JP2017067890A - Light guide and virtual image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact light guide for a virtual image display device.SOLUTION: A light guide 50 comprises a light guide member 100 with a light incident section 101 for image light to enter and a light exit section 104 for the image light to exit, and an optical member 200 integrally provided with the light guide member. The light guide member has a reflective section 102 which is formed at an angle with the light incident section 101 to guide the image light entering the light incident section 101 to inside the light guide, and an image extraction section 103 which comprises alternately arranged first surfaces that are at an angle with the light exit section 104 and second surfaces parallel to the light exit section 104, and is configured to guide the image light from the first surfaces to the light exit section 104 in order to extract the image light. The optical member has a parallel surface 210 parallel to the light exit section 104, and a sloped section 203 formed at an angle with the parallel surface 210 and disposed to abut the image extraction section 103.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light guide and a virtual image display device using the light guide.

  A virtual image display device using a light guide is known as a device that enlarges a two-dimensional image using a virtual image optical system and displays the enlarged virtual image so that an observer can observe it. In recent years, a head mounted display (hereinafter referred to as “HMD”) is becoming popular as one form of light guide used in such a virtual image display device. The HMD is classified into a see-through transmission type and a non-transmission type. The transmission type HMD is, for example, Google LTD. There is Googleglass (registered trademark) of (USA).

  The transmissive HMD is used in combination with an information terminal or used for providing AR (Augmented Reality) or the like, so that a small HMD having good portability is desired. The non-transparent HMD is desired to have a wide viewing angle that provides an immersive feeling because it is used for watching movies, providing games, and providing VR (Virtual Reality).

  In recent years, even in the transmissive type, it has been required from the user's needs to be thin, small, and have a wide viewing angle. Are known.

  The apparatus of Patent Document 1 employs a system in which a number of light guides coated with a specific reflectance are overlapped, and the reflection and transmission of light rays are distributed according to the incident angle of light rays to extract an image.

  The device of Patent Document 2 uses total reflection to guide image light through a light guide, and on the image extraction side of the light guide, by providing an external light transmission surface parallel to the main surface of the light guide, Is provided with a transmission function that enables observation by overlapping with external light.

  The apparatus of Patent Literature 3 includes a total reflection portion that extends opposite to each other, a plurality of first element surfaces that extend so as to incline, and a plurality of second element surfaces that extend at an obtuse angle with respect to the first element surface. Are combined with light guide plates that are alternately arranged.

  In these methods, a large number of light guides are required to achieve transparency and a wide viewing angle, a flat light guide plate portion is necessary to maintain see-through, and a light guide is required to widen the viewing angle. There is a need to increase the length.

  The main object of the present invention is to realize a compact light guide for a virtual image display device.

  The present invention is a light guide for a virtual image display device that guides image light from an image display element and emits it to display a virtual image, and includes a light incident portion on which the image light is incident and the image light. A light guide member including a light emitting part for emitting the light to the outside, and an optical member provided integrally with the light guide member, wherein the light guide member is inclined with respect to the light incident part. And a reflective portion for guiding the image light incident on the light incident portion into the light guide, and a first surface inclined with respect to the light emitting portion and a second surface parallel to the light emitting portion are alternately arranged. And an image extracting unit that guides and extracts the image light from the first surface to the light emitting unit, and the optical member is inclined parallel to the parallel surface and parallel to the light emitting unit. And an inclined portion disposed close to the image extraction portion. Also a major feature.

  According to the present invention, a light guide for a virtual image display device can be made compact.

