Light guide film and manufacturing method thereof

Abstract

This light guide film (X) is provided with a transparent resin film (10), a plurality of half mirror (HM) films (21), and a plurality of HM films (22). The transparent resin film (10) has a first surface (10A) and a second surface (10B) opposite to the first surface (10A), and includes an array region (R1) and an array region (R2). The first surface (10A) includes a plurality of upright surfaces (11) in the array region (R1). The upright surfaces (11) each extend in a first direction (D1) and are separated from each other in a second direction (D2). The first surface (10A) includes a plurality of inclined surfaces (13) in the array region (R2). The inclined surfaces (13) each extend in the third direction (D3) and are separated from each other in the fourth direction (D4). The angle between the first direction (D1) and the third direction (D3) is 30-60 degrees, and the angles of the upright surface (11) and the inclined surface (13) with respect to the surface direction (D) are 85-90 degrees and 20-70 degrees. An HM film (21) is provided on the upright surface (11), and an HM film (22) is provided on the inclined surface (13).

Description

Technical Field

[0001] This invention relates to light guide films and their manufacturing methods. Background Technology

[0002] AR (Augmented Reality) glasses are known. AR glasses are wearable devices that are glasses-like and worn on the user's head. AR glasses overlay real-world scenes with digital images onto the user. Therefore, users can visually confirm an expanded virtual world using AR glasses.

[0003] AR glasses comprise a light guide plate, a micro-projector, and a frame. The light guide plate is held within the frame in a position opposite to the user's eyes. The light guide plate may have a shape similar to eyeglass lenses. The micro-projector is held within the frame in a position that allows image light (light used to form an image) to enter the light guide plate from a portion of the light guide plate. For example, Patent Document 1 describes such a technology related to the light guide plate of AR glasses.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2019 / 087576 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] like FIG. 10 As shown, the light guide plate 100 of Patent Document 1 has inner reflective surfaces 110 and 120 and end faces 130 and 140. The inner reflective surfaces 110 and 120 are separated from each other and parallel in the thickness direction H. The inner reflective surface 110 is the surface facing the user's face. The end faces 130 and 140 are separated in a direction D' orthogonal to the thickness direction H. The direction D' is, for example, transverse. Furthermore, the light guide plate 100 has a plurality of partial reflective surfaces 150 inside. The partial reflective surfaces 150 are semi-transparent and semi-reflective mirrors. Each partial reflective surface 150 extends in a direction orthogonal to the thickness direction H and the direction D' (e.g., longitudinally) and is inclined relative to the inner reflective surfaces 110 and 120. The plurality of partial reflective surfaces 150 are arranged spaced apart from each other in the direction D' and are parallel to each other.

[0009] In the AR glasses having the light guide plate 100, image light L' from a micro projector (omitted from the drawing) is injected into the light guide plate 100 at the end face 130 via a light coupling portion (omitted from the drawing). In the light guide plate 100, the image light L' repeatedly undergoes total reflection at the internal reflection faces 110, 120 from the end face 130, and then advances toward the end face 140 side. The partial reflection face 150 makes a part of the image light L' advancing in the light guide plate 100 pass through, and makes another part of the image light L' reflect. The image light L' reflected by the partial reflection face 150 is emitted out of the light guide plate 100 from the internal reflection face 110 (the user side in the light guide plate 100). The image light L' is duplicated in the light guide plate 100 in the above-described manner. Thereby, in the direction D', the eyebox (a range in which a user can visually confirm an image) of the AR glasses is enlarged.

[0010] According to Patent Literature 1, the light guide plate 100 is manufactured as follows.

[0011] First, as shown in FIG. 11 A , a required number of plates 101 (a case where the number of prepared plates is exemplarily illustrated as 5) are prepared. The plate 101 is formed of glass or resin. A face in a thickness direction side of the plate 101 other than the plate 101 in which the end face 130 FIG. 10 is formed (the plates 101a to 101d in FIG. 11 A ) is formed with the partial reflection face 150 in advance. The partial reflection face 150 is formed by film formation of a material having a prescribed refractive index difference with respect to the plate 101.

[0012] Next, as shown in FIG. 11 B , the plurality of plates 101 are joined. Specifically, the plurality of plates 101 are joined with the configuration in which the plates 101 and the partial reflection faces 150 are alternately connected by means of an adhesive (joining process). Thereby, the plate stack 100A is obtained.

[0013] Next, as shown in FIG. 11 C , the plate stack 100A is subjected to cutting processing (cutting processing process).

[0014] According to Patent Literature 1, the light guide plate 100 is manufactured in the above-described manner. However, in such a light guide plate manufacturing method, the above-described joining process and cutting processing process need to be implemented, and it is not efficient. Further, the light guide plate 100 of Patent Literature 1 enlarges the eyebox in one direction. That is, the light guide plate 100 has a configuration for one-dimensional pupil replication. The light guide plate 100 does not have a configuration for two-dimensional pupil replication (a configuration that enlarges the eyebox in two directions).

[0015] The present application provides a light guide film and a manufacturing method thereof, which are suitable for two-dimensional pupil replication and are suitable for efficient manufacturing.

[0016] Solution for solving the problem

[0017] The present application [1] includes a light guide film, wherein the light guide film comprises: a transparent resin film having a first surface and a second surface on the side opposite to the first surface; a plurality of first transflective mirror films; and a plurality of second transflective mirror films, the transparent resin film includes a first array region and a second array region, in the first array region, the first surface includes a plurality of upright surfaces each extending in a first direction in the first surface, mutually separated in a second direction orthogonal to the first direction, and mutually parallel, an angle of the upright surface with respect to a surface direction orthogonal to a thickness direction of the transparent resin film is 85° or more and 90° or less, in the second array region, the first surface includes a plurality of inclined surfaces each extending in a third direction in the first surface, mutually separated in a fourth direction orthogonal to the third direction, and mutually parallel, an angle of the inclined surface with respect to the surface direction is 20° or more and 70° or less, an angle formed by the first direction and the third direction in the first surface is 30° or more and 60° or less, the first transflective mirror film is disposed on each of the plurality of upright surfaces, and the second transflective mirror film is disposed on each of the plurality of inclined surfaces.

