JP4515565B2 - 3D display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional display device that displays a moving image three-dimensional image that does not require eyeglasses for observation and has little visual fatigue.
[0002]
[Prior art]
Many methods have been proposed and developed for stereoscopic display.
As a general stereoscopic display device, there is a binocular stereoscopic display system as shown in FIG. This is a system that uses two parallax images, a left-eye image 151 and a right-eye image 152, wears polarized glasses or a polarization switching shutter 153, presents each image to each eye, and displays a stereoscopic image. .
This method has a feature that it is possible to easily perform stereoscopic display with a relatively small amount of information. However, when observing the reproduced stereoscopic image 154, visual fatigue due to the difference between the convergence distance 155 and the focus adjustment distance 156 becomes a problem. Yes. This is a problem common to a method of producing a stereoscopic effect only by presenting a parallax image.
[0003]
For displaying a stereoscopic image with little visual fatigue, a method of reproducing a stereoscopic image in space is effective. This method includes a hologram display method and a depth sampling method.
Holograms have the potential for natural 3D display, but they require information on the subject's interference fringes, the amount of information is enormous, and the display device must be very high-definition. There is a problem.
[0004]
On the other hand, in the depth sampling method, a two-dimensional cross-sectional image at each depth position of an object is volumetrically displayed in space. In this method, a three-dimensional image having a depth is reproduced in a three-dimensional space, so that the convergence distance and the focal length match, there is little fatigue, and a natural three-dimensional image that matches the movement of the observation position can be observed. .
This depth sampling method includes a varifocal mirror method that displays images on a vibrating mirror and displays a three-dimensional image, a moving screen method in which the screen moves mechanically at high speed, and a method that uses a rotating spiral screen. . In addition, a method using a liquid crystal display device and having no mechanical drive unit has been developed. For example, there is a method in which a large number of liquid crystal panels are arranged and an image displayed on a CRT is reflected by a panel at an appropriate depth of the stacked liquid crystal panels to display the image volumetrically.
[0005]
FIG. 16 shows an example of a depth sampling method using liquid crystal. The images 163 and 164 for each depth sequentially displayed on the two-dimensional display unit 162 are changed in synchronism with the focal length of the liquid crystal variable focus lens 161 having a diameter of several centimeters or more thereafter, and each image is displayed in space. In this method, the reproduced images 165 and 166 are displayed in a volumetric manner. The feature of this method is that a mechanical drive unit is unnecessary, special glasses are unnecessary, and a natural stereoscopic image can be displayed.
[0006]
[Problems to be solved by the invention]
However, the depth sampling method described above is a time division method in which depth images are sequentially displayed. Therefore, flicker is perceived if the stereoscopic image display is not completed within the afterimage time of the eyes. On the other hand, when the display time of one cross-sectional image is shortened, the luminance of the image is lowered. In addition, a special display device that displays many depth images at high speed within the video rate time is required.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stereoscopic display device capable of preventing a degradation in image quality of depth sampling display due to the above time division and displaying a natural moving image stereoscopic image without visual fatigue using a conventional two-dimensional image display unit. Is intended to provide.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the stereoscopic display device according to the present invention has at least the same number of pixels as the number of pixels of the image of the two-dimensional display unit, and the two-dimensional display unit that displays a moving image and the focal length variable element that can control the focal length. And a focal length control unit that controls the focal length of each focal length variable element constituting the focal length variable element array at high speed based on the depth position information of the subject. And passing incoherent light emitted from each pixel of the image of the two-dimensional display section through the focal length variable element array whose focal length is controlled independently, so that the image of each pixel is in space. It is characterized in that the image is formed at the image point and displayed in three dimensions .
[0008]
Further, the focal length variable element may have a structure in which a refractive index changing medium whose refractive index is changed by an electric field is sandwiched between substrates having transparent electrodes. When a voltage is applied between the electrodes, the refractive index changes. It may have an electrode structure in which the refractive index distribution of the medium becomes the phase distribution of the lens, and when a voltage is applied between the electrodes, the refractive index distribution of the refractive index changing medium becomes the phase distribution of the lens. It may have a substrate shape with a certain curvature, and when a voltage is applied between the electrodes, an electrode having a resistivity distribution such that the refractive index distribution of the refractive index changing medium becomes the phase distribution of the lens. You may have, and it may be comprised from the combination of the thing of the structure which can vary an optical path length with an applied electric field, and a lens.
