JP2018010055A - Image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display system that efficiently improves resolution of three-dimensional images.SOLUTION: An image display system comprises a plurality of image projection units, a light control lens, and a lens array. Each of the plurality of image projection units projects an element image on a projection surface. The light control lens is disposed in parallel with the projection surface to converge incident projection light from the plurality of image projection units. The lens array comprises a plurality of arrayed element lenses for converging incident projection light from the light control lens. A distance between the projection surface and the light control lens equals a distance between the light control lens and a focal length (focal point).SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image display system.

  There is an integral method for displaying a stereoscopic image. The principle is that the light beams of a plurality of element images that are the basis of a stereoscopic image are presented through a lens array including corresponding element lenses. The element image is an image representing a common subject acquired at each viewpoint. The image of the subject represented by the light rays of each element image is formed at the position where the subject exists. Therefore, natural three-dimensional display of the subject becomes possible. The integral method is sometimes called an IP (Integral Photography) method. Hereinafter, a stereoscopic image displayed by the integral method may be referred to as an integral stereoscopic image or simply a stereoscopic image.

  Integral stereoscopic images are expected to improve in quality, such as improved resolution, expanded viewing zone, and improved depth reproduction performance. However, for example, it is difficult to apply the integral method to a high-definition video having a resolution exceeding 8K. This is because high quality requires a high-definition element image and a minute element lens.

  Therefore, a method for improving the quality of an integral stereoscopic image using a plurality of projectors has been proposed. For example, Non-Patent Document 1 describes a method of expanding a stereoscopic image viewing area using a plurality of projectors. In the method described in Non-Patent Document 1, the components are arranged such that stereoscopic viewing zones formed by a plurality of projectors are continuously connected.

  Non-Patent Document 2 proposes a method for improving the resolution of an integral stereoscopic image using a plurality of projectors. In this method, each of the plurality of projectors directly projects the projection light of the element image onto the lens array. The element lens forming the lens array collects the projection light and forms a plurality of bright spots on the output surface. The number of bright spots corresponds to the number of pixels of the integral stereoscopic image. The resolution can be improved by increasing the number of projectors.

Hisayuki Sasaki, Masato Miura, Satoshi Washi, Proceedings of 2012 Annual Conference of the Institute of Image Information and Television Engineers, “Integrated stereoscopic image display with multiple viewing areas using multiple MEMS laser projectors”, 14-8, 2012 8 29th of May Yamazaki Tadashi, Koike Takafumi, Utsugi Satoshi, 3D Image Conference 2008, "Light Field Densification Technology Using Multiple Real Images and Deflection Optical System", 4-4, July 10, 2009

  However, in the method described in Non-Patent Document 1, in order to improve the resolution of the integral stereoscopic image, a finer element lens and a higher-density display device are required. Therefore, it is difficult to further increase the definition. Further, according to the method described in Non-Patent Document 2, the element image in each viewpoint direction is directly projected onto the lens array, so that the projection light spreads away from the projector. The number of bright spots and the distribution of positions are not uniform in the screen, and differ depending on the observation position. For this reason, the resolution of the integral stereoscopic image cannot always be improved efficiently. Further, since the projector arrangement and the light projection direction to the lens array are not uniform, it is necessary to create an element image in accordance with the measurement after the light beam reproduced by the display device is measured.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an image display device that can efficiently improve the resolution of a stereoscopic image.

The present invention has been made to solve the above-described problems. [1] One aspect of the present invention is a plurality of projection units that project element images on a projection surface, and are arranged in parallel with the projection surface. And a light control lens for converging the projection light incident from the plurality of projection units, and a lens array in which a plurality of element lenses for converging the projection light incident from the light control lens are arranged, and the projection The distance between the surface and the light control lens is equal to the focal length of the light control lens.
According to the configuration of [1], the projection light from the plurality of projection units that pass through the light control lens becomes parallel light and enters the element lens. On the surface on which the focus of each element lens is distributed, the light rays that form part of the projection light from the plurality of projection units that have passed through the element lens converge to form a bright spot. Bright spots that act as pixels representing a stereoscopic image are formed spatially denser than the focal points of the element lenses, and projection light from each bright spot is emitted in a superimposed manner. Therefore, the resolution of a three-dimensional image can be improved without reducing the diameters of the projection elements and element lenses of the projection unit.

[2] One aspect of the present invention is the above-described image display system, wherein the plurality of projection units are arranged at regular intervals in at least one direction on the projection surface, or the plurality of projection units are , One direction on the projection surface and the other direction intersecting the one direction are arranged at a constant interval for each direction, and the interval is an interval between adjacent element lenses and the focal length of the element lens It is characterized by being 1 / N of the distance obtained by multiplying the focal length ratio of the light control lens (where N is an integer of 2 or more).
According to the configuration of [2], a bright spot is formed at each equally divided point in the direction in which the projection unit is arranged on the front focal plane in which the distance in the direction in which the projection light from the lens array travels becomes the focal length. . Since the positions of the bright spots formed by the plurality of projection units are uniform, the resolution of the stereoscopic image is improved, and the projection images are projected from different projection directions by the plurality of projection units to form the bright spots, so that the stereoscopic image is observed. The viewing area can be enlarged.

