JP2012198264A - Method for manufacturing light guide plate, light guide plate, and virtual image display including the light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a light guide plate for a virtual image display that enables display of excellent images, a light guide plate, and a virtual image display including the light guide plate.SOLUTION: In a method for manufacturing a light guide plate 20 according to the present embodiment, a pair of resin members, a first resin member B1 and a second resin member B2 are molded together, using resin member molding tools MP1 and MP2 each having both of a first molding section PP1 and a second molding section PP2 in a resin member molding process. Further, in an image drawing section forming process, the first and second resin members B1 and B2 are bonded together to form a single image drawing section 23. In this case, it is possible to suppress difference in refractive index between the first and second resin members B1 and B2 which form the image drawing section 23 as much as possible. Hence, angle displacement of image light due to unintended refraction in the image drawing section 23 is suppressed, whereby the light guide plate 20 that enables display of excellent images is manufactured.

Description

  The present invention relates to a method of manufacturing a light guide plate used for a head mounted display or the like used by being mounted on a head, a light guide plate, and a virtual image display device including the light guide plate.

  2. Description of the Related Art In recent years, various types of virtual image display devices that enable formation and observation of virtual images, such as a head-mounted display, have been proposed that guide video light from a display element to an observer's pupil using a light guide plate. As a light guide plate for such a virtual image display device, a large number of light beams are guided parallel to the main surface of the light guide plate on the exit side of the light guide plate while guiding image light using total reflection. There is known a technique in which image light is caused to reach an observer's retina by reflecting the image light on a partially reflecting surface and taking it out of the light guide plate (see Patent Document 1).

  In the configuration in which the image light is extracted by a number of partial reflection surfaces as described above, a part of the image light is reflected toward the pupil after passing through the partial reflection surface once or a plurality of times. In this case, if there is a difference in refractive index in the portion forming the partial reflection surface, the image light may be deteriorated by an angular shift in which the traveling direction changes due to unintentional refraction before and after passing through the partial reflection surface. is there.

JP 2004-157520 A

  The present invention has been made in view of the above problems of the background art, and provides a method for manufacturing a light guide plate for a virtual image display device capable of displaying a good image, a light guide plate, and a virtual image display device including the light guide plate. For the purpose.

  In order to solve the above problems, a method of manufacturing a light guide plate according to the present invention includes: (a) a light guide part; a light incident part that causes image light to enter the light guide part; and image light guided by the light guide part. A light emitting part having an image extraction part to be extracted to the outside, and a light guide plate manufacturing method comprising: (b) a first molding part for molding a first resin member constituting a part of the image extraction part; A mold preparing step of preparing a resin member molding die having both a second molding part that molds a second resin member that forms a pair with one resin member and constitutes another part of the image extraction unit; and (c) resin (D) a resin member molding step in which a resin material is filled in both the first molding portion and the second molding portion of the member molding die, and the first and second resin members are collectively molded from the resin member molding die; A first resin member and a second resin member molded together in the resin member molding step are bonded together as a pair. And an image extraction unit forming step of forming an image extraction section by the.

  In the light guide plate manufacturing method, in the resin member molding step, the pair of first and second resin members are molded together by a resin member molding die having both the first molded portion and the second molded portion, and the image In the extraction portion forming step, one image extraction portion is formed by bonding the first and second resin members. In this case, the difference in refractive index between the first resin member and the second resin member constituting the image extraction portion can be suppressed as much as possible. Therefore, a light guide plate capable of displaying a good image is manufactured by suppressing the angular deviation of the image light due to unintended refraction inside the image extraction portion.

  In a specific aspect of the present invention, in the image extraction portion forming step, a plurality of reflection units arranged in a predetermined arrangement direction constituting the image extraction portion are formed between the first resin member and the second resin member. For this purpose, a reflection film forming process is included in which a reflection film is formed on one of the molding surfaces of the first and second position resin members that are bonded to each other. In this case, image light can be individually reflected by the plurality of reflection units at the image extraction unit of the light emitting unit and extracted outside the light guide plate.

  In another aspect of the present invention, the plurality of reflection units have a plurality of partial reflection surfaces that allow at least a part of incident light to pass through the reflection film, and at least one of the image lights on any of the plurality of partial reflection surfaces. Pass the part one or more times. In this case, the image light passes through the plurality of partial reflection surfaces one or more times depending on the angle of incidence on the image extraction unit. Thus, each component of the image light can be emitted to the observer from an appropriate position.

  In yet another aspect of the present invention, (a) a pair of cross-sectional sawtooth surfaces in which the first resin member and the second resin member have mutually parallel inclined surfaces for constituting a plurality of reflection units and are mutually inverted. (B) in the image extraction portion forming step, the cross-sectional sawtooth surface of the first resin member is inverted by 180 ° with the longitudinal direction of the reflection unit as the axial direction, Paste to. Here, the cross-sectional sawtooth-shaped surface is formed, for example, by connecting a plurality of groove portions having the same shape in the first resin member, and by connecting a plurality of mountain portions having the same shape in the second resin member. In this case, the groove portion of the first resin member and the crest portion of the second resin member are bonded together without a gap, and a plurality of partial reflection surfaces are formed on the bonded portions.

  In still another aspect of the present invention, in the resin member molding step, the first and second resin members are molded by injection molding. In this case, the first and second resin members can be molded relatively easily and with high accuracy.

  In still another aspect of the present invention, in the resin member molding step, the first and second resin members are molded by ultraviolet curable resin molding. In this case, the first and second resin members having a fine shape can be molded relatively easily.