[0018] The present application [2] includes the light guide film according to the above-mentioned [1], wherein the first transflective mirror film has a light reflectance of 3% or more and 20% or less at a wavelength of 380 nm to 780 nm.

[0019] The present application [3] includes the light guide film according to the above-mentioned [1] or [2], wherein a length of the first transflective mirror film in the thickness direction is 5 μm or more and 100 μm or less.

[0020] The present application [4] includes the light guide film according to any one of the above-mentioned [1] to [3], wherein an arrangement pitch of the plurality of first transflective mirror films in the second direction is 3 μm or more and 500 μm or less.

[0021] The present application [5] includes the light guide film according to any one of the above-mentioned [1] to [4], wherein the second transflective mirror film has a light reflectance of 3% or more and 20% or less at a wavelength of 380 nm to 780 nm.

[0022] The present application [6] includes the light guide film according to any one of the above-mentioned [1] to [5], wherein a length of the second transflective mirror film in the thickness direction is 5 μm or more and 100 μm or less.

[0023] The present application [7] includes the light guide film according to any one of the above [1] to [6], wherein the arrangement pitch of the plurality of second transflective films in the fourth direction is 3 μm or more and 500 μm or less.

[0024] The present application [8] includes the light guide film according to any one of the above [1] to [7], wherein the ratio of the light transmittance of the light guide film at a wavelength of 380 nm to 780 nm to the light transmittance of the transparent resin film at a wavelength of 380 nm to 780 nm is 80% or more and 99% or less.

[0025] The present application [9] includes the light guide film according to any one of the above [1] to [8], wherein the light guide film further includes a resin layer, the resin layer being disposed on the first surface and covering the first transflective film and the second transflective film.

[0026] The present application

[10] includes the light guide film according to the above [9], wherein the distance in the thickness direction between the surface on the opposite side of the transparent resin film of the resin layer and the first transflective film is 1 μm or more and 100 μm or less.

[0027] The present application

[11] includes the light guide film according to the above [9] or

[10] , wherein the distance in the thickness direction between the surface on the opposite side of the transparent resin film of the resin layer and the second transflective film is 1 μm or more and 100 μm or less.

[0028] The present application

[12] includes the light guide film according to any one of the above [9] to

[11] , wherein the light guide film further includes a first low-refractive layer and a second low-refractive layer, the first low-refractive layer being disposed on the surface on the opposite side of the transparent resin film of the resin layer, having a lower refractive index than the resin layer, the second low-refractive layer being disposed on the second surface, having a lower refractive index than the transparent resin film.

[0029] The present application

[13] includes a method for manufacturing a light guide film, which is a method for manufacturing the light guide film described in any one of the above-mentioned [1] to

[12] , the method for manufacturing a light guide film including: a preparation step of preparing a transparent resin film having a first surface and a second surface on the side opposite to the first surface; a shape transfer step of pressing a shape mold against the first surface of the transparent resin film after the preparation step; a film formation step of forming a semi-transmissive and semi-reflective mirror layer on the first surface of the transparent resin film after the shape transfer step; and a patterning step of patterning the semi-transmissive and semi-reflective mirror layer, the shape mold having a first mold surface corresponding to the surface relief shape of the first array region and a second mold surface corresponding to the surface relief shape of the second array region, in the shape transfer step, the first array region and the second array region are formed on the first surface by pressing the first mold surface and the second mold surface against the first surface, and in the patterning step, the first semi-transmissive and semi-reflective mirror film on the upright surface and the second semi-transmissive and semi-reflective mirror film on the inclined surface are formed from the semi-transmissive and semi-reflective mirror layer.

[0030] The present application

[14] includes the method for manufacturing a light guide film described in the above-mentioned

[13] , wherein the method for manufacturing a light guide film further includes: a resin layer formation step of forming a resin layer covering the first semi-transmissive and semi-reflective mirror film and the second semi-transmissive and semi-reflective mirror film on the first surface.

[0031] The present application

[15] includes the method for manufacturing a light guide film described in the above-mentioned

[14] , wherein the method for manufacturing a light guide film further includes: a first low-refractive layer formation step of forming a first low-refractive layer having a lower refractive index than the resin layer on the resin layer.

[0032] The present application

[16] includes the method for manufacturing a light guide film described in any one of the above-mentioned

[13] to

[15] , wherein the method for manufacturing a light guide film further includes: a second low-refractive layer formation step of forming a second low-refractive layer having a lower refractive index than the transparent resin film on the second surface.

[0033] Effects of the Invention

[0034] In the light guide film of the present application, as described above, the transparent resin film includes the first array region and the second array region. In the first array region, the first face includes a plurality of upright faces each extending in a first direction, mutually separated in a second direction orthogonal to the first direction, and mutually parallel, and an angle of the upright face with respect to a face direction orthogonal to a thickness direction of the transparent resin film is 85° or more and 90° or less. A first half mirror (first HM) film is disposed on each of the plurality of upright faces. Such a first array region with the first HM film is suitable for copying image light in one direction (first copying direction) and reflecting the image light toward the second array region in a transmission process of the image light which is incident to the first array region of the transparent resin film and propagates in the region.

