JP2010068202A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that resolution is extremely deteriorated since only a part of a plane image corresponding to a viewing direction is viewed when viewing the plane image through a conventional lenticular lens. <P>SOLUTION: An image display device includes: an image surface; the first panel where the array of concave lenses is formed on one surface; and the second panel where the array of convex lenses are formed on one surface. The image surface, the first panel and the second panel are arranged in this order. The convex lenses and the concave lenses are facing each other. A stereoscopic image is displayed by arranging the first panel and the second panel at prescribed interval. At least the lens boundary parts of the first panel is made to substantially have contact with the lens boundary parts of the second panel, so as to display the plane image. Consequently, the image display device performs switching between the stereoscopic image and the plane image with high resolution. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device capable of switching between a planar image and a stereoscopic image.

  There are two types of stereoscopic image display devices that require glasses and those that do not. A stereoscopic image display device using a lenticular lens is known as a method that does not require glasses. FIG. 40 is a perspective view of a lenticular lens. In FIG. 40, reference numeral 4001 denotes a plurality of cylindrical lenses arranged in parallel.

  FIG. 41 is a cross-sectional view of a stereoscopic image display device using a lenticular lens. In FIG. 41, reference numeral 4101 denotes a lenticular lens, 4102 denotes an image display unit, and 4103 denotes a transparent panel. As the image display portion 4102, a liquid crystal layer, a plasma discharge portion, an organic EL layer, or the like is used. FIG. 41 shows a structure in which a lenticular lens 4101 is bonded to a general display composed of an image display unit 4102 and a transparent panel 4103. A multi-viewpoint image is displayed on the image display unit 4102, and the image is recognized three-dimensionally by being viewed with the left and right eyes through the lenticular lens 4101. If both the lenticular lens 4101 and the transparent panel 4103 are made of general glass or resin, their refractive indexes are comparable. In that case, the lenticular lens 4101 and the transparent panel 4103 are optically considered as one.

  One method for capturing a multi-viewpoint image is to capture an image of the subject from many directions. FIG. 42 is a configuration diagram for capturing a multi-viewpoint image. In FIG. 42, a subject 4201 is imaged using five cameras 4202 to 4206. The plurality of captured images have parallax with each other. FIG. 42 shows an example in which five cameras are used.

  FIG. 43 is a diagram showing a method for creating a multi-viewpoint image. 43, reference numerals 4302 to 4306 denote images captured by the cameras 4202 to 4206 in FIG. These captured images are divided into strip images and combined into one as shown in FIG. 43 to obtain a multi-viewpoint image 4301. In the multi-viewpoint image 4301, a portion corresponding to each cylindrical lens is a set of strip images corresponding to the captured images 4302 to 4306.

  44 and 45 are diagrams showing the principle of stereoscopic viewing using a lenticular lens. 44 and 45, 4401 is a cylindrical lens, and 4402 is an image plane. 44 and 45, the lenticular lens (4101 in FIG. 41) and the transparent panel (4103 in FIG. 41) are handled as a unit. The image 4403 displayed on the image plane 4402 is a set corresponding to one cylindrical lens of the multi-viewpoint image 4301 in FIG. In the example of FIGS. 44 and 45, a set of multi-viewpoint images 4403 is shown only on the image plane corresponding to one cylindrical lens. Actually, a multi-viewpoint image is displayed on an image plane corresponding to all cylindrical lenses. The light emitted from each point on the image plane becomes substantially parallel light by the cylindrical lens and enters the right eye or the left eye.

  As shown in FIG. 44, at the positions of the right eye 4404 and the left eye 4405, substantially right-light 4406 is incident on the right eye 4404, and substantially parallel light 4407 is incident on the left eye 4405. A stereoscopic image is recognized by looking at an image with parallax.

  When the position of the right eye 4404 and the left eye 4405 is changed as shown in FIG. 45 by moving the head position, substantially parallel light 4408 enters the right eye 4404 and substantially parallel to the left eye 4405. Light 4409 is incident to recognize the image three-dimensionally. Moving the head changes the three-dimensional direction, and things that were not visible in FIG. 44 can be seen in FIG. 45, increasing the sense of reality.

  In order to recognize a high-quality stereoscopic image, it is important that only an image near one point on the image plane is visible when the lenticular lens is viewed from one direction. If light from many points appears to be mixed, a plurality of images are mixed and the image quality deteriorates. In general, a set of multi-viewpoint images composed of a plurality of strip images as shown in FIG. 43 is displayed on the image plane corresponding to one cylindrical lens. In a set of multi-viewpoint images, adjacent strip images are images taken by adjacent cameras in FIG. 42, and have a strong correlation with each other. However, an adjacent set of multi-viewpoint images is displayed on the image plane corresponding to the adjacent cylindrical lens. In the vicinity of the boundary between adjacent cylindrical lenses, for example, images taken by the cameras 4202 and 4206 in FIG. 42 have a low correlation, and when they are mixed, image quality deteriorates. Therefore, the angle of light that exits from the image plane corresponding to the boundary point between adjacent cylindrical lenses and exits from the cylindrical lens with a relatively high intensity determines the viewing angle of the stereoscopic image.

  FIG. 46 shows light rays that determine the viewing angle. In FIG. 46, reference numeral 4601 denotes a cylindrical lens, 4602 denotes an image plane, and 4603 denotes a center line of the cylindrical lens. Light emitted from a point on the image plane corresponding to the boundary between adjacent cylindrical lenses is substantially parallel and has a relatively high intensity in the range between the light rays 4604 and 4605. The angle formed by these light rays with the lens center line 4603 determines the viewing angle.

  In the lenticular lenses as shown in FIGS. 44 and 45, the light emitted from different points on the image plane becomes substantially parallel light in different directions, so that the right eye and the left eye see different images and recognize a stereoscopic image. However, if the planar image is viewed through the lenticular lens, only a part of the planar image corresponding to the viewing direction is viewed, and the resolution deteriorates. In particular, small characters may become unreadable. Thus, an image display device that can switch between a planar image and a stereoscopic image has been proposed (see, for example, Patent Document 1).

  FIG. 47 is a cross-sectional view of a conventional image display device capable of switching between a planar image and a stereoscopic image. In FIG. 47, 4701 is a convex cylindrical lens array, 4702 is a concave cylindrical lens array, 4703 is an image display unit, and 4704 is a transparent panel. FIG. 47 shows a structure in which an array 4701 of convex cylindrical lenses is bonded to a general display including an image display portion 4703 and a transparent panel 4704. The convex cylindrical lens and the concave cylindrical lens are arranged so as to face each other.

  FIG. 48 is a cross-sectional view of a panel when a stereoscopic image is displayed using a conventional image display device, and FIG. 49 is a cross-sectional view of the panel when a flat image is displayed using a conventional image display device. is there. If the convex cylindrical lens 4701, the concave cylindrical lens 4702, and the transparent panel 4704 in FIG. 47 are made of general glass or resin, their refractive indexes are approximately the same. In that case, 4701 and 4704 can be handled optically as one. In FIGS. 48 and 49, 4801 is an integrated convex cylindrical lens, 4802 is a concave cylindrical lens, and 4803 is an image plane.

  In FIG. 48, the convex cylindrical lens panel 4801 and the concave cylindrical lens panel 4802 are arranged with an appropriate interval. A multi-viewpoint image is displayed on the image plane 4803. Light emitted from a point on the image plane 4803 is emitted from the convex cylindrical lens panel 4801 as focused light and is incident on the concave cylindrical lens panel 4802. The focused light becomes substantially parallel light by the concave cylindrical lens panel 4802 and is further emitted as substantially parallel light from the concave cylindrical lens panel 4802. A stereoscopic image can be recognized as in the conventional lenticular lens shown in FIGS.

In FIG. 49, the convex cylindrical lens panel 4801 and the concave cylindrical lens panel 4802 are disposed in close contact with each other. A general plane image is displayed on the image plane 4803. Light emitted from a point on the image plane 4803 passes through the convex cylindrical lens panel 4801 and the concave cylindrical lens panel 4802 with almost no change in the traveling direction thereof, and is emitted from the concave cylindrical lens panel 4802 as emitted light. The convex cylindrical lens panel 4801 and the concave cylindrical lens panel 4802 behave like a single transparent plate, and a general planar image can be recognized.
JP 2006-243732 A

  The conventional image display device (Patent Document 1) claims that the distance between the convex cylindrical lens panel and the concave cylindrical lens panel when displaying a stereoscopic image is preferably the extent of the lens focal length. However, this case has the following drawbacks. FIG. 50 shows rays of a conventional image display device. In FIG. 50, 5001 is a convex cylindrical lens panel, 5002 is a concave cylindrical lens panel, and 5003 is a light beam (solid line) to be observed. Reference numeral 5004 denotes a light ray (wave line) that refracts light from an image plane corresponding to an adjacent convex cylindrical lens and refracts on the adjacent convex cylindrical lens surface and enters the focused concave cylindrical lens surface. The light ray 5004 is mixed as substantially parallel light having an emission angle within the viewing angle, so that most of the light from different images enters the eye, and the quality of the stereoscopic image is deteriorated.

  The main cause of unwanted light (referred to as light leakage) as shown in FIG. 50 is that the distance between the convex cylindrical lens panel and the concave cylindrical lens panel is relatively large.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an image display device capable of switching between a high-quality planar image and a high-quality stereoscopic image.

  In order to solve the above-described conventional problems, an image display device of the present invention has a first panel having an image surface, a concave lens array formed on one surface, and a second panel formed with a convex lens array on one surface. The image plane, the first panel, and the second panel are arranged in this order, the convex lens and the concave lens face each other, and the first panel and the second panel are arranged at a predetermined interval to display a stereoscopic image. A planar image is displayed by disposing at least the lens boundary portion of the first panel and the lens boundary portion of the second panel in contact with each other. Thereby, an image display device capable of switching between a planar image and a stereoscopic image can be provided.

  Alternatively, the image display device of the present invention has an image plane, a second panel having a convex lens array formed on one side, a first panel having a concave lens array formed on one side, and an image plane and a second panel. Arranged in the order of the first panel, the convex lens and the concave lens are opposed to each other, and the second panel and the first panel are arranged at a predetermined interval to display a stereoscopic image, at least of the first panel. A planar image is displayed by arranging the lens boundary portion and the lens boundary portion of the second panel so as to contact each other, and the predetermined interval is not more than twice the radius of curvature near the lens center line of the convex lens. And Thereby, an image display device capable of switching between a planar image and a stereoscopic image can be provided.

  It is preferable that the concave lens and the convex lens are aspherical lenses. Even if the spherical lens is used, the planar image and the stereoscopic image can be switched. However, the viewing angle of the planar image and the stereoscopic image can be increased by using the aspherical lens.

  It is preferable that the radius of curvature near the lens center line of the convex lens is larger than the radius of curvature near the lens center line of the concave lens. Thereby, the quality of a planar image can be improved.

  It is preferable that the concave lens or the convex lens is an aspheric lens at the center of the lens and has a linear cross section at the periphery of the lens. As a result, the viewing angle of the stereoscopic image can be further increased.

  It is preferable that the shape of the aspheric lens is approximated by an ellipse, a parabola, a hyperbola, an even function, or a combination function thereof.

  In the image display device of the present invention, the first panel has a configuration in which an array of concave lenses having a refractive index n2 is formed on a first transparent plate having a refractive index n1, and the second panel has a second refractive index n1. A configuration in which an array of convex lenses having a refractive index n2 is formed on a transparent plate is preferable. Accordingly, it is possible to appropriately select a substance having a refractive index n2 and provide a high-quality planar image and stereoscopic image.

  The convex lens array or the concave lens array is preferably made of a resin in which fine particles are dispersed. Thereby, a high-quality stereoscopic image can be provided at low cost.