[3] One aspect of the present invention is the above-described image display system, wherein the optical axis directions of the plurality of projection units are parallel to the optical axis directions of the plurality of element lenses, respectively.
According to the configuration of [3], the projection light representing the element image from each projection unit enters the optical axis direction of each element lens. Therefore, the entire element image from each projection unit is formed on the rear focal plane where the distance in the direction in which the projection light is received from the lens array is the focal length. Since the entire element images obtained by integrating the light rays coming from the respective bright spots are observed while being superimposed on each other, the stereoscopic image is surely visually recognized.

[4] One aspect of the present invention is the above-described image display system, wherein projection light incident from the plurality of projection units is based on a position of a bright spot formed through the plurality of element lenses. An image acquisition unit that acquires, as the element image, an image obtained by observing a subject common to the plurality of projection units from different viewpoints.
According to the configuration of [4], a bright spot formed on the back focal plane is generated as a pixel of an element image representing a common subject observed from each viewpoint. Since the position of each bright spot is uniquely determined based on the position of the projection unit, an element image to be projected on the projection unit can be easily produced.

  According to the present invention, it is possible to efficiently improve the resolution of a stereoscopic image and to enlarge the viewing zone.

It is a block diagram which shows the structural example of the image display system which concerns on embodiment of this invention. It is a figure which shows an example of the optical arrangement | positioning of the image display system which concerns on embodiment of this invention. It is a figure which shows an example of the positional relationship between the components of the image display system which concerns on embodiment of this invention. It is a figure which shows the example of a general arrangement | positioning of the projector unit which concerns on embodiment of this invention. It is a front view which shows the example of the arrangement pattern of the bright spot formed with the image display system which concerns on embodiment of this invention. It is a front view which shows the example of arrangement | positioning of the projector unit in the image display system which concerns on embodiment of this invention. It is a side view which shows the example of arrangement | positioning of the projector unit in the image display system which concerns on embodiment of this invention. It is a figure which shows the example of the viewing zone by the image display system which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration example of an image display system 1 according to the present embodiment.
The image display system 1 includes a stereoscopic video generation unit 10, a video recording / playback unit 11, a projector array 12, a light control lens 13, and a lens array 14. The projector array 12 includes a plurality of projector units and is formed by arranging them in a predetermined direction. The lens array 14 includes a plurality of element lenses and is formed by arranging them in a common plane.

  The stereoscopic video generation unit 10 generates a plurality of element images representing a stereoscopic video. The stereoscopic video generation unit 10 generates an element image representing a common subject having a different viewpoint for each projector unit based on the three-dimensional data indicating the stereoscopic shape of the subject, the position of each projector unit, and the characteristics of the lens array 14. To do. The characteristics of the lens array 14 include requirements for determining the position of a bright spot (described later), such as the lens pitch, the position of each element lens, and the focal length. The lens pitch is an interval between adjacent element lenses. A bright spot is a point corresponding to a pixel representing a stereoscopic image, and is formed for each set of projector unit and element lens. Therefore, the stereoscopic video generation unit 10 generates an image in which a common subject is observed from different viewpoints for each projector unit, and an image represented by using a plurality of bright spots related to the projector unit as an element image. The stereoscopic video generation unit 10 outputs element image data indicating the generated element image to the video recording / playback unit 11.

  The video recording / playback unit 11 includes a storage medium that records element image data for each projector unit input from the stereoscopic video generation unit 10. The video recording / playback unit 11 outputs the element image data recorded in the storage medium or the element image data input from the stereoscopic video generation unit 10 to the corresponding projector unit.

  The projector units constituting the projector array 12 generate light beams representing the element images indicated by the element image data input from the video recording / reproducing unit 11 and project the generated light beams onto the light control lens 13. Hereinafter, the light beam projected by the projector unit is referred to as projection light.

  The light control lens 13 controls the spread of the projection light incident from each projector unit, and makes the transmitted projection light parallel light. The projection light transmitted from the light control lens 13 is projected onto the lens array 14. Light rays that form part of the projection light of the element image are transmitted from each element lens forming the lens array 14. An integral 3D image representing the 3D shape of the subject can be visually recognized by observing the element images, which are part of the element image represented by the transmitted light beam, integrated between the element lenses so as to overlap each other. The Assuming that the shape of the light control lens 13 is a spherical surface, the parallelism of light rays incident and transmitted obliquely may decrease as the incident angle increases. Therefore, the shape of the light control lens 13 is not limited as long as the transmitted light beam has a shape that allows the transmitted light beam to be sufficiently close to the parallel light beam or the parallel light beam within the range of the incident angle where the light beam is incident from the projector unit. It may be spherical. The light control lens 13 is, for example, a Fresnel lens. By adopting a Fresnel lens, it is not necessary to increase the thickness even if the screen is enlarged. This is because the size of the light control lens 13 is required to be equal to the size of the screen.

