Virtual image display device and optical unit

Abstract

To prevent the appearance of a cross line derived from an optically imperfect part of a cross dichroic prism that combines rays of video light from a plurality of display panels, thereby increasing brightness.SOLUTION: A virtual image display device comprises: a first projection optical system 21a that collimates first video light from a first display panel 11a that emits first video light ML1; a second projection optical system 21b that collimates fourth video light ML2 emitted from a composition optical system 18 that combines second video light MLb emitted from a second display panel 11b and third color video light MLc emitted from a third display panel 11c; a light guide plate group 51 that guides the rays of the first, second, and third video light; first and second incident diffraction optical systems 51b, 52b that make the rays of first and fourth video light incident on the light guide plate group 51; and an output diffraction optical system 51c that emits the rays of first and fourth video light so that they overlap each other. An optical path from the first projection optical system to the first incident diffraction optical system, and an optical path from the second projection optical system to the second incident diffraction optical system are independent of each other.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable viewing of a virtual image. [Background technology]

[0002] A head-mounted display device is known which comprises a cross dichroic prism, multiple display panels, and a projection optical system, the cross dichroic prism having four triangular prisms, a dichroic film provided between adjacent triangular prisms, and an optically imperfect portion at the center of the junction of the four triangular prisms, and the ratio of the air-equivalent length from each of the multiple display panels arranged on the light incident surface of the cross dichroic prism to the center of the junction to the width of the optically imperfect portion is 250:1 or greater (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-003710 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the head-mounted display device shown in the above Patent Document 1, cross lines resulting from optical imperfections may become visible due to the miniaturization of the cross dichroic prism accompanying the miniaturization of the panel and the increase in the F-number of the projection optical system. In addition, since the color separation performance of the cross dichroic prism depends on the angle of incidence of the light emitted from the display panel to the dichroic film, the incidence angle characteristic needs to be about 45 degrees ± 7 degrees. Therefore, the main ray of the light emitted from the display panel needs to be approximately perpendicular (telecentric) to the emission surface of the display panel, and the viewing angle cannot be large. Furthermore, when the display panels of RGB (red, green, blue) are the same, the aperture ratios of each are also approximately the same, so the brightness (luminance) of the display panels of each color needs to be limited to the one with the smallest luminance among these display panels. [Means for solving the problem]

[0005] A virtual image display device and an optical unit in one aspect of the present invention include a first display panel that emits a first image light, a first projection optical system that collimates the first image light from the first display panel, a second display panel that emits a second image light, a third display panel that emits a third image light, a combining optical system that combines the second image light and the third image light and outputs the combined light as a fourth image light, a second projection optical system that collimates the fourth image light from the combining optical system, a light guide plate group that guides the first image light, the second image light, and the third image light, a first entrance diffraction optical system that makes the first image light from the first projection optical system incident on the light guide plate group, a second entrance diffraction optical system that makes the fourth image light from the combining optical system incident on the light guide plate group, and an exit diffraction optical system that emits the first image light and the fourth image light from the light guide plate group so as to overlap each other, and an optical path from the first projection optical system to the first entrance diffraction optical system and an optical path from the second projection optical system to the second entrance diffraction optical system are independent of each other. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a diagram illustrating a state in which the HMD according to the first embodiment is worn. [Diagram 2]FIG. 2 is a side view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Diagram 3] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 4] FIG. 4 is a partial perspective rear view illustrating a light-guiding optical system or a light-guiding member. [Diagram 5] FIG. 1 is a plan view illustrating an optical system using a dichroic prism. [Figure 6] FIG. 11 is a diagram illustrating reduction of chromatic aberration. [Figure 7] FIG. 4 is a partial perspective rear view illustrating a light-guiding optical system or a light-guiding member. [Figure 8] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 9] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 10] FIG. 4 is a partial perspective rear view illustrating a light-guiding optical system or a light-guiding member. [Figure 11] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 12] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. [Figure 13] FIG. 2 is a plan view for explaining the arrangement of an optical system that constitutes the virtual image display device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [First embodiment] Hereinafter, a first embodiment of virtual image display devices 100A and 100B according to the present invention will be described with reference to FIGS.

[0008] Fig. 1 is a diagram for explaining the wearing state of a head mounted display device (hereinafter also referred to as a head mounted display or HMD) 200, in which the observer or wearer US wearing the HMD 200 recognizes an image as a virtual image. In Fig. 1 etc., X, Y, and Z are an orthogonal coordinate system, the +X direction corresponds to the lateral direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are aligned, the +Y direction corresponds to the upward direction perpendicular to the lateral direction in which the eyes EY are aligned for the wearer US, and the +Z direction corresponds to the forward direction or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a first virtual image display device 100A for the left eye, a second virtual image display device 100B for the right eye, a pair of temple-shaped support devices 100C for supporting the virtual image display devices 100A and 100B, and a user terminal 90 that is an information terminal. The first virtual image display device 100A functions as an HMD by itself, and is composed of a first display drive unit 102a arranged at the top, and a first light guide optical system 103a that is shaped like a pair of glasses and covers the front of the eyes. The second virtual image display device 100B also functions as an HMD by itself, and is composed of a second display drive unit 102b arranged at the top, and a second light guide optical system 103b that is shaped like a pair of glasses and covers the front of the eyes. The support device 100C is a mounting member that is mounted on the head of the wearer US, and supports the upper end sides of the pair of light guide optical systems 103a and 103b via the display drive units 102a and 102b that are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically reversed from left to right, and a detailed description of the second virtual image display device 100B will be omitted.

[0010] Fig. 2 is a side view specifically explaining the first display driving unit 102a and the first light guiding optical system 103a of the first virtual image display device 100A. Fig. 3 is a plan view specifically explaining the first display driving unit 102a and the first light guiding optical system 103a. Fig. 4 is a rear view mainly explaining the first light guiding optical system 103a.

[0011] 2 and 3, the first display driving unit 102a includes an image light generating device 10, a projection optical system 20, and a driving circuit member 88. The image light generating device 10 is an optical engine including display panels 11a, 11b, and 11c. The projection optical system 20 is a collimator including a plurality of lens elements 21a and 21b. The image light ML1 and ML2 generated by the image light generating device 10 are collimated by the first lens element 21a and the second lens element 21b of the projection optical system 20, respectively, and are coupled to the first light guiding optical system 103a, which is the light guiding members 51, 52, and 53. The optical axis AX1 of the first lens element 21a and the optical axis AX2 of the second lens element 21b are separated from each other in both the X direction and the Y direction. The driving circuit member 88 causes the display panels 11a, 11b, and 11c to perform a display operation. In the first virtual image display device 100A, an optical device excluding the driving circuit member 88 is referred to as an optical unit 100. The first virtual image display device 100A guides the image lights ML1 and ML2 to the eye EY of the wearer US, thereby allowing the wearer US to view a virtual image.

[0012] 3 and 4, the first light guide optical system 103a is a light guide member 51, 52, 53 that enables color display, and extends approximately parallel to the XY plane. The first light guide optical system 103a has light guide plates 51a, 52a, 53a, incident diffraction layers 51b, 52b, 53b, pupil enlargement grating layers 51d, 52d, 53d, and exit diffraction layers 51c, 52c, 53c. In the first light guide member 51, the first incident diffraction layer 51b, the first exit diffraction layer 51c, and the first pupil enlargement grating layer 51d diffract light in accordance with the wavelength of the first image light ML1 emitted from the first display panel 11a. The first input diffraction layer 51b guides the collimated first image light ML1 from the projection optical system 20 into the first light guide plate 51a and propagates it laterally, the first pupil enlargement grating layer 51d propagates the first image light ML1 propagating laterally within the first light guide plate 51a downward while expanding the pupil size of the first image light ML1, and the first output diffraction layer 51c expands the pupil size of the first image light ML1 propagating downward within the first light guide plate 51a and emits the first image light ML1 toward a pupil position PP (see Figure 2) set inside where the eye EY (see Figure 2) is located.

