Virtual image display device and optical unit

Abstract

The invention provides a virtual image display device and an optical unit, which realize miniaturization of the virtual image display device and improve light utilization efficiency. The present invention is provided with: a display panel (11a) that emits video light (ML); a projection optical system (20) that collimates the image light (ML) from the display panel (11a); and a light guide member (50) provided with: a light guide plate (51a) that guides the image light (ML); an incidence unit (DI) that causes the image light (ML) to be incident on the light guide plate (51a); a relay unit (DE) that guides the video light (ML) that has passed through the incidence unit (DI) and enlarges the pupil in a first direction; and an emission unit (DO) that guides the video light (ML) that has passed through the relay unit (DE), enlarges the pupil in a second direction perpendicular to the first direction, and emits the video light (ML) from the light guide plate (51a), an emission pupil (Lx) of the projection optical system (20) has a shape in which the vertical width (He) is greater than the horizontal width (We), and the incidence unit (DI) has a shape in which the vertical width (Hn) is greater than the horizontal width (Wn) in accordance with the shape of the emission pupil (Lx).

Description

Technical Field

[0001] The present invention relates to a virtual image display device and an optical unit capable of observing a virtual image. Background Art

[0002] As a display device capable of observing a virtual image, there is a display device comprising: a light guide member into which image light emitted from an image light generating device is incident; a first diffraction element disposed on the incident side of the light guide member; a second diffraction element disposed on the emission side of the light guide member; and a reflector disposed at an end of the incident side of the light guide member (Patent Document 1). In the device of Patent Document 1, the image light passing through the first diffraction element is reflected by the reflector and propagates within the light guide member, and the image light passing through the second diffraction element is emitted toward the eye.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-156995

[0004] In the display device of Patent Document 1, when the size of the image light generating device is reduced in order to miniaturize the device, the luminance efficiency may be reduced. Summary of the invention

[0005] A virtual image display device or optical unit according to one aspect of the present invention comprises: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; and a light-guiding component comprising: a light-guiding plate that guides the image light; an incident portion that causes the image light to be incident on the light-guiding plate; a relay portion that guides the image light that has passed through the incident portion and enlarges the pupil in a first direction; and an emission portion that guides the image light that has passed through the relay portion, enlarges the pupil in a second direction that is perpendicular to the first direction, and causes the image light to be emitted from the light-guiding plate, wherein the emission pupil of the projection optical system has a shape in which the longitudinal width is greater than the lateral width, and the incident portion has a shape in which the longitudinal width is greater than the lateral width corresponding to the shape of the emission pupil. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a plan view illustrating a wearing state of the HMD according to the first embodiment.

[0007] Figure 2 It is a side view for explaining the arrangement of the optical system constituting the virtual image display device.

[0008] Figure 3 It is a plan view for explaining the arrangement of the optical system constituting the virtual image display device.

[0009] Figure 4 This is a front view illustrating a light guiding optical system or a light guiding component.

[0010] Figure 51 is a schematic plan view for explaining the optical system of the first display drive unit.

[0011] Figure 6 1 is a schematic side view illustrating an optical system of a first display drive unit.

[0012] Figure 7 1 is a schematic perspective view for explaining the optical system of the first display drive unit.

[0013] Figure 8 It is a top view illustrating the display surface of the display panel.

[0014] Fig. 9 It is a schematic diagram for explaining the angle characteristics and the like of the first display driving unit.

[0015] Fig.10 1 is an optical path diagram for explaining a modified example of the optical system of the first display drive unit.

[0016] Fig.11 It is a schematic plan view for explaining the optical system in the second embodiment.

[0017] Fig.12 It is a schematic side view for explaining the optical system in the second embodiment.

[0018] Fig.13 It is a diagram for explaining examples and comparative examples of the optical system according to the second embodiment.

[0019] Fig.14 1 is a light path diagram showing an example of light rays in the optical system according to the second embodiment.

[0020] Description of symbols

[0021] 10: image light generating device; 11a, 11r, 11b, 11g: display panel; 18: cross-dichroic prism; 20: projection optical system; 21: lens element; 30: lens barrel; 50: light guide component; 51a: light guide plate; 51b: incident diffraction layer; 51c: emission diffraction layer; 51e: pupil magnification grating layer; 88: drive circuit component; 90: user terminal; 100: optical unit; 100A , 100B: virtual image display device; 100C: supporting device; 102a, 102b: display driving unit; 103a, 103b: light guiding optical system; AX: optical axis; CX: cross axis; DE: relay unit; DI: incident unit; DO: emission unit; EY: eye; Lx: emission pupil; ML: image light; PP: pupil position; Pr, Pg, Pb: sub-pixels; Px: pixel; US: wearer. DETAILED DESCRIPTION

[0022] [First embodiment]

[0023] Below, refer to Figure 1 to Figure 3 etc., a first embodiment of the virtual image display device of the present invention is described.

[0024] Figure 1 2 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 HMD to recognize a video image as a virtual image. Figure 1 In the above, X, Y, and Z are orthogonal coordinate systems, the +X direction corresponds to the horizontal direction in which the two eyes EY of the observer or wearer US wearing the HMD 200 are arranged, the +Y direction corresponds to the upward direction perpendicular to the horizontal direction in which the two eyes EY of the wearer US are arranged, and the +Z direction corresponds to the front direction or the front direction of the wearer US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0025] 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 support devices 100C in the shape of temples that support the virtual image display devices 100A and 100B, and a user terminal 90 as an information terminal. The first virtual image display device 100A functions as an HMD alone, and is composed of a first display drive unit 102a arranged at the top and a first light guide optical system 103a that covers the front of the eyes in the shape of a glasses lens. The second virtual image display device 100B also functions as an HMD alone, and is composed of a second display drive unit 102b arranged at the top and a second light guide optical system 103b that covers the front of the eyes in the shape of a glasses lens. The support device 100C is a wearing component worn 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 left and right, and a detailed description of the second virtual image display device 100B is omitted.