(Optical arrangement)
Next, an example of the optical arrangement of the image display system 1 according to the present embodiment will be described.
FIG. 2 is a diagram illustrating an example of an optical arrangement of the image display system 1 according to the present embodiment.
In the example illustrated in FIG. 2, the projector array 12 includes N projector units 12 _{1 to} 12 _N. N is an integer of 2 or more. Further, in FIG. 2, illustration of the stereoscopic video generation unit 10 and the video recording / playback unit 11 is omitted.

The projector array 12 is arranged such that the distance in the optical axis direction from the light control lens 13 is equal to the focal length F. The focal length F is the focal length of the light control lens 13. That is, the projector unit ₁₂ 1 to 12 projector distance becomes equal to the focal length position of the respective optical center and the light control lens 13 of _N unit ₁₂ 1 to 12 _N is arranged. In the following description, a plane on which the optical centers of the projector units 12 _{1 to} 12 _N are arranged is referred to as a projection surface. The projection surface is parallel to the direction in which the light control lens 13 is arranged. With this arrangement, the projection light from each of the projector units 12 _{1 to} 12 _N that passes through the light control lens 13 becomes parallel light. Projection light from the light control lens 13 and the projector units 12 ₁ and 12 ₂ represented by broken lines and solid lines in FIG. ₂ passes through the light control lens 13 and is projected onto the lens array 14 as parallel light.

The plurality of element lenses constituting the lens array 14 are arranged so as not to overlap each other in a common plane. In the following description, a plane on which element lenses are arranged is referred to as an arrangement plane. The direction of the optical axis of the element lens is a direction perpendicular to the arrangement plane. Each element lens is formed of a convex lens that converges a light beam that forms part of the projection light transmitted through the light control lens 13. On the other hand, the incident angle of the projection light transmitted through the light control lens 13 to the lens array 14 varies depending on the positions of the projector units 12 _{1 to} 12 _N. Since each projection light is parallel light, the light rays transmitted through each element lens converge at different positions to form a bright spot. Of these, the light rays incident in the direction of the optical axis converge at the focal point of each element lens. The bright spots that are formed are distributed on a plane on which the focal points are distributed. In the following description, the plane in which the focal point is distributed in the direction in which the projection light is transmitted through the lens array 14 is referred to as the front focal plane 15, and the plane in which the focal point is distributed in the light control lens 13 rather than the lens array 14 is the rear focal plane 17. Call it. Therefore, the distance from the arrangement plane of the lens array 14 to each of the front focal plane 15 and the rear focal plane 17 is equal to the focal length of each element lens. Further, the projection light from each of the projector units 12 _{1 to} 12 _N is focused on the rear focal plane 17. Therefore, element images from the projector units 12 _{1 to} 12 _N are projected onto the rear focal plane 17, and a part of the element image is formed on the main surface of each element lens. A part of the element image formed on each element lens is a unit capable of controlling the parallax between the projector units 12 _{1 to} 12 _N , and corresponds to a pixel constituting the element image. In the following description, a part of this element image may be called an element image unit.

In the example illustrated in FIG. 2, the broken line and the solid line indicate the projection light projected from the projector units 12 ₁ and 12 ₂ , respectively. Projection light from the projector unit 12 _2, converges on the focal indicated by ○ mark to incident parallel to the optical axis of the element lenses. Projection light from the projector unit 12 ₁ is parallel incident from above the optical axis of the element lens. The light beam that has passed through the element lens converges to the bright spot indicated by the Δ mark. The bright spots are distributed in the front focal plane 15, but are formed below the focal point. Thus, the bright spot based on the projection light from each projector unit 12 _{1 to} 12 _N can be formed at a position different from the focal point of the element lens. Rays representing element pixel units converged at each bright spot are radiated to the viewing space, and element pixels formed by integrating element pixel units between element lenses are observed by being superimposed between projector units, A stereoscopic image is visually recognized. As described above, the bright spot corresponds to an element image unit that forms a stereoscopic image. Therefore, the resolution of the integral stereoscopic image can be improved by distributing the bright spots more densely than the focal points of the element lenses and making the intervals uniform. The position of the bright spot depends on the positional relationship between the components of the image display system 1 as described below.

Next, the positional relationship between the components of the image display system 1 according to the present embodiment will be described. FIG. 3 is a diagram illustrating an example of a positional relationship between components of the image display system 1 according to the present embodiment. In the example shown in FIG. 3, the number of projector units constituting the image display system 1 is three. The three projector units 12 _{1 to} 12 ₃ are arranged in that order at regular intervals in a line in the x direction. Here, the x direction is a vertical direction on the projection plane orthogonal to the direction of the optical axis of the light control lens 13. Optical center of the projector unit 12 ₂ is disposed on the optical axis of the light control lens 13. The positions of the optical centers of the projector units 12 ₁ and 12 ₃ are positions separated from the optical center of the projector unit 12 _{2 by} a distance L in the x direction. The distance in the optical axis direction of the light control lens 13 from the projector units 12 _{1 to} 12 ₃ to the light control lens 13 corresponds to the focal length F of the light control lens 13. Therefore, the projection angle θ from the projector units 12 ₁ to the light control lens 13 is given as the formula (1), corresponding to the arctangent of the ratio of the distance L with respect to the focal length F.

