JPH05107504A - Three-dimensional display device - Google Patents

Abstract

PURPOSE:To obtain a three-dimensional color moving image which is reduced in the number of picture elements. CONSTITUTION:The three-dimensional display device consists of plural display devices 101 for parallax image projection, projection lenses 102 corresponding to the display devices 101, a lens plate 103, a retroreflective screen 105 which is placed on the rear focus plane of the lens plate 103, and a conversion optical system. The display devices 101 for projection are used for multiple projection to obtain the effect which reduces the burden of the number of picture elements on each device. Further, a parallax image is automatically positioned on the screen 105, so a projection display image is only projected on the lens plate 103 and no absolute position precision is required. Further, plural pieces of display information are put together and recognized, so picture elements in a matrix shape are inconspicuous and a feeling of quality is superior. For a display signal, a parallax image which is required before need not be generated by spatial sampling and composition. A continuous three-dimensional visual field is secured and even projection display devices which are wide in interval can be employed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional display device utilizing binocular parallax.

[0002]

2. Description of the Related Art A conventional three-dimensional display device is described in the 1990 Conference on Image Engineering Conference, 11-4, pp. 213
-216 (1990), a lens plate (hereinafter, referred to as a lens plate) on which small elementary lenses are arranged is accurately aligned and projected, and a television conference technical report vol. 14, 67, pp. 1-6
(1990), IEICE Spring National Convention SD-3
As described in -17, the display device was in contact with the display element, and the pixel pitch of the display element and the pitch of the lens plate and the lens plate were adjusted for accurate alignment. The technical report of the Television Society, vol. 12, 35, pp. 53-5
8, as shown in VVI 88-42 (1989),
A film was used for the projection image display surface.

[0003]

However, in the conventional three-dimensional display device, the problem is that the lens plate on which the small elementary lens is arranged must be accurately aligned with the pixel, which is more than the number of pixels of the display device. , There is a problem that the obtained resolution is greatly reduced, and further, if the viewpoint moves greatly, stereoscopic vision becomes impossible. Therefore, in the present invention, it is an object of the present invention to relax the alignment accuracy by projecting a multiplexed image from a plurality of display elements whose projection positions are changed through a lens plate, and reduce the burden of the number of pixels of one display device. It is what It is also intended to obtain a 3D moving image and a 3D color moving image.

[0004]

A three-dimensional display device of the present invention is placed on a plurality of display devices for parallax image projection, a plurality of projection lenses corresponding to the display device, a lens plate, and a back focal plane of the lens plate. It is characterized by comprising a retroreflective screen.

Further, the plurality of display devices for parallax image projection are characterized by being matrix type liquid crystal display devices.

Further, the plurality of display devices for projecting the parallax image are characterized by being projection type display devices using liquid crystal.

Further, the plurality of display devices for parallax image projection are characterized by being liquid crystal display devices having an optical arrangement in which projection pixels are superposed on a screen.

The three-dimensional display device of the present invention comprises a plurality of display devices for projecting a parallax image, a plurality of projection lenses corresponding to the display device, a lens plate, a retroreflective screen placed on the back focal plane of the lens plate, It is characterized by comprising a conversion optical system for adjusting a projection lens interval in the display space.

Further, the conversion optical system is characterized by including a lens element whose optical axis is off.

[0010]

In the present invention, as shown in FIG. 1, a plurality of display devices 101 for projection and a plurality of projection lenses 10 corresponding to the display devices are provided.
2, the lens plate 103, and the retroreflective screen 105 placed on the back focal plane of the lens plate are the basic components. Reference numeral 106 denotes illumination light that illuminates the display device. In such a multi-view three-dimensional display device, the reproduced image point 104 is spatially determined by observing the image corresponding to the binocular parallax of the observer through one screen, and a three-dimensional feeling is obtained. Is. In the device of the present invention, since the light flux from the projection display device exhibits recursiveness on the screen, the light fluxes of the right eye and the left eye that form one reproduction image point are automatically output from the projection display device that displays two parallax images. Can be spatially sampled and selected. On the other hand, when the display image is arranged on the back focal plane of the lens plate, it is necessary to spatially sample the parallax images and arrange them in order as shown in FIG. For this reason, the performance of the display device required to obtain the same three-dimensional reproduced image has the same pixel density as that of the lens plate in the present invention.
The conventional case of FIG. 2 requires a pixel density which is several times that of the lens plate. Further, according to the present invention, since the parallax images are automatically aligned by projecting the parallax images on the screen, only the alignment accuracy between the projected display images is required. The parallax image must correspond to each element lens of the plate with extremely high accuracy, and the projection display image requires absolute positional accuracy with respect to the lens plate. As described above, according to the present invention, the requirement for the position accuracy of the projection display device is relaxed, and the display signal does not need to be spatially sampled and then combined to form a parallax image.

