JP2006030229A - Curved surface lens and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curved surface lens for use in a stereoscopic display device showing a two-dimensional image as a stereoscopic image giving a feeling of depth, which realizes a larger-screen stereoscopic display device with a relatively thin shape. <P>SOLUTION: The curved surface lens has a structure wherein microlens array surface C ( included in a portion 22) having small convex lenses and small concave lenses having small spread areas is interposed between two Fresnel lens surfaces A and B having large spread areas, and a boundary surface where solid members different by refractive indexes are brought into contact with each other is taken as the microlens array surface C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a curved lens and a display device. More specifically, the present invention relates to a curved lens in which a plurality of lens surfaces are combined to make a two-dimensional image look like a three-dimensional image, and a display device using the curved lens.

  Several methods have already been presented as methods for viewing a two-dimensional image such as a photograph or printed matter as a three-dimensional image. (For example, see Non-Patent Document 1)

  As a typical example, a photograph (or a drawn image) obtained by photographing a target object from two different directions is individually viewed with the left eye and the right eye, and a stereoscopic effect is sensed by binocular parallax. In this method, it is necessary to look into a device made so that different images can be seen by the left and right eyes, and it is not suitable as a normal signboard or guide board.

  As another example, a method of viewing a two-dimensional image as a three-dimensional image using a lenticular plate is well known. This is a strip of 2D images of continuous symbols viewed from a number of different directions on the back, which is the focal plane of a lenticular plate in which a number of vertically long (semi-cylindrical) lenses are arranged in the horizontal direction. Cut the strips into (long and narrow rectangles), dispose the discontinuous pattern display image in which the strips of symbols in different directions are arranged in order in the horizontal direction, and place the right through the small cylindrical lens that forms the lenticular plate. As a 3D image, the design seen by the eyes or the left eye is a collection of strips of the design seen from a specific direction, and the design seen by the right and left eyes is a design seen from different directions. It is a method of recognition.

  The display image in this method is not a single continuous image, but a special image that is a discontinuous vertical stripe in which strip-shaped symbols that are independent from each other are continuously connected. This strip-shaped pattern should be placed in a position that is very close to the focal plane of the lenticular plate in the depth direction, and the small cylindrical surface that constitutes the lenticular plate in the left-right direction. Strict positional accuracy is required due to the positional relationship with the lens. In this way, there is a disadvantage that it is necessary to create a special image, and that a severe condition is imposed on the alignment between the image and the lens, so that it is expensive and is not easy to replace. Furthermore, it is necessary to distinguish the strip-shaped symbols that are visible to the left eye from the strip-shaped symbols that are visible to the right eye, and the distance from the display device of the observer, the viewing angle for viewing the display device, etc. are limited. There are drawbacks.

  In addition, there is the following description that is rich in suggestions about stereoscopic images. “If you look at a picture with a single eye through a magnifying glass, you will see an unexpectedly strong three-dimensional effect in the image of one eye in an appropriate positional relationship.” The reason for this is outlined in the book as follows: Has been. “Because it is a single eye,“ binocular parallax ”and“ convergence ”of the eye do not function, but only the eye adjustment function is effective, and as a result of moving the virtual image from the position where the actual image is located, Loses the clue of whether or not it is solid, and the solid and the brain judge based on experience. That is, it is described that this is a phenomenon in which the brain senses three-dimensionally due to the illusion when the image can be moved from the actual image position. (See Non-Patent Document 1)

  The display image viewed through the celestial glasses is a two-dimensional image such as a photograph that can be normally viewed in which the entire image is continuous as one pattern. They are so-called photographs and pictures. The inventor of the present invention has proposed a stereoscopic display device that utilizes the phenomenon of stereoscopic effect due to the eye adjustment function that appears when viewing with one eye through the magnifying glass. Although a detailed description thereof is omitted, the outline is as follows. (For example, see Patent Document 1)

  When viewed through a microlens array with small lenses arranged in one plane, placed in front of the display image, the images created by the individual small lenses are combined into new pixels that are separated from the position of the display image. As a result of forming the whole image, a three-dimensional display without distortion in the horizontal and vertical directions is performed. The display image used here is a two-dimensional display image made up of continuous symbols such as photographs that are commonly seen. That is, the two-dimensional display image viewed from one point is not created by combining the two-dimensional display images viewed from two points. Hereinafter, unless otherwise specified, the term “display image” or “two-dimensional display image” refers to a two-dimensional display image having a continuous pattern viewed from one point such as a photograph that is generally seen.

  The above-described three-dimensional display by the microlens array is based on the principle of an eye adjustment function that appears when viewing with one eye through a magnifying glass.

  However, an image viewed with both the left and right eyes via a magnifying glass, that is, a lens, has a stronger stereoscopic effect than an image viewed with one eye, and the appearance is greatly related to the configuration of the curved lens used. A new stereoscopic display device using such a curved lens has been presented by the inventors of the present invention. Although these details are omitted, the outline of the part related to the present invention is as follows. (See Patent Document 2)

  When viewed through a curved lens placed in front of the two-dimensional display image, the light emitted from one point of the display image reaches the left and right eyes through different locations on the curved lens. Differences occur in the images formed on the retina, and the effect of “binocular parallax” acts to create a stereoscopic effect. The three-dimensional effect that appears here appears even when the convex surface or concave surface constituting the lens surface of the curved lens is a curved surface having a sufficiently wide extension, or when the concave surface and the convex surface repeat at a relatively narrow interval. In addition, when a curved lens surface with a sufficiently wide spread and a curved lens surface with a small concave surface and a small convex surface repeated at relatively narrow intervals are stacked in multiple layers, both lens curved surfaces act synergistically. It has been proposed that a stronger three-dimensional effect is developed. Furthermore, it has been proposed to reduce the thickness of a curved lens by making a curved lens surface having a sufficiently wide spread into a lens surface of a Frennel lens type.

JP 2001-42805 A (paragraphs 0053 to 0122, FIGS. 1 to 7 and the like) International Publication No. WO 2004/011966 A1 (pages 18 to 55, FIGS. 1 to 16, etc.) “Three Dimensional Image Engineering” written by Takayoshi Ohkoshi, published by Asakura Shoten, first published on July 10, 1991 (9 pages, etc.)

  The present invention is an invention described in Patent Document 2, which has a structure in which a curved lens surface having a sufficiently wide spread, a small concave surface having a small area at a relatively narrow interval, and a lens curved surface in which the small convex surface repeats in multiple layers. The main purpose is to further improve the performance as a curved lens and a display device based on the curved lens. That is, in a stereoscopic display device using a curved lens composed of a microlens array surface in which a Flennel lens surface, a convex lens, and a concave lens are alternately arranged, the enhancement of the stereoscopic effect, the enlargement of the screen, and the thinness of the device The present invention provides a curved lens that can be made into a lens.

A first object of the present invention is to provide a curved lens that can be applied to a wider display screen, and to realize a large-screen stereoscopic display device with a relatively thin shape.
The second object is to provide a curved lens capable of reducing the sense of incongruity caused by the distortion of the generated image, and realizing a display device with a strong stereoscopic effect and good image quality.
A third object is to reduce moiré fringes caused by a Frennel lens curved surface or a lens curved surface in which a small concave surface and a small convex surface are repeated at narrow intervals.

  In order to solve the above-described problem, the curved lens according to claim 1 is at least two or more having a single smooth convex surface or a single smooth concave surface as a mother curved surface as shown in FIGS. Small convex lenses i1 to i4 and small concave lenses i1 'to i4 having a sufficiently small area with respect to the areas of the first and second Frennel lens surfaces A and B of the two or more Frennel lens surfaces. And a microlens array surface C formed by alternately arranging “and”.

  Here, a single smooth convex surface is a surface without a discontinuous joint where the tangents of the curved surface of the lens consisting only of the convex surface do not coincide, and a surface whose curvature varies depending on the location is also regarded as a single convex surface. A single smooth concave surface is a surface without a discontinuous joint where the tangents of the curved surface of the lens consisting only of the concave surface do not coincide with each other, and a surface whose curvature changes depending on the location is also regarded as a single concave surface. A sufficiently small area means that the range of image distortion caused by individual lenslets is sufficiently small relative to the range of image distortion caused by a relatively wide Frennel lens surface, and it can be ignored that each other's distortion affects each other. The area of the small lens is as small as possible. For example, the area ratio is preferably 1/100 or less, and more preferably a minute area of a pixel that can be regarded as one point on the display image. The alternating arrangement may be arranged alternately in only one direction, and the convex surface or the concave surface may be smoothly connected in a direction orthogonal thereto. Also, when convex portions and concave portions are alternately arranged in two orthogonal directions, or irregularly shaped convex surfaces and concave surfaces, the convex surface is adjacent to the concave surface, and the concave surface is adjacent to the convex surface alternately and irregularly. In some cases. In some cases, convex portions or concave portions are alternately arranged at adjacent lattice points of the honeycomb structure. In addition, when a plane is interposed in a very narrow region between the convex surface and the concave surface, and both curved surfaces are smoothly connected, it is regarded as an alternating arrangement of the convex surface and the concave surface.

  With this configuration, since there are at least two Frennel lens surfaces, the curvature of the generating surface of each Frennel lens surface can be reduced compared with the case where the Frennel lens surface is single, and the wider A curved lens having an effective area can be obtained. That is, by using two Frennel lens surfaces, it is possible to obtain the most efficient configuration capable of reducing the curvature of the mother curved surface comprehensively. In addition, even if the generating surface of the two Frennel lens surfaces changes in any direction, the three-dimensional effect of both Frennel lens surfaces can be emphasized with each other. Furthermore, by using a microlens array surface on which small convex lenses and small concave lenses with a small area are used in combination, the three-dimensional effect is further enhanced and the area of the small convex lens and the small concave lens is small. The effects of distortion caused by the lens surface and the microlens array surface do not intensify each other.

  In addition, when the microlens array surface is a heterogeneous alternating arrangement in which convex lenses and concave lenses are alternately arranged, a three-dimensional appearance is exhibited compared to a case of small convex lenses or a homogeneous continuous arrangement in which small concave lenses are continuously arranged. The power becomes stronger. The reason for the strong three-dimensional effect in the case of heterogeneous alternating arrangement is that the difference between the images of both eyes can be increased because the concave and convex lines are arranged, and the curved surface changes less rapidly than in the case of the homogeneous continuous arrangement. It can also be interpreted that the local distortion is small and the image quality is good.

In the invention according to claim 2, in the curved lens according to claim 1, the microlens array surface C is smooth, for example, as shown in FIG.
With this configuration, since both the Flennel lens surface and the microlens array surface are smooth, an image seen through the curved lens is not suddenly distorted, and is smooth and less uncomfortable.

  Further, according to a third aspect of the present invention, in the curved lens according to the first or second aspect, for example, as shown in FIG. 3, the microlens array surface C is the first and second Frennel lens surfaces A. , B, and is a boundary surface between the solid members 20 and 30 having different refractive indexes.

  With this configuration, two Frennel lens surfaces can be formed on the outer surface of the curved lens in contact with the air on the front and back surfaces, so that both Frennel lens surfaces have a large refractive index ratio. On the other hand, the microlens array surface is a boundary surface that contacts a solid member having a small refractive index ratio. On the microlens array surface, each small convex lens and small concave lens have a small area, so the curvature is inevitably large. Therefore, a small lens with a large curvature on the microlens array surface is sandwiched between two Frennel lens surfaces that are in contact with air with a small curvature, so that the focal length of the small lens on the microlens array surface and the Frennel lens surface are the same. can do. As a result, the Frennel lens surface and the microlens array surface can both work effectively, the synergistic effect of the three-dimensional effect, and a stronger three-dimensional effect can be obtained. It is possible to obtain an integrally structured curved lens without using a separate part.

  According to a fourth aspect of the present invention, in the curved lens according to any one of the first to third aspects, the focal length of the microlens array surface C is the first or / and the second Frennel lens. It is almost equal to the focal length of the surfaces A and B.

Here, the focal lengths are almost equal means that the focal length of the Frennel lens surface and the focal length of the small lens on the microlens array surface do not differ until the digits are different, but up to several times the difference. ing. The surface of the Frennel lens has a large area, and the focal length varies depending on the position. That is, there is a local focal length corresponding to the local area, and this value changes for each local area. Such a value including a wide local focal length is collectively referred to as a focal length. Further, the focal distance may be assigned a positive value to the convex lens and a negative value to the concave lens, but all the focal distances are treated as positive values to express the strength of the lens.
If comprised in this way, since both a Frennel lens surface and a micro lens array surface act effectively, both expression power of a three-dimensional effect acts synergistically and a more powerful three-dimensional effect is acquired.

  According to a fifth aspect of the present invention, in the curved lens according to any one of the first to fourth aspects, the first direction in which the change of the generating curved surface is maximum in the first Flennel lens surface A is provided. And the second direction in which the change of the mother curved surface is maximum in the second Frennel lens surface B is substantially parallel.