Projection angle θ is the direction of the optical center from the principal point H _L1 of the projector unit 12 ₁ of the light control lens 13 is an angle formed between the direction of the optical axis A _L1 of the light control lens 13. Projection light from the projector unit 12 _1, the parallel light passes through the light control lens 13. The projection light transmitted through the light control lens 13 also enters the lens array 14 at an incident angle corresponding to the projection angle θ. Then, the element lens of the lens array 14 converges the light beam that forms part of the projection light incident in the direction away from the optical axis by the projection angle θ, and a bright spot is formed on the front focal plane 15. On the other hand, the projected light from the projector unit 12 ₂ is transmitted in the direction of the optical axis A _L1 of the light control lens 13, that direction is the same as the direction of the optical axis of the element lenses of the lens array 14. Therefore, light rays which form a part of the projection light from the projector unit 12 ₂ which has passed through the element lens is converged at the focal point of the element lenses, bright spots are formed. In FIG. 3, the bright spots based on the projection lights of the projector units 12 ₁ , 12 ₂ , and 12 ₃ are represented by Δ marks, ◯ marks, and □ marks. The distance m between the luminescent spots by the projection light of each of the projector units 12 ₁ and 12 ₂ is the distance L and the focal length of the element lens with respect to the focal length F of the light control lens 13 as represented by the equation (2). It corresponds to the distance obtained by multiplying by the ratio of f.

In order to set the distance m between the bright spots to be equal to the lens pitch p, ie, m = p / 2, the distance L may be set to p · F / (2 · f). The lens pitch p is a distance between element lenses adjacent to each other. The distance between the bright spots based on the projection lights of the projector units 12 ₂ and 12 ₃ is also m.
Further, when the bright spots based on the projection lights of the projector units 12 _{1 to} 12 ₃ are set to be equally divided into three, that is, m = p / 3 within the lens pitch p, the distance L is set to p · F. / (3 · f) may be set.

Next, it is generalized when 2N + 1 projector units 12 _{-N to} 12 _N are arranged in that order in the x direction. In the example described below, N is an integer of 1 or more. FIG. 4 is a diagram showing a generalized arrangement example of the projector unit according to the present embodiment. In the example shown in FIG. 4, the optical center of the projector unit 12 ₀ it is disposed on the optical axis of the light control lens 13. The projection angle θ _{+ n} from the projector unit 12 _n to the light control lens 13 is given by Expression (3).

In Expression (3), L _{+ n} indicates the distance in the x direction from the light control lens 13 to the optical center of the projector unit 12 _n . The distance m _{+ n} from the focal point of the element lenses to a bright spot based on the projection light of the projector unit 12 _n is given by equation (4).

Therefore, the bright spot interval Δs between the bright spot based on the projection light of the projector unit 12 _{n and} the bright spot based on the projection light of the projector unit 12 _n−1 adjacent to the bright spot is given by Expression (5).

In the formula (5), [Delta] L indicates the distance between the optical center and the projector unit _{12 n-1} of the optical center of the projector unit 12 _n. Equation (5) indicates that the bright spot interval Δs is obtained by multiplying the ratio of the focal length d of the element lens to the focal length F of the light control lens 13 of the interval ΔL between the projector units.
Therefore, in order to form a bright spot at a position where the lens pitch p is equally divided into M, that is, a position where Δs = p / M, M + 1 or M projector units may be evenly arranged at an interval ΔL. M is an integer of 2 or more. At this time, the distance ΔL is obtained by multiplying the lens pitch p by the ratio F / f of the focal length F of the light control lens 13 to the focal length f of the element lens, as given by Expression (6). This is a value obtained by dividing F / f into M equal parts.

  As described above, in the examples illustrated in FIGS. 2 to 4, the bright spots formed when the projector units are arranged in the x direction are exemplified, but the present invention is not limited thereto. When the projector units are arranged in the y direction, the relationship between the spacing between the projector units and the spacing between the bright spots can be similarly derived when the projector units are two-dimensionally distributed in the xy plane. it can. Here, the xy plane indicates the projection plane described above. The y direction is a direction orthogonal to the x direction in the xy plane, that is, a horizontal direction.

(Example of bright spot arrangement pattern)
Next, an example of the arrangement pattern of bright spots formed at equal intervals in the front focal plane 15 will be described. In the example shown in FIG. 5A, the arrangement pattern of the bright spots is a square arrangement. That is, the bright spots are arranged at equal intervals in the x and y directions on each square lattice point. Square area indicated by a broken line is a region where the center is the focal point f ₀ of each one element lens. A square corresponds to a unit figure of a square lattice formed periodically and repeatedly. Each region corresponds to a respective element lens. One region includes four bright spots. In FIG. 5A, a, b, c, and d respectively indicate bright spots based on the projection light of the projector unit. bright point interval Δx in the x direction corresponds to half the x-direction of the lens pitch _{p x.} bright point interval Δy in the y direction corresponds to 1/2 of the lens pitch _{p y} in the y direction. In the example shown in FIG. 5A, the bright spot interval Δx in the x direction is equal to the bright spot interval Δy in the y direction.

