Virtual image display device and optical unit

Abstract

To improve the light utilization efficiency and image quality of a virtual image display device.SOLUTION: A virtual image display device 100A comprises a display panel 11a that emits video light ML, a polarization diffraction lens 21 that collimates the video light ML from the display panel 11a and has a different focal distance for each wave length; and a plurality of light guide members 51, 52, 53 that correspond to the wavelengths. The plurality of light guide members 51, 52, 53 respectively have light guide plates 51a, 52a, 53a that guide the video light ML, input diffraction optical elements DI that cause the light guide plates 51a, 52a, 53a to make the video light ML incident, and output diffraction optical elements DO that cause the light guide plates 51a, 52a, 53a to emit the video light ML.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] One virtual image display device includes an image projection unit that emits image light and a light guide plate that propagates the image light emitted by the image projection unit to the wearer's eyes (Patent Document 1). The light guide plate has a light diffraction unit that diffracts incident light. The light diffraction unit has multiple holograms formed at different angles relative to the incident surface of the light guide plate, and when a certain parallel light beam is incident, different wavelengths are diffracted by the multiple holograms. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-33047 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device of Patent Document 1, when RGB light emitted from the image projection unit is incident on the light guide plate, the pupil position becomes approximately the same for all RGB wavelengths due to the action of the same lens that constitutes the image projection unit. If the light guide plate is made up of multiple plates to accommodate RGB light, the utilization efficiency of the RGB light changes, which causes color unevenness and deteriorates image quality. [Means for solving the problem]

[0005] A virtual image display device or optical unit in one aspect of the present invention includes a display panel that emits image light, a polarized diffractive lens that collimates the image light from the display panel and has a different focal length for each wavelength, and a plurality of light-guiding members corresponding to the wavelengths, each of which has a light-guiding plate that guides the image light, an input diffractive optical element that causes the image light to enter the light-guiding plate, and an output diffractive optical element that causes the image light to emit from the light-guiding plate. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view illustrating a state in which an HMD according to a first embodiment is worn. [Figure 2] FIG. 2 is a side view illustrating the arrangement of an optical system that constitutes the virtual image display device. [Figure 3] FIG. 2 is a plan view illustrating the arrangement of an optical system that constitutes the virtual image display device. [Figure 4] FIG. 2 is a cross-sectional view illustrating an optical system that constitutes the virtual image display device. [Figure 5] FIG. 4 is a rear view mainly illustrating the first light guiding optical system. [Figure 6] FIG. 10 is a conceptual diagram illustrating an optical system in a second embodiment. [Figure 7] FIG. 10 is a conceptual diagram illustrating an optical system according to a third embodiment. [Figure 8] FIG. 10 is a conceptual diagram illustrating an optical system according to a fourth embodiment. [Figure 9] FIG. 10 is a conceptual diagram illustrating an optical system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0008] FIG. 1 is a diagram illustrating a wearing state of a head-mounted display device (hereinafter also referred to as a head-mounted display or HMD) 200. The HMD 200 allows an observer or wearer US wearing the device to recognize an image as a virtual image. In FIG. 1 and other figures, X, Y, and Z are Cartesian coordinate systems, with the +X direction corresponding to the lateral direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are aligned, the +Y direction corresponding to the upward direction perpendicular to the lateral direction in which the eyes EY are aligned for the wearer US, and the +Z direction corresponding to the forward or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a first virtual image display device 100A for the right eye, a second virtual image display device 100B for the left eye, a pair of temple-shaped support devices 100C that support the virtual image display devices 100A and 100B, and a user terminal 90, which is an information terminal. The first virtual image display device 100A functions independently as an HMD and is composed of a first display driver 102a disposed at the top and a first light guiding optical system 103a that has the shape of a pair of eyeglass lenses and covers the front of the eyes. The second virtual image display device 100B similarly functions independently as an HMD and is composed of a second display driver 102b disposed at the top and a second light guiding optical system 103b that has the shape of a pair of eyeglass lenses and covers the front of the eyes. The HMD 200, which combines the first virtual image display device 100A and the second virtual image display device 100B, can also be considered a virtual image display device in a broad sense. 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 a pair of light guiding optical systems 103a, 103b via display driving units 102a, 102b that appear integrated in appearance. The combination of the pair of display driving units 102a, 102b is called a driving device 102. 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 will be omitted.

[0010] Fig. 2 is a conceptual side view specifically illustrating the first display driver 102a and the first light guiding optical system 103a of the first virtual image display device 100A. Fig. 3 is a conceptual plan view specifically illustrating the first display driver 102a and the first light guiding optical system 103a.