[0035] Further, in the second array region, the first face includes a plurality of inclined faces each extending in a third direction, mutually separated in a fourth direction orthogonal to the third direction, and mutually parallel, and an angle of the inclined face with respect to the face direction is 20° or more and 70° or less. A second half mirror (second HM) film is disposed on each of the plurality of inclined faces. Further, in the first face, an angle formed by the third direction (extending direction of the inclined face of the second array region) with respect to the first direction (extending direction of the upright face of the first array region) is 30° or more and 60° or less. Such a second array region with the second HM film is suitable for copying the image light (copied in the first copying direction) from the first array region in one direction (second copying direction crossing the first copying direction) and reflecting the image light toward the outside of the light guide film in a process in which the image light propagates in the second array region. Thus, the light guide film is suitable for two-dimensional pupil replication (two-dimensional replication in the first copying direction and the second copying direction) of the image light.

[0036] Further, the first array region and the second array region of the light guide film can be formed by pressing a shaped mold to the first face of the transparent resin film (shaped transfer process), the shaped mold having a first mold face corresponding to a surface relief shape of the first array region and a second mold face corresponding to a surface relief shape of the second array region. That is, in the manufacture of the light guide film, the above-mentioned joining process ( FIG. 11 B ) and the cutting process ( FIG. 11 C ) related to the prior art are not necessary. Thus, the light guide film is suitable for efficient manufacture.

[0037] As described above, the light guide film of the present application is suitable for two-dimensional pupil replication, and is suitable for efficient manufacture.

[0038] The manufacturing method of the light guide film of the present application includes the preparation step, the embossing transfer step, the film forming step, and the patterning step as described above. In the embossing transfer step, the first array region and the second array region are formed on the first face of the transparent resin film by pressing the first mold face and the second mold face of the embossing mold against the first face. Therefore, the manufacturing method does not require the above-mentioned bonding step ( FIG. 11 B ) and the cutting processing step ( FIG. 11 C ) related to the prior art. Such a manufacturing method is suitable for efficiently manufacturing the above-mentioned light guide film. BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1 is a plan view of one embodiment of the light guide film of the present application.

[0040] FIG. 2 is a partial cross-sectional view along the line II-II of FIG. 1 .

[0041] FIG. 3 is a partial cross-sectional view along the line III-III of FIG. 1 .

[0042] FIG. 4 is a partial enlarged view of FIG. 3 (the case where the angle β1 is 45° or more).

[0043] FIG. 5 is a partial enlarged view of FIG. 3 (the case where the angle β1 is less than 45°).

[0044] FIGS. 6A-6C indicates the manufacturing method of the light guide film shown in FIG. 1 . FIG. 6A indicates the transparent resin film preparation step, FIG. 6B indicates the embossing transfer step, FIG. 6C indicates the semi-transmissive and semi-reflective mirror layer forming step (film forming step).

[0045] FIGS. 7A-7D indicates the subsequent step of the step shown in FIG. 6C . FIG. 7A indicates the patterning step, FIG. 7B indicates the resin layer forming step, FIG. 7C indicates the first low refractive index layer forming step, FIG. 7D indicates the second low refractive index layer forming step.

[0046] FIG. 8 is a partial cross-sectional view of one modification of the light guide film shown in FIG. 1 . In this modification, the light guide film does not have the first low refractive index layer.

[0047] FIG. 9 isFIG. 1 Partial cross-sectional view of another modification example of the light guide film shown. In this modification example, the light guide film does not have a second low refractive index layer.

[0048] FIG. 10 Cross-sectional view of a light guide plate for use in existing AR glasses.

[0049] FIG. 11 shows FIG. 10 Manufacturing method of the light guide plate shown. DETAILED DESCRIPTION

[0050] As FIGS. 1-3 shown, the light guide film F, which is one embodiment of the present application, has a transparent resin film 10, a plurality of half mirror films 21 (first half mirror films) and a plurality of half mirror films 22 (second half mirror films), and in this embodiment, further has a resin layer 10', a low refractive index layer 31 (first low refractive index layer) and a low refractive index layer 32 (second low refractive index layer) (in FIG. 1 , the resin layer 10' and the low refractive index layers 31 and 32 are omitted). Specifically, the light guide film F has, in order in the thickness direction H: the low refractive index layer 32; the transparent resin film 10; the half mirror (HM) films 21 and 22; the resin layer 10'; and the low refractive index layer 31. The light guide film F extends in a direction (planar direction D) orthogonal to the thickness direction H. The light guide film F has a prescribed planar shape (exemplarily, a case where the planar shape of the light guide film F is rectangular is illustrated). The light guide film F is a light guide plate for use in AR glasses. The AR glasses, for example, have: the light guide plate (light guide film F), a light coupling portion, a micro projector, and a frame holding them.

[0051] The transparent resin film 10 is a substrate of the light guide film F. The transparent resin film 10 has a first surface 10A and a second surface 10B on the side opposite to the first surface 10A. The first surface 10A and the second surface 10B are separated from each other in the thickness direction H. The transparent resin film 10 includes an array region Rl (first array region) and an array region R2 (second array region) (exemplarily, a case where the planar shape of the array regions Rl and R2 is rectangular is illustrated). In this embodiment, the array regions Rl and R2 are adjacent in the long dimension direction of the light guide film F.

[0052] As FIG. 2 shown, the first surface 10A in the array region Rl includes a plurality of upright surfaces 11 and a plurality of surfaces 12. In FIG. 2 viewed in cross section, the upright surfaces 11 and the surfaces 12 are alternately arranged and continuous, forming a plurality of prismatic shapes (or sawtooth shapes) connected in the planar direction D.

[0053] As FIG. 1As shown, multiple vertical surfaces 11 extend in the first surface 10A along a first direction D1 and are separated from each other along a second direction D2 orthogonal to the first direction D1. The multiple vertical surfaces 11 are parallel to each other. FIG. 2 As shown, the angle α1 of the upright surface 11 relative to the surface direction D corresponds to the tilt angle of the HM film 21 described later. From the viewpoint of suppressing image blurring of the image light L (the light used to form the image) as confirmed by the user's vision, the angle α1 of the upright surface 11 is 85° or more and 90° or less, preferably 88° or more and 90° or less, and more preferably 90°.