The present invention will be described in detail below with reference to examples.

[0012]

【Example】

(Embodiment 1) FIGS. 3 and 4 are a schematic view and an elevation view of a three-dimensional display device of the present invention, respectively. The display device for projection is a horizontal one-dimensional array using a monochrome liquid crystal display device 301 (hereinafter, referred to as LCD) driven by a thin film transistor (hereinafter, referred to as TFT). Lens plate is lenticular screen LS 302
Was used. The reflective screen is aluminum coated with diffuse reflectivity and adhered to the focal point of the lens plate.
Reference numeral 303 is a convex mirror for apparently reducing the distance between the projection LCDs. Reference numeral 304 denotes a projection lens L1 arranged on each LCD, which is a LCD together with a Fresnel lens FL 305 installed to secure a continuous viewing area and to remove the optical axis.
Form an image on the screen. The Fresnel lens and the convex mirror form a conversion optical system.

Illumination of the LCD is a halogen lamp LP 3
06, heat ray cut filter, condenser lens L2
Parallel light was made incident on the LCD by an illuminating device composed of 308 and a forced air cooling device FN 307 to prevent display unevenness due to the incident angle of the light flux on the LCD. The ES 309 is an LCD control / signal processing circuit, and the CL 310 is a signal cable from the image pickup device. The observer observes the image displayed near the LS through the convex mirror CM. Table 1 shows an actual example of the configuration used in this example.

[0014]

[Table 1]

Next, the operation of the apparatus of this embodiment will be briefly described. Parallax image signal (here, LC with the viewpoint changed horizontally)
Video signals for D channels) to independent LCD groups,
Each LCD displays an image of an object viewed from a position slightly shifted from the viewpoint. The displayed images are arranged in a line in the horizontal direction and projected so as to overlap one on the screen. In this embodiment, the projection optical system is formed by the projection lens corresponding to each LCD and the conversion optical system (the Fresnel lens and the convex mirror with the optical axis removed). Due to the recursive nature of the lenticular screen, the image seen by the right eye becomes an LCD image corresponding to the image seen from the viewpoint of the right eye. The same applies to the left eye. Then, as the viewpoint is shifted, the LCD image is sequentially shifted to correspond to the moving direction of the viewpoint. Therefore, in order to obtain a smooth image shift without jumping and a wide viewing area with respect to the movement of the viewpoint, it is necessary to arrange a large number of projection display devices in the same manner as the angle change corresponding to the movement of the viewpoint. For this purpose, it is desirable that the LCD be smaller than the distance between the two eyes of a person, but in reality, the size of the LCD is limited and a space for wiring is required, and the distance becomes large. In order to realize this, in this embodiment, a projection lens group arranged at a small interval, a corresponding projection display device, and a conversion optical system are used. As a projection display device, a small LCD driven by a polysilicon TFT having a driver circuit built in the same glass substrate is used to narrow the interval. Further, in this embodiment, 12-channel LC with 320 × 220 pixels is used.
Although D is used, if a conventional method is used to form a three-dimensional display device having the same performance as D, a display device having a pixel density of 12 times in the horizontal direction is required. Furthermore, in the conventional method, the spatially sampled 12-ch parallax images must be accurately matched in the element lens of the lens plate.
The lens plate is required to have extremely high accuracy. In the case of the present embodiment, it is only necessary to project the LCDs on the screen multiple times, and no alignment precision is required for the lens plate. Further, since the LCD itself has matrix pixels with high positional accuracy, there is an advantage that relative positioning accuracy between the projected images can be easily performed. In addition, the video signal of the parallax image is LC
If it is input to D, it is not necessary to perform sampling and synthesis to create a display signal.