  In still another aspect of the present invention, the resin member molding die includes both the first molding part and the second molding part as a part of one continuous mold, and the first and second resin members are In addition, the resin members are molded in a continuous state in the resin member molding step, and are individually divided before the image extraction portion forming step. In this case, the first and second resin members with a small difference in refractive index can be molded relatively easily.

  In still another aspect of the present invention, in the resin member mold, the first molded portion and the second molded portion are adjacent to each other. In this case, the difference in refractive index between the molded first resin member and the second resin member can be made extremely small.

  In still another aspect of the present invention, the first resin member and the second resin member have the same shape. In this case, it is relatively easy to produce a resin member mold with high accuracy, and the accuracy of an image extraction portion or the like obtained by combining the obtained first and second resin members can be improved.

  In still another aspect of the present invention, the resin member molding die further includes a third molding portion that molds a third resin member that constitutes a main body portion of the light emitting portion that joins the image extraction portion. In this case, it is possible to increase the degree of freedom of the shape of the first and second resin members, and to form a highly accurate light emitting portion while suppressing a difference in refractive index between the main body portion of the light emitting portion and the image extraction portion.

  In order to solve the above problems, a light guide plate according to the present invention is manufactured by any one of the above-described methods for manufacturing a light guide plate. In this case, the manufactured light guide plate can emit image light in a good state.

  In order to solve the above problems, a virtual image display device according to the present invention includes (a) the light guide plate and (b) an image forming apparatus that forms image light guided to the light guide plate. In this case, the virtual image display device can display a good image by using the light guide plate.

(A) is sectional drawing which shows the virtual image display apparatus which concerns on 1st Embodiment, (B) and (C) are the front views and top views of the light-guide plate which concern on embodiment. (A) is sectional drawing explaining the structure of the back | inner side part of the image extraction part in a light-guide plate, (B) is sectional drawing explaining the structure of the part by the side of the entrance of an image extraction part. It is a figure which shows the mode of the light which passes an image extraction part. It is a figure of the flowchart for demonstrating the manufacturing method of the light-guide plate which concerns on 1st Embodiment. (A) is a top view which shows the manufactured light-guide plate, (B) is a figure for demonstrating shaping | molding of each part by injection molding, (C)-(E) shape | molds an image extraction part. It is a figure which shows the process to do. (A) is a top view which shows the light-guide plate manufactured by the manufacturing method of the light-guide plate which concerns on 2nd Embodiment, (B) is a figure which shows the type | mold used for injection molding, and the resin member shape | molded. is there. It is a figure of the flowchart for demonstrating the manufacturing method of the light-guide plate which concerns on 3rd Embodiment. (A) is a top view which shows the manufactured light-guide plate, (B) is a figure which shows the type | mold used for injection molding, and the resin molded product shape | molded. (A)-(C) are figures which show the process of shape | molding an image extraction part. (A) And (B) is a figure which shows the manufacturing process for demonstrating the manufacturing method of the light-guide plate which concerns on 4th Embodiment.

[First Embodiment]
Hereinafter, a light guide plate for a virtual image display device manufactured by the method for manufacturing a light guide plate according to the first embodiment of the present invention and a virtual image display device incorporating the same will be described with reference to the drawings.

[A. Structure of light guide plate and virtual image display device]
A virtual image display device 100 according to this embodiment shown in FIG. 1A is applied to a head-mounted display, and includes an image forming device 10 and a light guide plate 20 as a set. 1A corresponds to the AA cross section of the light guide plate 20 shown in FIG.

  The virtual image display device 100 allows an observer to recognize image light based on a virtual image, and allows the observer to observe an external image in a see-through manner. The image forming apparatus 10 and the light guide plate 20 are usually provided one by one corresponding to the right eye and the left eye of the observer. However, since the right eye and the left eye are symmetrical, the left eye is used here. For the right eye, illustration is omitted. The virtual image display device 100 as a whole has, for example, an appearance (not shown) like general glasses.

  As illustrated in FIG. 1A, the image forming apparatus 10 includes a liquid crystal device 11 and a projection optical system 12. Among these, the liquid crystal device 11 includes an illumination device 31 that emits two-dimensional illumination light, a liquid crystal display device 32 that is a transmissive spatial light modulation device, and an emission angle adjusting member 33 disposed therebetween. Have The liquid crystal display device 32 spatially modulates the illumination light from the illumination device 31 to form image light to be a display target such as a moving image. The projection optical system 12 is a collimating lens that converts image light emitted from each point on the liquid crystal display device 32 into light beams in a parallel state. The emission angle adjusting member 33 changes the emission angle distribution of the illumination light according to the position in the screen so that the image light emitted from the liquid crystal display device 32 is efficiently incident on the eye EY of the observer. It is adjusting.

  As shown in FIGS. 1B and 1C, the light guide plate 20 includes a light incident part D1, a light guide part D2, and a light emitting part D3. The light incident part D1 has a light incident surface IS and an incident light folding curved surface 21, and takes in the image light from the image forming apparatus 10 from the light incident surface IS and directs the taken image light toward the light guide part D2. Bend it. The light guide unit D2 includes a total reflection surface forming unit 22, and propagates the captured image light toward the light emitting unit D3. In addition, the direction which the light guide part D2 guides as the whole light beam shall be called a light guide direction. That is, here, the Z direction is the light guide direction. The light emission unit D3 includes an image extraction unit 23 that is an angle conversion unit and a light emission surface OS, converts the angle of the image light propagated by the light guide unit D2, and emits image light from the light emission surface OS. .