  The convex lens array or the concave lens array is preferably made of a transparent elastic body. Thereby, the viewing angle of a planar image and a three-dimensional image can be widened.

  The transparent elastic body is preferably silicone rubber.

  In the image display device of the present invention, it is preferable to form a conductive transparent thin film on at least one surface of the concave lens array or the convex lens array. Thereby, it is possible to prevent static electricity from being accumulated when the concave lens surface and the convex lens surface are separated or brought close to each other, and to switch between a stereoscopic image and a planar image stably.

  When displaying a three-dimensional image, it is preferable that a multi-viewpoint image is displayed on the image plane, and there is a portion where no image is displayed on both sides of the set of multi-viewpoint images. Thereby, the quality deterioration of a three-dimensional image can be prevented.

  When displaying a stereoscopic image, a multi-viewpoint image is displayed on the image plane, and the multi-viewpoint image is shifted outward from the center of each of the concave lens and the convex lens toward the outside of the first panel or the second panel. It is preferable to display it. Thereby, the viewing angle of a stereoscopic image can be expanded.

  According to the image display device of the present invention, it is possible to provide an image display device that can stably switch between a high-quality planar image and a high-quality stereoscopic image.

<Basic Configuration of Image Display Device of the Present Invention>
FIG. 1 is a cross-sectional view of an image display device capable of switching between a planar image and a stereoscopic image according to the present invention. In FIG. 1, 101 is a concave cylindrical lens array, 102 is a convex cylindrical lens array, 103 is an image display unit, and 104 is a transparent panel. FIG. 1 shows a structure in which a concave cylindrical lens array 101 is bonded to a general display including an image display unit 103 and a transparent panel 104. The concave cylindrical lens and the convex cylindrical lens are arranged to face each other.

  In the image display device of the present invention, the arrangement of the concave cylindrical lens array and the convex cylindrical lens array is opposite to that of the conventional image display device. It will be described later that the conventional problem is solved by this configuration.

  FIG. 2 is a cross-sectional view of a panel when a stereoscopic image is displayed using the image display device of the present invention, and FIG. 3 is a cross-sectional view of the panel when a flat image is displayed using the image display device of the present invention. FIG. When the concave cylindrical lens 101, the convex cylindrical lens 102, and the transparent panel 104 shown in FIG. 1 are made of general glass or resin, their refractive indexes are almost the same, and 101 and 104 can be treated as optically integrated. it can. 2 and 3, 201 is an integrated concave cylindrical lens, 202 is a convex cylindrical lens, and 203 is an image plane.

  In FIG. 2, the concave cylindrical lens panel 201 and the convex cylindrical lens panel 202 are disposed with an appropriate interval. A multi-viewpoint image is displayed on the image plane 203. Light emitted from a point on the image plane 203 is emitted from the concave cylindrical lens panel 201 as divergent light and enters the convex cylindrical lens panel 202. The divergent light becomes substantially parallel light by the convex cylindrical lens panel 202 and is further emitted from the convex cylindrical lens panel 202 as substantially parallel light. A stereoscopic image can be recognized in the same manner as a conventional lenticular lens (FIGS. 44 and 45).

  In FIG. 3, the concave cylindrical lens panel 201 and the convex cylindrical lens panel 202 are arranged in close contact or close to each other. A general plane image is displayed on the image plane 203. The light emitted from the point on the image plane 203 passes through the concave cylindrical lens panel 201 and the convex cylindrical lens panel 202 with almost no change in the traveling direction thereof, and is emitted from the convex cylindrical lens panel 202 as emitted light. The concave cylindrical lens panel 201 and the convex cylindrical lens panel 202 are combined to behave like a single transparent plate, and a general planar image can be recognized.

<Display of planar image>
As described above, when displaying a planar image, the concave cylindrical lens panel and the convex cylindrical lens panel are brought into close contact or close to each other. In general, the concave cylindrical lens panel and the convex cylindrical lens panel are manufactured by a method such as molding, and cannot be completely shaped as designed. Even if the concave cylindrical lens surface and the convex cylindrical lens surface are to be completely brought into close contact with each other, they are partially in contact with each other, and the other portions are in close proximity with a slight gap therebetween.

  FIG. 4 shows an example in which a concave cylindrical lens panel and a convex cylindrical lens panel are brought close to each other. It is a figure when a concave cylindrical lens surface and a convex cylindrical lens surface contact in the center part of a lens, but a slight space is made in a lens boundary.

  FIG. 5 is an enlarged view of the vicinity of the lens boundary in FIG. In FIG. 5, reference numeral 501 denotes a concave cylindrical lens surface, and 502 denotes a convex cylindrical lens surface. Since FIG. 5 is an enlarged view, the lens surface is almost linear. A light beam 503 and a light beam 504 indicate light that is refracted by the concave cylindrical lens surface 501 and the convex cylindrical lens surface 502. Since the concave cylindrical lens surface 501 and the convex cylindrical lens surface 502 are very close to each other, the light beam 503 is only slightly translated and does not deteriorate the image quality. However, the incident light beam 504 very close to the lens boundary of the concave cylindrical lens surface 501 changes its direction as shown in FIG. When the image display device is viewed from above, the image portion corresponding to the lens boundary cannot be seen.

  Therefore, when displaying a planar image, it is preferable that at least the lens boundary portion of the concave cylindrical lens and the lens boundary portion of the convex cylindrical lens are in contact with each other. As a result, there is no light whose direction changes greatly, such as the light beam 504.

  FIG. 6 shows an example of a concave cylindrical lens shape and a convex cylindrical lens shape suitable for bringing at least the lens boundary portion of the concave cylindrical lens into contact with the lens boundary portion of the convex cylindrical lens. In FIG. 6, reference numeral 601 denotes a concave cylindrical lens surface, 602 denotes a convex cylindrical lens surface, and 603 denotes a lens center line. The radius of curvature near the lens center line of the convex cylindrical lens is slightly larger than the radius of curvature near the lens center line of the concave cylindrical lens. If designed and manufactured as shown in FIG. 6, at least the lens boundary can be brought into contact. Although a slight space is formed at the center of the lens, the thickness (d) of the space is very small, the direction of the light beam is hardly changed, and the image quality is not deteriorated. It also prevents the center of the lens from contacting and creating a space at the lens boundary.

  FIG. 7 is an enlarged view of the vicinity of the lens boundary in FIG. In FIG. 7, reference numeral 701 denotes a concave cylindrical lens surface, and reference numeral 702 denotes a convex cylindrical lens surface. Since FIG. 7 is an enlarged view, the lens surface is almost linear. A light beam 703 indicates light refracted by the concave cylindrical lens surface 701 and the convex cylindrical lens surface 702. If the difference in gradient between the surface 701 and the surface 702 is made very small, the light beam 703 hardly changes its direction and does not deteriorate the image quality.

<Viewing angle of planar image>
As described above, the concave cylindrical lens surface and the convex cylindrical lens surface are not completely adhered. Therefore, the light from the image plane is totally reflected on the concave cylindrical lens surface and does not come out of the image display device depending on the emission angle. Therefore, it is necessary to first determine the viewing angle of the planar image and form a concave cylindrical lens shape so that light having an angle smaller than the viewing angle is not totally reflected.

FIG. 8 shows a case where a planar image is displayed. In FIG. 8, the same components as those in FIG. As described above, the concave cylindrical lens surface and the convex cylindrical lens surface are not completely adhered to each other, but details thereof are omitted in FIG. The light emitted from the image surface 203 at the exit angle θ exits from the image display device at the exit angle ν unless it is totally reflected by the concave cylindrical lens surface. When the refractive index of the concave cylindrical lens panel and the convex cylindrical lens panel is n, the relationship between ν and θ is expressed by (Equation 1).
(Expression 1) sin ν = n · sin θ

The viewing angle of the planar image corresponds to the maximum emission angle νmax, and the maximum emission angle θmax from the image plane is determined by (Equation 1). The concave cylindrical lens is formed in such a shape that the light having the emission angle θmax is not totally reflected on the surface. The total reflection on the surface of the concave cylindrical lens will be described with reference to FIG. In FIG. 9, reference numeral 901 denotes a concave cylindrical lens surface, 902 denotes light emitted from an image surface having an emission angle θmax, and 903 denotes a lens center line. Let η be the gradient angle of the lens shape at the boundary between adjacent concave cylindrical lenses. If the refractive index of the concave cylindrical lens portion is n2, the condition that the light from the image surface having the emission angle θmax is not totally reflected on the surface of the concave cylindrical lens is given by (Equation 2). Therefore, when the viewing angle νmax of the planar image is determined, the maximum emission angle θmax from the image surface is determined, and the maximum gradient angle η of the concave cylindrical lens shape is determined.
(Formula 2) sin (θmax + η) <(1 / n2)

<Viewing angle of stereoscopic images>
When displaying a stereoscopic image, a concave cylindrical lens panel and a convex cylindrical lens panel are arranged at an appropriate interval, and a multi-viewpoint image is displayed on the image plane. A viewing angle in displaying a stereoscopic image will be described with reference to FIG. In FIG. 10, reference numeral 1001 denotes a concave cylindrical lens surface, 1002 denotes a convex cylindrical lens surface, 1003 denotes an image plane, and 1004 denotes a lens center line. Reference numeral 1005 denotes a set of multi-viewpoint images (see FIG. 43). In FIG. 10, as in FIGS. 44 and 45, a set of multi-viewpoint images 1005 is shown only on the image plane corresponding to one cylindrical lens. Actually, a multi-viewpoint image is displayed on an image plane corresponding to all cylindrical lenses. In this case, as in FIG. 46, the viewing angle of the stereoscopic image exits from the image plane corresponding to the boundary between adjacent concave cylindrical lenses (the end of one set of multi-viewpoint images 1005) and exits from the convex cylindrical lens panel. Is the angle formed by the lens center line. Light in a range surrounded by the light ray 1006 and the light ray 1007 becomes substantially parallel, and they determine the viewing angle of the stereoscopic image. In order to increase the viewing angle, it is necessary to increase the cylindrical lens width.

  However, generally, if the lens width is increased, the gradient angle around the lens also increases. As described above, the viewing angle of the planar image is determined by the maximum gradient angle of the lens shape. Therefore, even if the lens width is increased, a lens shape in which the gradient angle of the lens shape is smaller than the maximum gradient angle is required. If the concave cylindrical lens is a spherical lens, the lens width having the maximum gradient angle that determines the viewing angle of the planar image is small. If an aspherical lens is used as the concave cylindrical lens, the viewing angle of the necessary planar image can be satisfied, and the viewing angle of the stereoscopic image can be increased by increasing the lens width. As such an aspheric lens shape, there are an ellipse, a parabola, a hyperbola, and an even function as described later.

  With reference to FIG. 11, a lens cross-sectional shape capable of increasing the lens width while maintaining the gradient angle of the lens shape within the maximum gradient angle will be described. In FIG. 11, reference numeral 1101 denotes a concave cylindrical lens, the lens central portion 1102 has an aspheric lens shape, and the lens peripheral portion 1103 has a linear cross section. If the straight portion 1103 is too wide, the function of the concave cylindrical lens is impaired. However, if the width of the straight portion is not large, the lens function is maintained and the lens width is increased.

  The convex cylindrical lens disposed opposite to the concave cylindrical lens in FIG. 11 has the following shape. First, as in FIG. 11, the central part is aspheric and the periphery is a straight line. In this case, the width of the central aspheric lens portion of the convex cylindrical lens is smaller than the width of the central aspheric lens portion of the concave cylindrical lens. Further, the radius of curvature in the vicinity of the lens center line of the convex cylindrical lens is substantially the same as the radius of curvature in the vicinity of the lens center line of the concave cylindrical lens.