[0011] As shown in FIGS. 2 and 3 , the first display driver 102a includes an image light generation device 10, a projection optical system 20, and a drive circuit member 88. The image light generation device 10 is an optical engine including a display panel 11a. The projection optical system 20 is a collimator having a polarized diffractive lens 21. The image light ML generated by the image light generation device 10 is collimated by the projection optical system 20 and coupled to a first light-guiding optical system 103a including a light-guiding device 50. Collimation refers to optically adjusting diffused light to be parallel using an optical element, thereby converting the light into collimated light, i.e., parallel light. The drive circuit member 88 causes the display panel 11a to perform a display operation. Note that the optical device excluding the drive circuit member 88 in the first virtual image display device 100A 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, allowing the wearer US to view a virtual image.

[0012] Fig. 4 is a conceptual cross-sectional view specifically illustrating the first display driver 102a and the first light guiding optical system 103a. Fig. 5 is a conceptual rear view mainly illustrating the first light guiding optical system 103a.

[0013] As shown in FIG. 4 and other figures, in the first display drive unit 102a, the image light generation device 10 includes only one display panel 11a. That is, the display panel 11a includes pixels of three colors, RGB, with different wavelength ranges, and the pixels of each color or wavelength range are two-dimensionally arranged on the display panel 11a. The display panel 11a and the projection optical system 20 are fixed in a mutually positioned state by a lens barrel 30 shown in FIG. 2. The lens barrel 30, together with the drive circuit member 88, is supported in a mutually positioned state by a holder 35 that also serves as a cover, and is adhesively fixed to the first light guiding optical system 103a, specifically, to the light guiding device 50 (see FIG. 2).

[0014] The display panel 11a is a display element or display device that emits image light ML to form an image corresponding to a virtual image. Specifically, the display panel 11a is a display of an array of various light-emitting elements, such as OLEDs (organic light-emitting diodes), micro OLEDs, organic ELs (organic electroluminescence), inorganic ELs, LEDs, or micro LEDs, and forms still or moving images on a two-dimensional display surface parallel to the XY plane. The display panel 11a has light-emitting elements 14a. The light-emitting elements 14a are formed by two-dimensionally arranging a large number of pixels on a substrate along the XY plane. When the display panel 11a is an OLED display, each pixel constituting the light-emitting element 14a includes, in order from the substrate side, a cathode, an electron transport layer, a light-emitting layer, a hole layer, and a transparent electrode layer.

[0015] The display panel 11a is not limited to the self-luminous image light generating device 10, but may be configured with an LCD or other light modulation element, and may form an image by illuminating the light modulation element with a light source such as a background. Instead of an LCD, the display panel 11a may also be configured with LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micromirror device (specifically, DLP: a registered trademark), a laser beam scan, or the like.

[0016] The projection optical system 20 collimates, or parallelizes, the incident light. The projection optical system 20 includes only one polarizing diffractive lens 21. The polarizing diffractive lens 21 collimates the image light ML emitted from the display surface 11d of the display panel 11a to a state with a predetermined beam width, and emits the light toward the input diffractive optical element DI, which will be described later. In other words, the polarizing diffractive lens 21 produces collimated light on the exit side, resulting in higher light utilization efficiency than when collimated by a normal optical lens.

[0017] When predetermined circularly polarized light is incident on the polarizing diffractive lens 21, the polarizing diffractive lens 21 functions as a diffractive lens by itself. The polarizing diffractive lens 21 is also called a liquid crystal diffractive lens, a GP (geometric-phase) lens, a two-dimensional anisotropic diffractive optical element, or a geometric phase lens.

[0018] The polarized diffractive lens 21 has a refractive index anisotropy distribution, which is grasped in a plane by a large number of annular zones centered on the optical axis AX, and functions as a diffractive lens according to this refractive index anisotropy distribution and the polarization state of incident light. Specifically, if the polarized diffractive lens 21 has a refractive index anisotropy distribution such that the orientation of the optical axis rotates (actually repeating in the range of 0 to π) with increasing distance from the optical axis AX in two directions that are orthogonal to the central optical axis AX and orthogonal to each other, a geometric phase is formed in specific circularly polarized light incident thereon, and the circularly polarized light is diffracted at a diffraction angle reflecting the period length of the rotation of the optical axis in each direction, thereby reversing the polarization state. The polarized diffractive lens as a whole causes diffraction of specific circularly polarized light corresponding to the power formed by the lens shape, and reverses the state of circular polarization before and after passing through, for example, from right-handed circularly polarized light to left-handed circularly polarized light.

