JPH0363619A - Projection stereoscopic video reproducing device, phase plate used for the same and its manufacture, and stereoscopic video reproduction system - Google Patents

Abstract

PURPOSE:To reproduce a stereoscopic video which has high contrast without being affected by external light by irradiating a transmission type screen from behind with two kinds of projection light which differ in polarized state and displaying videos for the left and right eyes. CONSTITUTION:A left-eye signal L and a right-eye signal R which are outputted from a signal source 1 are supplied to input terminals 2 and 2' and the left-eye signal L is amplified by a signal circuit 4 to drive respective projection tubes 5R, 5G, and 5B for red, green, and blue. Then left-eye projection light 11 is projected on the back side of the transmission type screen 13 by projection lenses 6R, 6G, and 6B through a polarizing filter 8 to form a left-tye video and the right-eye signal R is processed similarly. When this video is viewed through polarizing spectacles 16 having a specific polarization angle and then a stereoscopic image which provides a feeling of depth can be reproduced by the both-eye parallax like a reflection type screen without being affected by external light.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention projects two types of projection light with different polarization states onto a screen to display a left-eye image and a right-eye image on the screen, respectively. In particular, the present invention relates to a projection type stereoscopic video playback device that plays back stereoscopic video with a sense of depth.

The present invention also relates to a phase plate used in the projection type three-dimensional image reproduction apparatus, and a method for manufacturing the phase plate.

The present invention also relates to a stereoscopic video reproduction system.

[Conventional technology]

Conventionally, a device for reproducing a stereoscopic image with a sense of depth from a left-eye video signal and a right-eye video signal was developed in 1983.
As described in Publication No. 56889, left-eye images and right-eye images with different polarization states are projected onto a reflective screen, and the projected light reflected by the screen is viewed using polarized glasses. It had become.

Furthermore, as described in Japanese Patent Application Laid-open No. 62-285595, a time-sharing shutter is used to alternately reproduce the left-eye image and the right-eye image on the display in chronological order, and the left-eye image is incident only on the left eye. However, stereoscopic images were reproduced using polarized glasses so that the images for the right eye entered only the right eye.

[Problem to be solved by the invention]

Among the conventional technologies mentioned above, devices that play back 3D images by projecting left-eye and right-eye images on a reflective screen are susceptible to external light and play back 3D images with a high contrast ratio. The problem was that I couldn't do it. Also, when playing non-stereoscopic images,
There was also the problem that the brightness of the screen was not sufficient.

The present invention has been made in view of the problems of the prior art described above, and therefore, an object of the present invention is to provide a projection type 3D image that can reproduce high-contrast 3D images without being affected by external light. The purpose is to provide a video playback device.

Another object of the present invention is to provide a projection type three-dimensional image reproducing apparatus that can obtain sufficient screen brightness even when reproducing non-stereoscopic images.

[Means to solve the problem]

In order to achieve the former of the above objects, the present invention uses a transmissive screen, projects left-eye projection light and right-eye projection light from the back of the transmissive screen,
By displaying images for the left eye and images for the right eye,
I started playing stereoscopic images.

In addition, in order to achieve the latter objective, in the present invention, when reproducing a non-stereoscopic image, the same video signal is sent to the left eye signal circuit and the right eye signal circuit instead of the left eye video signal and the right eye video signal. At the same time, the left-eye polarizing filter is removed from the front surface of the left-eye projection optical system, and the right-eye polarizing filter is removed from the front surface of the right-eye projection optical system.

[Effect]

In the present invention, by using a transmissive screen and projecting a left-eye projection light and a right-eye projection light from the back of the transmissive screen to display a left-eye image and a right-eye image, respectively, the influence of external light It is possible to play high-contrast 3D images without any interference.

However, when a plastic screen is used as the transmissive screen, when linearly polarized light is incident on the transmissive screen, the orthogonally polarized light will be orthogonally polarized due to birefringence caused by residual mechanical stress strain during screen molding. The light is divided into two polarized components. Since the velocities within the transmission screen are different from each other, the phase of one polarized light component lags behind the phase of the other polarized light component when emitted, creating a relative phase difference (retardance) between the two. and the combination of the two becomes elliptically polarized light. Therefore, when viewing the projected light for the left eye and the projected light for the right eye that have passed through the transmission screen using polarized glasses, a portion of the projected light for the left eye is transmitted to the right eye, and a portion of the projected light for the right eye is transmitted to the left eye. As a result, the left-eye image and the right-eye image are not sufficiently separated, making it impossible to reproduce stereoscopic images based on binocular parallax, resulting in a ghost image that appears double.

However, in the present invention, this problem is solved by optimizing the molding method, molding conditions, or post-molding treatment to obtain a plastic screen with low birefringence and using the screen as the transmission screen. be able to.

Furthermore, even when a screen with birefringence is used as a transmission screen made of plastic, in the present invention,
This problem is solved by arranging a phase plate made of a transparent plastic film in the optical path of the left-eye projection light and right-eye projection light from the left-eye polarizing filter and the right-eye polarizing filter to the transmission screen. be able to.