[0054] like FIG. 1 As shown, multiple surfaces 12 extend in the first surface 10A along a first direction D1 and are separated from each other along a second direction D2 orthogonal to the first direction D1. Surfaces 12 can be flat or curved. From the viewpoint of suitably forming the HM film 21 on the upright surface 11, surfaces 12 are preferably flat. The angle α2 of the flat surface 12 relative to the surface direction D is set according to the angle α1 of the upright surface 11 described above, the arrangement spacing p1 of the HM film 21 described later, the width of the HM film 21, and other dimensions. The angle α2 is, for example, 20° or more and 40° or less.

[0055] like FIG. 3 As shown, the first surface 10A in array region R2 includes multiple inclined surfaces 13 and multiple surfaces 14. FIG. 3 As shown in the cross-sectional view, inclined surfaces 13 and 14 are arranged alternately and continuously, forming a series of continuous prism shapes (or serrated shapes) connected in the surface direction D.

[0056] like FIG. 1 As shown, multiple inclined surfaces 13 extend in the first surface 10A along a third direction D3 and are separated from each other along a fourth direction D4 orthogonal to the third direction D3. The multiple inclined surfaces 13 are parallel to each other. FIG. 3 As shown, the angle β1 of the inclined surface 13 relative to the surface direction D corresponds to the tilt angle of the HM film 22 described later. From the viewpoint of properly emitting the image light L after two-dimensional replication to the outside of the light guide film F, the angle β1 of the inclined surface 13 is 20° or more and 70° or less.

[0057] like FIG. 1As shown, the plurality of faces 14 each extend in the third direction D3 in the first face 10A, and are separated from each other in a fourth direction D4 orthogonal to the third direction D3. The faces 14 can be flat faces, or curved faces. From the viewpoint of appropriately forming the HM film 22 on the inclined face 13, the faces 14 are preferably flat faces. The angle β2 of the flat faces 14 with respect to the face direction D is set in accordance with the above-described angle β1 of the inclined face 13, the below-described arrangement pitch p2 of the HM film 22, the width and the like of the HM film 22. The angle β2 is, for example, 80° or more and 90° or less.

[0058] From the viewpoint of appropriately propagating the image light L from the array region R1 toward the array region R2, the angle γ formed by the first direction D1 (the direction of extension of the upright face 11) and the third direction D3 (the direction of extension of the inclined face 13) in the first face 10A is 30° or more, preferably 40° or more, more preferably 43° or more, and furthermore 60° or less, preferably 50° or less, more preferably 47° or less.

[0059] As the material of the transparent resin film 10, for example, a thermoplastic resin and a thermosetting resin can be cited. From the viewpoint of appropriately forming the surface relief shape of the array regions R1, R2 in the below-described excipient transfer process, the material of the transparent resin film 10 is preferably a thermoplastic resin.

[0060] From the viewpoint of achieving appropriate light guidance within the light guide film F, the refractive index of the transparent resin film 10 is, for example, 1.2 or more, preferably 1.5 or more, and furthermore, for example, 2.8 or less, preferably 2.5 or less.

[0061] The thickness (the maximum value in the thickness direction H) of the transparent resin film 10 is, for example, 0.1 mm or more, preferably 1.0 mm or more, and furthermore, for example, 5.0 mm or less, preferably 2.0 mm or less.

[0062] The HM film 21 is disposed on each of the plurality of upright faces 11. Each HM film 21 is preferably disposed on the entire face of one upright face 11. The HM film 21 transmits a part of the image light L advancing within the light guide film F, and reflects another part of the image light L. That is, the HM film 21 has both reflectivity and transmissivity with respect to the image light L. The HM film 21 is formed of a high-refractive material having a refractive index larger than that of the transparent resin film 10, or a low-refractive material having a refractive index smaller than that of the transparent resin film 10. As the high-refractive material, for example, titanium oxide and niobium oxide can be cited. As the low-refractive material, for example, nanoporous silica can be cited. The material of the HM film 21 is preferably nanoporous silica. The above content regarding the material of the HM film 21 is the same for the material of the below-described HM film 22.

[0063] The difference in refractive index between the HM film 21 and the transparent resin film 10 and the resin layer 10', for example, is 0.1 to 2 from the viewpoint of balancing the transmission and reflection of the image light L in the HM film 21.

[0064] The thickness of the HM film 21 is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 10 μm or less, and more preferably 8 μm or less from the viewpoint of balancing the transmission and reflection of the image light L in the HM film 21.

[0065] The light reflectance of the HM film 21 at a wavelength of 380 nm to 780 nm is preferably 3% or more, more preferably 7% or more, and further preferably 10% or more from the viewpoint of securing the amount (light quantity) of the reflection of the image light L from the HM film 21 toward the array region R2. The light reflectance of the HM film 21 at a wavelength of 380 nm to 780 nm is preferably 20% or less, more preferably 17% or less, and further preferably 15% or less from the viewpoint of suppressing the attenuation of the image light L when passing through the HM film 21.

[0066] The length h1 of the HM film 21 in the thickness direction H is preferably 5 μm or more, and more preferably 10 μm or more from the viewpoint of suppressing image blurring due to light scattering. The length h1 is preferably 100 μm or less, and more preferably 80 μm or less from the viewpoint of suppressing the attenuation of the image light L when passing through the HM film 21.

[0067] The arrangement pitch pl of the plurality of HM films 21 in the second direction D2 is preferably 3 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more from the viewpoint of suppressing image blurring due to light scattering. The arrangement pitch pl is the distance between the end portions of the low-refractive-layer 31 side (upper end side in the drawing) of adjacent HM films 21, 21. The arrangement pitch pl is preferably 500 μm or less, more preferably 300 μm or less, and further preferably 100 μm or less from the viewpoint of securing the visual confirmability of the real scene.