It is a top view which shows embodiment of the light guide which concerns on this invention. It is a perspective view of the light guide of FIG. It is a top view of the virtual image display apparatus using a light guide. It is a partial enlarged plan view for demonstrating the light-beam incident part and reflection part in the light guide member of a light guide. It is a partial enlarged plan view for demonstrating the image extraction part in the light guide member of a light guide. It is the top view and partial enlarged plan view for demonstrating the arrangement | positioning state of the interface of the image extraction part of a light guide member, and the inclination part of an optical member. It is the elements on larger scale which explain other embodiment of a light guide member, (a) is a figure which expands and shows an image extraction part, (b) is a figure which expands and shows an image extraction part further. FIG. 8 is a partially enlarged plan view showing an arrangement state of the light guide member and the optical member in FIG. 7, (a) is an enlarged view showing an image take-out portion, and (b) is an enlarged view showing the image take-out portion. is there. It is a schematic diagram showing the example which applied the light guide of embodiment to spectacles type HMD, (a) is a case where a light guide is made into a monocular type, (b) And (c) is a monocular type light guide. And when applied to the left and right eyes, respectively, and applied to one eye. It is a top view for demonstrating Example 1 of the virtual image display apparatus using the light guide of embodiment. It is a top view for demonstrating Example 2 of the virtual image display apparatus using the light guide of embodiment.

  Embodiments to which the present invention is applied will be described below with reference to the drawings. The following embodiments relate to a transmissive light guide and a virtual image display device using the same.

  1 and 2 show a light guide 50 of the present embodiment, and FIG. 3 shows a configuration of a virtual image display device in which the light guide 50 is arranged on the optical path of a virtual image display optical system. In FIG. 3, the optical path of the virtual image display optical system in the virtual image display device is indicated by an arrow, and the eyes of the user of the device, that is, the virtual image observer, are schematically illustrated. Hereinafter, regarding the surface of the light guide 50, the front side (lower side in FIG. 3) viewed from the observer is referred to as a “rear surface”, and the rear side (upper side in FIG. 3) is referred to as a “front surface”.

  The light guide 50 is an element that enters and guides image light from the image display element and emits it for virtual image display. In this embodiment, the light guide member 100 and the optical member 200 are integrally formed. By being provided, the whole has a substantially prismatic shape and an asymmetric trapezoidal shape in plan view.

  The light guide member 100 of the light guide 50 has a role of taking in and guiding image light from the image display element to the outside for displaying a virtual image. For this reason, the light guide member 100 includes a light beam incident portion 101 for entering image light therein, a reflection portion 102 for reflecting the incident image light and guiding it to the inside, and taking out the guided image light to the outside. An image extracting unit 103 and a light emitting unit 104 for emitting the light are provided.

  In order to improve the see-through property, the light guide member 100 has a rear surface on which the light emitting portion 104 is provided and a front surface 105 on the back side (upper side in FIG. 1), which are flat surfaces and are formed in parallel to each other. Yes.

Both the light incident portion 101 and the light emitting portion 104 are provided on the rear surface of the light guide member 100. Therefore, the light incident part 101 and the light emitting part 104 are arranged on the same plane. Thus, by arranging the light incident part 101 and the light emitting part 104 on the same plane, the productivity of the light guide member 100 and the light guide 50 is improved, and the light guide member 100 and the light guide 50 as a whole. A simple configuration can be achieved.

  The image extraction unit 103 of the light guide member 100 has a role of reflecting the image light guided inside toward the light beam emission unit 104, and the light beam emission unit 104 is an image light guided from the image extraction unit 103. Is emitted outside toward the eyes of the virtual image observer.

  On the other hand, the optical member 200 has a tapered outer shape in plan view, and is provided opposite to the image extraction unit 103 of the light guide member 100, so that mainly the light beam transmission unit 104 and the image extraction unit 103 transmit light. Has the role of ensuring the see-through property.

  The optical member 200 is a front surface 210 as a parallel surface parallel to the light emitting portion 104 of the light guide member 100, and an inclined portion that is inclined with respect to the front surface 210 and is opposed to the image extraction unit 103 of the light guide member 100. 203. The inclined part 203 of the optical member 200 is a part that is installed close to the image extraction part 103 of the light guide member 100, and details of the part will be described later.

  Hereinafter, a virtual image display device using the light guide 50 will be described. 3 includes an image display element 10 that outputs image light of a display image, a collimating optical system 300 that collimates and emits image light from the image display element 10, and the light described above. A guide 50 is provided as a virtual image display optical system.