[0013] Similarly, in the second light guiding member 52, the second incident diffraction layer 52b, the second exit diffraction layer 52c, and the second pupil enlargement grating layer 52d diffract the second image light ML2 according to the wavelength of the component originating from the second display panel 11b. In the third light guiding member 53, the third incident diffraction layer 53b, the third exit diffraction layer 53c, and the third pupil enlargement grating layer 53d diffract the second image light ML2 according to the wavelength of the component originating from the third display panel 11c. Here, the second image light ML2 is a combination of the image lights respectively emitted from the second display panel 11b and the third display panel 11c.

[0014] The second input diffraction layer 52b guides a portion of the collimated second image light ML2 from the projection optical system 20 into the second light guide plate 52a and propagates it laterally, the second pupil enlargement grating layer 52d propagates the portion of the second image light ML2 propagating laterally in the second light guide plate 52a downward while expanding the pupil size of the portion of the second image light ML2 propagating downward in the second light guide plate 52a, and the second output diffraction layer 52c expands the pupil size of the portion of the second image light ML2 propagating downward in the second light guide plate 52a and emits the portion of the second image light ML2 toward a pupil position PP (see Figure 2) set inside where the eye EY (see Figure 2) is located.

[0015] In addition, the third input diffraction layer 53b guides a portion of the collimated second image light ML2 from the projection optical system 20 into the third light guide plate 53a and propagates it laterally, the third pupil enlargement grating layer 53d propagates the portion of the second image light ML2 propagating laterally in the third light guide plate 53a downward while expanding the pupil size of the portion of the second image light ML2 propagating downward in the third light guide plate 53a, and the third output diffraction layer 53c expands the pupil size of the portion of the second image light ML2 propagating downward in the third light guide plate 53a and emits the portion of the second image light ML2 toward a pupil position PP (see Figure 2) set inside where the eye EY (see Figure 2) is located.

[0016] The first exit diffraction layer 51c, the second exit diffraction layer 52c, and the third exit diffraction layer 53c are arranged to overlap one another. The first image light ML1 exiting from the first exit diffraction layer 51c, a part of the second image light ML2 exiting from the second exit diffraction layer 52c, and a part of the second image light ML2 exiting from the third exit diffraction layer 53c are observed as one virtual image formed by the three image lights overlapping and being combined, as viewed from the eye EY (see FIG. 2).

[0017] 2 and 3, a part of the projection optical system 20 through which the first image light ML1 passes from the first display panel 11a until it is incident on the first light guide plate 51a via the first incident diffraction layer 51b will be described. The projection optical system 20 includes one or more optical elements such as lenses, and functions as a collimator that collimates the first image light ML1 from the first display panel 11a. In the example of FIGS. 2 and 3, the first lens element 21a is shown as a part of the projection optical system 20, but this configuration is merely an example and does not limit the present embodiment.

[0018] The first display panel 11a emits one color component of the three primary colors of RGB contained in a virtual image observed by the wearer US. As an example, the first display panel 11a has pixels arranged two-dimensionally for emitting a B (blue) component of image light. The first display panel 11a and the first lens element 21a as the projection optical system 20 are fixed in a state in which they are positioned relative to each other by a lens barrel (not shown) or the like. The lens barrel is supported together with the drive circuit member 88 by a holder 71 (see FIG. 2) that also serves as a cover in a state in which they are positioned relative to each other, and is fixed to the first light guiding optical system 103a.

[0019] 2 and 3, a part of the projection optical system 20 through which the second image light ML2 passes from the second display panel 11b and the third display panel 11c through the second incident diffraction layer 52b and the third incident diffraction layer 53b until it is incident on the second light guide plate 52a and the third light guide plate 53a will be described. The projection optical system 20 includes a synthesis optical system such as a dichroic prism 18 and one or more optical elements such as lenses, and functions as a collimator that collimates the first image light ML1 from the first display panel 11a. In the example of FIG. 2 and FIG. 3, the dichroic prism 18 and the second lens element 21b are shown as part of the projection optical system 20, but this configuration is merely an example and does not limit the present embodiment. As another example, a plate-shaped dichroic film may be provided instead of the dichroic prism 18.

[0020] The second display panel 11b and the third display panel 11c each emit two color components of the three primary colors of RGB contained in a virtual image observed by the wearer US. As an example, the second display panel 11b has pixels arranged two-dimensionally for emitting a G (green) component of the image light, and the third display panel 11c has pixels arranged two-dimensionally for emitting an R (red) component of the image light. The second display panel 11b, the third display panel 11c, the dichroic prism 18 as the synthesis optical system, and the second lens element 21b as the projection optical system 20 are fixed in a mutually positioned state by a lens barrel (not shown) or the like. The lens barrel is supported together with the drive circuit member 88 in a mutually positioned state by a holder 71 (see FIG. 2) also serving as a cover, and is fixed to the first light guiding optical system 103a.

[0021] The first display panel 11a is a display element or display device that emits a first color image light as a first image light ML1 to form a first color component of an image corresponding to a virtual image. The second display panel 11b and the third display panel 11c are display elements or display devices that emit a second color image light and a third color image light that are combined to form a second image light ML2 to form a second color component and a third color component of an image corresponding to the virtual image. Specifically, the first display panel 11a, the second display panel 11b, and the third display panel 11c are displays of various light-emitting element arrays such as OLED (Organic Light Emitting Diode), organic EL (Organic Electro-Luminescence), inorganic EL, and LED, and form still images or moving images on a two-dimensional display surface parallel to the XY plane. The first display panel 11a, the second display panel 11b, and the third display panel 11c have light-emitting elements. A light-emitting element is a multiplicity of pixels arranged two-dimensionally along the XY plane on a substrate. When the first display panel 11a, the second display panel 11b, and the third display panel 11c are OLED displays, each pixel constituting the light-emitting element includes, in that order from the substrate side, a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, and a transparent electrode layer.

[0022] The first display panel 11a, the second display panel 11b, and the third display panel 11c are not limited to self-luminous image light generating devices, and may be composed of LCDs or other light modulation elements, and may form images by illuminating the light modulation elements with a light source such as a background. Instead of LCDs, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), digital micromirror devices, etc. may also be used as the first display panel 11a, the second display panel 11b, and the third display panel 11c.

[0023] The projection optical system 20 includes a first lens element 21a and a second lens element 21b as lens elements that collimate, i.e., parallelize, the incident light. The first lens element 21a as the projection optical system 20 collimates the first image light ML1 emitted from the display surface of the display panel 11a to a state having a predetermined light beam width, and emits the light toward the first incident diffraction layer 51b provided in the first light guide member 51 at an inclination angle state according to the pixel position. The second lens element 21b as the projection optical system 20 collimates the second image light ML2, which is a combination of two image lights emitted from the display surfaces of the display panels 11b and 11c, to a state having a predetermined light beam width, and emits the light toward the second incident diffraction layer 52b provided in the second light guide member 52 and the third incident diffraction layer 53b provided in the third light guide member 53 at an inclination angle state according to the pixel position. The projection optical system 20 may include optical elements such as a reflecting mirror in addition to one or more lens elements made of resin or glass. The optical surfaces of the optical elements constituting the projection optical system 20 may be any of spherical, aspherical, and free-form surfaces.

