Virtual image display device and optical unit

Abstract

To enhance brightness at an exit pupil.SOLUTION: A virtual image display device 100A comprises: display panels 11r,11b,11g for emitting video light ML; a projection optical system 20 for making the video light ML from the display panels 11r,11b,11g emitted; and a light guiding component 50 for guiding the video light ML emitted by the projection optical system 20 to an emission part DO. The display panels 11r,11b,11g have a plurality of display areas 1a,1b, and the projection optical system 20 has a plurality of optical parts 120a,120b that is arranged according to the arrangement direction of the plurality of display areas 1a,1b and guide the video light ML from the display areas 1a,1b to the light guiding component 50. The video light ML emitted by the optical parts 120a,120b is overlappingly projected by an exit pupil EP.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] A known display device that enables the observation of virtual images is one in which the display light emitted from three display panels is combined using a combining optical system equipped with two intersecting dichroic mirrors, and the combined light is made to enter one end of a plate-shaped light-guiding section and exit from the other end (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-205451 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the display device disclosed in Patent Document 1, for example, the light utilization efficiency of the light guide plate is about 1%, and if an optical system with poor light utilization efficiency is used, the brightness of the image light at the exit pupil may be too low to be visible. [Means for solving the problem]

[0005] A virtual image display device or optical unit in one aspect of the present invention comprises a display panel that emits image light, a projection optical system that emits the image light from the display panel, and a light guiding member that guides the image light emitted from the projection optical system to an emission section, wherein the display panel has a plurality of display areas, and the projection optical system has a plurality of optical parts that are arranged in accordance with the arrangement direction of the plurality of display areas and guide the image light from each display area to the light guiding member, and the image light emitted from each optical part is superimposed and projected at the exit pupil. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view illustrating a state in which an HMD according to a 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. 2 is a front view illustrating a light-guiding optical system or a light-guiding member. [Diagram 5] 4 is a side view illustrating the optical system of the first display driving section. FIG. [Figure 6] 4 is a plan view illustrating the optical system of the first display driving section. FIG. [Figure 7] 4 is a perspective view illustrating an optical system of a first display driving unit. FIG. [Figure 8] FIG. 4 is a development view illustrating the optical system of the first display driver. [Figure 9] 4 is a ray diagram illustrating the optical system of the first display driver seen from the side. FIG. [Figure 10] 4 is a plan view of a light ray diagram illustrating the optical system of the first display driver. FIG. [Figure 11] FIG. 11 is a perspective view illustrating an optical system according to a second embodiment. [Figure 12] FIG. 13 is a diagram illustrating an optical system according to a modified example. [Figure 13] 11A and 11B are diagrams illustrating modified examples of a display panel and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0008] FIG. 1 is a diagram for explaining a wearing state of a head mounted display device (hereinafter also referred to as a head mounted display or HMD) 200, and the HMD 200 allows an observer or wearer US wearing the device to recognize an image as a virtual image. In FIG. 1 and the like, X, Y, and Z are Cartesian coordinate systems, and the +X direction corresponds to the horizontal 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 horizontal 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. The +Y direction or upward direction corresponds to the direction from the chin of the face toward the center of the forehead when the HMD 200 is worn by the wearer US.

[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 front 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 a cross-prism type image light emitting unit 11. The projection optical system 20 is a collimator including a plurality of optical parts 120a and 120b. The image light ML generated by the image light generating device 10 is collimated by the projection optical system 20 and coupled to the first light guiding optical system 103a, which is a light guiding member 50. Collimation refers to optically adjusting diffused light to be in a parallel state by an optical element, to make it into collimated light, that is, parallel light. The driving circuit member 88 causes the display panels 11r, 11b, and 11g (see FIG. 5) described later to perform a display operation. In the first virtual image display device 100A, the optical device excluding the driving circuit member 88 is called an optical unit 100. The first display driving unit 102a is supported in a mutually positioned state by a holder 71 also serving as a cover, and is fixed to the first light guiding optical system 103a on the inner -Z side thereof. The first virtual image display device 100A guides the image light ML to the eye EY of the wearer US, thereby allowing the wearer US to view a virtual image.

[0012] 2 to 4, the first light guiding optical system 103a is a light guiding member 50 that enables color display and extends approximately parallel to the XY plane. The first light guiding optical system 103a has a plurality of light guiding plates 51a stacked in parallel. Specifically, the first light guiding optical system 103a includes a first light guiding member 151 and a second light guiding member 152 that diffracts image light ML in a wavelength range different from that of the first light guiding member 151. The first and second light guiding members 151 and 152 each include a light guiding plate 51a, an entrance diffraction layer 51b, an exit diffraction layer 51c, and a pupil enlargement grating layer 51e.

[0013] The first light guiding member 151 and the second light guiding member 152 are optimized according to the wavelength range of the image light ML. The first and second light guiding members 151 and 152 can correspond to three colors, for example, RBG. The light guiding plates 51a of the first and second light guiding members 151 and 152 are assigned to different colors. Specifically, the first light guiding member 151 has a grating period or the like of the incident diffraction layer 51b set so that blue light and green light propagate therethrough. The second light guiding member 152 has a grating period or the like of the incident diffraction layer 51b set so that red light propagates therethrough. Three light guiding members 50 may be provided corresponding to the three colors. Also, one light guiding member 50 may be provided in common for the three colors.

