JP2015069148A - Linear fresnel lens sheet and transmissive display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Fresnel lens sheet with a plurality of Fresnel lens sections, which smoothly displays images formed by image light and can be manufactured inexpensively.SOLUTION: A linear Fresnel lens sheet 3 has a plurality of integrally formed linear Fresnel lens sections 13, each of which having an optical center O.

Description

  The present invention relates to a linear Fresnel lens sheet that emits image light projected from a light source to the light output side, and a transmissive display device including the linear Fresnel lens sheet.

  In the rear projection type video display device, a transmission type screen that displays video light that is enlarged and projected is used. The transmissive screen disclosed in Patent Document 1 includes a linear Fresnel lens sheet that deflects image light enlarged and projected from a light source so as to be substantially parallel light, and a visual field that diffuses image light emitted from the linear Fresnel lens sheet. And a diffusion sheet that widens the corners. Among these, the linear Fresnel lens sheet has a linear Fresnel lens surface in which a plurality of lens surfaces are arranged along a predetermined direction. Typically, the linear Fresnel lens surface is disposed on the light output side surface.

JP 2000-292864 A

  In recent years, attempts have been made to reduce the distance between the light source and the transmissive screen to make the rear projection type image display device compact. When the distance between the light source and the transmissive screen is shortened, the incident angle of the image light incident on the lens surface at a position far away from the light source is increased. When the incident angle of the image light incident on the lens surface increases, the reflectance at the lens surface increases, and the amount of light transmitted through the lens surface decreases. As a result, there is a problem in that an image formed by video light appears dark in a region that is greatly separated from the light source.

  Therefore, the present inventor divided the image light so that it is projected from a plurality of light sources in order to suppress the incident angle of the image light to the lens surface, and has a Fresnel lens portion having a number corresponding to each image light. An attempt was made to make a sheet. Here, the Fresnel lens sheet was produced by arranging a plurality of single-sheet circular Fresnel lens layers and bonding adjacent circular Fresnel lens layers.

  However, in the above-described method for producing a Fresnel lens sheet, a plurality of sheet-like circular Fresnel lens layers cannot be accurately positioned, and an image formed by video light from adjacent light sources can be displayed smoothly. Can not.

  The present invention has been made in view of these points, and provides a Fresnel lens sheet having a plurality of Fresnel lens portions that can smoothly display an image formed by video light and can be easily manufactured. The purpose is to do.

The first linear Fresnel lens sheet according to the present invention is:
It has a plurality of linear Fresnel lens parts molded in one piece,
Each linear Fresnel lens part has an optical center.

In the first linear Fresnel lens sheet according to the present invention, each linear Fresnel lens part has a plurality of lens surfaces arranged along the first direction,
The plurality of linear Fresnel lens portions may be arranged side by side along the first direction.

The second linear Fresnel lens sheet according to the present invention comprises a plurality of linear Fresnel lens parts formed integrally,
Each linear Fresnel lens unit includes a first lens surface group, and a second lens surface group disposed on one side of the first lens surface group,
The first lens surface group includes a plurality of first lens surfaces that are inclined to the same side with respect to the normal direction to the sheet surface of the linear Fresnel lens sheet,
The second lens surface group may include a plurality of second lens surfaces that are inclined to a side opposite to the first lens surface with respect to a direction normal to the sheet surface of the linear Fresnel lens sheet.

In the second linear Fresnel lens sheet according to the present invention, the plurality of first lens surfaces and the plurality of second lens surfaces are each arranged along a first direction,
The plurality of linear Fresnel lens portions may be arranged side by side along the first direction.

  In the first or second linear Fresnel lens sheet according to the present invention, the lengths of the linear Fresnel lens portions in the first direction may be the same.

  In the first or second linear Fresnel lens sheet according to the present invention, the plurality of linear Fresnel lens portions may be formed identical to each other.

  A transmissive display device according to the present invention includes a linear Fresnel lens sheet having any one of the above characteristics.

The transmissive display device according to the present invention further includes a light source having a plurality of projection surfaces for projecting image light onto the linear Fresnel lens sheet,
Each projection surface may project image light onto a corresponding linear Fresnel lens unit.

Alternatively, the transmissive display device according to the present invention further includes a plurality of light sources having a projection surface for projecting image light onto the linear Fresnel lens sheet,
The projection surface of each light source may project image light onto the corresponding linear Fresnel lens unit.