[0024] As shown in FIG. 5, the dichroic prism 18 as a composite optical system is formed by joining two right-angled triangular prisms 18a and 18b made of a glass material or the like at the side including the hypotenuse of the bottom surface, and has a structure in which a dichroic mirror 180 is embedded in the joining surface. The dichroic prism 18 may have a rectangular parallelepiped or cubic shape having a square bottom surface as a whole. Of the four side surfaces of the dichroic prism 18, the first side surface is fixed so that the second display panel 11b is attached thereto, and functions as a first entrance surface 181 onto which the second-color image light MLb emitted from the second display panel 11b is incident. Similarly, the second side surface is fixed so that the third display panel 11c is attached thereto, and functions as a second entrance surface 182 onto which the third-color image light MLc emitted from the third display panel 11c is incident. The dichroic mirror 180 is disposed on a plane that includes the diagonal line of the bottom surface of the dichroic prism 18 and is perpendicular to the bottom surface, at an angle of 45° with each of the first incident surface 181 and the second incident surface 182. Of the four side surfaces that the dichroic prism 18 has, the third side surface functions as a light exit surface 183 that exits second image light ML2 obtained by combining the second color image light MLb and the third color image light MLc.

[0025] The second-color image light MLb incident on the first entrance surface 181 of the dichroic prism 18 from the second display panel 11b is reflected by the dichroic mirror 180 and bent toward the exit side, i.e., the second lens element 21b serving as the projection optical system 20, and is emitted from the light exit surface in the +Z direction to the outside. The second-color image light MLb incident on the second entrance surface 182 of the dichroic prism 18 from the third display panel 11c passes through the dichroic prism 18 without being reflected by the dichroic mirror 180, and is emitted from the light exit surface 183 of the dichroic prism 18 in the +Z direction to the outside, toward the second lens element 21b serving as the projection optical system 20. As a result, the dichroic prism 18 combines an image by superimposing the second color image light MLb and the third color image light MLc, and the second color image light MLb and the third color image light MLc are emitted as the second image light ML2, and the second image light ML2 can be incident on the lens element 21b as the projection optical system 20.

[0026] As shown in the first region AR1 of Fig. 6, when the second color image light MLb and the third color image light MLc are combined to obtain the second image light ML2, chromatic aberration may occur. In order to reduce such chromatic aberration, an appropriate distance difference may be provided between the optical path length of the second color image light MLb from the second display panel 11b to the pupil position PP and the optical path length of the third color image light MLc from the third display panel 11c to the pupil position PP. More specifically, an appropriate distance difference may be provided between the distance from the second display panel 11b to the first entrance surface 181 of the dichroic prism 18 and the distance from the third display panel 11c to the second entrance surface 182 of the dichroic prism 18. As an example, when the wavelength of the second color is longer than the wavelength of the third color and the material constituting the dichroic prism 18 as the synthesis optical system and the second lens element 21b as the projection optical system 20 has a smaller refractive index for the second color than the refractive index for the third color, the distance from the third display panel 11c that emits the third color image light MLc to the second incident surface 182 of the dichroic prism 18 can be appropriately made shorter than the distance from the second display panel 11b that emits the second color image light MLb to the first incident surface 181 of the dichroic prism 18, thereby reducing the chromatic aberration between the second color image light MLb and the third color image light MLc, as shown in the second region AR2 of Fig. 6. This distance difference may be determined according to the wavelength of the second color and the wavelength of the third color, and the refractive index of each material constituting the optical system through which the second color image light MLb and the third color image light MLc pass. At this time, the optimal position of the second display panel 11b with respect to the first incident surface 181 may first be determined based on the optimal arrangement of the second color image light MLb with respect to the second image light ML2, and then the optimal position of the third display panel 11c with respect to the second incident surface 182 may be determined based on that position.

[0027] Furthermore, by providing an appropriate pitch difference between the pixel pitch of the second display panel 11b and the pixel pitch of the third display panel 11c, chromatic aberration between the second color image light MLb and the third color image light MLc can be reduced. As an example, when the third color image light MLc is projected larger than the second color image light MLb as shown in the second region AR2 of FIG. 6, the pixel pitch of the third display panel 11c is appropriately made shorter than the pixel pitch of the second display panel 11b, so that chromatic aberration between the second color image light MLb and the third color image light MLc can be reduced as shown in the third region AR3 of FIG. 6. Here, the pitch difference between the pixel pitches of the second display panel 11b and the third display panel 11c may be determined based on the wavelengths of the second and third colors, the distance from the second display panel 11b to the first entrance surface 181 of the dichroic prism 18, and the distance from the third display panel 11c to the second entrance surface 182 of the dichroic prism 18. In addition, the size and / or pixel pitch of the first display panel 11a may be larger than the size and / or pixel pitch of the second display panel 11b or the third display panel 11c. In this case, by appropriately adjusting the magnification of the first lens element 21a as the projection optical system 20 according to the size and / or pixel pitch of the first display panel 11a, it is possible to reduce chromatic aberration between the first image light ML1 and the second image light ML2 while making the apparent sizes of the first image light ML1 and the second image light ML2 observed by the exit diffraction layers 51c, 52c, and 53c coincide with each other. Furthermore, when OLEDs are used as the display panels 11a, 11b, and 11c, the brightness of B may be the lowest among RGB. In a configuration in which the B component is emitted from the first display panel 11a that is far from the dichroic prism 18, as described above, it is relatively easy to use the first display panel 11a that is larger than the second display panel 11b and the third display panel 11c, and therefore it becomes relatively easy to increase the brightness of the light-guiding optical systems 103a, 103b as a whole.

[0028] Thus, in this embodiment, instead of adding optical elements such as lens elements to reduce chromatic aberration, the virtual image display devices 100A, 100B and the optical unit 100 are made smaller by adjusting the distance between the display panels 11b, 11c and the incident surfaces 181, 182, changing the pixel pitch of the display panels 11b, 11c, etc.

[0029] Returning to Fig. 4, in the first light guiding member 51 included in the first light guiding optical system 103a, the first incident diffraction layer 51b is a first input diffractive optical element DI1, and is formed with a diffraction pattern that extends linearly in the vertical Y direction and repeats periodically in the horizontal X direction. The first exit diffraction layer 51c is a first output diffractive optical element DO1, and is formed with a diffraction pattern that extends linearly in the horizontal X direction and repeats periodically in the vertical Y direction. The first pupil enlargement grating layer 51d is a first pupil enlargement diffractive optical element DE1, and is provided on the -X side of the first incident diffraction layer 51b, and bends the optical path of the first image light ML1 that is guided into the first light guiding plate 51a and travels in the -X direction as a whole, so that it travels in the -Y direction as a whole.

[0030] The first light guide plate 51a is a member formed from a parallel plate and is a pair of planes extending parallel to the XY plane, and has a first inner total reflection surface 51i on the inner side (-Z direction) as seen by the wearer US, and a first outer total reflection surface 51o on the outer side (+Z direction) as seen by the wearer US (see Figure 2).

[0031] The first entrance diffraction layer 51b, the first exit diffraction layer 51c, and the first pupil enlargement grating layer 51d are formed on a first inner total reflection surface 51i of the first light guide plate 51a.