Here, “substantially parallel” means substantially parallel including manufacturing variations.
If comprised in this way, since the lens characteristic of two Frennel lens surfaces mutually strengthens in one direction, the curvature of each Frennel lens surface can be made small. The effective area of the lens can be enlarged compared to the case of a single Frennel lens surface exhibiting equivalent lens characteristics, and the step side walls can be lowered and the step side wall height can be reduced by equalizing the step distance of the Frennel lens. In the case of equality, the lens can be easily manufactured by increasing the width of the element. In addition, the direction in which the change of the generating surface is the same between the two Frennel lens surfaces is the same, and the direction in which the steps are aligned is also the same, so there is an ineffective zone due to the effective lens surfaces on the front and back sides and the side walls of the steps. The basic period in which the effective lens surface and the invalid zone are repeated together becomes smaller. This irregularity is further promoted when the gap between the steps is irregular. These effects can reduce the moire fringes.

  According to a sixth aspect of the present invention, in the curved lens according to any one of the first to fourth aspects, the first direction in which the change of the generating curved surface is maximum in the first Flennel lens surface A is provided. And the second direction in which the change of the mother curved surface is maximum in the second Frennel lens surface B is substantially orthogonal.

Here, “substantially orthogonal” means substantially orthogonal including manufacturing variations.
With this configuration, the directions in which the two Flennel lens surfaces change greatly are orthogonal to each other, so if the characteristics of both lens surfaces are made comparable, the image viewed through this curved lens will be almost the same in all directions. It appears as an image with little distortion when enlarged or reduced. Since the characteristics of the lenses on both sides can be freely selected, it is possible to obtain a degree of freedom that it is easy to obtain a curved lens suitable for display screens having different aspect ratios. In addition, both Frennel lenses can express a three-dimensional effect, and they act together to produce a stronger three-dimensional effect. In this case, since the curvature of each Frennel lens surface can be reduced, a curved lens having a large effective area can be obtained. Further, the height of the side wall of the step can be reduced, and moire fringes can be reduced. In addition, the width of the element can be increased by making the height of the side wall formed at the boundary of the element equal to or less than a predetermined height, and the manufacture of the Frennel lens surface is facilitated.

Further, the invention according to claim 7 is the curved lens according to any one of claims 1 to 6, wherein, for example, as shown in FIGS. 2 and 3, the first or second Frennel lens surface. The distance between the steps A and B is irregularly arranged and / or the size or position of one or both of the small convex lenses i1 to i5 and the small concave lenses i1 ′ to i5 ′ on the microlens array surface C are irregularly arranged. Yes.
When configured in this manner, the interval between the steps of the Frennel lens surface becomes irregular, and the invalid zones due to the effective lens surface and the side wall are irregularly arranged, so that moire fringes can be reduced. Alternatively, moire fringes can be reduced due to irregularities of small lenses on the microlens array surface.

  In order to solve the above problem, the curved lens according to claim 8 is a Frennel lens surface having a single smooth convex surface or a single smooth concave surface as a mother curved surface as shown in FIG. 10, for example. B ″ ′ and a microlens array surface D ″ ′ formed by alternately arranging small convex lenses t and small concave lenses t ′ having a sufficiently small area with respect to the area of the Frennel lens surface B ″ ′. The lens array surface D ″ ′ is a boundary surface between two solid members 50 and 52 having different refractive indexes, and has a step at a position corresponding to the step of the Fresnel lens surface B ″ ′ along the Fresnel lens surface B ″ ′. Are arranged.

  Here, being arranged along the Fresnel lens surface means that the distance from the Fresnel lens surface is relatively short, and the microlens array surface also has a step at a position corresponding to the step of the Fresnel lens surface. This means that the step of the micro lens array surface is arranged at a position where at least one third of the step of the Frennel lens surface can be secured. The distance from the microlens array surface to the Frennel lens surface may vary to some extent.

  With this configuration, the microlens array surface is a curved surface, and the small lenses arranged on this surface are tilted with the curvature. This inclination changes the characteristics of the small convex lens and the small concave lens with the place. As a result, the curvature itself causes a third strong difference between the retinal images of the right eye and the left eye, which is caused by the first difference due to the Frennel lens surface and the individual small lenses on the microlens array surface (curving. In addition, the second difference (which occurs even when the camera is not tilted) adds a strong three-dimensional effect.

According to the ninth aspect of the present invention, in the curved lens according to the eighth aspect, the small convex lens t and the small concave lens t ′ forming the microlens array surface D ″ ′ form a step on the Frennel lens surface B ″ ′. It is connected smoothly except for the corresponding position.
With this configuration, since the Frennel lens surface and the microlens array surface are both smooth, the image seen through the curved lens is not abruptly distorted, and the image is smooth and easy to see with little discomfort.

According to a tenth aspect of the present invention, in the curved lens according to the eighth or ninth aspect, the focal length of the microlens array surface D ″ ′ is substantially equal to the focal length of the Frennel lens surface B ″ ′.
If comprised in this way, a Frennel lens surface and a micro lens array surface can work together effectively, the expression power of a three-dimensional effect acts synergistically, and a more powerful three-dimensional effect is obtained.

According to an eleventh aspect of the present invention, in the curved lens according to any one of the eighth to tenth aspects, the step interval of the Frennel lens surface is irregularly and / or the microlens array surface C. The size or position of either one or both of the small convex lens and the small concave lens is irregularly arranged.
With this configuration, moire fringes can be reduced because the gap between the steps of the Frennel lens surface is irregular and the effective lens surface and the invalid zone of the side wall are irregularly arranged. Alternatively, moire fringes can be reduced due to irregularities of small lenses on the microlens array surface.

  Further, according to a twelfth aspect of the present invention, in the curved lens according to any one of the first to eleventh aspects, for example, as shown in FIG. 5, the normal line on the Frennel lens surface B ′ is in a specific direction. The angle formed by this straight line is either an acute angle or an obtuse angle at any point on the Frennel lens surface B ′. In FIG. 5, the angle θ between the normal h of an arbitrary point g in the element B9 ′ of the Frennel lens surface B ′ and the straight line q in the specific direction when the specific direction is the vertical direction is any of the Frennel lens surfaces. An acute angle is also obtained at this point.

Here, the angle formed with a straight line in a specific direction refers to an angle measured from a half line representing one predetermined direction in the specific direction to a normal line around the same.
If comprised in this way, the direction of a Frennel lens surface will become the same with respect to a specific direction in any place. That is, the Frennel lens surface is inclined in the same direction with respect to a specific direction. Thereby, the reflected light on the surface of the Frennel lens can be directed in a specific direction. For example, when the Frennel lens surface is directed downward in the vertical direction, the illumination light from above and behind the head can be reflected in the direction below the eye to eliminate the influence of the illumination light. In addition, since the Frennel lens surface is inclined, the characteristics of the lens are enhanced, and the stereoscopic effect can be expressed more strongly.

  In order to solve the above problem, the curved lens according to claim 13 is a Frennel lens having, as shown in FIG. 6, for example, a single smooth convex surface or a single smooth concave surface as a mother curved surface. Surface A ′, small convex lenses j1 to j6, and small concave lenses j1 ′ to j6 ′ are alternately arranged, and a part or all of the junctions between the small convex lenses and the small concave lenses adjacent to each other are curved surfaces of both lenses. In a discontinuous junction state where the tangent lines do not coincide with each other, the short sides of the small convex lenses j1 to j6 and the small concave lenses j1 ′ to j6 ′ are 1/500 or less the length of the short side of the Frennel lens surface A ′. And a lens array surface C ′.

Here, the short side is the length of the object projected on a plane orthogonal to the long side, with a straight line connecting the two most distant points in the object as the long side.
With this configuration, the part where the curved surface of the lens changes suddenly and the image is greatly distorted is limited to a thin area that hits the boundary between the image of the small convex lens and the small concave lens with little distortion. The short side of the image of the concave lens is as small as 1/500 of the short side of the Frennel lens surface, and is small enough to be regarded as one point for a display screen viewed through this curved lens, and the image is greatly distorted. Can be made inconspicuous as distortion because it is smaller than these. Thus, the large distortion due to the discontinuous joining of the small convex lens and the small concave lens can eliminate the influence of the distortion on the entire display image. For this reason, discontinuous joining is allowed, so that it is possible to configure a configuration in which small lens sizes and positions that are relatively small in both length and width are arranged irregularly, or a configuration in which small lenses having the same curvature radius and different sizes are arranged. In addition, it is not necessary to arrange the small convex lens and the small concave lens smoothly and side by side, it becomes easy to manufacture the microlens array surface, and it becomes easy to supply a curved lens capable of reducing moire fringes.

  According to a fourteenth aspect of the present invention, in the curved lens according to any one of the first to thirteenth aspects, the local focal length of the peripheral portion of the Frennel lens surface is larger than the local focal length of the central portion. .

Here, the local focal length refers to a focal length at a local position when the focal length of the Frennel lens surface changes locally depending on the position of the surface.
If comprised in this way, a big difference will arise in the center part of a curved lens in the retina image of right and left eyes, and a big three-dimensional effect will express in a whole image. On the other hand, since the enlargement or reduction ratio of the image is small at the peripheral portion, the degree of appearance of the straight line that is the outermost frame of the display image can be reduced when viewed from an oblique direction, and is unnecessary at the peripheral portion. Since curving can be eliminated, a curved lens having a wide effective area can be obtained.

  In order to solve the above problem, a display device according to a fifteenth aspect includes, for example, as illustrated in FIG. 1, the curved lens 10 according to any one of the first to fifteenth aspects and the curved lens. 10, the two-dimensional display image 11 disposed opposite to the image display 10, and the holding mechanism 12 b that maintains the positional relationship between the two-dimensional display image 11 and the curved lens 10 are provided.

Here, the two-dimensional display image is a two-dimensional display image composed of a continuous pattern viewed from one point such as a photograph that is typically commonly seen, and is not limited to a plane, but is in a curved state. These two-dimensional display images are also included. In addition, a two-dimensional display image that is partly mosaic but continuously viewed from a distance is also included.
When configured in this way, the display device is configured using the curved lens according to the present invention, so that the stereoscopic effect is strong, and by using a curved lens with a wide effective area, the stereoscopic effect is strong, A large area display screen can be realized with a device having a small depth dimension.

  According to one aspect of the present invention, a curved lens that can be applied to a wider and thinner display screen is provided by using two or more Frennel lens surfaces, and the curved lens can be placed close to the display screen. A large-screen stereoscopic display device can be realized with a relatively thin shape.

  In addition, according to the present invention, by using a microlens array surface in which convex lenses and concave lenses are alternately arranged in combination with a Frennel lens surface, it is possible to enhance the expression of stereoscopic effect and to feel uncomfortable due to image distortion that occurs. A curved lens that can be reduced can be provided, and a stereoscopic image display device with good image quality can be realized. Moreover, in the aspect which arrange | positions this micro lens array surface along a Frennel lens surface, a three-dimensional effect can be expressed still more strongly.

  Further, according to another aspect of the present invention, by introducing irregularity into the arrangement of the elements constituting the Flennel lens curved surface, or into the arrangement of the small concave surface and the small convex surface of the constituent elements of the microlens array surface, Moire fringes can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a display device according to the first embodiment of the present invention.
In FIG. 1, the display device includes a curved lens 10, a display image 11 depicting a pattern to be displayed, a back plate 12a holding the display image 11, and arms 12b attached to the four corners of the back plate 12a. The curved lens 10 is attached to the arm 12b. The back plate 12 a and the arm 12 b constitute a holding mechanism 12 that holds the relative positional relationship between the display image 11 and the curved lens 10.

  The embodiment shown in FIG. 1 is such that the distance from the curved lens 10 to the display image 11 is sufficiently smaller than the distance to the observer, and the curved lens 10 and the display image 11 can be regarded as one display device. The display image 11 is a planar two-dimensional display image composed of continuous symbols drawn on normal paper, and the lengths of the arms 12b attached to the four corners of the back plate 12a are the same, and a flat curved surface. The lens 10 is placed in parallel with the display image 11.

  In addition, the arrow shown in the figure indicates a spatial direction, and a direction that faces the front of a planar display image that is set up vertically by an observer is a direction z, and is on a plane orthogonal to the direction z. A direction connecting both eyes of the observer is indicated as a direction x, and a direction orthogonal to the direction z and the direction x is indicated as a direction y. Except for special cases, since a straight observer generally sees a vertically-displayed image directly facing the observer, these directions x, y, and z are referred to as the left and right directions of the eyes and the eyes, respectively. Also referred to as the vertical direction and the depth direction. The left-right direction of the eye is also referred to as the horizontal direction, and the up-down direction of the eye is also referred to as the vertical direction. In addition, the thick arrow shown in the figure shown below has shown the spatial direction demonstrated here.

