JP5824788B2 - Light guide plate manufacturing method and light guide plate - Google Patents

Description

  The present invention relates to a light guide plate manufacturing method and a light guide plate used in a head mounted display or the like that is used by being mounted on a head.

  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 plurality of partial reflection surfaces arranged to be parallel to each other at a predetermined angle with respect to the main surface of the light guide plate while guiding image light using total reflection. There is known a technique in which image light is reflected and taken out from the light guide plate to cause the image light to reach the retina of the observer (see Patent Document 1). As a method of forming a plurality of partial reflection surfaces of such a light guide plate, there are a method in which a large number of fine prisms are produced, an optical coating to be a partial reflection surface is formed on each of them and bonded after arrangement, A method in which a large number of applied flat plates are stacked and bonded, and then cut at a predetermined angle, or two comb-like transparent substrates are prepared, and after coating one of the transparent substrates, A method of overlapping the slopes of the transparent substrate is considered (see FIGS. 32 to 35). As a similar technique, there is also known a technique in which a reflective layer is formed on a sawtooth portion in order to extract image light (see Patent Document 2).

Special table 2003-536102 gazette JP 2004-157520 A

  In any of the light guide members of Patent Documents 1 and 2, it is necessary that the plurality of reflecting portions for taking out the image light keep the reflection angle and surface state of the reflecting surface well. However, in the manufacturing method of the reflection part shown in the above-mentioned Patent Document 1, the reflection angle tends to be not constant, or a gap tends to be formed between the reflection surface and the transparent substrate, and the reflection state is improved. However, it is not easy to suppress the manufacturing cost if an attempt is made to improve the reflection state. In addition, although the document 2 includes a description that a reflective layer is provided on a sawtooth portion by using a vacuum chamber, there is no detailed disclosure about a manufacturing method.

  Then, an object of this invention is to provide the manufacturing method and light guide plate of a light guide plate which can form the some reflective surface in a light guide plate in a favorable reflective state comparatively easily.

In order to solve the above-described problems, a method of manufacturing a light guide plate according to the present invention includes: (a) one of two surfaces as a part of a resin base material for a light guide plate having two opposing and parallel surfaces; in the groove forming step in which the V-shaped groove having a first flat surface and a second flat surface forming a serrated portion in which a plurality continuous, first of serration formed in (b) groove forming step By forming a reflective material on at least one of the first and second flat surfaces by vapor deposition, the light guided by total reflection inside the light guide plate is extracted to the outside and the observer is allowed to observe the external world image. a reflecting surface forming step of forming a reflecting surface, and the other surface of the by coating a resin material (c) a resin substrate and the same refractive index, filling the reflecting surface formed by the reflecting surface-forming step, second surface Opposite and parallel surfaces are formed, the other surface is parallel to one surface and the other surface Having a reflecting surface embedded steps that form a light guide portion and the image extraction portion and is integrated structure that light guide by total internal reflection light incident on the inside by the either side of the plane . Here, the vapor deposition method includes not only PVD (physical vapor deposition method) but also CVD (chemical vapor deposition method). In addition, the resins having the same refractive index include not only those having the same refractive index but also those having substantially the same refractive index such that the refractive index difference is within 0.01.

According to the manufacturing method of the light guide plate, and two parallel sides facing, and on one surface formed serrated grooves of the two surfaces, previously prepared resin substrate having a reflective surface formed In the process, a reflective material is formed at an appropriate position of the sawtooth groove to form a reflective surface, so that a reflective surface having a desired light reflectance is formed so as to stably adhere to the groove surface of the resin base material. It is possible to efficiently extract image light with less disturbance to the outside of the light guide plate and to allow the observer to observe the external world. In the reflective surface embedding step, the reflective surface is embedded with a coating resin material having the same refractive index as that of the resin base material, and a parallel surface is formed opposite to the other of the two surfaces. The light guide unit that guides light by totally reflecting the light incident on the surface and one of the surfaces parallel to the one surface and the other surface are integrated with the image extraction unit. by Rukoto form a structure, the reflective surface can suitably protected, it can smooth the unevenness caused by the groove. Thus, relatively easily a plurality of reflecting surfaces of the light guide plate in can be formed with good reflective state, Ru can to what can be observed without distorting the external image as see-through type.

  In a specific aspect of the present invention, in the reflective surface forming step, the reflective material is obliquely vapor-deposited at a predetermined angle, whereby the first reflective surface portion corresponding to the first flat surface as the reflective surface, and the second And a second reflecting surface portion corresponding to the flat surface. In this case, the produced light guide plate can extract image light by two-stage reflection by the first reflection surface portion and the second reflection surface portion.

  In still another aspect of the present invention, in the reflective surface forming step, the first reflective surface portion and the second reflective surface portion are formed with different film thicknesses. In this case, the light reflectance can be made different between the first reflecting surface portion and the second reflecting surface portion in accordance with the use of the light guide plate.

  In still another aspect of the present invention, the groove forming step includes a cutting step for cutting out the first and second flat surfaces from the resin base material. In this case, in the cutting process, the inclination angle of the first flat surface and the inclination angle of the second flat surface can be adjusted, and the surface state of each surface can be made desired.

  In still another aspect of the present invention, in the groove forming step, a sawtooth portion is formed on the surface of the resin base material by a pressing die. In this case, the first and second flat surfaces in a desired state can be produced relatively easily and quickly by pressing the mold that enables batch processing.

  In still another aspect of the present invention, in the groove forming step, a translucent resin member including a sawtooth portion is formed by an injection mold. In this case, the first and second flat surfaces in a desired state can be produced relatively easily and quickly by injection molding that enables batch molding.

  In yet another aspect of the present invention, a pressing mold or an injection mold for forming a sawtooth portion is formed by anisotropic etching of a crystal material. In this case, the mold surface of the pressing mold or the injection mold for forming the serrated portion is relatively simply made, the angle formed by the first flat surface and the second flat surface is made accurate, and the first surface is formed. And it can set to the shape which can improve the flatness of a 2nd flat surface.

  In yet another aspect of the present invention, a pressing mold or an injection mold for forming a serrated portion has a mold surface obtained by processing single crystal silicon. In this case, a precise mold can be easily produced by application of semiconductor technology, and the angle formed by the first flat surface and the second flat surface can be optimized.

  In still another aspect of the present invention, the resin material is any one of an ultraviolet curable resin, a thermosetting resin, and a thermopolymerizable resin. In this case, in the reflection surface embedding step, the resin material with the reflection surface embedded can be reliably cured by ultraviolet irradiation or heat treatment. In addition, the resin material can be made relatively easily with a relatively high refractive index and good optical properties. Further, by flattening with a transparent resin material, a see-through light guide plate can be easily produced.