Each component will be described in more detail. First, the conversion optical system will be described. In this embodiment, in order to secure the depth of the continuous viewing zone, a Fresnel lens and a convex mirror are used.
It uses a conversion optical system consisting of two CMs. Each LC
When the distance D is compared with the distance between both eyes of a person (about 64 mm), the distance is a little too large, and if it is left as it is, the image jumps and the continuous visual field cannot be obtained. In such a case, it is more important to match the human visual performance even if the viewing area is slightly reduced. These discontinuities are described in Journal of Television Society, vol. 44, N
o. 5, pp. As described in 598-607, a projection lens array (hereinafter, referred to as a phase point array) and a lenticular screen element lens in a space in which an observer who is a receiver of image information exists (hereinafter, referred to as a display space). It is known that it is determined by the positional relationship with the central array (hereinafter referred to as the recording point array).

FIG. 5 illustrates the optical system placed in front of the projection lens array. In FIG. 5A, the C surface is the projection lens center array surface, the E surface is the recording surface, and the A surface is the surface (LCD display surface) on which the parallax image group is reproduced. LC is #
It is a conversion optical system that is arranged between the 1st and 2nd planes and is composed of a large-diameter lens system whose optical axis is the Z axis.

When illuminating the A surface from the left, the light ray P ₁ passing through one of the projection lenses and passing through the # 1 surface is converted by LC, and becomes P ₂ when exiting the # 2 surface. Due to the action of the lenticular screen, the 3D image appears near the E surface (OB). Since the observer is in the same space as the E plane, the image seen by the observer is also (OB). However, the point where the extension of the light rays projected on the E surface gathers is the image plane of the C surface when the C surface is seen from the E surface through the conversion optical system LC in FIG.
This is a point on the C'plane shown in FIG. 5 (b). Therefore, the phase point plane in the observation space is the C'plane, and its position and the phase point interval are u ₀ and c'in the figure. Although the drawing shows the case where the LC is a magnifying optical system, c'is smaller than the projection lens interval c in FIG. 5A when the LC is a reducing optical system. As described above, the optical system used in this embodiment is a phase point reduction optical system for the observer. In the phase point conversion, it is desirable for the observer to have the phase points appear at positions with good binocular visibility at appropriate intervals c '. On the other hand, for the projection display device, the parallax image must be formed on the lenticular screen surface E. Therefore, in such a conversion optical system, it is necessary to simultaneously satisfy the two conditions of appropriate conversion of the phase point interval and formation of parallax images.

FIG. 6 is an explanatory view when a two-lens system is used for conversion of the phase point surface. FIG. 7 is a diagram for obtaining a focal length and a lens interval of two lenses when the above two conditions are simultaneously satisfied. On the imaging side, it is assumed that the parallax image group is obtained by the lens array and the conversion optical system that are focused on infinity as in the present embodiment. When one lens L1 (f ₁ ) is placed immediately before the projection lens array focused on infinity on the display side, and another lens L2 (f ₂ ) is placed at the front distance d. , The horizontal axis of FIG. 7 is the enlargement ratio M (= c '/ c) of the phase interval, and the vertical axis is the normalized distance u ₂ / u ₀ (see FIGS. 5 (a) and 5 (b)). Indicates the phase point position. The drawn solid line, the short broken line and the long broken line represent the focal lengths f ₂ (α) and f ₁ (β) of the _two lenses, respectively.
And the lens spacing d (γ) are represented by the normalized angles α, β, γ.

Note that f ₁ (β) = u ₀ cot β, f ₂ (α) = u ₀ cot
α, d (γ) = u ₀ cotγ, F = u ₀ / M The unit is degree.