  The light incident part D1 has a light incident surface IS on a plane on the front side that is parallel to the YZ plane and faces the image forming apparatus 10. The light incident part D1 has a rectangular inclined surface RS in addition to the light incident surface IS as a side surface of the thick part of the quadrangular columnar shape, and a mirror layer 21a is formed on the inclined surface RS by film formation such as aluminum vapor deposition. Is formed. That is, the incident light folding curved surface 21 is formed by the cooperation of the mirror layer 21a and the inclined surface RS. The incident light folding surface 21 bends the image light that is incident from the light incident surface IS and travels in the + X direction as a whole so as to be directed in the + Z direction that is biased in the −X direction as a whole. Lead in.

  The light guide part D2 extends from the light incident part D1 side which is the entrance side to the light emission part D3 side which is the back side, and guides the image light incident inside to the image extraction part 23 of the light emission part D3. The total reflection surface forming part 22 is provided.

  The total reflection surface forming portion 22 is a flat main surface for functioning as the light guide portion D2, and is a first flat surface that totally reflects image light as two flat surfaces facing each other and extending parallel to the YZ plane. It has a reflection surface 22a and a second total reflection surface 22b. Here, it is assumed that the first total reflection surface 22a is on the side close to the image forming apparatus 10 and the second total reflection surface 22b is on the side far from the image forming apparatus 10. In this case, the first total reflection surface 22a is a common surface portion with the light incident surface IS and the light exit surface OS. Accordingly, part or all of the light incident surface IS and the light exit surface OS also function as the light guide D2 that guides image light. The image light reflected by the incident light folding surface 21 of the light incident part D1 first enters the first total reflection surface 22a and is totally reflected. Next, the image light enters the second total reflection surface 22b and is totally reflected. Hereinafter, by repeating this operation, the image light is guided to the back side of the light guide plate 20, that is, the + Z side provided with the image extraction unit 23 (see, for example, FIG. 2A). Here, the refractive index n of the transparent resin material used for the light guide D2 is, for example, a high refractive index material of 1.5 or more. By using a transparent resin material having a relatively high refractive index for the light guide plate 20, it becomes easier to guide the image light inside the light guide plate 20, and the angle of view of the image light inside the light guide plate 20 is made relatively small. be able to.

  The light emission part D3 has an image extraction part 23 having a fine structure facing the light emission surface OS. The image extraction unit 23 is formed on the back side (+ Z side) of the total reflection surface forming unit 22 so as to be close to the extension plane substantially along the extension plane of the second total reflection surface 22b. The image light that has passed through the forming portion 22 is reflected at a predetermined angle and bent toward the light exit surface OS. The detailed structure of the image extraction unit 23 will be described later with reference to FIG.

[B. (Optical path of image light)
Hereinafter, the optical path of the image light will be described. As shown in FIG. 1A, the main components of the image lights GL1, GL2, and GL3 that have passed through the projection optical system 12 are incident from the light incident surface IS of the light guide plate 20, respectively, and then the first and second all components. Total reflection is repeated at different angles on the reflecting surfaces 22a and 22b. Of the image light GL1, GL2, and GL3, the image light GL1 emitted from the central portion of the emission surface 32a of the liquid crystal device 11 is reflected by the incident light folding surface 21 and then taken out through the total reflection surface forming unit 22. The light is reflected by the central portion 23k of the portion 23 and emitted from the light exit surface OS in the direction of the optical axis AX perpendicular to the surface. Further, the image light GL2 emitted from one end side (+ Z side) of the emission surface 32a of the liquid crystal device 11 passes through the total reflection surface forming unit 22 and is a peripheral portion on the counter light incident surface side (+ Z side) of the image extraction unit 23. The light is reflected at 23 m and emitted from the light exit surface OS in a predetermined angular direction. The image light GL3 emitted from the other end side (−Z side) of the emission surface 32a of the liquid crystal device 11 passes through the total reflection surface forming unit 22 and is the most light incident surface side (−Z side) of the image extraction unit 23. ) And is emitted from the light exit surface OS in a predetermined angle direction. In this case, with respect to the total reflection angles of the image lights GL1, GL2, and GL3, the angle of the image light GL2 is the smallest, the angle of the image light GL3 is the largest, and the angles of the other image lights are The intermediate value of.

  Further, since the light reflection efficiency due to the total reflection at the first and second total reflection surfaces 22a and 22b is very high, the luminance is hardly lowered until the image extraction unit 23 is reached. Further, as shown in FIG. 1B, the image light GLY that is image light viewed in the vertical direction, that is, the Y direction passes through the light guide plate 20 so as to converge as a whole light flux.

[C. The structure of the image extraction part and the bending of the optical path by the image extraction part)
Hereinafter, the detailed structure of the image extraction part 23 of the light-guide plate 20 which concerns on this embodiment is demonstrated. As shown in FIGS. 2A and 2B, the image extraction unit 23 includes a large number of image light reflecting surfaces 23a, and the direction in which the image light reflecting surfaces 23a are arranged is the total reflection surface forming unit 22. The Z direction extends. Each image light reflecting surface 23a is an elongated surface extending in the vertical direction perpendicular to the Z direction, that is, in the Y direction. The multiple image light reflecting surfaces 23a are parallel to each other, have the same angle with respect to the first and second total reflection surfaces 22a and 22b, respectively, and transmit part of the light components of the image light and reflect the rest. It is a partially reflecting surface. Thereby, the image extraction part 23 makes it possible to make an observer observe an external field image see-through. The image light reflecting surfaces 23a are connected by a boundary portion 23b that does not have a function as a reflecting surface or the like for extracting image light. As a result, the image light reflecting surfaces 23a are arranged periodically and repeatedly along the Z direction with the Y direction as the longitudinal direction, and extend parallel to each other. Here, one image light reflection surface 23a and one boundary portion 23b adjacent to the image light reflection surface 23a are referred to as a reflection unit 23c. That is, the entire reflection unit 23c has a single sawtooth shape in cross section.