[0026] Figure 2 It is a side view specifically illustrating the first display drive unit 102 a and the first light guiding optical system 103 a of the first virtual image display device 100A. Figure 3 10 is a plan view specifically illustrating the first display drive unit 102 a and the first light guiding optical system 103 a . Figure 4 It is a front view mainly explaining the first light guiding optical system 103a.

[0027] Reference Figure 2 as well as Figure 3The first display driving unit 102a includes an image light generating device 10, a projection optical system 20, and a driving circuit component 88. The image light generating device 10 is an optical engine including a display panel 11a. The projection optical system 20 is a collimator including a plurality of lens elements 21. 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 as the light guiding component 50. Collimation refers to optically adjusting the diffused light to a parallel state through an optical element so that it becomes collimated light, i.e., parallel light. The driving circuit component 88 enables the display panel 11a to perform a display operation. In addition, in the first virtual image display device 100A, the optical device other than the driving circuit component 88 is referred to as an optical unit 100. The first virtual image display device 100A guides the image light ML to the eye EY of the wearer US so that the wearer US sees a virtual image.

[0028] Reference Figure 4 The first light guide optical system 103a is a light guide component 50 capable of color display, and extends substantially parallel to the XY plane. The first light guide optical system 103a includes a light guide plate 51a, an incident diffraction layer 51b, a pupil magnifying grating layer 51e, and an emission diffraction layer 51c. The incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnifying grating layer 51e diffract according to the wavelength of the image light ML. The incident diffraction layer 51b is an incident portion DI, which receives the image light from the first display driving unit 102a (refer to Figure 2 ) is guided into the light guide plate 51a and propagates in the lateral direction. The pupil enlargement grating layer 51e is a relay part DE, which enlarges the pupil size of the image light ML propagating in the lateral direction in the light guide plate 51a while propagating downward. The emission diffraction layer 51c is an emission part DO, which enlarges the pupil size of the image light ML propagating downward in the light guide plate 51a while transmitting the image light ML toward the eye EY (refer to FIG. 1 ). Figure 2 ) is located at the inner pupil position PP (refer to Figure 2 ) emits image light ML.

[0029] Figure 5 and Figure 6 1 and 2 are schematic top and side views for explaining the optical system of the first display drive unit 102 a . Figure 7 1 is a schematic stereoscopic diagram illustrating the optical system of the first display driving unit 102a. In the first display driving unit 102a, the image light generating device 10 includes only one display panel 11a. That is, the display panel 11a includes pixels of three colors, RGB, and in the display panel 11a, the pixels of each color are arranged two-dimensionally. The projection optical system 20 includes a plurality of lens elements 21. The display panel 11a and the projection optical system 20 are fixed in a state of being positioned relative to each other by the lens barrel 30. The lens barrel 30 is connected together with the drive circuit component 88 by a bracket 71 (see FIG. 1 ) which also serves as a cover. Figure 2 ) are supported in a state where they are positioned relative to each other and are fixed to the first light guiding optical system 103a.

[0030] The display panel 11a is a display element or display device that emits image light ML in order to form an image corresponding to the virtual image. Specifically, the display panel 11a is a display of various light-emitting element arrays such as OLED (organic light-emitting diode, Organic Light Emitting Diode), micro OLED, organic EL (organic electroluminescence, Organic Electro-Luminescence), inorganic EL, LED (light-emitting diode), and micro LED, and forms a static image or a dynamic image on a two-dimensional display surface 11d parallel to the XY plane. In addition, OLED is included in the organic EL element. The display panel 11a has a light-emitting element 14a. The light-emitting element 14a is formed by arranging a plurality of pixel elements in two dimensions along the XY plane on a substrate. In the case where the display panel 11a is an OLED display, each pixel element constituting the light-emitting element 14a has a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, and a transparent electrode layer in sequence from the substrate side.

[0031] The display panel 11a is not limited to a self-luminous image light generating device, but may be a display composed of other light modulating elements such as LCD, and an image is formed by illuminating the light modulating element with a light source such as a background. As the display panel 11a, LCOS (reflective liquid crystal, Liquid crystal on silicon, LCoS is a registered trademark), digital micromirror device (specifically, DLP: registered trademark), laser beam scanning, etc. may be used instead of LCD.

[0032] Figure 811 is a top view of the display surface 11d of the display panel 11a. The display surface 11d of the display panel 11a has a horizontally long shape in which the horizontal width Wp is larger than the vertical width Hp. Accordingly, the display panel 11a also has a horizontally long shape. In the present embodiment, the horizontal width Wp is the length in the horizontal or left-right direction, that is, the X direction, and the vertical width Hp is the length in the vertical or up-down direction, that is, the Y direction. The horizontal direction is the direction in which the positions of the eye EY are arranged and the direction in which the light guide plate 51a extends. The vertical direction is a direction perpendicular to the horizontal direction. In the case where the image light generating device 10 is composed of only one display panel 11a, for the sub-pixels Pr, Pg, and Pb of each color of RGB, the display panel 11a arranges the sub-pixels Pr, Pg, and Pb of RGB as one pixel Px (pixel element) in two dimensions. That is, the display panel 11a has a stripe structure of three colors through the sub-pixels Pr, Pg, and Pb. The sub-pixels Pr, Pg, and Pb have a vertically long shape. Therefore, the viewing angle characteristic of the display panel 11a is wider in the vertical direction, that is, in the Y direction. Here, the viewing angle characteristic refers to the property that the appearance of contrast, color, etc. is different depending on the direction (angle) of viewing the screen.

