JP4002218B2 - Stereoscopic image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stereoscopic image display device.
[0002]
[Prior art]
There is known a method of recording a stereoscopic image by some method and reproducing it as a stereoscopic image, which is called an integral photography method (hereinafter also referred to as IP method) or a light ray reproduction method for displaying a large number of parallax images. As shown in FIG. 24, when a person sees an object from the left and right eyes 32 and 33, the angle formed with the left and right eyes when viewing the object 34 at the close distance A is α and the distant distance B is the point. If the angle between the left and right eyes when viewing the object 35 is β, the angles α and β vary depending on the positional relationship between the object and the observer. This (α-β) is called binocular parallax, and a person can be stereoscopically sensitive to this binocular parallax.
[0003]
In recent years, three-dimensional displays without glasses have been developed. Many of these use ordinary two-dimensional (hereinafter also referred to as 2D) displays. This display uses the binocular parallax described above, and when a light beam control element is placed on the front or back of the display and viewed from an observer, it is placed at a distance of several centimeters from the display. The light beam control element controls the angle of the light beam from the display so that the light beam is emitted from the object. This enables stereoscopic viewing. This is because, due to the high definition of the display, it has become possible to obtain a high-definition image to some extent even if the light rays of the display are distributed to several angles (referred to as parallax).
[0004]
FIG. 25 shows a schematic configuration diagram of a display in a case where parallax is given in the horizontal direction among stereoscopic displays without glasses. FIG. 25 is a schematic view of the relationship between the display surface 1, the observer 4, and the light beam control element 8 as viewed from above. In FIG. 25, a large number of image information viewed from a certain observation direction is displayed on the display surface 1 of the two-dimensional image display device, and light control elements 8 (for example, slits, pinholes, micros) provided on the front surface of the display surface are displayed. A three-dimensional image corresponding to the observation direction is displayed when the observer 4 observes the image through a lens or a lenticular lens, for example, an array plate having an opening 2 and a blocking part 3. is there. In FIG. 25, the observer at the position of α can see the image with the parallax number p3, and the observer at the position of β can see the image with the parallax number p2, and is similarly at the position of γ. The observer can see the image with the parallax number p1. Since the IP method can perform multi-parallax display, it can display motion parallax in which an image corresponding to the position can be viewed even when the observer moves, so that natural stereoscopic viewing is possible. In addition, since the light beam for reproducing the stereoscopic image follows the same path as when the actual object is actually arranged, it is excellent in that the problem of the visual field conflict does not occur.
[0005]
By the way, as a method of creating a parallax image and displaying the parallax image as pixel information through the opening, a method of performing image mapping by generating light rays for reproducing a stereoscopic image from the pixel side, and an observer There are two types of methods for performing image mapping by tracing light rays backward from the viewpoint position toward the pixel. Here, the method of performing image mapping using the former method is referred to as an IP method, and the latter method is referred to as a multi-parallax stereoscope and a parallax barrier method.
[0006]
The light beam of the IP method is not directed toward the observer's eyes, but is emitted from all openings at almost equal intervals toward the observer's direction by the number of parallaxes. For this reason, the amount of constituent pixels at a certain angle is smaller than that of the original two-dimensional display, and the light beam is emitted toward the position of the observer's eyes because of the excellent motion parallax when the observer moves. The resolution is lower than the display. Thus, attempts have been made to increase the resolution.
[0007]
For example, an image display device is known that performs pixel shift by switching optical paths at high speed without using a vibration or rotation mechanism to multiply the apparent pixels (see, for example, Patent Document 1). In this apparatus, an optical path deflecting means using a Bragg diffraction element having a polymer-dispersed liquid crystal structure is arranged immediately in front of the screen to shift the image light by an arbitrary distance in the pixel arrangement direction. The shift amount is set to 1 / integer of the pixel pitch. When performing image multiplication twice as much as the pixel arrangement direction, the pixel pitch is set to ½. By correcting the image signal for driving the liquid crystal panel according to the shift amount by the shift amount, an apparently high-definition image can be displayed. In the above apparatus, there is a problem that the optical path deflecting means is required, so that the apparatus becomes large.
[0008]
On the other hand, there are also examples in which the viewing angle of a 3D (three-dimensional) display is increased by bending the display or surrounding an observer. For example, an apparatus is known in which an image sheet formed from image data having a parallax of 10 ° or more is attached to a cylindrical display surface (see, for example, Patent Document 2). This provides a variable image to the observer over a wide area. The above device is a display created for enlarging the viewing zone, and does not take measures to improve the resolution.
[0009]
In addition, display devices such as liquid crystal displays look good from the front, but when viewed from an angle, the viewing angle may be narrowed due to the direction of rising of liquid crystal molecules, etc. ing. For example, a VA liquid crystal display device is known in which the contrast, operation speed, and the like remain good as in the past and the viewing angle characteristics are also good (see, for example, Patent Document 3). In this liquid crystal display device, a liquid crystal having negative dielectric anisotropy is sandwiched between first and second substrates subjected to vertical alignment treatment on the substrate surface, and the alignment of the liquid crystal is almost vertical when no voltage is applied. The first and second substrates are configured to be substantially horizontal when a predetermined voltage is applied, and to be inclined when a voltage smaller than the predetermined voltage is applied. The first and second substrates regulate the liquid crystal alignment direction on the first and second substrates. The first and second domain regulating means have a configuration in which a plurality of protrusions, depressions or slits bent zigzag in a predetermined cycle are arranged in parallel at a predetermined pitch. In the liquid crystal display device, the tilt angle of the liquid crystal molecules is inclined, but the viewing angle characteristics are improved by directing the rising direction of the liquid crystal molecules in different directions within a narrow range, and the resolution is not improved.
[0010]
Further, the three-dimensional display device includes a flat panel display on which a plurality of parallax images are simultaneously displayed and an array of cylindrical lenses having the same shape, and a lenticular lens mounted on the surface of the flat panel display. In addition, a three-dimensional display device is known in which the flat panel display and the lenticular lens are curved with the same center of curvature (see, for example, Patent Document 4). This apparatus has a simple structure, suppresses the generation of sidelobe light, and enables normal stereoscopic viewing without viewing an abnormal stereoscopic image. In the display device, it is desirable that the direction in which light is emitted by the light control element is focused toward the observer.