  According to the present invention, since the plurality of linear Fresnel lens portions are integrally formed, the plurality of linear Fresnel lens portions can be easily and accurately positioned. For this reason, a Fresnel lens sheet having a plurality of Fresnel lens portions can be easily manufactured, and an image formed by video light from a light source can be smoothly connected using the linear Fresnel lens sheet.

1 is a schematic perspective view showing a transmissive display device according to an embodiment of the present invention. FIG. 2 is a schematic plan view of the transmissive display device illustrated in FIG. 1. It is the schematic which expands and shows the linear Fresnel lens part of the linear Fresnel lens sheet of the transmissive display apparatus shown in FIG. It is the schematic which shows an example of the method of manufacturing the lens layer of the transmission type screen shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product. 1 to 3 are views for explaining a linear Fresnel lens sheet according to an embodiment of the present invention. 1 and 2 are a schematic perspective view and a schematic plan view, respectively, showing a transmission screen provided with a linear Fresnel lens sheet according to an embodiment of the present invention.

  As shown in FIGS. 1 and 2, the transmission screen 2 is for projecting and displaying the image light L projected from the light source 7 on the observation side. As shown in FIG. 1, the transmissive screen 2 includes a linear Fresnel lens sheet 3 that deflects the image light L projected from the projection surface 8 of the light source 7 toward the observation side so as to be substantially parallel light, and the linear Fresnel lens. And a diffusion sheet 4 that is disposed on the observation side of the sheet 3 and diffuses the image light L to emit the image light L toward a wide range of observers. The surface of the diffusing sheet 4 opposite to the linear Fresnel lens sheet 3 forms the light-emitting surface 2a of the transmission screen 2 that emits the image light L toward the observer. Such a transmission screen 2 can be used by being incorporated in the rear projection type transmission display device 1.

  As shown in FIGS. 1 and 2, the transmissive display device 1 includes a transmissive screen 2 and a plurality of projection surfaces 8 that project the image light L toward the linear Fresnel lens sheet 3 of the transmissive screen 2. A light source (video light source) 7. Among these, the light source 7 includes an image source such as an LCD or a DLP, a lamp for irradiating light to the image source, a projection lens for enlarging and projecting image light emitted through the image source, and the like.

  In such a transmissive display device 1, the image light L projected from the projection surface 8 of the light source 7 forms a predetermined projection angle with respect to the normal direction nd to the sheet surface 3 a of the linear Fresnel lens sheet 3. To the respective positions of the linear Fresnel lens sheet 3. The projection angle, which is the angle formed by the traveling direction of the light incident on the linear Fresnel lens sheet 3 with respect to the normal direction nd, changes according to the incident position on the linear Fresnel lens sheet 3. And the projection angle of the light which injects into each position of the linear Fresnel lens sheet 3 from the light source 7 can be adjusted by selecting the relative positional relationship of the light source 7 and the linear Fresnel lens sheet 3 appropriately. In the transmissive display device 1 of the present embodiment, the distance v between the linear Fresnel lens sheet 3 and the light source 7 is set to be short so as to make the entire device compact. For this reason, the projection angle of the video light L projected from each light source 7 is suppressed by projecting the video light L from the plurality of light sources 7.

  The projection angle of the image light L projected from each light source 7 is determined according to the combination with the linear Fresnel lens unit 13 described later. The images displayed by the video lights L may be the same as each other or different from each other. In particular, when images displayed by the video lights L are different from each other, one video may be displayed as a whole by combining the images displayed by the video lights L.

  Next, the transmission screen 2 will be described in detail. As described above, the transmission screen 2 includes the linear Fresnel lens sheet 3 and the diffusion sheet 4. First, the linear Fresnel lens sheet 3 will be described with reference to FIGS. 1 to 3. FIG. 3 is an enlarged view schematically showing an enlarged part of the linear Fresnel lens sheet 3 of the transmissive display device 1 shown in FIG. As shown in FIGS. 1 to 3, the linear Fresnel lens sheet 3 is for deflecting the image light L projected from the projection surface 8 of each light source 7 to the observation side so as to be substantially parallel light. The linear Fresnel lens sheet 3 includes a lens layer 10 disposed on the diffusion sheet 4 side and a base material 30 disposed on the light source 7 side with respect to the lens layer 10.