[0068] The HM film 22 is disposed on each of the plurality of inclined surfaces 13. Each HM film 22 is preferably disposed on the entire surface of one inclined surface 13. The HM film 22 transmits a part of the image light L advancing in the light guide film F and reflects another part of the image light L. That is, the HM film 22 has both reflectivity and transmissivity with respect to the image light L.

[0069] The difference in refractive index between the HM film 22 and the transparent resin film 10 and the resin layer 10', for example, is 0.1 to 2 from the viewpoint of balancing the transmission and reflection of the image light L in the HM film 22.

[0070] From the viewpoint of the balance between the transmission and the reflection of the image light L in the HM film 22, the thickness of the HM film 22 is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 10 μm or less, more preferably 8 μm or less.

[0071] From the viewpoint of securing the amount (light quantity) of the reflection of the image light L from the HM film 22 to the outside of the light guide film F, the light reflectance of the HM film 22 at a wavelength of 380 nm to 780 nm is preferably 3% or more, more preferably 7% or more, and further preferably 10% or more. From the viewpoint of suppressing the attenuation of the image light L when passing through the HM film 22, the light reflectance of the HM film 22 at a wavelength of 380 nm to 780 nm is preferably 20% or less, more preferably 17% or less, and further preferably 15% or less.

[0072] From the viewpoint of suppressing image blurring due to light scattering, the length h2 of the HM film 22 in the thickness direction H is preferably 5 μm or more, more preferably 10 μm or more. In order to suppress the angle β1 of the inclined surface 13 to 70° or less, the length h2 is preferably 100 μm or less, more preferably 80 μm or less.

[0073] From the viewpoint of suppressing image blurring due to light scattering, the arrangement pitch p2 of the plurality of HM films 22 in the second direction D2 is preferably 3 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. The arrangement pitch p2 is the distance between the end portions of the low-refractive-index layers 31 (upper end side in the drawing) of the adjacent HM films 22, 22. From the viewpoint of securing the visual confirmability of the real scene, the arrangement pitch p2 is preferably 500 μm or less, more preferably 300 μm or less, and further preferably 100 μm or less.

[0074] The resin layer 10' is disposed on the first surface 10A and covers the HM film 21 and the HM film 22. The transparent resin film 10 and the resin layer 10' form a light guide medium portion in the light guide film F. The resin layer 10' has a surface 10C on the side opposite to the transparent resin film 10. The surface 10C is a flat surface in the present embodiment. The surface 10C is a surface on the side toward the user's eye. In the present embodiment, the second surface 10B of the transparent resin film 10 is parallel to the surface 10C of the resin layer 10'. The second surface 10B and the surface 10C are mutually opposing internal reflection surfaces.

[0075] As the material of the resin layer 10', for example, a thermoplastic resin and a thermosetting resin can be listed. It is preferable that the material of the resin layer 10' be the same as that of the transparent resin film 10. The refractive index of the resin layer 10' is, for example, 1.2 or more, preferably 1.5 or more, and further, for example, 2.8 or less, preferably 2.5 or less, from the viewpoint of achieving appropriate light guiding in the light guide film F. It is preferable that the refractive index of the resin layer 10' be the same as that of the transparent resin film 10.

[0076] The distance dl in the thickness direction H between the surface 10C of the resin layer 10' and the HM film 21 is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of protecting the HM film 21. Further, the distance d2 is preferably 100 μm or less, more preferably 70 μm or less, from the viewpoint of thinning the light guide film F.

[0077] The low-refractive-index layer 31 is disposed on the surface 10C of the resin layer 10'. The low-refractive-index layer 31 is in contact with the surface 10C. The low-refractive-index layer 31 preferably covers the entire surface of the surface 10C. In the present embodiment, the refractive index of the low-refractive-index layer 31 is smaller than that of the resin layer 10'. The refractive index of the low-refractive-index layer 31 is, in the range of being smaller than that of the resin layer 10', preferably 1.3 or less, more preferably 1.2 or less, from the viewpoint of appropriately achieving total reflection of the image light L at the surface 10C. The difference between the refractive index of the resin layer 10' and that of the low-refractive-index layer 31 is, in the range of being smaller than that of the resin layer 10', for example, 0.1 to 2, from the viewpoint of appropriately achieving total reflection of the image light L at the surface 10C.

[0078] As the material of the low-refractive-index layer 31, for example, nano-porous silica and the like can be listed, and it is preferable to use nano-porous silica (the same as the material of the low-refractive-index layer 32 to be described later).

[0079] The thickness of the low-refractive-index layer 31 is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of appropriately achieving total reflection of the image light L at the surface 10C. The thickness of the low-refractive-index layer 31 is, for example, 100 μm or less, from the viewpoint of securing the see-through property (transmission property of light rays from a real scene) of the light guide film F.

[0080] A low-refractive-index layer 32 is disposed on the second surface 10B of the transparent resin film 10. The low-refractive-index layer 32 is in contact with the second surface 10B. The low-refractive-index layer 32 preferably covers the entire surface of the second surface 10B. In this embodiment, the refractive index of the low-refractive-index layer 32 is smaller than the refractive index of the transparent resin film 10. From the viewpoint of appropriately achieving total internal reflection of the image light L on the second surface 10B, the refractive index of the low-refractive-index layer 32 is preferably 1.3 or less, more preferably 1.2 or less, in a range smaller than the refractive index of the transparent resin film 10. From the viewpoint of appropriately achieving total internal reflection of the image light L on the second surface 10B, the difference between the refractive index of the transparent resin film 10 and the refractive index of the low-refractive-index layer 32 is in a range smaller than the refractive index of the transparent resin film 10, for example, 0.1 to 2.