  The second is an aspheric lens over the entire width of the convex cylindrical lens, but the radius of curvature near the lens center line of the convex cylindrical lens is larger than the radius of curvature near the lens center line of the concave cylindrical lens.

  The first or second case is not limited as long as at least the lens boundary portion of the concave cylindrical lens and the lens boundary portion of the convex cylindrical lens are in contact with each other or are almost in contact (substantially contact).

  Conventionally, as shown in FIGS. 44 and 45, one set of multi-viewpoint images is displayed in an image plane corresponding to one cylindrical lens. FIG. 12 shows a method for increasing the viewing angle of a stereoscopic image in the image display apparatus of the present invention. 12, 1201 is an image display device, 1202 is an image plane, 1203, 1204, and 1205 are sets of multi-viewpoint images displayed on the center, left end, and right end image plane 1202 of the image display device, respectively. Reference numerals 1206, 1207, and 1208 denote the positions of eyes that observe the image display device. As shown in FIG. 12, as the outer periphery of the image display device is displayed, the center of a set of multi-viewpoint images is shifted outward from the lens center line to display more oblique light. The viewing angle of the image increases.

<Resolution of stereoscopic images>
A three-dimensional image is an image viewed from a part of viewpoints among multi-viewpoint images corresponding to one lens. This is the same even when the center of the multi-viewpoint image is shifted from the lens center line as shown in FIG. Therefore, if the cylindrical lens width is increased, the viewing angle increases, but the resolution of the stereoscopic image decreases. It is necessary to increase the resolution and the viewing angle without increasing the cylindrical lens width.

  A method of increasing the viewing angle without increasing the width of the cylindrical lens is to increase the refractive index of the panel medium of the concave cylindrical lens and the panel medium of the convex cylindrical lens. As can be seen from FIG. 9, if the refractive index n2 of the concave cylindrical lens portion is increased, the total reflection angle (θmax + η in FIG. 9) decreases. In order to secure the viewing angle of the planar image, θmax cannot be reduced, and the angle η needs to be reduced, and the lens width is reduced. Even if the lens width is small, since the refractive index n2 of the concave cylindrical lens portion is large, the viewing angle of the stereoscopic image does not change much. That is, the viewing angle can be maintained, the lens width can be reduced, and the resolution of the stereoscopic image can be improved.

  Some high refractive index glasses have a refractive index greater than 1.8. However, a process such as molding is used for manufacturing the panel. Glass molding is expensive, and the glass may break. A resin having a low production cost and a high refractive index is desired. As such a resin, a “nanocomposite resin” in which fine particles having a high refractive index are dispersed is used. An ultraviolet curable resin is used as the base material resin, and fine particles of a dielectric such as titanium oxide, zirconium oxide, zinc oxide, or aluminum oxide having a diameter of 10 nanometers or less are used as the fine particles. A resin having a refractive index of about 1.7 can be synthesized by dispersing one kind or two or more kinds of dielectric fine particles.

  However, if fine particles are mixed in the resin, the transmittance decreases due to scattering by the fine particles. Therefore, when such a nanocomposite resin is used, a thin resin thickness is desired. FIG. 13 shows a configuration in which a high refractive index resin is used only for the cylindrical lens portion. In FIG. 13, 1301 and 1302 are transparent plates using a general resin, and 1303 is an image plane. Reference numeral 1304 denotes a lens center line, and reference numerals 1305 and 1306 denote lens portions using a high refractive index resin such as a nanocomposite resin. The thickness of the nanocomposite resin can be reduced to prevent a decrease in transmittance. That is, the resolution can be improved by maintaining the viewing angle of the stereoscopic image without increasing the refractive index of the lens portion and increasing the cylindrical lens width.

  If a high refractive index nanocomposite resin is used for the lens portion, there are several effects. The first is the improvement in resolution described above. Secondly, as will be described later, the interval between the concave cylindrical lens panel and the convex cylindrical lens panel can be reduced during stereoscopic image display. An actuator using electrostatic force, magnetic force or the like is used for the change in the interval. If the distance between the concave cylindrical lens panel and the convex cylindrical lens panel can be reduced, the load for driving the actuator can be reduced.

<Static charge prevention>
If the concave cylindrical lens panel and the convex cylindrical lens panel are placed close to each other and separated from each other at an appropriate interval, static electricity may be generated, and the proximity and separation between the concave cylindrical lens panel and the convex cylindrical lens panel may be reduced. It cannot be stabilized.

  Therefore, a conductive transparent thin film is provided on the surface of one or both of the concave cylindrical lens and the convex cylindrical lens. This conductive transparent thin film prevents static electricity from being accumulated, and can stably stabilize the concave cylindrical lens panel and the convex cylindrical lens panel in contact with or close to each other, or at an appropriate interval. FIG. 14 shows an example in which a conductive transparent thin film is provided on the surface of a concave cylindrical lens and the surface of a convex cylindrical lens. In FIG. 14, 1401 is a concave cylindrical lens panel, 1402 is a convex cylindrical lens panel, and 1403 is a conductive transparent thin film. Although details of the cylindrical lens shape are not shown in FIG. 14, the curvature near the lens center line as shown in FIG. 6 may be slightly different, or the lens center part as shown in FIG. The same applies to the case where is a linear shape. In FIG. 14, it is effective to provide a conductive transparent thin film on either the convex cylindrical lens surface or the concave cylindrical lens surface.

  As this conductive transparent thin film, ITO (Indium Tin Oxide) which is a transparent electrode of a liquid crystal display can be used. Although the refractive index of ITO is about 2, its thickness is very thin and almost uniform, the direction of light does not change before and after passing through the ITO, and it does not affect the viewing angle of planar images and stereoscopic images.

<Panel manufacturing method>
A panel manufacturing method will be described with reference to FIGS.
(1) First, a tool for manufacturing a panel mold is processed. The diamond is polished along the cylindrical lens shape. Since it is magnified using a microscope and polished while comparing with the target shape, it can be processed fairly accurately. Also, polishing is performed wider than the part actually required for processing. As shown in FIG. 11, if the central part is aspherical and the periphery is a straight line, the periphery of the cutting edge is also extended and polished. FIG. 15 shows a cutting tool edge 1501.

  (2) Next, the electroless nickel plated plate is cut using a diamond bit 1501. FIG. 16 shows the state of processing. A groove corresponding to the cylindrical lens is cut into the electroless nickel-plated plate 1502 with a diamond cutting tool, and then the cutting tool is moved by moving the cutting tool laterally by the pitch of the cylindrical lens. Accurate lateral transfer is important. Since it cannot cut deeply at once, cut several times every few microns. A mold can be made in this way.

  (3) A cylindrical lens panel is molded using the finished mold. This is shown in FIG. In FIG. 17, reference numeral 1503 denotes a mold, and 1504 denotes a convex cylindrical lens panel. Resin such as acrylic and polycarbonate is used for molding.

  (4) A method for manufacturing a concave cylindrical lens panel will be described. Using a nickel plating method, a stamper with the concavities and convexities reversed is manufactured from a die cut with a diamond tool, and this stamper is formed as a die in the same manner as in FIG. Manufacture lens panels. This is shown in FIG. In FIG. 18, reference numeral 1505 denotes a mold (stamper), and 1506 denotes a concave cylindrical lens panel.

  A method of manufacturing a concave lens array panel in which only the lens portion is made of a high refractive index resin as shown in FIG. 13 will be described with reference to FIG. In FIG. 19, 1901 is a transparent plate, and 1902 is a nanocomposite resin in which fine particles with a high refractive index are dispersed in an ultraviolet curable resin. Reference numeral 1903 denotes a mold in which a lens array similar to 1505 is formed. Reference numeral 1904 denotes an ultraviolet lamp, and 1905 denotes an ultraviolet ray. The transparent plate 1901 and the mold 1903 are opposed to each other, the nanocomposite resin 1902 is inserted between them, and the nanocomposite resin is cured by irradiating ultraviolet rays 1905 from the transparent plate 1901 side, and 1901 and 1902 are united. A panel on which a concave cylindrical lens array is formed is manufactured. The panel on which the convex cylindrical lens array is formed is also manufactured using a mold similar to 1503.

  The molding method as shown in FIG. 17 or FIG. 18 has a limit in manufacturing a thin panel. For example, when a panel having a side of about 10 cm is manufactured by an injection molding method, if the thickness of the panel is 0.4 mm or less, warpage or the like occurs and it becomes difficult. However, if the ultraviolet curing method of FIG. 19 is used, a relatively thin panel can be manufactured.

<Analysis of stereoscopic image display>
The image display device of the present invention is arranged in the order of an image plane, a concave cylindrical lens array, and a convex cylindrical lens array, and displays a stereoscopic image by separating the concave cylindrical lens array and the convex cylindrical lens array at an appropriate interval. At least the lens boundary portion of the concave cylindrical lens and the lens boundary portion of the convex cylindrical lens are brought into substantially contact with each other to display a planar image. First, if the viewing angle νmax of the planar image is set, the maximum emission angle θmax from the image plane is determined from FIG. 8 and (Equation 1). (Equation 1) also holds when the refractive indices of the lens portions are different as shown in FIG. Next, from FIG. 9 and (Equation 2), the maximum gradient angle η of the concave cylindrical lens shape is determined.

  If the concave cylindrical lens shape is determined, the convex cylindrical lens shape is determined. The convex cylindrical lens shape is shown in FIG. 6 or FIG. An appropriate distance between the concave cylindrical lens panel and the convex cylindrical lens panel must be determined when displaying a stereoscopic image. In addition, it is necessary to know the relationship between the concave cylindrical lens shape or the convex cylindrical lens shape and the viewing angle of the stereoscopic image.

  A high refractive index resin may be used only for the lens portion of the concave cylindrical lens or the convex cylindrical lens, and the radius of curvature near the lens center of the convex cylindrical lens may be larger than the radius of curvature near the lens center of the concave cylindrical lens. . In order to obtain an appropriate interval for displaying a stereoscopic image, including such a case, analysis is performed below with reference to FIG.

  In FIG. 20, the refractive index of the transparent plate 2001 and the transparent plate 2002 is n1, and the refractive index of the concave cylindrical lens portion 2005 and the convex cylindrical lens 2006 is n2. The space between the concave cylindrical lens and the convex cylindrical lens is air, and the refractive index is n = 1. The thickness of the transparent plate 2001 is C, and the thickness from the boundary between the transparent plate and the lens unit 2005 to the bottom of the concave cylindrical lens is H. The distance between the concave cylindrical lens and the convex cylindrical lens is D, the concave cylindrical lens shape is represented by F (X), and the convex cylindrical lens shape is represented by G (X) + D. By appropriately setting the functions F (X) and G (X), the shape of the concave cylindrical lens or the convex cylindrical lens can be expressed. The width of one cylindrical lens is W, and the radius of curvature in the vicinity of the lens center line 2004 is R. Reference numeral 2003 denotes an image plane.

  P1 is a point where light emitted from a point on the image plane 2003 at a distance δ from the lens center line 2004 is incident on the boundary between the transparent plate 2001 and the lens unit 2005, and P2 is a point where the light is incident on the concave cylindrical lens surface. To do. Next, let P3 be the point at which light refracted on the concave cylindrical lens surface is incident on the surface of the convex cylindrical lens, and let P4 be the point where the light is incident on the boundary between the lens unit 2006 and the transparent plate 2002. Thereafter, the light is emitted from the surface of the transparent plate 2002.