  As shown in FIG. 3, the lens layer 10 has a first surface 11 facing the diffusion sheet 4 side, and a second surface 12 facing the first surface 11 and facing the light source 7 side. A plurality of linear Fresnel lens portions 13 are disposed on the first surface 11 of the lens layer 10. Each linear Fresnel lens unit 13 deflects the image light L from the corresponding light source 7 to the observation side so as to be substantially parallel light. The plurality of linear Fresnel lens portions 13 are integrally formed. That is, as apparent from the manufacturing method described later, no seam is formed between the members constituting each linear Fresnel lens portion 13. According to such a form, since the several linear Fresnel lens part 13 can be positioned easily and accurately, the image formed with the video light L from the adjacent light source 7 can be connected smoothly.

  As shown in FIG. 3, each linear Fresnel lens portion 13 has a plurality of lens surfaces 14 arranged in a stripe shape. The linear Fresnel lens unit 13 is expected to exhibit a lens action similar to that of a convex lens with respect to incident light by a combination of a plurality of lens surfaces 14. Specifically, the linear Fresnel lens unit 13 includes a first lens surface group including a plurality of first lens surfaces 14a inclined to the same side with respect to the normal direction nd to the sheet surface 3a of the linear Fresnel lens sheet 3. 13a and a second lens surface group 13b including a plurality of second lens surfaces 14b inclined to the side opposite to the first lens surface 14a with respect to the normal direction nd. The first lens surface group 13a is disposed on one side of the second lens surface group 13b along the first direction d1, and conversely, the second lens surface group 13b is more than the first lens surface group 13a. , Arranged on the other side along the first direction d1. The plurality of first lens surfaces 14 a and the plurality of second lens surfaces 14 b constitute a plurality of lens surfaces 14 of the linear Fresnel lens sheet 3.

  In this specification, “sheet surface (film surface, plate surface)” is the same as the planar direction of the target sheet-like member when the target sheet-like member is viewed as a whole and globally. It refers to the surface to be used. In the present embodiment, the sheet surface 3a of the linear Fresnel lens sheet 3, the sheet surface of the lens layer 10, and the sheet surface of the substrate 30 are parallel to each other. In the following description, as shown in FIG. 3, the second surface 12 of the lens layer 10 is illustrated as a sheet surface 3 a of the linear Fresnel lens sheet 3.

  In addition, terms used in this specification for specifying shapes and geometric conditions, such as “parallel” and “orthogonal”, are not limited to strict meanings and cannot be distinguished by visual judgment. Interpretation will be made including errors within a range where similar optical functions can be expected as much as possible.

  The plurality of lens surfaces 14 are arranged along a first direction d <b> 1 extending in the sheet surface 3 a of the linear Fresnel lens sheet 3. That is, the plurality of first lens surfaces 14a and the plurality of second lens surfaces 14b are each arranged along the first direction d1. Each first lens surface 14a and each second lens surface 14b extend linearly in a direction intersecting the first direction d1, more specifically in a direction orthogonal to the first direction d1.

  A lens angle α, which is an angle formed by the lens surface 14 with respect to the sheet surface 3a of the linear Fresnel lens sheet 3, gradually changes along the first direction d1. Specifically, in each linear Fresnel lens unit 13, the lens angle α of any one first lens surface 14a is the second lens surface along the first direction d1 from the one first lens surface 14a. The angle is equal to or larger than the lens angle α of the other first lens surface 14a disposed in the vicinity of the group 13b. On the other hand, in each linear Fresnel lens portion 13, the lens angle α of any one second lens surface 14b is set to the first lens surface group 13a along the first direction d1 with respect to the one second lens surface 14b. The angle is equal to or larger than the lens angle α of the other second lens surface 14b disposed in proximity. Therefore, in each linear Fresnel lens portion 13, the first lens surface 14a included in the first lens surface group 13a is disposed closest to the second lens surface group 13b along the first direction d1. The lens angle α of one lens surface 14a is the smallest. Similarly, in each linear Fresnel lens unit 13, the second lens surface 14b included in the second lens surface group 13b is disposed closest to the first lens surface group 13a along the first direction d1. The lens angle α of the second lens surface 14b is the smallest.