In the example shown in FIG. 5B, the arrangement pattern of the bright spots is a delta arrangement. The delta arrangement is an arrangement in which the line interval is half of the bright spot interval in each row, and the shift of the bright spot position between adjacent rows is half of the bright spot interval in each row. The bright spot intervals in the x and y directions are 2Δx ′ and 2Δy ′, respectively. Δx ′ is equal to Δy ′. In the xy plane, the bright spot interval in the direction inclined 45 degrees counterclockwise from the x direction is √2Δx ′. In the following description, the direction inclined 45 degrees is referred to as a crossing direction. A square area corresponding to each element lens includes 13 bright spots. In FIG.5 (b), a'-m 'shows the bright spot based on the projection light of a projector unit, respectively. The bright spot g ′ is formed at the position of the focal point f ₀ ′ of the element lens. x-direction of the bright point interval 2Derutax 'corresponds to half the x-direction of the lens pitch _{p x.} y-direction of the bright point interval 2Derutawai 'corresponds to 1/2 of the lens pitch _{p y} in the y direction. Moreover, the bright point interval √2Δx cross direction 'is equivalent to 1 / 2√2 lens pitch _{p x.}

(Projector unit layout example)
Next, an arrangement example of the projector unit will be described.
6 (a) shows an example of the arrangement of the projector unit ₁₂ a to 12 _d. The position of the optical center of the projector units 12 _{a to} 12 _d is arranged at each vertex of a square corresponding to the unit graphic on the projection surface. The arrangement direction of the bright spots _a to _{d in} the xy plane is opposite to the arrangement direction of the corresponding projector units 12 _{a to} 12 _{d in} the xy plane. More specifically, the projector units 12 _{a to} 12 _d are arranged in the order from the bottom to the top and from the right to the left, whereas the bright spots _a to _d are from the top to the bottom and from the left to the right. It is arranged in the order. The center point F ₀ of the bright spots a to d is a point corresponding to the focal point f _{0 of the} element lens. Further, the intervals ΔL _x and ΔL _y between projector units adjacent in the x and y directions are Δx · F / f and Δy · F / f, respectively. When expressed using the lens pitches p _x and p _y , the intervals ΔL _x and ΔL _y are p _x · F / (2 · f) and p _y · F / (2 · f), respectively. Therefore, the width in the x direction around the center point _{F 0} is _p x · F / f, in the region of the square width in the y direction is _p y · F / f projector unit ₁₂ a to 12 _d are disposed By doing so, crosstalk is avoided.

FIG. 6B shows an arrangement example of the projector units 12 _{a ′ to} 12 _{m ′} . The positions of the optical centers of the projector units 12 _{a ′ to} 12 _{m ′} arranged on the projection surface respectively correspond to the bright spots _{a ′} to _{m ′} shown in FIG. Therefore, the arrangement of the projector units 12 _{a ′ to} 12 _{m ′} is also a delta arrangement. Further, the arrangement direction of the projector units 12 _{a ′ to} 12 _{m ′} is opposite to the arrangement direction of the bright spots _{a ′} to _{m ′} . The position of the optical center of the projector unit 12 _{g ′} corresponds to the center point F ₀ ′ of the projector units 12 _{a ′ to} 12 _{m ′} . The bright spot g ′ of the projection light from the projector unit 12 _g ′ is located at the focal point f ₀ ′ of the element lens. A distance in the x direction between the optical centers of the two projector units, for example, a distance ΔL _x ′ between the projector units 12 _{j ′} and 12 _l ′ is Δx ′ · F / f. Further, a distance in the y direction between the optical centers of the two projector units, for example, a distance ΔL _y ′ between the projector units 12 _{h ′} and 12 _j ′ is Δy ′ · F / f. The distance ΔL _xy ′ between the optical centers of the two projector units is √2Δx ′ · F / f. Lens pitch _p x, expressed using _{p y,} distance _{ΔL x, ΔL y, ΔL x} -y _{is, p x · F / (4} · f) , respectively, p y · F / (4 · f), p _x · F / (2√2 · f). That is, in the arrangement pattern of the projector unit shown in FIG. 6B, one square arrangement is shifted from the other square arrangement by √2ΔL _x ′ in the crossing direction, and the intervals in the x and y directions of the square arrangements are different. 2ΔL _x ′, 2ΔL _y ′. In this example, the center point _{F 0} 'width x direction around the _p x · F / f, y direction width _p y · F / f become projector unit 12 in a square in the area _a' ~ By arranging 12 _{m ′} , crosstalk is avoided.