  Here, the production of the image extraction unit 23 configured as described above will be briefly described. First, as a premise, the resin-made main body part including the total reflection surface forming part 22 and the image extracting part 23 in the light guide plate 20 is a pair of second parts forming a −X side part and a + X side part, respectively. It is comprised by 1 and 2nd resin member B1, B2. The image extraction part 23 is formed by sandwiching each image light reflection surface 23a on an inclined surface having a sawtooth cross section as a pair of bonding surfaces corresponding to the pair of resin members B1 and B2. For example, the image extraction unit 23 first forms a reflection film on a portion to be the image light reflection surface 23a in the inclined surface having a sawtooth cross section of the first resin member B1, and then the first and second resin members B1. , B2 are produced by bonding the inclined surfaces having a sawtooth cross section.

Hereinafter, the bending of the optical path of the image light by the image extraction unit 23 will be described. Here, among the image light, the image light GL2 and the image light GL3 that enter the both ends of the image extraction unit 23 are shown, and the other optical paths are the same as those described above, and thus the illustration and the like are omitted. Each image light reflection surface 23a is an actual incident surface of the image light GL2 and GL3. In this specification, the total reflection angle of the image light on the total reflection surfaces 22a and 22b is the incident angle with respect to the image extraction unit 23. That is, it is called an incident angle to the reflection unit 23c. As described above, the image light including the image lights GL2 and GL3 enters the light guide plate 20 shown in FIGS. 1A and 1B from the light incident surface IS and is shown in FIG. 2A and the like. As described above, the first and second total reflection surfaces 22 a and 22 b of the total reflection surface forming unit 22 are repeatedly guided by total reflection and reach the image extraction unit 23. First, as shown in FIG. 2A, the image light GL2 totally reflected by the first and second total reflection surfaces 22a and 22b of the total reflection surface forming unit 22 at the minimum reflection angle α ₋ After passing through N 23 times (N is a natural number greater than 1), the image light reflecting surface 23a located on the farthest side (+ Z side) of the peripheral portion 23m in the image extracting portion 23 is reached, and the image light reflecting surface 23a Is reflected from the light exit surface OS toward the eye EY at an angle θ ₂ with respect to the optical axis AX that is the central axis of the eye EY. Like the image light GL2, the component reflected on the back side of the image extraction unit 23 passes through a large number of image light reflection surfaces 23a one or more times and then is directed to the eye EY. 23a, and the component reflected here becomes an effective component and is recognized by the observer.

On the other hand, as shown in FIG. 2B, the image light GL3 totally reflected by the first and second total reflection surfaces 22a and 22b of the total reflection surface forming unit 22 at the maximum reflection angle α ₊ 23 reaches the image light reflecting surface 23a located closest inlet side of the peripheral portion 23h (-Z side) of the, by the reflection of the image light reflecting surface 23a, the light exit plane at an angle theta ₃ with respect to the optical axis AX OS To the eye EY.

Incidentally, the angle theta ₂ and the angle theta ₃ of the image light GL3 of the image light GL2 is a magnitude substantially equal opposite, it has become equivalent to the field angle of the virtual image due to the image light.

[D. The optical path of the light passing through the image extraction unit]
As described above, for example, components extracted from the back side of the image extraction unit 23 typified by the image light GL2 out of the image light pass through the image light reflecting surface 23a at least once before being extracted by the image extraction unit 23. To do. Here, the image extraction unit 23 sandwiches the image light reflection surface 23a between the pair of first and second resin members B1 and B2 disposed on the + X side and the −X side. Therefore, it is very important that there is no difference in refractive index between the resin members B1 and B2 so that unintended refraction does not occur when the image light passes through the image light reflecting surface 23a. If, as shown in FIG. 3, when the first resin member B1 is the refractive index difference between the second resin member B2, the image light GLx image light incident on the image light reflecting surface 23a at an incident angle phi ₁ Unintentional refraction occurs when passing through the reflecting surface 23a. As a result, the image light GLx propagates through the image extraction unit 23 at a refraction angle φ ₂ (φ ₁ ≠ φ ₂ ), and this angular deviation appears as image degradation. In particular, when the image light reflection surface 23a in which a plurality of image lights GLx are arranged crosses at a time, the deterioration of the image due to the angle shift further proceeds. Regarding the refractive index difference that causes the angular deviation as described above, for example, if the refractive index difference between the resin members B1 and B2 is 0.001 or more, there is a possibility that the observer will recognize that the image light is shifted. . Therefore, very high accuracy is required to make the difference in refractive index within a range of about ± 0.0005. Limiting the difference in refractive index at this level cannot be guaranteed even if the same material is used for the first resin member B1 and the second resin member B2, and a difference more than this occurs due to manufacturing errors. Get. In the present embodiment, among the manufacture of the light guide plate 20, particularly in the manufacture of the image extraction unit 23, the light guide plate 20 is made highly accurate so as to suppress the occurrence of unintentional refraction as described above. As a result, the virtual image display device 100 can form a good image.

[E. Method for manufacturing light guide plate]
Hereinafter, with reference to FIG.4 and FIG.5 (A) -5 (E), the manufacturing method of the light-guide plate which concerns on this embodiment is demonstrated. FIG. 4 is a flowchart for explaining the outline of the method for manufacturing the light guide plate 20 according to this embodiment. FIG. 5A is a plan view schematically showing the light guide plate 20 manufactured by the manufacturing method of the present embodiment. FIG. 5B shows the first and second resin members B1 and B2 which are the main portions of the total reflection surface forming portion 22 and the image extracting portion 23 in the light guide plate 20 shown in FIG. 5 (C) to 5 (E) are diagrams illustrating a process of forming the image extraction unit 23.