The angle θ of the light ray from the point on the image plane to the point P1 (Q, C) is obtained by (Equation 3), and the angle α refracted and emitted at the point P1 is obtained by (Equation 4). The light beam emitted from the point P1 is expressed by (Expression 5), and the X coordinate (X2) of the point P2 is obtained by solving the equation (Expression 6). The gradient of the lens curved surface at the point P2 is a differential coefficient of the function F (X) and is obtained by (Equation 7). The incident angle β to the lens curved surface [F (X)] is obtained by (Equation 8), and the exit angle γ is obtained by (Equation 9) from the law of refraction. A light ray traveling from the point P2 to the point P3 is expressed by (Equation 10). The X coordinate (X3) of the point P3 is obtained by solving the equation (Equation 11). The gradient of the lens curved surface at the point P3 is a differential coefficient of the function [G (X) + D] and is obtained by (Equation 12). The incident angle φ to the lens curved surface [G (X) + D] is obtained by (Equation 13), and the exit angle ψ is obtained by (Equation 14) from the law of refraction. The incident angle ξ to the point P4 is obtained by (Equation 15), and the exit angle ζ is obtained by (Equation 16) from the law of refraction. The exit angle ν from the panel is obtained by (Equation 17).
(Equation 3) tan θ = (δ−Q) / C
(Expression 4) n2 · sin α = n1 · sin θ
(Equation 5) YC =-(XQ) · cot α
(Equation 6) C− (X−Q) · cot α = F (X)
(Equation 7) tanκ = dF (X) / dX (X = X2)
(Equation 8) β = κ−α
(Equation 9) sinγ = n2 · sinβ
(Equation 10) YF (X2) =-(X-X2) .cot (κ-γ)
(Equation 11) F (X2) − (X−X2) · cot (κ−γ) = G (X) + D
(Equation 12) tanτ = dG (X) / dX (X = X3)
(Equation 13) φ = τ− (κ−γ)
(Expression 14) n2 · sinψ = sinφ
(Equation 15) ξ = τ−ψ
(Expression 16) n1 · sinζ = n2 · sinξ
(Expression 17) sinν = n1 · sinζ

  If a point on the image plane (distance δ from the lens center line 2004) and a refraction point P1 (distance X1 from the lens center line 2004) at the boundary between the transparent plate 2001 and the lens unit 2005 are given, (Equation 3) to (Equation 17). ), Θ, α, κ, β, γ, τ, φ, ψ, ξ, ζ, and ν are obtained in order, and the direction of light emitted from the transparent plate 2002 is obtained.

First, consider paraxial approximation with a small angle. In this paraxial approximation, the case where the concave cylindrical lens shape and the convex cylindrical lens shape are the same is considered for the sake of simplicity, and the functions F (X) and G (X) representing the lens shape are approximated by (Equation 18). Further, the curvature in the vicinity of the lens center line 2004 is (1 / R), and the differential coefficient representing the gradient is represented by (Equation 19). Here, σ has a value of (+1) or (−1) depending on the sign of the gradient. When the image surface 2003 side is a concave cylindrical lens as in the image display device of the present invention, when X is positive, the gradient near the lens center line is positive and σ = + 1.
(Equation 18) F (X) = G (X) = C + H
(Equation 19) dF (X) / dX = dG (X) / dX = σ (X / R)

In the paraxial approximation, (Equation 3) to (Equation 17) are approximated as (Equation 20) to (Equation 34), respectively.
(Equation 20) θ = (δ−Q) / C
(Expression 21) n2 · α = n1 · θ
(Equation 22) YC =-(XQ) / α
(Expression 23) C− (X2−Q) / α = C + H
(Equation 24) κ = (σ / R) · (X2)
(Equation 25) β = κ−α
(Equation 26) γ = n2 · β
(Expression 27) Y− (C + H) = − (X−X2) / (κ−γ)
(Expression 28) C + H− (X3−X2) / (κ−γ) = C + H + D
(Expression 29) τ = (σ / R) · (X3)
(Expression 30) φ = τ− (κ−γ)
(Equation 31) n2 · ψ = φ
(Expression 32) ξ = τ−ψ
(Expression 33) n1 · ζ = n2 · ξ
(Formula 34) ν = n1 · ζ

The lenticular lens effect, that is, the condition that light emitted from a point on the image plane (distance δ from the lens center line 2003) becomes substantially parallel light with a constant emission angle is that ν does not depend on θ. At least, the paraxial approximation needs to satisfy the lenticular effect well. In this case, the distance D between the two lens surfaces is given by (Equation 35) and (Equation 36).
(Equation 35) D = n1, n2, R / Δ
(Expression 36) Δ = (n2-1) [(n2-1) (n1 · H + n2 · C) / R
+ Σ · n1 · n2]

Here, the transparent plate and the cylindrical lens unit are the same medium (refractive index n). n1 = n2 = n, and L = C + H. Further, in the configuration of the concave cylindrical lens on the side close to the image surface as in the image display device of the present invention and the convex cylindrical lens on the light emission side, σ = + 1, and (Equation 35) and (Equation 36) are ( It is expressed as in Equation 37).
(Equation 37) D = nR / [(n-1) {(n-1) (L / R) + n}]

  Ideally, light emitted from different points on the image plane 2003 is emitted as parallel light having different emission angles from the convex cylindrical lens panel 2002. FIG. 21 shows the ideal behavior. The horizontal axis represents the position (X1) where light emitted from a point on the image plane enters the boundary between the transparent plate 2001 and the concave cylindrical lens portion 2005, and the vertical axis represents the emission angle (ν) from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light emitted from a point on the image plane corresponding to the adjacent cylindrical lens. For example, light emitted from a point on the image plane (δ = W / 4) becomes parallel light having a constant emission angle regardless of the position on the lens surface. In other words, if the image display device is viewed from the emission angle, only the image of the point (δ = W / 4) is viewed. In this way, the fact that light emitted from a point on the image plane becomes parallel light having a constant emission angle regardless of the incident position of the boundary is named the lenticular effect. In reality, such an ideal emission light cannot be obtained, and an embodiment in a realistic case will be described below.

<Embodiment 1>
Embodiment 1 of the image display apparatus of the present invention will be described. FIG. 22 shows the viewing angle of the first embodiment. In FIG. 22, reference numeral 2201 denotes a display unit of the image display device, and 2202, 2203, and 2204 denote eye positions to be observed. The width of the display unit 2201 of the image display device is 10 cm, and the observation distance is 40 cm. The viewing angle is set so that the image can be viewed normally even when the right eye or the left eye moves to the center of the image display device. In general, the distance between the right eye and the left eye is 6.5 cm. Accordingly, the angle at which the image display device 2201 is viewed from the eye 2203 is in the range of ± 0.12 radians, and the angle at which the image display device 2201 is viewed from the eyes 2202 or 2204 is from 0.04 radians to 0.29 radians. . An image display device having a viewing angle of ± 0.29 radians may be designed.

  In order to set the viewing angle νmax of the planar image to 0,29 radians, the maximum emission angle θmax from the image plane is 0.19 radians from FIG. 9 and (Equation 1). The maximum gradient angle (η) of the concave cylindrical lens shape is set so as to satisfy this maximum emission angle. This angle (η) depends on the refractive index n2 of the lens portion of the concave cylindrical lens.

  The viewing angle of the stereoscopic image must also be 0.29 radians or more. At that time, as shown in FIG. 12, the multi-viewpoint image displayed on the image plane shifts the center of the multi-viewpoint image to the outside of the lens center line toward the outside of the image display device.

Embodiment 1 of the image display device of the present invention has an aspheric lens shape in which the concave cylindrical lens and the convex cylindrical lens can be approximated well by a parabola. Further, as shown in FIG. 6, the radius of curvature (R ^* ) near the lens center of the convex cylindrical lens is slightly larger than the radius of curvature (R) near the lens center of the concave cylindrical lens (R ^* > R). Further, both the transparent plate and the lens portion are made of a general resin (refractive index is about 1.5).

The concave cylindrical lens shape and the convex cylindrical lens shape are represented by (Equation 38) and (Equation 39). The gradient of the lens shape is obtained by the differential coefficient of F (X) or G (X) and is expressed by (Equation 40) and (Equation 41). When the lens width is W and the outermost peripheral gradient angle (maximum gradient angle) of the concave cylindrical lens shape is η, the relationship of (Expression 42) is established. Further, in order for the lens boundary of the concave cylindrical lens and the lens boundary of the convex cylindrical lens to substantially contact each other, F (W / 2) = G (W / 2), and the relationship of (Equation 43) is established.
(Equation 38) F (X) = C + H + (1 / 2R) X ²
(Number 39) G (X) = C + H + d + (1 / 2R *) X 2
(Equation 40) dF (X) / dX = X / R
(Equation 41) dG (X) / dX = X / R ^*
(Expression 42) W = 2R · tan (η)
(Expression 43) R ^* = 1 / [(1 / R) − (8d / W ² )]

Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. If n1 = n2 = 1.5, C = 1.5, and H = 0, it is D = 1.33 that satisfies (Expression 37). From n2 = 1.5, θmax = 0.19, and (Expression 2), the maximum gradient angle (outermost peripheral gradient angle) of the concave cylindrical lens shape is η = 0.54. From Equation 42, W = 1.19. If d = 0.01, R ^* = 1.06 from (Equation 43). The simulation result is shown in FIG. (Equation 6) and (Equation 11) are quadratic equations of X, and a solution can be obtained algebraically. The horizontal axis is the position (X1) where the light emitted from the point on the image plane enters the virtual boundary surface between the transparent plate and the lens unit, and the vertical axis is the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  The following can be understood from FIG. Of the luminous flux from the lens center line (δ = 0) on the image plane toward the concave cylindrical lens, the angle is incident on the range (−0.2 <X1 <0.2) of the virtual boundary surface between the transparent plate and the lens unit. The light is emitted from the convex cylindrical lens panel as substantially parallel light having ν = 0. The light emitted from a point on the image plane (δ = W / 4) at a distance W / 4 from the lens center line is approximately an angle ν when entering the range of the virtual boundary plane (0.05 <X1 <0.25). When the light is emitted from the convex cylindrical lens panel as substantially parallel light having 0.09 radians and enters the virtual boundary surface in the range (−0.05 <X1 <0.05), the light becomes non-parallel light. When the light emitted from the point (δ = W / 2) on the image plane corresponding to the boundary between the cylindrical lenses adjacent to each other is incident on the range of the virtual boundary plane (0.2 <X1 <0.45), the angle is approximately ν. = 0.19 radians as substantially parallel light is emitted from the convex cylindrical lens panel and is incident on a virtual boundary surface in the range (0.1 <X1 <0.2), it becomes non-parallel light. When light incident from an image plane point (δ = 3W / 4) of an adjacent cylindrical lens is incident on a virtual boundary plane range (0.4 <X1 <0.6), the angle ν = 0.29 radians. When the light is emitted from the convex cylindrical lens panel as substantially parallel light and enters the virtual boundary surface in the range (0.3 <X1 <0.4), the light becomes non-parallel light.

  The light emitted from the point (δ = W / 4) on the image plane will be described with reference to FIG. In FIG. 24, 2401 is a first panel in which a transparent plate and a concave cylindrical lens array are integrated, 2402 is a second panel in which a transparent plate and a convex cylindrical lens array are integrated, 2403 is an image plane, and 2404 is a lens center line. It is. Reference numerals 2405 and 2406 denote virtual boundaries between the transparent plate and the lens unit. Both the transparent plate and the lens portion are formed of general resin, and this virtual boundary does not exist optically. The light in the range surrounded by the light ray 2407 (solid line) and the light ray 2408 (solid line) that emerges from the point (δ = W / 4) on the image plane is substantially parallel light having an angle of 0.09 radians from the second panel 2402. Emitted. There is also non-parallel light such as ray 2409 (dashed line).