That is, the phase plate has a polarity whose absolute value is almost the same as that of the transmissive screen made of plastic, but with an opposite sign. Therefore, when linearly polarized light is incident on the phase plate, its birefringence However, when the elliptically polarized light enters the transmission screen, it becomes linearly polarized light again due to its birefringence, and is emitted as elliptically polarized light by the phase plate. The birefringence of the mold screen can be compensated for.

Further, in the present invention, when reproducing a non-stereoscopic image, the left eye signal circuit and the right eye signal circuit transmit the same video signal instead of the left eye video signal and the right eye video signal, respectively. The projected light from the right-eye projection optical system and the right-eye projection optical system have the same image content, so the brightness on the screen is equal to the brightness of the right-eye projection light from the left-eye projection optical system. This is the sum of the brightness of the projected light from the optical system.

Further, removing a left-eye polarizing filter having a transmittance of about several tens of percent from the front surface of the left-eye projection optical system, and removing a right-eye polarizing filter having a transmittance of about several tens of percent from the front surface of the right-eye projection optical system, respectively. Accordingly, the screen brightness can be increased several times or more.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of a projection type stereoscopic video playback device as an embodiment of the present invention, in which (a) shows the state when playing back a stereoscopic video, and (b) shows a state when playing back a non-stereoscopic video. The state of each is shown.

2(a) is a plan view showing the projector section in FIG. 1, and FIG. 2(b) is a front view of the projector section.

First, in this embodiment, the operation when reproducing a stereoscopic image will be explained using FIG. 1(a).

In FIG. 1(a), the signal source 1, for example, generates a left eye video signal (hereinafter referred to as the left eye signal) L and a right eye video signal (hereinafter referred to as the right eye signal) R as different bit strings. This is a stereoscopic video disc player that reproduces a left eye signal R and a right eye signal R from an optical disc recorded in parallel and spirally.

The left eye signal R and the right eye signal R output from the signal source 1 are each supplied to an input terminal 2.2°.

The left eye signal supplied to the input terminal 2 is amplified to a predetermined signal level by the signal circuit 4, and is used for red (R) color.

Projection tubes (cathode ray tubes) for green (G) hue and blue (B) color
Drives 5R, 5G, and 5B. Projection tube 5R.

The left-eye projection light 11 emitted from the phosphor screens 5G and 5B is projected onto the transmissive screen 13 by projection lenses 6R, 6G, and 6B, respectively, to form an enlarged television image on the transmissive screen 13.

On the other hand, the right eye video signal R supplied to the terminal 2' is input to the signal circuit 4' via the contacts 3A and 3C of the switch 3, and is amplified to a predetermined signal level. Each projection tube 5R' for blue color.

5G", 58" is driven. Projection tube 5R", 5G.

Right eye projection light 11'' emitted from 5B' is projected onto the transmissive screen 13 by projection lenses 6R', 6G'' and 6B', respectively, to form an enlarged television image on the transmissive screen 13.

Note that the mirror 12 is a plane mirror that bends the optical path of the projected light beams 11, 11'' in order to reduce the external dimensions of the device.

The projector 7 includes projection tubes 5R and 5G for the left eye.

5B and projection lenses 6R, 6G, 6B, right eye projection tubes 5R'', 5G', 5B' and projection lenses 6R'', 6
G' and 6B' are arranged one above the other. In addition, as shown in FIGS. 2(a) and (b), the projection lens 6R
, 6G, 6B, and a polarizing filter 8 in front of the projection lenses 6R', 6G', 6B'.
.degree. are respectively attached and arranged on the support frame 9. In addition,
Since the support frame 9 is fixed to a rotatable shaft 10, it can rotate around the shaft 10.

The polarizing filter 8 transmits the left eye projection light 11 to the polarizing filter 8.
The right-eye projection light 11' is polarized, and a linear polarizing plate is used in each case.

In the polarizing filter 8, the azimuth angle of the polarization plane of the linear polarizing plate is +45
9, the polarizing filters 8' are each set such that the azimuth angle of the polarization plane of the linear polarizing plate is 145°, and the polarization planes of the linear polarizing plates are orthogonal to each other.

Note that the polarization plane of a linearly polarizing plate is the polarization plane of the linearly polarizing plate and the electrical vibration plane of the linearly polarized light (polarization plane of linearly polarized light) when linearly polarized light is incident on the linearly polarizing plate. )
This is the surface on which the transmittance of incident linearly polarized light is maximized when the In FIG. 2(b), the polarization plane of the linearly polarizing plate is indicated by an arrow.

Therefore, the polarization plane of the left-eye projection light 11 that has passed through the polarizing filter 8 and has been polarized has been 90' from each other.
It will be different.

Thereafter, the left-eye projection light 11 polarized by the polarizing filter 8 and the right-eye projection light 11' polarized by the polarizing filter 8'' are converted into ξ
The optical path is bent by 2, and a left-eye image and a right-eye image are formed on a transmission screen 13 supported by a housing 15.