[0033] Fig. 9 Schematic diagram for explaining the angle characteristics of the first display driving unit 102a. Fig. 9 In the display panel 11a having the above-mentioned vertically long stripe structured pixel Px, the vertical angle of view of the image light ML emitted from the display panel 11a is larger than the horizontal angle in the vertical direction (see Figure 6 and Figure 8 ). Therefore, the amount of irradiated light beam at the exit pupil position of the projection optical system 20 can be increased, and the light utilization efficiency of the entire optical system can be improved. Here, the intake angle θ refers to the angle at which the projection optical system 20 can take in the image light ML emitted from the display panel 11a (the angle of the incident light relative to the optical axis AX of the projection optical system 20).

[0034] The projection optical system 20 includes a first lens 21a and a second lens 21b as a lens element 21 for collimating or parallelizing incident light. The projection optical system 20 has a function substantially equivalent to that of a single lens 20i, and collimates the image light ML emitted from the display surface 11d of the display panel 11a to a state having a predetermined light width, and emits it toward the incident diffraction layer 51b. In addition to one or more lens elements made of resin or glass, the projection optical system 20 may also include optical elements such as reflectors. The optical surface of the optical element constituting the projection optical system 20 may be any one of a spherical surface, an aspherical surface, and a free-form surface.

[0035] The light guide plate 51 a is a member formed of parallel flat plates, and has a pair of flat surfaces extending along the XY plane, namely, a first total reflection surface 51 i and a second total reflection surface 51 o .

[0036] return Figure 4 In the first light guide optical system 103a or the light guide member 50, the incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification 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 emission diffraction layer 51c, and the pupil magnification grating layer 51e are arranged on the external side of the light guide plate 51a, that is, the +Z side. The incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification grating layer 51e are designed to function as a reflective diffraction grating that partially transmits external light.

[0037] The incident diffraction layer 51b is an input diffraction optical element as the incident portion DI, and makes the image light ML emitted from the display panel 11a of the image light generating device 10 and incident via the lens element 21 of the projection optical system 20 bend back in a manner of propagating inside the light guide member 50. The incident diffraction layer 51b is incident on the optical axis AX (refer to FIG. 1 ) perpendicular to the light guide plate 51a. Figure 2 ) is the collimated image light ML centered at the incident diffraction layer 51b. The incident diffraction layer 51b is formed of a diffraction pattern that extends linearly in the longitudinal Y direction and is periodically repeated in the lateral X direction.

[0038] The pupil enlargement grating layer 51e is a pupil enlargement diffraction optical element as a relay part DE, and is arranged on the -X side of the incident diffraction layer 51b, so that the optical path is bent in a manner that the image light ML guided into the light guide plate 51a and traveling in the -X direction as a whole travels in the -Y direction as a whole. In the example of this embodiment, the relay part DE is an element that converts the propagation light guiding direction of the image light ML from the horizontal direction to the vertical direction. The pupil enlargement grating layer 51e changes the diffraction direction, and does not substantially damage the angle information of the image light ML related to the left and right X direction and the angle information of the image light ML related to the up and down Y direction. The pupil enlargement grating layer 51e guides the image light ML guided from the incident diffraction layer 51b to the light guide plate 51a to the emission diffraction layer 51c, and enlarges the pupil of the emission diffraction layer 51c. More specifically, the pupil enlargement grating layer 51e is interposed between the incident diffraction layer 51b and the emission diffraction layer 51c, and guides the image light ML in a direction (-Y direction) intersecting the diffraction direction (-X direction) of the incident diffraction layer 51b and splits the light, which has the effect of enlarging the lateral light width. That is, the pupil enlargement grating layer 51e enlarges the lateral pupil as the first direction. The pupil enlargement grating layer 51e is formed by a diffraction pattern that extends linearly in the DS1 direction parallel to the XY plane and inclined, and is periodically repeated in the DS2 direction parallel to the XY plane and perpendicular to the DS1 direction. The DS1 direction is a direction rotated 45° counterclockwise 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 and Y directions of the pattern formed in the pupil enlargement grating layer 51e is consistent with the grating period in the X direction of the pattern formed in the incident diffraction layer 51b, and is consistent with the grating period in the Y direction of the pattern formed in the output diffraction layer 51c.

[0039] The output diffraction layer 51c is an output diffraction optical element as the output portion DO, which guides the image light ML in the -Y direction and splits the light, and has the function of enlarging the longitudinal light width. That is, the output diffraction layer 51c enlarges the pupil in the second direction perpendicular to the first direction, that is, the longitudinal direction. As a result, the incident light Figure 2 The image light ML at the pupil position PP shown in FIG. 1 has a light width in the X and Y directions that is extended corresponding to the emission diffraction layer 51c. The pupil size increases in the longitudinal and lateral directions after passing through the pupil enlargement grating layer 51e, the emission diffraction layer 51c, etc. The light is emitted from the emission diffraction layer 51c with an emission optical axis OX (refer to FIG. 1 ) perpendicular to the light guide plate 51a. Figure 2 ) is the center of the collimated image light ML. The image light ML emitted from the emission diffraction layer 51c is about ±25° based on the emission optical axis OX. That is, the viewing angle of the first virtual image display device 100A is about 50°. The emission diffraction layer 51c is formed by a diffraction pattern that extends linearly in the horizontal X direction and is periodically repeated in the vertical Y direction.