[0011]
There is known a display device that enables stereoscopic viewing using binocular parallax without wearing special glasses, and at the same time allows a plurality of viewers to observe an image (for example, see Patent Document 5). This display device combines a directional reflection screen having a group of mirrors as a horizontal condensing unit and a stereoscopic image projection unit with respect to an observer, and at least part of the included angle of the group of mirrors is non-perpendicular. The directional reflection screen S is used. Therefore, the above-mentioned screen broadens the viewing zone by distributing the image on the screen according to the position of the observer by specular reflection, and no measures are taken to improve the resolution.
[0012]
In the IP method, when a solid is reproduced at a position away from the display surface, there is a problem that the resolution rapidly decreases due to the spread of the light bundle assigned through the aperture or the lens (for example, Non-patent document 1).
[0013]
[Patent Document 1]
JP 2002-156617 A
[Patent Document 2]
JP-A-11-109287
[Patent Document 3]
Japanese Patent Laid-Open No. 11-16335
[Patent Document 4]
JP-A-6-289320
[Patent Document 5]
Japanese Patent Laid-Open No. 9-189884
[Non-Patent Document 1]
H. Hoshino, F. Okano, H. Isono and I. Yuyama "Analysis of resolution limitation of integral photography", J. Opt. Soc. Am, A15 (1998) 2059-2065.
[0014]
[Problems to be solved by the invention]
In the IP method, when a solid is reproduced at a position distant from the display surface, a problem that the resolution rapidly decreases will be described below.
[0015]
Β (cycle per radian: cpr) is used as a scale representing the resolution of a stereoscopic display. β is an index of how many cycles of light and darkness can be displayed per radius. As shown in Non-Patent Document 1, in the IP method, the resolution β in the stereoscopic image near the display_nyqIs called the Nyquist frequency, and is determined by the distance from the observer 4 to the opening 2 and the pitch of the opening 2 (see FIG. 26). P is the pitch of openings 2_e, Where L is the distance from the observer to the aperture or lens, the pitch p of the aperture 2_eResolution β limited by_nyqIs
β_nyq = L / (2p_e (1)
It becomes.
[0016]
Next, as shown in FIG. 27, the position away from the display surface, that is, from the observer 4 to z_iIf the object 13 is reproduced at a distant position, the resolution is drastically lowered due to the spread of the light beam assigned through the opening 2 or the lens. In FIG. 27, β is the resolution determined by the pitch of the aperture or the lens pitch, and α indicates the resolution determined by the density of light rays emitted from one aperture or lens, that is, the pixel pitch and the number of parallaxes. When the object 13 is reproduced in a region (front region) protruding from the display 1 or a depth region (region located on the rear surface), it is calculated from a group of light rays emitted from one slit in order to reproduce the image. Α is the maximum resolution_imaxThe spatial frequency β of the object viewed from the observation point_imaxIs
β_imax = Α_imax Xz_i/ | Lz_i| (2)
It becomes.
[0017]
In addition, in order to prevent the image from being broken due to the diffraction of the light beam at the slit, the first frequency at which the MTF (modulation transfer function) of the opening 2 becomes 0 is expressed as α._cThe alpha_cWidth w of the opening when maximizing_opt, The maximum value α of the viewing zone angle at the opening_imaxCan be decided. When the distance between the slit 8 and the display surface 1 is g, and the wavelength of the light beam 7 is λ, the optimum opening width w_opt, The optimal α_imaxIs as follows from Patent Document 1.
α_imax= (G / λ)^1/2       (3)
w_opt= 2 (g × λ)^1/2      (4)
Then, equation (2) becomes
βcopt = (g / λ)^1/2 z_i/ | Lz_i| (5)
It becomes. Actual resolution_imaxIs the above β_nyqAnd β_imaxBecause it becomes the lower one when comparing
Β_imax= Min (β_imax, β_nyq (6)
It is expressed.
[0018]
Here, the pitch p of the opening from the equation (1)_eIt can be seen that the resolution of the three-dimensional image increases as the value of becomes smaller, that is, as the definition of the display surface becomes higher. However, narrowing the pixel pitch of the display surface itself has a problem that it cannot be easily realized due to process changes and the like.
[0019]
If the object image 13 is in the vicinity of the display surface 1, β_nyqIs β_imaxIt is dominant because it becomes smaller. Further, as the object image 13 is further away from the display surface 1, z in equation (5) is obtained._iBecomes smaller, β_imax Resolution is dominant. From equation (5), by increasing the distance g between the slit 8 and the display surface 1, β_imaxIt turns out that becomes large.
[0020]
FIG. 28 shows a schematic view of the two-dimensional flat display 1 and the plane 8 or lens array having the opening 2 as viewed from above. A region where normal parallax can be seen from both the left end and the right end of the screen is referred to as a viewing zone 5 and is indicated by hatching in FIG. The area other than the shaded area in FIG. 28 is called a false image, and a display surface other than the light beam originally intended is seen through the slit. In FIG. 28, when the viewing distance is determined, the correct light flux can be seen in all regions farther away from the display surface.
[0021]
By narrowing the viewing zone, that is, by increasing the distance g between the slit 8 and the display surface 1, β_imaxFIG. 29 shows a schematic diagram of the light flux and the viewing area (shaded portion) viewed from the upper side of the display 1 when the resolution is increased and the resolution is increased. As can be seen from FIG. 29, when the viewing area 5 is narrowed, there is a problem that the viewing area 5 narrows in a direction away from the screen with respect to the observer 4.
[0022]
The present invention has been made in view of the above circumstances, and even when a three-dimensional image is reproduced at a position away from the display surface, the resolution is not lowered and the image is viewed in a direction away from the screen on the basis of the observer. An object of the present invention is to provide a stereoscopic image display device capable of preventing the area from becoming narrow.