[0014] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e diffract the image light ML according to its wavelength. The incident diffraction layer 51b guides the collimated image light ML from the first display driver 102a (see FIG. 2) into the light guide plate 51a and propagates it laterally. The pupil enlargement grating layer 51e propagates the image light ML propagating laterally in the light guide plate 51a downward while expanding the pupil size of the image light ML. The exit diffraction layer 51c expands the pupil size of the image light ML propagating downward in the light guide plate 51a and causes the image light ML to exit toward a pupil position PP (see FIG. 2) set inside where the eye EY (see FIG. 2) is located.

[0015] Fig. 5 and Fig. 6 are a side view and a plan view of the optical system of the first display driver 102a. Fig. 7 is a conceptual perspective view explaining the optical system of the first display driver 102a. Fig. 8 is a development view of the first display driver 102a shown in Fig. 7.

[0016] In the first display driving section 102a, the image light emitting unit 11 is an optical engine including three display panels 11r, 11b, and 11g, and a cross dichroic prism 18. The optical parts 120a and 120b are collimators including a lens part 21 and an aperture part 22.

[0017] Although the details will be described later, each of the display panels 11r, 11b, and 11g has a plurality of display areas 1a and 1b. In addition, the projection optical system 20 has a plurality of optical parts 120a and 120b arranged in accordance with the arrangement direction of the plurality of display areas 1a and 1b. The number of the optical parts 120a and 120b corresponds to the number of divisions of the display areas 1a and 1b. By dividing the display panels 11r, 11b, and 11g into a plurality of display areas 1a and 1b, it is equivalent to guiding the image light ML to the eye EY using a plurality of light sources, and the luminance at the exit pupil EP (see FIG. 2) can be improved. In addition, since the display panels 11r, 11b, and 11g are provided one by one at one location, and there is no need to provide a plurality of display panels at one location, it is possible to suppress size increase due to margins related to FPC (Flexible Printed Circuit) and panel manufacturing. The optical axes DXa, DXb of the display areas 1a, 1b coincide with the optical axes EXa, EXb of the corresponding optical parts 120a, 120b. Here, the optical axes DXa, DXb of the display areas 1a, 1b are rotationally symmetric axes of the display areas 1a, 1b, and the optical axes EXa, EXb of the optical parts 120a, 120b are rotationally symmetric axes of the lens surfaces of the lens elements and the openings of the diaphragm elements, which will be described later. The coincidence of the optical axes also takes into consideration the bending of light rays by the cross dichroic prism 18. The image light ML1, ML2 emitted from each optical part 120a, 120b is superimposed and projected at the exit pupil EP, and is emitted as a synthesized image light ML.

[0018] The red display panel 11r is a first display panel and emits red image light MLr, which is a first image light. The display panel 11r is, for example, an organic EL (organic electro-luminescence) display, forms a still image or a moving image on a two-dimensional display surface 11d parallel to the XZ plane, and emits red image light MLr. The red display panel 11r includes a light-emitting element 14a and a transparent cover 14b. The light-emitting element 14a is a multiplicity of pixels arranged two-dimensionally along the XZ plane on a substrate, and each pixel has a structure similar to that of a general organic EL element, although not shown, and includes, in order from the substrate side, a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, and a transparent electrode layer.

[0019] In the illustrated example, the red display panel 11r divides the display surface 11d on which the light emitting elements 14a are arranged in the X direction, and has multiple, specifically, two display areas 1a and 1b. When viewed from the display surface 11d side on which the image is displayed, the display area 1a on the left side, i.e., the -X side, is the first display area, and the display area 1b on the right side, i.e., the +X side, is the second display area. The arrangement of the display areas 1a and 1b is not limited to an arrangement along the X direction, but may be arranged offset from the X direction. The display panel 11r has a horizontally elongated shape on the XZ plane based on the Z direction. The display areas 1a and 1b are obtained by dividing the horizontally elongated display surface 11d into two equal parts, and as a result, have vertically elongated shapes with approximately the same dimensions. The same image with the same dimensions is displayed in the display areas 1a and 1b. In other words, the display surface 11d is composed of one display panel 11r arranged in one place, but the same image exists on the -X side and the +X side with the YZ plane as the boundary. The aspect ratio (horizontal to vertical ratio) of the display surface 11d is, for example, 16:9, but can be changed as appropriate. In addition, the divided display areas 1a and 1b may be horizontally long, in which case the aspect ratio (horizontal to vertical ratio) of the display surface 11d is, for example, 32:9.

[0020] The blue display panel 11b is a second display panel, and emits blue image light MLb, which is the second image light. The display panel 11b is an organic EL display similar to the red display panel 11r, and forms a still image or a moving image on a two-dimensional display surface 11d parallel to the XZ plane, and emits blue image light MLb. The blue display panel 11b includes a light-emitting element 14a and a transparent cover 14b. The light-emitting element 14a incorporated in the blue display panel 11b has a similar structure to the light-emitting element 14a incorporated in the red display panel 11r, but has a different emission wavelength from the light-emitting element 14a of the red display panel 11r. That is, the blue image light MLb, which is the second image light, and the red image light MLr, which is the first image light, have different wavelength ranges.

[0021] In the illustrated example, the blue display panel 11b, like the red display panel 11r, divides the display surface 11d on which the light emitting elements 14a are arranged in the X direction, and has multiple, specifically, two display areas 1a and 1b. When viewed from the display surface 11d side on which the image is displayed, the display area 1a on the left side, i.e., the -X side, is the first display area, and the display area 1b on the right side, i.e., the +X side, is the second display area. The display panel 11b has a horizontally elongated shape on the XZ plane, based on the Z direction. The display areas 1a and 1b are obtained by equally dividing the horizontally elongated display surface 11d, and as a result, have vertically elongated shapes of approximately the same dimensions. The same image of the same dimensions is displayed in the display areas 1a and 1b.