In the example shown in FIG. 5B, the bright points a ′, c ′, k ′, and m ′ are also vertices of the regions corresponding to the other three element lenses. Therefore, any three projector units 12 _{a ′} , 12 _{c ′} , 12 _{k ′} , and 12 _{m ′} may be omitted. Further, the bright spots b ′ and l ′ are on the sides of the region corresponding to the element lens adjacent above and below the element lens of interest. Therefore, any one of the projector units 12 _{b ′} and 12 _{l ′} may be omitted. Further, the bright spots f ′ and h ′ are on the sides of the region corresponding to the element lens adjacent to the left and the right, respectively, with respect to the element lens of interest. Therefore, either 12 _{f ′} or 12 _{h ′} may be omitted. For example, among the projector units 12 _{a ′ to} 12 _{m ′} , the projector units 12 _{c ′} , 12 _{h ′} , 12 _{k ′} , 12 _{l ′} , and 12 _{m ′} may be omitted.

As described above, it is desirable that the element image projected from each projector unit is formed in the rear focal plane 17. For example, assume a case of arranging tilting the projector unit 12 _x projection optical axis A _P1 of the direction crossing the optical axis A _L2 of element lenses constituting the lens array 14 as shown in FIG. 7 (a) . The imaging plane 17 ′ on which the element image projected by the projector unit 12 _x forms an image is orthogonal to the optical axis AP ₁ , and therefore tilts with respect to the rear focal plane 17. Therefore, the entire element image is not formed on the rear focal plane 17.

Therefore, in this embodiment, as shown in FIG. 7 (b), the projection optical axis A _P1 of the projector unit 12 _x, is arranged parallel to the optical axis A _L2 of element lenses constituting the lens array 14. In other words, the direction of the projection optical axis A _P1, with the direction of the optical axis A _L1 of the light control lens 13 is installed in parallel. Then, in the projector unit 12 _x , the center point of the video display element 18 _x is shifted from the optical axis _AP1 by a predetermined distance and arranged. Thereby, even _if the projection light from the image display element 18 _x is projected through the light control lens 13 in the direction intersecting the optical axis _AL2 , the element image can be formed on the rear focal plane 17. In the example shown in FIG. 7B, the displacement d (shift amount) of the image display element 18 _{x from} the optical axis AP _{1 is set} to a ratio d / of the focal length f _p of the projection lens 19 _x of the projector unit 12 _x. f _p is, may be set so that the tangent tanθ projection angle θ with respect to the optical axis a _L2 of the projected light.

Display characteristics such as resolution, luminance range, and color gamut may be common among a plurality of projector units constituting the image display system 1. Thereby, the change by the viewpoint of the quality of the stereo image visually recognized by superimposing the element image based on the projection light from each projector unit decreases. Elements of stereoscopic image quality include brightness, color, depth reproduction performance, and the like. Note that the display characteristics are not necessarily common among the plurality of projector units. For example, the resolution may be different between projector units. A projector unit having a higher resolution is used for a projector unit arranged so that the projection angle θ of the projection light with respect to the optical axis A _L2 is close to 0, and a resolution is lower for a projector unit arranged to have a larger projection angle θ. A projector unit may be used. When the projection angle θ is close to 0, the position of the corresponding bright spot is close to the focal point of the element lens (see FIG. 5), that is, the position of the optical center of the projector unit is the center of the unit figure corresponding to the focal point. This means that the point is close (see FIG. 6). In that case, the resolution of the stereoscopic image becomes high in the viewing zone close to the front surface of the lens array 14. As the peripheral viewing zone is farther from the front, a reduction in resolution is allowed and subjective quality is maintained. Therefore, an increase in cost can be suppressed by adding a projector unit having a low resolution in order to enlarge the viewing zone.

(Viewing zone)
Next, the viewing area of the stereoscopic image to be viewed will be described using the image display system 1 illustrated in FIG. 3 as an example. FIG. 8 is a diagram illustrating an example of the viewing zone. Projection light from each of the projector units 12 _{1 to} 12 ₃ is converged by the element lenses constituting the lens array 14, and bright spots l ₁ , l ₂ , and l ₃ are formed in the front focal plane 15. Bright spots l ₂ corresponds to the focal point of the element lens. The viewer visually recognizes the images represented by the light rays emitted from the bright spots l ₁ , l ₂ , and l ₃ . theta ₁ shows the viewing angle of the viewing area 1 image is viewed based on the projection light from the projector unit 12 _2. The viewing zone angle θ ₁ corresponds to the prospective angle of the element lens facing the bright spot l ₂ , that is, the angle formed by the direction from the bright spot l ₂ to the end point e ₂ and from the bright spot l ₂ to the end point e ₃ . Accordingly, the viewing zone angle θ ₁ is 2 · arctan (p / (2 · f)). θ ₂ represents the viewing zone angle of the viewing zone 2 where an image based on the projection light from each of the projector units 12 ₁ and 12 ₃ is visually recognized. The viewing zone angle θ ₂ corresponds to an angle formed by the direction from the bright spot l ₁ to the end point e _{1 and} the direction from the bright spot l ₃ to the end point e ₄ . Endpoint e _1, to the element lenses facing the bright spots l _1, is the end point of the element lenses adjacent the bright spots l ₂ in the direction of the bright points l _1. End point e _4, to the element lenses facing the bright spots l _3, an end point of the element lenses adjacent the bright spots l ₂ in the direction of the bright spots l _3. Accordingly, the viewing zone angle θ ₂ is 2 · arctan (p / f), which is larger than the viewing zone angle θ ₁ . The area filled with shading is the area 3 where the areas 1 and 2 overlap. The region 3 is a region where an image based on the projection light emitted from all of the _three bright spots l ₁ , l ₂ and l ₃ is observed. In other words, a high-resolution stereoscopic image is observed from the region 3 that is the front surface of the lens array 14.