The reproduced parallax image on the A surface and the projected image on the E surface.
The image magnification with respect to the reproduced image is -u ₀ / (fM).
Here, f is the focal length of the projection lens shown in FIG. The enlargement ratio of the 3D image is the product of the enlargement ratio in the imaging system (usually a reduction system) and -u ₀ / (fM).

As an example, the phase point side is a convex lens, the recording point side is a concave lens, and the absolute values of the focal lengths are both 1100 m.
If it is desired to obtain the phase point surface at a position of m, the distance u ₀ = 1100 mm in front of the recording surface, referring to FIG. 6, -α = β = 45 °. In FIG. 7, when the value at the intersection of the curves of α = −45 ° and β = 45 ° is read, γ = 31.7 °, u ₂ / u ₀ = 0.62, M = 0.62 is obtained. Therefore, it is predicted that the phase point interval expansion ratio M is 0.62, and the distance u ₂ from the concave lens on the recording point side to the phase point surface and the required lens interval d are u ₂ = 680 mm and d = 680 mm, respectively.

In the conversion system of this embodiment designed in this way, there is a convex lens (L1 (f ₁ ), Fresnel lens) at a position about 120 mm away from the projection lens array surface, and a concave lens (L2 (f ₂ )). ) Was used instead of the convex mirror. Its value is u ₂ = 65
0mm, d = 550mm, u ₀ = 1100mm, f ₁ = 1100mm, f ₂ = -1100mm, M = 0.
73.

Further, in order to remove the significant distortion due to the lens shape irregularity at the center of the Fresnel lens FL and to reduce the incident angle to the lenticular screen LS, the use of the center of the Fresnel lens is avoided and the Fresnel lens The part deviated from the center by about 160 mm is used. This is because the optical axis of the conversion optical system is vertically displaced from the plane formed by both eyes and the center of the screen so that the light flux directed from the screen to the eye does not overlap with the light flux directed from the projection display device to the screen.

Next, regarding the screen, in this embodiment,
Image softness rather than reflective recursive performance. Emphasizing the value, a highly diffused one was used. The lens pitch should be smaller than the pixel pitch of the projected image, and preferably has a pitch twice or more the pixel pitch. This is because the display information of the projection display device is not damaged by the lens plate.

The LCD and its illuminating device used in this embodiment are the most important elements of this display device. Its design
The points of adjustment are as follows.

1) It is desirable that the LCD be small and have high resolution and high contrast.

2) The variations in the electrical and optical characteristics of the LCD are small.

3) It is important that the light source is a compact one that can obtain white parallel light, and that the temperature of the LCD does not rise.

4) Illumination luminous flux direction, projection lens center position, L
It must have a mechanism for adjusting the rotation of the CD around the optical axis and for adjusting the polarization direction of the polarizing plate.

The electrical adjustment is closely related to the polarization direction adjustment and the illumination light flux direction adjustment. Contrast and latitude are common problems in two-dimensional image display, but brightness uniformity and color uniformity between parallax images, and mutual alignment are especially necessary in three-dimensional image display.

Adjusting the direction of the two polarizing plates in front of and behind the LCD,
LCD bias voltage adjustment, signal voltage adjustment, and illumination luminous flux direction adjustment make the LCD evenly bright, the contrast of the two-dimensional image is high, and the color of the transmitted light is white or similar. To do. The presence of LCD color variations is undesirable for binocular vision. The variation in the brightness of the LCD transmitted light is not preferable for binocular vision. LC
If the variation in brightness cannot be avoided due to the variation in D, adjust the variation within 3 dB by adjusting the signal voltage amplitude, adjusting the light source brightness, and filtering. In this embodiment, the transmission polarization directions are aligned horizontally in order to reduce the reflection loss on the convex mirror and the screen. For the variation in brightness, the projection light from each LCD may be monitored and feedback control may be applied to the light source and the LCD drive signal.

The alignment of the parallax images is made by optical adjustment. Place all parallax image channels with the same standard video test signal. Place a Fresnel lens in front of the projection lens array,
First, for each channel, the depth distance of each projection lens is adjusted so that a clear image appears on the focal plane of the Fresnel lens. Next, the LCD mounting frame is adjusted so that each horizontal axis of the LCD is horizontal. Then, a plurality of parallax image channels are simultaneously used to adjust the lateral position of the projection lens so that the parallax images are best overlapped.