  First, as the first step of the manufacturing procedure of the light guide plate 20 shown in the flowchart of FIG. 4, the first and second resin members that are a set of metal molds for injection molding the first and second resin members B1 and B2. Molds MP1 and MP2 are prepared (the mold preparation process in step S1 in FIG. 4). Here, the set of resin member molds MP1 and MP2 has a first molding part PP1 for molding the first resin member B1 and a second molding part PP2 for molding the second resin member B2. is doing. The resin member mold MP1 has transfer surfaces SS1 and SS2 having a sawtooth cross section for forming a large number of reflection units 23c of the image extraction portion 23 among the first and second molding portions PP1 and PP2. In other words, the transfer surface SS1 and the transfer surface SS2 have the same shape, and these are used as the surfaces to be bonded, and a plurality of reflection units 23c of the image extraction unit 23 are formed by bonding them while providing a reflective film therebetween. Is done. The resin member molding die MP2 has a transfer surface SSa for forming flat surfaces such as total reflection surfaces 22a and 22b of the total reflection surface forming portion 22. As described above, in the resin member molding dies MP1 and MP2, since the pair of first and second molding parts PP1 and PP2 are both present in one mold, the pair of first and second resin members B1, B2 can be simultaneously produced in a batch. Thereby, since the error at the time of manufacture of the 1st resin member B1 and the 2nd resin member B2 can be suppressed as much as possible, the refractive index difference between the two is within a desired range (for example, within ± 0.0005). Can be accurate. Here, the simultaneous production of a plurality of members at the same time in this way is said to be produced in the same lot.

  Next, the prepared resin member molds MP1 and MP2 are closed and further clamped, and a resin material is injected and filled into the internal space formed between the resin member molds MP1 and MP2 at a high pressure. (Injection filling step of step S2 in FIG. 4). As a result, the same resin material is filled in both the first molding part PP1 and the second molding part PP2. The resin material filled in the first and second molding parts PP1 and PP2 is maintained in a pressurized state in one set of resin member molding dies MP1 and MP2 and gradually cooled, whereby the resin member molding die MP1. , MP2 transfer surfaces SS1, SS2, SSa are transferred. After the transfer, the resin material is released from the resin member molds MP1 and MP2 (the release step in step S3 in FIG. 4). By the above, both resin members B1 and B2 are produced from the resin material in the same lot (resin member molding step). In the first and second resin members B1 and B2 manufactured through the above-described steps, the molding surface PS1 and the molding surface PS2 which are sawtooth-shaped surfaces formed by transfer of the transfer surfaces SS1 and SS2 are: They have the same shape and are axisymmetric with respect to the Y direction, which is the direction in which a large number of reflection units 23c extend. The molding surfaces PS1 and PS2 are formed by connecting a plurality of groove portions or mountain portions having the same shape including inclined surfaces parallel to each other for constituting the image light reflecting surface 23a of each reflecting unit 23c. Can also be seen.

  Here, with respect to the molding surfaces PS1 and PS2, the molding surface PS2 of the second resin member B2 is inverted by 180 ° with the Y direction as the axial direction so that the molding surface PS1 of the first resin member B1 is reversed. It is a shape that can be bonded together without a gap. The first resin member B1 constitutes a main body portion on the −X side of the total reflection surface forming portion 22 and has a first total reflection surface 22a, and is disposed to face the image extraction portion 23. The light exit surface OS is provided. Further, the second resin member B2 has a second total reflection surface 22b as a constituent of the main body portion on the + X side of the total reflection surface forming portion 22.

  Next, as shown in FIG. 5C, the image light reflecting surface 23a of the molding surface PS1 of the first resin member B1 produced in the resin member molding process faces the first surfaces M1 that should constitute the image light reflecting surface 23a. From the arrow direction AW, which is the direction, a film-forming material such as aluminum is vapor-deposited, and the reflection film MB to be the image light reflection surface 23a is formed on each first surface M1 (the reflection film formation in step S4 in FIG. 4). Membrane process). Next, as shown in FIGS. 5D and 5E, each first surface M1 of the molding surface PS1 on which the image light reflecting surface 23a is formed and each molding surface PS2 corresponding to the molding surface PS1. The image extraction part 23 of the light-guide plate 20 is formed by bonding the two surfaces M2 (image extraction part forming step). Bonding is performed by adhesion between the molding surface PS1 and the molding surface PS2. At this time, the total reflection surface forming portion 22 is also formed by the first and second resin members B1 and B2. Furthermore, as shown in FIG. 5A, by joining a rectangular block-shaped thick block portion BP including the light incident surface IS and the like to the one formed by both resin members B1 and B2, the light guide plate 20 A resin main body is produced (resin member joining step in step S5 in FIG. 4), and the incident light folding surface 21 is formed in the block part BP, whereby the light guide plate 20 is produced.

  As described above, in the method of manufacturing the light guide plate 20 of the present embodiment, the resin member having both the first molded portion PP1 and the second molded portion PP2 in the resin member molding step shown in steps S2 and S3 of FIG. A pair of first and second resin members B1 and B2 are molded together by the molding dies MP1 and MP2. Further, in the image extraction portion forming step shown in step S5 of FIG. 4, the image extraction portion 23 is formed by bonding the first and second resin members B1 and B2. In this case, the refractive index difference between the first resin member B1 and the second resin member B2 constituting the image extraction portion 23 can be suppressed as much as possible. Therefore, the light guide plate 20 capable of displaying a good image is manufactured by suppressing the angular deviation of the image light due to unintentional refraction inside the image extraction unit 23.