[0019] As described above, the polarized diffractive lens 21 has liquid crystal molecules oriented so that the amount of phase change increases from the center to the edges of the lens, resulting in a lens effect. The polarized diffractive lens 21 has a relatively small amount of phase change at the center of the lens, so light passing near the center of the lens travels straight. The polarized diffractive lens 21 also has a relatively large amount of phase change at the edges of the lens, so light passing near the edges of the lens experiences a strong light refraction effect.

[0020] The polarized diffractive lens 21 is a liquid crystal lens with a different focal length for each wavelength. Specifically, the focal lengths of the polarized diffractive lens 21 increase in the order of the first image light MLr for red, the second image light MLg for green, and the third image light MLb for blue. The focal lengths of the polarized diffractive lens 21 are determined by the orientation of the liquid crystal, the amount of phase change, the thickness of the liquid crystal, and the like. The greater the amount of phase change, the shorter the focal length. The focal length of the polarized diffractive lens 21 is, for example, approximately 10 mm to 25 mm.

[0021] Although not shown, the polarized diffractive lens 21 is formed by forming a thin film of a liquid crystal-containing material layer on a transparent substrate and has a thin plate-like shape. The liquid crystal-containing material layer contains a predetermined liquid crystal material. The orientation axes of the liquid crystal molecules are aligned parallel to, for example, the X direction in the region near the optical axis AX to form an initial geometric phase. The orientation axes gradually rotate within the XY plane as the distance from the optical axis AX increases, i.e., depending on the distance or radius from the optical axis AX. In other words, the rotation angle of the orientation axes of the liquid crystal molecules increases with the distance from the optical axis AX, and this cycle repeats periodically. In the liquid crystal compound layer, the orientation axes of the liquid crystal molecules are aligned, for example, with a constant orientation in the Z direction parallel to the optical axis AX. The polarized diffractive lens 21 can be manufactured, for example, by coating a liquid crystal-containing material film, which is a mixture of a liquid crystal material and a UV-curable organic material layer, on a substrate and then two-dimensionally scanning the liquid crystal-containing material film with UV laser light of a predetermined polarization state to adjust the orientation axes of the liquid crystal molecules and cure the organic material layer. This allows the alignment axes of the liquid crystal molecules in the liquid crystal-containing material layer to be three-dimensionally controlled and fixed, resulting in a liquid crystal compound layer in which the rotation angle of the alignment axis increases the further away from the optical axis AX as described above. Such a polarized diffractive lens 21 itself is a known technology, for example, as a polarization-dependent liquid crystal Fresnel lens (see, for example, the literature, Kohei Noda, et al. Applied Optics, February 10, 2017, Vol. 56, No. 5: 1302).

[0022] The polarized diffractive lens 21 can also be produced by the method for producing a liquid crystal optical element described in JP-A-2008-501147.

[0023] The focal length of the polarized diffractive lens 21 can be increased or decreased depending on the manufacturing method and liquid crystal material. In the liquid crystal compound layer, for example, when increasing the rotation angle of the alignment axis of the liquid crystal molecules the further away from the optical axis AX, the absolute value of the power of the polarized diffractive lens 21 can be increased and the focal length can be adjusted by increasing the rate of increase in the rotation angle with respect to the distance or radius from the optical axis AX, in other words, by reducing the rotation period of the alignment axis. When circularly polarized light passes through the polarized diffractive lens 21, loss is close to zero, and the polarized diffractive lens 21 exhibits almost 100% transmittance.

[0024] The polarized diffractive lens 21 may be a diffractive lens as long as it has wavelength dependency in terms of focal length. For example, a relief type diffractive lens or an amplitude type diffractive lens can be used as the diffractive lens.

[0025] 2 to 5, the first light-guiding optical system 103a includes a light-guiding device 50 that enables color display. As shown in Fig. 4 and other figures, the light-guiding device 50 includes a plurality of light-guiding members 51, 52, and 53 for each color or wavelength, and extends approximately parallel to the XY plane.

[0026] The first light guiding member 51 diffracts the first red image light MLr out of the image light ML emitted from the display panel 11a in accordance with its wavelength. As shown in Figures 4 and 5, the first light guiding member 51 includes a first light guiding plate 51a, a first incident diffraction layer 51b, a first pupil enlargement grating layer 51e, and a first exit diffraction layer 51c.

[0027] First light guide plate 51a is a member formed from a parallel plate, and has first total reflection surface 51i and second total reflection surface 51o, which are a pair of flat surfaces extending in the XY plane.

