JPH02181138A - Liquid crystal projection type stereoscopic display device - Google Patents

Abstract

PURPOSE:To prevent the loss of the quantity of light by the mismatching of polarization directions by disposing polarized light rotating elements consisting of two sheets of quarter-wave plates respectively to the light incident and exit surfaces of the liquid crystal display element. CONSTITUTION:This device has a 1st polarized beam splitter 2 which separates the luminous flux from a light source 1 to the two luminous fluxes of the linearly polarized light intersecting orthogonally with each other in the polarization direction, the 1st liquid crystal display element 5 which modulates either of the two luminous fluxes in accordance with the image signal for the right eye and the 2nd liquid crystal display element 6 which modulates the other of the luminous fluxes in accordance with the image signal for the left eye. The device has a 2nd polarized beam splitter 11 which synthesizes the two luminous fluxes modulated by the two liquid crystal display elements 5, 6 again to one luminous flux. The images of the 1st and 2nd liquid crystal display elements 5 and 6 are projected onto a screen 16 and the images are observed through polarizing spectacles 17. The polarized light rotating elements 7 to 10 consisting of two sheets of the quarter-wave plates are respectively disposed to the light incident and exit surfaces of the 1st and 2nd liquid crystal display elements 5 and 6. The loss of the quantity of light by the mismatching of polarizing directions is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stereoscopic display device that provides a display image with a three-dimensional effect, and particularly to a liquid crystal projection type stereoscopic display device that projects a liquid crystal display element.

[Conventional technology]

In recent years, large-screen stereoscopic display devices have been desired in order to create a powerful and realistic screen experience. To achieve this, 1
Many stereoscopic display devices have been proposed in the past, in which a stereoscopic image is generated using a projector, a CRT projector, or the like, and is observed using polarized glasses.

Among them, a liquid crystal projection type stereoscopic display device using a liquid crystal display element is described in the specification of Japanese Patent Application No. 174898/1988 1 "Projection Type Stereoscopic Television Receiver".

FIG. 3 is a plan view of a liquid crystal projection type stereoscopic display device for explaining such a conventional example.

According to this conventional example, the liquid crystal projection type stereoscopic display device has a third
As shown in the figure, a light TA 50, a first polarizing beam splitter 51, mirrors 52, 53, a left eye image liquid crystal device 54, a right eye image liquid crystal device 55, and a second polarizing beam splitter 56 and a projection lens 57,
An image is projected onto the screen 61 in the following manner.

That is, from the light source 50 to the first polarizing beam splitter 5
1, the projected light 58 is split by the first polarizing beam splitter 51 into first polarized light 59 and second polarized light 60, whose polarization planes are orthogonal to each other. The first polarized light 59 has its optical path changed by the mirror 52 and then enters the left eye image liquid crystal device 54 . The left eye image liquid crystal device 54 modulates the first polarized light 59 based on the left eye video signal. The modulated first polarized light 59 is projected onto the screen 61 via the second polarized beam splitter 56 and the projection lens 57.

Further, after the optical path of the second polarized light 60 is changed by the mirror 53, it enters the right eye image liquid crystal device 55.

The right-eye image liquid crystal device 55 modulates the second polarized light 60 based on the right-eye video signal. The modulated second polarized light 60 is transmitted to a second polarized beam splitter 56 and a projection lens 57.
is projected onto the screen 61 via.

In this way, an image by the left-eye image liquid crystal device 54 and an image by the right-eye image liquid crystal device 55 are projected onto the screen 61, and the viewer can wear polarized glasses 6.
By observing the image on the screen 61 through 2, it is possible to observe a three-dimensional image with a sense of nesting.

[Problem to be solved by the invention]

However, such a conventional configuration has the following problems when put into practical use.

In other words, -i, in direct-view type liquid crystal display elements used in liquid crystal televisions, in order to widen the viewer's viewing angle,
The alignment direction of the liquid crystal, as well as the polarization direction of the light transmitted through the polarizer and the polarizing plate serving as the analyzer, are inclined at 45 degrees with respect to the vertical direction of the displayed image.