[0023]
[Means for Solving the Problems]
The stereoscopic image display apparatus according to the first aspect of the present invention includes a display unit in which pixels positioned in a concave or convex display surface viewed from the observer are arranged in a matrix, and a two-dimensional pattern. The display device includes a two-dimensional pattern display means for displaying on the display surface of the display unit, and a light beam control unit that has a plurality of apertures or a plurality of lenses and controls light beams from the pixels.
[0024]
In addition, you may comprise the said display part so that it may be provided with the at least 2 planar display surface connected seamlessly.
[0025]
The display surface of the display unit may be a curved surface.
[0026]
It should be noted that the position where the perpendicular line drawn down on the display surface intersects the display surface and the position of the center of the parallax image from the center of the opening or the lens of the light beam control unit is shifted according to the tilt angle of the display surface. Good.
[0027]
In addition, it is preferable that the amount of deviation between the opening of the light beam control unit or the center of the lens and the parallax image group differs between the end portion and the central portion of the display unit.
[0028]
In addition, it is preferable that the parallax image group at the end of the display unit is shifted in the direction of the end of the display unit with respect to the center of the opening.
[0029]
When the display unit is a liquid crystal display device, an inclination angle formed between a tangent of an arbitrary point on the display surface of the display unit and a plane parallel to the viewing distance plane is θ._Y, The angle formed by a line connecting an arbitrary opening and the center of the viewing distance plane and a line connecting the opening and the viewing distance plane with the shortest distance is θ_ZThen, the maximum tilt angle θ of the liquid crystal molecules_MBut
θ_M= Θ_Y−θ_Z
It is preferable that it is comprised so that.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0031]
(First embodiment)
A configuration of a stereoscopic image display apparatus according to the first embodiment of the present invention is shown in FIG. FIG. 1 is a horizontal sectional view of the stereoscopic image display apparatus according to the present embodiment cut along a horizontal plane as viewed from the observer. The stereoscopic image display apparatus according to this embodiment includes a display unit (display) 1 in which two planar display surfaces are formed in a concave shape toward the observer 4, and light control placed on the front surface of the display unit 1. A unit 8 and a two-dimensional pattern display means (not shown) for displaying the two-dimensional pattern on the display unit are provided. The display unit 1 has a configuration in which two flat display surfaces are seamlessly connected. Pixels are arranged in a matrix on each planar display surface. The two display surfaces are each at an angle θ with respect to the vertical surface 100 viewed from the observer 4._YJust leaning. Similar to the display unit 1, the light beam control unit 8 has two planar light beam control elements formed in a concave shape toward the observer 4, and these two planar light beam control elements are connected to the observer 4. Each angle θ with respect to the vertical plane 100_YJust leaning. Each light beam control element has a plurality of openings or a plurality of lenses formed in an array. In the present embodiment, the light beam control unit 8 is provided on the front surface of the display 1 when viewed from the observer 4, but may be provided on the back surface.
[0032]
A point P on a line 19 extending in a direction perpendicular to the vertical plane 100 from the junction of the two display surfaces of the display unit 1_AAssume that the observer 4 is located at That is, this position P_AThe distance L from the center to the center of the light beam control unit 8 is the viewing distance. The line 19 is a line drawn from this position toward the center of the display 1 when the observer 4 stands at a position where the display 1 can be viewed symmetrically.
[0033]
If the viewing zone angle at the central opening of the light beam controller 8 is 2θ, the viewing zone angle at the openings at both ends 8a and 8b of the light beam controller 8 is also 2θ. And the opening part of the both ends 8a and 8b of the light beam control part 8, and the point P_AThe distance 11 between the points where the rays 7a and 7b forming an angle θ outward from the respective lines connecting the two and the viewing distance plane 102 where the observer 4 is located parallel to the vertical plane 100 is the viewing distance L. This is an area where no false image can be seen.
[0034]
Next, the principle of resolution improvement of this embodiment will be described. First, the principle of improving the resolution by the fact that the horizontal size of the pixels is apparently reduced due to the tilt of the display surface will be described with reference to FIGS.
[0035]
2A and 2B are views of the display 1 and the light beam control unit 8 having the opening 2 and the light shielding unit 3 as seen from above. When the pixel 14 is viewed from the front through the opening as shown in FIG. 2A and the angle θ from the front as shown in FIG._YThe sizes of the pixels 14 are compared when they are tilted and viewed obliquely through the opening. In general, in the creation of a stereoscopic image by the IP method, the pitch of an aperture or lens is pixel pitch × number of parallaxes. Therefore, since the apparent lens pitch is reduced by viewing from an oblique direction, the pitch p of the openings 2 in the equation (1)_eCan be reduced, and βnyq increases. Next, since the pixel pitch is apparently reduced, the light density from one opening is increased, and βimax in the equation (5) is increased. The actual pixel size is w_pThen, the pixel pitch of the apparent pixel seen from the diagonal is w_p× cosθ_YThus, the pixel 14 is smaller than when viewed from the front through the opening.
[0036]
Next, a pixel array arranged through the opening 2 of the light beam control unit 8 will be described. First, in FIG. 3, the light beams of the parallax image group 21 emitted from each opening when the stereoscopic image display device according to the present embodiment including the display 1 and the light beam control unit 8 having the opening 2 is viewed from above. Show the trajectory. In FIG. 3, a case of 8 parallax will be described as an example. In the center of the display 1, the parallax images constituting the parallax image group 21 emitted from the respective openings 2 are assigned symmetrically. That is, the parallax images are assigned so that the parallax numbers are −4, −3, −2, −1, 1, 2, 3, and 4. Each parallax number corresponds to one parallax image. At this time, the parallax is a value determined by an absolute angle emitted from the display 1 in the viewing distance direction regardless of the position of the observer, and this time, the shortest distance from the central portion of the display 1 in the viewing distance direction. With reference to the line 19 drawn in step 1, the angle is determined by how many times the line 19 is deviated therefrom. For example, the parallax (parallax angle) α of the parallax image with parallax number k is 2θ and the number of parallaxes is n (8 in FIG. 3).