  Each arm 12b attached to the four corners of the back plate 12a has a mechanism for adjusting the length. By changing the length, the distance between the curved lens 10 and the display image 11 can be made variable. The display image 11 can also be tilted obliquely. Furthermore, using a flexible curved lens that is longer in length and breadth than the back plate 12a, the curved lens 10 faces the display image 11 in a curved state by setting the mounting positions of the curved lens 10 to the arm 12b as four corners. You can also put it.

  In the first embodiment shown in FIG. 1, the display image has been described as a display device that uses a planar two-dimensional display image drawn on paper. However, a TV receiver, a personal computer monitor, a mobile phone, etc. The display device according to the present invention can be provided, and these are also provided with means for receiving a communication image or a broadcast image. The display image 11 is a two-dimensional display image composed of continuous symbols viewed from one point. In these display devices, a display screen such as a cathode ray tube or liquid crystal that is electronically controlled to display an image corresponds to the display image 11, and a curved lens 10 is placed facing the display screen 11, and the display screen 11 and the curved lens are arranged. The holding mechanism 12 that holds the 10 relative positional relationships corresponds to a mechanism portion called a casing or a frame that fixes both. In these electronic display devices, the display image 11 is strictly a discontinuous pattern in which small image areas called pixels are arranged, but the observer cannot distinguish individual pixels as one continuous pattern. Looking. In the present invention, such a display image is also included in a continuous two-dimensional display image.

  Further, a display device such as a projector projected on the screen is also included in the display device according to the present invention because a mechanism for maintaining the positional relationship between the screen and the curved lens is necessarily provided if a curved lens is placed in front of the screen. . Also, the two-dimensional display image is an image drawn on a two-dimensional surface, and an image obtained by curving an image drawn on a plane is also included in the two-dimensional display image.

  2 is a perspective view conceptually showing the configuration of the curved lens 10 used in the first embodiment shown in FIG. 1, and FIG. 3 is a straight line α-α shown at the center of the curved lens in FIGS. FIG. 3A is a cross-sectional view in which a plane parallel to the x-axis and the z-axis including 'and a plane perpendicular to the y-axis is taken as a cut surface and a shape of a small lens surface. FIG. Yes.

  Various embodiments will be described below, all of which have the same device configuration as the display device of the first embodiment shown in FIG. Therefore, when “the device configuration is the same as that of the display device of the first embodiment” in the following description, except for the curved lens, the other display image 11 and the holding mechanism 12 including the back plate 12a and the arm 12b, etc. Are assumed to perform the same function with the same configuration as the display device of the first embodiment. Further, the positional relationship between the curved lens and the display screen is the same, and the mounting of the curved lens to the holding mechanism 12 is the same. The difference is in the curved lens itself.

  Further, in the explanation of the cross-sectional view of the curved lens in the embodiment concerned, when the “horizontal cut plane explained in the first embodiment” is used, the straight line α-α ′ shown in the central portion of the curved lens in FIG. A plane parallel to the x-axis and z-axis and including the vertical axis is perpendicular to the y-axis. Further, in the explanation of the cross-sectional view of the curved lens in the embodiment concerned, when the “vertical cut surface explained in the first embodiment” is used, the straight line β-β ′ shown in the central portion of the curved lens in FIG. A plane that is parallel to the y-axis and the z-axis and that is perpendicular to the x-axis is taken as the cut surface.

The curved lens according to the first embodiment will be described in detail with reference to FIGS.
FIG. 2 conceptually shows the configuration of the curved lens 10. The outer surface A facing the display image 11 of the curved lens 10 and the outer surface B facing the opposite observer are Frennel lens surfaces. Hereinafter, the outer surface of the curved lens facing the display image 11 is also referred to as a back surface or a back outer surface. The outer surface on the opposite side of the viewer is also referred to as the front side or the outer surface. These Frennel lens surfaces A and B are expressed by arranging the elements A1 to A4 and B1 to B4 (see FIG. 3) with steps. Here, it is a conceptual diagram that expresses that the number of elements is limited and the elements having different widths are irregularly arranged, but in actuality, a large number of elements having a finer width are arranged. A step is generated at the boundary of each element, and the side wall is visible. This visible side wall is shown in gray (see FIG. 2). The width of the element is also the step interval.

  The Frennel lens surface of the outer surface A is a boundary surface between the member 20 and air, and the Frennel lens surface of the outer surface B is a boundary surface between the member 21 and air. A lens surface also exists in a portion 22 (schematically shown by a bold line in FIG. 2) sandwiched between the member 20 and the member 21. This portion 22 is an adhesive 30, and a lens surface exists at the boundary surface between the adhesive 30 and the member 20, and this lens surface is a microlens array surface C in which a large number of small lens surfaces are alternately arranged. . Although not shown in detail in FIG. 2, details will be described in FIG.

FIG. 3 shows an enlarged part of the cross section of the curved lens 10. The Frennel lens surface and the microlens array surface will be described in more detail with reference to FIG.
The member 20 on which the Fresnel lens surface A is formed has a curved surface in which small small concave surfaces i1 ′ to i4 ′ and small convex surfaces i1 to i4 are alternately arranged on a surface C opposite to the Fresnel lens surface A. Yes. On the other hand, the surface opposite to the Fresnel lens surface B of the member 21 on which the Fresnel lens surface B is formed is a flat surface. The flat surface of the member 21 and the surface C in which the small concave surfaces and the small convex surfaces of the member 20 are alternately arranged are bonded to each other by the adhesive 30. A boundary surface between the adhesive 30 and a surface in which small concave surfaces and small convex surfaces of the member 20 are alternately arranged becomes a microlens array surface C, and the small concave surfaces i1 ′ to i4 ′ and the small convex surfaces i1 to i4 are small lenses. It is.

  A structural concave surface or convex surface can be a concave surface or a convex surface depending on the viewpoint. Here, the part traveling toward the outside of the member 20 is described as a convex surface, and the part retracted toward the inside is regarded as a concave surface. However, in the following description, if there is no particular need to refuse, the member is appropriately selected to be outside. In the following description, it is assumed that the portion that is traveling toward the convex side is a convex surface, and the portion that is drawn inward is a concave surface. If the refractive index of the member 20 is n1 and the refractive index of the adhesive 30 is n2, the structural convex surface or concave surface becomes a convex lens or a concave lens depending on the magnitude relationship between n1 and n2. In the following description, the description will be made on the assumption that the structural convex surface is an optically convex lens and the structural concave surface is an optically concave lens. Note that the refractive index of the adhesive 30 and the member 20 is appropriately selected so that the focal length of the small lens on the microlens array surface is substantially equal to the focal length of the Frennel lens surface.

The generative surfaces of the Frennel lens surfaces A and B are indicated by dotted thick lines as a and b, respectively. The lens surfaces A1 to A5 of the elements constituting the Frennel lens surface A correspond to the elements a1 to a5 of the mother curved surface, respectively. The lens surfaces B1 to B5 of the elements constituting the Frennel lens surface B correspond to the elements b1 to b5 of the mother curved surface, respectively. The Frennel lens surface is a surface in which each element of the generating surface is translated along a cut surface (indicated by a thin dotted line).
The mother curved surface does not change in the y direction perpendicular to the paper surface, and the thickness of the lens corresponding to the z direction changes only in the x direction. A typical example of such a generating surface is a cylindrical surface, which is also a cylindrical surface. The lens surfaces of the elements A1 to A5 and B1 to B5 constituting the Frennel lens surfaces A and B naturally do not change in the y direction, and the thickness of the lens corresponding to the z direction changes only in the x direction. .

  The Fresnel lens surfaces A and B become discontinuous at the boundary surface between adjacent elements, resulting in a step. When this lens is viewed from an oblique direction, the side wall portion of the step becomes an invalid zone. As the degree of viewing from an oblique direction increases, the ratio of the invalid zone to the lens surface increases. This is clearly shown in FIG. Further, the widths of the elements of the Fresnel lens surface A and the Fresnel lens surface B, that is, the gaps between the steps are irregular. For example, several types of element widths are determined, and the widths of the elements are changed irregularly while randomly selecting from these.

Next, the microlens array surface will be described.
In the microlens array surface C31, small convex surfaces i1 to i4 and small concave surfaces i1 ′ to i4 ′ indicated by bold lines are alternately arranged. These small curved surfaces are also small lenses i1 to i4 and i1 ′ to i4 ′. These lenses are cylindrical lenses, and a diagram in which the lenses are arranged with the central axis O aligned is shown in FIG. Yes. As is clear from this figure, they all have the same central angle and the same gradient at the end of the lens surface. Therefore, the microlens array surface C in which these small lenses i1 to i4 and i1 ′ to i4 ′ are connected is a smooth curved surface. In addition, these small lenses have different radii of curvature and different focal lengths. Here, the smooth curved surface is a surface having no discontinuous joint where the tangents of the curved surface of the lens do not coincide. Also, there is a case where a sufficiently small plane is interposed between the small convex lens and the small concave lens, and these are smoothly connected. This is included in a state where small convex lenses and small concave lenses are alternately arranged.

  On the microlens array surface C, cylindrical surfaces having the same central angle but different radii are arranged, so that small lenses having different widths are irregularly arranged. Specifically, several types of cylindrical surfaces having different widths, that is, different central angles, are prepared, and the convex surface and the concave surface are selected so that the convex surface is a concave surface and the concave surface is a convex surface while being irregularly selected. They are arranged alternately.

In the first embodiment described above, a smooth microlens array surface C is sandwiched between two Frennel lens surfaces A and B. Both of the mother curved surfaces of the two Frennel lens surfaces A and B form a single convex surface that fills the entire area of the curved lens 10, and both Frennel lens surfaces A and B function as a single convex lens. On the other hand, the microlens array surface C is a smooth surface in which small convex lenses i1 to i4 and small concave lenses i1 ′ to i4 ′ having an area sufficiently smaller than the areas of the Frennel lens surfaces A and B are alternately arranged.
Here, a single convex surface is a surface composed only of a convex surface, and a surface whose curvature changes depending on the place is also included in the single convex surface. A single concave surface is a surface consisting of only a concave surface, and a surface whose curvature changes depending on the location is also included in the single concave surface.

The configuration of the first embodiment has been described above. The operation will be described below.
In the present invention, a difference occurs in the retinal images formed on the left and right eyes of a two-dimensional display image viewed through a curved lens, and in response to this, the brain understands it as a three-dimensional image in light of past experience. This is also based on binocular parallax because the stereoscopic effect is strongly felt when viewed with both eyes. In order to feel the three-dimensional effect strongly, it is necessary to make a large difference in the retinal images formed on the left and right eyes, and the distortion of the visible image is increased accordingly. One of the challenges is how to make this distortion feel small.

  In the first embodiment, the Frennel lens surfaces A and B equivalent to a lens curved surface having a large spread so that the distortion extends over the entire screen, and a small lens sufficiently smaller than the Frennel lens surfaces A and B. By superimposing the microlens array surface C on which a large number of surfaces are arranged in multiple layers, the function of expressing both stereoscopic effects is synergistically enhanced. As for the distortion, one is a distortion that extends over a large range over the entire screen, and the other is a distortion that is limited to a small area. The difference between the two areas prevents the distortions from emphasizing each other.

  In particular, distortion due to a large curved lens surface is related to the overall distortion of the display image, and it is important to reduce this distortion. One means for this is to enlarge or reduce the entire screen almost uniformly. Even if it does not enlarge or reduce uniformly, it does not enlarge or reduce depending on the location. If the enlarged portion and the reduced portion coexist, the image distortion will be felt strongly, so this should be avoided. It is effective that the entire screen area is limited to only one of enlargement and reduction, and even if the enlargement ratio or reduction ratio changes with location, the change is gradual.

In the first embodiment, the Frennel lens surfaces A and B are equivalent to a single convex lens surface, so that only one of the enlargement with respect to the entire screen area is reduced, thereby reducing distortion. .
Furthermore, when the enlargement or reduction is limited to the horizontal direction or the vertical direction, there is less discomfort due to the distortion than when the distortion in the oblique direction is involved. In recent TV receivers, a wide screen having a wide horizontal direction is increasing. In such a screen, if it is distorted only in the horizontal direction, it is less uncomfortable to reduce it than it is enlarged, and if it is distorted only in the vertical direction, it is less strange to enlarge it than it is reduced.

  In the first embodiment, the two Flennel lens surfaces change in the left-right direction of the eye, that is, in the horizontal direction and do not change in the vertical direction. For this reason, the degree of feeling the distortion of the display image without the distortion in the oblique direction is reduced. In addition, since the lens surface changes in the left-right direction of the eye, a large difference appears in the retinal images of the left and right eyes, and a three-dimensional effect appears strongly.