[0009]
In the stereoscopic display device, before or after the focal length variable element, a lens system that functions to eliminate the distortion of the reproduced image and make the imaging magnification constant may be combined, or the focal length may be combined. It may have an optical system that functions to widen the viewing angle with respect to the output light flux from the variable element array, and each focal length variable element blocks the light in an arbitrary shape to eliminate the phantom effect. You may have the light-shielding part.
Furthermore, the refractive index changing medium may be a medium having an electro-optic effect, and may be a liquid crystal or a mixture containing liquid crystal.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, since the device according to the present invention is a space division method for controlling the image formation position for each pixel, it is possible to prevent flicker and luminance reduction caused by the time division method. It can be used to display natural 3D video images.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0011]
【Example】
(Whole system)
FIG. 1 is a block diagram showing a first embodiment of a stereoscopic display device according to the present invention.
The two-dimensional image display unit 11 of this embodiment is capable of monochrome or color moving image display such as a CRT, a liquid crystal display unit, a plasma display unit, an LED display unit, a projector projection unit, or a laser scanning display unit.
Lights 12a and 12b from the respective pixels of the image of the two-dimensional image display unit 11 enter the focal length variable elements 14a and 14b constituting the focal length variable element array 13 disposed thereafter. Each of the plurality of variable focal length elements constituting the variable focal length element array 13 includes a drive mechanism that can change the focal length independently. The focal length of each variable focal length element is determined based on the depth position information 17 of the subject. As the subject depth position information 17, information obtained by the depth detection unit 16 that can detect the depth distance of the subject can be used.
Further, when the image is not a real image such as computer graphics, depth position information given by calculation can be used.
In accordance with the depth position information 17, the focal length control unit 18 controls the focal length of each focal length variable element. This control is performed at a speed equal to or higher than the video video rate that can handle moving images. The light 12a, 12b from each pixel of the two-dimensional image display unit 11 passes through each focal length variable element 14a, 14b whose focal length is controlled, so that the image of each pixel is an imaging point 15a in space. , 15b, and a three-dimensional image 20 is displayed to the observer 19.
[0012]
(Basic electrode configuration)
FIG. 2 is a cross-sectional view of the focal length variable element of the stereoscopic display device according to the present invention.
A refractive index changing medium 27 is sandwiched between transparent substrates 26 having transparent electrodes 25. The material of the substrate 26 sandwiching the refractive index changing medium 27 is a synthetic resin such as glass or acrylic. The transparent electrode 25 is a thin film such as In ₂ O ₃ : Sn that is adhered to one surface of the substrate 26 by a technique such as vapor deposition.
[0013]
(Special electrode shape)
FIG. 3 shows an electrode structure diagram of the focal length variable element of the stereoscopic display device according to the present invention.
The transparent electrode 31 has a shape such that when a voltage is applied between both transparent electrodes, the refractive index changing medium has an electric field distribution that causes a lens-like refractive index change distribution.
For example, the electrode structure has a circular center and a hole as shown in FIG.
It has a ring-shaped structure as shown in FIG. The electrodes having these shapes are made to face the electrodes attached to the entire surface of the substrate, or these shapes are made to face each other to form a focal length variable element.
[0014]
(Substrate shape)
FIG. 4 is a substrate structure diagram of the focal length variable element of the stereoscopic display device according to the present invention.
A structure in which the substrate has a lens-like curved surface can be used. For example, the single lens substrate 41 in FIG. 4A, the Fresnel lens substrate 42 in FIG. 4B, the grating lens substrate 43 in FIG. 4C, the lenticular lens substrate 44 in FIG. It is.