[0022] The green display panel 11g is a third display panel and emits green image light MLg, which is the third image light. The display panel 11g is an organic EL display similar to the red display panel 11r and the blue display panel 11b, and forms a still image or a moving image on a two-dimensional display surface 11d parallel to the XY plane, and emits green image light MLg. The green display panel 11g includes a light-emitting element 14a and a transparent cover 14b. The light-emitting element 14a incorporated in the green display panel 11g has a similar structure to the light-emitting element 14a incorporated in the red display panel 11r and the blue display panel 11b, but has a different emission wavelength from the light-emitting element 14a of the red display panel 11r and the blue display panel 11b. That is, the green image light MLg, which is the third image light, has a different wavelength range from the red image light MLr, which is the first image light, and the blue image light MLb, which is the second image light.

[0023] In the illustrated example, the green display panel 11g, like the red display panel 11r, divides the display surface 11d on which the light emitting elements 14a are arranged in the X direction, and has multiple, specifically, two display areas 1a and 1b. When viewed from the display surface 11d side on which the image is displayed, the display area 1a on the left side, i.e., the -X side, is the first display area, and the display area 1b on the right side, i.e., the +X side, is the second display area. The display panel 11g has a horizontally elongated shape on the XY plane based on the Y direction. The display areas 1a and 1b are obtained by equally dividing the horizontally elongated display surface 11d, and as a result, have vertically elongated shapes of approximately the same dimensions. The same image of the same dimensions is displayed in the display areas 1a and 1b.

[0024] The light emitting element 14a incorporated in the display panels 11r, 11b, and 11g is an organic EL display with a first-order resonant cavity. Therefore, the orientation characteristics of the display panels 11r, 11b, and 11g are such that the light intensity is high in the front direction parallel to the optical axes DXa and DXb, and the light intensity drops rapidly in a direction slightly tilted from the front direction. The angle at which the light intensity is half-maximum is defined as the radiation angle, and the radiation angle from the pixel of the red image light MLr, the radiation angle from the pixel of the blue image light MLb, and the radiation angle from the pixel of the green image light MLg are within about 20°. Based on these radiation angles of the image lights MLr, MLb, and MLg, the dichroic mirrors 18r and 18b of the cross dichroic prism 18 described later are designed.

[0025] The cross dichroic prism 18 is a light combining member LC that combines the image lights MLr, MLb, and MLg emitted from the display panels 11r, 11b, and 11g. The cross dichroic prism 18 is a rectangular prism-shaped member, and has three light incident surfaces 18ia, 18ib, and 18ic and one light exit surface 18o as side surfaces of the rectangular prism. The opposing first light incident surface 18ib and second light incident surface 18ic extend parallel to each other, and the opposing third light incident surface 18ia and light exit surface 18o extend parallel to each other. The two opposing first light incident surface 18ib and second light incident surface 18ic extend perpendicular to the third light incident surface 18ia provided between them.

[0026] The transparent cover 14b of the red display panel 11r is fixed so as to be attached to the first light incident surface 18ib of the cross dichroic prism 18. The first red display panel 11r causes red image light MLr, which is the first image light, to enter the cross dichroic prism 18 from the first light incident surface 18ib. The transparent cover 14b of the blue display panel 11b is fixed so as to be attached to the second light incident surface 18ic of the cross dichroic prism 18. The blue display panel 11b causes blue image light MLb, which is the second image light, to enter the cross dichroic prism 18 from the second light incident surface 18ic. The transparent cover 14b of the green display panel 11g is fixed so as to be attached to the third light incident surface 18ia of the cross dichroic prism 18. The green display panel 11g causes green image light MLg, which is the third image light, to enter the cross dichroic prism 18 from a third light incident surface 18ia.

[0027] In the cross dichroic prism 18, the cross axis CX extends along the intersection line between the two dichroic mirrors 18r, 18b and is parallel to the X direction. The central axis AX passing through the light exit surface 18o of the cross dichroic prism 18 extends in a direction perpendicular to the light guide plate 51a, that is, in the Z direction. The central axis AX is an axis between the optical axis DXa of the display region 1a and the optical axis DXb of the display region 1b in the green display panel 11g facing the light exit surface 18o.

[0028] The cross dichroic prism 18 is formed by joining four right-angled triangular prisms 18a made of glass or the like so that their right-angled edges coincide with each other, and has a structure in which two dichroic mirrors 18r, 18b are embedded at the boundaries or joints of the four right-angled triangular prisms 18a, which are perpendicular to each other. One dichroic mirror 18r is disposed at an angle of 45° with the first light incident surface 18ib. The dichroic mirror 18r forms a surface that connects the diagonal corners of the square outline when viewed from the direction of the cross axis CX of the cross dichroic prism 18. The other dichroic mirror 18b is disposed at an angle of 45° with the second light incident surface 18ic. The dichroic mirror 18b forms a surface that connects the diagonal corners of the square outline when viewed from the direction of the cross axis CX of the cross dichroic prism 18.