On the transmission screen 13, a chronologically continuous left-eye image and a right-eye image are simultaneously projected in parallel, and these images are projected with the azimuth angle of the polarization plane of the polarizing plate being +45°.
, -45° polarized glasses 16, the left-eye image and right-eye image can be viewed independently. That is, the left eye projection light 11 transmitted through the transmission screen 13
Since the plane of polarization matches the polarizing plate for the left eye of the polarized glasses 16, it is transmitted without being absorbed by the polarizing plate for the left eye and reaches the left eye, but the polarizing plate for the right eye of the polarized glasses 16 Since the planes differ by 90", the right eye polarizing plate absorbs and blocks the light and does not reach the right eye. On the other hand, the right eye projected light 11' has a polarization plane that matches the polarizing plate of the polarizing glasses 16. Therefore, the polarizing plate for the right eye passes through the polarizing plate for the right eye without being absorbed, and reaches the right eye.However, since the plane of polarization is 90' different from the polarizing plate for the left eye of the polarized glasses 16, it is absorbed and transmitted by the polarizing plate for the left eye. Therefore, the left-eye image enters the left eye, and the right-eye image enters the right eye, making it possible to reproduce a stereoscopic image with a sense of depth due to binocular parallax.

By the way, in general, when the screen is made of plastic, mechanical stress and strain peculiar to screen molding remain, resulting in anisotropy of refractive index (birefringence).

In this embodiment, if a plastic screen with such birefringence is used as the transmission screen 13, the following problem will occur.

That is, when the left-eye projection light 11 and the right-eye projection light 11', which have been linearly polarized by the polarizing filters 8 and 8', pass through the transmission screen 13, due to birefringence,
The left-eye projection light 11 and the right-eye projection light 11° cannot maintain their polarization planes and become elliptically polarized light.

In other words, when linearly polarized light is incident on the transmission screen 13, the linearly polarized light is divided into two orthogonal polarization components, an ordinary ray and an extraordinary ray, due to birefringence, and the velocity inside the transmission screen 13 increases. Since they are different from each other, a phase difference occurs between the two when they are emitted, and the combination of the two becomes elliptically polarized light.

The ellipticity and azimuth angle at that time (the azimuth angle in this case is the angle between the principal axis of the ellipse and the incident polarization plane) are determined by the birefringence of the transmission screen 13, that is, the normal light output from the transmission screen 13. It depends on the relative phase difference (retardance) between the ray and the extraordinary ray.

When the left eye projection light 11 and the right eye projection light 11', which have become elliptically polarized lights, are viewed using polarized glasses 16, part of the left eye projection light enters the right eye, and a part of the right eye projection light enters the right eye. enters the left eye, making it impossible to reproduce stereoscopic images based on binocular parallax, resulting in ghosting in which images appear double.

Therefore, in this embodiment, as the transmission screen 13,
A plastic screen with low birefringence is used.

That is, for example, a screen molded from ultraviolet curable resin is used. In the case of this screen, highly fluid resin is poured into a mold, and the resin is irradiated with ultraviolet rays to harden and mold, so the mechanical stress strain during screen molding is small, and the birefringence of the screen can be reduced. No ghosting occurs in 3D images.

In addition, a screen formed by extrusion molding or hot press molding of a resin plate such as polymethyl methacrylate resin is used. In the case of this screen, stress strain during molding tends to remain on the resin plate, so depending on the molding conditions, the screen has a lot of birefringence, which can cause ghosts in J-3D images. However, as a molding condition, the birefringence of the screen is Jn (the axial refractive index n of the ordinary ray of linearly polarized light incident on the screen).
.

and the axial refractive index n2 of the extraordinary ray: Δn=nz
fl+)+ When the thickness of the screen is d and the wavelength of the incident ray is λ, the relative phase difference (retardance) between the ordinary ray and the extraordinary ray exiting the screen is δ−Δn−d
If it is set to be less than λ/(10π) (π#3.14), the ghost on the screen can be made below the detection limit and it can be used.

Note that in order to reduce the birefringence of the screen, it is also effective to release the mechanical stress strain by annealing the screen after molding.

Next, the operation when reproducing a non-stereoscopic image in this embodiment will be explained using FIG. 1(b).

In FIG. 1(b), a signal source 1 is, for example, a videotape player as a signal source for non-stereoscopic television. A non-stereoscopic video signal output from a signal source 1 is supplied to an input terminal 2.

The mode switch 14 is used to select between stereoscopic video reproduction and non-stereoscopic video reproduction, and when non-stereoscopic video is to be reproduced, the mode switch 14 is switched to the non-stereoscopic video reproduction side. Then, the contacts 3B and 30 of the switch 3 are electrically connected, and the support frame 9 of the polarizing filter 8.8'' rotates around the shaft 10, thereby connecting the polarizing filter 8.8'' to each of the projection lenses 6R and 6G. , 6B and projection lens 6R', 6
It operates to remove it from the front of G'6B'.

On the other hand, the video signal of the non-stereoscopic image supplied to the input terminal 2 is supplied to the signal circuit 4' through the signal circuit 4 and the contacts 3B and 3C of the switch 3, and as a result, the projection tube 5R, 5G.

5B, and projection tubes 5R', 5G', and 5B' are driven by the same non-stereoscopic video signal.

Therefore, the projection lenses 6R, 6G, 6B and the projection lenses 6R", 6G', 6B" project the same image content onto the transmissive screen 13 by projecting light 18.18 degrees. The brightness is the sum of the brightness due to the projected light 18 and the brightness due to the projected light 18°.