  On the other hand, the microlens array surface C is a smooth curved surface, and these small curved surfaces i1 to i4 and i1 'to i4' have the same central angle but different radii of curvature, that is, widths. The tangents at the ends of these small curved surfaces are all equal because they have different widths but the same central angle. That is, the curved surfaces are smoothly connected even at the boundaries between the small small concave surfaces i1 'to i4' and the small convex surfaces i1 to i4. Since the microlens array surface C is smooth and the gradient of the curved surface does not change abruptly, large distortion can be removed and image quality can be improved. Further, since the small concave lenses i1 'to i4 and the small convex lenses i1 to i4 are alternately arranged, a strong stereoscopic effect appears. Furthermore, the direction of the lens change is the left-right direction of the eye, and a large difference occurs between the left and right retinal images, which also enhances the three-dimensional effect.

  In the first embodiment, as a means for preventing the feeling of distortion, the microlens array surface C is used as a means for constraining the distortion by limiting each distortion to a narrow region, and the entire image is substantially uniform. Frennel lens surfaces A and B are used as means for making the distortion inconspicuous so that the distortion becomes inconspicuous, and these two lens surfaces act synergistically to make the three-dimensional effect appear stronger.

Next, a problem with respect to the size of the screen as a display device will be described.
The length L of one side of the display image 11 cannot be increased beyond the diameter (2r) of the lens curved surface.
Actually, the cylindrical surface cannot be used up to the full diameter, and the central angle is large, such as 90 ° in the central angle (45 ° each on the left and right), more preferably 60 ° in the central angle (30 ° each on the left and right). In terms of position, it is necessary to use the lens with restrictions because the lens curved surface changes too much.

  Under these restrictions, L ≦ 1.414 × r when the central angle is up to 90 °, and the allowable length of one side of the display image is limited to 1.414 times the radius. Further, when the central angle is 60 °, the radius is limited to L ≦ r and the length of the radius. Furthermore, considering the case of viewing from an oblique direction, it is necessary to provide a margin on both sides, and the width of an image that can be displayed is further limited.

  This restriction on the size of the display screen is also related to the required image magnification, that is, the distance between the curved lens and the display screen. Here, an overview of the extent of the effective area of the Frennel lens surface by a plano-convex lens composed of a Frennel lens surface and a flat surface will be described. The generative surface of the Frennel lens surface, which is a lens surface, is a cylindrical surface with a radius r, and the description will proceed by approximating an area where all lens surfaces can be regarded as paraxial rays near the apex.

The magnification m of the image is obtained by the following equations (Equation 1) and (Equation 2), where n is the refractive index of the lens.
m = f / (d + f) (Equation 1)
1 / f = (n−1) / r (Expression 2)

  Here, f is the focal length, the convex lens surface is positive, and the concave lens surface is negative. m is the magnification of the image, and is an erect image when positive and an inverted image when negative. d is a distance from the lens curved surface of the display image and is always a negative value. R is the radius of curvature of the lens surface, which is positive for convex lens surfaces and negative for concave lens surfaces. When the image magnification m and the distance d between the lens and the display image are determined, the focal length f is determined. As a result, the curvature radius r is determined.

Here, an example is given by applying specific numerical values.
The refractive index n of the member forming the lens surface, the magnification m directly related to the degree of stereoscopic effect, and the distance d between the display image and the lens curved surface are n = 1.5, m = 1.1, d = −, respectively. Assuming 3 cm, the focal length is 33 cm and the radius r is 16.5 cm. Therefore, when the central angle is 90 °, the size of the display image is limited to 33 cm, and when the central angle is 60 °, the size of the display image is limited to 16.5 cm, which is a surprisingly small value.

Further, when the thickness of the lens is estimated as a bulk lens instead of a Fresnel lens type, it is very thick at 4.83 cm when the central angle is 90 ° and 2.21 cm when the central angle is 60 °. From this thickness, it can be well understood that the type of lens in the display device according to the present invention must be a Frennel lens. For example, FIG. 5 shows that if the width of the element is reduced, the thickness of the lens can be sufficiently reduced by using a Frennel lens.
The above d = −3 cm is a value assuming a TV receiver that is generally widespread about 14 inches to 25 inches diagonal, and m = 1.1 is close to the limit of the value necessary to express stereoscopic effect. A small value is assumed. By increasing the value of m, the stereoscopic effect may be strengthened, and in that case, the width of one side of the display image is further restricted.

From the above, it can be seen that the effective area of the Frennel lens surface becomes a very important problem when the area of the display screen is increased.
As described above, the size of one side of the display image 11 is limited to a relatively small value. To avoid this, if the curved lens 10 is separated from the display image 11, the required focal length can be increased and a curved lens having a larger area can be used. However, problems such as an increase in the depth of the apparatus have become apparent. come.

  As a measure for enlarging the effective range without changing the distance from the display image 11 to the curved lens 10, a Frennel lens surface having a double radius of curvature of the mother curved surface is overlapped in two layers. For larger screens, it is necessary to stack more Frennel lens surfaces. What is important here is that they should be stacked in multiple layers and that they must be on the Frennel lens surface. The lens cannot be thin unless it is a Frennel lens surface, and the entire surface of the lens cannot be brought close to the display image.

By superposing two Flennel lens surfaces with a radius of curvature of two layers, the effective area can be enlarged almost twice as long as the focal length is kept at the same level as the original one Flennel lens surface. This is extremely effective in realizing a display device for a display screen.
It is common practice to use a contact surface with air having a small refractive index for the Frennel lens surface. This is because it is a means for reducing the lens thickness, and in order to obtain a predetermined characteristic, a lens interface cannot be used as a boundary surface made of a material having a relatively similar refractive index.
It is relatively easy to make the front and back, which are the outer surfaces of the curved lens, into a Frennel lens, and it can be easily applied to a display device as a single lens, and the thickness of the curved lens can be reduced.

  In the first embodiment, two Frennel lens surfaces A and B whose curved surfaces change in the horizontal direction are used, and the characteristics of both lenses are superimposed to increase the overall lens characteristics. . Further, since the outer surface having a large refractive index ratio between the front and back surfaces of the curved lens in contact with air is used as the Frennel lens surface, the lens characteristics of each Flennel lens surface can be enhanced. Compared to the case where the same lens characteristics are obtained with a single Frennel lens surface, the curvature of each Flennel lens surface can be greatly reduced, the effective area of the curved lens can be widened, and a thin lens with a Frennel lens can be used. Can be configured. Accordingly, a thin and large display device can be realized.

  In the Frennel lens surfaces A and B, there are steps at the boundaries between the elements A1 to A5 and B1 to B5, and the side walls of these steps become invalid zones when viewed from an oblique direction. The invalid zone is arranged alternately with the valid lens surface. If the range of the invalid zone becomes wide, the display image 11 cannot be recognized and the effective viewing angle is restricted. Further, moire fringes are generated by repeating this invalid zone regularly. This moire fringe affects display quality.

Moire fringes are shading stripes that occur when a display image with regularly arranged display pixels is viewed through regularly arranged array elements, and greatly affects display image quality.
Although moiré fringes are well known, detailed description thereof will be omitted. However, the moiré fringes are generated due to the mutual relationship between the array elements on the display image 11 side and the array elements constituting the curved lens 10 as a target here. The array element on the display image side is a pixel such as a liquid crystal display element, and in the case of a curved lens, it is an element on a Frennel lens surface or a small lens on a microlens array surface.

Moire fringes appear strongly when the arrangement pitch of the array elements of the display elements and the arrangement pitch of the array elements of the curved lens 10 are approximately the same. Further, the larger the invalid zone of the array element of the display element and the invalid zone of the array element of the curved lens, the more moire fringes appear. When there is no invalid zone, moire fringes do not occur.
When the arrangement pitch is greatly different, moire fringes can be almost ignored.

  One means for reducing moire fringes is to eliminate regularity by irregularly arranging either or both of the array elements of the display elements and the array elements of the curved lens. The other is to greatly separate the arrangement pitch from each other.

  When two Flennel lens surfaces having a radius of curvature of the mother curved surface increased to about twice are overlapped, the invalid zone per layer can be reduced to about 1/2, and the ratio to the lens surface is also reduced to about 1/2. However, if the directions of the curved surface changes of both Frennel lens surfaces A and B coincide, the arrangement directions of the elements A1 to A5 and B1 to B5 also coincide, so that one invalid zone is a part of the other effective lens surface. Disable it. Therefore, when viewed comprehensively, the ratio of the invalid zone to the effective lens surface is not much different.

  However, by using two layers, the frequency of repeating the effective lens surface and the ineffective zone is doubled, and the same effect as when the elements are arranged at a narrower pitch can be obtained, and moire fringes can be reduced. .

In the first embodiment, the elements A1 to A5 and B1 to B5 that constitute the Frennel lens surfaces A and B are arranged so that the arrangement of the invalid zone by the side wall of the Frennel lens and the effective lens curved surface becomes irregular. They are arranged with irregular widths. Moreover, the irregular arrangement of the two Flennel lens surfaces A and B is not the same but different. Since the elements A1 to A5 and B1 to B5 of the two Frennel lens surfaces A and B are aligned in the same direction, the invalid zone and the effective zone on these two surfaces are united and the irregularity is further strengthened. In addition, the basic period to be repeated is also halved, and the period can be greatly different from the period of the pixels of the display image, and the generation of moire fringes can be greatly reduced.
Further, small lenses with different widths are irregularly arranged on the microlens array surface, and this also reduces moire fringes.

  In the first embodiment, a configuration is adopted in which the microlens array surface C in which the lenses having a small spread are arranged on the Fresnel lens surfaces A and B functioning as a wide spread lens is sandwiched.

Since a lens with a large spread and a lens with a small spread make a difference in the image formed on the retina of both eyes, the characteristics of both lenses, that is, the focal length is the same, and both lenses work together. Need to function.
If a lens with a small spread becomes as small as the pixels of the display image 11, it becomes difficult to perceive the distortion caused by the lens with a small spread as a distortion. Therefore, in order to strengthen the characteristics as a lens and increase the expression of stereoscopic effect, Although the focal length of both lenses may be changed, for example, by reducing the focal length in comparison with a large lens, it does not make a large difference to the extent that the digits are different. At most several times, each of the two lenses functions and works with each other. Therefore, it can be said that the focal length is almost the same up to the difference of several times. In addition, the focal length has a polarity and the convex lens may have a positive value and the concave lens may have a negative value.However, these are applied to the lens formula, etc. Positive values are also used for concave lenses. Unless otherwise noted, all focal lengths are treated as positive values. That is, the focal length refers to the absolute value of the focal length.

  A large lens has a full display screen, for example, several tens of centimeters in length, and a small lens may be almost the same as a display pixel, for example, several hundreds of micrometers in length, which is about 1000 times different. This is an example, and when the distortion of a lens with a small spread is made inconspicuous, the difference between a lens with a large spread and a lens with a small spread is 100 to 1000 times long. is there. It is difficult to form curved surfaces having different spread areas with curved surfaces having the same degree of curvature radius, and the ratio of the curvature radii must be the same as the ratio of the spread areas. Under these structural conditions, in order to realize a lens surface with the same focal length, a large lens uses a boundary surface that contacts air as a lens surface, and a small lens surface has a relatively similar refractive index between members. This is to make the joint surface of the lens a lens surface.

  In order to satisfy the above conditions, as shown in the first embodiment, the structure in which the microlens array surface C is sandwiched between the two Flennel lens surfaces A and B is the most suitable structure for the curved lens 10 used in the display device. is there. In other words, the Frennel lens surfaces A and B that need to be in contact with air use the outer surface, and the microlens array surface C that should have the lens surface as the boundary surface of the relatively similar refractive index material can be configured inside. This is because the curved lens 10 in which these lens surfaces are integrated can be configured.

Next, a second embodiment will be described in detail with reference to the drawings.
The device configuration of the display device of the second embodiment is the same as that of the display device of the first embodiment. The difference is in the curved lens.

In the second embodiment, the outer front surface and the rear outer surface of the curved lens are both Frennel lens surfaces, as in the first embodiment. However, the curved surfaces of the front and back Frennel lenses in the first embodiment both change with respect to the left-right direction of the eye, whereas they do not change with respect to the vertical direction of the eye perpendicular to this. In the second embodiment, the front and back Frennel lens curved surfaces both change with respect to the vertical direction of the eye, and do not change with respect to the horizontal direction of the eye perpendicular thereto.
The microlens array surface is also sandwiched between both Frennel lens curved surfaces as in the first embodiment. However, the arrangement of elements constituting the Frennel lens curved surface and the microlens array surface are configured. There are differences such as the curvature radius of the small lens being different.