  In still another aspect of the present invention, an angle formed between the first flat surface and the second flat surface is 54.7 °. In this case, the luminance unevenness of the image light extracted as virtual image light from the light guide plate can be minimized.

  In still another aspect of the present invention, a method for manufacturing a light guide plate includes image light in a structure formed of a resin base material, a reflective surface, and a resin material formed in a reflective surface embedding step. It further has a light incident part forming step of forming a light incident part for capturing. Thereby, the light incident part of a light-guide plate can be formed additionally.

  In order to solve the above problems, a light guide plate according to the present invention includes: (a) a resin base material having a sawtooth portion in which a plurality of V-shaped grooves having a first flat surface and a second flat surface are continuous; (B) a reflecting portion having a first reflecting surface portion and a second reflecting surface portion corresponding to the first flat surface and the second flat surface of the serrated portion, and (c) resin And a protective layer that is made of a resin material having the same refractive index as that of the substrate and protects the resin substrate by sandwiching the reflection portion.

  According to the light guide plate, the reflecting surface is supported by the resin base material and the protective layer so as to sandwich the reflecting portion while supporting the reflecting portion including the plurality of reflecting units formed of the pair of reflecting surface portions by the resin base material. Can be protected properly. That is, image light with less disturbance can be efficiently extracted to the outside of the light guide plate by the reflecting portion having a plurality of reflecting units in a good reflecting state.

(A) is sectional drawing which shows a virtual image display apparatus, (B) and (C) are the front views and top views of a light-guide plate. (A)-(C) are typical figures for demonstrating the structure of an image extraction part, and the optical path of the image light in an image extraction part. (A) is a figure which shows the confirmation position of the brightness | luminance state of a reproduced image, (B)-(F) shows the relationship between the brightness | luminance state in a confirmation position, and the angle which the 1st and 2nd reflective surface makes. It is a graph to show. It is a flowchart for demonstrating the preparation process of a light-guide plate. (A) is a conceptual diagram for demonstrating a groove | channel formation process among the manufacturing processes of the light-guide plate which concerns on 1st Embodiment, (B) is a conceptual diagram of a reflective surface formation process, (C) Is a conceptual diagram of a coating process, (D) is a conceptual diagram of a pressurizing process and an ultraviolet light irradiation process, (E) is a conceptual diagram of a mold release process, and (F) is a light incident. It is a conceptual diagram of a part formation process. It is an enlarged view for demonstrating the film-forming state of the 1st and 2nd reflective surface. (A) is a conceptual diagram for demonstrating a mounting process and an arrangement | positioning process among the manufacturing processes of the light-guide plate which concerns on 2nd Embodiment, (B) is a conceptual diagram of a pressing process, (C) These are the conceptual diagrams after a groove | channel formation process, (D) is a figure for demonstrating a pressing die. It is a conceptual diagram for demonstrating the manufacturing process of the light-guide plate which concerns on 3rd Embodiment.

[First Embodiment]
Hereinafter, as a premise for explaining the manufacturing method of the light guide plate according to the first embodiment of the present invention, a light guide plate and a virtual image display device incorporating the light guide plate will be described.

[A. Structure of light guide plate and virtual image display device]
A virtual image display device 100 shown in FIG. 1A is applied to a head-on 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. In the virtual image display device 100, the image forming device 10 and the light guide plate 20 are normally provided one by one corresponding to the right eye and the left eye of the observer, but the right eye and the left eye are symmetrical. Therefore, only the right eye is shown here, and the illustration for the left eye is omitted. The virtual image display device 100 as a whole has, for example, an appearance (not shown) like general glasses.

  The image forming apparatus 10 includes a liquid crystal device 11 that is an image display element, and a collimating lens 12 for forming a light beam. The liquid crystal device 11 spatially modulates illumination light from a light source (not shown) to form image light to be a display target such as a moving image. The collimating lens 12 converts the image light emitted from each point on the liquid crystal device 11 into a light beam in a parallel state. The lens material of the collimating lens 12 can be either glass or plastic.

  As shown in FIGS. 1 (A) to 1 (C), the light guide plate 20 includes a light guide plate main body 20a, an incident light bending portion 21, and an image extraction portion 23. The light guide plate 20 emits the image light formed by the image forming apparatus 10 as virtual image light toward the observer's eye EY and recognizes it as an image.

  The overall appearance of the light guide plate 20 is formed by a light guide plate body 20a which is a flat plate extending parallel to the YZ plane in the drawing. In addition, the light guide plate 20 has an image extraction portion 23 composed of a large number of micromirrors embedded in the light guide plate main body portion 20a at one end in the longitudinal direction, and extends the light guide plate main body portion 20a at the other end in the longitudinal direction. It has the structure which has the incident light bending part 21 provided so that it may do.

  The light guide plate main body 20a is a light incident portion that is formed of a light-transmitting resin material or the like and takes in image light from the image forming apparatus 10 on a front side plane that is parallel to the YZ plane and faces the image forming apparatus 10. It has a certain light incident surface IS and a light emitting surface OS which is a light emitting portion for emitting image light toward the observer's eye EY. The light guide plate main body 20a has a rectangular slope RS which is provided on the back side of the light incident surface IS and is inclined with respect to the light incident surface IS, and the mirror layer 21a is coated on the slope RS so as to cover it. Is formed. Here, the mirror layer 21a functions as the incident light bending portion 21 by cooperating with the slope RS. Further, in the light guide plate main body 20a, an image extraction portion 23 having a fine structure is formed along a plane on the back side of the light exit surface OS.

  The incident light bending portion 21 disposed opposite to the light incident surface IS of the light guide plate main body portion 20a is formed by forming a film such as aluminum vapor deposition on the inclined surface RS of the light guide plate main body portion 20a. It functions as a reflection surface for reflecting light and bending the optical path in a predetermined direction close to a substantially orthogonal direction. That is, the incident light bending portion 21 bends the image light incident from the light incident surface IS and traveling in the −X direction as a whole so as to be directed in the + Z direction as a whole, thereby allowing the image light to enter the light guide plate main body portion 20a. Make sure to join.

  Further, the light guide plate main body 20 a receives the image light incident on the inside through the incident light bending portion 21 from the entrance-side incident light bending portion 21 to the back-side image extraction portion 23 to the image extraction portion 23. It has a light guide 22 for guiding.

  The light guide 22 is a main surface of the flat light guide plate main body 20a and is two planes facing each other and extending in parallel to the YZ plane, and totally reflects the image light bent by the incident light bending portion 21, respectively. The first total reflection surface 22a and the second total reflection surface 22b are provided. Here, it is assumed that the first total reflection surface 22 a is on the back side far from the image forming apparatus 10 and the second total reflection surface 22 b is on the front side close to the image forming apparatus 10. In this case, the second total reflection surface 22b is a common surface portion with the light incident surface IS and the light exit surface OS. The image light reflected by the incident bent portion 21 first enters the second total reflection surface 22b and is totally reflected. Next, the image light enters the first total reflection surface 22a 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.