[Second Embodiment]
Hereinafter, a second embodiment obtained by modifying the first embodiment will be described. In addition, the manufacturing method of the light-guide plate which concerns on this embodiment is a modification of the manufacturing method of the light-guide plate of 1st Embodiment, About manufacturing processes other than the manufacturing process of the resin-made main-body parts which comprise a light-guide plate, Since it is the same as that of 1st Embodiment, only the resin member which is a resin member shaping | molding die and the resin-made main-body parts shape | molded by the said mold is demonstrated, and description and illustration are abbreviate | omitted about others. The same reference numerals as those in the first embodiment have the same functions unless otherwise specified.

  FIG. 6A is a plan view schematically showing the light guide plate 20 manufactured by the manufacturing method of the present embodiment. FIG. 6B shows the first and second resin members B1 and B2 that are the main body of the image extraction portion 23 in the light guide plate 20 shown in FIG. It is a figure which shows 1 set of resin member shaping | molding die MP1, MP2 which shape | molds 3rd resin member B3 which is a main-body part by injection molding.

  In the method for manufacturing the light guide plate 20 according to the present embodiment, the pair of resin member molding dies MP1 and MP2 molds the first molding part PP1 for molding the first resin member B1 and the second resin member B2. In addition to the second molding part PP2 for the purpose, it has a third molding part PP3 for molding the third resin member B3. That is, in the resin member molding dies MP1 and MP2, the first, second and third molding members PP1, PP2 and PP3 are present in one mold, so that the first, second and third resin members B1, B2 are present. , B3 can be produced in the same lot.

  Here, in the example shown in FIG. 6B, the first resin member B1 and the second resin member B2 form only the main body portion of the image extraction portion 23 of the light guide plate 20, and are formed by the third resin member B3. Portions such as total reflection surfaces 22a and 22b and light exit surface OS of the total reflection surface forming portion 22 are formed. Thus, by having the 3rd molding part PP3, while increasing the freedom degree of the shape of 1st and 2nd resin member B1, B2, 1st, 2nd and 3rd resin member B1, B2, B3 are made the same. By producing in a lot, the light guide plate 20 having the high-precision light emission part D3 can be produced while suppressing the difference in refractive index between the main body part of the light emission part D3 and the image extraction part 23.

  As described above, in the method for manufacturing the light guide plate 20 of the present embodiment, the resin member molding dies MP1 and MP2 having the first molded part PP1, the second molded part PP2, and the third molded part PP3 in the resin member molding process. As a result, the pair of first, second and third resin members B1, B2 and B3 are molded together. Further, the first and second resin members B1 and B2 are bonded together to form one image extraction portion 23. Therefore, the light guide plate 20 capable of displaying a good image is manufactured by suppressing the angular deviation of the image light due to unintentional refraction inside the image extraction unit 23.

[Third Embodiment]
Hereinafter, a third embodiment obtained by modifying the first embodiment will be described. The light guide plate manufacturing method according to the present embodiment is a modification of the light guide plate manufacturing method according to the first embodiment, and manufacturing steps other than the image extraction unit manufacturing step are the same as those in the first embodiment. Therefore, only the molding of the resin member constituting the image extraction unit is shown, and the explanation and illustration of the other steps are omitted. The same reference numerals as those in the first embodiment have the same functions unless otherwise specified.

  FIG. 7 is a flowchart for explaining the outline of the method for manufacturing the light guide plate 20 according to this embodiment. FIG. 8A is a plan view schematically showing the light guide plate 20 manufactured by the manufacturing method of the present embodiment. 8B shows a resin molded product BX to be the first and second resin members B1 and B2 which are the main body of the image extraction portion 23 in the light guide plate 20 shown in FIG. It is a figure which shows 1 set of resin member shaping | molding die MP1, MP2 shape | molded by injection-molding the molded article BX. Further, in FIGS. 9A to 9C, the resin molded product BX is divided to take out the first and second resin members B1 and B2, and the first and second resin members B1 and B2 are bonded together. It is a figure which shows a mode that one image extraction part 23 forms. Here, the first resin member B1 and the second resin member B2 have the same shape, and the resin molded product BX includes a plurality of first resin members B1 or second resin members B2 (see FIG. 9A). In the example shown, 3 × 6 = 18 sheets) have a saw-toothed cross section. That is, a plurality of first and second resin members B1 and B2 are taken out by dividing the resin molded product BX.

  In the method for manufacturing the light guide plate 20 according to the present embodiment, the set of resin member molding dies MP1 and MP2 shown in FIG. 8B includes the first and second resin members B1 and B2 constituting the image extraction unit 23. The resin molded product BX is formed. That is, first, the first and second resin member molding dies MP1 and MP2 for injection molding the resin molded product BX are prepared (the mold preparation process in step S1 of FIG. 7), and then the resin in the clamped state. The same resin material injected at a high pressure is filled in the internal space formed between the member molds MP1 and MP2 at the same time (injection filling step of step S2 in FIG. 7). The resin material is pressed and held in the first and second resin member molds MP1 and MP2 and gradually cooled, and then released from the resin member molds MP1 and MP2 (release in step S3 in FIG. 7). Process). As described above, the resin molded product BX having a sawtooth cross section is molded (resin member molding process). Next, as shown in FIG. 9A, by cutting the molded resin molded product BX along the cut surface DS, the first and second resin members B1 having the same shape shown in FIG. , B2 are taken out (resin molded product dividing step in step S3a in FIG. 7). That is, the first and second resin members B1 and B2 are molded in the same lot. At this time, the first resin member B1 and the second resin member B2 are taken out from adjacent portions of the resin molded product BX. That is, the first resin member B1 and the second resin member B2 are molded in a continuous state. Thereby, the difference in refractive index between the two can be further reduced. In the above case, as shown in FIG. 8 (B), the corresponding first molding part PP1 and second molding part PP2 are one mold continuous to adjacent parts in the resin member molding dies MP1 and MP2. It will be included as a part.

