JP2012198263A - Light guide plate, virtual image display provided with the same, and method for manufacturing light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate for a virtual image display that can be prepared in a relatively simple manner and that has high optical performance, and a virtual image display including the light guide plate, and to provide a method for manufacturing the light guide plate.SOLUTION: A first block section B1 and a second block section B2 are individually prepared and are bonded together. Hence, sink generation is prevented in the preparation of the block sections B1 and B2, thereby making it possible to prepare a thick section TT having high optical performance as a light guide plate 20 in a relatively simple manner. Further, at this time, the thick section TT serves as a light incident section D1 so that the light guide plate 20 is capable of drawing more image light in the light incident section D1. Moreover, a virtual image display 100 including the light guide plate 20 can be manufactured with relatively high precision in a relatively simple manner.

Description

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

  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).

  When a light beam is extracted from a light guide plate having a large number of parallel partial reflection surfaces as described above, it is necessary to make the light incident side portion of the light guide plate thicker than other portions in order to capture more light. Thus, it is not easy to produce a member having a difference in thickness, and when the light guide plate is formed by, for example, injection molding, sinks in which the molding surface is retracted from the mold surface easily occur due to shrinkage. The generated sink becomes a factor that degrades the optical performance of the light guide plate.

JP 2004-157520 A

  The present invention has been made in view of the above problems of the background art, and provides a light guide plate for a virtual image display device that can be relatively easily created and has high optical performance, and a virtual image display device incorporating the same. The purpose is to do. Moreover, it aims at providing the manufacturing method of the said light-guide plate.

  In order to solve the above problems, 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 guide plate comprising: (b) a first block portion that constitutes at least a part of the light incident portion; and (c) a second block portion that constitutes at least a part of the light guide portion. And (d) a joining portion that joins the first block portion and the second block portion, and (e) light is incident in a state where the first block portion and the second block portion are joined by the joining portion. Part, light guide part and light emitting part are incorporated in the first block part and the second block part, at least the first block part forms a thick part relatively thicker than other parts, The thick part functions as a light incident part.

  The light guide plate is formed by individually manufacturing a first block portion and a second block portion and joining them. Thereby, in the production of each block, the occurrence of sink marks and the like can be suppressed and the shape accuracy can be ensured, so that a light incident part, a light guide part and the like having high optical performance can be produced relatively easily. At this time, since the thick portion has the light incident portion, the light guide plate can capture more image light at the light incident portion.

  In a specific aspect of the present invention, (a) the light guide unit has first and second total reflection surfaces extending opposite to each other, and the image light taken from the light incident unit is supplied to the first and second image lights. Guided by total reflection on the total reflection surface, (b) the light emitting unit has a plurality of reflection units arranged in a predetermined arrangement direction, and image light incident through the light guide unit is transmitted through the plurality of reflection units. And an image extraction portion that can be extracted to the outside by bending. Here, total reflection is not only the case where all the light is reflected and transmitted by the inner surface, but also a mirror coating or a half mirror film made of a semi-transmissive aluminum film on the surface that satisfies the total reflection condition. It also includes the case of reflection. In this case, the first and second total reflection surfaces of the light guide unit guide the image light using total reflection, and the image output unit of the light emission unit reflects the image light and extracts it from the light guide plate. it can.

  In still another aspect of the present invention, each of the reflection units constituting the plurality of reflection units is configured with a first reflection surface and a second reflection surface that forms a predetermined angle with respect to the first reflection surface, respectively. The image light guided by the light guide unit is reflected by the first reflecting surface, and the image light reflected by the first reflecting surface is further reflected by the second reflecting surface to bend the optical path. In this case, the image light can be extracted by two-stage reflection between the first reflecting surface and the second reflecting surface.

  In still another aspect of the present invention, (a) the thick portion is formed by the first block portion, and (b) at the joint portion, the joint surface of the first block portion and the joint surface of the second block portion are: It is perpendicular | vertical with respect to the light guide direction in a light guide part. In this case, it is possible to increase the accuracy of each part by making the first block part and the second block part into a simple shape, and it is possible to suppress the light passing through the joint surface from being affected by the angle change. .

  In still another aspect of the present invention, the thick portion is formed by the first block portion and a part of the second block portion. In this case, a plurality of members having relatively thin thicknesses can be combined to form a thick portion that is relatively thicker than the other portions.

  In still another aspect of the present invention, (a) the light guide has first and second total reflection surfaces extending opposite to each other, and (b) the first block portion and the second block portion The light incident part is divided by a surface obtained by extending one of the first and second total reflection surfaces. In this case, the second block portion has a shape with no difference in thickness on the basis of the width or interval between the first total reflection surface and the second total reflection surface, and is easy to process with high accuracy.

  In still another aspect of the present invention, the first block portion and the second block portion include a light incident surface that takes in image light from the outside of the light incident portion, and the image light that is taken in and taken in from the incident image light. The thick portion is divided by a surface passing through the boundary with the incident light folding curved surface that is folded back to the light guide portion side. In this case, each of the incident light folding surface and the light incident surface can be formed of a single member and can be made relatively accurate.