  The image extraction unit 23 disposed to face the light exit surface OS of the light guide plate main body 20a is arranged along the extended plane of the first total reflection surface 22a on the back side (+ Z side) of the light guide unit 22. It is formed close to the extension plane. The image extraction unit 23 reflects the image light incident through the first and second total reflection surfaces 22a and 22b of the light guide unit 22 at a predetermined angle and bends it toward the light exit surface OS. Here, it is assumed that the image light first incident on the image extraction unit 23 is an extraction target as virtual image light. The detailed structure of the image extraction unit 23 will be described later with reference to FIG.

  The light guide plate body 20a has a termination surface ES as a side surface that defines the + Z side end surface of the outer shape of the light guide plate 20. The light guide plate body 20a has an upper end surface TP and a lower end surface BP as an upper surface and a bottom surface that define an end surface on the ± Y side.

  In addition, the refractive index n of the transparent resin material used for the light guide plate body 20a is 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.

  Since the light guide plate 20 has the above-described structure, the image light emitted from the image forming apparatus 10 and incident on the light guide plate 20 from the light incident surface IS is uniformly reflected by the incident light bending portion 21 and bent. The first and second total reflection surfaces 22a and 22b of the light guide unit 22 are repeatedly totally reflected and proceed in a state of having a certain spread substantially along the optical axis OA. By being bent at an angle, it can be taken out and finally emitted from the light exit surface OS. The image light emitted from the light exit surface OS enters the observer's eye EY as virtual image light. By forming the virtual image light on the retina of the observer, the observer can recognize image light such as video light by the virtual image.

[B. (Optical path of image light)
Hereinafter, the optical path of the image light will be described in detail. As shown in FIG. 1A, a component emitted from the central portion of the emission surface 11a indicated by a dotted line in the image light emitted from the emission surface 11a of the liquid crystal device 11 is referred to as image light GL1. The component emitted from the right side (-Z side) of the drawing surface 11a in the periphery of the emission surface 11a indicated by the middle one-dot chain line is the image light GL2, and the left side (+ Z side) of the periphery of the emission surface 11a indicated by the two-dot chain line in the drawing. Let the component emitted from the image light GL3.

The main components of the image lights GL1, GL2, and GL3 that have passed through the collimating lens 12 are all incident at different angles on the first and second total reflection surfaces 22a and 22b after entering from the light incident surface IS of the light guide plate 20, respectively. Repeat reflection. Specifically, among the image lights GL1, GL2, and GL3, the image light GL1 emitted from the central portion of the emission surface 11a is reflected by the incident light bending portion 21 as a parallel light flux, and then the standard reflection angle θ _0. Then, the light is incident on the second total reflection surface 22b of the light guide 22 and is totally reflected. Thereafter, the image light GL1 is, while maintaining the standard reflection angle theta _0, first and second total reflection surface 22a, repeating total reflection at 22b. The image light GL1 is totally reflected N times (N is a natural number) at the first and second total reflection surfaces 22a and 22b, and enters the central portion 23k of the image extraction unit 23. The image light GL1 is reflected at a predetermined angle at the central portion 23k, and is emitted as a parallel light flux in the optical axis AX direction perpendicular to the YZ plane including the light emission surface OS from the light emission surface OS. The image light GL2 emitted from one end side (−Z side) of the emission surface 11a is reflected by the incident light bending portion 21 as a parallel light flux, and then the second entire light of the light guide portion 22 at the maximum reflection angle θ _+. The light enters the reflection surface 22b and is totally reflected. The image light GL2 is totally reflected NM times (M is a natural number) on the first and second total reflection surfaces 22a and 22b, and is predetermined in the peripheral portion 23h on the innermost side (+ Z side) of the image extraction portion 23. And is emitted from the light exit surface OS as a parallel light beam in a predetermined angle direction. The exit angle at this time is such that it is returned to the incident light bending portion 21 side, and becomes an obtuse angle with respect to the + Z axis. The image light GL3 emitted from the other end side (+ Z side) of the emission surface 11a is reflected by the incident light bending portion 21 as a parallel light beam, and then the second entire light of the light guide portion 22 with a minimum reflection angle θ _−. The light enters the reflection surface 22b and is totally reflected. The image light GL3 is totally reflected N + M times at the first and second total reflection surfaces 22a and 22b, and is reflected at a predetermined angle by the peripheral portion 23m on the most entrance side (−Z side) of the image extraction portion 23, The light exits from the light exit surface OS in a predetermined angular direction as a parallel light flux. The exit angle at this time is such that it is away from the incident light bending portion 21 side, and is an acute angle with respect to the + Z axis. 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, this hardly causes luminance unevenness, and does not feel the influence of image unevenness or the like on visual recognition. Further, the image light GL1, GL2, and GL3 are described on behalf of a part of the entire light beam of the image light. However, light beam components constituting other image light are guided in the same manner as the image light GL1 and the like. Since these are emitted from the light exit surface OS, illustration and description thereof are omitted. Note that the image lights GL2 and GL3 are slightly refracted when passing through the light exit surface OS.

Here, as an example of the value of the refractive index n of the transparent resin material used for the incident light bending part 21 and the light guide part 22, when n = 1.5, the value of the critical angle θ _c is θ _c ≈41. .8 ° and n = 1.6, the value of the critical angle θ _c is θ _c ≈38.7 °. Each image light GL1, GL2, the reflection angle theta ₀ of _GL3, θ _+, θ _- minimum at a reflection angle theta of _- a by a value larger than the critical angle theta _c, the light guide portion for the required image light 22 to satisfy the total reflection condition.

[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 in detail with reference to FIG.

  First, the structure of the image extraction unit 23 will be described. The image extraction unit 23 includes a large number of linear reflection units 23c arranged in a stripe shape. That is, as shown in FIGS. 2 (A) to 2 (C), the image extraction unit 23 includes a plurality of elongated reflection units 23c extending in the Y direction in the direction in which the light guide unit 22 extends, that is, the Z direction, at a predetermined pitch PT. Is made up of. Each reflection unit 23c has a first reflection surface 23a disposed on the back side, that is, on the downstream side of the optical path, and a second reflection surface 23b disposed on the entrance side, that is, on the upstream side of the optical path. Each reflection unit 23c is formed in a V shape or a wedge shape in the XZ sectional view by the adjacent first and second reflection surfaces 23a and 23b. More specifically, the first and second reflection surfaces 23a and 23b are parallel to the first total reflection surface 22a shown in FIG. 1A and the like and perpendicular to the Z direction in which the reflection units 23c are arranged. The direction extending in a straight line, that is, the Y direction extends in a linear shape. Further, the first and second reflection surfaces 23a and 23b are inclined at different angles (that is, different angles with respect to the YZ plane) with respect to the first total reflection surface 22a with the longitudinal direction as an axis. Yes. As a result, the first reflecting surfaces 23a are periodically and repeatedly arranged and extend in parallel with each other, and the second reflecting surfaces 23b are also periodically and repeatedly arranged and extend in parallel with each other. In the specific example shown in FIG. 2A and the like, each first reflection surface 23a is assumed to extend along a direction (X direction) substantially perpendicular to the first total reflection surface 22a. Each second reflecting surface 23b extends in a direction that forms a predetermined angle (relative angle) α with respect to the corresponding first reflecting surface 23a. Here, it is assumed that the relative angle α is, for example, 54.7 °.