Note that when playing back non-stereoscopic images, it is not necessary to use the polarized glasses 16 shown in FIG. 1(a).

As described above, in this embodiment, the support frame 9 holding the polarizing filter 8° and 8° is used as the projection lenses 6R and 6G.

6B and the front surfaces of the projection lenses 6R', 6G', and 6B', the projected light 18.18'' is not absorbed by the polarizing filter 8.8''.

Therefore, as a polarizing filter of 8.8 degrees, the transmittance is about 4.
1% linear polarizing plate (for example, 01220 manufactured by Nitto Denko
DU), the polarizing filters 8, 8゛ are the projection lenses 6R16G, 6B and the projection lenses 6R', 6G'',
Transparent screen 13
It becomes possible to improve the brightness of the image by approximately 2.4 times.

In addition, in this example, the azimuth angle of the polarization plane of the linear polarizing plate in the polarizing filter 8° and 8° is set to +45°, respectively.
, -45°, but there is no need to be limited to this. For example, if the azimuth angle of the polarization plane of the linear polarizing plate is set to 0", 90@, etc., the polarizing filter 8 and the polarizing filter 8 It is only necessary to set the values to be relatively different from each other by 90''.

Furthermore, in this embodiment, linearly polarizing plates are used as the polarizing filters 8, 8', but circularly polarizing plates may be used instead. For example, a counterclockwise circularly polarizing plate may be used as the polarizing filter 8 for the left eye. By using clockwise circularly polarizing plates as the 8° polarizing filter for the right eye, stereoscopic images can be similarly reproduced.

FIG. 3 is an explanatory diagram showing the configuration of a projection type 3D video playback device as another embodiment of the present invention, in which (a) shows the state when playing back a 3D video, and (b) shows a state when playing back a non-3D video. Each shows the state during playback.

In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals.

In FIGS. 3(a) and 3(b), the signal source 1 is, for example,
Left eye signal R and right eye signal R, which are video signals for stereoscopic images
This is a video disc player that plays back video signals from an optical disc on which 3D images are recorded, or from an optical disc on which non-stereoscopic video signals are recorded.

First, in this embodiment, the operation when reproducing a stereoscopic image will be explained using FIG. 3(a).

In FIG. 3(a), the signal source 1 is reproducing a video signal from an optical disk on which left-eye signal R and right-eye signal R, which are video signals of stereoscopic video, are recorded, and the reproduced left-eye signal and the right eye signal R are switched alternately in a time-sharing manner,
The signal is supplied from the signal source 1 to the projector as one time-division signal.

The projector 7 includes three projection tubes 5R, 5G, and 5B for red, green, and blue, and three projection lenses 6R, 6G.
, 6B, and the ceiling 30 is
Fixed. In addition, the projection tube 5R of the projector 7
, 5G, 5B and the front surfaces of the projection lenses 6R, 6G, 6B are each provided with a polarizing filter 8. Polarization axis converter 23R, 23G
, 23B are arranged and held by the support frame 9.

Note that the support frame 9 is fixed to a rotatable shaft 10,
It can rotate around an axis 10.

In the polarizing filter 8, the azimuth angle of the polarization plane of the linear polarizing plate is +4
Therefore, the linearly polarized light transmitted through this polarizing filter 8 has an azimuth angle of the polarization plane of +
It becomes 45°. In addition, polarization axis converters 23R, 230, 2
3B is twisted nematic liquid crystal or PLZT (
Lead LanthanuraZirconate
Tintanate; Pb, La, Zr, T
The azimuth angle of the plane of polarization of the linearly polarized light transmitted through the polarizing filter 8 is converted using a transparent ferroelectric material (made of metal element i) or the like.

That is, when no control voltage is applied to the polarization axis converters 23R, 23G, and 23B, the incident linearly polarized light is emitted without changing the azimuth angle of the polarization plane at +45°.

On the other hand, when a control voltage is applied to the polarization axis converters 23R, 223G, and 23B, the polarization plane of the incident linearly polarized light rotates, and its azimuth changes by about 90'' and is emitted at -45°. Therefore, the polarization axis converter 23R, 2
By switching between the left eye signal [and the right eye signal R in the signal source 1] in synchronization with the switching operation of the azimuth of the polarization plane in 3G and 23B, the polarization axis converter 2
From 3R, 23G, and 23B, left-eye projection light and right-eye projection light are emitted alternately in a time-division manner, and the azimuth angles of their polarization planes differ by 90 degrees.

The projected light emitted from the polarization axis converters 23R, 23G, and 23B is projected onto a reflective screen 33 made of, for example, an aluminum film installed on the wall 31, and an image for the left eye is displayed on the reflective screen 33. and right-eye images are formed alternately in a time-sharing manner.

For the viewer, the azimuth angle of the polarization plane of the polarizing plate is +45° -45°
The user views the image projected on the reflective screen 33 using polarized glasses 16 set to . Then, polarized glasses 16
Since the polarization plane of the left-eye polarizing plate is set to match the polarization plane of the left-eye projection light, the left-eye projection light enters the left eye without being absorbed by the left-eye polarizing plate.