  The image display element 10 is a device that outputs image light of a display image that is a basis of a virtual image displayed through the light guide 50. The image display element 10 is preferably an organic ELD (OLED: Organic Light Emitting Diode) or a liquid crystal display element, but various other display methods can be applied. For example, a DMD (Digital Micromirror Device) can be applied as the image display element 10. Further, as the image display element 10, TFT (Thin Film Transistor) or LCOS (Liquid Crystal On Silicon) can be applied. Further, as the image display element 10, MEMS (Micro Electro Mechanical Systems) can be applied.

  FIG. 3 shows an example in which LCOS or DMD that requires a light source is used as the image display element 10, and a light source LS for illuminating the image display element 10 is added. Various light sources LS can be applied. For example, an LED (Light Emitting Diode), a semiconductor laser (Laser Diode: LD), a discharge lamp, or the like can be used.

  The collimating optical system 300 includes a plurality of optical lenses, diaphragms, and the like, and enlarges the image light output from the image display element 10 and emits it as parallel light.

  According to this virtual image display device, the image light of the image display element 10 illuminated by the light source LS is magnified by the collimating optical system 300 and enters the light guide 50. In other words, the image light magnified by the collimating optical system 300 enters from the light beam incident portion 101 of the light guide member 100 in the light guide 50, is reflected by the reflection portion 102, and is guided into the light guide member 100. The guided image light is reflected by the image extraction unit 103 and emitted as image information from the light emitting unit 104 toward both eyes of the user. The user can visually recognize the virtual image of the image light by looking forward through the light emitting unit 104 and the optical member 200 of the light guide member 100.

  Next, the configuration of the light guide 50 will be described in more detail with reference to FIG.

  The material of the light guide member 100 is preferably a highly transmissive material in view of see-through properties, and is preferably molded from a resin in consideration of the processing of the image extraction unit 103 described later.

  The light incident part 101 and the reflection part 102 of the light guide member 100 enter and reflect the image light expanded by the collimating optical system 300 as a light bundle. Therefore, the light incident part 101 and the reflecting part 102 are formed with a size larger than the size of the light flux.

  As shown in FIG. 4, the reflecting unit 102 is inclined at an angle θ 0 with respect to the light incident unit 101 in order to reflect the image light incident on the light incident unit 101 and guide it to the inside of the light guide 50. Yes. The inclination angle θ0 is an angle that totally reflects the image light incident from the light beam incident portion 101, and is set to an angle of 15 degrees to 75 degrees in order to guide the image light well into the light guide. Is desirable. Furthermore, in consideration of a preferable range of an angle θa formed by a first surface 103a of the image extraction unit 103 and a light emitting unit 104, which will be described later, the inclination angle θ0 is more preferably set in a range from 20 degrees to 30 degrees. .

  In addition, an arbitrary coat can be applied to the reflecting portion 102. In order to guide the image information to the inside of the light guide 50, it is desirable that the reflecting portion 102 is provided with a mirror coating having a high reflectance such as aluminum, silver, or a dielectric coating.

  As shown in FIG. 5, the image extraction unit 103 includes a first surface 103 a having an angle θa with respect to the light emitting unit 104 and a second surface 103 b having an angle θb with respect to the light emitting unit 104. They are arranged alternately and have a substantially staircase shape. In FIG. 5, the reference plane parallel to the light emitting section 104 is represented by a dotted line, and the width of the second surface 103b is represented by w.

  The first surface 103 a of the image extraction unit 103 is a surface that plays a role of guiding the image light incident and guided into the light guide member 100 to the light emitting unit 104 and emitting it from the light emitting unit 104. The plane is inclined with respect to the portion 104. Here, the inclination direction of the first surface 103 a with respect to the light emitting part 104 is opposite to the inclination direction of the reflecting part 102 with respect to the light incident part 101. The value of the angle θa at which the first surface 103a is inclined with respect to the light emitting portion 104 is preferably set in the range of 20 degrees to 30 degrees, although it depends on the refractive index of the material of the light guide member 100. Further, it is more preferable to set the value of the angle θa to be the same as the value of the inclination angle θ0 of the reflecting unit 102 with respect to the light beam incident unit 101 described above. Becomes easier.