  In the specific example shown in FIG. 2A and the like, the first reflecting surface 23a is assumed to be substantially perpendicular to the first total reflecting surface 22a, but the direction of the first reflecting surface 23a is guided. Any tilt angle within a range of, for example, 80 ° to 100 ° clockwise with respect to the −Z direction with respect to the first total reflection surface 22a is appropriately adjusted according to the specifications of the optical plate 20. It can be made. In addition, the direction of the second reflection surface 23b is appropriately adjusted based on the inclination state of the first total reflection surface 22a according to the specification of the light guide plate 20, and with respect to the first total reflection surface 22a. Thus, any tilt angle can be formed in the range of, for example, 30 ° to 40 ° clockwise with respect to the −Z direction. As a result, the second reflection surface 23b has a relative angle of about 40 ° to 70 ° with respect to the first total reflection surface 22a.

  Hereinafter, the bending of the optical path of the image light by the image extraction unit 23 will be described in detail. 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.

First, as shown in FIG. 2A and FIG. 2B, which is an enlarged view thereof, the image light GL2 guided at the reflection angle θ ₊ having the largest total reflection angle among the image light is transmitted to the image extraction unit 23. Among them, the light is incident on one reflection unit 23c disposed in the peripheral portion 23h on the + Z side farthest from the light incident surface IS (see FIG. 1A). As shown in FIG. 2B, in the reflection unit 23c, the image light GL2 is first reflected by the first reflection surface 23a on the back side, that is, the + Z side, and then the first light surface on the entrance side, that is, the −Z side. Reflected by the second reflecting surface 23b. The image light GL2 that has passed through the reflection unit 23c is emitted from the light exit surface OS shown in FIG. 1A or the like without passing through the other reflection unit 23c. That is, the image light GL <b> 2 is bent at a desired angle and extracted to the observer side by only one pass through the image extraction unit 23.

Further, as shown in FIG. 2A and FIG. 2C, which is an enlarged view thereof, the image light GL3 guided at the reflection angle θ ₋ having the smallest total reflection angle is incident on the image extraction unit 23. The light is incident on one reflection unit 23c disposed in the peripheral portion 23m on the −Z side closest to the surface IS (see FIG. 1A). As shown in FIG. 2 (C), in the reflection unit 23c, the image light GL3 is first, as in the case of the image light GL2 of FIG. Then, the light is reflected by the second reflecting surface 23b on the entrance side, that is, the -Z side. The image light GL3 that has passed through the reflection unit 23c is bent to a desired angle and taken out to the viewer side by passing through the image extraction unit 23 only once without passing through the other reflection unit 23c.

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 FIGS. 2B and 2C, when each image light is incident. The bending angle β, which is the angle formed by the direction of and the direction of injection, is β = 2 (R−α) (R: right angle). That is, the bending angle β is constant regardless of the incident angle with respect to the image extraction unit 23, that is, the values of the reflection angles θ ₀ , θ ₊ , θ _{− and the} like that are the total reflection angles of the respective image lights. Accordingly, as described above, a component having a relatively large total reflection angle in the image light is incident on the + Z side peripheral portion 23h side of the image extracting unit 23, and a component having a relatively small total reflection angle is input to the image extracting unit. Even when the light beam is incident on the peripheral portion 23m side on the −Z side of the image 23, the image light can be efficiently extracted in an angle state so as to collect the image light as a whole on the eye EY of the observer. Since the image light is extracted in such an angular relationship, the light guide plate 20 can pass the image light only once without passing the image light a plurality of times in the image extraction unit 23, and the virtual image can be obtained with little loss. It can be extracted as light.

In addition, in the optical design such as the shape and refractive index of the light guide 22 and the shape of the reflection unit 23c constituting the image extraction unit 23, by appropriately adjusting the angle etc. through which the image light GL2, GL3, etc. are guided, The image light emitted from the light exit surface OS can be incident on the observer's eye EY as virtual image light with the overall symmetry maintained around the basic image light GL1, that is, the optical axis AX. In other words, the angle gamma ₂ with respect to the X direction or the optical axis AX of the image light GL2 at one end, and the angle gamma ₃ with respect to the X direction or the optical axis AX of the image light GL3 the other end, in a substantially equal opposite magnitude Yes. Note that the angles γ ₂ and γ ₃ of the image light GL2 and GL3 are relatively perpendicular to the light exit surface OS or the second total reflection surface 22b, and are sufficiently transmitted through the light exit surface OS. Pass at a rate.

  Here, the light reflectance of the first reflecting surface 23a is higher than the light reflectance of the second reflecting surface 23b. More specifically, the light reflectance of the second reflecting surface 23b is 50% or more, and the light reflectance of the first reflecting surface 23a is approximately 100%. Thereby, the reflection efficiency of the image light at the first and second reflection surfaces 23a and 23b described above can be made relatively high. As described above, the virtual image display device 100 is of a see-through type that allows an observer to observe an external image. In this case, in general, light reflection of each reflective surface is requested in order to ensure observation of the external image. There is an upper limit on the rate. That is, for example, in the above description, the light reflectance of the second reflecting surface 23b is set to 50% or more, but this light reflectance is provided with a specification upper limit of, for example, 70%. On the other hand, when the first reflection surface 23a is perpendicular or substantially perpendicular to the first total reflection surface 22a as shown in FIG. 2A and the like, the observation of the external image is not affected. Therefore, the light reflectance can be set to approximately 100%. Accordingly, in this case, the light reflectance at the first reflecting surface 23a is increased to about 100%, thereby ensuring the transmission at the second reflecting surface 23b, while allowing observation of the external field image. The reflection efficiency of the reflection unit 23c as a whole combining the first and second reflection surfaces 23a and 23b can be increased.

  Further, as already described, the first reflecting surface 23a or the second reflecting surface 23b constituting the group of reflecting units 23c have a constant pitch and are parallel to each other. Thereby, the image light which is the virtual image light incident on the eye EY of the observer can be made uniform, and the deterioration of the quality of the observed image can be suppressed.