[0028] The first input diffraction layer 51b is an input diffractive optical element DI that diffracts the first image light MLr collimated from the polarizing diffraction lens 21 and causes it to enter the first light guide plate 51a while propagating laterally. The first pupil enlargement grating layer 51e is a pupil enlargement diffractive optical element DD that causes the first image light MLr, which is guided or propagated laterally in the first light guide plate 51a, to propagate downward while expanding the pupil size. The first output diffraction layer 51c is an output diffractive optical element DO that causes the first image light MLr, which propagates downward in the first light guide plate 51a, to exit toward a pupil position PP (see FIG. 2) set inside the first light guide plate 51a where the eye EY (see FIG. 2) is located, while expanding the pupil size of the first image light MLr. The first image light MLr is incident on the pupil position PP along the exit optical axis OX (see FIG. 2) at an angle corresponding to the pixel position.

[0029] The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil expansion grating layer 51e are formed on a second total reflection surface 51o that is located on the external side, i.e., the +Z side, of the light guide plate 51a. The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil expansion grating layer 51e are designed to function as a reflective diffraction grating that partially transmits external light.

[0030] The second light guiding member 52 diffracts the second green image light MLg out of the image light ML emitted from the display panel 11a in accordance with its wavelength, similar to the first light guiding member 51. The second light guiding member 52 includes a second light guiding plate 52a, a second incident diffraction layer 52b, a second pupil enlargement grating layer 52e, and a second exit diffraction layer 52c.

[0031] Second light guide plate 52a is a member formed from a parallel plate, and has first total reflection surface 52i and second total reflection surface 52o, which are a pair of flat surfaces extending in the XY plane.

[0032] The second input diffraction layer 52b is an input diffractive optical element DI that diffracts the second image light MLg collimated from the polarizing diffractive lens 21 and causes it to enter the second light guide plate 52a while diffracting it, thereby propagating it laterally. The second pupil enlargement grating layer 52e is a pupil enlargement diffractive optical element DD that causes the second image light MLg, which is guided or propagated laterally in the second light guide plate 52a, to propagate downward while expanding the pupil size. The second output diffraction layer 52c is an output diffractive optical element DO that causes the second image light MLg, which propagates downward in the second light guide plate 52a, to exit toward a pupil position PP (see FIG. 2) set inside where the eye EY (see FIG. 2) is located.

[0033] The incident diffraction layer 52b, the exit diffraction layer 52c, and the pupil expansion grating layer 52e are formed on a second total reflection surface 52o disposed on the external side of the light guide plate 52a. The incident diffraction layer 52b, the exit diffraction layer 52c, and the pupil expansion grating layer 52e are designed to function as a reflective diffraction grating that partially transmits external light.

[0034] The third light guiding member 53 diffracts the third blue image light MLb of the image light ML emitted from the display panel 11a in accordance with its wavelength, similar to the first light guiding member 51. The third light guiding member 53 includes a third light guiding plate 53a, a third incident diffraction layer 53b, a third pupil enlargement grating layer 53e, and a third exit diffraction layer 53c.

[0035] The third light guide plate 53a is a member formed from a parallel plate, and has a pair of flat surfaces extending in the XY plane, that is, a first total reflection surface 53i and a second total reflection surface 53o.

[0036] The third input diffraction layer 53b is an input diffractive optical element DI that diffracts the third image light MLb collimated from the polarizing diffraction lens 21 and causes it to enter the third light guide plate 53a while diffracting it, thereby propagating it laterally. The third pupil enlargement grating layer 53e is a pupil enlargement diffractive optical element DD that causes the third image light MLb, which is guided or propagated laterally in the third light guide plate 53a, to propagate downward while expanding the pupil size. The third output diffraction layer 53c is an output diffractive optical element DO that causes the third image light MLb, which propagates downward in the third light guide plate 53a, to exit toward a pupil position PP (see FIG. 2) set inside where the eye EY (see FIG. 2) is located.

[0037] The incident diffraction layer 53b, the exit diffraction layer 53c, and the pupil expansion grating layer 53e are formed on the second total reflection surface 53o located on the external side of the light guide plate 53a. The incident diffraction layer 53b, the exit diffraction layer 53c, and the pupil expansion grating layer 53e are designed to function as a reflective diffraction grating that partially transmits external light.