  In still another aspect of the present invention, the light guide plate further includes a positioning member for determining a relative positional relationship in joining the first block portion and the second block portion. In this case, the optical performance of the light guide plate can be improved by making the positional relationship between the first block portion and the second block portion precise.

  In still another aspect of the present invention, the positioning member is formed in a region outside the optical path of the image light. In this case, it is possible to avoid the positioning member from affecting the image light.

  In still another aspect of the present invention, the positioning part defines the thickness of the adhesive layer as the joint part. In this case, the positional relationship between the first block portion and the second block portion can be made more precise, and the strength and the like at the joint can be optimized.

  In still another aspect of the present invention, the main body portion of the first block portion and the main body portion of the second block portion are resin members respectively formed by injection molding. In this case, each block portion can be manufactured relatively simply and quickly, and thus the light guide plate can be manufactured efficiently.

  In order to solve the above problems, a virtual image display device according to the present invention includes (a) the light guide plate according to any one of the above, and (b) an image forming apparatus that forms image light guided to the light guide plate. In this case, by using any of the light guide plates described above, the virtual image display device can be easily manufactured with relatively high accuracy.

  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 method of manufacturing a light guide plate comprising a light emitting part to be emitted to the outside, wherein (b) a first block part that constitutes at least a part of the light incident part and a second part that constitutes at least a part of the light guide part. A block preparation step for preparing the block portion, and (c) a block joining step for joining the first block portion and the second block portion prepared in the block preparation step, and (d) by the block joining step. In a state where the first block portion and the second block portion are joined, the light incident portion, the light guide portion, and the light emitting portion are incorporated into the first block portion and the second block portion, and at least the first block portion is ,Relative Forming a thick portion which functions as a thick light entrance portion than other portions.

  In the method for manufacturing the light guide plate, the first block portion and the second block portion are separately prepared and joined together to form the light guide plate. Thereby, since the occurrence of sink marks in each block portion is suppressed, a light guide plate having a thick portion having high optical performance can be manufactured relatively easily. At this time, it is possible to capture more image light by forming the light incident portion thick.

  In a specific aspect of the present invention, the block preparation step includes an injection molding step of molding the main body portion of the first block portion and the main body portion of the second block portion by injection molding. In this case, the light guide plate can be manufactured relatively easily and quickly by injection molding.

(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 center part of the image extraction part in a light-guide plate, (B) is sectional drawing explaining the structure of the back | inner side part of an image extraction part, (C ) Is a cross-sectional view illustrating the structure of the portion on the inlet side of the image extraction unit. (A) is a figure which shows the 1st block part and 2nd block part before joining, (B) is a figure which shows the light-guide plate formed by joining. (A) is a figure which shows the state before joining of the 1st block part and 2nd block part which comprise the light-guide plate which concerns on 2nd Embodiment, (B) is the light-guide plate formed by joining. FIG. (A) is a top view which shows the state before joining of the 1st block part and 2nd block part which comprise the light-guide plate which concerns on 3rd Embodiment, (B) shows the light-guide plate after joining. It is a top view, (C) is a front view which shows the light-guide plate after joining, (D) is a back view. (A) is a figure which shows the state before joining of the 1st block part and 2nd block part which comprise the light-guide plate which concerns on 4th Embodiment, (B) is the light-guide plate formed by joining. FIG. (C) is a figure which shows the 1st block part and 2nd block part which comprise the light-guide plate of a modification. (A) is a figure for demonstrating the light-guide plate which concerns on 5th Embodiment, (B) is a figure which shows the state before joining of the 1st block part and 2nd block part which comprise a light-guide plate. (C) is a figure which shows the light-guide plate formed by joining. (A) is a figure for demonstrating the structure of the back | inner side part of the image extraction part of the image extraction part in the light guide plate which concerns on 6th Embodiment, (B) is the entrance side of an image extraction part. It is sectional drawing explaining the structure of a part. (A) And (B) is a figure for demonstrating the modification of a junction part, (C) And (D) is a figure for demonstrating the other modification of a junction part. (A) And (B) is a figure for demonstrating the further another modification of a junction part. (A)-(D) is a figure for demonstrating the modification of a positioning member, (E) is a figure for demonstrating the other modification of a positioning member.

[First Embodiment]
Hereinafter, a light guide plate for a virtual image display device according to a 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 FIG. 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 a reflecting surface incident light folding surface 21 and takes in the image light from the image forming apparatus 10 from the light incident surface IS, and the taken image light to the light guide part D2. Bend towards. That is, the light incident part D1 is a part having an optical meaning of capturing image light. 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. That is, the light guide portion D2 is a portion having a function in an optical sense of propagating image light. 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. . That is, the light emission part D3 is a part having an optical meaning of extracting image light. As described above, the light incident part D1, the light guide part D2, and the light emission part D3 are functional parts when viewed from the optical surface of the light guide plate 20.