The curved lens according to the second embodiment will be described in detail with reference to FIGS. 4, 5, and 6.
FIG. 4 is a perspective view conceptually showing the configuration of the curved lens 10.
FIGS. 5 and 6 are a vertical sectional view and a horizontal cut surface, respectively, showing the curved lens 10 according to the display device of the second embodiment. The positions and directions of the cutting planes in the vertical sectional view and the horizontal sectional view are the same as the vertical cutting plane and the horizontal cutting plane described in the first embodiment.

First, the outline of the configuration of the curved lens 10 will be described with reference to FIG.
Each of the elements A1 ′ to A14 ′ and B1 ′ to B14 ′ (see FIG. 5) indicates that the back outer surface A ′ facing the display image 11 and the front outer surface B ′ facing the opposite observer are Frennel lens surfaces. 5) is expressed by being arranged with steps. Here, the number of elements is limited, and it is a conceptual diagram showing that the elements are arranged in the y direction. However, in fact, many narrower elements are arranged and the width of the elements is small.

The Frennel lens surface of the outer surface A is a boundary surface between the member 40 and air, and the Frennel lens surface of the outer surface B is a boundary surface between the member 41 and air. A lens surface also exists in a portion 42 (schematically shown by a bold line in FIG. 4) sandwiched between the member 40 and the member 41. This portion 42 is an adhesive 43, and a lens surface exists at the boundary surface between the adhesive 43 and the member 40. This lens surface is a microlens array surface C ′ in which a large number of small lens surfaces are alternately arranged. is there. Although details are not shown in FIG. 4, details are described in FIG.
Further, in FIG. 4, the side wall at the boundary between the elements B1 ′ to B14 ′ of the Fresnel lens surface B ′ can be seen. This visible side wall is shown in gray.

The curved lens 10 will be described in more detail with reference to FIGS.
In FIG. 5, the mother curved surfaces of the Fresnel lens surface A ′ and the Fresnel lens surface B ′ are indicated by a thick dotted line as a ′ and b ′, respectively. The lens surfaces A1 ′ to A14 ′ of the elements constituting the Frennel lens surface A correspond to the elements a1 ′ to a14 ′ of the mother curved surface, respectively. Further, the lens surfaces B1 ′ to B14 ′ of the elements constituting the Frennel lens surface B ′ correspond to the elements b1 ′ to b14 ′ of the mother curved surface, respectively. The Frennel lens surface is a surface in which each element of the generating surface is translated along a cut surface (indicated by a thin dotted line).

  The portion 42 sandwiched between the Fresnel lens surface A ′, which is the outer surface of the member 40, and the Fresnel lens surface B ′, which is the outer surface of the member 41, is an adhesive 43, and the boundary surface between the adhesive 43 and the member 40 There is a microlens array surface C ′. Note that the refractive index of the adhesive 43 and the member 40 is appropriately selected so that the focal length of the small lens on the microlens array surface is substantially equal to the focal length of the Frennel lens surface.

  The mother curved surfaces a 'and b' do not change in the x direction perpendicular to the paper surface, and the thickness of the lens corresponding to the z direction changes only in the y direction. A typical example of such a generating surface is a cylindrical surface. Here, both the Fresnel lens surface A ′ and the Fresnel lens surface B ′ are cylindrical surfaces whose central axes are perpendicular to the paper surface and are convex lenses.

The Frennel lens surfaces A ′ and B ′ become discontinuous at the boundary surface between adjacent elements, resulting in a step. When the lens is viewed from an oblique direction, the side wall portion of the step portion is an ineffective zone (shown in gray in FIG. 4). It becomes. As the degree of viewing from an oblique direction increases, the ratio of the invalid zone to the lens surface increases. This is clearly shown in FIG.
The widths of the elements A1 ′ to A14 ′ and B1 ′ to B14 ′ constituting the Fresnel lens surface A ′ and the Fresnel lens surface B ′, that is, the arrangement pitch of the elements are uniform. The gap between the steps is also uniform.

The orientation of the lens surfaces of the elements B1 ′ to B14 ′ constituting the Fresnel lens surface B ′ satisfies special conditions. That is, the lens surface of each element is inclined downward with respect to the vertical direction.
A straight line q indicating a normal direction h at an arbitrary point g on the Frennel lens surface B ′ (an arbitrary point is set on the element B9 ′ in FIG. 5) (the specific direction is the vertical direction in FIG. 5). The angle θ formed by the downward half line is an acute angle at any location on the surface of the Frennel lens, and is inclined downward in the vertical direction. Here, the angle formed with the straight line in the specific direction is a method in the same direction (clockwise in FIG. 5) from the half line representing the predetermined direction (downward in FIG. 5) of the specific direction (vertical direction in FIG. 5). Says the angle measured up to the line.

  To express the above in general, if the angle between the normal on the Frennel lens surface and the straight line in a specific direction is either an acute angle or an obtuse angle at any point on the Frennel lens surface, Even in the place of, it tilts in a specific direction in a specific direction.

  If comprised in this way, the direction of a Frennel lens surface will become the same with respect to a specific direction in any place. That is, the Frennel lens surface is inclined in the same direction with respect to a specific direction. Thereby, the reflected light on the surface of the Frennel lens can be directed in a specific direction. For example, when the Frennel lens surface is tilted downward in the vertical direction, the illumination light from above and behind the head can be reflected in the direction below the eye to eliminate the influence of the illumination light. In addition, since the Frennel lens surface is inclined, the characteristics of the lens are enhanced, and the stereoscopic effect can be expressed more strongly.

  The above indicates that the generating surface b 'corresponding to the Frennel lens surface B' does not include a vertex. On the other hand, the Frennel lens surface A 'is a very general Frennel lens surface with the corresponding generating curved surface including the apex e. This vertex e is shown in element a7 'of the generating surface a'.

Next, the configuration of the microlens array surface will be described in detail with reference to FIG.
In FIG. 6, small small concave surfaces j1 ′ to j6 ′ and small convex surfaces j1 to j6 are alternately arranged on a surface C ′ of the member 40 on which the Fresnel lens surface A ′ is formed, on the side opposite to the Fresnel lens surface A ′. It is arranged. The small concave surfaces j1 ′ to j6 ′ and the small convex surfaces j1 to j6 constituting the surface C ′ do not change in the y direction perpendicular to the paper surface, and the curved surface changes in the x direction. That is, in the vertical cross-sectional view in which the plane parallel to the y direction is a cut surface, the surface C ′ appears to be a straight line, and the unevenness of the microlens array surface C ′ is not clearly shown.

On the other hand, the surface of the member 41 on which the Fresnel lens surface B ′ is formed is the plane D ′ opposite to the Fresnel lens surface B ′. The plane of the member 41 and the surface of the member 40 in which the small concave surfaces and the small convex surfaces are alternately arranged are bonded to each other by the adhesive 43.
A boundary surface C ′ between the adhesive 43 and the surface where the small concave surfaces j1 ′ to j6 ′ and the small convex surfaces j1 to j6 of the member 40 are alternately arranged becomes a microlens array surface.
Both the Fresnel lens surface A ′ and the Fresnel lens surface B ′ change with respect to the y direction perpendicular to the paper surface and do not change with respect to the x direction.

Next, the microlens array surface will be described.
On the micro lens array surface C, small convex lenses j1 to j6 and small concave lenses j1 'to j6' indicated by thick lines are alternately arranged. The lens surfaces of these small lenses j1 to j6 and j1 ′ to j6 ′ are cylindrical surfaces having a central axis parallel to the y direction perpendicular to the paper surface, and their curvature radii are all equal. A small concave lens and a small convex lens having the same central angle form a pair (j1 and j1 ′, j2 and j2 ′, etc.). There are a plurality of types of pairs with different central angles, and these are randomly selected and arranged in contact with the boundary. The tangent line of the lens curved surface changes discontinuously at the junction between the pair (indicated by black dots in the figure). Since the small lenses j1 to j6 and j1 ′ to j6 ′ constituting the lens curved surface have the same curvature radius, the focal lengths are all equal.

  In the second embodiment described above, the microlens array surface C ′ is sandwiched between the two Frennel lens surfaces A ′ and B ′. The two curved surfaces a ′ and b ′ of the two Flennel lens surfaces A ′ and B ′ each form a single convex surface that fills the area of the curved lens 10 and changes in the y direction, that is, in the vertical direction of the eye. , A single convex lens having a convex surface having the same characteristics as the main curved surfaces a ′ and b ′ on the surface that does not change in the x direction, that is, the left-right direction of the eye. Function as.

  On the other hand, the microlens array surface C ′ is a surface in which small convex lenses j1 to j6 and small concave lenses j1 ′ to j6 ′ having an area sufficiently smaller than the area of the Frennel lens surfaces A ′ and B ′ are alternately arranged. The focal lengths of the small convex lenses j1 to j6 and the small concave lenses j1 ′ to j6 ′ are equal.

The configuration of the second embodiment has been described above. The operation will be described below.
In the second embodiment, as in the first embodiment, the microlens array surface C ′ is sandwiched between two Frennel lens surfaces A ′ and B ′. In addition, the two Frennel lens surfaces A ′ and B ′ are lens surfaces having a large expanse equivalent to a single convex or concave lens surface and using an outer surface in contact with air, and the microlens array surface C ′ is a curved lens 10. Is a lens surface in which small concave surfaces j1 'to j6' and small convex surfaces j1 to j6 having a sufficiently small area as compared with the surface area of the above are used, and the boundary surfaces of members having relatively similar refractive indexes are used. . For this reason, as in the first embodiment, the functions of expressing both three-dimensional effects are synergistically enhanced by stacking the Fresnel lens surfaces A ′ and B ′ and the microlens array surface C ′ in multiple layers. On the other hand, as for the distortion, a large distortion that covers the entire screen by the Frennel lens surfaces A ′ and B ′ and a small distortion that is limited to a small range by the small lens on the microlens array surface C ′ are regionally different. , Avoiding emphasizing each other's distortion.

  In the second embodiment, a part of the junction between the small convex lens and the small concave lens on the microlens array surface is in a discontinuous joint state where the tangents of the curved surfaces of both lenses do not coincide with each other, and the tangent of the lens curved surface is discontinuous. Changes. For this reason, the image of this part is distorted. In order to reduce the effect on image quality due to this distortion, the image of each small convex lens and each small concave lens is regarded as one point or a thin line (when the long side is long) for the display screen viewed through this curved lens. If it is made as small as possible, for example, if one side is compared to be reduced to about 1/500 or less, the greatly distorted portion of this image becomes smaller compared to the image of these small lenses, so that it can be made inconspicuous as distortion. .

In the second embodiment, the direction in which the lens curved surface changes in the two Frennel lens surfaces A ′ and B ′ is the vertical direction, which is different from the case of the first embodiment, which is the horizontal direction. Even if the lens curved surface changes in the vertical direction, the display image 11 and the curved lens 10 are widened, so that a difference in the horizontal direction occurs between the lines of sight of the left and right eyes. Appears and gives a three-dimensional effect.
The advantage of changing the lens curved surface in the vertical direction is that the feeling of discomfort with respect to distortion caused by the lens is reduced by enlarging in the vertical direction with respect to a horizontally long image such as a wide TV, which is often seen recently. In addition, since such an image has a short vertical direction, use of a curved lens whose lens curved surface changes in the vertical direction can relieve the restriction on the effective area of the lens and can greatly increase the size of the apparatus.

In the second embodiment, two Frennel lens surfaces A ′ and B ′ are used, and compared with the case where the same lens characteristics are obtained with a single Flennel lens surface, individual Frennel lens surfaces are used. The curvature of the lens can be greatly reduced, the effective area of the curved lens 10 can be widened, and a thin curved lens can be formed by forming a Frennel lens. Further, the lens characteristics of the curved lens 10 are enhanced by the two Frennel lens surfaces A ′ and B ′, and the curved lens 10 can be placed near the display screen 11.
Accordingly, a thin and large display device can be realized.

  Since the direction in which the elements A1 ′ to A14 ′ and B1 ′ to B14 ′ of the two Frennel lens surfaces A ′ and B ′ are aligned is the same, the invalid zone and the effective zone on these two surfaces are united and repetitive. The period is also halved, and the period can be greatly different from the period of the pixels of the display image 11, and the generation of moire fringes can be reduced.

  The microlens array surface C ′ is a smooth curved surface in which small curvatures with the same radius of curvature and the same central angle are arranged in the first embodiment, but the central angle is different in the second embodiment. Small curved surfaces j1 to j6 and j1 ′ to j6 ′ having the same locality radius are arranged, and the widths of the individual small curved surfaces are irregularly changed. For this reason, the tangent line changes discontinuously at the joint portion of the small curved surface and is not smooth. For this reason, the focal lengths of the lenses formed by the individual small curved surfaces j1 to j6 and j1 'to j6' are the same for all the small lenses, and the microlens array surface C 'exhibits uniform lens characteristics everywhere on the entire screen.