[0029] The red image light MLr incident on the first light incident surface 18ib of the cross dichroic prism 18 from the red display panel 11r is reflected by the dichroic mirror 18r and bent toward the exit side, i.e., the projection optical system 20, and is emitted from the light exit surface 18o in the +Z direction to the outside. The blue image light MLb incident on the second light incident surface 18ic of the cross dichroic prism 18 from the blue display panel 11b is reflected by the dichroic mirror 18b and bent toward the exit side, i.e., the projection optical system 20, and is emitted from the light exit surface 18o in the +Z direction to the outside. The green image light MLg incident on the third light incident surface 18ia of the cross dichroic prism 18 from the green display panel 11g passes toward the projection optical system 20 without being reflected by the dichroic mirrors 18r and 18b, and is emitted from the light exit surface 18o in the +Z direction to the outside. That is, the cross dichroic prism 18 transmits the green image light MLg. As a result, the cross dichroic prism 18 synthesizes an image in which the red image light MLr, the green image light MLg, and the blue image light MLb are superimposed, and the image light ML is emitted as image light ML and can be incident on the projection optical system 20. The image lights MLr, MLb, and MLg of each color are synthesized by the cross dichroic prism 18 for each display area 1a and 1b. The synthesized image lights ML1 and ML2 are respectively emitted to the optical portions 120a and 120b corresponding to each display area 1a and 1b in the projection optical system 20.

[0030] The projection optical system 20 guides the image light ML1, ML2 from each of the display areas 1a, 1b to the light guide member 50. As described above, the projection optical system 20 has a plurality of optical parts 120a, 120b arranged in accordance with the arrangement direction of the plurality of display areas 1a, 1b. The arrangement direction of the display areas 1a, 1b is not limited to the arrangement of the display areas 1a, 1b in the X direction as shown in the figure, but may correspond to the arrangement of the display areas 1a, 1b. The number of optical parts 120a, 120b corresponds to the division number of the display areas 1a, 1b. The image light ML1, ML2 emitted from each optical part 120a, 120b is superimposed and projected at the exit pupil EP, and is emitted as a synthesized image light ML.

[0031] The projection optical system 20 may include optical elements such as a reflecting mirror in addition to one or more lens members made of resin or glass. The optical surfaces or lens surfaces of the optical elements constituting the projection optical system 20 may be any of spherical, aspherical, and free-form surfaces.

[0032] The optical parts 120a and 120b have, in order from the display panel 11r, 11b, and 11g side, a lens part 21 and an aperture part 22 as optical elements that collimate, i.e., parallelize, incident light. The lens part 21 has, in order from the display panel 11r, 11b, and 11g side, a first lens member 21a, a second lens member 21b, and a third lens member 21c. The optical parts 120a and 120b are integrally formed with the respective lens members 21a, 21b, and 21c. Each of the lens members 21a, 21b, and 21c has a rectangular outer shape.

[0033] The optical parts 120a and 120b have one lens element 2a to 2f in each of the lens members 21a, 21b, and 21c. That is, in each of the lens members 21a, 21b, and 21c, a plurality of lens elements, in this embodiment, two lens elements, are arranged in the arrangement direction of the display areas 1a and 1b, that is, the X direction. The number of lens elements in each of the lens members 21a, 21b, and 21c corresponds to the number of divisions of the display areas 1a and 1b. The lens elements 2a to 2f are supported by the support members 2x, 2y, and 2z in the lens members 21a, 21b, and 21c, and are parts having lens surfaces. The lens elements 2a, 2c, and 2e in the optical part 120a are the first lens elements, and the lens elements 2b, 2d, and 2f in the optical part 120b are the second lens elements. In other words, in each of lens members 21a, 21b, and 21c viewed from the emission direction, lens elements 2a, 2c, and 2e on the left side, i.e., on the -X side, are defined as first lens elements, and lens elements 2b, 2d, and 2f on the right side, i.e., on the +X side, are defined as second lens elements.

[0034] In optical portion 120a on the -X side, first lens member 21a has lens element 2a as a first lens element, second lens member 21b has lens element 2c, and third lens member 21c has lens element 2e. That is, optical portion 120a has one or more lens elements 2a, 2c, and 2e (three in this embodiment) in the direction of optical axis EXa of each optical portion 120a.

[0035] In optical portion 120b on the +X side, first lens member 21a has lens element 2b, second lens member 21b has lens element 2d, and third lens member 21c has lens element 2f as the second lens element. That is, optical portion 120b has one or more lens elements 2b, 2d, and 2f, three in this embodiment, in the direction of optical axis EXb of each optical portion 120b.

[0036] The diaphragm portion 22 is a diaphragm member 22a disposed on the exit side of each of the optical portions 120a and 120b. The optical portions 120a and 120b are integrally formed in the diaphragm member 22a. The diaphragm member 22a has a rectangular outer shape.

[0037] The optical parts 120a and 120b have one aperture element 3a and one aperture element 3b in the aperture member 22a. That is, in the aperture member 22a, a plurality of aperture elements, in this embodiment, two aperture elements, are arranged in the arrangement direction of the plurality of display areas 1a and 1b, that is, in the X direction. The number of aperture elements in the aperture member 22a corresponds to the number of divisions of the display areas 1a and 1b. The aperture elements 3a and 3b are openings formed in the plate member 3x in the aperture member 22a. The aperture element 3a in the optical part 120a is the first aperture element, and the aperture element 3b in the optical part 120b is the second aperture element. In other words, in the aperture member 22a as viewed from the emission direction, the aperture element 3a on the left side, i.e., on the -X side, is the first aperture element, and the aperture element 3b on the right side, i.e., on the +X side, is the second aperture element.

[0038] In the optical portion 120a on the -X side, the diaphragm member 22a has a diaphragm element 3a. That is, the optical portion 120a has one or more diaphragm elements 3a, one in this embodiment, in the direction of the optical axis EXa of each optical portion 120a.