On the other hand, in the configuration of the conventional example, the polarization direction of the light transmitted through the first polarization beam splitter 5 and the second polarization beam splitter 56 in FIG. 3 is parallel or perpendicular to the vertical direction of the displayed image. It is. Therefore, in the conventional configuration, the left eye image liquid crystal device 54. When the liquid crystal television is used as the right-eye image liquid crystal device 55, that is, when the displayed image is tilted at 45 degrees with respect to the vertical direction as described above, due to the mismatch in the polarization direction, the amount of transmitted light is smaller than that transmitted through the liquid crystal television. When the light is transmitted through the second polarizing beam splitter, the amount of light decreases by about 1/2, and as a result, about 75% of the light is lost, resulting in a problem that the brightness of the display screen becomes significantly darker. there were.

In addition, in order to match the polarization direction, changing the alignment direction of the liquid crystal and the polarization direction of the light that passes through the polarizing plate requires special modifications to the LCD TV manufacturing equipment and the use of new manufacturing methods. However, the versatility of LCD televisions cannot be obtained.

An object of the present invention is to provide a liquid crystal projection type stereoscopic display device that has a simple configuration, does not require changes to the manufacturing method of the liquid crystal television, and can provide a bright display screen that does not cause loss of light amount due to mismatching of polarization directions. There is a particular thing.

[Means to solve the problem]

The present invention includes a first polarizing beam splitter that separates a light beam from a light source into two linearly polarized light beams whose polarization directions are orthogonal to each other; a first liquid crystal display element that modulates the other of the two luminous fluxes based on a left eye image signal; and two liquid crystal display elements modulated by the first and second liquid crystal display elements, respectively. and a second polarizing beam splitter that combines the luminous flux into one luminous flux again, projects the image of the first liquid crystal display element and the image of the second liquid crystal display element onto a screen, and projects the image of the first liquid crystal display element and the image of the second liquid crystal display element onto the screen through polarized glasses. A liquid crystal projection type stereoscopic display device for observing the above image, wherein polarized light consisting of two 174-wavelength plates is provided on the light incident and exit surfaces of the first liquid crystal display element and the second liquid crystal display element. It is characterized by the arrangement of rotating elements.

[Effect]

When polarization rotation elements consisting of two 174-wavelength plates are placed on the light incident and exit surfaces of the liquid crystal display element, the light incident from the polarizing beam splitter for separation and the polarized beam for recombination with the liquid crystal display element are separated. The polarization direction can be matched with the splitter, and even if the liquid crystal display element used in general LCD TVs is used, loss of light amount due to mismatching of the polarization direction can be prevented. . Therefore, it is possible to provide a liquid crystal projection type three-dimensional display device that has a simple configuration and can provide a bright display screen that does not cause loss of light M due to mismatching of polarization directions.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a plan view of a liquid crystal projection type stereoscopic display device for explaining one embodiment of the present invention.

As shown in FIG. 1, the device of this embodiment includes a light source 1 and a first
a polarized beam subric 2 and a second polarized beam subric 11, mirrors 3 and 4, and two liquid crystal display elements 5,
6 and a projection lens 12 for projecting the images of the liquid crystal display elements 5 and 6 onto the screen 16.
The image on the liquid crystal display element 6 is observed using polarized glasses 17, and a polarization rotation element is provided on the input/output side of each liquid crystal display element 5, 6.

That is, on the liquid crystal display element 5 side, first and second polarization rotation elements 7 for the liquid crystal display element 5 are provided on the incident plane and the output plane.
. There is.

The first polarizing beam splitter 2 is a polarizing beam splitter for separating a light beam from a light source into two linearly polarized light beams whose polarization directions are orthogonal to each other. The projection light 14 is P-polarized light and the projection light 15 is S-polarized light, which have planes of polarization perpendicular to each other.

Each liquid crystal display element 5.6 can be a liquid crystal display element used in a liquid crystal TV set on a boat.

One of these is for the right eye and the other is for the left eye, and the video signals of the right eye image and the left eye image having binocular parallax information are respectively input. In this embodiment, the liquid crystal display element 5 is for the right eye image, the liquid crystal display element 6 is for the left eye image, and the liquid crystal display element 5 is for the first polarizing beam splitter. 2
Projection light 1 separated by and reflected by mirror 3
4 constitutes a first liquid crystal display element that modulates the image signal for the right eye based on the image signal for the right eye, and the liquid crystal display element 6 uses the other light beam separated by the first polarizing beam splitter 2 and reflected by the mirror 4. It constitutes a second liquid crystal display element that modulates a certain projection light 15 based on a left eye image signal.