[0015]
(Resistance distribution)
In addition, a variable focus element having a structure in which a refractive index changing medium is sandwiched between electrodes having different resistance values within the electrode plane, for example, electrodes having different resistance values at the center and the peripheral portion of the electrode can also be used in this stereoscopic display device. .
[0016]
(liquid crystal)
FIG. 5 shows a configuration diagram of a variable focal length liquid crystal lens using liquid crystal or a liquid crystal mixture 51 as a refractive index changing medium of the variable focal length element used in the first embodiment.
As the liquid crystal material, nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, a mixture of these liquid crystals, a composite of liquid crystal and a polymer polymer, or the like is used. Using a liquid crystal with a large difference between ordinary refractive index and extraordinary refractive index (large refractive index anisotropy), a large refractive index change can be obtained even when the liquid crystal layer is thin, and response speed is increased and driving is performed. The voltage can be reduced.
For the liquid crystal that requires alignment processing, a transparent electrode 54 and a transparent electrode 55 are applied on the substrate 52 and the substrate 53, respectively, and an alignment agent is applied to form an alignment film 56, and a rubbing process for controlling the alignment of the liquid crystal is performed. As the alignment method, homogeneous alignment or vertical alignment is used. The distance between the substrates is controlled by the spacer 57, and the liquid crystal or the liquid crystal mixture 51 is injected. The electrode and the substrate shape described above are used.
[0017]
(Liquid crystal lens operating principle, electrode structure)
FIG. 6 shows an example of a focal length variable element using liquid crystal, and the operation principle will be described.
A case will be described in which a circular hole electrode structure 61 as shown in FIG. 6A is provided and a transparent electrode 62 is attached to the entire surface of one substrate. Here, the liquid crystal 63 is shown as a nematic liquid crystal subjected to homogeneous alignment treatment.
FIG. 6B is a diagram when no voltage is applied, and the liquid crystal molecules 64 are aligned in a horizontal direction with both substrates.
FIG. 6C is a diagram when a weak voltage is applied between the electrodes. Since the liquid crystal molecules 64 are aligned in the electric field direction and the electric field is weak at the hole electrode center portion 65, the liquid crystal molecules are aligned in a direction parallel to the substrate, and the hole electrode peripheral portion 66 is inclined in the electric field. It is in an inclined state. This is a convex lens state in which the refractive index at the center is large and the refractive index at the periphery is small.
When a strong voltage is applied between the electrodes, the liquid crystal molecules are aligned in the electric field direction at the hole electrode central portion 65 (FIG. 6D). In the hole electrode peripheral portion 66, the liquid crystal molecules are aligned in the direction of the inclined electric field. In this case, the refractive index of the peripheral portion is larger than that of the central portion, resulting in a concave lens state.
By changing the applied voltage in this way, the refractive index distribution changes and the focal length can be changed.
In addition, when a two-frequency driving liquid crystal whose orientation direction changes depending on the frequency change, the alignment of the liquid crystal can be controlled by changing the driving frequency, and relatively high-speed modulation is possible.
By using such a circular hole shape or ring shape for the electrode structure, it is possible to produce a focal length variable element having a diameter of several tens of μm or less, which can be applied to a stereoscopic display having high-definition minute pixels. Is possible.
[0018]
(Liquid crystal lens operating principle, substrate structure)
FIG. 7 shows another example of the liquid crystal focal length variable liquid crystal lens, and the operation principle will be described.
Here, a case where a substrate having a lens shape is used as the substrate 71 will be described.
A transparent electrode 73 is provided on one side of the lens-shaped substrate 71 to perform an alignment process. At this time, as the alignment treatment, an alignment liquid is applied and the alignment treatment is performed by rubbing with a cloth in a certain direction. When this method is difficult, such as a substrate having a large difference in unevenness, such as a Fresnel lens, a photo-alignment method that irradiates polarized light and controls the alignment is effective. Further, it is possible to provide a function of a variable focal length element even with an alignment process for only one substrate. Further, when it is difficult to deposit a transparent electrode such as a Fresnel lens substrate, a transparent electrode can be attached to the opposite side of the liquid crystal surface of the substrate and driven at a high voltage. As a voltage is applied between the electrodes, the alignment direction of the liquid crystal molecules changes, resulting in a change in refractive index, and the focal length changes. In addition, when a two-frequency driving liquid crystal whose orientation direction changes depending on the frequency change, the alignment of the liquid crystal can be controlled by changing the driving frequency, and relatively high-speed modulation is possible.