  Moreover, the predetermined angle (relative angle) α formed by the first and second reflecting surfaces 23a and 23b of the reflecting unit 23c shown in FIG. 2A and the like is α = 54.7 ° in a specific example. FIGS. 3A to 3F show the relationship between the relative angle formed by the first and second reflecting surfaces 23a and 23b and the luminance distribution of the image light. Here, FIGS. 3B to 3F show the relative angle α in the range of 53 ° to 57 ° with respect to the BB ′ cross section (luminance cross section) in the reproduced image shown in FIG. It is a graph which shows the state of the brightness | luminance at the time of changing suitably by. As can be seen from FIGS. 3B to 3F, when the value of the relative angle α shown in FIG. 3D is α = 54.7 °, the BB ′ cross section in FIG. In FIG. 3B and the like, it can be seen that the luminance unevenness is smaller as it is closer to α = 54.7 °.

[D. Method for manufacturing light guide plate]
Hereinafter, with reference to FIG.4 and FIG.5 (A) -5 (F), the manufacturing method of the light-guide plate which concerns on this embodiment is demonstrated.

  First, as the first step of the light guide plate manufacturing procedure shown in the flowchart of FIG. 4, as shown in FIG. 5A, a large number of first and second reflecting surfaces 23 a and 23 b (FIG. 2) of the image extraction unit 23. (See (A), etc.) Groove processing is performed to directly form the groove DTa provided with the first and second flat surfaces 123a, 123b on the resin base material 50 (groove forming step of step S1 in FIG. 4). . Specifically, as shown in the drawing, the upper surface 50a of the translucent and flat resin base material 50 is cut by a cutting tool DB such as a diamond tool having a wedge-shaped chip shape and arranged in a stripe shape. A large number of grooves DTa are formed on the resin base material 50 (cutting process). Here, the cutting tool DB is set so that the tip angle thereof is equal to the relative angle α (α = 54.7 °) formed by the reflecting surfaces 23a and 23b, and each groove DTa constituting the sawtooth portion DT. Can be precisely processed to the relative angle α. As a result, a sawtooth portion DT in which a large number of V-shaped grooves DTa constituted by the first flat surface 123a and the second flat surface 123b that are adjacent to each other are arranged at regular intervals is cut out.

  Next, as shown in FIG. 5B, on the sawtooth portion DT of the resin base material 50, a reflective film MB as a reflective portion for forming the first and second reflective surfaces 23a and 23b is formed. A film is formed by aluminum vapor deposition (reflection surface forming step in step S2 in FIG. 4). In this step, aluminum vapor deposition is oblique vapor deposition in which aluminum as a reflective material is injected from the direction of arrow AW in the drawing. That is, the direction of the arrow AW, that is, the incident angle of the aluminum particles from the vapor deposition source is appropriately adjusted. Thereby, the first flat surface 123a and the second flat surface 123b have different inclination angles with respect to the incident angle of the aluminum particles, and accordingly, the first flat surface 123a and the second flat surface 123b are in accordance with the inclination angle. The amount of vapor deposition on the flat surface 123b changes, and the thickness of the reflective film MB on the first and second flat surfaces 123a and 123b can be made predetermined. As described above, the first and second reflective surfaces 23a and 23b having different thicknesses and reflectivities are alternately formed as the reflective film MB on the first and second flat surfaces 123a and 123b. That is, one reflection unit 23c is formed by cooperation of one V-shaped groove DTa of the sawtooth portion DT and the reflection film MB, and the image extraction portion 23 is formed as a whole by combining the plurality of reflection units 23c. It is formed. In the reflective surface forming step, the first reflective surface 23a and the second reflective surface 23b, which are a pair of reflective surfaces having different reflectivities, can be simultaneously produced by oblique vapor deposition. Further, because of vapor deposition, the reflective film MB can be formed without a gap so as to be in close contact with the surface of the groove DTa.

  Next, as shown in FIG. 5 (C), the ultraviolet curable resin 51 is applied from above the reflective film MB (application step of step S3 in FIG. 4), and further, as shown in FIG. 5 (D), From above, the pressing member PE, which is a flat substrate, is pressed against the resin base material 50 at a predetermined pressure for a predetermined time required for the ultraviolet curable resin 51 to adhere to the surface of the reflective film MB without a gap (FIG. 4). (Pressurization step of step S4). Here, the ultraviolet curable resin 51 is a translucent resin that is cured by ultraviolet rays, and is a resin having the same refractive index as the resin base material 50. The resin having the same refractive index includes not only those having the same refractive index but also those having substantially the same refractive index difference, for example, having a refractive index difference of 0.01 or less. Further, the pressure member PE is formed of a light-transmitting material such as a glass plate, and has been previously coated with a release agent. In the pressurizing step, the reflective film MB is sandwiched between the resin base material 50 and the ultraviolet curable resin 51. Further, as shown in the figure, ultraviolet light UV is irradiated from above the ultraviolet curable resin 51. The ultraviolet light UV passes through the translucent pressure member PE, and is cured by irradiating the ultraviolet curable resin 51 (ultraviolet light irradiation process in step S5 in FIG. 4). That is, the irradiation with the ultraviolet light UV is performed until a predetermined time necessary for completely curing the ultraviolet curable resin 51 elapses. Thereafter, as shown in FIG. 5 (E), the pressure member PE is released from the ultraviolet curable resin 51 (the release step of step S6 in FIG. 4). As described above, the integrated structure 60 is formed in a state in which the reflective film MB is embedded and covered with the protective layer 52 obtained from the ultraviolet curable resin 51 (completion of the reflective surface embedding process). In this case, in the structure 60, the reflective film MB is embedded and protected, so that oxidation, physical defects, and the like can be suppressed. That is, the protective layer 52 has a role of sandwiching and protecting the reflective film MB together with the resin base material 50. The structure 60 described above includes not only the image extraction unit 23 and the vicinity thereof, but also a part to be the light guide unit 22 of the light guide plate body 20a illustrated in FIG. Can do.

  In the structure 60, since the resin base material 50 and the protective layer 52 are made of resin having the same refractive index, effects such as light refraction and reflection hardly occur between them. That is, the structure 60 does not have a refractive effect when external light is transmitted, and does not affect the light guide of image light.