  On the other hand, the second surface 103 b is a surface serving as a reflecting surface that guides incident image light into the light guide member 100, and is a plane parallel to the light emitting unit 104. Therefore, the angle θb = 0 °. Further, the second surface 103b also serves as a transmission surface for allowing external light from the front and rear surfaces of the light guide 50 to enter in order to ensure see-through performance.

  When the second surface 103b is tilted with respect to the light emitting section 104, that is, when the angle θb ≠ 0 ° is set, the image light guided in the light guide member 100 has a reflection angle reflected by the second surface 103b. The angle of reflection reflected by the light emitting section 104 changes without matching. In this case, the incident angle θin defined by the angle formed by the light beam incident from the light beam incident unit 101 and the normal line of the light beam incident unit 101, the light beam emitted from the light beam emitting unit 104, and the normal line of the light beam emitting unit 104 The exit angle θout defined by the angle formed by and is not the same angle. Further, when the image light is emitted to the outside of the light guide 50 through the first surface 103a and the light emitting unit 104, it is emitted in a different direction, which is not a virtual image. Therefore, in the present embodiment, the angle θb = 0 °, and the second surface 103 b is formed in parallel to the light emitting portion 104.

The value of the width w of the second surface 103b of the image extraction unit 103 in the light guide member 100 is
0.5 [mm] <w <3.0 [mm]
Is set so as to satisfy the following conditions. Here, the width w is the length of the second surface 103b in the direction along the longitudinal direction of the light guide member 100, that is, the direction along the traveling direction of the incident image light.

  Hereinafter, the setting condition of the width w of the second surface 103b will be described in detail.

The width of the field of view that can be confirmed as a virtual image is referred to as “eye box”, and the distance from the light emitting unit 104 that can confirm the virtual image to the eyeball is referred to as “eye relief”. The diameter of the eye box is φ, the eye relief is L, the thickness (thickness) of the light guide is t _l , and the number of surfaces parallel to the light emitting unit 104 of the image extraction unit 103, that is, the number of the second surfaces 103b is n. Then, the width w of the second surface 103b is expressed by the following equation.

  Here, the wider the eyebox width, the wider the visible range, so it is usually desirable that the eyebox diameter φ is larger. On the other hand, when the eyebox diameter φ is increased, the thickness of the light guide increases, and the design difficulty of the light guide tends to increase.

  In general, the diameter of the pupil of the eye is about 5 mm. However, since it is necessary to set an appropriate position of the light guide 50 according to individual differences, it is better to set the eye box diameter φ larger. Further, considering that the light guide 50 is applied to a glasses-type virtual image display device as will be described later, the eye relief L is generally required to be 15 mm or more.

Therefore, for example, when the eye relief is set to 20 mm and the eye box is set to 5 mm or more and 10 mm or less, the width w of the second surface 103b is 0.5 [mm] <w <3.0 [mm].
It is necessary to satisfy the conditions.

  When the width w of the second surface 103b of the image extraction unit 103 is less than 0.5 mm, it is necessary to shorten the width of the first surface 103a, and the diffraction phenomenon of the incident image light is likely to occur, and the manufacturing is difficult. Undesirable because it becomes difficult. Further, in order to ensure the eye box 5 mm or more and 10 mm or less at the position of the eye relief 20 mm without shortening the width of the first surface 103a, it is necessary to increase the thickness of the light guide, which is desirable because the weight increases. Absent.

  On the other hand, when the width w of the second surface 103b exceeds 3.0 mm, the density of the light beam that is reflected from the first surface 103a and emitted from the light beam emitting unit 104 for the incident image light decreases, and the position of the eye This is not desirable because the amount of light at is reduced. Therefore, it is desirable that the width w of the second surface 103b of the image extraction unit 103 satisfies the condition of 0.5 [mm] <w <3.0 [mm].