In addition, since the viewing zone 2 is wider than the viewing zone 1, there is a diagonal region that does not include the viewing zone 1. In this oblique region, a stereoscopic image is visually recognized because images with different viewpoints of the projection light emitted from the two bright spots l ₁ and l ₃ are observed in a superimposed manner. That is, the resolution is lower than that of the stereoscopic image visually recognized in the area 3, but the area where the stereoscopic image is visually recognized is expanded to the area 2. In other words, according to the observation from the front, a stereoscopic image with a high resolution is visually recognized, and a peripheral region where the stereoscopic image is observed is added instead of a decrease in resolution. This indicates that the improvement of the resolution and the expansion of the viewing zone are compatible, and the stereoscopic effect is enhanced by the change in resolution due to motion parallax. This also realizes effective stereoscopic image presentation.

  As described above, the image display system 1 according to the present embodiment includes a plurality of projector units that project element images on the projection surface, and a projection that is arranged in parallel to the projection surface and is incident from the plurality of projector units. A light control lens 13 for converging light is provided. The image display system 1 includes a lens array 14 in which a plurality of element lenses that converge the projection light incident from the light control lens 13 are arranged on a plane perpendicular to each optical axis. The distance between the projection surface and the light control lens 13 is equal to the focal length F of the light control lens 13.

According to this arrangement, a plurality of projector units, e.g., projection light transmitted through the light control lens 13 from the projector unit 12 ₁ to 12 _N is incident on the element lenses as parallel light. On the front focal plane 15 where the focus of each element lens is distributed, the light rays forming part of the projection light from the plurality of projector units that have passed through the element lens are converged to form a bright spot. Projection light from each bright spot is emitted in a superimposed manner. By using a plurality of projector units, bright spots that act as pixels of an element image that forms a three-dimensional image are formed spatially denser than the focal point of the element lens. Therefore, the resolution of the stereoscopic image is efficiently improved without reducing the diameter of the projection element and element lens of the projector unit. For example, in the method described in Non-Patent Document 2, since the projection light projected on the lens array is not parallel light, the viewing zone where the stereoscopic image is observed is not necessarily formed in a desired direction or angle. On the other hand, in the image display system 1 according to the present embodiment, the position of the bright spot is determined according to the position of the projector unit. Therefore, a viewing zone in which a stereoscopic image is observed based on the arrangement of bright spots is formed in a desired direction and angle. Therefore, a three-dimensional image can be reproduced by creating an element image suitable for the specifications of the display device in advance for each projector unit and projecting the created element image from the corresponding projector unit.

In the image display system 1 according to the present embodiment, the plurality of projector units are arranged at regular intervals in at least one direction on the projection surface, for example, the x direction. Alternatively, the plurality of projector units are arranged at regular intervals for each direction in one direction on the projection surface and a direction intersecting the one direction, for example, the x direction and the direction intersecting the x direction at 45 degrees. . The interval is 1 / N of the distance obtained by multiplying the interval of the projector unit in each direction by the ratio of the focal length F of the light control lens to the focal length f of the element lens. However, N is an integer of 2 or more.
According to this configuration, a bright spot is formed at each equally divided point in the direction in which the projector unit is arranged on the front focal plane 15 where the distance in the direction in which the projection light from the lens array 14 travels is the focal length f. . Since the bright spot positions formed by the plurality of projection units are uniform, the resolution of the stereoscopic image is improved, and the projection is performed from different projection directions by the multiple projection units, and the stereoscopic image is observed to form the bright spot. The viewing area can be enlarged. For example, in the method described in Non-Patent Document 2, since the projection light projected on the lens array is not parallel light, the viewing zone where the integral stereoscopic image is observed is not necessarily formed in a desired direction or angle. On the other hand, in the image display system 1 according to the present embodiment, it is possible to improve both the resolution of the stereoscopic image and the expansion of the viewing area where the stereoscopic image is visually recognized.

In the image display system 1 according to the present embodiment, the optical axis directions of the plurality of projector units are parallel to the optical axis directions of the plurality of element lenses, respectively.
According to this configuration, the projection light representing the element image from each projector unit enters the optical axis direction of each element lens. Therefore, the entire element image from each projector unit is imaged without deviation on the rear focal plane 17 where the distance in the direction in which the projection light is received from the lens array 14 is the focal length f. Since the whole of the element images obtained by integrating the light rays coming from the projector units radiated from the bright spots are superposed on each other, the stereoscopic image is surely visually recognized. For example, in the method described in Non-Patent Document 2, since the plurality of projectors are arranged at different angles with respect to the surface of the lens array, projection light is projected from multiple directions. For this reason, the focus of each projection image may not be formed on a plane separated from the lens array by the focal length of each element lens. Therefore, a crosstalk in which a part of the projected light to be projected is projected onto an adjacent lens adjacent to the corresponding element lens may occur, and an unnecessary stereoscopic image may be formed. On the other hand, according to the image display system 1 according to the present embodiment, since crosstalk between element images is avoided, formation of an unnecessary stereoscopic image can be prevented.