  The light guide plate 20 is a structure mainly composed of a resin member. The light guide plate 20 constitutes a part that functions as the light incident part D1, the light guide part D2, and the light emission part D3, and includes a first block part B1 and a second block part. And a block portion B2. The first block portion B1 is a massive, thick quadrangular prism having a trapezoidal bottom surface, and includes a thick portion TT that functions as the light incident portion D1. The second block portion B2 has a flat plate shape and is formed with a total reflection surface forming portion 22 that mainly functions as the light guide portion D2. The second block portion B2 is formed by forming the image extraction portion 23 and the light emission surface OS of the light emission portion D3 on the downstream side of the light path of the light guide portion D2, that is, the back side (+ Z side). That is, the first and second block portions B1 and B2 are structural portions that form a thick portion or a flat plate portion. The function of the light guide D2 is mainly realized by the second block part B2 as described above, but the light incident surface IS of the light incident part D1 included in the first block part B1 also guides light. It functions as a part of the light guide D2. As described above, the light guide plate 20 includes the light incident part D1, the light guide part D2, and the light emission part D3, which are functional parts, and the first and second block parts B1, B2 that are structural parts. The entire structure is formed by joining the first block portion B1 and the second block portion B2 at the joint portion SS (see FIGS. 3A and 3B). That is, the joint portion SS is a structural portion that joins the first and second block portions B1 and B2 that are structural portions. As described above, the first and second block portions B1 and B2 and the joint portion SS are structural portions in the light guide plate 20 when viewed as an appearance or a structure. With this light guide plate 20, the image light formed by the image forming apparatus 10 can be guided in the + Z direction and emitted toward the observer's eye EY to be recognized as an image. The first and second block parts B1 and B2 are formed of a main body part by injection molding from the same refractive index and light-transmitting resin material, and a reflection film or the like is applied to the main body part, thereby providing a light incident part. The reflection part of D1 and the image extraction part 23 of the light emission part D3 are formed.

  Hereinafter, functional parts of the light guide plate 20, that is, the respective parts D1 to D3 will be described. First, 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. Further, 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 quadrangular columnar thick portion TT, and the 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 D2 is totally reflected to guide the image light incident inside from the light incident part D1 side which is the entrance side to the light emission part D3 side which is the back side, to the image extraction part 23 of the light emission part D3. A surface forming portion 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 where the image extraction unit 23 is provided. Here, the refractive index n of the transparent resin material used for the light guide D2, that is, used for the second block portion B2, 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.

  In the light emission part D3, the image extraction part 23 having a fine structure is arranged 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. Specifically, among the image lights 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 curved surface 21, and then the standard reflection angle α _0. in entering the second total reflection surface 22b of the total reflection surface forming portion 22, while maintaining the standard reflection angle alpha _0, the first and second total reflection surface 22a, for example, N times in 22b (N is a natural number ) After being totally reflected, it is reflected by the central portion 23k of the image extracting portion 23 and emitted from the light exit surface OS in the direction of the optical axis AX perpendicular to this surface. Further, the image light GL2 emitted from one end side (−Z side) of the emission surface 32a of the liquid crystal device 11 has, for example, NM times on the first and second total reflection surfaces 22a and 22b at the maximum reflection angle α ₊ . (M is a natural number) Totally reflected, reflected by the peripheral portion 23m on the side opposite to the light incident surface (+ Z side) of the image extraction portion 23, 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 is, for example, N + M times total reflection at the first and second total reflection surfaces 22a and 22b with the minimum reflection angle α ₋ . Then, it is reflected by the peripheral portion 23h closest to the light incident surface (−Z side) in the image extraction portion 23, and is emitted from the light exit surface OS in a predetermined angular direction.

  In addition, since the reflection efficiency of light by the total reflection at the first and second total reflection surfaces 22a and 22b is very high, the number of reflections differs between the image lights GL1, GL2, and GL3 as described above. However, such a difference in the number of reflections hardly causes a decrease in luminance. 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 structure of the image extraction unit 23 and the bending of the optical path of the image light by the image extraction unit 23 will be described with reference to FIGS.

  First, as illustrated in FIG. 2A, the image extraction unit 23 is configured by arranging a large number of elongated reflection units 23 c extending in the Y direction in the Z direction in which the total reflection surface forming unit 22 extends. Each reflection unit 23c has a first reflection surface 23a disposed on the back side, that is, the + Z side, and a second reflection surface 23b disposed on the entrance side, that is, the −Z side. Among these, at least the second reflection surface 23b is a partial reflection surface capable of transmitting a part of light, and allows an observer to observe an external image in a see-through manner. Each reflection unit 23c has a V shape or a wedge shape in the XZ sectional view by the adjacent first and second reflection surfaces 23a and 23b, and is periodically arranged and extends in parallel with each other. Note that the relative angle β between the first reflecting surface 23a and the second reflecting surface 23b is, for example, 54.7 ° in the specific example. For the production of the image extraction unit 23 having the above-described configuration, first, the inclined surface having the predetermined angle to be the first and second reflection surfaces 23a and 23b is formed by injection molding, and then A reflective film for functioning as a reflective surface is formed on the slope, and the formed film is filled with a resin material. Further, instead of filling with a resin material, another resin base material may be prepared and bonded to the above-described reflective film.