  The width w of the second surface 103b may be a different value for each second surface 103b. Specifically, since the light beam density of image light decreases as the distance from the reflection unit 102 increases, it is preferable to set the width w of the second surface 103b to be smaller as the distance from the reflection unit 102 increases. . With this setting, the number of arrangements per unit length of the first surface 103a increases as the distance from the reflecting portion 102 increases, so that unevenness in the amount of light can be reduced.

  Similarly, in order to reduce unevenness in the amount of light, the width of the first surface 103a of the image extraction unit 103 may be different for each first surface 103a. Here, the width of the first surface 103a is the length of the first surface 103a in the direction along the longitudinal direction of the light guide member 100, that is, the direction along the traveling direction of the incident image light. Specifically, the width of the first surface 103a may be set to increase as the distance from the reflecting portion 102 increases. With this setting, the area of the first surface 103a increases as the distance from the reflecting portion 102 increases, and thus the amount of light unevenness can be reduced.

  The thickness of the light guide 50 is desirably in the range of 1 mm to 8 mm. If the thickness of the light guide 50 is less than 1 mm, it is difficult to form the shape of the image extraction portion 103 of the light guide member 100. On the other hand, if the thickness of the light guide 50 exceeds 8 mm, it is advantageous for obtaining a wide viewing angle, but it is not preferable because the weight of the member increases.

(Optical member)
Next, the configuration of the optical member 200 and the arrangement of the optical member 200 with respect to the light guide member 100 will be described. 6 shows an enlarged boundary surface between the light guide member 100 and the optical member 200. In FIG. 6, a virtual plane parallel to the front surface 210 of the optical member 200 is indicated by a dotted line.

  As shown in FIG. 6, in the optical member 200, the inclined portion 203 is disposed close to the image extraction portion 103 of the light guide member 100 via an air layer, that is, an air gap 140. In this embodiment, the edge of the image extraction part 103 of the light guide member 100 and the edge of the inclined part 203 of the optical member 200 are bonded together using a microball type adhesive. By doing in this way, it becomes possible to make the air gap 140 of the taking-out part 103 and the inclination part 203 into equal intervals, and see-through property can be improved more.

  The inclined portion 203 of the optical member 200 includes a third surface 203 a having an angle θa ′ with respect to the front surface 210 and an angle with θb ′ with respect to the front surface 210 at a portion facing the image extracting portion 103 of the light guide member 100. The fourth surfaces 203b having the positions are alternately arranged.

  The front surface 210 is a surface parallel to the light emitting portion 104 of the light guide member 100. The fourth surface 203b is parallel to the front surface 210, and the angle θb ′ = 0 °. Therefore, the fourth surface 203b is parallel to the light emitting portion 104 and the second surface 103b of the light guide member 100, and θb = θb ′ = 0 °. With such setting, the see-through property of the light guide 50 can be enhanced. In addition, when the 4th surface 203b is not a surface parallel to the front surface 210, the light emission part 104 of the light guide member 100, and the 2nd surface 103b, since see-through property falls by a prism effect, it is unpreferable.

  Furthermore, it is preferable to set the angle θa ′ of the third surface 203 a with respect to the front surface 210 to be equal to the angle θa described above, that is, the angle of the image extracting unit 103 with respect to the light emitting unit 104. In this case, the third surface 203 of the optical member 200 is parallel to the first surface 103a of the light guide member 100, and the see-through property of the light guide 50 can be further improved.

  In order to obtain the maximum effect on the see-through property of the light guide 50, the first surface 103a of the light guide member 100 is opposed when translated in the normal direction (upward direction in FIG. 6) of the light emitting portion 104. It is only necessary to eliminate as much as possible the deviation from the third surface 203a. In order to eliminate such a deviation, the optical member 200 can be provided with an adjustment mechanism that adjusts the distance between the light guide member 100, that is, the air gap 140.

  In order to ensure the see-through property of the light guide 50, the light guide member 100 and the optical member 200 are preferably made of the same material.

  The air gap 140 between the take-out portion 103 and the inclined portion 203 can intervene with various gases and liquids, but it is desirable that the air is air from the viewpoint of ensuring see-through performance.

(Modification of light guide member)
Another configuration example of the light guide member 100 will be described with reference to FIGS. 7 and 8.