[0039] In the optical portion 120b on the +X side, the diaphragm member 22a has a diaphragm element 3b. That is, the optical portion 120b has one or more diaphragm elements 3b, one in this embodiment, in the direction of the optical axis EXb of each optical portion 120b.

[0040] The outer size of lens elements 2a and 2b of first lens member 21a is larger than the outer size of lens elements 2c to 2f of second and third lens members 21b and 21c and diaphragm elements 3a and 3b of diaphragm member 22a.

[0041] The outer size of lens elements 2c and 2d of second lens member 21b is larger than the outer size of lens elements 2e and 2f of third lens member 21c and diaphragm elements 3a and 3b of diaphragm member 22a.

[0042] The outer size of lens elements 2e and 2f of third lens member 21c is larger than the outer size of diaphragm elements 3a and 3b of diaphragm member 22a.

[0043] In the above, the curvatures of the paired lens elements constituting the first to third lens members 21a to 21c may be the same or different. If the lens elements have different curvatures, it is necessary to adjust the size of the display areas 1a and 1b of the display surfaces 11d of the display panels 11r, 11b, and 11g, and to adjust the positional relationship and thickness of the first to third lens members 21a to 21c in the direction of the central axis AX, i.e., in the Z direction.

[0044] The outer size of diaphragm elements 3a and 3b of diaphragm member 22a is smaller than the outer size of lens elements 2a to 2f of first to third lens members 21a to 21c.

[0045] Image light ML emitted from a first display region (display region 1a) on the -X side of display panel 11g etc. passes through cross dichroic prism 18 and first lens elements (lens elements 2a, 2c, 2e) on the -X side of first to third lens members 21a to 21c, and then enters a first aperture element (aperture element 3a) on the -X side of aperture member 22a. Image light ML emitted from a second display region (display region 1b) on the +X side of display panel 11g etc. passes through cross dichroic prism 18 and second lens elements (lens elements 2b, 2d, 2f) on the +X side of first to third lens members 21a to 21c, and then enters a second aperture element (aperture element 3b) on the +X side of aperture member 22a.

[0046] In the above, the first to third lens members 21a to 21c may be subjected to a light shielding treatment, for example, on a part or all of the support members 2x, 2y, and 2z that support the lens elements 2a to 2f. In this case, stray light can be suppressed. A light shielding member for preventing stray light may be provided separately. Also, the holder 71 that fixes the first to third lens members 21a to 21c and the diaphragm member 22a of the projection optical system 20 may be subjected to a light shielding treatment.

[0047] A specific example of the dimensions of the optical system will be described below. The description will be based on the green display panel 11g, but the same applies to the red display panel 11r and the blue display panel 11b. The size of the display surface 11d of the display panels 11r, 11b, and 11g is, for example, 15 mm wide and 10 mm long, with the Y direction shown in FIG. 8 and the X direction being the vertical direction and the horizontal direction, respectively. The size of the dichroic prism 18 tends to be larger than the size of the display surface 11d. The size of the dichroic prism 18 is determined by the radiation angle from the edge of the display surface 11d and the thickness of the dichroic prism 18. For example, if the half angle of the radiation angle is 10° and the thickness of the dichroic prism 18 is 6 mm, the length of one side of the dichroic prism 18 needs to be increased by 6×tan(10°) mm or more. The diameter of the throttling elements 3a and 3b of the throttling member 22a is, for example, 1 mm, and the distance between the throttling elements 3a and 3b is, for example, 4 mm.

[0048] FIG. 9 is a ray diagram showing specific light rays of the optical system of the first display driving unit 102a in a side view. FIG. 10 is a ray diagram showing specific light rays of the optical system of the first display driving unit 102a in a plan view. In the illustrated example, the direction of the main light LL of the light emitting points of the display panels 11r, 11b, and 11g is tilted. For convenience of explanation, FIG. 9 and FIG. 10 show the green image light MLg emitted from the green display panel 11g. In FIG. 10, the light rays appear to be emitted from the same place in the center part of the display surface 11d, but the light emitting regions are different on the +X side and the -X side based on the central axis AX. As a method of tilting the main light LL, for example, a microlens array or a fine structure is provided between the light emitting element 14a and the light incident surfaces 18ib, 18ic, and 18ia of the cross dichroic prism 18. Also, a configuration in which the color filter of the organic EL or OLED is shifted to emit light obliquely may be used. By tilting the direction of the principal ray, it is possible to prevent the image of the first display area (display area 1a) on the -X side from passing through lens elements 2a, 2c, and 2e of first to third lens members 21a to 21c on the -X side and becoming stray light, thereby reducing the influence of stray light while improving the brightness.

[0049] The direction of the principal ray LL of the light emitting point of the display panels 11r, 11b, and 11g does not have to be inclined. For example, the principal ray LL may be a light ray that generally radiates and spreads in a Lambertian manner. In this case, the possibility that the light ray will be incident on the adjacent lens elements of the first to third lens members 21a to 21c increases, but stray light is prevented by using an aperture or the like.

[0050] Returning to FIG. 4, in the first light-guiding optical system 103a or the light-guiding member 50, the light-guiding plate 51a is a member formed from a parallel plate, and has a first total reflection surface 51i and a second total reflection surface 51o, which are a pair of flat surfaces extending in the XY plane.

[0051] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are formed on the second total reflection surface 51o of the light guide plate 51a. That is, the incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are arranged on the outside world side, i.e., the +Z side. The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are designed to function as a reflective diffraction grating that partially transmits outside light.