  In order to recognize a high-quality stereoscopic image, it is important that only an image near one point on the image plane is visible when the panel is viewed from one direction. If light from many points appears to be mixed, a plurality of images are mixed and the image quality deteriorates. A case where the panel is viewed from an angle of 0.19 radians will be described with reference to FIG. In FIG. 25, the same components as those in FIG. Reference numeral 2410 denotes an eye having an angle of 0.19 radians. In FIG. 25, the eye 2410 is depicted as being near the panel, but is actually far in the direction of the arrow. As can be seen from FIG. 23, most of the light emitted from the point (δ = W / 2) on the image plane is substantially parallel light having an emission angle of 0.19 radians. These are lights in a region surrounded by the light ray 2411 (solid line) and the light ray 2412 (solid line) in FIG. 25, and the substantially parallel light can be seen from the eye 2410. On the other hand, part of the light emitted from other points on the image plane also has an emission angle of 0.19 radians. For example, light ray 2413 (dashed line) exits from a point where δ = 3W / 4 and is emitted with an exit angle of 0.19 radians. This light ray 2413 is generated when it enters a very narrow range of the virtual boundary surface 2405, and is very narrow compared with the range surrounded by the light ray 2411 and the light ray 2412, and its light quantity is small. That is, when the image display device is viewed from the direction of an angle of 0.19 radians, only the image near the point where δ = W / 4 is seen.

  23, when the change in the emission angle ν is large with respect to the horizontal axis (incident position X1 on the boundary surface), that is, when the gradient of the curve representing the emission angle is large, the light ray 2413 (dashed line) in FIG. In this way, the amount of light is small when viewed from a specific emission angle. If the image display device is viewed from a certain direction, the intensity of these non-parallel lights is small, and almost parallel lights are seen, and this does not cause a big problem in image quality degradation.

  A multi-viewpoint image is displayed on the image plane. In one set of multi-viewpoint images, adjacent strip images (FIG. 43) are images taken by adjacent cameras in FIG. 42, and are strongly correlated with each other. . However, the boundary between adjacent sets of multi-viewpoint images is, for example, an image captured by the cameras 4202 and 4206 in FIG. 42, and the correlation is low. When they are mixed, the image quality deteriorates. In Embodiment 1 of the image display device of the present invention, as shown in FIG. 12, the center of the multi-viewpoint image is shifted outward from the lens center line toward the outside of the image display device. Therefore, on the outside of the image display device, the end of the set of multi-viewpoint images of interest is displayed on the image plane corresponding to the adjacent concave cylindrical lens. The light emitted from the convex cylindrical lens that is focused from the end and has a relatively high intensity is also seen within the viewing angle.

  As can be seen from FIG. 23, the exit angle of the substantially parallel light emitted from the point (δ = 3W / 4) on the image plane corresponding to the adjacent cylindrical lens is 0.29 radians (17 degrees). This is the target value of the viewing angle of the stereoscopic image. That is, at the end of the image display device, as shown in FIG. 12, the center of the multi-viewpoint image is shifted from the lens center line of the concave cylindrical lens and displayed, and light from a point 3W / 4 away from the lens center line is displayed. Corresponds to the boundary of the viewing angle. This is shown in FIG. In FIG. 26, the same components as those in FIGS. 24 and 25 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 26, a light beam 2414 (solid line) and a light beam 2415 (solid line) are emitted light that determines the viewing angle. FIG. 26 also shows the light ray 2413 (broken line) in FIG. 25, but the amount of light is small as described above.

  The display position of the multi-viewpoint image on the image plane will be described with reference to FIGS. In FIGS. 27 and 28, 2701 is a concave cylindrical lens surface, and 2702 is an image surface. 2703 and 2704 are lens center lines, and 2705 is a set of multi-viewpoint images. 27 and 28 show an example in which one set of multi-viewpoint images is composed of 10 pixels. FIG. 27 shows the display position of the multi-viewpoint image 2705 in the center of the image display device, and corresponds to 1203 in FIG. FIG. 28 shows the display position of the multi-viewpoint image 2705 at the right end of the image display device, and corresponds to 1205 in FIG.

  As described above, the light emitted from the pixel located at a distance of 0.75 W from the lens center line corresponds to the boundary of the viewing angle. The width of one set of multi-viewpoint images is W. In FIG. 28, the distance to which the center of the multi-viewpoint image is shifted is 0.35W. In this case, light from the pixels (2706 and 2707) at both ends of the multi-viewpoint image 2705 is emitted outside the viewing angle.

  Images viewed from an outer viewpoint may be displayed on the pixels 2706 and 2707 at both ends of the multi-viewpoint image 2705. In this case, some image can be seen even when the image display device is observed from outside the viewing angle.

  Alternatively, no image is displayed on the pixel 2706 and the pixel 2707. That is, it may be displayed in black. In this case, the emission light of the set of multi-viewpoint images adjacent to the output light of the set of multi-viewpoint images of interest is prevented from being mixed as much as possible to prevent the quality of the image within the viewing angle from deteriorating.

  In Embodiment 1 of the present invention, when paying attention to one convex cylindrical lens, light emitted from a point on the image surface corresponding to the adjacent concave cylindrical lens is refracted by the lens surface of the adjacent concave cylindrical lens, and attention is paid. Leaks into the convex cylindrical lens. FIG. 29 shows the state of light leakage.

  In FIG. 29, the same components as those in FIGS. 24 to 26 are denoted by the same reference numerals and description thereof is omitted. With respect to the light ray 2414 (solid line) and the light ray 2415 (solid line), light emitted from a point (δ = 3W / 4) on the image plane corresponding to the adjacent concave cylindrical lens is emitted from the convex cylindrical lens panel 2402 as substantially parallel light. These light rays determine the viewing angle. On the other hand, the light ray 2416 (dashed line) exits from the point (δ = 3W / 4) on the image plane corresponding to the adjacent concave cylindrical lens, is refracted by the lens surface of the adjacent concave cylindrical lens, and is the convex of interest. Leaks into the cylindrical lens. However, the emission angle of the light ray 2416 from the convex cylindrical lens panel is larger than the emission angles of the light rays 2414 and 2415 and is outside the viewing angle.

  As described above, in Embodiment 1 of the present invention, there is light that exits from a point on the image surface corresponding to the adjacent concave cylindrical lens and is refracted and leaks at the adjacent concave cylindrical lens surface. Is emitted outside the viewing angle and does not affect the image within the viewing angle. The main reason is that, when displaying a stereoscopic image, the interval between the concave cylindrical lens panel and the convex cylindrical lens panel is not more than twice the radius of curvature near the lens center line and is relatively small. Thus, unlike the conventional image display device shown in FIG. 50, the quality of the stereoscopic image within the viewing angle is not deteriorated.

  The viewing angle (νmax) of the image display apparatus according to the first embodiment is ± 0.29 radians (± 17 degrees) for a planar image, and the viewing angle is ± 0.29 radians (± 17 degrees). A specific numerical example of the lens structure is shown for the case where 60 cylindrical lenses are used per inch. W = 423 μm. From W = 1.19, R = 356 μm. In this case, the thickness of the thinnest portion of the panel of the concave cylindrical lens is C = 534 μm, and it can be manufactured relatively easily even by using an injection molding method. The distance between the concave cylindrical lens for stereoscopic image display and the convex cylindrical lens is D = 473 μm, and the gap between the center of the concave cylindrical lens and the center of the convex cylindrical lens for planar image display is d = 3.6 μm. Further, as shown in FIGS. 27 and 28, if a set of multi-viewpoint images is composed of 10 pixels, the width of one pixel is 42 μm.

  A case will be described in which the number of cylindrical lenses per inch is increased to 100 to improve the resolution of a stereoscopic image. Regarding image display, the width of one pixel is reduced, or the number of pixels of one set of multi-viewpoint images is reduced. W = 254 μm. From W = 1.19, R = 213 μm. C = 320 μm, which is difficult to manufacture by the injection molding method. Further, D = 284 μm, so that the amount of movement of the panel is reduced, and the load on the actuator is reduced.

<Embodiment 2>
In Embodiment 2 of the image display device of the present invention, the concave cylindrical lens and the convex cylindrical lens have an aspherical lens shape in which the center portion of the lens can be approximated by a parabola as described with reference to FIG. Linear shape. The transparent plate and the lens part are both made of a general resin (refractive index 1.5) such as acrylic.

  In the second embodiment, the viewing angle is the same as that of FIG. 22, but the viewing angle νmax of the planar image is set slightly larger than that of the first embodiment and set to 0, 31 radians. 9 and (Equation 1), the maximum emission angle θmax from the image plane is 0.20 radians. The viewing angle of the stereoscopic image is desirably 0.31 radians or more. In the multi-viewpoint image displayed on the image plane, the center of the multi-viewpoint image is shifted to the outside of the lens center line toward the outside of the image display device as shown in FIG.

The concave cylindrical lens shape and the convex cylindrical lens shape are expressed by (Expression 43) to (Expression 48). Both the concave cylindrical lens shape and the convex cylindrical lens shape have the same radius of curvature R in the vicinity of the lens center line. Here, X _B and X _C represent a linear boundary with the parabolic lens, and W = 2AX _B, where W is the lens width. The gradient of the straight line around the concave cylindrical lens is η, but the gradient of the straight line around the convex cylindrical lens is (η−v). FIG. 30 shows the concave cylindrical lens shape and the convex cylindrical lens shape represented by (Equation 44) to (Equation 49).
(Equation 44) F (X) = C + H + (1 / 2R) X ²
(-X _B <X <X _B )
(Equation 45) F (X) = F (X _B ) + (X−X _B ) · tan η
(X _B <X <W / 2)
(Expression 46) F (X) = F (−X _B ) − (X + X _B ) · tan η
_{(-W / 2 <X <-X} B)
(Number 47) G (X) = C + H + d + (1 / 2R) X 2
(-X _C <X <X _C )
(Expression 48) G (X) = G (X _C ) + (X−X _C ) · tan (η−v)
(X _C <X <W / 2)
(Equation 49) G (X) = G (−X _B ) − (X + X _C ) · tan (η−v)
(-W / 2 <X <-X _C )

In the concave cylindrical lens, the parabolic outermost peripheral gradient and the linear portion have the same gradient. In the convex cylindrical lens, the gradient of the outermost peripheral part of the parabolic shape and the linear part is the same. Since the differential coefficient of the parabolic shape is expressed in the same manner as (Equation 40) and (Equation 41), the relationship of (Equation 50) and (Equation 51) is established.
(Number _{50) X B / R = tan} (η)
(Number _{51) X C / R = tan} (η-v)

Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. If n1 = n2 = 1.5, C = 1.5, and H = 0, it is D = 1.33 that satisfies (Expression 37). From n2 = 1.5, θmax = 0.20, and (Equation 2), η = 0.53. Further, v = 0.05, and the linear portion around the lens is reduced to A = 1.1. From (Equation 50) and (Equation 51), X _B = 0.58, X _C = 0.51, and W = 1.27. When displaying a planar image, the lens boundary of the concave cylindrical lens and the lens boundary of the convex cylindrical lens are substantially in contact with each other, and therefore d = 0.006. The simulation result is shown in FIG. (Equation 6) and (Equation 11) become a quadratic equation of X, and a solution can be obtained algebraically. The horizontal axis is the position (X1) where the light emitted from the point on the image plane enters the virtual boundary surface between the transparent plate and the lens unit, and the vertical axis is the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  From FIG. 31, it can be seen that the behavior of the light beam in the second embodiment is similar to that in the first embodiment (FIG. 23). The viewing angle is a little larger and is ± 0.31 radians (± 18 degrees). When the concave cylindrical lens shape and the convex cylindrical lens shape can be approximated by a parabola at the center, and the cross section of the peripheral part is a straight line and the lens width is slightly increased, the viewing angle of the stereoscopic image is slightly increased.