[0081] From the viewpoint of properly achieving total internal reflection of the image light L on the second surface 10B, the thickness of the low refractive index layer 32 is preferably 1 μm or more, more preferably 2 μm or more. From the viewpoint of ensuring the transparency of the light guide film F (the transmittance of light derived from the real scene), the thickness of the low refractive index layer 32 is, for example, 100 μm or less.

[0082] The ratio of the light transmittance of the light guide film F in the wavelength range of 380 nm to 780 nm to the light transmittance of the transparent resin film 10 in the same wavelength range is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, for example 100% or less, and most preferably 99% or less. This configuration is preferred for ensuring high transparency in the light guide film F.

[0083] FIGS. 6A-7D This describes a method for manufacturing the light guide film F. In this embodiment, the manufacturing method sequentially includes: a preparation step (…). FIG. 6A ), shaping and transfer process ( FIG. 6B ), film forming process ( FIG. 6C Patterning process ( FIG. 7A ), resin layer formation process (7B), first low refractive index layer formation process ( FIG. 7C ) and the second low-refractive-index layer formation process ( FIG. 7D ).

[0084] In the preparation process, such as FIG. 6A As shown, a transparent resin film 10R is prepared. The transparent resin film 10R is the raw material film for the transparent resin film 10. The materials of the transparent resin film 10R include those described above related to the transparent resin film 10. The transparent resin film 10R has a first surface 10A and a second surface 10B opposite to the first surface 10A.

[0085] In the shaping and transfer process, such as FIG. 6BAs shown, the conforming mold 200 is pressed against the first face 10A of the transparent resin film 10R. The conforming mold 200 has a first mold face 210 and a second mold face 220. The first mold face 210 has a surface relief shape corresponding to the surface relief shape of the array region Rl in the transparent resin film 10. The second mold face 220 has a surface relief shape corresponding to the surface relief shape of the array region R2 in the transparent resin film 10. In the conforming transfer process, the array region Rl and the array region R2 are formed on the first face 10A by pressing the first mold face 210 and the second mold face 220 against the first face 10A of the transparent resin film 10. Thus, the transparent resin film 10 is obtained.

[0086] In this process, the transparent resin film 10R is preferably heated. The heating temperature is a temperature at which the transparent resin film 10R is sufficiently softened and at which excessive thermal expansion and / or thermal deformation of the transparent resin film 10R is suppressed.

[0087] In the film formation process, as shown in FIG. 6C a material is caused to be deposited on the first face 10A of the transparent resin film 10, and a transflective mirror layer 20 is formed. The material of the transflective mirror layer 20 can be exemplified by the above-described materials related to the HM films 21, 22. The transflective mirror layer 20 has the above-described thickness related to the HM films 21, 22. As a method of forming the transflective mirror layer 20, a vacuum evaporation method and a sputtering method can be exemplified.

[0088] In the patterning process, as shown in FIG. 7A a plurality of HM films 21 and a plurality of HM films 22 are formed from the transflective mirror layer 20 FIG. 7B . Specifically, the HM films 21 are formed on the respective upright faces 11 and the HM films 22 are formed on the respective inclined faces 13 by patterning the transflective mirror layer 20. In this process, the transflective mirror layer 20 is etched, for example, with a prescribed etching mask. Thus, the transflective mirror layer 20 can be patterned. As an etching method, for example, a plasma etching can be exemplified. By this process, a transparent resin film 10 with HM films 21, 22 is obtained. The transparent resin film 10 with HM films 21, 22 is a light guide film that is an intermediate product in the process of manufacturing the light guide film F.

[0089] In the resin layer formation process, as shown in FIG. 7B a resin layer 10' is formed on the first face 10A of the transparent resin film 10. The resin layer 10' is formed so as to cover the HM films 21 and the HM films 22. The resin layer 10' can be formed, for example, by a prescribed coating method.

[0090] In the first low refractive index layer formation process, as shown in FIG. 7CAs shown, a low refractive index layer 31 is formed on the resin layer 10'. The low refractive index layer 31 can be formed, for example, by spraying. Specifically, a coating film can be formed on the surface 10C of the resin layer 10' by spraying a liquid low refractive index layer forming material, and then the coating film can be dried to form the low refractive index layer 31.

[0091] In the process of forming the second low-refractive-index layer, such as FIG. 7D As shown, a low refractive index layer 32 is formed on the second surface 10B of the transparent resin film 10. The low refractive index layer 32 can be formed, for example, by spraying. Specifically, a coating can be formed on the second surface 10B of the transparent resin film 10 by spraying a liquid low refractive index layer forming material, and then the coating can be dried to form the low refractive index layer 32.

[0092] The light guide film F can be manufactured in the manner described above.

[0093] In this manufacturing method, the above-mentioned film formation process can also be replaced by performing the resist pattern formation process, another film formation process, and the resist pattern removal process in sequence. FIG. 6C ) and patterning process ( FIG. 7A In the resist patterning process, a resist pattern with openings corresponding to the pattern shapes of the HM films 21 and 22 is formed on the first surface 10A of the transparent resin film 10. In the film-forming process, a film is formed on the first surface 10A of the transparent resin film 10 through the resist pattern, thereby forming the HM film 21 on the vertical surface 11 and the HM film 22 on the inclined surface 13. Then, the resist pattern is removed (resist pattern removal process). Furthermore, regarding the first low-refractive-index layer forming process in this manufacturing method... FIG. 7C ) and the second low refractive index layer formation process ( FIG. 7D Alternatively, it can be implemented in the order of forming the second low-refractive-index layer and forming the first low-refractive-index layer.