Thus, the merit of using a substrate having a curvature is that a large focal length variable element having a diameter of several cm or more can be manufactured. For this reason, it is possible to configure a variable focal length element in which one pixel is large in a large screen size stereoscopic display device.
[0019]
(Configuration of variable focal length element array)
FIG. 8 is a configuration diagram of the focal length variable element array. The focal length variable element array 81 has a shape in which a focal distance variable element 82 is arranged corresponding to each pixel. One focal length variable element is arranged corresponding to one pixel 84 of the two-dimensional display unit 83. In this case, when output light from one pixel is incident on a plurality of variable focus elements, a ghost image is generated and brightness is reduced. Therefore, it is preferable that all the light beams 85 output from the pixels are incident only on the corresponding focal length variable elements. Therefore, a mechanism for limiting the luminous flux from the pixel is required. For example, a fence 86 for preventing the output light from the pixel 84 from entering a focus variable element other than the focal distance variable element 82 is useful.
[0020]
(Optical path length modulation microlens)
FIG. 9 shows another configuration example of the focal length variable element array.
A structure in which a refractive index changing medium 96 is sandwiched between transparent electrodes 95 attached to a substrate 94 and a fixed microlens 99 and microlens 100 are combined. Since the refractive index of the refractive index changing medium 96 changes depending on the voltage applied between the electrodes, the output light from the pixel 92 and the pixel 93 causes an optical path length difference by passing through this cell, and the image to be imaged The position changes and can be used as the variable focal length element array 90.
By placing the refractive index changing medium in the vicinity of the focal points of the microlens 99 and the microlens 100, the positions where the image 98 of the pixel 93 and the image 97 of the pixel 92 are formed can be changed greatly.
Here, liquid crystal, a mixture of liquid crystals, or a material exhibiting a photoelectric effect can be used as the refractive index changing medium.
[0021]
[Example 2]
(Conversion of display device and element array)
FIG. 10 is a configuration diagram of a second embodiment of the stereoscopic display device according to the present invention. As Example 2, an example in which the installation order of the display device and the focal length variable element array is changed is shown.
From the left side of the drawing, parallel light or spread light 103 is input to the focal length variable element array 101, the focal length of each lens is changed according to the depth information, and the output light from the lens is converted into a transmission type two-dimensional. The light is incident on each pixel of the display unit 102, for example, a liquid crystal display unit, and the light intensity and color are modulated and output. Also in this case, an image can be formed on the space for each pixel as in the first embodiment.
[0022]
[Example 3]
(Fourier optics)
FIG. 11 is a block diagram showing a third embodiment of the stereoscopic display device according to the present invention.
The third embodiment includes a first lens system 112 between the two-dimensional display unit 111 and the focal length variable element array 114, and a second lens system 113 between the focal length variable element array 114 and the observer 118. . At this time, the distance between the two-dimensional display unit 111 and the first lens system 112 and the distance between the first lens system 112 and the focal length variable element array 114 are arranged substantially the same as the focal length fl of the first lens system. Further, the focal length variable element array 114 and the second lens system 113 are disposed substantially the same as the focal length f2 of the second lens system.
By taking such an arrangement, distortion associated with the formation of the reproduced image is eliminated. Further, when the image reproduction position is displayed at a position close to the observer 118 and when the image is reproduced at a far position, the image forming magnifications of the reproduced image 117 and the reproduced image 116 can be made the same.
[0023]
[Example 4]
(Expansion of viewing angle)
FIG. 12 is a block diagram showing a fourth embodiment of the stereoscopic display device according to the present invention.
Example 4 is an example in which an optical system 121 is provided between the two-dimensional display unit and the variable focal length array 120 and the observer 128.