The second polarizing beam splitter 11 includes a liquid crystal display element 5,
This is a polarizing beam splitter used to combine the two light beams modulated by 6 into one light beam again.

a polarization rotation element 7 disposed on the incident surface and the exit surface of the liquid crystal display element 5 to which the reflected projection light 14 from the mirror 3 is applied;
8, and furthermore, polarization rotation elements 9 and 10 arranged on the incident surface and the exit surface of the liquid crystal display element 6 to which the reflected projection light 15 from the mirror 4 is applied, rotate the projected light 14, the projected light 15, and the liquid crystal display element 5. ．． It is used to match the polarization direction between the liquid crystal display element 6 and the second polarizing vinyl printer 11, and each is composed of two 174-wavelength plates.

A liquid crystal display element 5, each having polarization rotation elements 7 to 10 each comprising two quarter-wave plates as described above on the entrance/exit surface side;
6, the second polarizing beam splitter 11, the projection lens 12, and the screen 16 are positioned such that each pixel of the liquid crystal display element 5 and the liquid crystal display element 6 is imaged at the same location on the screen 16. placed in relationship.

As described above, the device of this embodiment includes a light source 1, a first polarizing beam splitter 2 that separates the light beam from the light source 1 into two light beams that are linearly polarized lights whose polarization directions are orthogonal to each other, and a first liquid crystal display element that modulates one of the two based on the image signal for the right eye, and a second liquid crystal display element that modulates the other based on the image signal for the left eye; A second polarizing beam splitter 11 combines the images into a single beam of light again, and a screen 16 displays the image of the first liquid crystal display element and the image of the second liquid crystal display element.
In a liquid crystal projection type three-dimensional display device that is configured at least of a projection lens 12 for projecting an image upward and for observing an image on a screen 16 through polarized glasses 17, the first liquid crystal display element and the second liquid crystal display element A polarization rotation element 7 consisting of two 174-wavelength plates is placed on the light entrance and exit surfaces of
~10 are arranged respectively.

In the liquid crystal projection type stereoscopic display device having the configuration shown in FIG. 1, the projection of the images of each of the liquid crystal display elements 5 and 6 onto the screen 16 and the observation of the stereoscopic display screen with a sense of depth are performed as follows. Moreover, in this case, even if the liquid crystal display elements 5 and 6 are liquid crystal display elements used in general liquid crystal TVs,
There is no loss of light amount as in the case of the configuration shown in Figure 3,
The brightness of the display screen may become significantly darker.

This will be explained in detail below.

In FIG. 1, a light source 1 generates projection light 13. In FIG.

The projected light 13 enters the first polarizing beam splitter 2,
Projected light 14. which is linearly polarized light having mutually orthogonal polarization planes of P-polarized light and S-polarized light, respectively. The projected light 15 is separated into two beams. The projected light 14 changes its optical path by the mirror 3 and enters the first polarization rotation element 7 on the incident surface example for the liquid crystal display element 5, the liquid crystal display element 5, and the second polarization rotation element 8 on the exit surface side. .

On the other hand, the projected light 15 changes its optical path by the mirror 4,
a first polarization rotation element 9 on the incident surface side for the liquid crystal display element 6;
The light enters the liquid crystal display element 6 and the second polarization rotation element 10 on the exit surface side.

The projected light 14.1.5 is modulated and made incident on the second polarization heam splint 11 for recombination. In this case, each polarization rotation element 7 to 10 each consists of two quarter-wave plates. Since such polarization rotation elements are arranged on the light incident and exit surfaces of the liquid crystal display element, the amount of transmitted light does not decrease as in the conventional case.

This can be explained as follows.

That is, No. 2M is a diagram used to explain the principle of the present invention. To explain using this FIG. 2, first, the wave plate is:
It uses the phase difference that occurs when light travels through a medium with refractive index anisotropy to change the polarization state of light. In particular, the 174 wavelength plate has the function of converting linearly polarized light of incident light into circularly polarized light, or circularly polarized light into linearly polarized light.
When a polarization rotation element is constructed using two 74-wavelength plates, it is possible to arbitrarily rotate the polarization direction of linearly polarized light.

The present invention utilizes the above principle.