However, a relatively large distortion occurs at a portion where the tangent changes rapidly. In order not to feel this distortion as a distortion, the size of each small lens is limited to the same size as the pixel of the display image, or in some cases, about several times the size of the pixel. When this size is reached, the image of each small lens can be regarded as a new pixel of the entire image, and the distortion inside the pixel is not perceived as distortion. On the other hand, even if the area of the small lens constituting the microlens array surface C ′ is reduced as described above, the three-dimensional effect can be exerted, and the Frennel lens surface surfaces A ′ and B ′ and the microlens array surface C ′ Can act synergistically and feel a three-dimensional effect more strongly.
In addition, since the width | variety of the small lenses j1-j6 and j1'-j6 'which comprise micro lens array surface C' is irregular, generation | occurrence | production of a moire fringe can be reduced.

Next, a third embodiment will be described in detail with reference to the drawings.
The device configuration of the display device of the third embodiment is the same as that of the display device of the first embodiment. The difference is in the curved lens.

In the third embodiment, both the outer front surface and the rear outer surface of the curved lens are Frennel lens surfaces, as in the first and second embodiments. However, both the front and back Frennel lens surfaces in the first embodiment change only in the left-right direction of the eye, and in the second embodiment, both the front and back Frennel lens surfaces are in the eye. In the third embodiment, the front Frennel lens surface changes only in the vertical direction of the eye, and the back Frennel lens surface changes in the right and left direction of the eye. It only changes with direction.
The microlens array surface is also sandwiched between both Frennel lens surfaces as in the first and second embodiments, but the configuration of the Frennel lens surface and the configuration of the microlens array surface are different. .

The curved lens according to the third embodiment will be described in detail with reference to FIG. 7, FIG. 8, and FIG.
FIG. 7 is a perspective view conceptually showing the configuration of the curved lens 10.
8 and 9 show a part of a vertical sectional view and a part of a horizontal cut surface of the curved lens 10 according to the display device of the third embodiment, respectively. The positions and directions of the cut surfaces in the vertical sectional view and the horizontal sectional view are the same as those of the vertical cut surface and the horizontal cut surface described in the first embodiment.

First, the outline of the configuration of the curved lens 10 will be described with reference to FIG.
Each of the elements A1 "to A4" and B1 "to B4" (the figure) shows that the back outer surface A "facing the display image 11 and the outer surface B" facing the opposite observer are Frennel lens surfaces. 8, see FIG. 9). Here, the number of elements is limited, and the elements B1 "to B4" are arranged in the y direction on the outer surface B ", and the elements A1" to A4 "are arranged in the x direction on the outer surface A". In fact, a number of elements having a narrower width are arranged. Accordingly, the gap between the steps is also narrowed.

  The Frennel lens surface of the outer surface A ″ is a boundary surface between the member 40 ′ and air, and the Frennel lens surface of the outer surface B ″ is a boundary surface between the member 41 ′ and air. There is also a lens surface in a portion 42 ′ (schematically shown by a thick line in FIG. 7) sandwiched between the member 40 ′ and the member 41 ′. This portion 42 ′ is an adhesive 43 ′, and microlens array surfaces C ″ and D ″ exist on the boundary surface between the adhesive 43 ′ and the member 40 ′ and on the boundary surface between the adhesive 43 ′ and the member 41 ′. A large number of small lens surfaces are arranged on the microlens array surfaces C ″ and D ″. These microlens array surfaces C ″ and D ″ are not shown in detail in FIG. 7, but will be described in detail in FIG.

The curved lens will be described in more detail with reference to FIGS.
In FIG. 8, the outer surface A ″ of the member 40 ′ is a Frennel lens surface, and the outer surface B ″ of the member 41 ′ is a Frennel lens surface. A surface C ″ opposite to the outer surface A ″ of the member 40 ′ is a surface forming a microlens array surface. Further, a surface D ″ opposite to the outer surface B ″ of the member 41 ′ is also a surface that forms the microlens array surface. Both the plane C ″ and the plane D ″ are shown as straight lines because the plane does not change in the y direction. The member 40 ′ and the member 41 ′ are joined by an adhesive 43 ′. Note that the refractive index of the adhesive 43 ′, the member 40 ′, and the member 41 ′ is appropriately selected so that the focal length of the small lens on the microlens array surface is substantially equal to the focal length of the Frennel lens surface. .

A generative surface of the Frennel lens surface B ″ is indicated by a thick dotted line as b ″. The lens surfaces B1 "to B4" of the elements constituting the Frennel lens surface B "correspond to the elements b1" to b4 "of the generating surface b", respectively. The mother curved surface b ″ is a single convex surface that does not change in the x direction perpendicular to the paper surface, and changes the thickness of the lens that hits the z direction only in the y direction. Such a mother curved surface b ″. A typical example of this is a cylindrical surface. Here, the central axis is a cylindrical surface perpendicular to the paper surface. Accordingly, the Frennel lens surface B ″ functions as a convex lens.
The elements B1 "to B4" constituting the Flennel lens surface B have a uniform width, that is, an arrangement pitch.

Next, the configuration of the Fresnel lens surface A ″ and the microlens array surface will be described in detail with reference to FIG.
In FIG. 9, the outer surface A ″ of the member 40 ′ is a Frennel lens surface, and the outer surface B ″ of the member 41 ′ is also a Frennel lens surface. A surface C ″ opposite to the outer surface A ″ of the member 40 ′ and a surface D ″ opposite to the outer surface B ″ of the member 41 ′ are surfaces that form a microlens array surface.

First, the microlens array surfaces of the surface C ″ and the surface D ″ will be described.
The small lens on the microlens array surface C ″ differs depending on whether it is a concave lens or a convex lens depending on the refractive index of the member 40 ′ and the adhesive 43 ′ and the curvature of the small lens, and the focal length also differs. The small lens on the lens array surface D ″ also has the same difference depending on the refractive index of the member 41 ′ and the adhesive 43 ′ and the curvature of the small lens.

  It is clear that the small lenses of the microlens array surfaces of the surfaces C "and D" are alternately arranged with concave lenses and convex lenses, and the microlens array surface C "has small convex lenses k1 to k8 indicated by bold lines and a small concave lens k1. The lens surfaces of these small lenses k1 to k8 and k1 ′ to k8 ′ are cylindrical surfaces having a central axis parallel to the y direction, which is a direction perpendicular to the paper surface, and have a curvature. The radii are all equal, and the central angles of the lens surfaces that are circular arcs are also equal, so the small convex lenses k1 to k8 and the small concave lenses k1 'to k8 are smooth at the junction of these small lenses k1 to k8, k1' to k8 '. In addition, since all the small lenses have the same radius of curvature, they have the same focal length.

  On the microlens array surface D ″, small convex lenses s1 and s2 indicated by bold lines and small concave lenses s1 ′ and s2 ′ are alternately arranged. The lens surfaces of these small convex lenses s1 and s2 and small concave lenses s1 ′ and s2 ′ are as follows. A cylindrical surface having a central axis parallel to the y direction, which is a direction perpendicular to the paper surface, has the same radius of curvature, and all the central angles of the lens surfaces that are arcs, so these small lenses s1 to s2, s1 ′. The convex lenses s1 to s2 and the concave lenses s1 ′ to s2 ′ are in smooth contact with each other at the joint portion of ˜s2 ′, and the small lenses have the same radius of curvature and therefore have the same focal length.

  The small lenses s1 to s2, s1 ′ to s2 ′ constituting the microlens array surface D ″ have a larger radius of curvature than the small lenses k1 to k8 and k1 ′ to k8 ′ of the microlens array surface C ″, and the arrangement pitch Is also big. That is, the small lens on the microlens array surface D ″ is wider than the small lens on the microlens array surface C ″.

In the third embodiment described above, two microlens array surfaces C ″ and D ″ exist between two Frennel lens surfaces A ″ and B ″.
The two microlens array surfaces C ″ and D ″ are small convex lenses k1 to k8 and s1 to s2 and small concave lenses k1 ′ to k8 ′ having areas sufficiently smaller than the area of the Frennel lens surfaces A ″ and B ″, respectively. , S1 ′ to s2 ′ are alternately arranged, and the difference between the two microlens array surfaces C ″ and D ″ is that the extent of the small lens is different. These two microlens array surfaces C ″ and D ″ have the same lens characteristics by changing the refractive indexes of the members 40 ′ and 43 ′ and 41 ′ and 43 ′ on both sides of the boundary forming the surfaces C ″ and D ″, respectively. To.

Next, the Frennel lens surface will be described.
One F ″ lens surface A ″ changes in the x direction, i.e., the left-right direction of the eye, and does not change in the y direction, i.e., the up-and-down direction of the eye. "" Is a surface that changes in the y direction, that is, the vertical direction of the eye, and does not change in the x direction, that is, the left and right direction of the eye. Both of the mother curved surfaces a ″ and b ″ of the two Frennel lens surfaces A ″ and B ″ form a single smooth convex surface extending over the entire area of the curved lens 10.

In FIG. 9, the outer surface B ″ of the member 41 ′ is a Frennel lens surface, but is shown by a straight line because the surface does not change in the x direction.
The outer surface A ″ of the member 40 ′ is a Fresnel lens surface, and the surface changes with respect to the x direction. Therefore, the Fresnel surface A ″ is shown as a stepped surface.
A generative surface of the Frennel lens surface A ″ is indicated by a thick dotted line as a ″. The lens surfaces A1 "to A4" of the elements constituting the Frennel lens surface A "respectively correspond to the elements a1" to a4 "of the generating curved surface. The generating curved surface a" does not change with respect to the y direction and is in the x direction. Is a single convex surface in which the thickness of the lens corresponding to the z direction changes only. The generating surface a ″ is a cylindrical surface whose central axis is perpendicular to the paper surface. Therefore, the Fresnel lens surface A ″ functions as a convex lens.

  The widths of the elements A1 "to A4" constituting the Frennel lens surface A ", that is, the arrangement pitch of the elements differ from element to element. These elements have a plurality of types having different widths. They are randomly selected and arranged in order.

The configuration of the third embodiment has been described above. The operation will be described below.
In the third embodiment, as in the first and second embodiments, a microlens array surface C ″, D ″ is sandwiched between two Frennel lens surfaces A ″, B ″. Moreover, the two Frennel lens surfaces A ″ and B ″ are lens surfaces having a large expanse equivalent to a single convex lens and are both outer surfaces in contact with air. The microlens array surfaces C ″ and D ″ have small convex surfaces k1 to k8 and s1 and s2 and small concave surfaces k1 ′ to k8 ′ and s1 ′ to s2 ′, each having a sufficiently small area as compared with the area of the curved lens 10. The boundary surfaces of the solid members having refractive indexes that are relatively similar to each other are used in the alternately arranged lens surfaces. For this reason, as in the first and second embodiments, the Frennel lens surfaces A ″, B ″ and the microlens array surfaces C ″, D ″ are stacked in multiple layers to synergize the function of expressing both stereoscopic effects. As the distortion increases, the distortion of the entire screen is reduced to a small distortion limited to a small range, and it is avoided that the distortions emphasize each other by making the spread range of both different.

  However, in this third embodiment, the changing directions of the two Frennel lens surfaces A ″ and B ″ are orthogonal to each other, one A ″ is horizontal and the other B ″ is vertical. This is different from the first embodiment in which both are in the horizontal direction or the second embodiment in which both are in the vertical direction.

Therefore, if the lens characteristics of both Frennel lenses are made to be the same, the image viewed through the curved lens can be enlarged or reduced to the same degree in both orthogonal directions, and can be seen as an image with little distortion. Further, both the Frennel lenses A ″ and B ″ can exhibit a three-dimensional effect, and these act together to produce a stronger three-dimensional effect.
In addition, since the curvature of each Frennel lens surface can be reduced compared to the case where the same degree of stereoscopic effect is realized with a single Frennel lens surface, it is possible to use a curved lens with a large effective area and a large screen. Can make a display device. Further, since the curvatures of the individual Frennel lens surfaces A ″ and B ″ can be reduced, the Frennel lens surface A ″ when the widths of the elements A1 ″ to A4 ″ constituting the Frennel lens surfaces A ″ and B ″ are equal. , B ″, the height of the side wall formed at the boundary of the elements can be reduced. As a result, moire fringes can be reduced. Further, when the height of the side wall of the step is made equal, the width of the element, that is, the gap between the steps can be increased, and the creation of the Frennel lens surface becomes easy.

  In the third embodiment, the Frennel lens surface A ″ has elements A1 ″ to A4 ″ whose widths are irregularly arranged in a horizontal direction, and the Frennel lens surface B ″ has the same width as the elements B1 ″ to B4. "Are arranged vertically. This is because the arrangement of display pixels that display an image in color, such as a TV receiver, is arranged while changing in the horizontal direction from red, green, and blue, and the pixels of each color are arranged in a straight line with almost no gap in the vertical direction. This is a configuration assuming that the Since the display pixels are arranged in the vertical direction with almost no gap, the elements on the surface of the Frennel lens surface are regularly arranged and moiré fringes hardly occur. However, when red is taken as an example in the horizontal direction, the green and blue portions become invalid gaps and invalid zones, so the elements of the Frennel lens surface are irregularly arranged to reduce the occurrence of moire fringes.