[0038] The first-, second-, and third-emission diffraction layers 51c, 52c, and 53c are arranged to be spaced apart but overlap one another. When viewed from the eye EY, the first image light MLr emitted from the first-emission diffraction layer 51c, the second image light MLg emitted from the second-emission diffraction layer 52c, and the third image light MLb emitted from the third-emission diffraction layer 53c are observed as a single virtual image formed by the three image lights MLr, MLg, and MLb overlapping and being combined.

[0039] The diffractive optical elements DI, DO, and DD constituting the first light-guiding member 51, i.e., the diffractive layers 51b and 51c and the pupil enlargement grating layer 51e, are configured so that the peak wavelength of their diffraction characteristics matches the peak wavelength of red light emitted by the display panel 11a (e.g., 600 nm). Similarly, the diffractive optical elements DI, DO, and DD constituting the second light-guiding member 52 are configured so that the peak wavelength of their diffraction characteristics matches the peak wavelength of green light emitted by the display panel 11a (e.g., 530 nm). Similarly, the diffractive optical elements DI, DO, and DD constituting the third light-guiding member 53 are configured so that the peak wavelength of their diffraction characteristics matches the peak wavelength of blue light emitted by the display panel 11a (e.g., 470 nm). This improves the light utilization efficiency of the diffractive optical elements DI, DO, and DD, enabling the production of bright images.

[0040] The input diffractive optical element DI, the output diffractive optical element DO, and the pupil enlargement diffractive optical element DD are formed, for example, from a surface relief type diffractive element or diffraction grating. The surface relief type diffractive grating is formed by nanoimprinting, but is not limited to this. It can also be formed by etching the surface of the light guide plates 51a, 52a, and 53a, or by attaching a diffractive element or diffraction grating. The material of the diffraction grating is a nanoimprint material when formed by nanoimprinting, and the same material as the light guide plates 51a, 52a, and 53a when formed by etching. The material of the light guide plates 51a, 52a, and 53a is, for example, glass, resin, etc.

[0041] The input diffractive optical element DI, the output diffractive optical element DO, and the pupil enlargement diffractive optical element DD may be formed from volume holograms.

[0042] As described above, by having the light guiding device 50 include a plurality of light guiding members that diffract each of the image lights MLr, MLg, and MLb, it is possible to optimize the diffraction efficiency according to the wavelength range of the image light ML. Furthermore, by arranging the first light guiding member 51, the second light guiding member 52, and the third light guiding member 53 in this order from the projection optical system 20 or the polarizing diffraction lens 21 side, it is possible to arrange the light guiding members in accordance with the focal lengths of the polarizing diffraction lens 21 for each wavelength.

[0043] The position of the exit pupil Lx of the projection optical system 20 or the polarizing diffractive lens 21 is the position where the light flux of the image light ML is most narrowed. The exit pupil Lx corresponding to the wavelength of the polarizing diffractive lens 21 is set at the position of the input diffractive optical element DI corresponding to the wavelength in each light-guiding member 51, 52, 53. In other words, the position of the exit pupil Lx corresponding to the image light MLr, MLg, MLb in each wavelength range that has passed through the polarizing diffractive lens 21 coincides or nearly coincides with the position of the input diffractive optical element DI. As a result, for each wavelength of the image light ML, the maximum amount of image light is taken in by the light guide plate, while color unevenness in the image viewed by the wearer US is reduced, thereby improving the image quality.

[0044] Furthermore, the size of the input diffractive optical element DI corresponding to the wavelength is set to match or approximately match the size of the exit pupil Lx corresponding to the wavelength of the polarizing diffractive lens 21. This allows the image light ML to be efficiently taken into the light guide plates 51a, 52a, and 53a. Furthermore, the light utilization efficiency of the image light ML is improved, and the image quality is improved.

[0045] The first embodiment of the virtual image display devices 100A and 100B includes a display panel 11a that emits image light ML, a polarized diffractive lens 21 that collimates the image light ML from the display panel 11a and has a focal length that varies for each wavelength, and a plurality of light-guiding members 51, 52, and 53 that correspond to the wavelengths, and the plurality of light-guiding members 51, 52, and 53 each include light-guiding plates 51a, 52a, and 53a that guide the image light ML, an input diffractive optical element DI that makes the image light ML incident on the light-guiding plates 51a, 52a, and 53a, and an output diffractive optical element DO that makes the image light ML emit from the light-guiding plates 51a, 52a, and 53a.

[0046] In the virtual image display devices 100A and 100B, the image light MLr, MLb, and MLg emitted from the display panel 11a is diffracted by the polarized diffractive lens 21, and the size of the exit pupil Lx is adjusted to be appropriate for each wavelength by the input diffractive optical element DI provided in the light guiding members 51, 52, and 53 corresponding to each wavelength. In this way, the size of the exit pupil Lx for each wavelength is optimized, thereby improving the image quality.