[0032] The first incident diffraction layer 51b, the first exit diffraction layer 51c, and the first pupil enlargement grating layer 51d diffract the first image light ML1 in accordance with the wavelength thereof, and are formed, for example, of a surface relief type diffraction element. The surface relief type diffraction element is formed by nanoimprinting, but is not limited thereto, and may also be formed by etching the surface of the first light guide plate 51a, or may be formed by attaching a diffraction element.

[0033] The first pupil enlargement grating layer 51d does not substantially impair the angular information of the first image light ML1 in the left-right X direction or the angular information of the first image light ML1 in the up-down Y direction while switching the diffraction direction. The first pupil enlargement grating layer 51d, i.e., the first pupil enlargement diffractive optical element DE1, guides the first image light ML1 guided into the first light guide plate 51a from the first input diffractive optical element DI1, which is the first incident diffraction layer 51b, to the first output diffractive optical element DO1, which is the first exit diffraction layer 51c, while enlarging the pupil of the first exit diffraction layer 51c. More specifically, the first pupil enlargement grating layer 51d is interposed between the first incident diffraction layer 51b and the first exit diffraction layer 51c, and divides the light beam while guiding the first image light ML1 in a direction (-Y direction) intersecting the diffraction direction (-X direction) of the first incident diffraction layer 51b, and has a role of expanding the light beam width in the horizontal direction. The first pupil enlargement grating layer 51d is formed with a diffraction pattern that extends linearly in the DS2 direction parallel to the XY plane and is oblique, and that is periodically repeated in the DS1 direction parallel to the XY plane and perpendicular to the DS2 direction. The DS1 direction is rotated 45° clockwise with respect to the +Y direction, and is an intermediate direction between the -X direction and the +Y direction. The grating period or pitch in the X direction and the Y direction of the pattern formed in the first pupil enlargement grating layer 51d matches the grating period in the X direction of the pattern formed in the first entrance diffraction layer 51b, and matches the grating period in the Y direction of the pattern formed in the first exit diffraction layer 51c. The first exit diffraction layer 51c divides the light beam while guiding the first image light ML1 in the -Y direction, and has a role of expanding the light beam width in the vertical direction. As a result, the beam widths in the X and Y directions of the first image light ML1 incident on the pupil position PP shown in Fig. 2 have an expansion corresponding to the first exit diffraction layer 51c, and the pupil size in the vertical and horizontal directions increases through the first pupil enlargement grating layer 51d, the first exit diffraction layer 51c, etc. The first image light ML1 collimated around the exit optical axis OX (see Fig. 2) perpendicular to the first light guide plate 51a is emitted from the first exit diffraction layer 51c. The first image light ML1 emitted from the first exit diffraction layer 51c is about ±25° with respect to the exit optical axis OX. In other words, the angle of view of the first virtual image display device 100A is about 50°.

[0034] The second light guide member 52 and the third light guide member 53 included in the first light guide optical system 103a are also configured in the same manner as the first light guide member 51. That is, the second light guide member 52 includes a second light guide plate 52a having a second inner total reflection surface 52i and a second outer total reflection surface 52o, a second entrance diffraction layer 52b as the second input diffractive optical element DI2, a second exit diffraction layer 52c as the second output diffractive optical element DO2, and a second pupil enlargement grating layer 52d as the second pupil enlargement diffractive optical element DE2. The second entrance diffraction layer 52b, the second exit diffraction layer 52c, and the second pupil enlargement grating layer 52d are formed on the second inner total reflection surface 52i of the second light guide plate 52a. The third light guide member 53 includes a third light guide plate 53a having a third inner total reflection surface 53i and a third outer total reflection surface 53o, a third entrance diffraction layer 53b as the third input diffractive optical element DI3, a third exit diffraction layer 53c as the third output diffractive optical element DO3, and a third pupil enlargement grating layer 53d as the third pupil enlargement diffractive optical element DE3. The third entrance diffraction layer 53b, the third exit diffraction layer 53c, and the third pupil enlargement grating layer 53d are formed on the third inner total reflection surface 53i of the third light guide plate 53a.

[0035] Here, the first light guide plate 51a, the second light guide plate 52a, and the third light guide plate 53a are disposed facing each other in the thickness direction of each plate. The second incident diffraction layer 52b and the third incident diffraction layer 53b are provided overlapping each other in the direction in which the second light guide plate 52a and the third light guide plate 53a face each other.

[0036] A component of the second color image light MLb having a wavelength of the second color among the second image light ML2 is diffracted by the second entrance diffraction layer 52b and the second pupil enlargement grating layer 52d that diffract light according to the wavelength of the second color, guided by repeating total reflection between the second inner total reflection surface 52i and the second outer total reflection surface 52o inside the second light guide plate 52a, further diffracted by the second exit diffraction layer 52c, and emitted toward the eye EY of the wearer US. Similarly, a component of the third color image light MLc having a wavelength of the third color among the second image light ML2 is diffracted by the third entrance diffraction layer 53b and the third pupil enlargement grating layer 53d that diffract light according to the wavelength of the third color, guided by repeating total reflection between the third inner total reflection surface 53i and the third outer total reflection surface 53o inside the third light guide plate 53a, further diffracted by the third exit diffraction layer 53c, and emitted toward the eye EY of the wearer US.

[0037] At this time, the component of the second image light ML2 that is the third-color image light MLc having the wavelength of the third color is not diffracted by the second incident diffraction layer 52b that corresponds to the wavelength of the second color, and therefore is not guided inside the second light guide plate 52a. Similarly, the component of the second image light ML2 that is the second-color image light MLb having the wavelength of the second color is not diffracted by the third incident diffraction layer 53b that corresponds to the wavelength of the third color, and therefore is not guided inside the third light guide plate 53a.

[0038] In addition, the first incident diffraction layer 51b is disposed at a position where it does not overlap with the second incident diffraction layer 52b and the third incident diffraction layer 53b in the direction in which the first light guide plate 51a, the second light guide plate 52a, and the third light guide plate 53a face each other. More specifically, as shown in FIG. 4, the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b are disposed at a position where they do not overlap with each other in the direction in which the eyes EY of the wearer US are aligned (X direction) and in the up-down direction (Y direction). In other words, the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b are disposed in the DS2 direction, which is a combination of the X direction and the Y direction. As a result, the first image light ML1 emitted from the first display panel 11a is not incident on the second incident diffraction layer 52b and the third incident diffraction layer 53b, is not guided by the second light guide plate 52a and the third light guide plate 53a, and is therefore not guided inside the second light guide plate 52a and the third light guide plate 53a. At this time, as shown in the examples of Figures 2, 3 and 4, the optical path from the first lens element 21a as the first projection optical system 20 to the first incident diffraction layer 51b and the optical path from the second lens element 21b as the second projection optical system 20 to the second incident diffraction layer 52b are independent of each other.

[0039] The first exit diffraction layer 51c, the second exit diffraction layer 52c, and the third exit diffraction layer 53c are provided overlapping in a direction in which the first light guide plate 51a, the second light guide plate 52a, and the third light guide plate 53a face each other. As a result, the first color image light as the first image light ML1 exiting from the first exit diffraction layer 51c, the second color image light MLb of the second image light ML2 exiting from the second exit diffraction layer 52c, and the third color image light MLc of the second image light ML2 exiting from the third exit diffraction layer 53c are observed as one virtual image in an overlapping state by the eye EY of the wearer US.