In addition, the image display system 1 according to the present embodiment includes, for example, a stereoscopic video generation unit 10 as an image acquisition unit. The stereoscopic image generation unit 10 observes a subject common to the plurality of projection units from different viewpoints based on the positions of bright spots formed by the projection light incident from the plurality of projection units passing through the plurality of element lenses. The generated image is generated as an element image.
According to this configuration, it is possible to generate an element image representing a common subject observed from each viewpoint using the formed bright spot as a pixel. The position of each bright spot is uniquely determined based on the positions of the projection unit, the light control lens, and the element lens, and the focal lengths of the light control lens and the element lens. For example, in the method described in Non-Patent Document 2, since the positions of the bright spots are not uniform, it is necessary to actually measure display characteristics of an actual display device in advance and generate an element image according to the characteristics. It was. On the other hand, in the image display system 1 according to the present embodiment, it is possible to easily produce an element image to be projected on each projection unit without actually measuring display characteristics in advance. Therefore, the practicality of the image display system 1 that displays a stereoscopic image is improved.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

  For example, although the case where the image display system 1 described above includes the stereoscopic video generation unit 10 and the video recording / playback unit 11 as an image acquisition unit that acquires an element image is described as an example, the present invention is not limited thereto. In the image display system 1, the stereoscopic video generation unit 10 may be omitted. Further, the image acquisition unit may include a data input interface to which element image data indicating an element image is input from a device separate from the image display system 1.

  In addition, the lens array 14 described above is an example in which the center point of each element lens is arranged at each lattice point of a square lattice whose unit figure is a square. However, the present invention is not limited to this. . The center point of the element lens may be arranged at each lattice point of a lattice having parallel movement symmetry that is spatially repeated with a predetermined period. Examples of such a lattice include a rectangular lattice, a regular triangular lattice, and an isosceles triangular lattice. The optical centers of the plurality of projector units may be arranged in a unit graphic region having a center point at a position corresponding to the focal point of each element lens.

The stereoscopic video generation unit 10, the video recording / playback unit 11, the projector array 12, the light control lens 13, and the lens array 14 that constitute the image display system 1 may be separate from each other, or for each of a plurality of sets thereof. It may be integrated. For example, a set of the stereoscopic video generation unit 10 and the video recording / playback unit 11, a set of the plurality of projector units 12 _{1 to} 12 _N , and a set of the light control lens 13 and the lens array 14 are separate from each other. The set may be integrated.

Moreover, you may make it implement | achieve a part of image display system 1 mentioned above, for example, the three-dimensional video generation part 10 and the video recording / reproducing part 11, with a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. Here, the “computer system” is a computer system built in the stereoscopic video generation unit 10 and the video recording / playback unit 11 and includes hardware such as an OS and peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In this case, a volatile memory inside a computer system that serves as a server or a client may be included that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.
Moreover, you may implement | achieve part or all of the three-dimensional video generation part 10 and the video recording / reproducing part 11 in embodiment mentioned above as integrated circuits, such as LSI (Large Scale Integration). Each functional block of the stereoscopic video generation unit 10 and the video recording / playback unit 11 may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to the advancement of semiconductor technology, an integrated circuit based on the technology may be used.

DESCRIPTION OF SYMBOLS 1 ... Image display system, 10 ... Stereoscopic image production | generation part, 11 ... Video recording / reproducing part, 12 ... Projector array, 13 ... Light control lens, 14 ... Lens array

Claims (4)

A plurality of projecting units each projecting an element image on a projection surface;
A light control lens that is arranged in parallel with the projection surface and converges the projection light incident from the plurality of projection units;
A lens array in which a plurality of element lenses for converging projection light incident from the light control lens are arranged;
With
The distance between the projection surface and the light control lens is equal to the focal length of the light control lens. The plurality of projection units are arranged at a constant interval in at least one direction on the projection surface, or the plurality of projection units in one direction on the projection surface and the other direction intersecting the one direction, Arranged at regular intervals in each direction,
The distance is 1 / N of a distance obtained by multiplying the distance between adjacent element lenses by the ratio of the focal length of the light control lens to the focal length of the element lens (where N is an integer of 2 or more). The image display system according to claim 1, wherein: The image display system according to claim 1, wherein the optical axis directions of the plurality of projection units are parallel to the optical axis directions of the plurality of element lenses, respectively. Based on the position of a bright spot formed by the projection light incident from the plurality of projection units passing through the plurality of element lenses, images observed from different viewpoints of the subject common to the plurality of projection units The image display system according to any one of claims 1 to 3, further comprising an image acquisition unit that acquires the element image.

Images