  Also in the second embodiment, there is light that exits from the point on the image surface corresponding to the adjacent concave cylindrical lens and is refracted and leaks at the adjacent concave cylindrical lens surface. Does not affect the image in the corner.

  The viewing angle (νmax) of the image display apparatus according to the second embodiment is ± 0.31 (± 18 degrees) for a planar image and ± 0.31 radians (± 18 degrees) for a stereoscopic image. is there. A specific numerical example of the lens structure is shown for the case where 60 cylindrical lenses are used per inch. W = 423 μm. From W = 1.27, R = 333 μm. In this case, the thickness of the thinnest portion of the concave cylindrical lens panel is C = 500 μm, and it can be manufactured relatively easily even by using an injection molding method. The distance between the concave cylindrical lens for stereoscopic image display and the convex cylindrical lens is D = 443 μm, and the gap between the center of the concave cylindrical lens for planar image display and the center of the convex cylindrical lens is d = 2.0 μm. Further, as shown in FIGS. 27 and 28, if a set of multi-viewpoint images is composed of 10 pixels, the width of one pixel is 42 μm.

  A case will be described in which the number of cylindrical lenses per inch is increased to 100 to improve the resolution of a stereoscopic image. Regarding image display, the width of one pixel is reduced, or the number of pixels of one set of multi-viewpoint images is reduced. W = 254 μm, and R = 1200 μm from W = 1.27. C = 300 μm, which is difficult to manufacture by the injection molding method. Further, D = 266 μm, so that the amount of movement of the panel is reduced and the load on the actuator is reduced.

<Embodiment 3>
In Embodiment 3 of the image display device of the present invention, the transparent plate is formed of a general resin (refractive index 1.5), and the lens part is formed of a high refractive index resin (for example, nanocomposite resin, refractive index 1.7). This is the case. Similarly to the second embodiment, the concave cylindrical lens shape and the convex cylindrical lens shape are aspherical lens shapes in which the center portion of the lens can be approximated by a parabola, and the cross section of the lens peripheral portion is a linear shape.

  In the third embodiment, the viewing angle is the same as in the description of FIG. 22, but the viewing angle νmax of the planar image is set slightly larger than in the second embodiment and set to ± 0, 32 radians. 9 and (Equation 1), the maximum emission angle θmax from the image plane is 0.21 radians. The viewing angle of the stereoscopic image is preferably 0.32 radians or more. Further, as shown in FIG. 12, the multi-viewpoint image displayed on the image plane shifts the center of the multi-viewpoint image to the outside of the lens center line toward the outside of the image display device.

The concave cylindrical lens shape and the convex cylindrical lens shape are expressed by (Expression 43) to (Expression 48). Both the concave cylindrical lens shape and the convex cylindrical lens shape have the same radius of curvature R in the vicinity of the lens center line. However, X _B , X _C , W, η, and (η−v) are optimized, and the numerical values are different from those in the second embodiment.

Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. If n1 = 1.5, n2 = 1.7, C = 1.5, and H = 0, it is D = 0.84 that satisfies (Expression 37). Further, as in the second embodiment, v = 0.05 and A = 1.1, and the linear portion around the lens is made small. From n2 = 1.7, θmax = 0.21, and (Equation 2), η = 0.44. From (Equation 50) and (Equation 51), X _B = 0.48, X _C = 0.42, and W = 1.05. When a planar image is displayed, d = 0.005 because the lens boundary of the concave cylindrical lens and the lens boundary of the convex cylindrical lens are substantially in contact with each other. The simulation result is shown in FIG. (Equation 6) and (Equation 11) are quadratic equations of X, and a solution can be obtained algebraically. The horizontal axis represents the position (X1) where light emitted from a point on the image plane enters the boundary surface between the transparent plate and the lens unit, and the vertical axis represents the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  From FIG. 32, it can be seen that the behavior of the light beam in the third embodiment is very similar to that in the second embodiment (FIG. 31). The viewing angle of the third embodiment is slightly larger than that of the second embodiment and is ± 0.32 radians (± 18 degrees). That is, by using a high refractive index resin only for the cylindrical lens portion, the viewing angle can be maintained by reducing the lens width, and the resolution of the stereoscopic image can be improved.

  Also in the third embodiment, there is light that exits from a point on the image surface corresponding to the adjacent concave cylindrical lens and is refracted and leaks at the adjacent concave cylindrical lens surface. Does not affect the image in the corner.

  The viewing angle (νmax) of the image display apparatus according to the third embodiment is ± 0.32 radians (± 18 degrees) for both planar images and stereoscopic images. A specific numerical example of the lens structure is shown for the case where 60 cylindrical lenses are used per inch. W = 423 μm. From W = 1.05, R = 403 μm. In this case, the thickness of the thinnest portion of the concave cylindrical lens panel is C = 604 μm. The distance between the concave cylindrical lens for stereoscopic image display and the convex cylindrical lens is D = 339 μm, and the gap between the center of the concave cylindrical lens and the center of the convex cylindrical lens for planar image display is almost the same as in the second embodiment, and d = 2.0 μm. . Also, if a set of multi-viewpoint images consists of 10 pixels, the width of one pixel is 42 μm.

  A case will be described in which the number of cylindrical lenses per inch is increased to 100 to improve the resolution of a stereoscopic image. Regarding image display, the width of one pixel is reduced, or the number of pixels of one set of multi-viewpoint images is reduced. W = 254 μm. From W = 1.05, R = 242 μm and C = 363 μm. Further, D = 203 μm, and the amount of movement of the panel is reduced, and the load on the actuator is reduced.

  In the third embodiment in which a high refractive index resin is used for the lens portion, the amount of movement (D) of the panel when switching between a stereoscopic image and a planar image can be made smaller than in the first and second embodiments, and the load on the actuator is reduced. it can.

  When the cylindrical lens width is reduced to improve the resolution, the thinnest part of the concave cylindrical lens panel becomes thin, and the injection molding method is not easy to manufacture. However, in Embodiment 3 in which a high refractive index resin is used for the lens portion, a panel can be manufactured by the method shown in FIG.

<Embodiment 4>
When displaying a planar image, it cannot be expected that the surface of the concave cylindrical lens and the surface of the convex cylindrical lens are completely in close contact with each other. Even if a part of the lens surface is in close contact, the other part has a small space. The reason is that the concave cylindrical lens panel and the convex cylindrical lens panel are made of general resin or nanocomposite resin, and the panel has high rigidity. Accordingly, at least the lens boundary portion of the concave cylindrical lens and the lens boundary portion of the convex cylindrical lens are in contact with each other. Further, the viewing angle νmax of the planar image is set, the maximum emission angle θmax from the image surface is obtained from (Equation 1), and the outermost peripheral gradient angle (maximum gradient angle) η of the concave cylindrical lens shape is obtained from (Equation 2). The width of the concave cylindrical lens is determined.

  If the lens portions of the concave cylindrical lens and the convex cylindrical lens are made of an elastic body instead of a rigid body, the above restriction is released. When a planar image is displayed, if pressure is applied to the concave cylindrical lens panel and the convex cylindrical lens panel, the lens surface is slightly deformed and can be brought into close contact with many parts. In this case, it is not necessary to limit the width of the concave cylindrical lens, and the viewing angle of the planar image is increased.

In Embodiment 4 of the image display device of the present invention, the lens portion of the concave cylindrical lens and the lens portion of the convex cylindrical lens are made of silicone rubber. Silicone rubber is an elastic body. Recently, a silicone rubber having a high refractive index has been developed. The refractive index of a general silicone rubber is about 1.4. Both the concave cylindrical lens shape and the convex cylindrical lens shape can be well approximated by the same parabola (Expression 52). Further, as shown in FIG. 12, in the multi-viewpoint image displayed on the image plane, the center of the multi-viewpoint image is shifted to the outside of the lens center line toward the outside of the image display device.
(Expression 52) F (X) = G (X) = C + H + (1 / 2R) X ²

  Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. The lens width is increased so that W = 3. The thinnest thickness of the concave cylindrical lens is also slightly increased to C = 2. If n1 = 1.5, n2 = 1.4, C = 2.0, and H = 0, it is D = 1.63 that satisfies (Expression 37). The simulation result is shown in FIG. (Equation 6) and (Equation 11) become a quadratic equation of X, and a solution can be obtained algebraically. The horizontal axis represents the position (X1) where light emitted from a point on the image plane enters the boundary surface between the transparent plate and the lens unit, and the vertical axis represents the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  From FIG. 33, the behavior of the light beam in the fourth embodiment is substantially parallel light in many parts of the emitted light, as in the first to third embodiments. As shown in FIG. 12, on the outside of the image display device, the center of the multi-viewpoint image displayed on the image plane is shifted to the outside of the lens center line, and the light emitted from the point (δ = 3W / 4) on the image plane is also viewed. Enter the corner. In FIG. 33, when light emitted from a point on the image surface (δ = 3W / 4) enters the boundary surface range (1.1 <X1 <1.6), the emission angle from the convex cylindrical lens panel The curve representing (ν) falls to the right. That is, the emitted light is slightly diffused light. However, the viewing angle is ± 0.5 or more.

  In the fourth embodiment, the interval between the concave cylindrical lens and the convex cylindrical lens when displaying a stereoscopic image is larger than those in the first to third embodiments. However, the interval is a radius of curvature near the lens center line of the concave cylindrical lens. The light that exits from the point on the image plane corresponding to the adjacent concave cylindrical lens and refracts and leaks at the adjacent concave cylindrical lens surface is emitted out of the viewing angle and falls within the viewing angle. Does not affect the image.

  The viewing angle of the image display apparatus according to the fourth embodiment can be increased for both planar images and stereoscopic images, and is ± 0.5 radians (± 29 degrees) or more. A specific numerical example of the lens structure is shown for the case where 60 cylindrical lenses are used per inch. W = 423 μm, and R = 141 μm smaller than W = 3.0. In this case, the thickness of the thinnest portion of the concave cylindrical lens panel is C = 282 μm. The interval between the concave cylindrical lens and the convex cylindrical lens for stereoscopic image display is D = 230 μm. Also, if a set of multi-viewpoint images consists of 10 pixels, the width of one pixel is 42 μm.

  A case will be described in which the number of cylindrical lenses per inch is increased to 100 to improve the resolution of a stereoscopic image. Regarding image display, the width of one pixel is reduced, or the number of pixels of one set of multi-viewpoint images is reduced. W = 254 μm. From W = 3.0, R = 85 μm and C = 169 μm. Further, D = 138 μm, and the amount of movement of the panel is reduced, and the load on the actuator is reduced.

<Embodiment 5>
In Embodiment 5 of the image display device of the present invention, the lens portion of the concave cylindrical lens and the lens portion of the convex cylindrical lens are made of elastic silicone rubber (refractive index is about 1.4). Further, the concave cylindrical lens shape and the convex cylindrical lens shape are both aspherical surfaces that can be well approximated by ellipses. The elliptic function is expressed by (Equation 53), and m is a coefficient that specifies the shape of the ellipse. In the multi-viewpoint image displayed on the image plane, the center of the multi-viewpoint image is shifted to the outside of the lens center line toward the outside of the image display device as shown in FIG.
(Formula 53) F (X) = G (X) = C + H + (mR) − [(mR) ² −m · X ² ] ^1/2

  In the elliptic function (Equation 53), if the coefficient m is set to infinity, it gradually approaches a parabola (Equation 52).

  Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. As in the fourth embodiment, the lens width is W = 3, and the thinnest thickness of the concave cylindrical lens is C = 2. If n1 = 1.5, n2 = 1.4, C = 2.0, and H = 0, it is D = 1.63 that satisfies (Expression 37). In (Equation 52), m = 3. The simulation result is shown in FIG. (Equation 6) and (Equation 11) become a quadratic equation of X, and a solution can be obtained algebraically. The horizontal axis represents the position (X1) where light emitted from a point on the image plane enters the boundary surface between the transparent plate and the lens unit, and the vertical axis represents the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  From FIG. 34, the light beam behavior of the fifth embodiment is very similar to that of the fourth embodiment, but the parallelism of the emitted light emitted from a point (δ = 3W / 4) on the image plane is improved. The viewing angle is ± 0.5 or more.

