate 34. This eliminates the need for image signal brightness inversion processing.

[0065] Note that the LCD exemplified in the above embodiment
The arrangement direction of the mirror, half mirror, beam splitter, etc. is only an example, and can be changed as necessary. For example, in the configuration of FIG. 4, the stripe structure of the polarizing plate 34 is illustrated in the vertical direction, but if this direction is made to match the scanning line direction of the image signal, an image that combines the left and right parallax images can be created. Processing becomes easier.

Further, in the above description, the LCD is illuminated with transmitted light, but it goes without saying that the same principle can be applied to a reflective type.

[0067]

[Effects of the Invention] As is clear from the above, according to the present invention, an optical image of circularly polarized light modulated by left and right parallax images and having different rotation directions on the left and right sides can be detected by an analyzer corresponding to these directions of circularly polarized light. In a stereoscopic image display device that displays a stereoscopic image by allowing the viewer to observe it with the left and right eyes of an observer, first and second liquid crystal displays in which the polarization directions of linear polarizers are the same display the left and right parallax images, respectively. a quarter-wave plate placed in front of the first and second liquid crystal displays, and a circularly polarized light image transmitted through the quarter-wave plate in front of the first and second liquid crystal displays, A configuration consisting of a semi-transparent mirror that transmits one side and reflects the other to guide the viewer or the projection screen, or a first mirror with the same polarization direction of linear polarizers that display left and right parallax images, respectively.
and a second liquid crystal display, a half-wave plate that rotates the linear polarization direction of the light image of either the first or second liquid crystal display by 90 degrees, and a second liquid crystal display that is transmitted through the half-wave plate. The light image of the first or second liquid crystal display and the light image of the second or first liquid crystal display that does not pass through the 1/2 wavelength plate are transmitted to the viewer or the projection screen by transmitting one of them and reflecting the other. A configuration consisting of a polarizing beam splitter that guides the light in a direction and converts the linear polarization directions of the two so that they are orthogonal, and a quarter-wave plate that converts the output light of the polarization beam splitter into circularly polarized light, or the liquid crystal display. , a first polarizing plate serving as a polarizer or analyzer, a liquid crystal driven to have a predetermined orientation by a transparent electrode, and a second polarizing plate serving as an analyzer or polarizer; and/or by alternately forming first and second regions whose linear polarization directions are orthogonal to each other on a second polarizing plate, and driving liquid crystal electrodes corresponding to these first and second regions. The left and right parallax images are spatially divided and displayed, and the displayed image is observed or projected through a quarter-wave plate that converts it into circularly polarized light.The use of a liquid crystal display makes it compact, lightweight, and simple. It can be implemented at low cost, and in that case, there is no need to use a special structure for the liquid crystal display or its drive system.Furthermore, with a structure in which the left and right parallax images are spatially divided and displayed on one liquid crystal display, Furthermore, the device can be small, lightweight, simple and inexpensive to implement, and a flat, single-panel stereoscopic image display device suitable for laptops, notebook computers, etc. can be easily realized. It has excellent effects such as not requiring a special electronic circuit.

[Brief explanation of drawings]

FIG. 1: A first optical system of a stereoscopic image display device according to the present invention.
It is an explanatory diagram showing an example of.

FIG. 2: A second optical system of the stereoscopic image display device according to the present invention.
It is an explanatory diagram showing an example of.

FIG. 3: Third part of the optical system of the stereoscopic image display device according to the present invention.
It is an explanatory diagram showing an example of.

FIG. 4 Different LCDs of the stereoscopic image display device according to the present invention
It is an explanatory diagram showing an example of.

[Explanation of symbols]

11 LCD 12 LCD 13 1/4 wavelength plate 14 1/4 wavelength plate 15 Half mirror 16 Observation glasses 17 1/4 wavelength plate 18 Linear polarizing plate 21 Half wave plate 22 1/4 wavelength plate 23 Polarizing beam splitter 24 Lens 25 Diffuser 26 Reflective screen 31 Polarizing plate 32 Transparent electrode 33 Color filter 34 Polarizing plate 35 1/4 wavelength plate

Claims (4)

[Claims] [Claim 1] An optical image of circularly polarized light modulated by left and right parallax images and having different rotation directions on the left and right sides is observed by the left and right eyes of an observer through an analyzer corresponding to these circularly polarized light directions. In a stereoscopic image display device that displays a stereoscopic image, first and second liquid crystal displays whose linear polarizing plates have the same polarization direction display left and right parallax images, respectively, and the first and second liquid crystal displays A 1/4 wavelength plate placed in front and a 1/4 wavelength plate placed in front of the first and second liquid crystal displays.
The circularly polarized light image transmitted through the /4 wavelength plate is transmitted through one side,
A stereoscopic image display device characterized in that the other half comprises a semi-transmissive mirror that guides the viewer or the projection screen by reflecting it. 2. A circularly polarized light image modulated by left and right parallax images and having different rotation directions on the left and right sides is observed by the observer's left and right eyes through these circularly polarized light analyzers. A stereoscopic image display device for displaying images includes first and second liquid crystal displays whose linear polarizing plates have the same polarization direction and which display left and right parallax images, respectively;
or a 1/2 wavelength plate that rotates the linear polarization direction of any of the optical images of the second liquid crystal display by 90 degrees, and an optical image of the first or second liquid crystal display that is transmitted through this 1/2 wavelength plate. and 1
/ A light image from the second or first liquid crystal display that does not pass through the two-wavelength plate is transmitted through one side, and the other is reflected so that it is guided toward the viewer or the projection screen, and the linear polarization directions of both are perpendicular to each other. A stereoscopic image display device comprising: a polarizing beam splitter for converting polarized light; and a quarter-wave plate for converting light emitted from the polarized beam splitter into circularly polarized light. 3. An optical image of circularly polarized light modulated by left and right parallax images and having different rotation directions on the left and right sides is observed by the left and right eyes of an observer through an analyzer corresponding to these circularly polarized directions. In a stereoscopic image display device that displays a stereoscopic image, the liquid crystal display comprises a first polarizing plate as a polarizer or an analyzer, a liquid crystal driven to have a predetermined orientation by a transparent electrode, and an analyzer. or a second polarizing plate as a polarizer, and on the first and/or second polarizing plate there is a first polarizing plate whose linear polarization directions are orthogonal to each other.
and a second region are alternately formed, and by driving the electrodes of the liquid crystal corresponding to the first and second regions, left and right parallax images are spatially divided and displayed, and the displayed image is converted into circularly polarized light. A stereoscopic image display device characterized by observing or projecting through a /4 wavelength plate. 4. The liquid crystal display device has a color filter in which primary color areas are arranged in a predetermined pattern, and displays a color stereoscopic image by driving the electrodes of the corresponding primary color areas. A stereoscopic image display device according to.