[0047] 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 common parts will be omitted.

[0048] 6, in the first light guiding optical system 103a or the light guiding device 50 of the virtual image display device 100A of this embodiment, the incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil expansion grating layer (not shown) of the first light guiding member 51 are formed on a first total reflection surface 51i arranged on the projection optical system 20 side, i.e., the -Z side. The incident diffraction layer 51b, the exit diffraction layer 51c, and the pupil expansion grating layer are designed to function as a transmission diffraction grating that partially transmits external light.

[0049] The incident diffraction layer 52b, the exit diffraction layer 52c, and the pupil enlargement grating layer (not shown) of the second light-guiding member 52 are formed on the first total reflection surface 52i arranged on the projection optical system 20 side, similar to the first light-guiding member 51.

[0050] The incident diffraction layer 53b, the exit diffraction layer 53c, and the pupil enlargement grating layer (not shown) of the third light-guiding member 53 are formed on the first total reflection surface 53i arranged on the projection optical system 20 side, similar to the first light-guiding member 51.

[0051] Third Embodiment Hereinafter, a virtual image display device according to a third embodiment of the present invention will be described. Note that the virtual image display device of the third embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of common parts will be omitted.

[0052] 7, in a virtual image display device 100A of the present embodiment, the image light generation device 10 of the first display drive unit 102a includes three display panels 11r, 11b, and 11g and a cross dichroic prism 18. The projection optical system 20 is a collimator including a polarizing diffractive lens 21.

[0053] The first display panel 11r for red emits a first image light MLr for red. The first display panel 11r is, for example, an OLED display, and forms a still image or a moving image on a two-dimensional display surface 11d parallel to the YZ plane, and emits the first image light MLr.

[0054] The third display panel 11b for blue emits third image light MLb for blue. Like the first display panel 11r for red, the third display panel 11b is, for example, an OLED display, and forms a still image or a moving image on a two-dimensional display surface 11d parallel to the YZ plane, and emits third image light MLb. The light-emitting elements 14a incorporated in the third display panel 11b for blue have a different emission wavelength from the light-emitting elements 14a of the first display panel 11r for red. In other words, the third image light MLb has a different wavelength range from the first image light MLr.

[0055] The second display panel 11g for green emits second image light MLg for green. Like the first display panel 11r for red, the second display panel 11g is, for example, an OLED display, and forms a still image or a moving image on a two-dimensional display surface 11d parallel to the XY plane and emits second image light MLg. The light-emitting elements 14a incorporated in the second display panel 11g for green have a different emission wavelength from the light-emitting elements 14a of the red and blue display panels 11r and 11b. In other words, the second image light MLg has a different wavelength range from the first image light MLr and the third image light MLb.

[0056] The light-emitting elements 14a incorporated in the display panels 11r, 11b, and 11g are all OLED displays with first-order resonant cavities. Therefore, the orientation characteristics of the display panels 11r, 11b, and 11g are such that the light intensity is high in the frontal direction parallel to the optical axis AX and rapidly decreases in directions slightly tilted from the frontal direction. The radiation angles at which the light intensity reaches half their maximum are defined as the radiation angles, and the radiation angles of the first image light MLr, the third image light MLb, and the second image light MLg from the pixels are all within approximately 20°. The dichroic mirrors 18r and 18b of the cross dichroic prism 18, which will be described later, are designed based on these radiation angles of the image lights MLr, MLb, and MLg.

[0057] The first display panel 11r for red is fixed to face the first light incident surface 18ib of the cross dichroic prism 18. The first display panel 11r causes the first image light MLr to be incident on the cross dichroic prism 18 from the first light incident surface 18ib. The third display panel 11b for blue is fixed to face the second light incident surface 18ic of the cross dichroic prism 18. The third display panel 11b causes the third image light MLb to be incident on the cross dichroic prism 18 from the second light incident surface 18ic. The second display panel 11g for green is fixed to face the third light incident surface 18ia of the cross dichroic prism 18. The second display panel 11g causes the second image light MLg to be incident on the cross dichroic prism 18 from the third light incident surface 18ia.

[0058] The cross dichroic prism 18 is made by joining four right-angled triangular prisms made of glass or other materials together so that their right-angled edges coincide, and has two dichroic mirrors 18r and 18b embedded at the joints, which are perpendicular to each other. One of the dichroic mirrors, 18r, is disposed at a 45° angle with the first entrance 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 a 45° angle with the second entrance 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.