  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 first reflection surface 23a is an actual incident surface for image light. In this specification, the total reflection angle of the image light at the total reflection surfaces 22a and 22b is determined as the incidence on the image extraction unit 23. An angle, that is, an incident angle to the reflection unit 23c is referred to.

First, as shown in FIGS. 2A and 2B, the image light GL2 guided at the incident angle α ₊ having the largest total reflection angle out of the image light is the light incident surface IS of the image extraction unit 23. (Refer to FIG. 1 (A)). The light enters the one reflecting unit 23c arranged in the peripheral portion 23m on the + Z side farthest from the first, and is first reflected by the first reflecting surface 23a, and then the second reflecting surface. The light is reflected by 23b and emitted from the light exit surface OS shown in FIG. 1A and the like without passing through the other reflecting unit 23c. In other words, the image light GL2 is bent at a desired angle by only one pass through the image extraction unit 23, and is extracted to the observer side as virtual image light with a small loss. Further, as shown in FIGS. 2A and 2C, the image light GL3 guided at the incident angle α ₋ having the smallest total reflection angle is also reflected by the first reflecting surface 23a first, Next, the light is reflected by the second reflecting surface 23b.

Here, in the case of the two-stage reflection on the first and second reflecting surfaces 23a and 23b as described above, as shown in FIG. 2, the direction when each image light is incident and the direction when it is emitted The bending angle ψ, which is the angle formed, is ψ = 2 (R−β) (R: right angle), and is constant regardless of the values of the incident angles α ₀ , α ₊ , α _{− and the} like. As a result, the image light can be efficiently extracted in an angle state that collects the image light as a whole on the eyes EY of the observer.

Incidentally, the angle [delta] ₂ and the angle [delta] 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. (Multi-block structure of light guide plate)
Here, with respect to the light guide plate 20, in order to form an image, the light incident part D1 side needs to have a structure for capturing more light. For this reason, the light guide plate 20 of the present embodiment has a structure in which the first block portion B1 has a thicker portion TT that is relatively thicker than other portions in order to realize the light incident portion D1. At this time, the shape of the light incident surface IS and the inclined surface RS of the light incident portion D1 is required to be optically accurate for good image formation.

  On the other hand, on the light guide part D2 and the light emission part D3 side, high parallelism and flatness are required on the total reflection surfaces 22a and 22b of the total reflection surface forming unit 22 for good image formation, and the image extraction unit 23 is required. Such a fine structure requires a flatness and an inclination angle of a surface with high optical accuracy. For this reason, in the light guide plate 20 of the present embodiment, the second block portion B2 has a thin plate-like structure with a substantially uniform thickness.

  In general, it is very difficult to manufacture the light guide plate 20 by integrating a relatively thick portion and a relatively thin portion while ensuring optical accuracy. In particular, when a resin member is formed by injection molding or the like, sinking is likely to occur due to a difference in thickness, and optical performance may be deteriorated. On the other hand, in this embodiment, it is set as the structure which has several blocks, ie, the 2 part structure which produced 1st block part B1 and 2nd block part B2 separately, and these are joined, and the light-guide plate 20 is produced. Thus, the light guide plate 20 can be manufactured relatively easily and is optically highly accurate.

[E. Production of light guide plate]
Hereinafter, the production of the light guide plate 20 will be described with reference to FIG. First, as shown in FIG. 3A, in manufacturing the light guide plate 20, the first block portion B1 and the second block portion B2 are prepared (block preparation step), and one of the side surfaces of the first block portion B1 is prepared. The joining surface S1 that is a portion and the joining surface S2 that is one of the side surfaces of the second block portion B2 are opposed to each other. Next, as shown in FIG. 3B, an adhesive is supplied between the joining surface S1 and the joining surface S2, the gap is filled with the adhesive, and the adhesive layer CC is formed by curing the adhesive. Then, the first block part B1 and the second block part B2 are joined (block joining step). That is, the joint portion SS of the light guide plate 20 is formed by the joint surfaces S1 and S2 and the adhesive layer CC. Here, the joint surfaces S1 and S2 are both arranged in parallel to the XY plane. That is, the surface is perpendicular to the Z direction, which is the light guide direction in the light guide D2. Thereby, the precision of a 1st block part and a 2nd block part can be raised, and it can suppress that the light which passes joint surface S1, S2 receives to the influence of an angle change.

  As shown in the drawing, the first block portion B1 is a thick block member having a light incident portion D1. On the other hand, the second block portion B2 is a thin plate-like member as a whole having a main portion of the light guide portion D2 and the like. In the present embodiment, a thick block-like first block portion B1 and a thin flat plate-like second block portion B2 are individually manufactured and then joined together to produce an optically highly accurate light guide plate 20. is doing.