[0040] [Modification: Arrangement of Incident Diffraction Layer] In the above embodiment, a configuration has been described in which the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b are arranged in positions that do not overlap with each other in the X direction, the Y direction, and the Z direction, as shown in Fig. 4. As a modification of this configuration, the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b may be allowed to be arranged to overlap with each other in the Y direction, as shown in Fig. 7. In this case, the dimensions in the X direction occupied by the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b out of the surface area of ​​the first light guide plate 51a and the surface area of ​​the second light guide plate 52a and the third light guide plate 53a overlapping the first light guide plate 51a are smaller than in the case of Figure 4, so it is expected that the dimensions of the first exit diffraction layer 51c, the second exit diffraction layer 52c, and the third exit diffraction layer 53c can be enlarged in the X direction and the dimensions of the virtual image display devices 100A, 100B and the optical unit 100 in the X direction can be reduced.

[0041] As another modified example of the above configuration, as shown in Fig. 8, the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b may be allowed to overlap in the X direction. In this case, the dimensions of the first incident diffraction layer 51b, the second incident diffraction layer 52b, and the third incident diffraction layer 53b in the Y direction among the surface area of ​​the first light guide plate 51a and the surface area of ​​the second light guide plate 52a and the third light guide plate 53a overlapping with the first light guide plate 51a are smaller than those in Fig. 4, so that it is possible to increase the dimensions of the first exit diffraction layer 51c, the second exit diffraction layer 52c, and the third exit diffraction layer 53c in the Y direction, and to reduce the dimensions of the virtual image display devices 100A and 100B and the optical unit 100 in the Y direction.

[0042] As another modified example of the above configuration, as shown in Fig. 9 and Fig. 10, the first display panel 11a, the first lens element 21a, and the first incident diffraction layer 51b may be disposed at the end of the first light guide plate 51a on the opposite side to the second incident diffraction layer 52b and the third incident diffraction layer 53b in the X direction. That is, the first incident diffraction layer 51b and the second incident diffraction layer 52b may be disposed between the first incident diffraction layer 51b and the second incident diffraction layer 52b and the third incident diffraction layer 53b in the X direction in which the eyes EY of the wearer US are aligned. In this case, the second incident diffraction layer 52b and the third incident diffraction layer 53b may be disposed on the outside of the face of the wearer US, i.e., near the ears, and the first incident diffraction layer 51b may be disposed near the center of the face of the wearer US, i.e., near the nose. In other words, the second incident diffraction layer 52b and the third incident diffraction layer 53b may be disposed on the outer posterior side of the eye EY of the wearer US that observes the first exit diffraction layer 51c and the second exit diffraction layer 52c, as viewed from the first incident diffraction layer 51b, in the X direction in which the eyes EY of the wearer US are aligned. Also, the first display panel 11a, the first lens element 21a, and the first incident diffraction layer 51b may be disposed on the inner posterior side of the eye EY of the wearer US that observes the first exit diffraction layer 51c and the second exit diffraction layer 52c, in the X direction in which the eyes EY of the wearer US are aligned. This is because, from the viewpoint that the wearer US has a relatively large amount of free space near the ears or the corner of the eye, but has a relatively small amount of free space near the nose or the inner corner of the eye, the second incident diffraction layer 52b and the third incident diffraction layer 53b require a dichroic prism 18 having a relatively large volume, but the first display panel 11a does not require a dichroic prism 18. If there is free space near the nose or the inner corner of the eye of the wearer US, the second incident diffraction layer 52b and the third incident diffraction layer 53b may be disposed near the nose or the inner corner of the eye, and the first incident diffraction layer 51b may be disposed near the ear or the corner of the eye.

[0043] As described above, in the virtual image display devices 100A, 100B and the optical unit 100 according to the present embodiment, the second color image light MLb and the third color image light MLc, which are two of the three color components contained in the image light ML1, ML2 of the virtual image that the wearer US wishes to observe, are synthesized into the second image light ML2 by the dichroic prism 18. Furthermore, the first image light ML1, which is the remaining one color component of the three color components, and the second image light ML2 are synthesized in the exit diffraction layers 51c, 52c, and 53c arranged to overlap each other. As a result, in the present embodiment using the dichroic prism 18, cross lines are not generated compared to the case where a cross dichroic prism is used, and there is a margin of brightness, so that a small and high-brightness optical system can be realized and the image quality of the virtual image to be observed can be improved.

[0044] Second Embodiment In the above-described first embodiment, a total of three light guiding members 51, 52, and 53 are used as the light guiding optical system 103a. In this embodiment, as shown in FIG. 11, a total of two light guiding members 51 and 52 are used as the light guiding optical system 103a. The light guiding optical system 103a according to this embodiment is obtained by omitting the third light guiding member 53 from the light guiding optical system 103a according to the first embodiment shown in FIG. 4. However, the second light guiding member 52 according to this embodiment shown in FIG. 11 has the functions of both the second light guiding member 52 and the third light guiding member 53 according to the first embodiment shown in FIG. 4.

[0045] More specifically, in the second light guide member 52 according to this embodiment, the second incident diffraction layer 52b corresponds to both the wavelengths of the second color and the third color, and diffracts both the second color image light MLb and the third color image light MLc included in the second image light ML2, and causes them to enter the inside of the second light guide plate 52a. The second light guide plate 52a totally reflects the incident second color image light MLb and the third color image light MLc between the second inner total reflection surface 52i and the second outer total reflection surface 52o, and guides the light toward the second pupil enlargement grating layer 52d. The second pupil enlargement grating layer 52d according to this embodiment corresponds to both the wavelengths of the second color and the third color, and diffracts the second color image light MLb and the third color image light MLc from the second light guide plate 52a, and causes them to enter again the inside of the second light guide plate 52a. The second light guide plate 52a totally reflects the second color image light MLb and the third color image light MLc that are incident again between the second inner total reflection surface 52i and the second outer total reflection surface 52o, and guides the light toward the second exit diffraction layer 52c. The second exit diffraction layer 52c according to this embodiment corresponds to both the wavelengths of the second color and the third color, and diffracts the second color image light MLb and the third color image light MLc from the second light guide plate 52a and emits them as the second image light ML2. The configuration and function of the first light guide member 51 according to this embodiment are the same as those in the first embodiment. As a result, the first image light ML1 and the second image light ML2 that are respectively emitted from the first exit diffraction layer 51c and the second exit diffraction layer 52c according to this embodiment reach the eye EY of the wearer US in an overlapping state, and the wearer US can observe a virtual image consisting of the first image light ML1 and the second image light ML2.

[0046] As described above, in this embodiment, the number of light-guiding members 51, 52 is reduced compared to the first embodiment, thereby making it possible to reduce the weight, dimensions, and manufacturing costs of the virtual image display devices 100A, 100B and the optical unit 100.

[0047] [Modification: Swapping the Position of the Light Guide Member] In the above embodiment, as shown in Fig. 11, a configuration has been described in which the first light guiding member 51 is disposed on the front side (-Z direction) as viewed from the wearer US with respect to the second light guiding member 52. As a modification of this configuration, as shown in Fig. 12, the positions of the first light guiding member 51 and the second light guiding member 52 may be interchanged. In this case, the distance from the first lens element 21a to the first incident diffraction layer 51b is longer and the distance from the second lens element 21b to the second incident diffraction layer 52b is shorter than the configuration in Fig. 11. By effectively utilizing the difference in these distances, it is expected that the degree of freedom in designing the optical system can be increased.

[0048] Third Embodiment In the above-described second embodiment, a total of two light guiding members 51 and 52 are used as the light guiding optical system 103a. In this embodiment, as shown in Fig. 13, a total of one light guiding member 51 is used as the light guiding optical system 103a. More specifically, the first light guiding member 51 according to this embodiment shown in Fig. 13 serves the functions of both the first light guiding member 51 and the second light guiding member 52 according to the second embodiment shown in Fig. 11.