α = θ · (2k−1) / n (k> 0)
α = θ · (2k + 1) / n (k <0)
It is expressed. When the parallax number n is an odd number,
α = 2θ · k / n
It is expressed. The parallax angle α is positive in the clockwise direction.
[0037]
The number of parallaxes n can be freely determined, but may be determined by specifications such as the definition on the display surface, the amount of pop-out that does not fall below a certain threshold, and the range of depth. At the right end 17 of the display 1, it is assumed that the position of the observer 4 is often in the center of the display 1, so that the light emitted from the opening at the right end of the display 1 faces the center of the display 1. A parallax image group with parallax numbers 1, 2, 3, 4, 5, 6, 7, and 8 may be emitted. Further, at the left end 18 of the display 1, the parallax images with the parallax numbers −8, −7, −6, −5, −4, −3, −2, and −1 may be emitted symmetrically with the right end 17.
[0038]
Next, the relationship between the parallax image and the slit opening when the observer sees the vicinity of the center of the display will be described with reference to FIG. FIG. 4 is a view of the display 1, the opening 2, and the light rays of the display image at the center of the parallax image group as viewed from above. Here, the shortest distance between the display 1 and the light beam control unit 8 is d, and the tilt angle of the display 1 is θ._YThen, the point P where the observer 4 is located from the center of the parallax image group 21_AIn order for the light rays to be emitted at the shortest distance toward the center, the center of the parallax image group 21 is positioned at the position P of the display 1 immediately below the opening 2._DFrom
t = d × tan (θ_Y(7)
It is necessary to bring it closer to the center of the display 1 only. Width w of opening 2_optAlthough it is better to determine as in the equation (4), it is determined to be the same size as the normal pixel size so that the light beam at the center of the parallax pixel is emitted most effectively. The spread 23 of the parallax image group on the viewing distance plane 102 is as shown in FIG.
[0039]
Next, FIG. 5 shows a view of the relationship between the parallax image at the left end of the display 1 and the opening from above. As shown in FIG. 3, by selecting the parallax number from -8 to -1 at the left end 18 of the display 1, the light beam 7 emitted from the opening is brought to the center, and thereby a normal parallax image can be seen. The possible area becomes wider. Therefore, the center P of the parallax image group 21 seen through the opening at the left end of the display 1 and the extension line of the light ray connecting the opening 2 is a point P where the observer 4 is located._ATo reach the shortest distance. Projection point P of display 2 on display 1_DAnd the disparity amount t between the center of the parallax image group 21 on the display, the distance between the display 1 and the light beam control unit 8 is d, and the tilt angle of the display 1 is θ_YWhen the observer 4 stands at a position where the display 1 can be viewed symmetrically, a line 19 drawn from this position toward the center of the display 1 and a position P where the observer 4 is present_AThe angle formed by the straight line from the head toward the opening 2 is θ_ZThen,
t = d × tan (θ_Y−θ_Z (8)
It becomes. As described above, the shift amount at the center of the display 1 is expressed by the equation (7), and the shift amount at the end portion is expressed by the equation (8). For this reason, it is necessary to make the opening pitches different between the central portion and the end portion of the display 1, and the versatility of the light beam control element having the opening portion or the lens array is lost.
[0040]
Therefore, in the present embodiment, by changing the position of the parallax image to be displayed, the parallax image can be emitted at a normal position even if the opening pitch is constant. That is, with respect to the shift amount t between the center portion and the opening portion of the parallax image group 21 at the display end, the display center is also displayed by shifting the parallax image group toward the display end in a position where the shift amount is the same as the center portion. The ends also have the same opening pitch or lens pitch. FIG. 6 shows the positional relationship between the respective openings at the center and the end of the display 1 and the parallax image group. FIG. 6A shows a case where the amount of deviation between the center of the display 1 and the center of the parallax image group of the opening at the end is changed depending on the location, that is, the amount of deviation is a value defined by the equation (8). 6 (b) shows a case where the shift amount between the center portion and the end portion of the display 1 is not changed depending on the location, that is, the shift amount is a value defined by the equation (7). In FIG. 6A, the pitch of the openings 2 is changed between the central part and the end part of the light beam control unit 8, but in FIG. 6B, the central part and the end part of the light beam control unit 8 are changed. The pitch of the openings 2 is constant. A broken line 60 in FIG. 6B is a line corresponding to the outermost light beam 60 emitted from the opening 2 at the end of the light beam control unit 8 illustrated in FIG. Therefore, as shown in FIG. 6B, at the display end, by creating a parallax image closer to the display end with respect to the opening, the opening pitch can be made constant at the center and the end of the display. . Thus, even if a plane having an opening in a normal display having no inclination or a light beam control element similar to the lens array is used, the amount of deviation from the display image is expressed by the following equation (7): A stereoscopic image display device with high resolution and high presence can be obtained.
[0041]
FIG. 7 shows how to assign parallax numbers on the display in accordance with the angle emitted from the display 1 when the shift of the parallax image group in FIG. 6 is taken into account. The angle formed by the line 19 connecting the observer 4 located at the center of the viewing distance and the center of the display 1 and the line 62 connecting the arbitrary opening of the light beam controller 8 and the observer 4 is θ_ZAnd the angle of one parallax is θ_NIf
θ_N= Viewing angle / number of parallax = 2θ / number of parallax
It becomes. θ_ZIs the angle θ of one parallax image_NIf it becomes larger, the parallax numbers should be shifted one by one. When the parallax image is shifted, pixels that do not belong to any parallax number are generated at the boundary of the shifted parallax image. In this case, it is difficult to recognize the transition of the image at the boundary by placing some parallax image.
[0042]
For example, an embodiment will be described for a case where a stereoscopic image is created with 8 parallaxes. In FIG. 7, θ in the A, B, C, and D regions for the case of 8 parallaxes._ZAnd θ_NAssume that the relationship is as follows. As left-right symmetry, only the left half will be described.