  When the structure 60 includes the light guide part 22 as described above, for example, as shown in a simplified form in FIG. 5F, the light incident part IS and the incident light bent part with respect to the structure 60. The light guide plate 20 can be manufactured by joining members including 21 and the like. Specifically, a triangular prism prism 53 provided with the light incident portion IS and the incident light bending portion 21 is separately prepared, and the prism is made of a resin material having the same refractive index as that of the resin base material 50 of the structure 60. By joining to the structure 60, the light incident part IS or the like is connected to the structure 60 (the light incident part forming step in step S7 in FIG. 4), and the light guide plate 20 can be produced (light guide plate producing step). Completion). Note that the incident light bending portion 21 can be finally completed by forming the mirror layer 21a after the prism is bonded to the structure 60. Furthermore, a resin base material 50 integrally provided with the prism as described above is prepared in advance, and a reflective film MB is formed on one end side of the resin base material 50 by subsequent processing, and the reflective film MB is formed by the protective layer 52. In addition to the embedding, the structure 60 in which the mirror layer 21 a is formed on the other end side of the resin substrate 50, that is, the light guide plate 20 can be obtained.

  In particular, when the light guide plate 20 and the portion of the structure 60 included in the light guide plate 20 are exposed to the outermost side in the virtual image display device 100, the surface of the protective layer 52 of the structure 60 and the other surfaces in the reflection surface embedding step. By forming one surface flattened with the surface of the light guide plate 20 and having the same refractive index, the virtual image display device 100 can be viewed as a see-through type without distorting the external image.

  FIG. 6 is an enlarged view for explaining the state of the reflective film MB formed by the reflective surface forming step shown in FIG. FIG. 6 shows an example of the state of the first and second reflecting surfaces 23a and 23b formed by the reflecting film MB as one of the reflecting units 23c taken out. The illustrated reflective film MB is a metal material layer and has a uniform thickness corresponding to the first reflective surface portion MB1 and the second reflective surface 23b having a uniform thickness corresponding to the first reflective surface 23a. 2 reflective surface portions MB2. Here, the film thickness t1 of the first reflection surface portion MB1 and the film thickness t2 of the second reflection surface portion MB2 are different from each other. Thereby, the 1st and 2nd reflective surfaces 23a and 23b have required light reflectivity, respectively. As described above, the difference in film thickness between the first reflecting surface portion MB1 and the second reflecting surface portion MB2 is caused by the incidence of aluminum particles as a deposition source in the oblique vapor deposition in the reflecting surface forming step. It can be generated by appropriately adjusting the angle, that is, the direction of the arrow AW in FIG. Here, the film thickness t1 of the first reflective surface portion MB1 is thicker than the film thickness t2 of the second reflective surface portion MB2. Thereby, the light reflectance of the first reflecting surface 23a is set higher than the light reflectance of the second reflecting surface 23b. By adjusting the film thicknesses t1 and t2, for example, the light reflectance of the first reflecting surface 23a is set to approximately 100%, and the light reflectance of the second reflecting surface 23b is set to a predetermined value of 50% or more. Can do. Accordingly, the first and second reflecting surfaces 23a and 23b are bent as the pair of reflecting units 23c by reflecting the incident light with a desired light reflectance when the incident light such as the image light GL2 is bent. Can do.

  As described above, according to the method of manufacturing the light guide plate according to the present embodiment, the resin base material 50 having the sawtooth portion DT is prepared in advance, and the groove DTa constituting the sawtooth portion DT is prepared in the reflective surface forming step. Since the first and second reflecting surfaces 23a and 23b are formed by physically depositing the reflecting material at appropriate positions, the desired light reflectance is obtained so as to stably adhere to the groove DTa surface of the resin base material 50. The first and second reflecting surfaces 23 a and 23 b can be formed, and image light with less disturbance can be efficiently extracted outside the light guide plate 20. Further, in the reflective surface embedding step, the reflective film MB can be protected by embedding the reflective film MB in the light guide plate 20 with a protective layer 52 that is a resin material having the same refractive index as that of the resin base material 50, and the groove DTa. The unevenness due to can be smoothed. As described above, the first and second reflecting surfaces 23a and 23b in the light guide plate 20 can be formed in a good reflection state relatively easily. In addition, the number of steps can be relatively small, and the light guide plate 20 can be easily manufactured.

[Second Embodiment]
Hereinafter, a method for manufacturing the light guide plate according to the second embodiment will be described with reference to FIG. The light guide plate manufacturing method according to the present embodiment is a modification of the light guide plate 20 manufacturing method according to the first embodiment shown in FIG. Since this is the same as the case shown in FIGS. 5B to 5F, only the groove forming step will be described, and illustration and description of the subsequent steps will be omitted.

  As shown in FIG. 7A, in the light guide plate manufacturing method according to the present embodiment, first, the first resin base material 150a, which is a transparent resin, has the same refractive index as that of the resin base material 150a and is transparent. The 2nd resin base material 150b which is a photo-sensitive ultraviolet curable resin is mounted (mounting process). Further, the pressing mold PP having the sawtooth mold surface SS is disposed above the second resin substrate 150b (arranging step). Next, as shown in FIG. 7B, the pressing mold PP disposed above is pressed down with a predetermined pressure against the second resin base material 150b, and the mold surface SS is pressed onto the second resin base material 150b. (Mold transfer) is performed (pressing step). Further, in this state, ultraviolet light UV is irradiated from below the second resin base material 150b to cure the second resin base material 150b (ultraviolet light irradiation step). After the second resin base material 150b is cured, the pressing mold PP is released from the second resin base material 150b (release process). Through the above steps, as shown in FIG. 7C, the first resin base material 150a and the second resin base material 150b are configured, and the serrated portion DT is formed on the surface on the second resin base material 150b side. A resin base material 150 having the above is formed (groove forming step).

  A reflective film MB is formed on the serrated portion DT of the resin base 150 formed in the groove forming step in the same manner as shown in FIGS. 5 (B) to 5 (F) of the first embodiment. (Reflecting surface forming step) Further, the reflective film MB, that is, the reflecting surfaces 23a and 23b is filled with the protective layer 52 of the ultraviolet curable resin 51 (reflecting surface embedding step), thereby forming the structure 60 including the image extraction portion 23. As a result, the light guide plate 20 can be manufactured.