[0040] The incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification grating layer 51e are formed, for example, by 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 light guide plate 51a, or may be pasted with a diffraction element. The material of the diffraction grating is a nanoimprint material when it is made by nanoimprinting, and is the same material as the light guide plate 51a when it is made by etching. The material of the light guide plate 51a is, for example, glass, resin, etc.

[0041] Below, refer to Figure 5 as well as Figure 6 , the shapes and sizes of the display panel 11a, the projection optical system 20, and the incident diffraction layer 51b are collectively described.

[0042] The display surface 11d of the display panel 11a has a horizontally long shape with a horizontal width Wd larger than a vertical width Hd corresponding to the exit pupil Lx. The sub-pixels Pr, Pg, and Pb of each color in the display panel 11a have a vertically long shape with a vertical width Hp larger than the horizontal width Wp corresponding to the exit pupil Lx (see Figure 8 ). That is, the field angle characteristic of the image light ML has an angle characteristic that is wider in the longitudinal direction than in the transverse direction, corresponding to the emission pupil Lx. This angle characteristic can be achieved by providing a vertically long sub-pixel in the display panel 11a, or by providing a vertically long lens in the lens element 21 as described later. The emission pupil Lx of the projection optical system 20 has a vertically long shape in which the vertical width He is larger than the transverse width We. The shape of the emission pupil Lx is the contour shape of the image light ML associated with the surface perpendicular to the optical axis AX. The shape of the emission pupil Lx is based on the projection optical system 20 in which the collimated image light ML overlaps the pupil position, and mainly depends on the light distribution characteristics of the pixels of the display panel 11a. In the case where there is an optical element that acts on the light distribution characteristics, it is affected by the optical element that acts on the characteristics, and is affected by the opening shape of the projection optical system 20 and the size of the display panel 11a. In addition, the lenses 21a and 21b of the lens element 21 have a vertically long shape in which the vertical width is larger than the transverse width, corresponding to the emission pupil Lx. That is, the lenses 21a and 21b have a longitudinally elongated shape. The incident diffraction layer 51b as the incident portion DI has a longitudinally elongated shape in which the longitudinal width Hn is larger than the transverse width Wn corresponding to the exit pupil Lx. The size of the incident diffraction layer 51b is the same as the size of the exit pupil Lx, but may be slightly larger than the size of the exit pupil Lx. Thus, in the incident diffraction layer 51b, the light loss of the image light ML from the projection optical system 20 can be reduced.

[0043] In order to miniaturize the projection optical system 20, it is necessary to reduce the incident diffraction layer 51b. Specifically, the horizontal width Wn of the incident diffraction layer 51b is, for example, about 1 mm, and the vertical width Hn is, for example, about 2 mm. The exit pupil Lx of the projection optical system 20 is, in a manner corresponding to the incident diffraction layer 51b, with a horizontal width We of, for example, about 1 mm, and a vertical width He of, for example, about 2 mm. Thus, the horizontal width of the projection optical system 20 can be reduced, and AR (augmented reality) glasses with a shape close to glasses can be realized.

[0044] In the above, when the incident diffraction layer 51b is long, it is preferred to first fold back in the short side direction of the incident diffraction layer 51b, that is, in the lateral direction, to guide the light. This is because when the light is guided by the light guide plate 51a, if it enters the incident diffraction layer 51b again, loss occurs.

[0045] The virtual image display device 100A, 100B of the first embodiment has: a display panel 11a, which emits image light ML; a projection optical system 20, which collimates the image light ML from the display panel 11a; and a light guiding component 50, which has: a light guiding plate 51a, which guides the image light ML; an incident portion DI, which makes the image light ML incident on the light guiding plate 51a; a relay portion DE, which guides the image light ML passing through the incident portion DI and enlarges the pupil in a first direction; and an emission portion DO, which guides the image light ML passing through the relay portion DE and enlarges the pupil in a second direction perpendicular to the first direction and causes the image light ML to be emitted from the light guiding plate 51a, the emission pupil Lx of the projection optical system 20 has a shape in which the longitudinal width He is greater than the lateral width We, and the incident portion DI has a shape in which the longitudinal width Hn is greater than the lateral width Wn corresponding to the shape of the emission pupil Lx.

[0046] In the above-mentioned virtual image display apparatuses 100A and 100B, the exit pupil Lx when irradiated to the light guide plate 51a through the projection optical system 20 is larger in the longitudinal direction than in the transverse direction, thereby reducing the transverse width of the projection optical system 20 and increasing the irradiation light beam amount. Thus, the virtual image display apparatuses 100A and 100B can be close to the shape of glasses by miniaturizing the projection optical system 20, and can improve the brightness of the light emitted from the light guide member 50 or the light guide plate 51a, thereby improving the light utilization efficiency.

[0047] Fig.10 1 is an optical path diagram for explaining a modified example of the optical system of the first display drive unit 102a. Fig.10 In FIG. 1 , area AR1 represents a cross section of the optical system of the first display drive unit 102 a, and area AR2 represents a longitudinal section of the optical system of the first display drive unit 102 a. Fig.10As shown, the optical system of the first display driving unit 102a in this embodiment is not limited to a telecentric optical system, but may be a non-telecentric optical system. However, according to conditions such as the field of view FOV and the panel size of the display panel 11a, the design of the telecentric optical system is optimal.

[0048] [Second embodiment]

[0049] 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 according to the second embodiment is obtained by partially modifying the virtual image display device according to the first embodiment, and description of the common parts will be omitted.