A; 0 ≦ | θ_Z| <Θ_N/ 2
B; θ_N / 2 ≦ | θ_Z｜ <3θ_N / 2
C; 3θ_N / 2 ≦ | θ_Z｜ <5θ_N / 2
D; 5θ_N / 2 ≦ | θ_Z｜ <7θ_N / 2
E; 7θ_N / 2 ≦ | θ_Z｜
Then,
In area A, from -4 parallax to 4 parallax
In region B, from -5 parallax to 3 parallax
In region C, from -6 parallax to 2 parallax
In D region, from -7 parallax to 1 parallax
In E region, from -8 parallax to -1 parallax
It is good to sort like
[0043]
As described above, the case of the stereoscopic image display device provided with the tilted display 1 and the light beam control unit 8 having the linear opening 2 on the plane has been described. Even if the part is replaced with a flat opening and the lens width is replaced with the opening pitch, a good three-dimensional display in which the luminance does not decrease can be obtained.
[0044]
In addition, the tilted display allows two liquid crystal modules to be_YBy simply tilting, it can be obtained with an existing display, and the slit design can be obtained simply by shifting the existing one.
[0045]
In the present embodiment, a display that is tilted seamlessly has been described. However, in a state where two normal flat displays are combined, an area where no light beam is emitted is generated due to the influence of the frame of the display, and the image becomes discontinuous. Therefore, as shown in FIG. 8A, a mirror 40 with a sparse surface is placed on the frame, and an image that does not contribute to the light control of the display 1 near the mirror 40 may not have a background or parallax. Is displayed, and it is ejected in all directions, so that the lack of an image at the discontinuous portion becomes inconspicuous. FIG. 8B is an enlarged view of the joint portion 41 between the display 1 and the mirror 40.
[0046]
Further, as a first modification of the stereoscopic image display device according to the present embodiment, as shown in FIG. 9, the display unit 1 includes a display unit including two planar display surfaces used in the present embodiment. A plurality of them may be combined. In this case, the light beam control unit 8 has the same shape as shown in FIG.
[0047]
Further, it is conceivable to use a concave curved surface display as a method for making the joint inconspicuous. An example using a concave curved surface display will be described with reference to FIG. 10 as a second modification of the present embodiment. As shown in FIG. 10, by making the display 1 into a concave curved surface, a high-resolution display without a seam can be obtained. In this case, the concave curved surface display 1 and the light beam control unit 8 have the same radius of curvature R. When a concave curved display is used, since the display is not inclined at the center of the display 1, the resolution is the same as that of a normal flat display. However, since the edge of the display 1 is inclined, the apparent pixel pitch is small. And the resolution increases. When the display is enlarged, the edge of the image is often far from the observer. In this case, if a concave curved surface display is used, the resolution at the display end can be increased.
[0048]
Further, by using a concave curved surface display or an inclined display, the image edge comes out forward, so that a three-dimensional image with a large pop-up amount can be displayed compared to a conventional flat display.
[0049]
In general, the resolution is determined by the distance between the plane having the aperture or the position of the lens array and the image. Therefore, the concept of the resolution limit in the pop-out amount direction in the flat display and the concave curved display will be described with reference to FIG. 11A is a horizontal sectional view when a concave display is used, and FIG. 11B is a horizontal sectional view when a flat display is used. In FIG. 11A, reference numeral 64 is a curved surface having the same curvature as that of the concave curved surface display 1, and reference numeral 42 is a line calculated that the resolution is constant.
[0050]
L is the shortest distance between the viewing distance plane 102 and the image edge._A, The shortest distance between the viewing distance plane 102 and the center of the display is L_BThen, even if the resolution is the same, when using a concave curved surface display, on average L_B-L_AThe pop-up amount determined from the resolution limit can be increased. However, the average depth is L_B-L_AOnly the depth is determined from the resolution. Independent of the effect that the image edge appears in front, an increase in resolution (an amount corresponding to the reference numeral 26 in FIG. 11) occurs because the display described above is slanted. , Display with a large resolution.
[0051]
When the concave curved surface display shown in FIG. 10 is used, the distance L between the edge of the display 1 and the viewing distance plane 102._A= 1.11 m, distance L between display center and viewing distance plane 102_B= 1.15 m, viewing zone angle 2θ = 18 °, radius of curvature R of concave curved surface display 1 = 0.45 m, gap between light beam control unit 8 and display 1 is g = 2.5 mm, and concave curved surface display 1 is Angle 2θ stretched with respect to the center of curvature of the display area when viewed from above_MHalf of θ_M= 24.5 ° The resolution is calculated. Nyquist frequency β calculated by the equation (1) at the edge and the center of the display 1 as seen from the center of the viewing distance plane._nyqAnd the resolution β of the stereoscopic image when the aperture is optimized, calculated by the equation (5)_coptThe calculation results are shown in FIG. Note that the horizontal axis z in FIG. 12 indicates the distance from the viewing distance plane 102 to the stereoscopic display image, as shown in FIG.
[0052]
From FIG. 12, by making the display 1 into a concave curved surface, for example, an area where 600 cpr can be realized approaches the observer up to z = 1.05 m at the center of the display 1 and z = 1 m in the light rays from the edge of the display 1. be able to. In other words, the distance from the opening at the center of the display 1 to the display limit is 10 cm (= 1.15 m−1.05 m). The distance from the opening at the end of the display 1 to the display limit is 11 cm (= 1.11 m-1 m). This 1 cm is an improvement in resolution due to apparent pixel size reduction caused by tilting the display 1. By further tilting the display 1, the resolution is further increased. Further, the improvement of the display limit of 5 cm is considerably difficult to realize by changing the process for reducing the pixel size. For this reason, the resolution improvement by the concave curved surface display is effective.
[0053]
Next, FIG. 13 shows a case where a conventional flat display is used when viewing the display edge from an observer at the center of the viewing distance seen symmetrically of the display, and a case of this embodiment using a concave curved surface display. Indicates the resolution. Note that the size of the curved display 1 of the present embodiment is the size of the curved display used in the calculation of FIG. Also, the horizontal axis z in FIG. 12 indicates the distance from the viewing distance plane 102 to the image, as shown in FIG.