  In the embodiment shown in FIG. 6 described above, the image extraction unit 103 is configured by two planes, a first surface 103a and a second surface 103b. In other words, the image extraction unit 103 has a first surface 103 a having an angle θa with respect to the light emitting unit 104 and a second surface 103 b having an angle θb with respect to the light emitting unit 104. It has a stepped shape.

  On the other hand, in the modification shown in FIG. 7, the image extraction unit 103 is configured by four planes and has a sawtooth shape. Specifically, the image extraction unit 103 includes a first surface 103a having an angle θa with respect to the light emitting unit 104, a second surface 103b having an angle θb, and an inclined surface 103c having an angle θc. A plane 103d having an angle θd has a shape arranged in this order. In the image extraction unit 103, the first surface 103a and the inclined surface 103c both rise from the reference plane parallel to the light emitting unit 104 and are inclined, but the rising directions are different from each other.

  Among the above four surfaces, the functions and optimum ranges of the first surface 103a and the second surface 103b are the same as in the above-described embodiment, and the description thereof is omitted.

  The inclined surface 103 c has a role of ensuring a large area of the first surface 103 a and a role of improving the bending strength of the light guide member 100.

  The angle θc of the inclined surface 103c with respect to the light emitting part 104 is set to a range greater than 0 ° and 90 ° or less. When the angle θc is 0 °, the inclined surface 103c is the same surface as the second surface 102b, that is, a part of the second surface 102b, and thus has the same configuration as the above-described embodiment. In addition, the angle θc is preferably in the range of 45 ° to 90 ° in consideration of productivity. Furthermore, since the phenomenon such as irregular reflection occurs when the inclined surface 103c is irradiated with the image light from the image display element 10, it is preferable that the inclined surface 103c has an angle range in which the image light from the image display element 10 is not as much as possible.

  The plane 103 d is a part mainly for maintaining see-through property, and it is desirable that the angle θd = 0 ° with respect to the light emitting part 104, that is, parallel to the light emitting part 104. When the angle θd = 0 °, the image light from the image display element 10 can be reflected by the plane 103d as in the second surface 102b.

  Furthermore, as a further modification of the form shown in FIG. 7, the first surface 103a and the inclined surface 103c are in contact with the image extraction unit 103 by extending the first surface 103a and the inclined surface 103c upward in the figure. A three-plane configuration may be used. In this case, the image extracting unit 103 includes a first surface 103 a having an angle θa with respect to the light emitting unit 104, a second surface 103 b having an angle θb with respect to the light emitting unit 104, and the light emitting unit 104. On the other hand, the inclined surface 103c having an angle θc is continuously arranged in this order.

  As described above, the image extraction unit 103 has a three-plane configuration or a four-plane configuration, so that it has a complicated shape as compared with the embodiment shown in FIG. The area can be relatively wide. Accordingly, it is possible to ensure a relatively large amount of image light emitted from the light emitting unit 104. Further, by adopting such a shape, it is possible to improve the bending strength, and it is particularly advantageous when the light guide member 100 is made of resin. That is, when the light guide member 100 is formed of resin, the bending strength is weakened on the tip side where the thickness of the light guide member 100 is reduced, but the bending strength can be improved by adding the inclined surface 103c.

  FIG. 8 shows an enlarged boundary surface between the light guide member 100 and the optical member 200 when the image extraction unit 103 has a four-plane configuration. In the example shown in FIGS. 8A and 8B, the optical member 200 is disposed close to the image extraction unit 103 of the light guide member 100 via air, that is, an air gap 140.

  In the example shown in FIG. 8, the optical member 200 has the inclined portion 203 having the shape described in FIG. That is, in the inclined portion 203 of the optical member 200, the third surface 203a having an angle θa ′ with respect to the front surface 210 and the fourth surface 203b having an angle θb ′ with respect to the front surface 210 are alternately arranged. It has a two-sided structure. The angles θa ′ and θb ′ are as described in the description of FIG. 6, and the angle θa = θa ′ and the angle θb = θb ′. Also in this example, by setting the refractive index of the adhesive 150 to be equal to or lower than the refractive index of the material of the light guide member 100, high see-through performance can be maintained.