In this way, a moving image 3D image could be observed on the other side of the lenticular screen.
In the case of this embodiment, the phase point spacing in the display space is about 35 mm,
Phase point position is about 1100 mm in front of the lenticular screen
It is in. The depth of field is approximately 600 mm to 4000 mm or more in front of the lenticular screen. In the range of the viewing area, a three-dimensional image magnified about 160% of the size of the subject is obtained. In the obtained three-dimensional image, since the image information of a plurality of LCDs is combined and recognized, the matrix-shaped pixels are less noticeable and the texture is excellent.

Further, the main axis direction of the image pickup optical system is linear, whereas the display optical system is bent by the Fresnel lens and the convex mirror, so that the displayed 3D image is slightly distorted. This is mainly considered to be the aberration of the Fresnel lens and the aberration of the projection lens. However, it can be solved by adjusting the image pickup optical system to the display optical system or by giving image correction distortion to each parallax image before displaying.

The binocular resolution of the displayed 3D image is LC
It was observed to be improved compared to the roughness of the resolution of D (320 × 220). If the parallax images are perfectly aligned, the horizontal resolution has display information for both eyes, so the LCD
Theoretically, it is improved about twice as much as the single unit.

The display signal of this embodiment was obtained from an image pickup device composed of multiple CCD cameras. The imaging lens array is a horizontal one-dimensional array focused at infinity. Furthermore, each L
It was sent to the CD as a baseband signal for each channel.

(Embodiment 2) Embodiment 2 is the LCD of Embodiment 1.
This is an embodiment in the case where an LCD with a color filter is adopted in the above. Since the actual device configuration is the same as that of the first embodiment, the description is omitted here. A color reproduction method in which three primary color filters of RGB are arranged in the pixels of the LCD to perform juxtaposed additive color mixing is a method generally used in small liquid crystal televisions. In this embodiment, the projected image of this LCD is projected on the lens plate. The lens plate pitch, LCD pixels, and projection optical system are set so that at least one element lens of the lens plate corresponds to one pixel. In the conventional method, a plurality of color parallax images corresponding to the parallax spatially sampled must be accurately matched to the single element of the lens plate, and the display device, the lens plate, and the projection device are required to have extremely high accuracy. .. On the other hand, in the case of the present embodiment, it is only necessary to project the LCD on the screen multiple times, and the alignment accuracy with respect to the lens plate is not required. Further, since the LCD itself has matrix pixels with high positional accuracy, there is an advantage that relative positional accuracy between the projected images can be easily performed. Further, the video signal of the parallax image may be input to the LCD as it is, and it is not necessary to perform the sampling and synthesis to form the display signal. Further, when the projection image of the LCD is made to correspond to the projection pixels of the lens plate by preferably 10 or more element lenses of the lens plate, L
It has an effect of preventing moire fringes between the CD pixel and the lens plate.

Further, an LCD for which multiple projections are made in a screen shape
The arrangement of the images can be changed depending on the application as shown in FIG. For simplification, FIG. 8 shows a case where adjacent projection images for 3 channels are arranged in a horizontal row. For example, as shown in FIG. 8A, when the video signals are sampled by LCD so that the RGB pixels are aligned and multiple projection is performed, even if the viewpoint moves, there is little change in detail color, and it is preferable to use it when importance is attached to color. Further, as shown in FIG. 8B, the sampling of the video signal is shifted so that the RGB pixels are RGB, GR for each adjacent LCD.
By regularly shifting from B and BRG, information of adjacent images having a strong correlation can be mixed and the apparent resolution can be improved as compared with the case of a single LCD. Thus, in this example, a color moving image 3D image could be observed through the lenticular screen. The display space, viewing area, and image size are the same as in the first embodiment. The obtained three-dimensional image was excellent in texture because the image information of a plurality of LCDs was combined and recognized so that color filters and pixels in a matrix were not noticeable.