  In each linear Fresnel lens unit 13, the optical center O is located at a position between or a boundary between the first lens surface group 13a and the second lens surface group 13b. Here, the optical center O means an optical center that exerts a lens action on incident light by a combination of a plurality of lens surfaces 14 constituting the linear Fresnel lens unit 13. In a typical linear Fresnel lens, the optical center O of each linear Fresnel lens unit 13 is located on the optical axis Ax of the linear Fresnel lens unit 13. In the illustrated example, the optical center O is the first lens surface 14a disposed closest to the second lens surface group 13b along the first direction d1 and the first lens surface most along the first direction d1. It is located on the boundary with the second lens surface 14b arranged close to the group 13a.

  The linear Fresnel lens unit 13 includes a rise surface 15 provided between two adjacent lens surfaces 14. The length of the rise surface 15 is generally determined by the pitch P of the adjacent lens surfaces 14 and the lens angle α of the lens surfaces 14. As described above, the lens angle α is larger on the lens surface 14 disposed away from the optical center O along the first direction d1 of the lens surface 14. Therefore, if the pitch P of the lens surfaces 14 is constant, among the plurality of rise surfaces 15, the rise surface 15 that is arranged further away from the optical center O along the first direction d1 is the normal direction. The length along nd becomes longer. Specifically, the rise surface 15 includes a first rise surface 15a extending between two adjacent first lens surfaces 14a, a second rise surface 15b extending between two adjacent second lens surfaces 14b, It is comprised by. The rise surface 15 is a surface on which no lens action of light is expected.

  By the way, in this Embodiment, compared with the distance v of the light source 7 and the linear Fresnel lens sheet 3, the length in the 1st direction d1 of the linear Fresnel lens sheet 3 is remarkably large. In this case, when the image light L is directly projected from the single projection surface of the single light source onto the linear Fresnel lens sheet, the image light is incident on the lens surface 14 at a position greatly separated from the light source along the first direction d1. The incident angle of L becomes considerably large. For this reason, the reflectance at the lens surface 14 at the separated position increases, and an image formed by the video light L appears dark in a region that is largely separated from the light source along the first direction d1. That is, in the general rear projection type transmissive display device 1 that uses a single projection surface of a single light source, if the distance v between the light source 7 and the linear Fresnel lens sheet 3 is shortened, the transmissive screen 2 A long length in the first direction d1 cannot be secured. In addition, when the incident angle of the image light L on the lens surface 14 increases, the lens angle α of the lens surface 14 also increases in accordance with the incident angle. In particular, when the lens angle α of the lens surface 14 exceeds 70 °, it is difficult to cut the roll-shaped mold 134 (see FIG. 4) for shaping the lens surface 14 under conditions that are mass-productive. Become. Therefore, in a transmissive display device in which the length of the linear Fresnel lens sheet 3 in the first direction d1 is significantly larger than the distance v between the light source 7 and the linear Fresnel lens sheet 3, the projection of a single light source When image light is directly projected from a surface onto a linear Fresnel lens sheet, the lens surface at a position far away from the light source cannot be molded in a mass-productive condition.

  Therefore, in the present embodiment, a plurality of linear Fresnel lens portions 13 are arranged side by side along the first direction d1. Corresponding to the arrangement of the plurality of linear Fresnel lens portions 13, the plurality of light sources 7 are arranged side by side along the first direction d1. According to such a transmissive display device 1, each light source 7 has a light source 7 as compared with a case where image light is projected from a projection surface of a single light source onto a linear Fresnel lens sheet having a single linear Fresnel lens unit. The maximum angle of the image light L projected from the projection surface 8 that is inclined in the first direction d1 with respect to the normal direction nd can be suppressed. Thereby, the reflectance in each lens surface 14 can be suppressed low, and as a result, it is possible to effectively suppress the image formed by the video light L from being viewed darkly.

  In the present embodiment, the lengths u of the linear Fresnel lens portions 13 in the first direction d1 are the same. But the length u in the 1st direction d1 of each linear Fresnel lens part 13 may mutually differ. Further, in the present embodiment, the plurality of linear Fresnel lens portions 13 are formed identical to each other. That is, each linear Fresnel lens part 13 has the same size, and the lens surface 14 of each linear Fresnel lens part 13 is also arranged in the same manner. But the some linear Fresnel lens part 13 may be formed so that it may mutually differ. Two adjacent linear Fresnel lens portions 13 are arranged with almost no gap. Specifically, the interval between two adjacent linear Fresnel lens portions 13 is 2.0 mm or less, preferably 1.0 mm or less.