[0094] In AR glasses equipped with a light guide film F, image light L from a micro-projector (illustration omitted) is transmitted via an optical coupler LC (…). FIG. 1 (Schematably represented by imaginary lines) The light is incident on the array region R1 of the light guide film F. The optical coupling part LC is disposed, for example, in the low refractive index layer 31 of the light guide film F. FIG. 2 The optical coupling unit LC is, for example, a prism of a predetermined shape. Through the optical coupling unit LC, the image light L is... FIG. 1 The light is emitted into the light guide film F in the x-direction as shown in the top-down view.

[0095] like FIG. 2 As shown, the image light L incident into the light guide film F undergoes repeated total internal reflection on the second surface 10B and surface 10C, propagating in the x-direction within the array region R1.FIG. 1 As shown, each HM film 21 allows a portion of the image light L advancing within the light guide film F to pass through, and reflects another portion of the image light L toward the array region R2. The image light L is replicated in the form of the reflected light by the reflection of the HM film 21. That is, the image light L is replicated multiple times by multiple HM films 21. The image light L is replicated in the x-direction by multiple HM films 21 in the array region R1.

[0096] like FIG. 3 As shown, in the array region R2, the image light L repeatedly undergoes total internal reflection on the second surface 10B and surface 10C, propagating in the y-direction. Each HM film 22 allows a portion of the image light L advancing within the light guide film F to pass through, and causes another portion of the image light L to be reflected toward the surface 10C side. FIG. 4 This is an example of a case where the tilt angle β1 of the HM film 22 is 45° or more. FIG. 5 This is an example where the tilt angle β1 of the HM film 22 is less than 45°. The image light L is replicated in the form of the reflected light by the reflection of the HM film 22. That is, the image light L is replicated multiple times by multiple HM films 22. The image light L is replicated in the y-direction by multiple HM films 22 in the array region R2. The image light L, after being reflected by the HM film 22, passes through the surface 10C and the low refractive index layer 31 and exits outside the light guide film F (the incident angle relative to the surface 10C and the low refractive index layer 31 is small, so the image light L does not undergo total internal reflection at the surface 10C).

[0097] The image light L emitted to the light guide film F is replicated in two directions (two-dimensional pupil replication) in the manner described above. As a result, in the planar direction D, the eye box of the AR glasses (the range in which the user can visually confirm the image) is expanded in both directions.

[0098] As described above, the transparent resin film 10 of the light guide film F includes an array region R1 and an array region R2. In the array region R1, as described above, the first surface 10A includes a plurality of upright surfaces 11, each extending in a first direction D1, separated from each other in a second direction D2 orthogonal to the first direction D1, and parallel to each other. The angle α1 of the upright surface 11 relative to the surface direction D is 85° or more and 90° or less. Furthermore, an HM film 21 is disposed on each of the plurality of upright surfaces 11. Such an array region R1 with an HM film 21 is suitable for replicating the image light L in one direction (a first replication direction) and reflecting the image light L toward the array region R2 during the transmission of image light L incident into and propagating within the array region R1 of the transparent resin film 10.

[0099] Further, in the array region R2, as described above, the first face 10A includes a plurality of inclined faces 13 each extending in a third direction D3, mutually separated in a fourth direction D4 orthogonal to the third direction D3, and mutually parallel in the first face 10A. An angle β1 of the inclined faces 13 with respect to the face direction D is 20° or more and 70° or less. The HM film 22 is disposed on each of the plurality of inclined faces 13. Further, in the first face 10A, an angle γ of the third direction D3 (an extension direction of the inclined faces 13 in the array region R2) with respect to the first direction D1 (an extension direction of the upright faces 11 in the array region R1) is 30° or more and 60° or less. Such an array region R2 with the HM film 22 is suitable for replicating the image light L in one direction (a second replication direction crossing the first replication direction) and reflecting the image light L toward the light guide film F outward during propagation of the image light L (replicated in the first replication direction) from the array region R1 within the array region R2. Therefore, the light guide film F is suitable for two-dimensional pupil replication (two-dimensional replication in the first replication direction and the second replication direction) of the image light L.

[0100] Further, as described above, the array region R1 and the array region R2 of the light guide film F can be formed by pressing the embossing mold 200 against the first face 10A of the transparent resin film 10 (embossing transfer process). That is, in the manufacture of the light guide film F, the above-mentioned bonding process ( FIG. 11 B ) and the cutting process ( FIG. 11 C ) related to the prior art are not necessary. Therefore, the light guide film F is suitable for efficient manufacture.

[0101] As described above, the light guide film F is suitable for two-dimensional pupil replication, and is suitable for efficient manufacture.

[0102] As for the light guide film F, it is also possible not to have the low-refractive layer 31 on the surface 10C of the resin layer 10' as shown in FIG. 8 From the viewpoint of suppressing reduction in total reflectivity of the image light at the surface 10C caused by attachment of foreign matter (for example, a water droplet) to the surface 10C, the light guide film F preferably has the low-refractive layer 31.

[0103] As for the light guide film F, it is also possible not to have the low-refractive layer 32 on the second face 10B of the transparent resin film 10 as shown in FIG. 9 FIG. 9 ​The light guide film F shown can also be complexed with another substrate. Specifically, the second face 10B side of the light guide film F can be attached to the surface of another substrate. The substrate is, for example, thicker than the light guide film F. As the material of the substrate, for example, resin, glass, and thin glass can be listed. In the case where the light guide film F is complexed with another substrate, a layer (low refractive index layer) having a refractive index smaller than the substrate is preferably formed on the surface of the substrate on the side opposite to the light guide film F. On the other hand, in the case where the light guide film F is not complexed with another substrate, the light guide film F preferably has a low refractive index layer 32 as shown FIG. 1

[0104] Note that the above-described application is provided as an example of an embodiment of the present application, but is simply an example and is not to be construed as a limitation. Variations of the present application that are clear to those skilled in the art are included in the technical solutions described.