[0050] Fig.11 and Fig.12 10 is a schematic top view and side view for explaining the optical system of the first display driving unit 102a. In the first display driving unit 102a, the image light generating device 10 of the first display driving unit 102a includes three display panels 11r, 11b, 11g and a cross dichroic prism 18. The projection optical system 20 is a collimator including a plurality of lenses 21a and 21b as lens elements 21.

[0051] The red display panel 11r is a first display panel, and emits red image light MLr as first image light. The display panel 11r is, for example, a micro OLED display, and forms a static image or a dynamic image on a two-dimensional display surface 11d parallel to the YZ plane, and emits red image light MLr.

[0052] The blue display panel 11b is the second display panel, and emits blue image light MLb as the second image light. The display panel 11b is, for example, a micro OLED display similar to the red display panel 11r, and forms a static image or a dynamic image on a two-dimensional display surface 11d parallel to the YZ plane, and emits blue image light MLb. The light emitting element 14a assembled in the blue display panel 11b and the light emitting element 14a of the red display panel 11r have different emission wavelengths. That is, the blue image light MLb as the second image light and the red image light MLr as the first image light have different wavelength bands.

[0053] The green display panel 11g is a third display panel, and emits green image light MLg as the third image light. The display panel 11g is, for example, a micro OLED display similar to the red display panel 11r, and forms a static image or a dynamic image on a two-dimensional display surface 11d parallel to the XY plane, and emits green image light MLg. The light emitting element 14a assembled in the green display panel 11g has a different light emission wavelength from the light emitting element 14a of the red and blue display panels 11r and 11b. That is, the green image light MLg as the third image light has a different wavelength band from the red image light MLr as the first image light and the blue image light MLb as the second image light.

[0054] The light emitting elements 14a assembled in the display panels 11r, 11b, and 11g are all micro OLED displays provided with a primary resonance type cavity. Therefore, the orientation characteristics of the display panels 11r, 11b, and 11g are that the light intensity is large in the front direction parallel to the optical axis AX, and the light intensity decreases rapidly in the direction slightly inclined relative to the front direction. The angle at which the light intensity is half the value is taken as the radiation angle, and the radiation angle of the red image light MLr from the pixel, the radiation angle of the blue image light MLb from the pixel, and the radiation angle of the green image light MLg from the pixel are within about 20°. Based on the radiation angles of these image lights MLr, MLb, and MLg, the dichroic mirrors 18r and 18b of the cross dichroic prism 18 described later are designed.

[0055] The display panel 11r for red is fixed in a manner of being attached to the first light incident surface 18ib of the cross dichroic prism 18. The first display panel 11r for red allows red image light MLr, which is a first image light, to enter the cross dichroic prism 18 from the first light incident surface 18ib. The display panel 11b for blue is fixed in a manner of being attached to the second light incident surface 18ic of the cross dichroic prism 18. The second display panel 11b for blue allows blue image light MLb, which is a second image light, to enter the cross dichroic prism 18 from the second light incident surface 18ic. The display panel 11g for green is fixed in a manner of being attached to the third light incident surface 18ia of the cross dichroic prism 18. The third display panel 11g for green allows green image light MLg, which is a third image light, to enter the cross dichroic prism 18 from the third light incident surface 18ia.

[0056] The cross dichroic prism 18 is formed by joining four right-angled triangular prisms formed of glass materials or the like in a manner that the right-angled edges are consistent, and has a structure in which two perpendicular dichroic mirrors 18r and 18b are embedded in their joints. The dichroic mirror 18r on one side is arranged to form an angle of 45° with the first light incident surface 18ib. The dichroic mirror 18r forms a surface that connects the diagonals of the square outline when viewed from the direction of the cross axis CX of the cross dichroic prism 18. The dichroic mirror 18b on the other side is arranged to form an angle of 45° with the second light incident surface 18ic. The dichroic mirror 18b forms a surface that connects the diagonals of the square outline when viewed from the direction of the cross axis CX of the cross dichroic prism 18.

[0057] The red image light MLr incident on the first light incident surface 18ib of the cross dichroic prism 18 from the first display panel 11r for red is reflected by the dichroic mirror 18r and bent toward the projection optical system 20 on the emission side, and is emitted from the light emission 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 second display panel 11b for blue is reflected by the dichroic mirror 18b and bent toward the projection optical system 20 on the emission side, and is emitted from the light emission 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 third display panel 11g for green is not reflected by the dichroic mirrors 18r and 18b, but passes toward the projection optical system 20, and is emitted from the light emission surface 18o in the +Z direction to the outside. That is, the cross dichroic prism 18 allows the green image light MLg to pass through. As a result, the cross dichroic prism 18 can synthesize an image in which the red image light MLr, the green image light MLg, and the blue image light MLb overlap each other, emit the image light ML, and enter the projection optical system 20 .

[0058] In the cross dichroic prism 18, the cross axis CX extends along the intersection of the two dichroic mirrors 18r and 18b and is parallel to the Y direction. The optical axis AX passing through the light exit surface 18o of the cross dichroic prism 18 extends in the Z direction which is perpendicular to the light guide plate 51a.

[0059] The projection optical system 20 is an optical system that is substantially telecentric with respect to the display panels 11r, 11b, 11g as the object side. That is, the principal light rays of the image light emitted from the display surface 11d of each display panel 11r, 11b, 11g, that is, each part of the light emitting element 14a, pass through the light incident surfaces 18ib, 18ic, 18ia of the cross dichroic prism 18 in a state substantially parallel to the optical axis AX, and are incident on the cross dichroic prism 18, and are emitted from the cross dichroic prism 18 substantially parallel to the optical axis AX. Thus, the red image light MLr, the green image light MLg, and the blue image light MLb are incident on the dichroic mirrors 18r, 18b within a predetermined angle range, and the light loss caused by the dichroic mirrors 18r, 18b can be suppressed.