  Here, with reference to FIG.7 (D), the pressing type PP in the said pressing process is demonstrated. The pressing type PP is a transfer type obtained by processing single crystal silicon, which is a crystalline material, using existing semiconductor manufacturing technology. As schematically shown in FIG. 7D, the pressing mold PP is configured by arranging a large number of mold parts PPa having the same shape. Each mold part PPa is a flat plate having opposing main surfaces SSa and SSb, and each end surface SSc is cut out at an equal angle with respect to two parallel main surfaces SSa and SSb. The pair of main surfaces SSa and SSb are formed using anisotropic etching such as wet etching, for example, and are parallel surfaces having high flatness. Further, the end surface SSc is also formed by using anisotropic etching such as wet etching, and has a constant angle with respect to the main surface SSb and the like, and has high flatness. The pressing mold PP is formed by aligning the main surface SSa of each mold part PPa and the main surface SSb of the mold part PPa adjacent to the mold part PPa. Accordingly, the mold surface SS of the pressing mold PP has a part of the plurality of main surfaces SSb and end surfaces SSc alternately and periodically arranged. Thereby, the mold surface SS has a fine structure with very high shape accuracy with respect to flatness and inclination angle. In addition, in this case, by utilizing the characteristics of silicon and its anisotropic etching, the edge angle between the two surfaces SSb and SSc constituting the fine structure of the mold surface SS is such that each groove DTa constituting the sawtooth portion DT is formed. It is set equal to the edge angle, that is, the relative angle α (α = 54.7 °) formed by the reflection surfaces 23a and 23b constituting the reflection unit 23c. Thus, by using single crystal silicon, it is possible to ensure the shape accuracy of the fine structure formed on the mold surface SS, and the flatness of the first and second flat surfaces 123a and 123b, which is The flatness of the surfaces of the first and second reflecting surfaces 23a and 23b can be made high. Furthermore, by using single crystal silicon, the value of the edge angle of the mold surface SS formed by anisotropic etching is such that the reflecting surfaces 23a and 23b constituting the reflecting unit 23c described with reference to FIG. It corresponds to α = 54.7 ° which is the optimum value of the angle formed by

Also in the method of manufacturing the light guide plate according to the present embodiment, the reflection state of the first and second reflection surfaces 23a and 23b in the light guide plate 20 can be kept good. In particular, in the case of this embodiment, the time required for the manufacturing process of the structure body 60 and the like can be made relatively short by pressing the mold, and rapid manufacturing is possible. In the case of the present embodiment, the first and second reflecting surfaces 23a and 23b having a predetermined angle can be made relatively simple by using the pressing type PP that utilizes the anisotropic etching characteristics of single crystal silicon. The surface accuracy can be very high. Since the surface accuracy is high in this way, the image light extracted from the manufactured light guide plate 20 is suppressed from blurring and flare.
Note that the pressing type PP is not limited to one formed using single crystal silicon, but can be formed entirely or partially from other crystals, metals, or the like.

[Third Embodiment]
Hereinafter, with reference to FIG. 8, the manufacturing method of the light-guide plate which concerns on 3rd Embodiment is demonstrated. The light guide plate manufacturing method according to the present embodiment is a modification of the light guide plate 20 manufacturing method of the first embodiment shown in FIG. 5A and the like, and includes a reflective surface forming step and a reflective surface embedding step. Since this is the same as the case shown in FIGS. 5B to 5F, only the groove forming step will be described, and illustration and description of the subsequent steps will be omitted. Note that part of FIG. 8 is omitted for simplification.

  As shown in FIG. 8, in the light guide plate manufacturing method according to the present embodiment, first, for example, the sawtooth portion DT of the image extraction portion 23 or the light guide portion 22 of the light guide plate main body 20a (see FIG. 1A, etc.). A base material portion that should become the same is integrally formed as a translucent resin member 120a. For this reason, first and second metal molds MP1 and MP2, which are a set of metal molds for integrally forming the translucent resin member 120a by injection molding, are prepared (a mold preparation step).

  Here, of the set of metal molds MP1 and MP2, the metal mold MP1 has a sawtooth shape for forming the first and second reflection surfaces 23a and 23b of the image extraction portion 23 as a part of the transfer surface. It has a mold surface SS. This mold surface SS has the same shape as the mold surface SS of the pressing mold PP shown in FIG.

  The metal molds MP1 and MP2, which are a pair of injection molds, are heated moderately and matched and clamped (mold space forming step). Thereafter, a resin material to be the translucent resin member 120a is injected into a mold space formed between the pair of metal molds MP1 and MP2 while being softened at a predetermined temperature, and the injected translucent resin is injected into the mold space. Pressurized (injection process). The cured translucent resin member 120a is taken out from between the pair of metal molds MP1 and MP2 by subsequent cooling and mold release (mold release process). On the translucent resin member 120a molded as described above, the sawtooth portion DT is formed by the mold surface SS of the metal mold MP1 (groove forming step). That is, the translucent resin member 120a is equivalent to the resin base material 50 provided with the serrated portion DT as shown in FIG.

  The translucent resin member 120a does not include the entire light guide plate main body 20a of FIG. 1 (A) as long as it includes the serrated portion DT, and may constitute a part of the light guide plate main body 20a. Good. For example, for the prism portion having the inclined surface RS for forming the incident light bending portion 21 in the light guide plate main body portion 20a, a separate triangular prism may be prepared and then attached by bonding or the like.

  In addition, the mold surface SS of the metal mold MP1 is obtained by incorporating a mold formed by anisotropic etching of single crystal silicon in the same manner as the mold surface SS of the pressing mold PP of the second embodiment. By doing so, a desired shape can be obtained.

  In the above description, it is assumed that the translucent resin member 120a is a thermoplastic resin, but the translucent resin member 120a can be formed of a thermosetting resin or a photocuring resin.

  Also in the method of manufacturing the light guide plate according to the present embodiment, the reflection state of the first and second reflection surfaces 23a and 23b in the light guide plate 20 can be kept good. In particular, in the case of the present embodiment, it is possible to quickly produce the light guide plate 20 having the first and second reflecting surfaces 23a and 23b with relatively high accuracy by injection molding. In the case of the present embodiment, not only the sawtooth portion DT, but also the total reflection surfaces 22a and 22b that are flat portions of the light guide portion 22, the inclined surface RS of the entrance, and the like can be easily and integrally formed of a translucent resin. It can be formed as member 120a.

[Others]
Although the present invention has been described with reference to each embodiment, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the spirit of the present invention. The following modifications are possible.

First, the sawtooth portion DT forms the first and second reflecting surfaces 23a and 23b as reflecting surfaces on both of the first and second flat surfaces 123a and 123b constituting the reflecting surface. May be applied only to one of the first and second flat surfaces 123a and 123b. For example, a reflective surface may be formed only on the second flat surface 123b. In this case, since the first flat surface 123a is embedded with the same refractive index material, it does not function as a reflective surface. Therefore, in this case, the reflection surface of the image extraction unit 23 to be formed is only the second reflection surface 23b. That is, the image extraction unit 23 is configured to extract image light using only one type of conventional reflective surface. In addition, the first and second reflecting surfaces 23a and 23b can have the same characteristics by making the thickness of the reflecting film MB constant.
Note that the reflective film MB can be formed not only by the vacuum vapor deposition method but also by various vapor deposition methods such as ion plating, sputtering, and CVD.

  The reflective film MB is not limited to a metal film such as aluminum, but may be a single-layer or multi-layer dielectric film.

  In the above description, an ultraviolet curable resin is used as the resin material as the protective layer for protecting the reflective film MB, but a thermosetting resin or a thermopolymerizable resin can be used instead. In the case of a thermosetting resin, the cured resin is allowed to function as a protective layer of the reflective film MB by curing the resin by heat treatment instead of the treatment with ultraviolet light UV. By using, for example, a thiourethane or episulfide resin as the thermosetting resin or the thermopolymerizable resin, the refractive index can be increased to about n = 1.6 to 1.8.