  Also in the fifth embodiment, the distance between the concave cylindrical lens and the convex cylindrical lens when displaying a stereoscopic image is not more than twice the radius of curvature in the vicinity of the lens center line of the concave cylindrical lens, and corresponds to the adjacent concave cylindrical lens. Light that exits from a point on the image plane and is refracted and leaked by the adjacent concave cylindrical lens surface is emitted outside the viewing angle and does not affect the image within the viewing angle.

  In the image display apparatus according to the fifth embodiment, the specific values of the viewing angle and the lens structure are the same as those in the fourth embodiment. By making the cylindrical lens shape an ellipse with a slightly larger gradient than the parabola, the parallelism of the emitted light is improved.

  In Embodiment 4 and Embodiment 5 in which silicone rubber is used for the lens portion, the amount of movement (D) of the panel when switching between a stereoscopic image and a planar image can be made smaller than in Embodiment 3, and the load on the actuator can be reduced.

  In the fourth and fifth embodiments, the thickness (C) of the thinnest portion of the concave cylindrical lens is very thin (282 μm or 138 μm) regardless of whether the number of cylindrical lenses per inch is 60 or 100. However, if silicone rubber is inserted between a transparent plate made of a general resin and a mold having a lens array (1503 in FIG. 17 and 1505 in FIG. 18) and solidified, a concave cylindrical lens panel and a convex lens are formed. Cylindrical lens panel can be manufactured

<Other lens shapes>
In the first to fourth embodiments, the cylindrical lens shape can be approximated by a parabola. In the fifth embodiment, the cylindrical lens shape can be approximated by an ellipse. In addition, there are cases where the lens shape can be well approximated by a hyperbola or even function. In the international patent application (PCT / JP2008 / 55053), the applicant of the present invention showed a viewing angle when the lens shape can be approximated by an ellipse, a hyperbola, and a quadratic even function.

The hyperbolic function is expressed by (Expression 54), and m is a coefficient that specifies the shape of the hyperbola. If the coefficient m is set to infinity, it will be asymptotic to a parabola (Equation 52).
(Formula 54) F (X) = G (X) = C + H− (mR) + [(mR) ² + m · X ² ] ^1/2

The fourth-order even function is expressed by (Equation 55), and (ρW) is the X coordinate of the inflection point of the fourth-order even function. If the coefficient ρ is set to infinity, asymptotic approach to the parabola (Equation 52) occurs. There is also an aspheric lens shape represented by an even function of 6th order or higher.
(Expression 55) F (X) = C + H + [1 / (2R)] · X ²
-[1 / {12R (ρW) ² }] · X ⁴

  Up to now, the aspherical lens shape has been shown to be able to approximate a parabola, an ellipse, a hyperbola, and an even function well, but is not limited thereto. For example, a combination of an ellipse and a hyperbola, or a combination of a hyperbola and a quartic even function may be used. Other aspherical lens shapes may be used as long as the viewing angle is large and the range in which substantially parallel light is obtained can be increased.

<Interpretation of conventional image display device>
In an image display device (Patent Document 1) capable of switching between a conventional stereoscopic image and a planar image, as shown in FIG. 47, a convex cylindrical lens panel is closer to the image plane and a light emitting side is a concave cylindrical lens panel. . Further, in this conventional image display apparatus, it is claimed that the distance between the convex cylindrical lens panel and the concave cylindrical lens panel is preferably about the focal length of these lenses. In this case, as shown in FIG. 50, light emitted from a point on the image plane corresponding to the adjacent convex cylindrical lens is refracted on the surface of the adjacent convex cylindrical lens and leaks to the concave cylindrical lens of interest. come. The leaked light has an emission angle that is substantially the same as the parallel light of the stereoscopic image being noticed, and degrades the image quality.

The focal length of the cylindrical lens will be described with reference to FIG. In FIG. 35, 3501 is the surface of the cylindrical lens, and 3502 is the center line of the cylindrical lens. A light ray 3503 exits from the point C on the lens center line and is refracted and emitted from the cylindrical lens surface 3501. The straight line OB is perpendicular to the surface of the cylindrical lens. If the point C on the lens center line is the focal point of the cylindrical lens, the light ray 3503 is parallel to the lens center line 3502, and the focal length f of the cylindrical lens 3501 corresponds to the distance between the point A and the point C. An incident angle α of the light beam 3503 to the lens surface 3501 is an angle formed by the line segment BO and the line segment BC, an angle formed by the line segment CA and the line segment CB is β, and an angle formed by the line segment OA and the line segment OB. If γ, (Equation 56) and (Equation 57) hold. Here, [OA] is the distance between point O and point A. If the refractive index of the cylindrical lens is n, (Equation 58) holds from the law of refraction.
(Formula 56) [OA] · tan γ = f · tan β
(Equation 57) γ = α + β
(Formula 58) n · sin α = sin γ

In FIG. 35, a case where the light beam 3503 is a paraxial approximation close to the lens center line 3502 will be described. In the paraxial approximation, the point O is the center of curvature near the lens center line, and the radius of curvature is R. That is, [OA] = R. (Formula 56) through (Formula 58) become (Formula 59) through (Formula 61). From (Equation 59) to (Equation 61), the focal length f is expressed by (Equation 62). When the lens medium is a general resin, the refractive index is n = 1.5, and the focal length f is (Expression 63).
(Equation 59) R · γ = f · β
(Equation 60) β = γ−α
(Equation 61) n · α = γ
(Equation 62) f = n · R / (n−1)
(Equation 63) f = 3R

  In the conventional image display device (Patent Document 1), the distance between the convex cylindrical lens panel and the concave cylindrical lens panel is preferably about the focal length of these lenses. When the lens medium is a general resin, the refractive index is about 1.5, which means that the distance between the two panels is preferably about three times the lens curvature radius. Compared with the first to fifth embodiments, the distance between the convex cylindrical lens panel and the concave cylindrical lens panel is considerably increased in the conventional image display apparatus. This is the main cause of light leakage that degrades the quality of a stereoscopic image, as shown in FIG.

  FIG. 36 shows a general configuration of the configuration of the convex cylindrical lens panel closer to the image plane and the light emission side of the concave cylindrical lens panel. In FIG. 36, 3601 and 3602 are transparent plates made of general resin, and 3603 is an image surface. Reference numeral 3604 denotes a lens center line, and reference numerals 3605 and 3606 denote lens portions formed of a high refractive index resin such as a nanocomposite resin.

  In the conventional image display device, a case where the lens portion of the convex cylindrical lens is made of a general resin having high rigidity will be described. When displaying a planar image, as in the first to third embodiments, the lens boundary of the convex cylindrical lens and the lens boundary of the concave cylindrical lens are substantially in contact with each other so that light rays within the viewing angle are not totally reflected. Limit the lens width. Further, it is preferable to prevent accumulation of static electricity by forming a conductive thin film on the convex cylindrical lens surface or the concave cylindrical lens surface.

  The configuration as shown in FIG. 36 can also be analyzed using FIG. In this case, the thickness from the boundary between the transparent plate and the lens portion to the top of the convex cylindrical lens is H. Whether the image surface side is a concave cylindrical lens or a convex cylindrical lens, the lens shape on the image surface 2003 side is represented as F (X), and the facing lens shape is represented as G (X) + D. By appropriately setting the functions F (X) and G (X), a concave cylindrical lens or a convex cylindrical lens can be expressed, and an aspherical lens shape can also be appropriately expressed.

Also in a conventional image display device, paraxial approximation can be obtained using (Equation 20) to (Equation 34). However, when X is positive, the gradient near the lens center line of the convex cylindrical lens is negative (σ = −1), and (Equation 35) and (Equation 36) are expressed as (Equation 64).
(Equation 64) D = nR / [(n-1) {(n-1) (L / R) -n}]

Also in the conventional image display device (Patent Document 1), a lens shape that can be approximated by a parabola is used. For simplicity, the concave cylindrical lens and the convex cylindrical lens have the same shape. The spherical functions F (X) and G (X) are expressed by (Equation 65).
(Expression 65) F (X) = G (X) = C + H− (1 / 2R) X ²

    Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. As the conventional image display device (Patent Document 1) claims, the distance between the convex cylindrical lens and the concave cylindrical lens is about the focal length of the lens. The conditions are n1 = n2 = 1.5, C + H = 5, and D = 3 from (Equation 64). As in the first embodiment, W = 1.19. The simulation result is shown in FIG. (Equation 6) and (Equation 11) become a quadratic equation of X, and a solution can be obtained algebraically. The horizontal axis is the position (X1) where the light emitted from the point on the image plane enters the virtual boundary surface between the transparent plate and the lens unit, and the vertical axis is the angle (ν) emitted from the convex cylindrical lens panel. Three cases of 0, W / 4, and W / 2 are shown as points on the image plane (distance δ from the lens center line 2004). The light from the point on the image plane (distance δ from the lens center line 2004) is 3W / 4 and W is not shown in FIG. 37 because it is emitted from the adjacent concave cylindrical lens.

  From FIG. 37, it can be seen that the angle of light emitted from the panel of the concave cylindrical lens is very large and the parallelism is high. However, as shown in FIG. 50, light exits from a point on the image plane corresponding to the adjacent convex cylindrical lens, is refracted on the surface of the adjacent convex cylindrical lens, and leaks to the concave cylindrical lens of interest ( There is much light leakage), and the quality of the stereoscopic image is significantly deteriorated.

<Embodiment 6>
Also in a conventional image display device, light leakage can be reduced if the distance between the convex cylindrical lens panel and the concave cylindrical lens panel can be reduced. The sixth embodiment is a case where the aspheric lens shape can be approximated by a parabola. For simplicity, the concave cylindrical lens and the convex cylindrical lens have the same shape, and the parabolic functions F (X) and G (X) are expressed by (Equation 65). Further, both the transparent plate and the lens portion are formed of a general resin (refractive index n = 1.5).

    Simulation is performed using FIG. 20 and (Equation 3) to (Equation 17). Here, the dimensions are normalized and represented as R = 1. If n1 = n2 = 1.5 and C + H = 12, then D = 0.67 from Equation 64. As in the first embodiment, W = 1.19. The simulation result is shown in FIG. (Equation 6) and (Equation 11) become a quadratic equation of X, and a solution can be obtained algebraically. The horizontal axis is the position (X1) where the light emitted from the point on the image plane enters the virtual boundary surface between the transparent plate and the lens unit, and the vertical axis is the angle (ν) emitted from the convex cylindrical lens panel. As the points on the image plane (distance δ from the lens center line 2004), five cases of 0, W / 4, W / 2, 3W / 4, and W are shown. δ = 3W / 4 and δ = W are light from a point on the image plane corresponding to the adjacent cylindrical lens.

  If the center of the multi-viewpoint image displayed on the image plane is shifted to the outside of the lens center line as shown in FIG. 12, the light emitted from the point (δ = 3W / 4) on the image plane also enters the viewing angle. . Although the parallelism of the emitted light is high, the viewing angle is as small as ± 0.15 radians (± 9 degrees). In this case, the distance between the convex cylindrical lens and the concave cylindrical lens is small and smaller than the radius of curvature in the vicinity of the lens center, and there is almost no light leakage as shown in FIG.

  In the sixth embodiment, the case where the lens shape can be approximated by a parabola is shown, but the present invention is not limited to this. The lens shape may be an ellipse, a parabola, a hyperbola, an even function, or a combination thereof.