  Hereinafter, the process of manufacturing each block part B1, B2 included in the block preparation process will be specifically described. First, the manufacturing process of the first block portion B1 will be described. When the first block portion B1 is manufactured, first, a resin-made main body portion BBa is formed into a block shape by injection molding (injection molding process). That is, the main body portion BBa is formed as a square columnar thick portion TT having the light incident surface IS, the inclined surface RS, the joint surface S1, and the like as side surfaces. In this case, the main body portion BBa is formed by molding only a thick portion of the light guide plate 20 and does not have a thin portion. The occurrence of sink marks can be suppressed. Next, the incident light folded curved surface 21 is formed by performing film formation by aluminum deposition or the like on the slope RS of the molded body portion BBa (folded curved surface forming step). Thereby, the first block part B1 having a part functioning as the light incident part D1 is produced. In this case, since the shape of the main body portion BBa has high optical accuracy, the first block portion B1 has high optical accuracy.

  Next, a manufacturing process of the second block portion B2 will be described. When the second block portion B2 is manufactured, first, the resin-made main body portion BBb is formed into a flat plate shape by injection molding (injection molding step). In this injection molding, the main body portion BBb is molded in a state having total reflection surfaces 22 a and 22 b of the total reflection surface forming portion 22 and inclined surfaces for forming the fine structure of the image extraction portion 23. Here, since the main body portion BBb has a flat plate shape with a substantially constant thickness as a whole, even if it is formed by injection molding, the occurrence of sink marks can be suppressed and the accuracy can be made relatively high. . Therefore, the total reflection surfaces 22a and 22b can have high parallelism. Further, the flatness and the inclination angle of the inclined surface constituting the fine structure of the image extraction unit 23 can be made with high accuracy. Next, a reflective film is formed on the inclined surface to form the reflective surfaces 23a and 23b (see FIG. 2A, etc.) of the image extraction unit 23 (reflective film forming step), and further formed. Further, the image extraction portion 23 is formed by filling the reflective film with a resin having the same refractive index and light transmittance as the main body portion BBb (resin filling step). Thus, the second block portion B2 is produced. In this case, since the shape of the main body portion BBb is high in optical accuracy, the second block portion B2 is optically accurate.

  As described above, in the light guide plate 20 according to the present embodiment, the first block portion B1 and the second block portion B2 are individually manufactured and joined together. Thereby, since the occurrence of sink marks is suppressed in the production of the block portions B1 and B2, the thick portion TT having high optical performance as the light guide plate 20 can be produced relatively easily. At this time, the thick portion TT functions as the light incident portion D1, so that the light guide plate 20 can capture more image light at the light incident portion D1. In addition, the virtual image display device 100 incorporating the light guide plate 20 can be easily manufactured with relatively high accuracy.

[Second Embodiment]
Hereinafter, a second embodiment obtained by modifying the first embodiment will be described with reference to FIG. Since the light guide plate according to the present embodiment has the same structure as the light guide plate 20 shown in FIG. 1 (A) and the like except for the divided portions of the first and second block portions, FIGS. 4 (A) and 4 (B) 3), only elements corresponding to the joining of the block parts B1 and B2 shown in FIGS. 3A and 3B are shown, and each element as a functional part of the light guide plate 20 such as the image extraction unit 23 is shown. The description etc. is omitted.

  As shown in FIG. 4 (A), in the present embodiment, the thick portion is that the first block portion B1 and a part of the second block portion B2 cooperate to form the thick portion TT. This is different from the first embodiment in which TT is formed only by the first block portion B1. More specifically, the first block portion B1 and the second block portion B2 extend the second total reflection surface 22b, which is one of the first and second total reflection surfaces 22a and 22b. The light incident part D1 is divided by an extended surface ES which is a surface. That is, the second block portion B2 has the extended surface ES as the bonding surface S2, and the first block portion B1 has a surface corresponding to the extended surface ES as the bonding surface S1. As shown in FIG. 4 (B), these joining surfaces S1 and S2 are joined via an adhesive layer CC to form a joined portion SS, and as a joined state, a light incident portion D1 or a thick portion. TT is formed. In this case, the second block portion B2 has a difference in thickness on the basis of the width T1 of the total reflection surface forming portion 22 in the X direction that is the distance between the first total reflection surface 22a and the second total reflection surface 22b. It becomes a shape with no gap, and it is easy to process with high accuracy. Moreover, since the first block portion B1 is also relatively thin and has a shape with no difference in thickness, sink marks are unlikely to occur. In this case, the incident light folding surface 21 may be formed after the first block portion B1 and the second block portion B2 are joined. From the viewpoint of the above, the second total reflection surface 22b is a surface located on the protruding side (+ X side) of the light incident part D1, and the first total reflection surface 22b is divided by an extended extension surface ES, so that the first The first block portion B1 is made relatively thin while keeping the shape of the two block portions B2 in a flat plate shape with no difference in thickness.