First, in FIG. 2(a), it is assumed that the projected light 28 is P-polarized linearly polarized light that has passed through a polarizing beam splitter for separation. In this case, the polarization direction 29 of the projected light 28 is
It is perpendicular to the vertical direction 27 of the display screen of the liquid crystal display element 26. On the other hand, the polarization direction that can be transmitted through the liquid crystal display element 26 is the polarization direction 32 inclined at 45 degrees with respect to the vertical direction 27 of the display screen in the case of a -g liquid crystal television as described above.

Therefore, if the projected light 28 directly enters the liquid crystal display element 26, the projected light 28
The amount of light will be reduced by about half. Therefore, in the case of P-polarized linearly polarized light, as shown in FIG. When the first polarization rotation element 22 on the incident surface side consisting of The direction 29 is converted into circularly polarized light 30 by the first quarter-wave plate 20, and then converted into linearly polarized light in the polarization direction 31 by the second 174-wave plate 21. In order for this polarization direction 31 to be the same as the polarization direction 32 that can be transmitted through the liquid crystal display element 26, the second 1/2
The refractive index anisotropic axis of the four-wavelength plate 21 is the vertical direction 27 of the display screen.
This is possible by setting it perpendicular or parallel to. Therefore, since the polarization direction can be matched, no loss in the amount of the projected light 28 occurs. Next, the light that has passed through the liquid crystal display element 26 needs to enter the polarized beam brick for resynthesis again, or if it enters directly here as well, the light intensity of the projected light 28 will decrease due to the mismatch in the polarization direction described above. Lose. Therefore,
Similarly, when the second polarization rotation element 25 on the exit surface side consisting of the third 174 wavelength plate 23 and the fourth /4 wavelength plate 24 is arranged on the exit surface of the liquid crystal display element 26, the projected light 28 becomes The third 174-wave plate 23 can sequentially convert the light into circularly polarized light 33, and the fourth 174-wave plate 24 can sequentially convert the light into linearly polarized light in the polarization direction 34. Since the polarization directions can be matched, no loss of light quantity occurs.

That is, the amount of transmitted light can be increased even when transmitted through the polarizing beam splitter during recombination.

FIG. 2(b) shows a case where the projected light 36 is S-polarized linearly polarized light that has passed through a polarizing beam splitter.

In this case, S-polarized linearly polarized light, that is, Fig. 2 (a
) is a linearly polarized light whose polarization direction is orthogonal to the P-polarized linearly polarized light. Therefore, the polarization direction 37 of the projected light 36 is parallel to the vertical direction 27 of the display screen of the liquid crystal display element 26.

When such projected light 36 is separated from the polarizing beam splitter for separation in the previous stage and is incident, the projected light 36 is converted into circularly polarized light 38 by the first 174-wave plate 20 and circularly polarized light 38 by the second 174-wave plate 21. It is converted into linearly polarized light with a polarization direction 39. This polarization direction 39 is the same as the polarization direction 40 that can be transmitted through the liquid crystal display element 26. Therefore, the polarization direction can be matched by the first polarization rotation element 22 on the incident surface side.

Next, as in the case of FIG. 2(a), matching can be performed for the subsequent recombining polarizing beam splitter. That is, the third 1/4 wavelength plate 23 converts the light into circularly polarized light 41, the fourth 174 wavelength plate 24 converts it into linearly polarized light with a polarization direction 42, and the second polarization rotation element 25 on the exit surface side converts the polarized light into circularly polarized light 41. can be harmonized.

In this way, by arranging polarization rotation elements consisting of two 1/4 wavelength plates on the light entrance and exit surfaces of the liquid crystal display element, light loss due to mismatching of the polarization direction can be prevented with a simple configuration. Therefore, it is possible to realize a liquid crystal projection type stereoscopic display device that can provide a bright display screen with no brightness.

Now, returning to FIG. 1, there is a polarization rotation element on the exit surface side for each of the liquid crystal display element 5 and the liquid crystal display element 6, that is, the first polarization rotation element 7. Second polarization rotation element 8. The first polarization rotation element 9 and the second polarization rotation element 10, the projected light 14.
Projection light 15, liquid crystal display element 5, e, high display element 6 and second
The polarizing beam splitter 11 is used to match the polarization direction with the polarizing beam splitter 11, and each consists of two 174-wavelength plates.