  Next, as shown in FIGS. 9B and 9C, a film forming material such as aluminum is deposited on the first resin member B1 from the arrow direction AW (reflection film forming step in step S4 in FIG. 7). Then, the molding surface PS1 of the first resin member B1 and the molding surface PS2 of the second resin member B2 are bonded together to form the image extraction portion 23 having a large number of image light reflection surfaces 23a (image extraction portion forming step). As described above, the image extraction portion 23 of the light guide plate 20 is produced.

  As shown in FIG. 8A, the resin member B3 and the block portion BP constituting the total reflection surface forming portion 22 and the like are joined to the image extraction portion 23 manufactured as described above (FIG. 7). In step S5, the light guide plate 20 is manufactured. In addition, about the resin member B3, it is good also as what is produced by the same lot similarly to the case of 2nd Embodiment.

  As described above, in the method of manufacturing the light guide plate 20 of the present embodiment, in the resin member molding step, the resin member molding dies MP1 and MP2 having the first molding part PP1 and the second molding part PP2 are collectively used as a pair. The first and second resin members B1 and B2 are molded. Further, the first and second resin members B1 and B2 are bonded together to form one image extraction portion 23. Therefore, the light guide plate 20 capable of displaying a good image is manufactured by suppressing the angular deviation of the image light due to unintentional refraction inside the image extraction unit 23.

[Fourth Embodiment]
Hereinafter, a fourth embodiment obtained by modifying the first embodiment will be described. The light guide plate manufacturing method according to the present embodiment is a modification of the light guide plate manufacturing method according to the first embodiment, and the manufacturing process other than the manufacturing process of the resin member serving as the main body portion of the image extraction unit is described below. Since it is the same as that of the first embodiment, only the molding of the image extraction portion is shown, and the explanation and illustration of the other steps are omitted. The same reference numerals as those in the first embodiment have the same functions unless otherwise specified.

  FIG. 10A and FIG. 10B show the step of molding the first and second resin members B1 and B2 that are the main body portion of the image extraction portion 23 in the light guide plate manufacturing method according to the present embodiment. FIG.

  In the manufacturing method of the light guide plate 20 according to the present embodiment, the first and second resin members B1 and B2 are manufactured by ultraviolet curable resin molding. That is, the first molding part PP1 for molding the first resin member B1 and the second resin member B2 for molding the first resin member B1 by the metal member resin member molding die MP1 and the light-transmitting glass substrate GP. The two molded parts PP2 are formed, and the first and second resin members B1 and B2 can be manufactured in the same lot in cooperation with each other. Specifically, first, as shown in FIG. 10A, the ultraviolet curable resin MM is simultaneously filled on the resin member molding die MP1 having the transfer surfaces SS1 and SS2 having a sawtooth cross-sectional surface. Next, as shown in FIG. 10B, the glass substrate GP is pressed from above the resin member mold MP1 to transfer the transfer surfaces SS1 and SS2 of the resin member mold MP1 (transfer process). The ultraviolet ray UV is irradiated (ultraviolet light irradiation step), the ultraviolet curable resin MM is cured (resin curing step), and the first and second resin members B1 and B2 to which the transfer surfaces SS1 and SS2 are transferred are molded.

  As described above, in the manufacturing method of the light guide plate of the present embodiment, a pair is collectively formed by ultraviolet curable resin molding that can relatively easily produce a fine shape by using the resin member molding die MP1 and the glass substrate GP. The first and second resin members B1 and B2 are molded. Further, the first and second resin members B1 and B2 are bonded together to form one image extraction portion 23. Therefore, the light guide plate 20 capable of displaying a good image is manufactured by suppressing the angular deviation of the image light due to unintentional refraction inside the image extraction unit 23. In the illustrated example, the resin member molding die MP1 has two transfer surfaces SS1 and SS2 to mold the first and second resin members B1 and B2. For example, in the third embodiment, FIG. As in the resin member molding die MP1 shown in (B), a resin molded product BX in which a large amount of the first and second resin members B1 and B2 can be formed at a time may be molded.

[Others]
Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  In the above description, a plurality of groove portions including inclined surfaces parallel to each other for forming the image light reflection surface 23a of each reflection unit 23c are the same in the molding surface PS1 and the molding surface PS2 which are sawtooth cross-sectional surfaces. The shape is assumed to be. In other words, each reflection unit 23c has the same shape, but the image light reflection surface 23a may have a different size as long as the inclination angle is maintained. That is, these molding surfaces PS1 and PS2 may be sawtooth-shaped surfaces formed by connecting similar-shaped groove portions.

  In the above description, a configuration having a large number of reflection units is used. However, for a configuration in which image light is extracted from one reflection surface, a light guide plate is manufactured by joining two block portions as in this configuration. May be.

  In the above description, the transmissive liquid crystal device 11 is used as the image display element. However, the image display element is not limited to the transmissive liquid crystal device, and various devices can be used. For example, a configuration using a reflective liquid crystal panel is possible, and a digital micromirror device or the like can be used instead of the liquid crystal device 11. Moreover, the structure using the self-light-emitting element represented by LED array, OLED (organic EL), etc. is also possible. Furthermore, a configuration using a laser scanner in which a laser light source and a polygon mirror or other scanner are combined is possible. In the liquid crystal device 11 and its light source, the luminance pattern can be adjusted in consideration of the light extraction characteristics of the image extraction unit 23.