[Third Embodiment]
Hereinafter, a third embodiment obtained by modifying the second embodiment will be described with reference to FIG. Since the light guide plate according to the present embodiment has the same structure as the light guide plate 20 shown in FIG. 4A and the like except that it has a positioning member, in FIG. 5A and the like, FIG. Only those corresponding to the joining of the block parts B1 and B2 shown in FIG. 6 are shown, and the description etc. is omitted for each element as a functional part of the light guide plate 20 such as the image extraction part 23.

  As shown in FIGS. 5A to 5D, the light guide plate 20 according to this embodiment has a pair of positioning members 25 and 25 at positions adjacent to the joint surface S2 of the block portion B2. More specifically, as shown in FIGS. 5A and 5B, each positioning member 25 extends in parallel to the XY plane of the block portion B1 and abuts on a side surface SK that is not used optically. This is a rectangular parallelepiped protrusion having a contact surface PP for causing the contact. Further, as shown in FIGS. 5C and 5D, the pair of positioning members 25 and 25 are provided at the + Y side end and the −Y side end, respectively, and the joining surface S1 and the joining surface. The positioning is ensured without deviation from S2. Further, as shown in FIG. 5C, the positioning members 25 and 25 are both formed in a region outside the optical path of the entire luminous flux of the image light GLY that is image light viewed in the vertical direction, that is, the Y direction. Thus, the image light is not affected.

[Fourth Embodiment]
Hereinafter, a fourth embodiment obtained by modifying the first embodiment will be described with reference to FIG. Since the light guide plate according to the present embodiment has the same structure as the light guide plate 20 shown in FIG. 1A except for the divided portions of the first and second block portions, in FIG. Only those corresponding to the joining of the block portions B1 and B2 shown in FIG.

  As shown in FIG. 6A, in the present embodiment, the thick portion is that the first block portion B1 and a part of the second block portion B2 cooperate to form the thick portion TT. This is different from the first embodiment in which TT is formed only by the first block portion B1. More specifically, as shown in FIG. 6B, the first block portion B1 and the second block portion B2 are cuts that pass through the boundary between the light incident surface IS and the incident light folding curved surface 21. The thick portion TT is divided by the surface DS. That is, the first block portion B1 and the second block portion B2 have a boundary portion U1 between the incident light folding surface 21 and the light incident surface IS as one end, and the side surface SK and the second block portion B2 that are not used optically. The cut surface DS which is a boundary surface extending with the boundary portion U2 as the other end has joint surfaces S1 and S2. That is, the block portions B1 and B2 in the separated state as shown in FIG. 6A are joined at the joint surfaces S1 and S2 via the adhesive layer CC as shown in FIG. As a result, the thick portion TT is formed. In this case, the incident light folding curved surface 21 is provided in the first block portion B1, and the light incident surface IS is provided in the second block portion B2. That is, the incident light folding surface 21 and the light incident surface IS are included in one member. Accordingly, the light guide plate 20 has a relatively high optical accuracy in reflecting the light at the incident light folding surface 21 and taking in the light at the light incident surface IS in the light incident portion D1 (see FIG. 3B, etc.). Can be a thing. Moreover, since the thickness of each block part B1, B2 can also be made comparatively uniform, generation | occurrence | production of sink can be suppressed in injection molding.

  FIG. 6C shows a modification of the present embodiment, and the second block portion B2 further has a positioning member 25. In this case, the contact surface PP of the positioning member 25 contacts the side surface SK of the first block portion B1 when the block portions B1 and B2 are joined, so that the joining surface S1 and the joining surface S2 are reliably positioned without being displaced. Can be made.

[Fifth Embodiment]
Hereinafter, a fourth embodiment obtained by modifying the first embodiment will be described with reference to FIG. Since the light guide plate according to the present embodiment has the same structure as the light guide plate 20 shown in FIG. 1A and the like except for the shape of the first block portion, in FIG. Only the portions corresponding to the joining of the block portions B1 and B2 shown in FIG. 6 are shown, and the description of the elements as functional portions of the light guide plate 20 is omitted.

  As shown by a dotted line in FIG. 7A, the light guide plate 20 according to the present embodiment cuts a part of the first block portion B1 of the light guide plate 20 according to the first embodiment in the first block portion B1. It has a shape. Specifically, as shown in FIG. 7B, the first block portion B1 has a pentagonal prism shape. This is a shape obtained by cutting the triangular prism-shaped surplus portion TP indicated by the dotted line portion in FIG. 7A from the quadrangular prism-shaped first block portion B1 shown in FIG. Since the cut excess portion TP is a portion that is not optically used from the beginning, even if the first block portion B1 has a pentagonal prism shape as shown in FIG. It is possible to function in the same manner as in the case. That is, as shown in FIG. 7C, the first block portion B1 having a pentagonal prism shape and the second block portion B2 having a flat plate shape are joined to each other to function similarly to the light guide plate shown in FIG. The light guide plate 20 is produced.