[0052] The incident diffraction layer 51b is an input diffractive optical element which is an incident portion DI, and folds back the image light ML emitted from the display panels 11r, 11b, and 11g of the image light generating device 10 shown in FIG. 5 and the like and incident via the lens portion 21 of the projection optical system 20 so as to propagate inside the light guide member 50. The image light ML collimated around the optical axes EXa and EXb (see FIG. 6) perpendicular to the light guide plate 51a is incident on the incident diffraction layer 51b. The incident diffraction layer 51b is formed of a diffraction pattern which extends linearly in the vertical Y direction and is periodically repeated in the horizontal X direction.

[0053] The pupil enlargement grating layer 51e is a pupil enlargement diffractive optical element that is a relay unit DE, and is provided on the -X side of the incident diffraction layer 51b, and bends the optical path of the image light ML that is guided into the light guide plate 51a and travels in the -X direction as a whole so that it travels in the -Y direction as a whole. In the example of this embodiment, the relay unit DE is an element that converts the propagation guide direction of the image light ML from the horizontal direction to the vertical direction. The pupil enlargement grating layer 51e does not substantially lose angular information of the image light ML in the left and right X direction and angular information of the image light ML in the up and down Y direction while switching the diffraction direction. The pupil enlargement grating layer 51e guides the image light ML guided from the incident diffraction layer 51b into the light guide plate 51a to the exit diffraction layer 51c, while enlarging the pupil of the exit diffraction layer 51c. More specifically, the pupil enlargement grating layer 51e is interposed between the incident diffraction layer 51b and the exit diffraction layer 51c, and divides the light while guiding the image light ML in a direction (-Y direction) intersecting the diffraction direction (-X direction) of the incident diffraction layer 51b, and has a role of expanding the width of the light in the horizontal direction. That is, the pupil enlargement grating layer 51e expands the pupil in the horizontal direction, which is the first direction. The pupil enlargement grating layer 51e is formed with a diffraction pattern that extends linearly in a diagonal DS1 direction parallel to the XY plane and repeats periodically in a DS2 direction parallel to the XY plane and perpendicular to the DS1 direction. The DS1 direction is a direction 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 pupil enlargement grating layer 51e matches the grating period in the X direction of the pattern formed in the incident diffraction layer 51b, and matches the grating period in the Y direction of the pattern formed in the exit diffraction layer 51c.

[0054] The exit diffraction layer 51c is an output diffractive optical element that is an exit portion DO, and divides the light beam while guiding the image light ML in the -Y direction, and has a role of expanding the light beam width in the vertical direction. That is, the exit diffraction layer 51c expands the pupil in the vertical direction, which is the second direction perpendicular to the first direction. As a result, the light beam width in the X direction and the Y direction of the image light ML incident on the pupil position PP shown in FIG. 2 has a spread corresponding to the exit diffraction layer 51c, and the pupil size in the vertical direction and the horizontal direction increases through the pupil expansion grating layer 51e, the exit diffraction layer 51c, etc. From the exit diffraction layer 51c, the image light ML that is collimated with the exit optical axis OX (see FIG. 2) perpendicular to the light guide plate 51a as the center is output. The image light ML output from the exit diffraction layer 51c is about ±25° with the exit optical axis OX as the reference. That is, the angle of view of the first virtual image display device 100A is about 50°. The emission diffraction layer 51c is formed with a diffraction pattern that extends linearly in the horizontal X direction and is periodically repeated in the vertical Y direction.

[0055] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are formed, for example, from a surface relief type diffraction element. The surface relief type diffraction element is formed by nanoimprinting, but is not limited to this, and can also be formed by etching the surface of the light guide plate 51a, or a diffraction element may be attached. The material of the diffraction grating is a nanoimprint material when it is produced by nanoimprinting, and is the same material as the light guide plate 51a when it is produced by etching. The material of the light guide plate 51a is, for example, glass, resin, etc.

[0056] The first embodiment of the virtual image display device 100A, 100B comprises display panels 11r, 11b, 11g that emit image light ML, a projection optical system 20 that emits the image light ML from the display panels 11r, 11b, 11g, and a light-guiding member 50 that guides the image light ML emitted from the projection optical system 20 to an emission section DO, where the display panels 11r, 11b, 11g have a plurality of display areas 1a, 1b, and the projection optical system 20 has a plurality of optical portions 120a, 120b that are arranged in accordance with the arrangement direction of the plurality of display areas 1a, 1b and guide the image light ML from each display area 1a, 1b to the light-guiding member 50, and the image light ML emitted from each optical portion 120a, 120b is projected in a superimposed manner at the exit pupil EP.

[0057] In the above virtual image display devices 100A and 100B, the luminance of the image light ML at the exit pupil EP can be improved by dividing the display panels 11r, 11b, and 11g into a plurality of display regions 1a and 1b, providing a plurality of lens elements 2a to 2f according to the number of divisions, and causing the light from the divided display regions 1a and 1b to enter the light guiding member 50. In addition, since there is no need to arrange a plurality of display panels in one place to improve the luminance, the device can be made smaller.

[0058] Second Embodiment Hereinafter, a virtual image display device according to a second embodiment of the present invention will be described. Note that the virtual image display device of the second embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of the common parts will be omitted.