[0105] Industrial applicability

[0106] The light guide film of the present application is, for example, used for AR glasses. The manufacturing method of the light guide film of the present application is used for the manufacture of light guide films.

[0107] Explanation of reference numerals

[0108] X: light guide film; H: thickness direction; D: surface direction; D1: first direction; D2: second direction; D3: third direction; D4: fourth direction; 10: transparent substrate film; R1: array region (first array region); R2: array region (second array region); 10A: first face; 10B: second face; 11: upright face; 13: inclined face; 10': resin layer; 10C: surface; 21: transflective mirror film (first transflective mirror film); 22: transflective mirror film (second transflective mirror film); 31: low refractive index layer (first low refractive index layer); 32: low refractive index layer (second low refractive index layer); 70: shaped mold; 71: first mold face; 72: second mold face.​

Claims

1. A light guide film, wherein, The light guide film has the following features: A transparent resin film having a first side and a second side opposite to the first side; Multiple first semi-transparent and semi-reflective mirror films; and Multiple second semi-transparent and semi-reflective mirror films, The transparent resin film includes a first array region and a second array region. In the first array region, the first surface includes a plurality of upright surfaces, each extending in a first direction, separated from each other in a second direction orthogonal to the first direction, and parallel to each other. The angle between the vertical surface and the plane orthogonal to the thickness direction of the transparent resin film is 85° or more and 90° or less. In the second array region, the first surface includes a plurality of inclined surfaces, each of which extends upward in a third direction, is separated from each other in a fourth direction orthogonal to the third direction, and is parallel to each other. The angle between the inclined surface and the direction of the surface is greater than 20° and less than 70°. In the first plane, the angle formed by the first direction and the third direction is greater than 30° and less than 60°. The first semi-transparent and semi-reflective film is disposed on each of the plurality of vertical surfaces. A second semi-transparent and semi-reflective film is disposed on each of the plurality of inclined surfaces.

2. The light guide film according to claim 1, wherein, The light reflectance of the first semi-transparent and semi-reflective mirror film in the wavelength range of 380nm to 780nm is more than 3% and less than 20%.

3. The light guide film according to claim 1, wherein, The length of the first semi-transparent and semi-reflective film in the thickness direction is more than 5 μm and less than 100 μm.

4. The light guide film according to claim 1, wherein, The spacing between the plurality of first semi-transparent and semi-reflective mirror films in the second direction is more than 3 μm and less than 500 μm.

5. The light guide film according to claim 1, wherein, The light reflectance of the second semi-transparent and semi-reflective mirror film in the wavelength range of 380nm to 780nm is more than 3% and less than 20%.

6. The light guide film according to claim 1, wherein, The length of the second semi-transparent and semi-reflective film in the thickness direction is more than 5 μm and less than 100 μm.

7. The light guide film according to claim 1, wherein, The spacing between the plurality of second semi-transparent and semi-reflective mirror films in the fourth direction is more than 3 μm and less than 500 μm.

8. The light guide film according to claim 1, wherein, The ratio of the light transmittance of the light guide film at wavelengths of 380nm to 780nm to the light transmittance of the transparent resin film at wavelengths of 380nm to 780nm is more than 80% and less than 99%.

9. The light guide film according to claim 1, wherein, The light guide film further comprises a resin layer, which is disposed on the first surface and covers the first semi-transparent and semi-reflective film and the second semi-transparent and semi-reflective film.

10. The light guide film according to claim 9, wherein, The distance in the thickness direction between the surface of the resin layer opposite to the transparent resin film and the first semi-transparent and semi-reflective film is more than 1 μm and less than 100 μm.

11. The light guide film according to claim 9, wherein, The distance in the thickness direction between the surface of the resin layer opposite to the transparent resin film and the second semi-transparent and semi-reflective film is more than 1 μm and less than 100 μm.

12. The light guide film according to claim 9, wherein, The light guide film further comprises a first low-refractive-index layer and a second low-refractive-index layer. The first low-refractive-index layer is disposed on the surface of the resin layer opposite to the transparent resin film, and has a lower refractive index than the resin layer. The second low-refractive-index layer is disposed on the second surface and has a lower refractive index than the transparent resin film.

13. A method for manufacturing a light guide film, comprising the method for manufacturing the light guide film as described in claim 1. The method for manufacturing the light guide film includes: The preparation process involves preparing a transparent resin film having a first side and a second side opposite to the first side. In the shaping and transfer process, the shaping mold is pressed onto the first side of the transparent resin film after the preparation process; In the film-forming process, a semi-transparent and semi-reflective layer is formed on the first surface of the transparent resin film after the shaping and transfer process; as well as The patterning process involves patterning the semi-transparent, semi-reflective layer. The forming mold has a first mold surface corresponding to the surface irregularity of the first array region and a second mold surface corresponding to the surface irregularity of the second array region. In the shaping and transfer process, by pressing the first mold surface and the second mold surface onto the first surface, the first array area and the second array area are formed on the first surface. In the patterning process, the first semi-transparent and semi-reflective film on the upright surface and the second semi-transparent and semi-reflective film on the inclined surface are formed from the semi-transparent and semi-reflective layer.

14. The method for manufacturing the light guide film according to claim 13, wherein, The manufacturing method of the light guide film further includes: a resin layer forming step, wherein a resin layer covering the first semi-transparent and semi-reflective film and the second semi-transparent and semi-reflective film is formed on the first surface.

15. The method for manufacturing the light guide film according to claim 14, wherein, The method for manufacturing the light guide film further includes: a first low refractive index layer forming step, wherein a first low refractive index layer having a lower refractive index than the resin layer is formed on the resin layer.

16. The method for manufacturing the light guide film according to claim 13, wherein, The method for manufacturing the light guide film further includes: a second low refractive index layer forming step, wherein a second low refractive index layer having a lower refractive index than the transparent resin film is formed on the second surface.

Images