[Sixth Embodiment]
Hereinafter, the sixth embodiment, which is a modification of the first embodiment, will be described with reference to FIG. Since the light guide plate 220 according to the present embodiment has the same structure as the light guide plate 20 shown in FIG. 1A and the like except for the structure of the image extraction portion, in FIG. Only a schematic diagram enlarging a part of the image extraction unit 223 corresponding to the image extraction unit 23 and the periphery thereof is shown, and illustration and description of the entire structure of the light guide plate and the virtual image display device are omitted.

  Hereinafter, the detailed structure of the image extraction part 223 of the light guide plate 220 according to the present embodiment will be described. As shown in FIGS. 8A and 8B, the image extraction unit 223 includes a large number of image light reflecting surfaces 223a, and each image light reflecting surface 223a is a Z array in which the image light reflecting surfaces 223a are arranged. It extends in the direction extending perpendicularly to the direction, that is, the Y direction. The multiple image light reflecting surfaces 223a are parallel to each other, form the same angle with respect to the first and second total reflection surfaces 22a and 22b, respectively, and transmit a part of the light components of the image light and reflect the rest. It is a partially reflecting surface. The image light reflecting surfaces 223a are connected by a boundary portion 223b that does not have a function as a reflecting surface for extracting image light. As a result, the image light reflecting surfaces 223a are arranged periodically and repeatedly along the Z direction and extend in parallel with each other. Here, one image light reflection surface 223a and one boundary portion 223b adjacent to the image light reflection surface 223a are referred to as a reflection unit 223c.

Hereinafter, among the components of the image light, the image light GLa and the image light GLb that enter the both ends of the image extraction unit 223 will be described. As a premise, the image light including the image lights GLa and GLb is incident on the light guide plate 20 shown in FIGS. 1A and 1B from the light incident surface IS, and as shown in FIG. The first and second total reflection surfaces 22 a and 22 b of the reflection surface forming unit 22 are repeatedly guided by total reflection and reach the image extraction unit 223. First, as shown in FIG. 8A, the image light GLa 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 223 N times (N is a natural number greater than 1), the image light reflecting surface 223a located on the farthest side (+ Z side) of the peripheral portion 223m in the image extracting portion 223 is reached, and the image light reflecting surface 223a 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. Here, the reflection angle α ₋ of the image light GLa is defined as the incident angle with respect to the image light reflection surface 223a.

On the other hand, as shown in FIG. 8B, the image light GLb that is 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 ₊ is the image extraction unit. 223 reached the image light reflecting surface 223a located closest inlet side of the peripheral portion 223 h (-Z side) of the, by the reflection of the image light reflecting surface 223a, the light exit plane at an angle theta ₃ with respect to the optical axis AX OS To the eye EY. The emission angle at this time is an acute angle with respect to the + Z axis. Here, the reflection angle α ₊ of the image light GLb is defined as the incident angle with respect to the image light reflection surface 223a.

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

  Also in the sixth embodiment, as in the case of the first embodiment and the like, the light guide plate 20 can be manufactured relatively easily by adopting the two-part configuration of the first block portion and the second block portion, and High accuracy can be achieved.

[Modification of joint and positioning member]
Hereinafter, a modified example of the joint portion and the positioning portion will be described with reference to FIG. First, the joint portion SS of the light guide plate 20 shown in FIGS. 9A and 9B is configured by the first block portion B1 and the second block portion B2 having a fitting structure. That is, the first block portion B1 has a concave portion P1 for fitting, and the second block portion B2 has a convex portion P2 for fitting. B1 and the second block portion B2 are joined. Further, as a modification, as shown in FIGS. 9C and 9D, the first and second block portions B1 and B2 have a corresponding uneven shape Q1 in which a concave portion and a convex portion are combined for fitting. , Q2 may be included. In addition to this, for example, as shown in FIGS. 10A and 10B, the joint SS formed by fitting by unevenness is an intermediate position in the thickness direction of the flat plate portion of the light guide plate 20, that is, the X direction. It is good also as what is formed. In any of the cases shown in FIGS. 9 (A) to 9 (D) and FIGS. 10 (A) and 10 (B), as illustrated in FIGS. 10 (A) and 10 (B) By forming the adhesive layer CC on the SS, the space between the first block portion B1 and the second block portion B2 can be filled without any gap.

  Further, as shown in FIG. 11A and the like, various modified examples of the positioning member can be considered. For example, as shown in FIGS. 11A to 11D, for the pair of positioning members 25a and 25b, the first positioning member 25a is provided in the first block portion B1, and the first positioning member 25b is provided in the second block portion. It is good also as what is provided in B2. In this case, the contact surface IAa of the first positioning member 25a and the contact surface IAb of the second positioning member 25b are non-adhesive surfaces, and as shown in FIGS. 11 (A) and 11 (B), By making the IAb slightly protrude from the bonding surface S2 to the first block portion B1 side, as shown in FIGS. 11 (C) and 11 (D), the protruding portion is the adhesive layer CC at the time of bonding. Thickness T2. That is, by defining the protrusion amount of the contact surface IAb, the thickness T2 in the light guide direction (Z direction) of the adhesive layer CC can be more accurately defined. Further, the light incident surface IS and the first total reflection surface 22a are aligned by the contact surface IAa. As shown in FIG. 11E, in the pair of positioning members 25, 25 provided in the first block portion B1, the contact surfaces IAa, IAb slightly protrude toward the second block portion B2 side from the joint surface S1. The thickness T <b> 2 in the light guide direction (Z direction) of the adhesive layer CC can also be defined by setting it to the state.