[0049] The first light guide member 51 according to this embodiment includes a first light guide plate 51a, a first incident diffraction layer 51b, a first pupil enlargement grating layer 51d, a first exit diffraction layer 51c, a second incident diffraction layer 52b, a second pupil enlargement grating layer 52d, and a second exit diffraction layer 52c. In the first light guide member 51, the first incident diffraction layer 51b, the first pupil enlargement grating layer 51d, and the first exit diffraction layer 51c are disposed on a first inner total reflection surface 51i of the first light guide plate 51a, and the second incident diffraction layer 52b, the second pupil enlargement grating layer 52d, and the second exit diffraction layer 52c are disposed on a first outer total reflection surface 51o of the first light guide plate 51a.

[0050] The second incident diffraction layer 52b, the second pupil enlargement grating layer 52d, and the second exit diffraction layer 52c according to this embodiment function in the same manner as in the second embodiment. However, instead of the second light guide plate 52a, the second inner total reflection surface 52i, and the second outer total reflection surface 52o according to the second embodiment, the first light guide plate 51a, the first inner total reflection surface 51i, and the first outer total reflection surface 51o are used, respectively. That is, in this embodiment, the second image light ML2 from the second lens element 21b as the projection optical system 20 passes through the first light guide plate 51a and enters the second incident diffraction layer 52b, is diffracted by the second incident diffraction layer 52b, enters the first light guide plate 51a, and is guided toward the second pupil enlargement grating layer 52d by repeating total reflection between the first inner total reflection surface 51i and the first outer total reflection surface 51o. In the present embodiment, the second image light ML2 from the first light guide plate 51a is further diffracted by the second pupil enlargement grating layer 52d, enters the first light guide plate 51a again, and is guided toward the second exit diffraction layer 52c while repeatedly being totally reflected between the first inner total reflection surface 51i and the first outer total reflection surface 51o, and is diffracted by the second exit diffraction layer 52c and emitted to the outside. Here, at least a part of the second image light ML2 emitted to the outside passes through the first inner total reflection surface 51i and the first exit diffraction layer 51c of the first light guide plate 51a toward the pupil position PP.

[0051] Note that the first entrance diffraction layer 51b, the first pupil enlargement grating layer 51d, and the first exit diffraction layer 51c according to this embodiment function in the same manner as in the case of embodiment 1. That is, in this embodiment, the first image light ML1 from the first lens element 21a as the projection optical system 20 enters the first entrance diffraction layer 51b, is diffracted by the first entrance diffraction layer 51b, enters the first light guide plate 51a, and is repeatedly totally reflected between the first inner total reflection surface 51i and the first outer total reflection surface 51o, and is guided toward the first pupil enlargement grating layer 51d. In addition, in this embodiment, the first image light ML1 from the first light guide plate 51a is further diffracted by the first pupil enlargement grating layer 51d, enters the first light guide plate 51a again, and is guided toward the first exit diffraction layer 51c while repeatedly being totally reflected between the first inner total reflection surface 51i and the first outer total reflection surface 51o. The first image light ML1 is diffracted by the first exit diffraction layer 51c and is emitted to the outside, and at least a part of the first image light ML1 emitted to the outside heads toward the pupil position PP. As a result, the first image light ML1 and the second image light ML2 emitted from the first exit diffraction layer 51c and the second exit diffraction layer 52c according to this embodiment reach the eye EY of the wearer US while overlapping with each other, and the wearer US can observe a virtual image made of the first image light ML1 and the second image light ML2.

[0052] As described above, in this embodiment, the number of light-guiding members 51 is further reduced compared to the second embodiment, thereby making it possible to reduce the weight, dimensions, and manufacturing costs of the virtual image display devices 100A, 100B and the optical unit 100.

[0053] [Variation: the diffractive layer can be disposed on the surface of the inner or outer total reflection surface] In the above embodiment, as shown in Fig. 13, the first incident diffraction layer 51b, the first pupil enlargement grating layer 51d, and the first exit diffraction layer 51c (not shown) are arranged on the surface of the first inner total reflection surface 51i of the first light guide plate 51a, and the second incident diffraction layer 52b, the second pupil enlargement grating layer 52d, and the second exit diffraction layer 52c (not shown) are arranged on the surface of the first outer total reflection surface 51o of the first light guide plate 51a. As a modification of this configuration, these diffraction layers and grating layers may be arranged only on the surface of the first inner total reflection surface 51i, may be arranged only on the surface of the first outer total reflection surface 51o, or may be arranged separately on the surfaces of the first inner total reflection surface 51i and the first outer total reflection surface 51o.

[0054] [Modification: Combination of a display panel attached to a dichroic prism] In the above embodiments, a configuration has been described in which, of the three primary colors contained in the image light, the B (blue) component having the shortest wavelength is emitted from the first display panel 11a, the R (red) component having the longest wavelength is emitted from the third display panel 11c, and the G (green) component having an intermediate wavelength is emitted from the second display panel 11b. As a variation of this configuration, the R component may be emitted from the first display panel 11a, the B component may be emitted from the third display panel 11c, and the G component may be emitted from the second display panel 11b.

[0055] As another modified example, the G component may be emitted from the first display panel 11a, and the R and B components may be emitted from the second display panel 11b and the third display panel 11c. In this case, since the wavelengths of the colors of the two image lights combined by the dichroic prism 18 are relatively far apart, the restriction on the angle of incidence on the dichroic mirror 180 is relaxed compared to the case where the image light includes a G component. As a result, even if a non-telecentric optical system is used as the projection optical system 20 arranged after the dichroic prism 18, the second color image light MLb and the third color image light MLc can be combined into the second image light ML2.

[0056] In the above, the virtual image display devices 100A, 100B can be used as HMDs, but the present invention is not limited to this and can be applied to various optical devices. For example, the present invention can be applied to a head-up display (HUD).

[0057] In addition, the above-described modified examples can be combined with each other within a range that does not cause technical contradiction. For example, the positional relationship on the XY plane of the first incident diffraction layer 51b and the second incident diffraction layer 52b, the total number of light-guiding members 51, 52, and 53 included in the light-guiding optical system 103a, and whether the incident diffraction layers 51b, 52b, and 53b and the pupil enlargement grating layers 51d, 52d, and 53d are disposed on the inner total reflection surfaces 51i, 52i, and 53i or the outer total reflection surfaces 51o, 52o, and 53o of the light-guiding plates 51a, 52a, and 53a can be freely combined.

[0058] A virtual image display device in a specific aspect includes a first display panel that emits a first image light, a first projection optical system that collimates the first image light from the first display panel, a second display panel that emits a second image light, a third display panel that emits a third image light, a combining optical system that combines the second image light and the third image light and outputs the combined light as a fourth image light, a second projection optical system that collimates the fourth image light from the combining optical system, a light guide plate group that guides the first image light, the second image light, and the third image light, a first entrance diffraction optical system that causes the first image light from the first projection optical system to be incident on the light guide plate group, a second entrance diffraction optical system that causes the fourth image light from the combining optical system to be incident on the light guide plate group, and an exit diffraction optical system that emits the first image light and the fourth image light from the light guide plate group to overlap each other, and an optical path from the first projection optical system to the first entrance diffraction optical system and an optical path from the second projection optical system to the second entrance diffraction optical system are independent of each other.

[0059] In the above-mentioned virtual image display device, two of the three components contained in the image light are combined by a combining optical system, and then the remaining color component is further combined by an emission diffraction optical system, making it possible to display a virtual image using a compact optical system.