In this embodiment, the first polarization rotation element 7 and the second polarization rotation element 8 on the exit surface side for the liquid crystal display element 5 are the first polarization rotation element 22 and the second polarization rotation element 8 in FIG. 2(a), respectively. It has the same configuration as the polarization rotation element 25 of No. 2, and each has two 174-wave plates 20, 21, and 1/4-wave plates 2324.
The first polarization rotation element 9 and the second polarization rotation element 10 on the exit surface side for the liquid crystal display element 6 are respectively the first polarization rotation element 22 in FIG. 2(b). and the second polarization rotation element 25, and these also have the same configuration as the 174 wavelength plates 20, 21, and 17 in FIG. 2(b).
It consists of two 174-wavelength plates, 4-wavelength plates 23 and 24, and the projected light 14.24 shown in FIG. The projected light 15 reaches the projection lens 12 without reducing the amount of light unlike the conventional one, and at this time, it is modulated by the right eye image signal and the left eye image signal, respectively, and is transmitted to the screen 16. projected upwards.

That is, as described above, the positional relationship between the liquid crystal display element 5, the liquid crystal display element 6, the second polarizing beam splitter 11, the projection lens 12, and the screen 16 is such that each pixel of the liquid crystal display element 5 and the liquid crystal display element 6 is They are arranged so that the images are formed at the same location on each screen 16'',
Both the projection light 14 and the projection light 15 are projected onto the screen 16 via the second polarizing beam splitter 11 and the projection lens 12.

In order to observe a stereoscopic display screen with a sense of depth from the images on the screen 16 on which the images of the liquid crystal display element 5 and the image of the liquid crystal display element 6 are projected in this way, the following procedure may be performed.

That is, using the liquid crystal projection type stereoscopic display device shown in FIG.
In order to obtain a stereoscopic display screen with a sense of depth, first, video signals of a right-eye image and a left-eye image having binocular parallax information are input to the liquid crystal display element 5 and the liquid crystal display element 6, and are displayed. Make it. Here, as described above, the liquid crystal display element 5 displays an image for the right eye, and the liquid crystal display element 6 displays an image for the left eye.
If displayed in this way, each image is projected onto the screen 16, and in this case, the projected light 14 of the liquid crystal display element 5 is linearly polarized light of P polarization, and the liquid crystal display The projected light 15 of the element 6 is S-polarized linearly polarized light and is projected onto the screen 16, respectively.

In this state, the viewer observes the image on the screen 16 through the polarized glasses 17. Here, polarized glasses 1
7 is composed of two polarizing plates, which are arranged in front of the right eye and the left eye, respectively. However, if the polarizing plate is placed in front of the right eye, the polarizing direction of the light passing through the polarizing plate is the same as the polarizing direction of the projected light 14 projecting onto the liquid crystal display element 5 on which the image for the right eye is displayed. For the polarizing plate placed in front of the left eye, the projection light 1 that projects the liquid crystal display element 6 on which the image for the left eye is displayed is the same as that for the left eye.
It is necessary to arrange each polarizing plate so that the direction of polarization is the same as that of No. 5. Furthermore, since the projected light 14 and the projected light 15 are P-polarized light and S-polarized light, respectively, and have polarization directions perpendicular to each other, the two polarizing plates of the polarized glasses 17 are also They will be placed orthogonally.

When observing the image on the screen 16'' using such polarized glasses 17, the observer will see only the right-eye image with the right eye and the left-eye image with the left eye, and each image will be Since each image has binocular parallax information, it is possible to observe a 3D display screen with a sense of depth, and as mentioned above, it is also possible to ensure a sufficient amount of light, so when observing 3D images, it is possible to observe a 3D display screen with a bright display screen. can do.

Note that the liquid crystal display element 5 displays the left eye image, and the liquid crystal display element 6 displays the image for the left eye.
When displaying an image for the right eye, it is preferable to arrange the polarizing glasses 17 so that the polarizing plates of the polarizing glasses 17 have opposite polarization directions.

The following is a description of the light source 1, polarization heel splints 2 and 11, mirrors 3 and 4, and polarization rotation elements 7 to 1 used in the liquid crystal projection type stereoscopic display device having the configuration shown in FIG.
This is a specific example of a 1/4 wavelength plate at 0, each liquid crystal display element 5, 6, screen 16, etc.

As for the light source 1, a high brightness white light source such as a halogen lamp or a xenon lamp was used. Further, although not clearly shown in the drawings, in order to prevent other components from being deteriorated by the projection light 13, the projection light 13 is passed through a filter that transmits only visible light.