On the other hand, since the polarization planes of the left-eye projection light and the right-eye polarization plate of the polarized glasses 16 differ by 90" in azimuth, the left-eye projection light is absorbed and blocked by the right-eye polarization plate, and enters the right eye. Similarly, the right-eye projection light enters only the right eye and never the left eye.

In the end, the left-eye image and the right-eye image, which are time-divided and alternately projected, are incident only on the left eye and only on the right eye, respectively, so it is possible to reproduce a stereoscopic image with a sense of depth due to the binocular parallax.

Next, the operation when reproducing a non-stereoscopic image in this embodiment will be explained using FIG. 3(b).

In FIG. 3(b), signal source 1 is reproducing a video signal from an optical disk on which a non-stereoscopic video signal is recorded, and the reproduced non-stereoscopic video signal (normal video signal) is continuous. The signal is then supplied to the projector from the signal source l.

The projector 7 is also provided with a mode discrimination circuit (not shown), which discriminates whether the supplied video signal is a stereoscopic video signal or a non-stereoscopic video signal.

If the supplied video signal is a non-stereoscopic video signal, the mode discrimination circuit outputs a control signal to move the support frame 9 to which the polarization axis converters 23R, 23G, 23B and the polarization filter 8 are fixed. It rotates around the shaft 10 and moves the entire support frame 9 upward.

With this control, when a non-stereoscopic video signal is input to the projector 7, the projection lenses 6R, 6G, 6
Since the polarization axis converters 23R, 123G, 23B and the polarization filter are removed from the front of B,
The projection lights emitted from the projection tubes 5R, 5G, and 5B are not absorbed by the polarization filter 8 and the polarization axis converters 23R, 23G, and 23B, and a bright image can be obtained on the reflective screen 33.

That is, for example, in this embodiment, a polarizing filter with a transmittance of 41% is used as the polarizing filter 8, and the polarizing axis converter 23R
, 23G, and 23B are respectively used as polarization axis converters with a transmittance of 70%.
Compared to the case where the screen is not removed from G and 6B, it is possible to increase the screen brightness by approximately 3.7 times.

In this example, the azimuth angle of the polarization plane of the linear polarizing plate in the polarizing filter 8 was set to +45".
There is no need to be limited to this.

Further, in this embodiment, a linearly polarizing plate is used as the polarizing filter 8, but a circularly polarizing plate may be used instead.

FIG. 4 is an explanatory diagram showing the bottom of a projection type stereoscopic image reproducing apparatus as another embodiment of the present invention, in which (a) shows the state when reproducing a stereoscopic image, and (b) shows a state when a non-stereoscopic image is reproduced. Each shows the state when playing. Further, FIG. 5 is a front view showing the projector section in FIG. 4.

In FIGS. 4 and 5, the same parts as in FIGS. 1 and 2 are given the same reference numerals.

This embodiment differs from the embodiment shown in FIG. 6
Three polarizing filters 8R, 80, 8 whose polarization planes of linear polarizing plates have different azimuthal angles in one-to-one correspondence with G and 6B.
In addition, three polarizing filters 8R", 8G', 8B" whose polarization planes of linear polarizing plates have different azimuthal angles correspond one-to-one to the projection lenses 6R", 6G', 6B',
These are the points where each is placed.

In this embodiment, the operation when playing back a non-stereoscopic image is as follows:
Since it is similar to the embodiment shown in FIG. 1, its explanation will be omitted. Furthermore, since the basic parts of the operation when reproducing a stereoscopic image are the same as those in the embodiment shown in FIG. 1, only the parts that are different from the embodiment shown in FIG. 1 will be described below.

In general, a transmission screen in a rear projection type video playback device is often constructed by combining a lenticular screen made of plastic and a Fresnel screen also made of plastic. Moreover, the lenticular screen is manufactured by extrusion molding a resin plate such as polymethyl methacrylate resin, and the Fresnel screen is manufactured by hot press molding the resin plate.

As mentioned above, in the case of a screen made by extrusion molding or hot press molding of a resin plate such as polymethyl methacrylate resin, stress strain during molding tends to remain in the resin plate, resulting in birefringence. In particular, in the case of the above Fresnel screen,
Stress and strain during molding tend to remain in the peripheral area, causing birefringence. Therefore, the left eye projection light 11 becomes linearly polarized light.
When the right-eye projected light 11' passes through the periphery of this Fresnel screen, the plane of polarization cannot be maintained due to its birefringence, and it becomes elliptically polarized light. As described above, when the left-eye projection light 11 and the right-eye projection light 11° become elliptically polarized light, there is a problem in that a reproduced stereoscopic image produces a double ghost.

Therefore, in the embodiment shown in FIG. 1 described above, such a problem was dealt with by limiting the molding conditions. In contrast, this embodiment deals with this by providing a phase plate 17.

That is, in this embodiment, two sheets are used as the transmission screen 13: a lenticular screen made by extrusion molding a resin plate such as polymethyl methacrylate resin, and a Fresnel screen also made by hot press molding. In particular, the Fresnel screen has birefringence in its periphery.