  As a resin material constituting the lens layer 10 having such a plurality of linear Fresnel lens portions 13, for example, acrylate resins such as urethane acrylate and epoxy acrylate are preferably used. As an example, the refractive index of the resin material constituting the lens layer 10 is adjusted to about 1.55 to 1.65.

  Next, the base material 30 laminated on the light source 7 side of the lens layer 10 will be described. The base material 30 is provided to stably mold the linear Fresnel lens portion 13 of the lens layer 10. The base material 30 of this Embodiment is comprised as a single member, and the seam is not formed. As a material which comprises the base material 30, a PET film, an acrylic resin film, and a polycarbonate film can be used, for example. In addition, the base material 30 is selected according to the shaping method of the linear Fresnel lens surface 13, and does not necessarily need to be provided.

  Next, the diffusion sheet 4 that constitutes the transmission screen 2 together with the linear Fresnel lens sheet 3 will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the diffusion sheet 4 includes a light control layer 41, an adhesive layer 44, a light exit side diffusion layer 45, a base material 46 and a hard coat layer 47 that are arranged from the light incident side toward the light exit side. Includes in order.

  Among these, the light control layer 41 disposed closest to the linear Fresnel lens sheet 3 has a function of absorbing external light incident on the diffusion sheet 4 and increasing the contrast of the screen. In addition, the light control layer 41 of the present embodiment diffuses the image light from the linear Fresnel lens sheet 3 and emits the image light toward a wide range in the vertical direction. As a specific configuration, the light control layer 41 has a main portion 42 in which a plurality of grooves 42 a extending in the horizontal direction are formed. The plurality of grooves 42a formed in the main portion 42 are arranged side by side in the vertical direction. Each groove 42 a tapers as it is separated from the base material 46 along the thickness direction of the light control layer 41. Each groove 42a of the main portion 42 is filled with a unit optical element 43 made of a resin material. The unit optical element 43 forms an interface having a refractive index difference with the main portion 42. At least a part of the image light L incident on the light control layer 41 of the diffusion sheet 4 is reflected from the linear Fresnel lens sheet 3 by the interface, so that the image light L is emitted from the light-emitting side surface 2 a formed of the hard coat layer 47. Is diffused and emitted.

  Further, a light transmission region 42b is defined between adjacent grooves 42a formed in the main portion 42. That is, in the main part 42, the grooves 42a and the light transmission regions 42b are alternately arranged in parallel along the vertical direction. The light that passes through the light transmission region 42b does not enter the groove 42a but enters the adhesive layer 44 as it is, and enters the groove 42a and is reflected at the interface between the unit optical element 43 and the main portion 42. , And light entering the adhesive layer 44. According to such a light control layer 41, the incident image light L can be reflected and diffused at the interface between the unit optical element 43 and the main portion 42, so that the image light L is emitted in a wide range in the vertical direction. Can be made.

  Moreover, the unit optical element 43 of this Embodiment contains the light absorptive particle. Thereby, the external light which injects into the transmissive screen 2 can be absorbed effectively. For this reason, the contrast of the image displayed on the transmissive screen 2 can be improved.

  In addition, the form of the light control layer 41 is not limited to such an example, and can be widely applied as long as it has a function of absorbing external light incident on the diffusion sheet 4 and increasing the contrast of the screen. For example, the light control layer 41 may have a form in which a plurality of lenticular lenses are arranged in a predetermined direction. In this case, for example, a plurality of lenticular lenses each extending in the horizontal direction may be arranged in the vertical direction. Thus, in addition to absorbing the external light incident on the diffusion sheet 4 and increasing the contrast of the screen, the image light from the linear Fresnel lens sheet 3 is diffused and emitted to a wide range in the vertical direction. You can also. Alternatively, when importance is attached to the viewing angle in the horizontal direction, a plurality of lenticular lenses each extending in the vertical direction may be arranged side by side in the horizontal direction. Thus, in addition to absorbing the external light incident on the diffusion sheet 4 and increasing the contrast of the screen, the image light from the linear Fresnel lens sheet 3 is diffused and emitted toward a wide range in the horizontal direction. Can do.