[0054]
From FIG. 13, when the image is formed between the display 1 and the observer, that is, in the protruding region of the display 1 (z ≦ 1.15), the resolution of the present embodiment is higher than that of the conventional case. ing.
[0055]
As described above, in the concave curved display, the display edge has a certain range of resolution because the resolution is improved by reducing the apparent pixel pitch from the center of the display and the screen coming forward. It will be. From FIG. 13, it can be seen that the present embodiment using the concave curved surface display improves the resolution with respect to the pop-out amount, compared with the conventional case using the flat display.
[0056]
In designing a 3D display, the changes when a flat display is changed to a concave curved display will be described. First, the display must be curved.
[0057]
The design of slits and lens arrays, which are light beam control elements on curved displays, is the same as curved displays, even if the distance between the concave curved display and the light control element is constant or changed depending on the location. It is necessary to have a curved surface. Otherwise, the pixels on the display surface are not emitted in the proper direction, and image degradation such as crosstalk and double images occurs. With respect to the opening such as a slit or the pitch of the center of the lens array, the tilt angle differs from place to place, unlike the tilted display. Therefore, the distance between the display and the light beam control element is d, and an arbitrary position P on the concave curved surface display 1 from the center of the concave curved surface display 1 as shown in FIG._xIf the distance to x is x, the position P where the observer 4 is_AThe position P from the center of the display 1 when viewed from the top_xAngle θ_ZX / L, and the angle θx of the arc when viewed from the center of curvature of the display 1 can be expressed as x / R._xThe amount of deviation of the opening at the center of the image is modified from equation (8),
t = d × tan (θx−θz)
= D x tan (x / Rx / L) (9)
It becomes. In addition, as described in the tilted display, an area called a viewing zone that prevents a false image that does not pass through the light control element that should pass originally from appearing by bringing the parallax emitted from the edge of the display to the center. In order to make it wider, the parallax number is gradually changed as it goes to the edge of the screen. It is also desirable if the opening pitch can be kept unchanged even when the curvature angle or radius of curvature of the concave curved display is changed.
[0058]
In the case of the tilted display, as shown in FIG. 7, it has been described that the parallax number is changed to face inward as the display goes to the end. In this case, the tilt angle of the display is θ_YTherefore, the angle θ for causing the central ray of the parallax number to be emitted from the opening at the center of the viewing distance plane_ZIs a function of only the parallax display position z. However, as shown in the equation (7), in the case of a concave curved surface display, the inclination angle θ_YIs also a function of the display position x. For this reason, if the opening pitch is made constant, it is designed to be emitted from two types of openings adjacent to one parallax number under the following conditions, and thus crosstalk occurs. In that case, the aperture pitch is changed as a function of x depending on the location, or in the boundary region where the parallax number to be emitted changes in advance, either the parallax number that causes crosstalk is deleted, or the dominant parallax number It is necessary to take measures such as selecting.
[0059]
For example, with reference to FIG. 14, the conditions for preventing crosstalk will be described. FIG. 14 shows the case of 8 parallaxes. The parallax number on the display 1 and the light beams of the respective parallax numbers that spread through the opening will be described. First, the parallax number assignment method and the relationship between the curvature angle and the viewing zone angle at the boundary 39 of the region displaying from -4 parallax to 4 parallax to the region displaying from -5 parallax to 3 parallax will be described.
[0060]
The curvature angle is determined by a distance x from the center on the display 1 and is expressed as x / R and is a function of x. The angle per one parallax image where N is the number of parallaxes is θ_NAnd the curvature angle of the concave curved surface display 1 is θ_MThen, if the parallax numbers are assigned as shown in FIG. 7, the boundary is as shown in FIG.
[0061]
When the parallax number is switched at the above boundary, as a condition that the parallax number between adjacent openings is not overlapped and mapped to the same pixel,
θ_x−θ_Z> 0
That is, from FIG.
θ_N/ 2−θ_M/ Number of parallax> 0 (10)
It is. When the above conditions are satisfied, a parallax number without crosstalk can be assigned. For example, the larger the number of parallaxes, the easier it is to satisfy the above conditions. In the case of a flat display or a tilted display, pixels that do not belong to either parallax are generated at the boundary where the parallax number assignment is changed, but in the case of a concave curved display, such pixels may not be generated. it can.
[0062]
Further, the alignment of the light beam control element and the display 1 is also important. If the light beam control element and the display 1 are manufactured integrally, the alignment is easy. However, if the light control element and the display 1 are attached later, it is preferable to facilitate the alignment image. The position of the light beam control element may be behind or in front of the display 1. Moreover, you may project on a curved screen like a projector system.
[0063]
Although the shape of the curved display is shown in FIG. 10 as a part of an arc having a radius of curvature and a curvature angle, the display 1 using a part of an ellipse may be used as shown in FIG. Little change in tilt angle. In FIG. 16, when the two focal points of the ellipse are F and F ′, the locus P of the ellipse is
FP + F'P = constant
It becomes. Therefore, assuming that the line connecting the focal points F and F ′ of the ellipse is the optimal viewing distance and the two focal points are the respective ends of the parallax image, the parallax images at both ends of the center of the display 1, that is, in the case of 8 parallaxes, The sum of the distances between the 4 parallax and the 4 parallax rays and the sum of the parallax images at both ends of the display end, that is, the distance between the -8 parallax and -1 parallax rays are the same. This is good because the intensities of the light rays at the center and the edge at the viewing distance are averaged.
[0064]
FIG. 17 shows the resolution dependency of the pixel size and the gap d, which is the distance between the light beam display 1 and the light beam control element, at the resolution αimax determined by the light beam density per opening. P in FIG._pIndicates the pixel size, but when the pixel size decreases, the pitch p of the openings_eTherefore, the resolution near the light beam control element is improved.
[0065]
Here, it can be seen from FIG. 13 that the resolution improves as the gap d increases, but there is a problem that the viewing zone angle decreases as the gap d increases. In the case of a concave curved surface display, since the originally visible range is small, even if the viewing zone angle 2θ is small, it is natural that the viewing zone 5 becomes narrow as shown in FIG. Therefore, it is possible for the concave curved display to improve the resolution by narrowing the viewing zone angle.