  The modification in which the inclined surface 103c and the plane 103d are added to make the image extraction unit 103 have a three-plane configuration or a four-plane configuration is not limited to the configuration applied to the entire image extraction unit 103, and is applied to a part of the image extraction unit 103. May be. That is, while the first surface 103a and the second surface 103b are alternately arranged on the basis of the configuration of the image extracting unit 103 illustrated in FIG. Can add the plane 103d individually.

  Furthermore, when the image extraction unit 103 has a shape of a three-plane configuration or a four-plane configuration, the inclined portion 203 of the optical member 200 that is opposed to the image extraction unit 103 can have a shape corresponding to the three-plane or four-plane deformation shape. . In this case, as described above, when the first surface 103a of the light guide member 100 is translated in the normal direction of the light emitting portion 104, the deviation from the third surface 203a of the opposing optical member 200 is shifted. By adopting a shape that does not occur, the see-through property of the light guide 50 is improved. In order to eliminate such a deviation, an adjustment mechanism that adjusts the distance between the light guide member 100 and the optical member 200 can be attached.

  Thus, according to the various embodiments described above, a light guide having a compact and wide viewing angle of 40 degrees or more is realized.

  In the embodiment shown in FIGS. 1 to 8 described above, the example in which the light beam incident portion 101 of the light guide member 100 is arranged on the left side of the virtual image observer and the image light is incident from the left side of the virtual image observer has been described. When the arrangement is reversed left and right, that is, when the light beam incident portion 101 of the light guide member 100 is arranged on the right side of the virtual image observer and the image light is incident from the right side of the virtual image observer, the same effect as described above is obtained. can get.

  FIGS. 9A, 9B, and 9C illustrate a case where the light guide 50 described above is applied to a glasses-type virtual image display device, that is, an HMD.

  The example shown in FIG. 9A is a case where one light guide 50 is applied to an HMD for both eyes, and the light incident portion 101 of the light guide member 100 is arranged on the right side of the virtual image observer, that is, the user. . The light guide 50 is fixed to the frame part 400 that plays a role as a vine hung on the user's ear. Although the frame portion is simplified in FIG. 9, the frame portion 400 can have a shape that covers not only both ends of the light guide 50 but also the upper edge and the lower edge.

  On the other hand, the example shown in FIGS. 9B and 9C is a case where one light guide 50 is downsized and applied to a monocular HMD. The example shown in FIG. 9B is a case where the two light guides 50 and 50 are arranged corresponding to the positions of the left and right eyes of the user, and the light beam incident portions 101 of the respective light guides are arranged on the left and right outer sides. Is done.

  Although illustration of the virtual image optical system and the light source is omitted in FIG. 9, these can be attached to the frame unit 400. That is, in the example shown in FIGS. 9A and 9C, the light source SL, the image display element 10, and the collimating optical system 300 are arranged in the right eye frame, and in the example shown in FIG. What is necessary is just to attach to a part.

  In the above-described embodiment, the case where the light guide 50 is applied to the eyeglass-type HMD has been described. The light guide 50 described above can be applied to other types of HMDs, and can also be applied to a head-up display (HUD). The light guide 50 is particularly suitable for displaying a virtual image of an original image formed by a light beam optically modulated by a micro device.

  As described above, according to the above-described embodiment, it is possible to provide a transmissive light guide that is small and has a wide viewing angle of 40 degrees or more, and a virtual image display device that can realize the light guide in a compact manner.

(Example of virtual image display device)
A specific example of the virtual image display device manufactured using the light guide 50 described above with reference to FIGS. 1 to 6 will be described with reference to FIGS. 10 and 11. FIGS. 10 and 11 show the emission state of the image light with the light guides of Examples 1 and 2, respectively, and the position of the eye relief is represented by a straight line ER and added with reference to dimensions and the like. Illustration of the element 10, the collimating optical system 300, etc. is omitted. Moreover, each angle shown below is an absolute value display.