[0059] The first image light MLr incident on the first entrance surface 18ib of the cross dichroic prism 18 from the first 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 third image light MLb incident on the second entrance surface 18ic of the cross dichroic prism 18 from the third 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 second image light MLg incident on the third entrance surface 18ia of the cross dichroic prism 18 from the second green display panel 11g passes through the dichroic mirrors 18r and 18b toward the projection optical system 20 without being reflected, 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 second image light MLg. As a result, the cross dichroic prism 18 synthesizes an image in which the first image light MLr, the third image light MLb, and the second image light MLg are superimposed, and the synthesized image is emitted as image light ML and can be incident on the projection optical system 20.

[0060] In the cross dichroic prism 18, the cross axis CX extends along the intersection line between 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 horizontal direction perpendicular to the light guide plates 51a, 52a, and 53a, that is, in the Z direction.

[0061] The projection optical system 20 is a substantially telecentric optical system with respect to the display panels 11r, 11b, and 11g, which are the object side. That is, the chief ray of the image light MLr, MLb, and MLg emitted from each of the light-emitting elements 14a, which form the display surfaces 11d of the display panels 11r, 11b, and 11g, passes through the light incident surfaces 18ib, 18ic, and 18ia of the cross dichroic prism 18 in a state substantially parallel to the optical axis AX, enters the cross dichroic prism 18, and emerges from the cross dichroic prism 18 substantially parallel to the optical axis AX. As a result, the image light MLr, MLb, and MLg within a predetermined angle range are incident on the dichroic mirrors 18r and 18b, thereby suppressing light loss due to the dichroic mirrors 18r and 18b.

[0062] The arrangement of the display panels 11r, 11b, and 11g can be changed as appropriate.

[0063] The virtual image display device 100A of this embodiment may have the same configuration as the first light guiding optical system 103a of the second embodiment.

[0064] Furthermore, the display panels 11r, 11b, and 11g of the present embodiment can be appropriately changed to other than OLED displays, and may be, for example, micro OLED displays, micro LED displays, or the like.

[0065] The virtual image display device 100A of the third embodiment described above includes the three display panels 11r, 11b, and 11g and the cross dichroic prism 18, and thus can adjust the size of the exit pupil Lx with high precision by adjusting the positions of the display panels 11r, 11b, and 11g. Furthermore, the image light MLr, MLb, and MLg emitted from the three display panels 11r, 11b, and 11g are combined, and therefore the luminance of the combined image light ML can be increased.

[0066] If the projection optical system 20 is configured with a conventional lens, it is not possible to collimate each pixel even if the positions of the display panels 11r, 11b, and 11g are changed, and out-of-focus images may occur.

[0067] [Fourth embodiment] A virtual image display device according to a fourth embodiment of the present invention will be described below. The virtual image display device of the fourth embodiment is a partial modification of the virtual image display device of the third embodiment, and a description of common parts will be omitted.

[0068] 8, in the virtual image display device 100A of the present embodiment, the image light generation device 10 of the first display drive unit 102a has an optical lens 70 between the three display panels 11r, 11b, and 11g and the cross dichroic prism 18. Specifically, a lens 71r is disposed as the optical lens 70 between the first display panel 11r for red and the light incident surface 18ib of the cross dichroic prism 18. A lens 71b is disposed as the optical lens 70 between the third display panel 11b for blue and the light incident surface 18ic of the cross dichroic prism 18. A lens 71g is disposed as the optical lens 70 between the second display panel 11g for green and the light incident surface 18ia of the cross dichroic prism 18.

[0069] The virtual image display device 100A of the fourth embodiment described above can adjust the size and position of the exit pupil Lx with higher precision by providing an optical lens 70 between the display panels 11r, 11b, 11g and the cross dichroic prism 18.

[0070] Fifth Embodiment Hereinafter, a virtual image display device according to a fifth embodiment of the present invention will be described. Note that the virtual image display device of the fifth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of common parts will be omitted.

[0071] As shown in FIG. 9, in the virtual image display device 100A of this embodiment, the light guide device 50 of the first display optical system 102a is made up of two light guide members 151 and 152.

[0072] In the first light guiding member 151, the grating period and the like of the incident diffraction layer 51b are set so that the first image light MLr and the second image light MLg propagate, for example. In the second light guiding member 152, the grating period and the like of the incident diffraction layer 52b are set so that the third image light MLb propagate, for example. In this case, although one of the positions of the exit pupils Lx, Lx corresponding to the image light MLr, MLg in the two wavelength ranges is shifted from the incident diffraction layer 51b of the first light guiding member 151, the light utilization efficiency is higher than when the image light MLr, MLg is collimated by a normal optical lens.