  In the above description, the pitch PT of the arrangement of the reflection units 23c constituting the image extraction unit 23 is not limited to the case where the pitches are all the same between the first reflection surfaces 23a. Including the case where there is.

  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 organic EL, LED array, organic LED, etc. is also possible. Further, 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 above description, the virtual image display device 100 is configured to provide 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, but the image extraction unit 23 can also be applied to a virtual image display device other than the see-through type. When it is not necessary to observe an external image, the light reflectance of both the first and second reflecting surfaces 23a and 23b can be made approximately 100%.

  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 subjected to mirror coating or the like to reflect substantially all the image light is included. . 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.

  In the above description, in FIG. 1A and the like, the overall appearance of the light guide plate 20 is a flat plate extending in parallel to the YZ plane, but from the light incident surface IS that is a transmission unit for transmitting image light. Except for the area up to the image extraction section 23, it is possible to use a shape that is not flat but has a different thickness or a curved surface.

  In the above description, when the light guide plate 20 and the portion of the structure 60 included in the light guide plate 20 are exposed on the outermost side in the virtual image display device 100, the surface of the protective layer 52 of the structure 60 and the surface of the other light guide plate 20 are used. Although it is assumed that the surface is flattened, for example, when the light guide plate 20 or the like is not exposed to the outermost side as in the case of attaching a cover to the light guide plate 20, it is not necessarily flattened. Even if there are some steps on the surface, it is acceptable.

  In the above, the light incident surface IS is formed so as to be positioned on the left and right sides of the eye on a plane parallel to the YZ plane. However, if the image light can be properly guided into the light guide plate 20, the light incident surface IS The position of the surface IS is not limited to this, and may be provided on, for example, a part of the upper end surface TP or the lower end surface BP that is the upper side or the lower side of the light guide plate 20.

  Although not mentioned above, the upper end surface TP, the lower end surface BP, and the like of the outer peripheral portion that defines the outer shape of the light guide unit 22 can be used as a black paint application surface or a sandblasted surface. Furthermore, you may perform black coating application | coating or sandblasting to locations other than upper end surface TP and lower end surface BP. Conversely, only a part of the upper end surface TP, the lower end surface BP, or the like may be subjected to black coating or sandblasting.

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 20 ... Light guide plate, 20a ... Light guide plate main-body part, 21 ... Incident light bending part, 22 ... Light guide part, 22a, 22b ... Total reflection surface, 23 ... Image extraction part, 23a, 23b ... Reflective surface portion, 23c ... reflective unit, 100 ... virtual image display device, 50, 150 ... resin base material, 51 ... UV curable resin, 123a, 123b ... flat surface, DT ... sawtooth portion, MB ... reflective film, 60 ... Structure: PP ... Pushing type, SS ... Die surface, IS ... Light incident surface, OS ... Light emitting surface, EY ... Eye, PT ... Pitch, RS ... Incoming light reflecting surface, GL1, GL2, GL3 ... Image light

Claims (12)

A V-shaped groove having a first flat surface and a second flat surface on one of the two surfaces as part of a resin base material for a light guide plate having two parallel surfaces facing each other A groove forming step for forming a plurality of serrated portions,
The light guided by being totally reflected inside the light guide plate by depositing a reflective material on at least one of the first and second flat surfaces of the sawtooth portion formed in the groove forming step by vapor deposition. A reflection surface forming step of forming a reflection surface for allowing an observer to observe an external world image,
The coating resin material having the same refractive index as that of the resin base material fills the reflection surface formed in the reflection surface formation step, and forms a parallel surface opposite the other surface of the two surfaces. A light guide unit and an image extraction unit configured to totally reflect and guide light incident on the other surface, the one surface, and any one of the surfaces facing and parallel to the other surface; a reflecting surface embedded process but you form an integral structure,
The manufacturing method of the light-guide plate which has this.   In the reflective surface forming step, the reflective material is obliquely vapor-deposited at a predetermined angle, whereby the first reflective surface portion corresponding to the first flat surface and the second flat surface are used as the reflective surface. The manufacturing method of the light-guide plate of Claim 1 which forms a corresponding 2nd reflective surface part.   The light guide plate manufacturing method according to claim 2, wherein, in the reflection surface forming step, the first reflection surface portion and the second reflection surface portion are formed with different film thicknesses.   The said groove | channel formation process includes the cutting process for cutting out the said 1st and 2nd flat surface from the said resin base material, The manufacturing method of the light-guide plate as described in any one of Claim 1- Claim 3 .   The manufacturing method of the light-guide plate as described in any one of Claim 1- Claim 3 which forms the said serrated part in the surface of the said resin base material with a pressing die in the said groove | channel formation process.   4. The method for manufacturing a light guide plate according to claim 1, wherein, in the groove forming step, the translucent resin member including the serrated portion is formed by an injection mold. 5.   The light guide plate manufacturing method according to any one of claims 5 and 6, wherein the pressing mold or the injection mold for forming the serrated portion is formed by anisotropic etching of a crystal material. Method.   8. The pressing mold or the injection mold for forming the serrated portion has a mold surface obtained by processing single crystal silicon, according to claim 5. Manufacturing method of light guide plate.   The said coating resin material is a manufacturing method of the light-guide plate as described in any one of Claim 1-8 which is either an ultraviolet curable resin, a thermosetting resin, and a thermopolymerizable resin.   The manufacturing method of the light guide plate according to any one of claims 1 to 8, wherein an angle formed by the first flat surface and the second flat surface is 54.7 °.   Light incidence that forms a light incident part for taking image light into the structure formed by the resin base material formed in the reflection surface embedding step, the reflection surface, and the coating resin material The manufacturing method of the light-guide plate as described in any one of Claim 1- Claim 10 which further has a part formation process. A sawtooth portion in which a plurality of V-shaped grooves having two parallel surfaces facing each other and a first flat surface and a second flat surface formed on one of the two surfaces are continuous. Having a resin substrate;
A reflective portion having a first reflective surface portion and a second reflective surface portion corresponding to the first flat surface and the second flat surface of the serrated portion,
Consists of a coating resin material having the same refractive index as that of the resin base material , has a parallel surface facing the other of the two surfaces, and protects by sandwiching the reflective portion together with the resin base material A protective layer to
With
At least one of the first reflection surface portion and the second reflection surface portion is a reflection film for taking out light guided by total reflection inside the light guide plate to the outside and for allowing an observer to observe an external world image. Oh it is,
There is a light guide unit that totally reflects and guides light incident on the other surface and any one of the one surface and the surface parallel to the one surface and the other surface. Light guide plate.

Images