[0060] In addition, the arrangement of the display panels 11r, 11b, and 11g can be changed appropriately.

[0061] The angular characteristics of the dichroic mirrors 18r and 18b widen correspondingly with the long side of the exit pupil Lx or the incident diffraction layer 51b. The cross axis CX of the dichroic mirrors 18r and 18b is along the longitudinal direction of the light guide component 50 or the light guide plate 51a. In the cross dichroic prism 18, the traveling direction of the image light ML before being bent by the dichroic mirrors 18r and 18b is consistent with the transverse direction of the incident diffraction layer 51b. In other words, the length of the traveling direction of the image light ML before being bent by the dichroic mirrors 18r and 18b corresponds to the transverse width Wn of the incident diffraction layer 51b. When installed, the short side direction of the incident diffraction layer 51b becomes the horizontal direction.

[0062] In the optical system that synthesizes light by a plurality of display panels 11r, 11b, 11g and dichroic mirrors 18r, 18b, since each panel uses a monochromatic light source, the light-emitting layer can be set to a monochromatic structure, unlike the optical system that displays three colors by one panel. In addition, since the optical system that synthesizes light does not have a reduction in the amount of light caused by the color filter, it is possible to achieve high brightness. Even an optical system with low brightness efficiency, such as an optical system that uses a pupil-enlarging light guide plate with a diffraction element as in the present embodiment, can output practical brightness, so it is effective. The cross dichroic prism 18 used for three-color synthesis has the characteristics of reflection and transmission in different wavelength bands in each color of RGB as the characteristics of the dichroic mirrors 18r, 18b. Generally, the reflection and transmission characteristics are offset from the wavelength characteristics according to the angle of the light incident on the dichroic mirrors 18r, 18b. Therefore, for a light source with a wide range of light such as an organic light emitting diode, it is necessary to limit the incident angle to a certain extent. For example, in the red reflecting dichroic mirror 18r, the switching region of transmission and reflection (specifically, the switching region of green transmission and red reflection) needs to be within the range of 550nm to 630nm in the entire angle range. For example, in the blue reflecting dichroic mirror 18b, the switching region of transmission and reflection (specifically, the switching region of blue reflection and green transmission) needs to be within the range of 470nm to 530nm in the entire angle range. In order to meet this condition, the condition of the incident angle of the red image light MLr or the blue image light MLb to the dichroic mirrors 18r and 18b needs to be less than ±7° with respect to the tilt angle of the dichroic mirrors 18r and 18b.

[0063] like Fig. 9 As shown, when the field of view of the projection optical system 20 is FOV, the exit pupil size is EPD, the panel size is D, the focal length of the projection optical system 20 is f, and the intake angle (half angle) of the light emitted from the display panel 11a is θ, the following relationship holds. In addition, the panel size D is the size of the display surface 11d of the display panel 11a.

[0064] f=EPD / 2tanθ

[0065] f=D / 2tan(FOV / 2)

[0066] tan(FOV / 2)=Dtanθ / EPD

[0067] According to the above relationship, when there is a limit on the swallowing angle θ, it is necessary to increase the panel size D or reduce the exit pupil size EPD. If the panel size D is increased, the size of the cross dichroic prism 18 as a synthetic prism also increases, so the projection optical system 20 as a whole becomes larger. In this case, it is necessary to configure the projection optical system 20 in a manner that does not interfere with the face of the wearer US, and the horizontal width of the first virtual image display device 100A becomes larger, resulting in deviation from the design of the HMD 200, increased weight, and other effects. In addition, when the exit pupil size EPD is reduced, although the projection optical system 20 can be reduced, the amount of irradiated light beams at the exit pupil position becomes smaller, and the brightness of the optical system is reduced.

[0068] Based on the above, in order to take into account both the glasses shape design and the brightness efficiency of HMD200, it is necessary to increase the exit pupil Lx while maintaining the horizontal width of the display panels 11r, 11b, 11g and the horizontal width of the projection optical system 20. As mentioned above, the cross dichroic prism 18 has a restriction on the incident angle, with a reflection angle of 45° as the basic. That is, the main ray angle of each viewing angle is based on the normal direction of the panel. In addition, basically parallel light is incident on the light guide plate 51a, so the projection optical system 20 is incident as a single-sided telecentric optical system. In order to realize the above structure, the vertical width He of the exit pupil Lx is made larger than the horizontal width We, and the vertical width Hn of the incident diffraction layer 51b of the light guide plate 51a is made larger than the horizontal width Wn.

[0069] like Fig.11 and Fig.12 As shown, the display surface 11d of the display panel 11g has a horizontally long shape in which the horizontal width Wd is larger than the vertical width Hd. In the present embodiment, the vertical width Hd and the horizontal width Wd of the display surface 11d of the display panel 11g are based on the third display panel 11g for green arranged opposite to the light guide component 50. The shapes of the first display panel 11r for red and the second display panel 11b for blue are set to be the same as the third display panel 11g for green. The dichroic mirrors 18r and 18b are arranged in a manner inclined 45° in the horizontal direction relative to the optical axis AX. The allowable range of the incident angle to the dichroic mirrors 18r and 18b is less than 45±7° in the medium of the cross dichroic prism 18. The projection optical system 20 is designed to be unilaterally telecentric. The main light emitted from the display panels 11r, 11b, and 11g is perpendicular to the display surface 11d of the display panels 11r, 11b, and 11g. Here, when the incident angle exceeds 45±7°, light that should be reflected or transmitted is not reflected or transmitted at a certain wavelength, and the color changes and the brightness decreases significantly in the periphery of the exit pupil Lx of the projection optical system 20 .