On the other hand, the phase plate 17 is made of a transparent plastic film (for example,
It is an optically birefringent material made of a thin film of oxidized cellulose, and when linearly polarized light enters it, it separates into two orthogonal polarized components, an ordinary ray and an extraordinary ray (both linearly polarized) and emits them. Note that the relative phase difference (retardance) between the emitted ordinary ray and the extraordinary ray can be controlled by stress strain applied to the phase plate 17.

FIG. 6 is a characteristic diagram showing the relationship between the transmissive screen shown in FIG. 5, the phase plate polarity δ, and the distance r of the transmitted projection light from the optical axis.

In FIG. 6, the broken line represents the transmission screen 13, and the solid line represents the phase plate 17. Note that the distance r is
The position of the optical axis of the transmitted projection light (that is, the center of the screen surface of the transmission screen 13, and the center of the plate surface of the phase plate 17) is set to O.

The transmission type screen 13 has a large stress strain at the periphery when forming the Fresnel screen described above, so as shown in FIG.
It exhibits the characteristic that its retardance increases gradually.

On the other hand, as shown in FIG. 6, the phase plate 17 has a retardance with a sign opposite to that of the transmissive screen 13, and the retardance gradually increases from the center to the periphery of the plate surface. It exhibits the property of increasing.

Therefore, polarizing filters 8R, 8G, 8B.

When the left-eye projection light 11.right-eye projection light ll'', which has become linearly polarized light and has emitted 8R', 8G'', and 8B°, passes through the phase plate 17, it becomes elliptically polarized light due to its birefringence. Then, the left-eye projection light 11. which has become elliptically polarized light has been emitted from the phase plate 17. The projection light 11 for the right eye is projected onto the transmission screen 13.
Since the signs of the retardance of the phase plate 17 and the retardance of the transmissive screen 13 are opposite, the phase difference is canceled and the left-eye projection light 11. is linearly polarized from the transmissive screen 13. Right-eye projection light 11' is emitted.

Therefore, when the polarized glasses 16 are used, the left-eye image and the right-eye image can be separated, and a stereoscopic image with a sense of depth without ghosts can be reproduced.

By the way, in the embodiment shown in FIG.
The projected light 11 for the left eye that has passed through the polarizing glasses 16 has a polarization plane 90" different from that of the polarizing plate for the right eye, so it is absorbed and blocked by the polarizing plate for the right eye and does not reach the right eye. As described above, the projected light 11 for the right eye has a plane of polarization different by 90 degrees from the polarizing plate for the left eye of the polarized glasses 16, so it is absorbed and blocked by the polarizing plate for the left eye and does not reach the left eye.

However, in reality, the left-eye projected light 11 and the right-eye projected light 11' are completely absorbed and blocked by the polarizing plates of the polarized glasses 16, even if their planes of polarization differ by 90 degrees. It doesn't necessarily mean that it will happen. That is, depending on the wavelength of the light included in the left-eye projection light 11 and the light included in the right-eye projection light 11'',
A portion of the light may be transmitted without being absorbed or blocked by the polarizing plate.

This means that all the light is absorbed and blocked by the polarizing plate.
This is because the angle between the polarization plane of the polarizing plate and the polarization plane of light is not constant at 90°, but varies slightly depending on the wavelength of the light.

Therefore, in this embodiment, as described above, the projection lens 6
Of the left-eye projection light 11 that has emitted R, 6G, and 6B, the red light is filtered by the polarizing filter 8R, the green light is filtered by the polarizing filter 8G, and the blue light is filtered by the polarizing filter 8B. Of the left-eye projection light 11' which is polarized and output from the projection lenses 6R"6G', 6B", the red light is filtered by the polarizing filter 8R", and the green light is filtered by the polarizing filter 8G', and the blue light is polarized by the polarizing filter 8R". The light was polarized by a polarizing filter 8B'.

Then, out of the left-eye projection light 11 that has passed through the transmission screen 13, all of the red light, green light, and blue light are polarized so that they are absorbed and blocked to the maximum extent by the right-eye polarizing plate of the polarized glasses 16. Each polarizing filter 8
While adjusting the azimuth angles of the polarization planes of the linear polarizing plates in R, 8G, and 8B respectively, among the right eye projection light 11゜,
red light.

The linear polarizing plates in each polarizing filter 8R'8G', 8B' are arranged so that the polarizing plane is such that both green light and blue light are maximally absorbed and blocked by the left eye polarizing plate of the polarized glasses 16. The azimuth angle of each polarization plane can be adjusted.

As a result, when viewing the left-eye image and right-eye image projected on the transmissive screen 13 using the polarized glasses 16,
The left eye projection light 11 transmitted through the transmission screen 13 is
Most of the projected light 11 for the right eye is absorbed and blocked by the polarizing plate for the right eye of the polarized glasses 16 and does not reach the right eye. It is absorbed and blocked, preventing it from reaching the left eye.

In each of the above embodiments, the projector 7 having a projection tube is used as the projector, but it is clear that a liquid crystal projector having a liquid crystal display panel may be used instead of the projector 7. .

〔Effect of the invention〕

According to the present invention, by using a transmissive screen and projecting a left-eye projection light and a right-eye projection light from the back of the transmissive screen to display a left-eye image and a right-eye image, respectively, external light can be reduced. It is possible to reproduce high-contrast 3D images without being affected.