  In the above description, the virtual image display device 100 includes the image forming device 10 and the light guide plate 20 one by one corresponding to both the right eye and the left eye, but either the right eye or the left eye. Only the image forming apparatus 10 and the light guide plate 20 may be provided so that the image is viewed with one eye.

  In the above description, a see-through type virtual image display device is described. However, when it is not necessary to observe an external image, the light reflectance of the image light reflecting surface 23a can be set to approximately 100%.

  In the above description, the light incident surface IS and the light exit surface OS are arranged on the same plane. However, the present invention is not limited to this. For example, the light incident surface IS is the same plane as the first total reflection surface 22a. It is also possible to dispose the light emitting surface OS on the same plane as the second total reflection surface 22b.

  In the above description, the angles of the mirror layer 21a and the inclined surface RS that constitute the incident light folding curved surface 21 are not particularly mentioned. It can be set to any value.

  In the above description, the V-shaped groove formed by the reflection unit 23c is illustrated with the tip sharpened. However, the shape of the V-shaped groove is not limited to this, and the tip is cut flat. It may be one that has an R or a tip.

  In the above description, the virtual image display device 100 of the embodiment has been specifically described as a head-mounted display. However, the virtual image display device 100 of the embodiment can be modified to a head-up display.

  In the above description, in the first and second total reflection surfaces 22a and 22b, image light is totally reflected and guided by the interface with air without applying a mirror, a half mirror, or the like on the surface. The total reflection in the present invention includes reflection formed by forming a mirror coat or a half mirror film on the whole or a part of the first and second total reflection surfaces 22a and 22b. For example, the case where the incident angle of the image light satisfies the total reflection condition and the whole or a part of the total reflection surfaces 22a and 22b is mirror-coated to reflect substantially all the image light. . Moreover, as long as image light with sufficient brightness can be obtained, the whole or a part of the total reflection surfaces 22a and 22b may be coated with a somewhat transmissive mirror.

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 11 ... Liquid crystal device, 12 ... Projection optical system, 20 ... Light guide plate, 20a ... Light guide plate main-body part, 21 ... Incident light folding surface, 22 ... Total reflection surface formation part, 22a ... 1st all Reflecting surface, 22b ... second total reflecting surface, 23 ... image extracting unit, 23a ... image light reflecting surface (partial reflecting surface), 23c ... reflecting unit, 100 ... virtual image display device, AX ... optical axis, B1 ... first Resin member, B2 ... second resin member, B3 ... third resin member, D1 ... light incident part, D2 ... light guide part, D3 ... light emission part, EY ... eye, GL1, GL2, GL3, GLx, GLy ... image Light, IS ... light incident surface, OA ... optical axis, OS ... light emitting surface, MP1, MP2 ... resin member molding die, PP1 ... first molding part, PP2 ... second molding part, SP1, SP2 ... molding surface, SS1 , SS2, SSa ... transfer surface

Claims (8)

A light guide plate comprising: a light guide unit; a light incident unit that causes image light to enter the light guide unit; and a light emitting unit that includes an image extraction unit that extracts the image light guided by the light guide unit to the outside. A manufacturing method comprising:
A first molding part that molds a first resin member that constitutes a part of the image extraction part, and a second resin member that forms a pair with the first resin member and constitutes another part of the image extraction part A mold preparation step of preparing a resin member mold having both of the second molding part and
Resin member molding in which both the first molding portion and the second molding portion of the resin member molding die are filled with a resin material, and the first and second resin members are collectively molded from the resin member molding die. Process,
An image extraction portion forming step of forming the image extraction portion by bonding the first resin member and the second resin member formed together in the resin member molding step as a pair. Production method.   In the image extraction portion forming step, in order to form a plurality of reflection units arranged in a predetermined arrangement direction constituting the image extraction portion between the first resin member and the second resin member, The method for manufacturing a light guide plate according to claim 1, further comprising a reflective film forming step of forming a reflective film on one of the molding surfaces of the first and second-position resin members bonded to each other.   The plurality of reflection units have a plurality of partial reflection surfaces that transmit at least a part of incident light by the reflection film, and at least a part of the image light is transmitted once in any of the plurality of partial reflection surfaces. The manufacturing method of the light-guide plate of Claim 2 made to pass above. The first resin member and the second resin member have a pair of sawtooth surfaces in cross section that are mutually inverted including inclined surfaces parallel to each other for constituting the plurality of reflection units,
In the image extraction portion forming step, the longitudinal direction of the reflection unit is set as the axial direction, the cross-sectional sawtooth surface of the second resin member is inverted by 180 ° and bonded to the cross-sectional sawtooth surface of the first resin member. The manufacturing method of the light-guide plate of Claim 3.   The resin member molding die includes both the first molding part and the second molding part as a part of one continuous mold, and the first and second resin members are formed of the resin member molding. The method for manufacturing a light guide plate according to any one of claims 1 to 4, wherein the light guide plate is molded in a continuous state in the process, and is individually divided before the image extraction part forming process.   The said resin member shaping | molding die further has the 3rd shaping | molding part which shape | molds the 3rd resin member which comprises the main-body part of the said light emission part which joins the said image extraction part. The manufacturing method of the light-guide plate of one term. The light-guide plate manufactured by the manufacturing method of the light-guide plate as described in any one of Claim 1- Claim 6. The light guide plate according to claim 7;
An image forming apparatus that forms the image light guided to the light guide plate;
A virtual image display device.

Images