[0066]
From the above, the main factors that increase resolution
1) Effect of the display edge protruding forward
2) The effect of reducing the horizontal size of the pixels due to the tilting of the display.
3) Since the angle of view of the display has become smaller, the beam bundle at the end of the display can be assigned to the same size as the angle at which the observer's screen is desired, and the viewing zone area away from the display has increased. Raised.
[0067]
As shown in FIG. 19, when the display 1 is an LCD (Liquid Crystal Display), the rising angle θ of the liquid crystal molecules 36 in a direction in which the display surface is viewed in front._mIs designed to maximize. For example, normally white is designed to be darkest when the display 1 is viewed from the front. In FIG. 19, reference numeral 15 indicates a pixel, and reference numeral 37 indicates a liquid crystal layer.
[0068]
For this reason, in the case of this embodiment, since it is assumed that the display 1 is inclined, the inclination angle θ_YTherefore, if the contrast is designed to be maximized, the image quality becomes better. Therefore, the tilt angle θ which is the rising angle of the liquid crystal molecules_mIs the tilt angle of tilted display and concave curved display_YAnd the angle between the parallax image at the center of the parallax image group and the observer and the display 1 when viewed from the front._ZThen, from FIG.
θ_m= Θ_Y−θ_Z
It is desirable that
[0069]
Also, by lowering the voltage applied to the liquid crystal layer 37 instead of the maximum value, the rising angle of the liquid crystal molecules 36 can be made oblique, and the contrast when viewed from the observer of the concave curved surface display or the tilted display is maximized. Can be designed to
[0070]
As described above, according to the present embodiment, the display has a concave curved surface, or a plurality of inclined displays are arranged so as to face the observer, without changing the horizontal pixel size. The apparent horizontal pixel size can be reduced, and the viewing area in the direction away from the display can be increased as shown in FIG.
[0071]
FIG. 20 shows the configuration of the third modification of the present embodiment. As shown in FIG. 20, the display 1 and the light beam control unit 8 are formed such that a plurality of flat display surfaces form part of a polygon as viewed from the observer 4, and these display surface groups are seamlessly connected. Even in such a configuration, the effect of increasing the resolution can be seen.
[0072]
(Second Embodiment)
Next, FIG. 21 shows a configuration of a stereoscopic image display apparatus according to the second embodiment of the present invention. This embodiment has a configuration in which the display 1 and the light beam control unit 8 are formed in a convex curved shape when viewed from the observer 4 in the stereoscopic image display device of the first embodiment. For this reason, since the position of the center part is ahead of the end, the resolution of the center part is increased. As for the edge, since the position is behind, when a stereoscopic image is displayed forward, the resolution of the image through the opening at the edge or the lens array is lowered. However, since the observer 4 views the image from an oblique direction, the resolution displayed by the effect described above increases. Therefore, the boundary 42 of the resolution limit at which the stereoscopic display can be normally displayed can be set at the same position on the entire screen as compared with the boundary 42 shown in FIG. 11, and there is an advantage that a stereoscopic display image can be easily created.
[0073]
(Third embodiment)
FIG. 22 shows a configuration of a stereoscopic image display device 3 according to the third embodiment of the present invention. In this embodiment, in the stereoscopic image display device according to the first embodiment, the display 1 and the light beam control unit 8 have a plurality of (two in this embodiment) planar display surfaces in a convex shape as viewed from the observer 4. It is formed so as to form a part of a square. Even when the display surface groups have display surfaces that are seamlessly connected, the effect of increasing the resolution can be seen. Moreover, it is effective when it is desired to emphasize the resolution at the center as in the second embodiment shown in FIG.
[0074]
(Fourth embodiment)
FIG. 23 shows a cross-sectional view of the curved display 1 used in the stereoscopic image display apparatus of the present invention, and a creation method will be briefly described as a fourth embodiment. For example, a conventional liquid crystal display device or the like cannot be bent on a curved surface because a liquid crystal layer is sandwiched between thick glass substrates.
[0075]
Therefore, after a TFT (Thin Film Transistor) 45 is formed on the glass substrate 43 by a normal process, the glass substrate is thinned with an appropriate abrasive, and then a PES substrate or a plastic substrate as the support substrate 44 is bonded. The structure can be made flexible. In the case of a TN liquid crystal, the change in the thickness of the liquid crystal layer due to bending greatly affects the voltage value for determining the transmittance of the liquid crystal, so the thickness should be uniform. Therefore, by inserting the spacer 51, the thickness of the liquid crystal layer 52 is made constant everywhere. In addition, when the color filter is applied to the counter substrate 48 having the counter electrode 47, a positional shift or the like occurs when it is bent. Therefore, the color filter 46 is preferably formed on the substrate 43 on the TFT side. In some cases, the liquid crystal layer 52 may have the maximum brightness in the oblique direction in order to direct the exit direction from the opening or the lens array 50 to the observer. Therefore, the tilt angle of the liquid crystal may be tilted in advance toward the observer, or a liquid crystal material having a high viewing angle may be selected. Next, since it is necessary for light control to maintain a constant gap between the lens array 50 or the light beam control unit having the opening and the display, the plastic is transparent, has a uniform thickness, and can be bent to some extent. A substrate may be used, or a plastic substrate (49) on a film or a thin acrylic substrate may be placed through a certain spacer.
[0076]
As described above, according to the present embodiment, the pixel array is observed obliquely by arranging a plurality of displays that are concave or convex when viewed from the viewpoint, or are tilted when viewed from the observer. As a result, the apparent pixel pitch can be improved, and the resolution of the pop-out area can be improved. Even if the viewing zone angle is narrowed with the same number of parallaxes, the viewing zone in the direction away from the screen can be expanded to infinity by the above structure. Optimization of the desired pop-out resolution can be designed by optimizing the slit spacing, the radius of curvature, the curvature angle, and the inclination angle of the polygon.