Furthermore, when a plastic screen is used as the transmission screen, birefringence caused by residual mechanical stress and strain during screen molding may cause ghosts to appear double in the reproduced 3D image. However, according to the present invention, a plastic transmission screen with low birefringence obtained by optimizing the molding method, molding conditions, or post-molding treatment,
This problem can be solved by using

Further, even when a screen with birefringence is used as a transmission screen made of plastic, the above problem can be solved according to the present invention by using a phase plate that compensates for the birefringence of the screen. can. Note that in this case, manufacturing of the screen becomes easier.

Further, according to the present invention, even when reproducing non-stereoscopic images, sufficient screen brightness can be obtained, and the images can be viewed on a bright screen.

[Brief explanation of drawings]

FIG. 1 shows a projection type solid Jlk- as an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing the configuration of a projection type 3D video reproduction device as another embodiment of the present invention, and FIG. 4 is an explanatory diagram showing the configuration of a projection type 3D video reproduction device as another embodiment of the present invention. Figure 5 is a front view showing the projector section in Figure 4, and Figure 6 shows the retardance δ of the transmission screen and phase plate in Figure 5, and the distance r of the transmitted projection light from the optical axis. It is a characteristic diagram showing the relationship. Explanation of symbols 1...Signal source, 3...Switch, 4.4"...Signal circuit, 5R, 5G, 5B, 5R'5G" 5B
'...Projection tube, 6R, 60, 6B, 6R"6G'6
B'...Projection lens, 8, 8°, 8R, 8G, 8B
, 8R', 8G", 88゛... polarizing filter, 9.
...Support frame, 10...Axis, 11...Left eye projection light,
11゛... Projection light for right eye, 13... Transmissive screen, 16... Polarized glasses, 17... Phase plate, 23R
, 23G. 23B...Polarization axis converter, 33...Reflection type screen.

Claims (1)