Example 1
In Example 1 shown in FIG. 10, the thickness (thickness) of the light guide t ₁ = 1 mm, the length in the longitudinal direction L ₁ = 50 mm, the width = 40 mm, the angle θ 0 = 30 degrees, the refractive index of the light guide (Nd) = 1.54 (plastic). Further, the horizontal viewing angle of the light guide is set to 45 degrees or more, and the width w of the second surface 103b that achieves an eye box of 5 mm or more at an eye relief of 19 mm is set to 2.20 mm.

  In Example 1, the thickness of the light guide can be set to 1 mm, and weight reduction is realized. Therefore, the light guide of Example 1 is suitable for application to a virtual image display device for each eye shown in FIGS. 9B and 9C, for example.

(Example 2)
In Example 2 shown in FIG. 11, the length L ₁ , the width, the angle θ 0, and the refractive index (Nd) of the light guide are the same as those in Example 1, and the light guide thickness (thickness) t ₁ = 4 mm. did. In Example 2, the horizontal viewing angle of the light guide is set to 45 ° or more, and the width w of the second surface 103b that achieves an eye box of 5 mm or more at an eye relief of 19 mm is set to 0.90 mm.

  In the second embodiment, the width of the second surface 103b can be made narrower than in the first embodiment, and as a result, as can be seen from the first embodiment shown in FIG. I was able to.

DESCRIPTION OF SYMBOLS 10 Image display element 300 Collimating optical system LS Light source 50 Light guide 100 Light guide member 101 Light incident part 103 Image extraction part 103a 1st surface 103b 2nd surface 103c Inclined surface 103d Plane 104 Light emission part 140 Air gap 200 Optical member 210 Front (Parallel plane)
203 Inclined part

Patent 4508655 Patent 4512285 Japanese Patent No. 5703875

Claims (10)

A light guide for a virtual image display device that guides image light from an image display element and emits it to display a virtual image,
A light guide member including a light beam incident part on which the image light is incident and a light beam emission part for emitting the image light to the outside; and an optical member provided integrally with the light guide member. ,
The light guide member is a reflective part that guides image light that is inclined with respect to the light incident part and is incident on the light incident part into the light guide;
The first surface inclined with respect to the light emitting portion and the second surface parallel to the light emitting portion are alternately arranged, and the image light is guided from the first surface to the light emitting portion and taken out. Part
The optical guide has a parallel surface parallel to the light emitting portion, and an inclined portion that is inclined with respect to the parallel surface and is disposed in proximity to the image extraction portion. The direction of the inclination of the first surface with respect to the light emitting part is opposite to the direction of the inclination of the reflecting part with respect to the light incident part,
The light guide according to claim 1, wherein an inclination angle of the first surface with respect to the light emitting portion is equal to an inclination angle of the reflecting portion with respect to the light incident portion. The inclined portion of the optical member is
The light guide according to claim 1, wherein third surfaces that are inclined with respect to the parallel surface and fourth surfaces that are parallel to the parallel surface are alternately arranged. 4. The light guide according to claim 1, wherein a width: w [mm] of the second surface in the image extraction portion of the light guide member satisfies the following condition.
0.5 [mm] <w <3.0 [mm]   5. The light guide according to claim 1, wherein an inclination angle of the first surface with respect to the light emitting portion of the light guide member is equal to an inclination angle of the third surface with respect to the parallel surface of the optical member.   The light guide according to any one of claims 1 to 5, wherein a width of the second surface in the image extraction portion of the light guide member is different for each second surface.   The light guide according to any one of claims 1 to 6, wherein a width of the first surface in the image extraction portion of the light guide member is different for each first surface.   The light guide according to claim 1, wherein the optical member is formed of the same material as the light guide member.   The light guide according to claim 1, wherein the light guide member and the optical member are disposed via an air gap. A light source that emits illumination light;
An image display element that receives illumination light from the light source and outputs image light of a display image for virtual image display;
A collimating optical system for collimating and emitting image light from the image display element;
The light guide according to any one of claims 1 to 9, which guides and emits image light from the collimating optical system;
As a virtual image display optical system.