[0060] In a specific embodiment of the virtual image display device, the first display panel emits a first image light of a first color, the second display panel emits a second image light of a second color different from the first color, the third display panel emits a third image light of a third color different from the first and second colors, and the second entrance diffractive optical element causes the second color and the third color to be incident on the light guide plate group. In this case, two of the three primary color components contained in the image light are combined by the combining optical system, and then the remaining one color component is further combined by the exit diffractive optical system, so that a high-quality virtual image can be displayed with a compact optical system.

[0061] In a specific embodiment of the virtual image display device, the first wavelength of the first color is shorter than the second wavelength of the second color, and the second wavelength of the second color is shorter than the third wavelength of the third color.

[0062] In a specific embodiment of the virtual image display device, the first wavelength of the first color is longer than the second wavelength of the second color, and the second wavelength of the second color is longer than the third wavelength of the third color.

[0063] In a specific embodiment of the virtual image display device, the combining optical system includes a dichroic prism that combines the second color and the third color. The dichroic prism does not have optical imperfections like the cross dichroic prism, and therefore can display a virtual image with relatively high image quality.

[0064] In a specific embodiment of the virtual image display device, the combining optical system includes a dichroic film that combines the second color and the third color. The dichroic film can be substituted for the dichroic prism.

[0065] In a specific embodiment of the virtual image display device, the light guide plate group includes a light guide plate that guides the first image light and the fourth image light, the first incident diffraction optical system includes a first incident diffraction optical element that causes the first image light from the first projection optical system to be incident on the light guide plate, the second incident diffraction optical system includes a second incident diffraction optical element that causes the fourth image light from the second projection optical system to be incident on the light guide plate, and the exit diffraction optical system includes a first exit diffraction optical element provided on a first surface of the light guide plate and that exits the first image light from the light guide plate, and a second exit diffraction optical element provided on a second surface opposite to the first surface of the light guide plate and that exits the fourth image light from the light guide plate, the first exit diffraction optical element and the second exit diffraction optical element being overlapped in the thickness direction of the light guide plate. In this case, the light guide optical system is composed of one light guide member.

[0066] In a virtual image display device according to a specific aspect, the first incidence diffractive optical element and the second incidence diffractive optical element are provided on either the first surface or the second surface, which are different from each other.

[0067] In a virtual image display device according to a specific aspect, the first incidence diffractive optical element and the second incidence diffractive optical element are provided on either the first surface or the second surface.

[0068] In a specific embodiment of the virtual image display device, the light guide plate group includes a first light guide plate that guides the first image light and a second light guide plate that guides the fourth image light, the first incident diffraction optical system makes the first image light from the first projection optical system incident on the first light guide plate, the second incident diffraction optical system makes the fourth image light from the second projection optical system incident on the second light guide plate, and the exit diffraction optical system includes a first exit diffraction optical element that exits the first image light from the first light guide plate and a second exit diffraction optical element that exits the fourth image light from the second light guide plate, and the first exit diffraction optical element and the second exit diffraction optical element are provided overlapping in a direction in which the first light guide plate and the second light guide plate face each other. In this case, the light guide optical system is composed of two light guide members. Here, the first exit diffraction optical element and the second exit diffraction optical element may be provided on the surfaces of the first light guide plate and the second light guide plate, respectively.

[0069] In a specific aspect of the virtual image display device, the light guide plate group includes a first light guide plate that guides a first image light, a second light guide plate that guides a second image light, and a third light guide plate that guides a third image light, and the first incident diffraction optical system causes the first image light from the first projection optical system to be incident on the first light guide plate, and the second incident diffraction optical system causes the second image light from the second projection optical system to be incident on the second light guide plate and the third image light from the second projection optical system to be incident on the third light guide plate, respectively. The exit diffraction optical system includes a first exit diffraction optical element that exits the first image light from the first light guide plate, a second exit diffraction optical element that exits the second image light from the second light guide plate, and a second exit diffraction optical element that exits the third image light from the third light guide plate, and the first exit diffraction optical element, the second exit diffraction optical element, and the third exit diffraction optical element are provided overlapping each other in a direction in which the first light guide plate, the second light guide plate, and the third light guide plate face each other. In this case, the light guide optical system is composed of three light guide members. Here, the first exit diffraction optical element, the second exit diffraction optical element, and the third exit diffraction optical element may be provided on the surfaces of the first light guide plate, the second light guide plate, and the third light guide plate, respectively.

[0070] In a specific embodiment of the virtual image display device, a distance difference is provided between a first optical path length from one of the second and third display panels to the combining optical system and a second optical path length from the other panel to the combining optical system in order to reduce chromatic aberration between the second and third image lights. In this case, chromatic aberration can be reduced without adding any optical element.

[0071] In a specific embodiment of the virtual image display device, a pitch difference is provided between the pixel pitch of the second display panel and the pixel pitch of the third display panel in order to reduce chromatic aberration between the second image light and the third image light, and in this case, the chromatic aberration can be reduced without adding any optical element.

[0072] In a specific embodiment of the virtual image display device, the first wavelength of the first color is longer than the second wavelength of the second color, the third wavelength of the third color is longer than the first wavelength of the first color, and the second projection optical system is non-telecentric. In this case, the red component having the longest wavelength and the blue component having the shortest wavelength among the three primary colors are first synthesized by a dichroic prism or the like, thereby relaxing the restriction on the angle of incidence to the dichroic film, and therefore a non-telecentric optical system can be used as the projection optical system.

[0073] In a specific embodiment of the virtual image display device, the first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in a third direction that combines a first direction in which the wearer's eyes are aligned and a second direction perpendicular to the first direction and the thickness direction of the light guide plate.

[0074] In a virtual image display device according to a specific embodiment, the first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in the direction in which the wearer's eyes are aligned.

[0075] In a specific embodiment of the virtual image display device, the first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in a first direction in which the wearer's eyes are aligned and in a second direction perpendicular to the thickness direction of the light guide plate.

[0076] In a specific embodiment of a virtual image display device, the first incident diffractive optical system is arranged in a first direction in which the wearer's eyes are aligned, on the medial side of the eye of the wearer that observes the exit diffractive optical system, as viewed from the second incident diffractive optical system, and the second incident diffractive optical system is arranged in the first direction on the lateral side of the eye, as viewed from the first incident diffractive optical system.

[0077] In a specific aspect, the optical unit includes a first display panel that emits a first image light, a first projection optical system that collimates the first image light from the first display panel, a second display panel that emits a second image light, a third display panel that emits a third image light, a combining optical system that combines the second image light and the third image light and outputs the combined light as a fourth image light, a second projection optical system that collimates the fourth image light from the combining optical system, a light guide plate group that guides the first image light, the second image light, and the third image light, a first entrance diffraction optical system that makes the first image light from the first projection optical system incident on the light guide plate group, a second entrance diffraction optical system that makes the fourth image light from the combining optical system incident on the light guide plate group, and an exit diffraction optical system that emits the first image light and the fourth image light from the light guide plate group so as to overlap each other, and an optical path from the first projection optical system to the first entrance diffraction optical system and an optical path from the second projection optical system to the second entrance diffraction optical system are independent of each other. [Explanation of symbols]