[0070] Here, if the lateral field of view angle is large, the size of the cross dichroic prism 18 becomes large, which also has a great influence on the size of the projection optical system 20 itself. Therefore, by increasing the exit pupil Lx in the longitudinal direction in a manner such that the longitudinal field of view angle FOV is used larger than the lateral field of view angle, it is possible to suppress the enlargement of the cross dichroic prism 18, reduce the back focus of the projection optical system 20, and reduce the size of the projection optical system 20.

[0071] Fig.13 1 is a diagram for explaining a design example of an output pupil size EPD when the incident angle to the dichroic mirrors 18r and 18b in the cross dichroic prism 18 needs to be suppressed to ±7°. Fig.13 , a calculation example is shown for comparing the difference in size between the output pupil Lx of the embodiment having a longitudinally long elliptical shape and the output pupil Lx of the comparative example having a perfect circular shape. The panel size D is set to 0.3 inches, and the field of view angle FOV is set to 60°. According to the calculation result, by setting the shape of the output pupil Lx to a longitudinally long elliptical shape, the lateral size of the cross-dichroic prism 18 can be reduced from 10.2 mm to 9.6 mm. Thus, it is possible to achieve lightweighting due to the miniaturization of the prism size, and by shortening the distance to the lens element 21, it is also possible to reduce the size of the projection optical system 20.

[0072] Fig.14 : is a light path diagram showing an example of specific light rays of the optical system of the first display drive unit 102a in this embodiment. Fig.14 In the figure, region BR1 represents the cross section of the optical system of the first display drive unit 102a, and region BR2 represents the longitudinal section of the optical system of the first display drive unit 102a. The aspect ratio of the lenses 21a and 21b of the projection optical system 20 varies according to conditions such as the field of view angle FOV and the panel size D of the display panel 11a. For example, according to conditions such as the field of view angle FOV and the panel size D of the display panel 11a, the aspect ratio of the second lens 21a on the display panel 11a side is sometimes roughly the same. In addition, the optical system using the cross color separation prism 18 can also be in a non-telecentric state tilted inward according to design conditions such as the panel size D and the field of view angle FOV, and the allowable conditions for the incident angle of the light beam based on the design of the color separation mirrors 18r and 18b. As a result, the cross color separation prism 18 can also be made into a more miniaturized structure.

[0073] [Other matters]

[0074] The above-described structure is an example, and various changes can be made within the range in which the same function can be achieved.

[0075] The light guide member 50 may also be a member formed by overlapping a plurality of light guides in parallel. In this case, each light guide of the constituent elements may correspond to three colors, RBG, for example. Each light guide includes a light guide plate 51a, an incident diffraction layer 51b, an emission diffraction layer 51c, and a pupil enlargement grating layer 51e.

[0076] The incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification grating layer 51e are not limited to diffraction elements, but may also be formed by volume hologram elements. In addition, the incident portion DI, the relay portion DE, and the emission portion DO are not limited to diffracting the image light ML, but may also be deflection branch portions that change the direction of the image light ML. In a specific example, the incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification grating layer 51e may also be a dielectric multilayer film mirror or a metal mirror. The incident diffraction layer 51b, the emission diffraction layer 51c, and the pupil magnification grating layer 51e are not limited to being composed of a single layer, but may also be a stack of multiple functional layers suitable for the wavelength of the image light ML.

[0077] The incident diffraction layer 51b, the outgoing diffraction layer 51c, and the pupil enlargement grating layer 51e may also be formed on the first total reflection surface 51i of the light guide plate 51a. In this case, the incident diffraction layer 51b, the outgoing diffraction layer 51c, and the pupil enlargement grating layer 51e are designed to function as a transmission type diffraction grating.

[0078] As described above, the virtual image display devices 100A and 100B can be used as HMDs, but the present invention is not limited thereto and can be applied to various optical devices. For example, the present invention can also be applied to a head-up display (HUD).

[0079] A specific form of a virtual image display device comprises: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; and a light guiding component, which comprises: a light guiding plate that guides the image light; an incident portion that causes the image light to be incident on the light guiding plate; a relay portion that guides the image light that has passed through the incident portion and enlarges the pupil in a first direction; and an emission portion that guides the image light that has passed through the relay portion, enlarges the pupil in a second direction that is perpendicular to the first direction, and emits the image light from the light guiding plate, wherein the emission pupil of the projection optical system has a shape in which the longitudinal width is greater than the lateral width, and the incident portion has a shape in which the longitudinal width is greater than the lateral width corresponding to the shape of the emission pupil.

[0080] In the above virtual image display device, the exit pupil when irradiated to the light guide plate through the projection optical system is larger in the longitudinal direction than in the transverse direction, thereby reducing the transverse width of the projection optical system and increasing the amount of irradiated light beam. As a result, the virtual image display device can be close to the shape of glasses by miniaturizing the projection optical system, and the brightness of the light emitted from the light guide component or the light guide plate is increased, thereby improving the light utilization efficiency.

[0081] In a specific embodiment of the virtual image display device, the first direction is the horizontal direction, the second direction is the vertical direction, the vertical width is the size in the second direction, and the horizontal width is the size in the first direction. When the incident portion has a vertically long shape, the light is initially guided by folding back in the horizontal direction of the short side of the incident portion, thereby suppressing the loss of the guided light.