Even in the configuration as shown in FIG. 36, if a high refractive index resin such as a nanocomposite resin is used only for the lens portion, the viewing angle can be maintained without increasing the lens width. In addition, the radius of curvature near the lens center of the convex cylindrical lens is made slightly larger than the radius of curvature near the lens center of the concave cylindrical lens, so that the quality of the planar image can be improved.
<Embodiment 7>

  In Embodiments 1 to 6 of the present invention, a cylindrical lens is used as a lens, but the same can be achieved by using a “fly eye lens” in which single lenses are arranged in a matrix in the vertical and horizontal directions. If the “fly eye lens” is used, the left and right eyes can recognize a stereoscopic image even if the image display device is rotated 90 degrees.

  A panel of such a “fly eye lens” is shown in FIG. In FIG. 39, 3901 is a single convex lens, and 3902 is a single convex lens array. A single-concave lens array having a shape opposite to that of this single-convex lens is also prepared, and the single-convex lens array panel or the single-concave lens array panel is moved as a set to move the single-convex lens array panel or the single-concave lens array panel. The display can be switched.

  Embodiments 1 to 7 disclosed above are merely examples of the present invention, and the present invention is not construed as being limited by these embodiments. The scope of the present invention is defined not only by the above-described embodiments but also by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  The image display device of the present invention has a function of switching between a high-quality stereoscopic image and a high-quality planar image, and is useful as a portable stereoscopic television. It can also be used for applications such as personal computer monitors and game consoles.

Sectional drawing of the image display apparatus of this invention. Sectional drawing of the panel in the case of displaying a stereo image in the image display apparatus of this invention. Sectional drawing of the panel in the case of displaying the plane image in the image display apparatus of this invention. The figure which shows the example of the panel space | interval in the case of displaying a plane image in the image display apparatus of this invention. The enlarged view of the lens boundary part in the case of displaying a plane image in the image display apparatus of this invention. The figure which shows the panel space | interval in the case of displaying a plane image in the image display apparatus of this invention. The enlarged view of the lens boundary part in the case of displaying a plane image in the image display apparatus of this invention. Explanatory drawing of the viewing angle of the plane image in the image display apparatus of this invention. Explanatory drawing of the total reflection of the concave cylindrical lens surface in the image display apparatus of this invention. Explanatory drawing of the viewing angle of a stereo image in the image display apparatus of this invention. The figure which shows the example of the concave cylindrical lens shape in the image display apparatus of this invention. The figure which shows the observer's eye position and the display position of a multi-viewpoint image in the image display apparatus of this invention. The block diagram which uses a different medium only for a lens part in the image display apparatus of this invention. The block diagram of the electroconductive transparent thin film in the image display apparatus of this invention. A cross-sectional view of a diamond tool for manufacturing a panel mold. The figure explaining the method of cutting the metal mold | die of a panel using a diamond bite. Explanatory drawing of the shaping | molding method of a convex lens panel. Explanatory drawing of the molding method of a concave lens panel. Explanatory drawing of panel manufacture using the ultraviolet curing method. The figure explaining analytically the principle of the three-dimensional image display in the image display apparatus of this invention. The figure which shows the ideal emitted light angle of a three-dimensional image display in the image display apparatus of this invention. The figure explaining the viewing angle of the image display apparatus in Embodiment 1 of this invention. The simulation result in Embodiment 1 of this invention. Explanatory drawing of the light which emerges from the point ((delta) = W / 4) of the image surface in Embodiment 1 of this invention. Explanatory drawing of the light emitted from the point ((delta) = W / 2) of the image surface in Embodiment 1 of this invention. Explanatory drawing of the light emitted from the point ((delta) = 3W / 4) of the image surface in Embodiment 1 of this invention. Explanatory drawing of the display position of the multiview image in the center of an image surface in Embodiment 1 of this invention. Explanatory drawing of the display position of the multiview image in the image surface right end in Embodiment 1 of this invention. Explanatory drawing of the light leakage in Embodiment 1 of this invention. Explanatory drawing of the lens shape in Embodiment 2 of this invention. The simulation result in Embodiment 2 of this invention. The simulation result in Embodiment 3 of this invention. The simulation result in Embodiment 4 of this invention. The simulation result in Embodiment 5 of this invention. Explanatory drawing of the focal distance of a convex lens. The block diagram which uses a different medium only for a lens part in the conventional image display apparatus. The simulation result in the conventional image display apparatus. The simulation result when the space | interval of a concave lens panel and a convex lens panel is small using the conventional image display apparatus. The perspective view of the fly's eye lens in Embodiment 7 of the present invention. The perspective view of a lenticular lens. Sectional drawing of the image display apparatus using a lenticular lens. Explanatory drawing of the imaging method of a multiview image. Explanatory drawing of the production method of a multiview image. The principle figure of the stereoscopic vision with respect to the position of the right and left eyes using a lenticular lens. The principle figure of the stereoscopic vision with respect to the changed position of the right and left eyes using a lenticular lens. Explanatory drawing of the viewing angle of a stereo image using a lenticular lens. Sectional drawing of the conventional image display apparatus. Sectional drawing of the panel in the case of displaying a stereo image in the conventional image display apparatus. Sectional drawing of the panel in the case of displaying the planar image in the conventional image display apparatus. Explanatory drawing of the substantially parallel light leakage in the conventional image display apparatus.

Explanation of symbols

101 Convex Cylindrical Lens Panel 102 Convex Cylindrical Lens Panel 103 Image Display Unit 104 Transparent Panel 201 Concave Cylindrical Lens Panel 202 Convex Cylindrical Lens Panel 203 Image Surface 601 Concave Cylindrical Lens Surface 602 Convex Cylindrical Lens Surface 603 Lens Center Line 901 Concave Cylindrical Lens Lens Shape at boundary 902 Ray having maximum emission angle from image plane 903 Lens center line 1101 Concave cylindrical lens 1102 Aspherical lens section 1103 Linear shape section 1201 Image display apparatus 1202 Image plane 1203 Multi-viewpoint image at the center of the image display apparatus 1204 Multi-viewpoint image at the left end of the image display device 1205 Multi-viewpoint image at the right end of the image display device 1206 Eye of the central observer 1207 View of the left end Eye 1208 of the rightmost observer 1301 Transparent plate 1302 Transparent plate 1303 Image plane 1304 Lens center line 1305 Lens portion 1306 Lens portion 1401 Concave cylindrical lens panel 1402 Convex cylindrical lens panel 1403 Conductive transparent thin film 1501 Diamond bite 1502 None Electrolytic nickel plated plate 1503 Mold 1504 Convex cylindrical lens panel 1505 Mold 1506 Concave cylindrical lens panel 1901 Transparent plate 1902 High refractive index resin 1903 Mold 1904 Ultraviolet lamp 1905 Ultraviolet 2001 Transparent plate 2002 Transparent plate 2003 Image plane 2004 Lens center line 2005 Lens unit 2006 Lens unit 2201 Display unit 2202 of the image display device 2202 Eye of the leftmost observer 2203 Eye of the observer at the center 204 Eye of observer at right end 2401 Transparent plate 2402 Transparent plate 2403 Image plane 2404 Lens center line 2405 Lens portion 2406 Lens portion 2407 substantially parallel light 2408 substantially parallel light 2409 non-parallel light 2410 observer's eye 2411 substantially parallel light 2412 substantially parallel Light 2413 non-parallel light 2414 substantially parallel light 2415 substantially parallel light 2416 light leakage 2701 concave cylindrical lens surface 2702 image surface 2703 lens center line 2704 lens center line 2705 multi-view image 2706 end pixel of one set of multi-view image 2707 one set Edge pixels of multi-viewpoint image 3601 Transparent plate 3602 Transparent plate 3603 Image plane 3604 Lens center line 3605 Lens portion 3606 Lens portion 3901 Single lens 3902 Fly's eye lens 4001 Cylindrical lens 4101 Ren Curular lens 4102 Image display unit 4103 Transparent panel 4201 Subject 4202 Camera 4203 Camera 4204 Camera 4205 Camera 4206 Camera 4301 Composite multi-viewpoint image 4302 Image captured by the camera 4202 4303 Image captured by the camera 4203 4304 Image captured by the camera 4204 4305 Camera Image captured by 4205 4306 Image captured by camera 4206 4401 Cylindrical lens 4402 Image plane 4403 Multi-viewpoint image 4404 Right eye 4405 Left eye 4406 Substantially parallel light 4407 Substantially parallel light 4408 Substantially parallel light 4409 Substantially parallel light 4701 Convex cylindrical lens panel 4702 Concave cylindrical lens panel 4703 Image display unit 4704 Transparent panel 4801 Convex cylindrical lens panel Nell 4802 Concave cylindrical lens panel 4803 Image surface 5001 Convex cylindrical lens panel 5002 Concave cylindrical lens panel 5003 Substantially parallel light 5004 Substantially parallel light leakage

Claims (15)

A first panel having an image surface, having a concave lens array on one side, and a second panel having a convex lens array on one side, arranged in the order of the image surface, the first panel, and the second panel; The convex lens and the concave lens face each other, and the first panel and the second panel are arranged at a predetermined interval to display a stereoscopic image, and at least the lens boundary portion of the first panel and the lens of the second panel An image display device characterized in that a planar image is displayed by arranging the boundary portions so as to be substantially in contact with each other. A first panel having an image surface, having a convex lens array on one side, a first panel having a concave lens array on one side, and arranging the image surface, the second panel, and the first panel in this order; The convex lens and the concave lens face each other, and the second panel and the first panel are arranged at a predetermined interval to display a stereoscopic image, and at least the lens boundary portion of the first panel and the lens of the second panel An image display device characterized in that a plane image is displayed by arranging the boundary portions so as to substantially contact each other, and the predetermined interval is not more than twice a radius of curvature in the vicinity of the lens center line of the convex lens. The image display device according to claim 1, wherein the concave lens and the convex lens are aspherical lenses. The image display device according to claim 1, wherein a radius of curvature in the vicinity of a lens center line of the convex lens is larger than a radius of curvature in the vicinity of a lens center line of the concave lens. 3. The image display device according to claim 1, wherein the concave lens or the convex lens is an aspheric lens at a lens central portion, and a cross section of a lens peripheral portion is a linear shape. 6. The image display device according to claim 3, wherein the shape of the aspheric lens is approximated by an ellipse, a parabola, a hyperbola, an even function, or a combination function thereof. The first panel has a configuration in which a concave lens array having a refractive index n2 is formed on a first transparent plate having a refractive index n1, and the second panel is a convex lens having a refractive index n2 on a second transparent plate having a refractive index n1. The image display device according to claim 1, wherein the image display device has a configuration in which an array is formed. The image display device according to claim 7, wherein the convex lens array or the concave lens array is made of a resin in which fine particles are dispersed. The image display device according to claim 7, wherein the convex lens array or the concave lens array is made of a transparent elastic body. The image display device according to claim 9, wherein the transparent elastic body is silicone rubber. The image display apparatus according to claim 1, wherein a conductive transparent thin film is formed on at least one surface of the concave lens array or the convex lens array. 3. The image display device according to claim 1, wherein when displaying a stereoscopic image, the image display apparatus includes a portion that displays a multi-viewpoint image on the image plane and does not display an image on both sides of the set of the multi-viewpoint images. When displaying a stereoscopic image, a multi-viewpoint image is displayed on the image plane, and the multi-viewpoint image is shifted outward from the center of each of the concave lens and the convex lens toward the outside of the first panel or the second panel. The image display device according to claim 1, wherein the image display device displays the image as a display. The image display device according to claim 1, wherein the concave lens and the convex lens are cylindrical lenses. The image display device according to claim 1, wherein the concave lens and the convex lens are single lenses.

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