The light 122 passing through and outputting the two-dimensional display unit and the variable focal length array expands the viewing angle 123 at the reconstructed image point 126 that connects the images by the optical system 121 to obtain a reconstructed image point 127 having a large viewing angle 124. It has become.
[0024]
[Example 5]
(Resolve the phantom effect)
The phantom phenomenon that occurs when performing stereoscopic display by the depth sampling method will be described with reference to FIG.
Originally, it is behind the object in front of the observer, and the object behind cannot be hidden. However, when depth-sampled stereoscopic display is performed as shown in FIG. 13A and the reproduced image 113 and the reproduced image 134 are observed from the viewpoint 135, the reproduced image 133 in the back can be seen through the reproduced image 134 in the foreground.
[0025]
FIG. 14 is a block diagram showing a fifth embodiment of the stereoscopic display device according to the present invention.
This embodiment is intended to prevent the back image from seeing through the near image due to the phantom phenomenon. The configuration includes a light shielding portion 141 that shields the light 143 from the pixel in an arbitrary shape for each focal length variable element 142 constituting the focal length variable element array. The spreading direction of the output light 146 from the focal length variable element 142 can be controlled by shielding light in an appropriate shape by the light shielding portion. When displaying the reconstructed image point 143, if the light shielding area 147 is set, the reconstructed image point 143 is not observed from the viewpoint 144, and is recognized as being hidden behind the reconstructed image 148 in the foreground. In addition, when the image is moved to the position of the viewpoint 145, the reproduced image point 143 can be observed.
[0026]
(Electro-optic medium)
Although the liquid crystal has been described above as the refractive index variable medium, a focal length variable element using a medium such as PLZT having an electro-optic effect can also be applied to the stereoscopic display device.
The embodiments of the present invention have been described in detail with reference to some examples. However, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the invention defined in the claims. It is obvious that this is possible.
[0027]
【The invention's effect】
According to the present invention, a stereoscopic display device having the following features can be realized.
First, natural stereoscopic vision without visual fatigue that occurs in a conventional stereoscopic display device using parallax images is possible.
Second, special glasses are not required.
Third, stereoscopic viewing in both the horizontal and vertical directions is possible.
Fourth, a two-dimensional display device that has been put into practical use can be used as it is.
Fifth, since stereoscopic display is possible with incoherent light, a color stereoscopic image can be displayed when a color two-dimensional display device is used.
Sixth, since this method performs space sampling and depth sampling, there is no need to sequentially display images at high speed as in time-division display, so that there is no flicker and high-intensity stereoscopic display is possible.
Seventh, stereoscopic observation with a plurality of people is possible.
Eighth, since the information necessary for display in this stereoscopic method is a two-dimensional color image and depth distance information, it is possible to capture a moving image from the subject. In addition, since the amount of information is small, transmission is easy and application to a stereoscopic TV system is possible.
[Brief description of the drawings]
FIG. 1 shows the configuration of a first embodiment of the three-dimensional apparatus of the present invention.
FIG. 2 shows a cross section of the device focal length variable element according to the present invention.
3A and 3B are electrode structure diagrams of the focal length variable element according to the present invention, in which FIG. 3A shows a hole electrode shape, and FIG. 3B shows a ring electrode shape;
4A and 4B are substrate structure diagrams of the focal length variable element of the present invention, in which FIG. 4A is a single lens substrate, FIG. 4B is a Fresnel lens substrate, FIG. 4C is a grating lens substrate, and FIG. 4D is a lenticular lens. Each substrate is shown.
FIG. 5 shows a cross section of a liquid crystal focal length variable element which is an example of the apparatus focal length variable element according to the present invention.
6A and 6B are operation principle diagrams of the liquid crystal focal length variable element shown in FIG. 5, in which FIG. 5A is a diagram of the element structure, FIG. 5B is zero applied voltage, FIG. 5C is a case where the applied voltage is low, and FIG. Each case shows a high voltage.
7A and 7B are operation principle diagrams of another example of the liquid crystal focal length variable element, in which FIG. 7A shows the case where the applied voltage is off, and FIG. 7B shows the case where the applied voltage is on.