  On the other hand, the adhesive layer 44 is disposed adjacent to the light control layer 41 and the light output side diffusion layer 45, and joins the light control layer 41 and the light output side diffusion layer 45. The light exit side diffusion layer 45 is provided for diffusing the image light L from the linear Fresnel lens sheet 3 to emit the image light L toward a wide range of observers. Further, the hard coat layer 47 is provided to protect the display surface of the diffusion sheet 4 on which an image by the image light L is displayed. As each component constituting the diffusion sheet 4, those which are known per se in the transmissive screen 2 can be used, and therefore, detailed description thereof is omitted here.

  Next, the operation of the present embodiment configured as described above will be described with reference to the drawings.

  As shown in FIG. 2, the video light L emitted from the projection surface 8 of each light source 7 is incident on the second surface 12 side of the lens layer 10 of the linear Fresnel lens sheet 3. Each image light L incident on the linear Fresnel lens sheet 3 has a smaller angle with the normal direction nd to the sheet surface 3a of the linear Fresnel lens sheet 3 on the lens surface 14 of the corresponding linear Fresnel lens unit 13. More specifically, it is deflected so as to be substantially parallel. Each image light L deflected by the lens surface 14 enters the diffusion sheet 4 while maintaining the traveling direction in a direction substantially parallel to the normal direction nd to the sheet surface 3a of the linear Fresnel lens sheet 3. Each video light L incident on the diffusion sheet 4 is effectively diffused in the diffusion sheet 4 in various directions. Thereby, the image light L can be emitted toward a wide range of observers.

  In particular, according to the present embodiment, the plurality of linear Fresnel lens portions 13 are integrally formed. According to such a form, the relative positions of the plurality of linear Fresnel lens portions 13 can be positioned with high accuracy. Further, by positioning the single linear Fresnel lens sheet 3 with respect to the light source 7, each linear Fresnel lens portion 13 included in the linear Fresnel lens sheet 3 can be easily and accurately positioned with respect to the corresponding light source 7. It becomes possible to do. As a result, an image formed by the video light L from the adjacent light sources 7 can be smoothly connected.

  Further, according to the present embodiment, the lengths u of the linear Fresnel lens portions 13 in the first direction d1 are the same. In this case, the size of the image formed by the video light L transmitted through each linear Fresnel lens portion 13 can be made the same size. That is, since a plurality of images having the same size can be displayed on the light outgoing side surface 2a of the transmissive screen 2, the design is excellent.

  Furthermore, according to the present embodiment, the plurality of linear Fresnel lens portions 13 are formed identical to each other. In this case, the light sources 7 used for the respective linear Fresnel lens portions 13 can have the same configuration. For this reason, the versatility of the light source 7 to be used increases, and the transmissive display apparatus 1 can be manufactured efficiently.

  Next, a method for manufacturing the linear Fresnel lens sheet 3 will be described mainly with reference to FIG. FIG. 4 is a schematic view showing an example of a method for producing the linear Fresnel lens sheet 3 shown in FIG.

  As shown in FIG. 4, a base sheet 131 made of the base material 30 of the linear Fresnel lens sheet 3 is unwound from a roll-shaped raw fabric 132, and a roll-shaped mold 134 for shaping the linear Fresnel lens portion 13. And the pressure roller 133. The roll-shaped die 134 is formed with a concave portion having a shape complementary to each lens surface 14 of the plurality of linear Fresnel lens portions 13. Next, the ultraviolet curable resin 142 supplied from the ultraviolet curable resin supply unit 135 is supplied between the roll-shaped mold 134 and the base sheet 131. Then, the base sheet 131 and the ultraviolet curable resin 142 are sandwiched between the pressure roller 133 and the roll-shaped mold 134 and conveyed along the outer periphery of the roll-shaped mold 134. An ultraviolet lamp 136 is disposed in the vicinity of the outer periphery of the roll-shaped mold 134, and ultraviolet rays are irradiated from the ultraviolet lamp 136, and the ultraviolet curable resin 142 being conveyed is cured, and each ultraviolet curable resin 142 is cured. The linear Fresnel lens part 13 is shaped. The cured ultraviolet curable resin 142 is fixed to the base sheet 131. Further, the base sheet 131 to which the ultraviolet curable resin 142 is fixed is peeled from the roll-shaped mold 134 by the peeling roller 137. From the ultraviolet curable resin 142 and the base sheet 131, the linear Fresnel lens sheet 3 including the lens layer 10 including the plurality of linear Fresnel lens portions 13 and the base 30 is obtained.