[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 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, the see-through type virtual image display device has been described. However, when it is not necessary to observe an external image, the light reflectance of both the first and second reflecting surfaces 23a and 23b is set to approximately 100%. It is possible.

  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, 23,223 ... image extraction unit, 23a ... first reflecting surface, 23b ... second reflecting surface, 23c ... reflecting unit, 25, 25a, 25b ... positioning member, DESCRIPTION OF SYMBOLS 100 ... Virtual image display apparatus, AX ... Optical axis, B1 ... 1st block part (structural part), B2 ... 2nd block part (structural part), BBa, BBb ... Main part, CC ... Adhesion layer (structure) D1 ... light incident part (functional part), D2 ... light guide part (functional part), D3 ... light emitting part (functional part), DS ... cut surface (surface passing through the boundary) ), ES ... extended surface (extended surface), EY ... Eye, GL1, GL2, GL3, GLa, GLb, Gly ... Image light, IS ... Light incident surface, OA ... Optical axis, OS ... Light exit surface, SS ... Joint, T1 ... Width, T2 ... Thickness, TT ... Thick part

Claims (11)

A light guide plate comprising: a light guide; a light incident part that causes image light to enter the light guide; and a light emission part that emits the image light guided by the light guide to the outside.
A first block part constituting at least a part of the light incident part;
A second block part constituting at least a part of the light guide part;
A joining portion for joining the first block portion and the second block portion;
In a state in which the first block portion and the second block portion are joined by the joint portion, the light incident portion, the light guide portion, and the light emission portion include the first block portion and the second block portion. In the light guide plate, at least the first block part forms a thick part relatively thicker than other parts, and the thick part functions as the light incident part. The light guide unit has first and second total reflection surfaces extending opposite to each other, and the image light taken in from the light incident unit is reflected by the first and second total reflection surfaces. Guiding,
The light emitting unit includes a plurality of reflection units arranged in a predetermined arrangement direction, and allows the image light incident through the light guide unit to be extracted to the outside by bending an optical path in the plurality of reflection units. The light guide plate according to claim 1, further comprising an image extraction unit.   Each of the reflecting units constituting the plurality of reflecting units includes a first reflecting surface and a second reflecting surface that forms a predetermined angle with respect to the first reflecting surface, and is guided by the light guide unit. The reflected image light is reflected by the first reflecting surface, and the image light reflected by the first reflecting surface is further reflected by the second reflecting surface to bend the optical path. The light guide plate described in 1. The thick portion is formed by the first block portion,
In the said junction part, the junction surface of the said 1st block part and the junction surface of the said 2nd block part are perpendicular | vertical with respect to the light guide direction in the said light guide part. The light guide plate according to any one of the above.   The light guide plate according to any one of claims 1 to 3, wherein the thick portion is formed by the first block portion and a part of the second block portion. The light guide has first and second total reflection surfaces extending opposite to each other,
The said 1st block part and the said 2nd block part are dividing the said light-incidence part by the surface which extended one surface among the said 1st and 2nd total reflection surfaces. Light guide plate.   The first block portion and the second block portion include, in the light incident portion, a light incident surface that captures the image light from outside, captures the incident image light, and guides the captured image light. The light guide plate according to claim 5, wherein the thick portion is divided by a surface passing through a boundary with an incident light folding curved surface that is folded back to a part side.   The light guide plate according to any one of claims 1 to 7, further comprising a positioning member for determining a relative positional relationship in joining the first block part and the second block part.   The light guide plate according to claim 8, wherein the positioning member is formed in a region outside the optical path of the image light. The light guide plate according to any one of claims 1 to 9,
An image forming apparatus that forms the image light guided to the light guide plate;
A virtual image display device. A light guide plate manufacturing method comprising: a light guide part; a light incident part that causes image light to enter the light guide part; and a light emission part that emits the image light guided by the light guide part to the outside. ,
A block preparing step of preparing a first block part that constitutes at least a part of the light incident part and a second block part that constitutes at least a part of the light guide part;
A block joining step for joining the first block portion and the second block portion prepared in the block preparation step,
In the state where the first block portion and the second block portion are joined by the block joining step, the light incident portion, the light guide portion, and the light emitting portion are the first block portion and the second block. A method of manufacturing a light guide plate, wherein at least the first block portion is relatively thicker than other portions and forms a thick portion that functions as the light incident portion.

Images