The microlens array surface is a single lens surface in the first and second embodiments, but in this third embodiment, the microlens array surface has a two-layer structure.
The small convex surfaces k1 to k8, s1 and s2 and the small concave surfaces k1 ′ to k8 ′ and s1 ′ to s2 ′ that form the microlens array surfaces C ″ and D ″ have different spreading areas.
Accordingly, the stereoscopic effect generated on the microlens array surfaces C ″ and D ″ can be obtained by the effect of both effects, thereby obtaining a stronger stereoscopic effect. At this time, since the ranges of distortion generated in the small lenses k1 to k8, k1 ′ to k8 ′ and s1 to s2, s1 ′ to s2 ′ of the microlens array surfaces C ″ and D ″ are different, they do not strengthen each other. The stereoscopic effect can be enhanced without greatly degrading the image quality.

  As described above, in the first to third embodiments, the microlens array surface has one layer or two layers as an example, but may be composed of more layers. At that time, by changing the spread area of the small lens on the microlens array surface for each layer, the range of distortion generated in each layer can be changed, and deterioration of image quality can be prevented from intensifying.

  In addition, although the configuration of the microlens array surface has been changed in each embodiment, it is obvious that the microlens array surface can be interchanged with each other in other embodiments.

In the above embodiment, the microlens array surface has been described as the boundary surface with the adhesive, but is not limited to the adhesive, and may be a boundary surface between solids having different refractive indexes. This is because, unlike a boundary surface with air, a curved surface having a large curvature can be used as a lens surface having a relatively large focal length. The solid includes a flexible member and the like, and is a member excluding gas and liquid.
In addition, the microlens array surface portion may be formed by stacking layers of members having different refractive indexes in multiple layers to form a microlens array surface having a desired refractive index ratio.

  The small lens on the microlens array surface of the embodiment shown above is a cylindrical surface lens whose lens surface changes in the horizontal direction and does not change in the vertical direction, but a cylinder that changes in the vertical direction or oblique direction. The surface may be sufficient, and the case where a lens with a short small area is arranged in both the vertical and horizontal directions may be used. Of course, the area of each small lens may be different. In short, convex lens surfaces and concave lens surfaces, which are small lenses, may be arranged alternately.

Next, a fourth embodiment will be described in detail with reference to the drawings.
The device configuration of the display device of the fourth embodiment is the same as that of the display device of the first embodiment. The difference is in the curved lens.

The curved lens according to the fourth embodiment will be described in detail with reference to FIGS.
FIG. 10 is a perspective view conceptually showing the configuration of the curved lens 10 and shows a part of the curved lens.
FIG. 11 is a horizontal cut surface showing the curved lens 10 according to the display device of the fourth embodiment. The position and direction of the horizontal cut surface are the same as the position and direction of the horizontal cut surface described in the first embodiment.

First, the outline of the configuration of the curved lens 10 will be described with reference to FIG.
In the fourth embodiment, small lenses are arranged on a curved surface similar to the Frennel lens surface. The back surface C ″ ′ that faces the display image 11 of the member 50 having a refractive index n1 ′ and the front surface D ″ ′ that faces the side facing the observer are small convex surfaces t, w having small areas, respectively. The small concave surfaces t ′ and w ′ are microarray surfaces that are alternately arranged along the arrangement surfaces u and v (u refer to FIG. 11, v is not shown) each having the shape of a Frennel lens surface. The back surface C ″ ′ is a surface in which small curved surfaces w and w ′ are arrayed along the array surface v. The array surface v changes only in the vertical direction of the eye, and the front surface D ″ ′ is a small surface t, In the plane in which t ′ is arranged along the arrangement plane u, this arrangement plane u changes only in the left-right direction of the eye.

One surface of the member 50 is a back surface C ″ ′ composed of small curved surfaces w and w ′, and the other surface is a front surface D ″ ′ composed of small curved surfaces t and t ′. The difference between the small curved surfaces w and w ′ on the back surface C ″ ′ and the small curved surfaces t and t ′ on the front surface D ″ ′ is the width of each curved surface, that is, the arrangement pitch. The small curved surfaces w and w ′ on the back surface C ″ ′ have a larger spread area as curved surfaces than the small curved surfaces t and t ′ on the front surface D ″ ′.
The back and front surfaces of the member 50 having a refractive index n1 ′ are covered with a member 51 having a refractive index n2 ′ and a member 52 having a refractive index n3 ′, respectively. The member 51 and the member 52 fill the depressions by the small curved surfaces w, w ′, t, and t ′, respectively, and form smooth surfaces having substantially the same shape as the arrangement surfaces v and u of the small curved surfaces.

  The surface A "" of the member 51 in contact with air and the surface B "" of the member 52 in contact with air have almost the same shape as the arrangement surfaces v and u of the small curved surfaces of the surfaces C "" and D "", respectively. Accordingly, the surface A "" and the surface B "'can be regarded as a Frennel lens surface having the small curved surface arrangement surfaces v and u as a mother curved surface. The small curved surfaces w, w ′, t, and t ′ that form the surface C ″ ′ that is the boundary between the member 50 and the member 51 and the surface D ″ ′ that is the boundary between the member 50 and the member 52 are small lenses, respectively. The surface C ″ ′ and the surface D ″ ′ are microlens array surfaces.

The curved lens will be described in more detail with reference to FIG. 11 which is a horizontal sectional view.
The surface D ″ ′ of the member 50 is a small convex surface T and a small concave surface having a sufficiently small area compared to the spreading area of the curved lens 10 on a virtual surface u that spreads to cover the entire surface of the curved lens 10 with a single convex surface. The virtual surfaces u on which the small curved surfaces T and T ′ are arranged are cut by the cut surfaces arranged at a constant pitch h1, and the cut elements are arranged in parallel. In the figure, the cut surface is indicated by a dotted line.

  In addition, the virtual surface u is indicated by a thick dotted line, and the small convex surface T and the small concave surface T ′ are alternately arranged along the virtual surface u. The virtual plane u is a cylindrical surface having a central axis parallel to the y direction. The curved surface changes with respect to the x direction of the xy plane, which is the spreading surface of the curved lens 10, and the y direction perpendicular to the paper surface is different. It does not change. The small convex surface t and the small concave surface t ′ that have been translated are not changed in the y direction, and the lens thickness is changed in the z direction with respect to the x direction. The change with respect to the x direction is shown in the horizontal sectional view of FIG.

  On the other hand, the surface C ″ ′ which is opposite to the surface D ″ ′ of the member 50 is formed on an imaginary surface v (not shown) which spreads over the entire surface of the curved lens 10 with a single convex surface. A cut surface in which small convex surfaces W and small concave surfaces W ′ having a sufficiently small area compared to the spread area are alternately arranged, and virtual surfaces v on which these small curved surfaces W and W ′ are arranged are arranged at a constant pitch h2. The cut elements are arranged in parallel by moving the cut elements. An overview of these situations is shown in FIG.

The virtual surface v is a cylindrical surface having a central axis parallel to the x direction. The curved surface does not change with respect to the x direction of the xy plane, which is the spreading surface of the curved lens 10, and changes with respect to the y direction. It is. The small convex surface and the small concave surface of an elongated cylindrical surface having a straight axis are arranged while being bent along the virtual surface v while being parallel to a surface perpendicular to the x axis.
Since the virtual surface v is a curved surface that changes in the y direction, the small convex surface W and the small concave surface W ′ arranged along the virtual surface v also change in the y direction. Further, the small convex surface W and the small concave surface W ′ aligned with the virtual surface v change with respect to the x direction on the horizontal plane (appears as a curved surface composed of the small convex surface w and the small concave surface w ′). The state of the change in the x direction is shown in the horizontal sectional view of FIG. As is clear from the above description, the curved surfaces of the small convex surface w and the small concave surface w ′ change in both the x direction and the y direction.

When the difference between the surface C ″ ′ and the surface D ″ ′ is arranged in the direction in which the small curved surfaces are arranged, the small curved surfaces t and t ′ that are elongated cylindrical surfaces are arranged in the direction in which the virtual surface u changes, or the small curved surfaces w and w The difference is whether 'is arranged in a direction perpendicular to the direction in which the virtual plane v changes, and in which there is no change.
The surface C ″ ′ and the surface D ″ ′ of the member 50 are covered with the member 51 and the member 52, respectively, and when the surface of the member corresponding to each element is translated and joined, the small curved surfaces W, W ′ and T, T ′ The virtual planes v and u are arranged. Accordingly, the outer surface A ″ ′ of the member 51 and the outer surface B ″ ′ of the member 52 can be regarded as a Frennel lens surface having the virtual surface v and the virtual surface u as the mother curved surface, respectively.

The surface C ″ ′ of the member 50 having the refractive index n1 ′ has a refractive index relationship with the member 51 having the refractive index n2 ′, and the small concave surface and the small convex surface are either convex lenses or concave lenses, and the small convex lens and the small concave lens are alternately arranged. The members 50 and 51 are appropriately selected in refractive index so that the focal length of the small lens on the microlens array surface is substantially equal to the focal length of the Frennel lens surface. It is.
The surface D ″ ′ of the member 50 having the refractive index n1 ′ also has a refractive index relationship with the member 52 having the refractive index n3 ′, so that the small concave surface and the small convex surface are either convex lenses or concave lenses. The member 52 is arranged in an alternating manner, and the member 52 is compared with the refractive index of the member 50 so that the focal length of the small lens on the microlens array surface is substantially equal to the focal length of the Frennel lens surface. The refractive index is selected appropriately.

  The small lenses t and t ′ on the surface D ″ ′ are arranged side by side on the curved surface, so that the characteristics as a lens of the microlens array are strengthened. The individual small lenses on the surface C ″ ′ are arranged in a straight line. However, since the individual small lenses w and w ′ are bent along the arrangement plane v, the characteristics of the microlens array as a lens are enhanced.

As is clear from the above description, microlens array surfaces C ″ ′ and D ″ ′ obtained by alternately arranging small convex lenses t and w and small concave lenses t ′ and w ′ are Frennel lens surfaces A ″ ′ and B ′. The small lenses w, w ′ and t, t ′ of the microlens array surfaces C ″ ′, D ″ ′ are tilted with the location, and the characteristics as the lens change with the location.
As a result, a third difference is generated in the retinal images of the right eye and the left eye based on the microlens array surfaces C ″ ′ and D ″ ′, the difference due to the Frennel lens surfaces A ″ ′ and B ″ ′, and the microlens array. The small convex surfaces t and w of the surfaces C ″ ′ and D ″ ′ overlap with the individual differences between the small concave surfaces t ′ and w ′, and the three-dimensional effect is expressed more strongly.
Further, since the microlens array surfaces C ″ ′ and D ″ ′ are smooth together with the Frennel lens surfaces A ″ ′ and B ″ ′, the image seen through the curved lens 10 is not abruptly distorted, and is easy to see with little discomfort. It can be seen as an image.

  Furthermore, since the microlens array surfaces C ″ ′, D ″ ′ are the boundary surfaces that contact the solid members 50, 51, 50, and 52, the Frennel lens surfaces A ″ ′, B ″ ′ having a large curvature in contact with air. And the lens characteristics of the small curved surfaces w, w ′ and t, t ′ of the microlens array surfaces C ″ ′, D ″ ′ can be made comparable. A curved lens having an integral structure can be configured without using a separate part, and a display device having a strong stereoscopic effect can be obtained.

  In the first to fourth embodiments, there are two Frennel lens surfaces, and the microlens array surface is sandwiched between the two Frennel lens surfaces. A plurality of the above may be used. A structure in which at least two of the plurality of Fresnel lens surfaces are selected and the microlens array surface is sandwiched may be combined with the remaining Fresnel lens surfaces. In the case where there are three Frennel lens surfaces, it is possible to divide the lens into two groups each having two groups, and sandwich the microlens array surface between each group, and combine these to form one curved lens. At that time, the microlens array surface can be sandwiched only by one set, and the other set can not be sandwiched.

  In the fourth embodiment, the three-dimensional effect is enhanced by the effect that the surface of the microlens array is curved. For this reason, a single Flennel lens surface can be used, and a configuration in which the Frennel lens surface and the microlens array surface are one is also practical.