[0077]
【The invention's effect】
As described above, according to the present invention, even when a three-dimensional image is reproduced at a position away from the display surface, the viewing area is narrowed in the direction away from the screen with reference to the observer without reducing the resolution. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a horizontal sectional view showing a configuration of a stereoscopic image display apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining the effect of the first embodiment.
FIG. 3 is a view for explaining a place-specific parallax image group of a display according to the first embodiment;
FIG. 4 is a horizontal sectional view showing the positional relationship between the opening and the display pixel in the vicinity of the center of the tilted display according to the first embodiment.
FIG. 5 is a horizontal sectional view showing the positional relationship between the opening and the display pixel at the end of the tilted display according to the first embodiment.
FIG. 6 is a conceptual diagram showing the positional relationship between the central portion of the tilted display according to the first embodiment, the opening at the screen edge, and the parallax image.
FIG. 7 is a conceptual diagram showing a parallax image number group at an arbitrary position of the tilted display according to the first embodiment.
FIG. 8 is a conceptual diagram showing a configuration of a seam portion when there is a seam between inclined displays according to the first embodiment.
FIG. 9 is a horizontal sectional view showing a configuration of a stereoscopic image display device according to a first modification of the first embodiment.
FIG. 10 is a horizontal sectional view showing a configuration of a stereoscopic image display apparatus according to a second modification of the first embodiment.
FIG. 11 is a schematic diagram showing a pop-out limit with respect to a resolution threshold value of the concave curved surface display according to the first embodiment and the conventional flat display.
FIG. 12 is a diagram showing the distance dependency of the resolution from the observation point when the concave curved surface display according to the present embodiment is used.
FIG. 13 is a diagram showing the distance dependency from the observation point of the average resolution of this embodiment and the conventional example.
FIG. 14 is a diagram illustrating a parallax image assignment method for a concave display according to the present embodiment.
FIG. 15 is a diagram showing a boundary of parallax number assignment for preventing crosstalk when the concave display according to the present embodiment is used.
FIG. 16 is a ray trajectory diagram when a concave curved surface is created by an ellipse.
FIG. 17 is a diagram showing a relationship between a gap interval between a concave curved surface display and a light beam control element and a resolution α determined from a light beam density per opening.
FIG. 18 is a horizontal sectional view showing the viewing area of the concave curved surface display according to the first embodiment.
FIG. 19 is a diagram for explaining a preferred tilt angle of liquid crystal molecules when the display is a liquid crystal display device.
FIG. 20 is a horizontal sectional view showing a configuration of a third modification of the stereoscopic image display device according to the first embodiment;
FIG. 21 is a horizontal sectional view showing a configuration of a stereoscopic image display apparatus according to a second embodiment of the present invention.
FIG. 22 is a horizontal sectional view showing a configuration of a stereoscopic image display apparatus according to a third embodiment of the present invention.
FIG. 23 is a cross-sectional view illustrating a method for manufacturing a liquid crystal display device having a concave curved surface display according to the present invention.
FIG. 24 is a diagram for explaining binocular parallax.
FIG. 25 is a horizontal sectional view for explaining the principle of performing stereoscopic display by the IP method in a conventional stereoscopic image display apparatus.
FIG. 26 is a horizontal sectional view for explaining the resolution by the Nyquist frequency in the IP method.
FIG. 27 is a horizontal sectional view for explaining the resolution of a parallax image group of an aerial image of the IP method.
FIG. 28 is a horizontal sectional view showing a viewing area of a conventional stereoscopic image display device.
FIG. 29 is a horizontal sectional view for explaining a problem of a conventional stereoscopic image display device.
[Explanation of symbols]
1 Two-dimensional image display device (display)
2 opening
3 Shielding part
4 observers
5 Viewing zone where normal images can be seen
7 rays
8 Light beam control unit
11 Areas where no false images are seen at viewing distance
13 Object image to be displayed in 3D
14 pixels
17 Right edge of display
18 Left edge of display
19 When an observer stands at a position where the two-sided display can be viewed symmetrically, a line drawn from there toward the center of the display
21 A group of parallax images emitted from one opening
23 Spread of parallax image at parallax distance
25 Deviation between the edge of the parallax image group and the opening
100 Surface perpendicular to the viewing distance plane
102 Viewing distance plane

Claims (4)

A display unit in which pixels positioned in a concave or convex display surface as viewed from the observer are arranged in a matrix, and a two-dimensional pattern display means for displaying a two-dimensional pattern on the display surface of the display unit And a light beam control unit that has a plurality of apertures or a plurality of lenses and controls the direction of the light beam from the pixel,
The display unit includes at least two planar display surfaces connected seamlessly , and the display surface of the display unit is divided into element images corresponding to the openings or the lenses of the light beam control unit. And
The stereoscopic image display device , wherein the opening pitch of the light beam control unit or the lens pitch is an integral multiple of the pixel pitch of the display unit.   From the opening of the light beam control unit or the center of the lens, the position where the perpendicular line dropped on the display surface intersects the display surface and the position of the center of the parallax image are shifted according to the tilt angle of the display surface, The stereoscopic image display device according to claim 1, wherein the shift amount is different between an end portion and a center portion of the display portion.   From the opening of the light beam control unit or the center of the lens, the position where the perpendicular line dropped on the display surface intersects the display surface and the position of the center of the parallax image are shifted according to the tilt angle of the display surface, The stereoscopic image display apparatus according to claim 1, wherein the parallax image group at an end of the display unit is shifted in an end direction of the display unit with respect to a center of the opening. The display unit is a liquid crystal display device, and an inclination angle between a tangent of an arbitrary point on the display surface of the display unit and a plane parallel to the viewing distance plane is θ _Y , and an arbitrary opening and the center of the viewing distance plane And θ _Z is the angle formed by the line connecting the opening and the line connecting the opening and the viewing distance surface with the shortest distance, the maximum tilt angle θ _M of the liquid crystal molecules is θ _M = θ _Y −θ _Z
The stereoscopic image display device according to claim 1, wherein the stereoscopic image display device is configured as follows.

Images