FIG. 8 shows a configuration example of an apparatus focal length variable element array according to the present invention.
FIG. 9 shows another configuration example of the focal length variable element array in FIG. 8;
FIG. 10 shows a configuration of a second embodiment of the device of the present invention.
FIG. 11 shows a configuration of a third embodiment of the device of the present invention.
FIG. 12 shows a configuration of a fourth embodiment of the device of the present invention.
FIG. 13 is a diagram for explaining phantom effect cancellation.
FIG. 14 shows a configuration of a fifth embodiment of the device of the present invention.
FIG. 15 is a diagram illustrating a conventional binocular stereoscopic display method.
FIG. 16 is a diagram illustrating a depth sampling stereoscopic display method using a conventional liquid crystal.
[Explanation of symbols]
11, 83, 91, 102, 111 Two-dimensional image display units 13, 81, 90, 101, 114 Focal length variable element arrays 14a, 14b, 132, 142 Focal length variable elements 15a, 15b Imaging point 16 Depth detection unit 17 Depth position information 18 Focal length control unit 19 Observer 20 Stereoscopic images 21, 31, 54, 55, 73, 95 Transparent electrodes 26, 41-44, 52, 53, 67, 68, 71, 72, 94 Substrates 27, 45 , 96 Refractive index change medium 32 No transparent electrode 51 Liquid crystal or liquid crystal mixture 56, 69, 74 Alignment film 57 Spacer 63 Liquid crystal 64, 74 Liquid crystal molecule

Claims (11)

A two-dimensional display for displaying moving images;
A focal length variable element array having a structure in which the focal length variable element capable of controlling the focal length is arranged at least as many as the number of pixels of the image of the two-dimensional display unit, and
A focal length control unit that controls the focal length of each of the focal length variable elements constituting the variable focal length element array at high speed based on the depth position information of the subject ,
The incoherent light emitted from each pixel of the image of the two-dimensional display unit is passed through the variable focal length array whose focal length is controlled independently, and the image of each pixel is connected to an image formation point in space. A stereoscopic display device characterized in that the image is displayed in a stereoscopic manner .   3. The stereoscopic display device according to claim 1, wherein the focal length variable element has a structure in which a refractive index changing medium whose refractive index is changed by an electric field is sandwiched between substrates having transparent electrodes. apparatus.   3. The stereoscopic display device according to claim 2, wherein the focal length variable element has an electrode structure in which a refractive index distribution of the refractive index changing medium becomes a phase distribution of a lens when a voltage is applied between the electrodes. 3D display device.   4. The stereoscopic display device according to claim 2, wherein the variable focal length element has a curvature such that a refractive index distribution of the refractive index changing medium becomes a phase distribution of a lens when a voltage is applied between the electrodes. A stereoscopic display device characterized by having a substrate shape.   5. The stereoscopic display device according to claim 2, wherein the focal length variable element has a resistance such that a refractive index distribution of the refractive index changing medium becomes a phase distribution of a lens when a voltage is applied between the electrodes. A three-dimensional display device comprising an electrode having a rate distribution.   The stereoscopic display device according to claim 1, wherein the focal length variable element is configured by a combination of a lens having a structure capable of changing an optical path length by an applied electric field and a lens.   7. The stereoscopic display device according to claim 1, wherein a lens system that functions to eliminate distortion of a reproduced image and to make an imaging magnification constant before or after the focal length variable element is combined. 3D display device.   8. The stereoscopic display device according to claim 1, further comprising an optical system having a function of widening a viewing angle with respect to an output light beam from the focal length variable element array. 9.   9. The stereoscopic display device according to claim 1, wherein each of the focal length variable elements includes a light-shielding portion for shielding light in an arbitrary shape to eliminate the phantom effect.   10. The stereoscopic display device according to claim 1, wherein the refractive index changing medium is a medium having an electro-optic effect.   11. The stereoscopic display device according to claim 1, wherein the refractive index changing medium is a liquid crystal or a mixture containing liquid crystal.

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