  In the first to fourth embodiments, the way of combining the two Frennel lens surfaces is changed. The curved surface changes in the same direction and in the horizontal direction, in the vertical direction, and in the orthogonal direction, one is in the horizontal direction and the other is in the vertical direction. Limiting the direction of the curved surface to one direction makes it easier to create a lens curved surface, and if the limited direction of change is aligned with the left-right direction of the eye or the vertical direction of the eye, there is no sense of discomfort without skewing. However, the direction of the lens curved surface can be freely changed. In this case, the effective area can be expanded, the stereoscopic effect can be enhanced, and the distortion can be further reduced. . In particular, if the curved surface changes greatly in one specific direction and changes little in the other direction, if only the direction that changes roughly is considered as the change direction, this direction can be adjusted to the left or right or up and down direction of the eye. Can greatly reduce the sense of discomfort with distortion.

In the first to fourth embodiments, the Frennel lens surfaces are all convex lenses, but may be concave lenses. However, the front and back Frennel lens surfaces must both be convex lenses or concave lenses. Otherwise, the effects may be offset, or adverse effects such as greatly changing the vertical and horizontal magnification of the image may be brought about.
In each of the drawings for explaining the first to fourth embodiments, the small convex lens and the small concave lens on the microlens array surface are drawn smaller than the width of the element on the Frennel lens surface. In some cases, the small concave lens is larger than the width of the element.

Next, a fifth embodiment will be described.
The device configuration of the display device of the fifth embodiment is the same as that of the display device of the first embodiment. The difference is in the curved lens.
The curved lens in the fifth embodiment also has a Fresnel lens surface and a microlens array surface. By reducing the lens characteristics of the Frennel lens surface at the central portion and small at the peripheral portion, distortion at the peripheral portion is reduced, and the effective area as a lens is expanded.
In the first to fourth embodiments, all of the Frennel lens surfaces are cylindrical surfaces. For cylindrical and spherical lenses, the curvature or radius of curvature is the same at all locations. Nevertheless, the lens characteristics increase as the distance from the optical axis increases. This is because the lens curved surface is inclined. For this reason, the image is greatly distorted at the peripheral portion.

Light that reaches the curved lens from a sufficiently far point that correctly faces the curved lens can be regarded as approximately parallel to the optical axis. The optical axis passes through the most protruding point of the curved surface on the convex surface and the most retracted point on the concave surface. These points are the vertices. When there is no vertex on the surface of the Frennel lens, the optical axis is outside the effective area of the phase lens.
On the convex lens surface, light traveling parallel to the optical axis is refracted by the lens surface and collected at one point. On the concave lens surface, the light traveling parallel to the optical axis is refracted by the lens surface and diffuses as if radiated from one point. The point that gathers at one point or the point that radiates from one point is the focal point, and the distance from the lens curved surface to this focal point is the focal length. The focal points are on both sides of the lens curved surface.
In the vicinity of the apex of the lens, the position of the focal point and the focal length can be regarded as being approximately constant. Under this premise, the lens law is widely known, and the characteristics of the lens are described by the curvature or the radius of curvature.

  In the description of the first embodiment, the outline has been approximately described by applying a well-known lens equation under this premise. However, the Frennel lens surface of the curved lens used in the display device has a wide spreading surface, and the lens surface tilts with respect to the optical axis at each location. As a result, even with a lens curved surface with the same curvature and the same radius of curvature, the focal position for each location And focal length are different. However, it can be regarded as approximately constant in a narrow area with limited location. Such local focus and focal length are the local focus and the local focal length. This local focal length cannot be simply expressed by only the radius of curvature of the lens surface, but also depends on the inclination of the lens curved surface with respect to the optical axis. The position of the local focus varies from place to place, and the local focal length also varies from place to place. The magnification of the image of the local portion can be determined using a well-known lens equation using the local focal length.

  The curved surface shape of the Frennel lens surface can also be determined so that the local focal length is constant regardless of the location. Such a curved surface has a shape in which the curve changes less than the arc as it moves away from the apex as compared to an arc representing a cylindrical surface in a sectional view. Such a curved surface cannot be expressed by a simple mathematical expression, but can be determined relatively easily.

  At the peripheral edge of the curved lens, there is a sense of incongruity that the straight line that is the outermost frame of the display image looks distorted, especially when viewed from an oblique direction. These distortions can be mitigated by making the local focal length of the peripheral portion of the Frennel lens surface larger than the local focal length of the central portion with almost no loss of stereoscopic effect.

  At the center of the curved lens that greatly contributes to the appearance of stereoscopic effect, the lens surface is strongly curved and the local focal length is small, so that a large stereoscopic effect appears in the overall image. At the peripheral part that does not contribute to the appearance of stereoscopic effect, the curvature of the lens surface is weakened, and the image enlargement / reduction ratio is reduced, resulting in less image distortion and the outermost frame of the display image when viewed from an oblique direction. The distortion of a certain straight line can also be reduced. Further, since it is possible to eliminate an unnecessary large curvature at the peripheral portion of the Frennel lens surface, the effective area of the curved lens can be widened and a large display device can be realized.

  In the fifth embodiment, the form in which the curvature of the Frennel lens surface, that is, the curvature of the generating surface changes depending on the location has been described. As described above, the main curved surface of the Frennel lens surface does not need to be a curved surface having one curvature, and is a smooth convex surface in which two or more convex surfaces having different curvatures are connected, or a smooth concave surface in which two or more concave surfaces having different curvatures are connected. I need it.

  Regarding the display devices in the first to fourth embodiments, the positional relationship between the curved lens 10 and the display image 11 will be described. The focal length of the curved lens 10 is determined in consideration of the characteristics of each lens curved surface constituting the curved lens 10. The Frennel lens surface is relatively wide, and the small convex lens and the small concave lens on the micro lens array surface are relatively small. Therefore, the local focal length varies from place to place. Since the visible image must naturally be an erect image, it is necessary to place the lens surface of the curved lens 11 closer to the display image 11 than the local focal length. In order to reduce image distortion, it is necessary to bring the curved lens closer to the display screen 11. On the other hand, the stereoscopic effect becomes stronger as the curved lens is moved away from the display image and closer to the local focus. The position to be placed is determined by the balance between the degree of allowable distortion and the degree of three-dimensional appearance. However, placing it in the vicinity of the local focus is too impractical and impractical.

  The present invention can be used in a display device that displays a two-dimensional image as a stereoscopic image with a sense of depth.

1 is a perspective view of a display device according to a first embodiment of the present invention. It is a perspective view which shows notionally the structure of the curved lens in 1st Embodiment. It is drawing for demonstrating the horizontal sectional view which shows the structure of the curved surface lens in 1st Embodiment notionally, and the shape of a small lens surface. (A) is a horizontal sectional view of a curved lens, (b) is an explanatory view of a small lens surface. It is a perspective view which shows notionally the structure of the curved surface lens in 2nd Embodiment. It is a vertical sectional view which shows notionally the composition of the curved lens in a 2nd embodiment. It is a horizontal sectional view which shows notionally the composition of the curved lens in a 2nd embodiment. It is a perspective view which shows notionally the structure of the curved lens in 3rd Embodiment. It is a vertical sectional view which shows notionally the composition of the curved lens in a 3rd embodiment. It is a horizontal sectional view which shows notionally the composition of the curved lens in a 3rd embodiment. It is a perspective view which shows notionally the structure of the curved surface lens in 4th Embodiment. It is a horizontal sectional view which shows notionally the structure of the curved lens in 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Curved lens 11 Display image 12 Holding mechanism 12a Back plate 12b of holding mechanism Arm 20 of holding mechanism Member 21 constituting curved lens Member 22 constituting curved lens 22 Part 20 sandwiched between member 20 and member 21 Constructing curved lens Adhesives 40, 40 'Members 41, 41' constituting a curved lens
42 part 42 'sandwiched between member 40 and member 41 parts 43 and 43' sandwiched between member 40 'and member 41' Adhesive 50 member 51 constituting curved lens 51 member constituting curved lens 52 constituting curved lens Members A, A ', A ", A"' Frennel lens surface (outer surface of curved lens)
B, B ', B ", B"' Frennel lens surface (outer surface of curved lens)
C, C ′, C ″, C ″ ′ Micro lens array surface (boundary surface of the member)
D, D ', D ", D"' Microlens array surface (member boundary surface)
a, a ′, a ″, a ″ ′ Generating surfaces b, b ′, b ″, b ″ ′ of the Fresnel lens surface Generating surfaces A1 to A5, A1 ′ to A14 ′, A1 ″ to A4 of the Fresnel lens surface "Elements a1 to a5, a1 'to a14', a1" to a4 "constituting the Fresnel lens surface elements B1 to B5, B1 'to B14', B1" to the base surface corresponding to the elements of the Fresnel lens surface B4 "Elements that make up the Frennel lens surface
b1 to b5, b1 ′ to b14 ′, b1 ″ to b4 ″ elements of the generating surface corresponding to the elements of the Frennel lens surface i1 to i4, i1 ′ to i4 ′ small curved surface or small lens surfaces j1 to j6, j1 ′ to j6 ′ small curved surface or small lens surfaces k1 to k8, k1 ′ to k8 ′ small curved surface or small lens surfaces s1, s2, s1 ′, s2 ′ small curved surface or small lens surfaces t, t ′, w, w ′ small curved surface or Small lens surface T, T ′, W, W ′ Magnification of small curved surface m image on virtual surface
n, n1, n2, n1 ′ to n3 ′ refractive index
f Focal length d Distance from the curved surface of the displayed image r Radius of curvature of the lens surface
g Arbitrary point h of mother curved surface h Normal line at arbitrary point g of mother curved surface q Normal surface of curved lens θ Angle formed by specific direction (vertical direction) of normal h at arbitrary point g of mother curved surface e Vertices u, v Virtual planes h1, h2 on which small lenses are arranged Interval of cut planes that cut the mother curved surface

Claims (15)

  At least two or more Frennel lens surfaces having a single smooth convex surface or a single smooth concave surface as a generating surface, and areas of the first and second Frennel lens surfaces of the two or more Frennel lens surfaces A curved lens having a microlens array surface in which small convex lenses and small concave lenses having a sufficiently small area are alternately arranged.   The curved lens according to claim 1, wherein the microlens array surface is smooth.   The curved lens according to claim 1, wherein the microlens array surface is a boundary surface between two solid members having different refractive indexes, sandwiched between the first and second Frennel lens surfaces.   4. The curved lens according to claim 1, wherein a focal length of the microlens array surface is substantially equal to a focal length of the first or / and second Fresnel lens surface. 5.   The first direction in which the change of the generating surface is maximum on the first Frennel lens surface and the second direction in which the change of the generating surface is maximum on the second Frennel lens surface are approximately The curved lens according to any one of claims 1 to 4, wherein the curved lens is parallel.   The first direction in which the change of the generating surface is maximum in the first Frennel lens surface and the second direction in which the change of the generating surface is maximum in the second Frennel lens surface are approximately The curved lens according to claim 1, which is orthogonal to each other.   The interval between the steps of the first or second Frennel lens surface is irregularly arranged and / or the size or position of either the small convex lens or the small concave lens or both of the microlens array surface are irregularly arranged. The curved lens according to any one of claims 1 to 6, wherein the curved lens is formed.   A Frennel lens surface having a single smooth convex surface or a single smooth concave surface as a generating surface, and a small convex lens and a small concave lens having an area sufficiently smaller than the area of the Frennel lens surface are alternately arranged. A microlens array surface, and the microlens array surface has a step at a position corresponding to the step of the Frennel lens surface at a boundary surface between two solid members having different refractive indexes, and the Frennel lens A curved lens placed along a surface.   The curved lens according to claim 8, wherein the small convex lens and the small concave lens forming the micro lens array surface are smoothly connected except for a position corresponding to a step of the Fresnel lens surface.   The curved lens according to claim 8 or 9, wherein a focal length of the micro lens array surface is substantially equal to a focal length of the Frennel lens surface.   9. The steps of the Fresnel lens surface are irregularly arranged and / or the microlens array surface is irregularly arranged in either one or both of the small convex lens and the small concave lens. The curved lens according to any one of claims 10 to 10.   The angle formed by a normal line on the Frennel lens surface and a straight line in a specific direction is either an acute angle or an obtuse angle at any point on the Frennel lens surface. The curved lens described.   A Frennel lens surface having either a single smooth convex surface or a single smooth concave surface as a generating surface, and small convex lenses and small concave lenses are alternately arranged, and the small convex lens and the small lens adjacent to each other are arranged. A part or all of the junction points with the concave lens are in a discontinuous junction state where the tangents of the curved surfaces of both lenses do not coincide, and the short side of the small convex lens and the small concave lens is one of the short sides of the Frennel lens surface. A curved lens having a microlens array surface of / 500 or less.   The curved lens according to any one of claims 1 to 13, wherein a local focal length of a peripheral portion of the Frennel lens surface is larger than a local focal length of a central portion.   The positional relationship between the curved lens according to any one of claims 1 to 14, a two-dimensional display image disposed to face the curved lens, and the two-dimensional display image and the curved lens is maintained. A display device comprising at least one or both of holding mechanisms.