Although the embodiments have been described above, the present invention is not limited to the above embodiments, but may be a liquid crystal color projector or a CRT.
The projector can be used as a projection display device. In this case, the distance between the display devices becomes larger than the binocular distance, so the conversion optical system of the present invention is very useful.
INDUSTRIAL APPLICABILITY The present invention can obtain a moving image three-dimensional display at a realistic level, and can be widely applied to medical applications, computer graphics, various design work, and the like.

[0041]

As described above, according to the present invention, it is possible to reduce the burden of the number of pixels of one device by performing multiple projection of a plurality of display devices for projection. Further, in the present invention, since the parallax image is automatically aligned with the screen, the projection display image only has to be projected on the lens plate, and there is an advantage that absolute positional accuracy is not required.
Further, since a plurality of pieces of display information are combined and recognized, the matrix-shaped pixels are less noticeable and the texture is excellent. Further, the present invention also has an effect that it is not necessary to spatially sample parallax images and then synthesize the display signals, which is conventionally required. Further, by distributing the light source devices, there is also an effect of reducing the load on the light source. Further, by adopting the conversion optical system according to the present invention,
A continuous three-dimensional field of view can be secured, and the present invention can be used even in a projection display device having a wider space.

As described above, the effect of realizing a three-dimensional moving image and a three-dimensional color moving image without using a holographic method or a very large scale display device is great.

[Brief description of drawings]

FIG. 1 is an explanatory view of the operation of the present invention.

FIG. 2 is a principle diagram of a conventional parallax type three-dimensional display device.

FIG. 3 is a schematic diagram of a three-dimensional display device of the present invention.

FIG. 4 is an elevation view of the three-dimensional display device of the present invention.

FIG. 5 is a diagram illustrating the principle of the conversion optical system (a) and (b).

FIG. 6 is an explanatory diagram when a two-lens system is used for conversion of a phase point surface.

FIG. 7 is a diagram for obtaining a focal length and a lens interval of two lenses.

FIG. 8 is an explanatory view of multiple projection of an LCD image, when RGB pixels are aligned (a) and when RGB pixels are regularly shifted (b).

[Explanation of symbols]

 101 ... Projection display device 102 ... Projection lens 103 ... Lens plate 104 ... Reconstructed image point 105 ... Retroreflective screen 106 ... Illumination light 301 ... LCD 302 ... Lenticular screen 303 ... Convex mirror 304 ... Projection lens 305 ... Fresnel lens 306 ... Halogen lamp 307 ... Forced air cooling device 308 ... Condenser lens 309 ... LCD control / signal processing circuit 310 ... Signal cable

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Okada 3-5-34 Kugayama, Suginami-ku, Tokyo (72) Inventor Hama ▲ Saki ▼ Shoji 1-6-15 Ookayama, Meguro-ku, Tokyo

Claims (6)

[Claims] 1. A three-dimensional display device comprising a plurality of parallax images and a lens plate for selecting the parallax images according to viewpoints, a plurality of display devices for projecting the parallax images, a plurality of projection lenses corresponding to the display devices, a lens plate, and a lens. A three-dimensional display device comprising a retroreflective screen placed on the back focal plane of a plate. 2. The three-dimensional display device according to claim 1, wherein the plurality of display devices for projecting the parallax image are matrix type liquid crystal display devices. 3. The three-dimensional display device according to claim 1, wherein the plurality of display devices for parallax image projection are projection type display devices using liquid crystal. 4. The liquid crystal display device according to claim 1, wherein the plurality of display devices for projecting the parallax image are liquid crystal display devices having an optical arrangement in which projection pixels are superposed on a screen.
Dimensional display device. 5. A three-dimensional display device comprising a plurality of parallax images and a lens plate for selecting the parallax images according to viewpoints, a plurality of display devices for projecting the parallax image, a plurality of projection lenses corresponding to the display device, a lens plate, and a lens. A three-dimensional display device comprising a retroreflective screen placed on the back focal plane of the plate and a conversion optical system for adjusting the projection lens interval in the display space. 6. The three-dimensional display device according to claim 5, wherein the conversion optical system includes a lens element whose optical axis is off.