  According to such a manufacturing method, the plurality of linear Fresnel lens portions 13 can be molded integrally with the lens layer 10 with high accuracy. Moreover, since the linear Fresnel lens sheet 3 can be continuously and stably manufactured using the roll-shaped mold 134, it is inexpensive and has high manufacturing efficiency. That is, a so-called roll-to-roll, in other words, using a long material wound in a roll shape, a large number of linear Fresnel lens sheets 3 can be manufactured in a connected state. For this reason, many linear Fresnel lens sheets 3 can be manufactured efficiently at low cost.

  In the method of manufacturing the linear Fresnel lens sheet 3 shown in FIG. 4, the example in which the lens layer 10 made of the ultraviolet curable resin is formed using the roll-shaped mold 134 is shown, but the present invention is not limited to such an example. . For example, the lens layer 10 including the plurality of linear Fresnel lens portions 13 may be manufactured by injection molding using a thermoplastic resin. Or the lens layer 10 provided with the some linear Fresnel lens part 13 may be manufactured by extrusion molding using a thermoplastic resin. According to the extrusion molding, each linear Fresnel lens portion 13 can be formed on the lens layer 10 without stacking the base material 30 on the lens layer 10.

  In the embodiment described above, the transmissive display device 1 includes the plurality of light sources 7 having the projection surfaces 8 that project the video light L onto the linear Fresnel lens sheet 3, and the projection surfaces 8 of the light sources 7 correspond to each other. Although an example in which the image light L is projected onto the linear Fresnel lens unit 13 is shown, the number of the light sources 7 is not limited to such an example. The transmissive display device may include a single light source having a plurality of projection surfaces for projecting image light onto the linear Fresnel lens sheet 3. In this case, each projection surface of a single light source projects image light onto the corresponding linear Fresnel lens unit 13. Then, in order to suppress the incident angle of the image light on the lens surface 14, each image light from the light source may be incident on the corresponding linear Fresnel lens unit 13 via a deflecting unit such as a mirror.

DESCRIPTION OF SYMBOLS 1 Transmission type display apparatus 2 Transmission type screen 2a Light emission side surface 3 Linear Fresnel lens sheet 3a Sheet surface 4 Diffusion sheet 7 Light source 8 Projection surface 10 Lens layer 11 First surface 12 Second surface 13 Linear Fresnel lens surface 13a First lens Surface group 13b second lens surface group 14 lens surface 14a first lens surface 14b second lens surface 15 rise surface 15a first rise surface 15b second rise surface 30 base material α lens angle d1 first direction L image light O optical center

Claims (8)

It has a plurality of linear Fresnel lens parts molded in one piece,
Each linear Fresnel lens part is a linear Fresnel lens sheet having an optical center. Each linear Fresnel lens part has a plurality of lens surfaces arranged along the first direction,
The linear Fresnel lens sheet according to claim 1, wherein the plurality of linear Fresnel lens portions are arranged side by side along the first direction. It has a plurality of linear Fresnel lens parts molded in one piece,
Each linear Fresnel lens unit includes a first lens surface group, and a second lens surface group disposed on one side of the first lens surface group,
The first lens surface group includes a plurality of first lens surfaces that are inclined to the same side with respect to the normal direction to the sheet surface of the linear Fresnel lens sheet,
The second lens surface group includes a plurality of second lens surfaces inclined to a side opposite to the first lens surface with respect to a normal direction to the sheet surface of the linear Fresnel lens sheet. . The plurality of first lens surfaces and the plurality of second lens surfaces are each arranged along a first direction,
The linear Fresnel lens sheet according to claim 3, wherein the plurality of linear Fresnel lens portions are arranged side by side along the first direction.   The linear Fresnel lens sheet according to claim 1, wherein the plurality of linear Fresnel lens portions are formed identical to each other.   A transmissive display device comprising the linear Fresnel lens sheet according to any one of claims 1 to 5. A light source having a plurality of projection surfaces for projecting image light onto the linear Fresnel lens sheet;
The transmissive display apparatus according to claim 6, wherein each projection surface projects image light onto a corresponding linear Fresnel lens unit. A plurality of light sources having a projection surface for projecting image light onto the linear Fresnel lens sheet;
The transmissive display device according to claim 6, wherein the projection surface of each light source projects image light onto a corresponding linear Fresnel lens unit.

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