[0059] FIG. 11 is a diagram for explaining a virtual image display device of the second embodiment. In this embodiment, the number of divisions of the display areas 1a to 1d is changed on the display surface 11d of the display panels 11r, 11b, and 11g. The number of divisions can be changed as appropriate. The number of display areas 1a to 1d obtained by dividing the display surface 11d is the same as the number of lens elements 2a to 2l and diaphragm elements 3a to 3d of the projection optical system 20. In the illustrated example, the display surface 11d of the display panels 11r, 11b, and 11g is divided into four. In this embodiment, the brightness can be improved by arranging a plurality of display areas 1a to 1d, and in the illustrated case, the brightness is four times as high. Increasing the number of divisions reduces the resolution, but the display surface 11d can be enlarged.

[0060] [Other matters] The above-described structure is merely an example, and various modifications can be made within the scope of achieving the same function.

[0061] As shown in Fig. 12, the division direction of the display surface 11d of the display panels 11r, 11b, and 11g or the arrangement direction of the display areas 1a and 1b is not limited to the X direction, but may be the Y direction. By dividing the display surface 11d in the Y direction, the image light ML can be guided while avoiding the center line existing at the center of the cross dichroic prism 18. This makes it possible to suppress the occurrence of uneven brightness in the center of the image. When the display surface 11d is divided in the Y direction, the size of the cross dichroic prism 18 may become large depending on the required viewing angle and aspect ratio, but there is an effect that the center line of the image becomes less visible.

[0062] As shown in FIG. 13, the size of the image displayed in the multiple display areas 1a and 1b of the display surface 11d does not need to be the same in all the display areas 1a and 1b, and may be different. When the lens elements 2a to 2f of each lens member 21a, 21b, and 21c are the same lens member, have the same lens shape, and are arranged in the same way, an image with a small viewing angle is superimposed on an image with a large viewing angle, and only a specified location can be brightened. Area AR1 in FIG. 13 is a diagram for explaining a modified example of the display surface 11d, etc. Area AR2 in FIG. 13 shows an image of an image seen by the eye EY. In area AR1, the symbol EXa indicates the optical axis of the lens elements 2a, 2c, and 2e, and the symbol EXb indicates the optical axis of the lens elements 2b, 2d, and 2f. In the example of area AR1, it is specified that the central part of the image is brightened, and the viewing angle of the first display area (display area 1a) of the display surface 11d is larger than the viewing angle of the second display area (display area 1b). In this case, the lens elements 2a to 2f of each lens member 21a, 21b, and 21c have the same curvature and positional relationship between the first lens element and the second lens element, and only the diameter size is different. If there is no stray light, the diameter size may be the same. As shown in area AR2, the center part of the image is bright because two images overlap, and the peripheral part is dark because it is a single image.

[0063] The virtual image display device 100A may omit the diaphragm member 22a. Moreover, the virtual image display device 100A may provide the light guide member 50 with something equivalent to the diaphragm member 22a. Moreover, a plurality of diaphragm members may be provided. For example, the diaphragm member may be provided in a portion where stray light is likely to occur, such as the light exit surface 18o of the cross dichroic prism 18 or the exit part DO of the light guide member 50.

[0064] The display panels 11r, 11b, and 11g are not limited to organic EL, and can be replaced with display devices using LED arrays, micro LED arrays, OLEDs (organic light emitting diodes), micro OLEDs, inorganic EL, laser arrays, quantum dot light emitting elements, etc.

[0065] The display panels 11r, 11b, and 11g are not limited to the self-luminous image light generating device 10, but may be displays 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, the display panels 11r, 11b, and 11g may be LCOS (Liquid crystal on silicon, LCoS is a registered trademark), digital micromirror devices (specifically, DLP, a registered trademark), laser beam scanning, and the like.

[0066] The light combining member LC may be a member in which two dichroic prisms are bonded together to combine light, instead of the cross dichroic prism 18. The light combining member LC may also be a member in which two dichroic mirrors are arranged side by side to combine light. Also, only one display panel for emitting three colors may be provided without providing the light combining member LC.

[0067] The number of lens members constituting the lens portion 21 is not limited to three, the first to third lens members 21a to 21c, and can be changed as appropriate.

[0068] The light-guiding member 50 is not limited to including the incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e, and for example, the pupil enlargement grating layer 51e may be omitted. In this case, the incident diffraction layer 51b guides the collimated image light ML into the light-guiding plate 51a and causes it to propagate laterally, and the exit diffraction layer 51c causes the image light ML propagating laterally in the light-guiding plate 51a to exit toward the inner pupil position PP.

[0069] The light-guiding member 50 may be provided with an incident diffraction layer 51b, an exit diffraction layer 51c, and a pupil enlargement grating layer 51e on the projection optical system 20 side, i.e., the -Z side, of the light-guiding plate 51a. In this case, the incident diffraction layer 51b and the exit diffraction layer 51c are transmissive diffraction elements, and the pupil enlargement grating layer 51e is a reflective diffraction element.

[0070] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil enlargement grating layer 51e are not limited to diffraction elements, and may be formed from volume holograms. The incident portion DI, the relay portion DE, and the exit portion DO are not limited to those that diffract the image light ML, and may be deflection branching portions that change the direction of the image light ML. As a specific example, the incident portion DI, the relay portion DE, and the exit portion DO may be dielectric multilayer mirrors or metal mirrors. The incident portion DI, the relay portion DE, and the exit portion DO are not limited to those that are made of a single layer, and may be those that are made by laminating multiple functional layers that are adapted to the wavelength, etc., of the image light ML.