[Scope of Claims] 1. A first signal circuit that transmits a left-eye video signal to obtain a left-eye video, and a second signal circuit that transmits a right-eye video signal to obtain a right-eye video; a left-eye video display means that receives the transmitted left-eye video signal and outputs the left-eye projection light; and a right-eye video display means that receives the transmitted right-eye video signal and outputs the right-eye projection light. a transmission screen; a left-eye projection optical system that enlarges and projects the emitted left-eye projection light onto the transmission screen from the rear; and a left-eye projection optical system that enlarges and projects the emitted right-eye projection light onto the transmission screen from the rear. a right-eye projection optical system for projecting images, a left-eye polarizing filter disposed in front of the left-eye projection optical system to polarize the left-eye projection light, and a left-eye polarization filter disposed in front of the right-eye projection optical system for right-eye projection; a right-eye polarizing filter that polarizes the projected light;
A projection type stereoscopic image, characterized in that a stereoscopic image can be reproduced by displaying the left-eye image using the projected left-eye projection light and displaying the right-eye image using the right-eye projection light, respectively. Video playback device. 2. In the projection type stereoscopic image reproduction device according to claim 1, the left-eye image display means and the right-eye image display means:
A projection type three-dimensional image reproduction device comprising a projection tube or a liquid crystal display panel, respectively. 3. The projection type stereoscopic image reproducing apparatus according to claim 1 or 2, wherein the transmission screen is made of plastic. 4. The projection type stereoscopic image reproducing apparatus according to claim 3, wherein the plastic screen is formed by molding an ultraviolet curable resin. 5. In the projection type three-dimensional image reproducing apparatus according to claim 3, the plastic screen is formed by molding a resin plate, and as a result of the molding, when linearly polarized light is incident on the plastic screen, The difference obtained by subtracting the axial refractive index n_1 of the linearly polarized ordinary ray from the axial refractive index n_2 of the linearly polarized extraordinary ray is defined as the birefringence Δn of the plastic screen, and the birefringence Δn and When the product of the film thickness d of the plastic screen is the retardance δ of the plastic screen, the retardance δ is λ/(10π) [where λ is the wavelength of the incident light and π is the retardance δ of the plastic screen. A projection type three-dimensional image playback device characterized in that the circumference is less than or equal to [pi]. 6. The projection type stereoscopic image reproducing apparatus according to claim 5, wherein the plastic screen is made of polymethyl methacrylate resin. 7. The projection type stereoscopic image reproducing apparatus according to claim 3, wherein the plastic screen is formed by annealing after molding. 8. In the projection type three-dimensional image reproducing apparatus according to claim 3, a transparent plastic is provided in the optical path of the left-eye projection light and the right-eye projection light from the left-eye polarizing filter and the right-eye polarizing filter to the transmission screen. A projection type three-dimensional image reproducing device characterized in that a phase plate made of a thin film is arranged. 9. In the projection type three-dimensional image reproducing apparatus according to claim 8, the phase plate is an optical compound that, when linearly polarized light is incident, separates the linearly polarized light into two linearly polarized lights whose vibration directions are orthogonal to each other and outputs the two linearly polarized lights. It is a refracting body, and the relative phase difference between the two emitted linearly polarized lights gradually increases as the distance from a certain reference point increases in the direction along the plate surface of the phase plate. 3. A projection type three-dimensional image reproducing apparatus characterized in that the plate is arranged so that the optical axis of the projection light passing through the center point of the transmission screen passes through the reference point. 10. The manufacturing method for manufacturing the phase plate in the projection type stereoscopic image reproduction device according to claim 9, comprising the step of applying stress strain that gradually increases from the center to the periphery of the transparent plastic film. A method of manufacturing a phase plate. 11. A phase plate manufactured by the manufacturing method according to claim 10, wherein the transparent plastic film is made of oxidized cellulose. 12. A first signal circuit that transmits a left-eye video signal to obtain a left-eye video, a second signal circuit that transmits a right-eye video signal to obtain a right-eye video, and the transmitted left-eye video signal. A left-eye three primary color projection tube group consisting of at least a red projection tube, a green projection tube, and a blue projection tube, which input a video signal and output red, green, and blue projection lights, respectively, and the transmitted right-eye image. a right-eye trichromatic projection tube group consisting of at least a red projection tube, a green projection tube, and a blue projection tube, which input a signal and output red, green, and blue projection lights, respectively; a screen; and the left-eye trichromatic projection tube. a left-eye projection optical system group consisting of at least a red projection optical system, a green projection optical system, and a blue projection optical system for respectively enlarging and projecting the red, green, and blue projection lights emitted from the tube group onto the screen; , a right eye comprising at least a red projection optical system, a green projection optical system, and a blue projection optical system for respectively enlarging and projecting the red, green, and blue projection lights emitted from the three primary color projection tube group for the right eye onto the screen; a left-eye polarizing filter that is disposed in front of the left-eye projection optical system group and polarizes the red, green, and blue projection lights from the left-eye projection optical system group, and the right-eye projection optical system group; a right-eye polarizing filter disposed in front of the left-eye projection optical system group and polarizing the red, green, and blue projection lights from the left-eye projection optical system group, respectively; The left-eye image is projected by the red, green, and blue projection lights projected by the projection optical system group.
red and green projected by the right eye projection optical system group;
In a projection type stereoscopic image playback device that can play back a stereoscopic image by displaying the right eye image using the blue projection light, when playing back a non-stereoscopic image, the first and second signals are transmitting the same video signal to the circuit instead of the left-eye video signal and the right-eye video signal, and inserting the left-eye polarizing filter from the front of the left-eye projection optical system group;
A projection type three-dimensional image reproducing apparatus characterized in that each of the right-eye polarizing filters is removed from the front surface of the right-eye projection optical system group. 13. A red projection tube, a green projection tube, and a blue projection tube that input a stereoscopic video signal for time-divisionally obtaining images for the left eye and images for the right eye, and emit red, green, and blue projection lights, respectively. a three primary color projection tube group consisting of at least a screen; red and green light emitted from the three primary color projection tube group;
a projection optical system group consisting of at least a red projection optical system, a green projection optical system, and a blue projection optical system for respectively enlarging and projecting the blue projection light onto the screen; and a projection optical system group each disposed in front of the projection optical system group. , a polarizing filter that polarizes the red, green, and blue projected lights from the projection optical system group, and the azimuth angles of the polarization planes of the red, green, and blue projected lights polarized by the polarizing filters, respectively. a polarization axis converter group consisting of at least a red polarization axis converter, a green polarization axis converter, and a blue polarization axis converter that convert in synchronization with a control signal that is displayed on the screen; The red color projected by the projection optical system group,
In a projection type 3D image playback device capable of playing back a 3D image by displaying the left-eye image and the right-eye image in a time-sharing manner using the green and blue projection lights, when playing back a non-stereoscopic image. In this step, a non-stereoscopic image video signal is inputted to the three-primary color projection tube group instead of the stereoscopic image video signal, and the polarizing filter and polarization axis converter group are respectively input from the front of the projection optical system group. A projection type three-dimensional image playback device characterized in that it is detachable. 14. In the projection type 3D image reproduction apparatus according to claim 12 or 13, switching between reproduction of a 3D image and reproduction of a non-stereoscopic image is performed according to switching of a switch means, or is performed by superimposing the video signal on the video signal. What is claimed is: 1. A projection type three-dimensional video reproducing device characterized by detecting a specific signal, decoding it, and performing processing according to the decoding result. 15. In the projection type three-dimensional image reproducing apparatus according to claim 12, 13 or 14, the polarizing filter is composed of at least a red polarizing filter, a green polarizing filter, and a blue polarizing filter, and Polarizing filters, green polarizing filters, and blue polarizing filters are
1. A projection type three-dimensional image reproducing apparatus characterized in that each of the three-dimensional polarizing plates is made up of a linearly polarizing plate or a circularly polarizing plate, and arranged so that the azimuth angles of the respective planes of polarization do not match each other. 16. The left-eye video signal and the right-eye video signal are recorded from an optical disc in which information on a left-eye video signal and a right-eye video signal are spirally recorded in parallel as pit rows on a transparent resin plate. Obtained from an optical disc playback device that can read simultaneously using light of two different wavelengths,
A stereoscopic video reproduction system characterized in that a stereoscopic video is obtained using the left-eye video signal and the right-eye video signal.