[0078] 10...image light generating device, 11a, 11b, 11c...display panel, 18...dichroic prism, 180...dichroic mirror, 181, 182...light entrance surface, 183...light exit surface, 20...projection optical system, 21a, 21b...lens element, 51, 52, 53...light guide member, 51a, 52a, 53a...light guide plate, 51b, 52b, 53b...entrance diffraction layer, 51c, 52c, 53c...exit diffraction layer, 51d, 52d, 53d...pupil enlargement grating layer, 71...holder, 88...drive circuit member, 90...u User terminal, 100... optical unit, 100A, 100B... virtual image display device, 100C... support device, 102a, 102b... display drive unit, 103a, 103b... light guide optical system, AX1, AX2... optical axis, DE1, DE2, DE3... pupil enlargement diffractive optical element, DI1, DI2, DI3... input diffractive optical element, DO1, DO2, DO3... output diffractive optical element, EY... eye, ML1, ML2... image light, MLb... second color image light, MLc... third color image light, OX... exit optical axis, PP... pupil position, US... wearer

Claims

1. a first display panel that emits a first image light; a first projection optical system that collimates the first image light from the first display panel; a second display panel that emits a second image light; a third display panel that emits a third image light; a combining optical system that combines the second image light and the third image light and outputs the combined light as a fourth image light; a second projection optical system that collimates the fourth image light from the combining optical system; a light guide plate group that guides the first image light, the second image light, and the third image light; a first incident diffractive optical system that causes the first image light from the first projection optical system to be incident on the light guide plate group; a second incident diffractive optical system that causes the fourth image light from the combining optical system to be incident on the light guide plate group; an emission diffraction optical system that emits the first image light and the fourth image light from the light guide plate group so as to overlap each other; Equipped with An optical path from the first projection optical system to the first incident diffraction optical system and an optical path from the second projection optical system to the second incident diffraction optical system are independent of each other. Virtual image display device.

2. the first display panel emits the first image light of a first color; the second display panel emits the second image light of a second color different from the first color; the third display panel emits the third image light of a third color different from the first color and the second color; The second incident diffractive optical system causes the second color and the third color to be incident on the light guide plate group. The virtual image display device according to claim 1 .

3. a first wavelength of the first color is shorter than a second wavelength of the second color; the second wavelength of the second color is shorter than the third wavelength of the third color; The virtual image display device according to claim 2 .

4. a first wavelength of the first color is longer than a second wavelength of the second color; the second wavelength of the second color is longer than the third wavelength of the third color; The virtual image display device according to claim 2 .

5. The synthetic optical system includes: a dichroic prism for combining the second color and the third color Equipped The virtual image display device according to claim 2 .

6. The synthetic optical system includes: A dichroic film for combining the second color and the third color. Equipped The virtual image display device according to claim 2 .

7. The light guide plate group includes: A light guide plate for guiding the first image light and the fourth image light. Equipped with The first incident diffractive optical system is a first incident diffractive optical element that causes the first image light from the first projection optical system to be incident on the light guide plate; Equipped with The second incident diffractive optical system is a second incident diffractive optical element that causes the fourth image light from the second projection optical system to be incident on the light guide plate; Equipped with The said emission diffractive optical system is a first emission diffractive optical element provided on a first surface of the light guide plate and configured to emit the first image light from the light guide plate; a second emission diffractive optical element provided on a second surface of the light guide plate opposite to the first surface, the second emission diffractive optical element configured to emit the fourth image light from the light guide plate; Equipped with The first emission diffractive optical element and the second emission diffractive optical element are provided so as to overlap each other in a thickness direction of the light guide plate. The virtual image display device according to claim 2 .

8. The first incident diffractive optical element and the second incident diffractive optical element are provided on different surfaces of the first surface and the second surface. The virtual image display device according to claim 7 .

9. The first incident diffractive optical element and the second incident diffractive optical element are provided on one of the first surface and the second surface. The virtual image display device according to claim 7 .

10. The light guide plate group includes: a first light guide plate that guides the first image light; a second light guide plate that guides the fourth image light; Equipped with the first incident diffractive optical system causes the first image light from the first projection optical system to be incident on the first light guide plate; the second incident diffractive optical system causes the fourth image light from the second projection optical system to be incident on the second light guide plate; The said emission diffractive optical system is a first emission diffractive optical element that emits the first image light from the first light guide plate; a second emission diffractive optical element that emits the fourth image light from the second light guide plate; Equipped with the first-emission diffractive optical element and the second-emission diffractive optical element are provided so as to overlap each other in a direction in which the first light guide plate and the second light guide plate face each other; The virtual image display device according to claim 2 .

11. The light guide plate group includes: a first light guide plate that guides the first image light; a second light guide plate that guides the second image light; a third light guide plate that guides the third image light; Equipped with the first incident diffractive optical system causes the first image light from the first projection optical system to be incident on the first light guide plate; The second incident diffractive optical system is the second image light from the second projection optical system to the second light guide plate; the third image light from the second projection optical system to the third light guide plate; Each is injected, The said emission diffractive optical system is a first emission diffractive optical element that emits the first image light from the first light guide plate; a second emission diffractive optical element that emits the second image light from the second light guide plate; a third emission diffractive optical element that emits the third image light from the third light guide plate; Equipped with the first-emission diffractive optical element, the second-emission diffractive optical element, and the third-emission diffractive optical element are provided so as to overlap with each other in a direction in which the first light guide plate, the second light guide plate, and the third light guide plate face each other; The virtual image display device according to claim 2 .

12. a distance difference is provided between a first optical path length from one of the second display panel and the third display panel to the combining optical system and a second optical path length from the other panel to the combining optical system, in order to reduce chromatic aberration between the second image light and the third image light. The virtual image display device according to claim 2 .

13. a pitch difference is provided between a pixel pitch of the second display panel and a pixel pitch of the third display panel in order to reduce chromatic aberration between the second image light and the third image light. The virtual image display device according to claim 2 .

14. a first wavelength of the first color is longer than a second wavelength of the second color; a third wavelength of the third color is longer than a first wavelength of the first color; The second projection optical system is non-telecentric. The virtual image display device according to claim 2 .

15. The first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in a third direction obtained by combining a first direction in which both eyes of a wearer are aligned and a second direction perpendicular to the first direction and a thickness direction of the light guide plate group. The virtual image display device according to claim 1 .

16. The first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in a direction in which both eyes of the wearer are arranged side by side. The virtual image display device according to claim 1 .

17. The first incident diffractive optical system and the second incident diffractive optical system are arranged side by side in a first direction in which both eyes of a wearer are aligned and in a second direction perpendicular to a thickness direction of the light guide plate group. The virtual image display device according to claim 1 .

18. The first incident diffractive optical system is disposed on the head side of one of the wearer's eyes that observes the exit diffractive optical system as viewed from the second incident diffractive optical system in a first direction in which the wearer's eyes are aligned, The second incident diffractive optical system is disposed on the outer posterior side of the eye as viewed from the first incident diffractive optical system in the first direction. The virtual image display device according to claim 1 .

19. a first display panel that emits a first image light; a first projection optical system that collimates the first image light from the first display panel; a second display panel that emits a second image light; a third display panel that emits a third image light; a combining optical system that combines the second image light and the third image light and outputs the combined light as a fourth image light; a second projection optical system that collimates the fourth image light from the combining optical system; a light guide plate group that guides the first image light, the second image light, and the third image light; a first incident diffractive optical system that causes the first image light from the first projection optical system to be incident on the light guide plate group; a second incident diffractive optical system that causes the fourth image light from the combining optical system to be incident on the light guide plate group; an emission diffraction optical system that emits the first image light and the fourth image light from the light guide plate group so as to overlap each other; Equipped with An optical path from the first projection optical system to the first incident diffraction optical system and an optical path from the second projection optical system to the second incident diffraction optical system are independent of each other. Optical unit.

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