Both the first polarizing beam splitter 2 and the second polarizing beam splitter 11 are constructed by coating one slope of two right-angled prisms with a semi-transparent film made of a metal film, dielectric multilayer film, etc., and joining the slopes to each other. In particular, a light beam with wavelengths in the visible range that can be effectively separated into P-polarized light and S-polarized light, which are mutually orthogonal polarization components, was used, and its extinction ratio was approximately 20 dB. Furthermore, an antireflection film was applied to the light exit surfaces of the first polarizing beam splitter 2 and the second polarizing beam splitter 11.

The mirrors 3 and 4 are both surface mirrors made of aluminum, but reflectance-enhancing mirrors with particularly high reflectance using a dielectric multilayer film or the like are used.

Further, as the 174-wavelength plates in each of the polarization rotation elements 7 to 10, each consisting of two 174-wavelength plates, a polyvinyl alcohol film stretched to have birefringence was used.

Furthermore, as mentioned above, the liquid crystal display elements 5 and 6 used are those used in boat fishing, and specifically, the liquid crystal display elements 5 and 6 are TN (twisted nematic). ) type liquid crystal cell, and we used an active matrix type in which thin film transistors are arranged in a matrix for each pixel to drive the liquid crystal, but there are also simple matrix type or active matrix type in which thin film diodes are arranged. Liquid crystal display elements used in general liquid crystal TVs, such as a liquid crystal display device, can be used. However, screen 16
When viewed from the side, the liquid crystal display element 5 and the liquid crystal display element 6 are
Since they are mirror images of the bonding surface of the second polarizing beam brick 11, it is necessary to reverse the image formation of one liquid crystal display element horizontally. This may be realized by a signal system, or by arranging one of the liquid crystal display elements upside down.

As for the screen 16, a screen having polarization maintaining properties, such as a rear screen made of an acrylic plate or a reflective screen having a metal anti-fouling surface, was used.

In the configuration shown in FIG. 1, the liquid crystal display element 5 and the liquid crystal display element 6 can be used for either monochrome display or color display with a built-in color filter. Also,
Even when the projected light is separated into three colors (red, blue, and green) by a dichroic filter, each enters three liquid crystal display elements, and then combined again by a dichroic ink filter for color display, the liquid crystal display A similar liquid crystal projection type three-dimensional display device can be obtained by arranging polarization rotation elements on each of the light input and output surfaces of the element.

〔Effect of the invention〕

As explained above, according to the present invention, by arranging the polarization rotation element consisting of two 174-wavelength plates on the light incident surface and the light exit surface of the liquid crystal display element, the projected light and the liquid crystal display element , and the polarization direction of the light entering the polarizing beam splitter is matched, so there is no loss of light quantity,
A brighter three-dimensional display image can be obtained with a simpler configuration than in the conventional example.

[Brief explanation of the drawing]

1 is a plan view of a liquid crystal projection type stereoscopic display device for explaining an embodiment of the present invention; FIG. 2 is a perspective view of a polarization rotation element and a liquid crystal display element for explaining the principle of the present invention; FIG. FIG. 3 is a plan view of a liquid crystal projection type stereoscopic display device for explaining a conventional example. 1...Light source 2...First polarizing beam splitter 3.4...
...Mirror 5.6.26...Liquid crystal display element 7.9.22...First polarization rotation element 8, 1.0.25...Second polarization rotation element 11...
...Second polarizing beam splitter]2...Projection lens 13, 14.1.5.28.36...Projection light 16...
... Screen 17 ... Polarized glasses

Claims (1)

[Claims] (1) A first polarizing beam splitter that separates a light beam from a light source into two linearly polarized light beams whose polarization directions are orthogonal to each other, and modulates one of the two light beams based on a right eye image signal. a first liquid crystal display element that modulates the other of the two luminous fluxes based on a left eye image signal;
a second liquid crystal display element that combines the two light beams modulated by the first and second liquid crystal display elements into one light beam again.
a polarizing beam splitter, which projects an image of a first liquid crystal display element and an image of a second liquid crystal display element onto a screen, and observes the image on the screen through polarized glasses. In the display device, polarization rotation elements each consisting of two quarter-wave plates are arranged on the light incident and exit surfaces of the first liquid crystal display element and the second liquid crystal display element, respectively. Characteristic liquid crystal projection type 3D display device.