[0082] In a specific embodiment of the virtual image display device, the incident portion, the emitting portion, and the relay portion are formed by any one of a diffraction element, a volume hologram element, a dielectric multilayer film reflective mirror, and a metal reflective mirror.

[0083] In a virtual image display device in a specific embodiment, the viewing angle characteristics of the image light emitted from the display panel have an angle characteristic that is wider in the vertical direction than in the horizontal direction, corresponding to the exit pupil.

[0084] In a specific embodiment of the virtual image display device, the projection optical system includes a lens having a shape whose vertical width is larger than its horizontal width corresponding to the exit pupil. In this case, the size of the projection optical system can be reduced.

[0085] In a specific embodiment of the virtual image display device, the sub-pixel of each color in the display panel has a shape with a vertical width greater than a horizontal width corresponding to the exit pupil. In this case, the viewing angle characteristic of the display panel becomes wider in the vertical direction.

[0086] In a specific embodiment, a virtual image display device includes: a first display panel that emits a first image light among image lights; a second display panel that emits a second image light having a wavelength band different from that of the first image light; a third display panel that emits a third image light having a wavelength band different from that of the first image light and the second image light; and a cross dichroic prism that synthesizes the first image light, the second image light, and the third image light. In this way, by synthesizing the first image light, the second image light, and the third image light, a high-brightness virtual image can be displayed.

[0087] In a specific form of a virtual image display device, the angular characteristics of the dichroic mirror of the cross dichroic prism widen correspondingly with the long side of the exit pupil, the cross axis of the dichroic mirror is along the longitudinal direction of the light guiding component, and in the cross dichroic prism, the length of the traveling direction of the image light before being bent by the dichroic mirror corresponds to the lateral width of the incident part.

[0088] In a specific embodiment of the virtual image display device, the display panel is any one of an organic EL display, a micro LED display, a reflective liquid crystal display, and a digital micromirror device.

[0089] The optical unit in a specific embodiment comprises: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; and a light guiding component, which comprises: a light guide plate that guides the image light; an incident portion that causes the image light to be incident on the light guide plate; a relay portion that guides the image light that has passed through the incident portion and enlarges the pupil in a first direction; and an emission portion that guides the image light that has passed through the relay portion, enlarges the pupil in a second direction perpendicular to the first direction, and emits the image light from the light guide plate, the emission pupil of the projection optical system having a shape in which the longitudinal width is greater than the lateral width, and the incident portion has a shape in which the longitudinal width is greater than the lateral width corresponding to the shape of the emission pupil.

Claims

1. A virtual image display device, comprising: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; and The light guide component comprises: a light guide plate that guides the image light; an incident portion that allows the image light to be incident on the light guide plate; a relay portion that guides the image light that has passed through the incident portion and enlarges the pupil in a first direction; and an emission portion that guides the image light that has passed through the relay portion, enlarges the pupil in a second direction perpendicular to the first direction, and causes the image light to be emitted from the light guide plate. The exit pupil of the projection optical system has a shape in which the vertical width is greater than the horizontal width. The incident portion has a shape in which the vertical width is greater than the horizontal width, corresponding to the shape of the exit pupil.

2. The virtual image display device according to claim 1, wherein: The first direction is the horizontal direction, the second direction is the vertical direction, The vertical width is the size in the second direction, and the horizontal width is the size in the first direction.

3. The virtual image display device according to claim 1, wherein: The incident portion, the emitting portion, and the relay portion are formed by any one of a diffraction element, a volume hologram element, a dielectric multilayer film reflective mirror, and a metal reflective mirror.

4. The virtual image display device according to claim 1, wherein: The viewing angle characteristic of the image light emitted from the display panel has an angle characteristic that is wider in the vertical direction than in the horizontal direction, corresponding to the exit pupil.

5. The virtual image display device according to claim 1, wherein: The projection optical system includes a lens having a shape in which the vertical width is greater than the horizontal width corresponding to the exit pupil.

6. The virtual image display device according to claim 1, wherein: The sub-pixel of each color in the display panel has a shape whose vertical width is greater than its horizontal width corresponding to the exit pupil.

7. The virtual image display device according to claim 1, wherein: The virtual image display device comprises: A first display panel, which is the display panel that emits a first image light among the image lights; A second display panel emitting a second image light having a wavelength band different from that of the first image light; A third display panel that emits a third image light having a wavelength band different from that of the first image light and the second image light; and A cross dichroic prism is used to synthesize the first image light, the second image light and the third image light.

8. The virtual image display device according to claim 7, wherein: The angular characteristic of the dichroic mirror of the cross dichroic prism becomes wider in accordance with the long side of the exit pupil. The cross axis of the dichroic mirror is along the longitudinal direction of the light guide component. In the cross dichroic prism, the length of the image light in the traveling direction before being bent by the dichroic mirror corresponds to the lateral width of the incident portion.

9. The virtual image display device according to claim 1, wherein: The display panel is any one of an organic EL display, a micro LED display, a reflective liquid crystal display and a digital micromirror device.

10. An optical unit comprising: a display panel that emits image light; a projection optical system that collimates the image light from the display panel; and The light guide component comprises: a light guide plate that guides the image light; an incident portion that allows the image light to be incident on the light guide plate; a relay portion that guides the image light that has passed through the incident portion and enlarges the pupil in a first direction; and an emission portion that guides the image light that has passed through the relay portion, enlarges the pupil in a second direction perpendicular to the first direction, and causes the image light to be emitted from the light guide plate. The exit pupil of the projection optical system has a shape in which the vertical width is greater than the horizontal width. The incident portion has a shape in which the vertical width is greater than the horizontal width, corresponding to the shape of the exit pupil.

Images