[0071] A polarizing plate or a filter can be sandwiched between the transparent cover 14b of the display panel 11r, 11b, 11g and the light entrance surface 18ib, 18ic, 18ia of the cross dichroic prism 18. The polarizing plate may change the polarization axis for each image displayed in the display area 1a, 1b. In particular, in the case of a light guide member using a mirror, this leads to a reduction in stray light.

[0072] 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).

[0073] In a specific embodiment, the virtual image display device comprises a display panel that emits image light, a projection optical system that emits the image light from the display panel, and a light guiding member that guides the image light emitted from the projection optical system to an emission section, wherein the display panel has a plurality of display areas, and the projection optical system has a plurality of optical parts that are arranged in accordance with the arrangement direction of the plurality of display areas and guide the image light from each display area to the light guiding member, and the image light emitted from each optical part is superimposed and projected at the exit pupil.

[0074] In the virtual image display device, the display panel is divided into a plurality of display regions, a plurality of lens elements corresponding to the number of divisions are provided, and the light from the divided display regions is made incident on the light guide member, thereby improving the brightness of the image light at the exit pupil. In addition, since it is not necessary to arrange a plurality of display panels in one place to improve the brightness, the device can be made compact.

[0075] In a specific embodiment, the virtual image display device includes a first display panel that is a display panel that emits a first image light from the image light, a second display panel that emits a second image light having a different wavelength range from the first image light, a third display panel that emits a third image light having a different wavelength range from the first image light and the second image light, and a cross dichroic prism that combines the first image light, the second image light, and the third image light.

[0076] In a specific embodiment of the virtual image display device, the optical portions have one or more lens elements along an optical axis of each optical portion.

[0077] In a specific embodiment of the virtual image display device, the optical sections have a diaphragm element on the exit side of each optical section, which makes it easier to suppress the occurrence of stray light.

[0078] In a specific embodiment of the virtual image display device, the optical axis of the display area coincides with the optical axis of the corresponding optical portion.

[0079] In a specific embodiment of the virtual image display device, the light guide member includes a flat light guide plate, an incident diffraction layer provided in association with the light guide plate, and an exit diffraction layer provided in association with the light guide plate at a location different from the incident diffraction layer as an exit section. In this case, the light guide member can propagate image light from the incident diffraction layer to the exit diffraction layer while expanding the pupil.

[0080] In a specific embodiment, the optical unit comprises a display panel that emits image light, a projection optical system that emits the image light from the display panel, and a light-guiding member that guides the image light emitted from the projection optical system to an emission section, wherein the display panel has a plurality of display areas, and the projection optical system has a plurality of optical parts that are arranged in accordance with the arrangement direction of the plurality of display areas and guide the image light from each display area to the light-guiding member, and the image light emitted from each optical part is superimposed and projected at the exit pupil. [Explanation of symbols]

[0081] 1a to 1d: display area, 2a to 2l: lens elements, 3a to 3d: aperture elements, 10: image light generating device, 11: image light emitting unit, 11d: display surface, 11r, 11b, 11g: display panel, 14a: light emitting element, 14b: transparent cover, 18: cross dichroic prism, 18ia, 18ib, 18ic: light entrance surface, 18o: light exit surface, 18r, 18b: dichroic mirror, 20: projection optical system, 21: lens portion, 21a, 21b, 21c: lens member, 22: aperture portion, 22a: aperture member, 50: light guiding member, 51a: light guiding plate, 51b: incident diffraction layer, 51 c... exit diffraction layer, 51e... pupil enlargement grating layer, 71... holder, 88... drive circuit member, 90... 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, 120a, 120b... optical part, DI... entrance unit, DE... relay unit, DO... exit unit, DXa, DXb... optical axis, EP... exit pupil, EXa, EXb... optical axis, EY... eye, LC... light synthesis member, ML, ML1, ML2... image light, MLb... blue image light, MLg... green image light, MLr... red image light, PP... pupil position, US... wearer

Claims

1. A display panel that emits image light; a projection optical system that outputs the image light from the display panel; a light guiding member that guides the image light emitted from the projection optical system to an emission portion; Equipped with the display panel has a plurality of display areas; the projection optical system includes a plurality of optical portions that are aligned in a direction in which the plurality of display areas are arranged and that guide the image light from each of the display areas to the light guide member; The image light emitted from each optical portion is superimposed and projected at an exit pupil. Virtual image display device.

2. a first display panel that emits a first image light out of the image light; a second display panel that emits second image light having a wavelength range different from that of the first image light; a third display panel that emits third image light having a wavelength range different from those of the first image light and the second image light; a cross dichroic prism that combines the first image light, the second image light, and the third image light. The virtual image display device according to claim 1 .

3. The optical portions have one or more lens elements along the optical axis of each optical portion. The virtual image display device according to claim 1 .

4. The optical sections have a diaphragm element on the exit side of each optical section. The virtual image display device according to claim 1 .

5. The optical axis of the display area coincides with the optical axis of the corresponding optical portion. The virtual image display device according to claim 1 .

6. The light guide member includes a flat light guide plate, an incident diffraction layer provided in association with the light guide plate, and an exit diffraction layer provided as the exit portion in association with the light guide plate at a position different from the incident diffraction layer. The virtual image display device according to claim 1 .

7. A display panel that emits image light; a projection optical system that outputs the image light from the display panel; a light guiding member that guides the image light emitted from the projection optical system to an emission portion; Equipped with the display panel has a plurality of display areas; the projection optical system includes a plurality of optical portions that are aligned in a direction in which the plurality of display areas are arranged and that guide the image light from each of the display areas to the light guide member; The image light emitted from each optical portion is superimposed and projected at an exit pupil. Optical unit.

Images