[0073] In the first light-guiding member 151, the grating period or the like of the incident diffraction layer 51b may be set so that the first image light MLr propagates. In the second light-guiding member 152, the grating period or the like of the incident diffraction layer 52b may be set so that the second image light MLg and the third image light MLb propagate.

[0074] [Other matters] The structure described above is an example, and various modifications can be made within the scope of achieving the same function.

[0075] In the above, the arrangement of the input diffractive optical element DI, output diffractive optical element DO, and pupil enlargement diffractive optical element DD, the orientation and angle of the diffraction grating, the propagation direction, etc. can be changed as appropriate.

[0076] Light guiding device 50 is not limited to including input diffractive optical element DI, output diffractive optical element DO, and pupil enlargement diffractive optical element DD, and for example, pupil enlargement diffractive optical element DD may be omitted. In this case, collimated image light ML is guided into light guiding plates 51 a, 52 a, and 53 a by input diffractive optical element DI to propagate laterally, and output diffractive optical element DO causes image light ML propagating laterally within light guiding plates 51 a, 52 a, and 53 a to be emitted toward pupil position PP inside.

[0077] The virtual image display device 100A may correct the lateral magnification of the image by displaying on the display panel 11a.

[0078] The F-number of the polarized diffractive lens 21 can be changed as appropriate.

[0079] In the above, the virtual image display devices 100A and 100B can be used as HMDs, but this is not limited to this and the present invention can be applied to various optical devices, for example, a head-up display (HUD).

[0080] In a specific embodiment, the virtual image display device includes a display panel that emits image light, a polarized diffractive lens that collimates the image light from the display panel and has a different focal length for each wavelength, and a plurality of light-guiding members that correspond to the wavelengths, each of which has a light-guiding plate that guides the image light, an input diffractive optical element that makes the image light incident on the light-guiding plate, and an output diffractive optical element that makes the image light emit from the light-guiding plate.

[0081] In the virtual image display device, the image light emitted from the display panel is diffracted by the polarized diffractive lens, and the input diffractive optical element provided in the light guide member corresponding to each wavelength optimizes the exit pupil size for each wavelength, thereby improving the image quality.

[0082] In a specific embodiment of the virtual image display device, the exit pupil corresponding to the wavelength of the polarized diffractive lens is set at the position of the input diffractive optical element corresponding to the wavelength. In this case, for each wavelength of the image light, the maximum amount of image light is taken into the light guide plate, and color unevenness in the image viewed by the wearer US is reduced, thereby improving the image quality.

[0083] In a specific embodiment of the virtual image display device, the size of the input diffractive optical element corresponding to the wavelength is set to match the size of the exit pupil of the polarized diffractive lens corresponding to the wavelength. In this case, the image light can be efficiently taken into the light guide plate. In this case, the light utilization efficiency of the image light is improved, and the image quality is improved.

[0084] In a specific embodiment of the virtual image display device, the image light includes first image light, second image light, and third image light having different wavelength ranges, the first image light having a red wavelength range, the second image light having a green wavelength range, and the third image light having a blue wavelength range, and the polarized diffractive lens has an increasing focal length in the order of the first image light, the second image light, and the third image light.

[0085] In a specific aspect of the virtual image display device, the image light includes first image light, second image light, and third image light having different wavelength ranges, and the plurality of light guide members include a first light guide member that diffracts the first image light, a second light guide member that diffracts the second image light, and a third light guide member that diffracts the third image light. In this case, it is possible to optimize the diffraction efficiency according to the wavelength range of the image light.

[0086] In a specific aspect of the virtual image display device, the image light includes first, second, and third image lights having different wavelength ranges, the first image light having a red wavelength range, the second image light having a green wavelength range, and the third image light having a blue wavelength range, and a first light guiding member, a second light guiding member, and a third light guiding member are arranged in this order from the polarizing diffractive lens side. In this case, the light guiding members can be arranged in accordance with the focal lengths of the polarizing diffractive lens for each wavelength.

[0087] In a specific embodiment, the virtual image display device includes a first display panel that emits the first image light, a second display panel that emits the second image light, a third display panel that emits the third image light, and a cross dichroic prism that combines the first image light, the second image light, and the third image light. In this case, by adjusting the position of each display panel, the size of the exit pupil can be adjusted with high precision. Furthermore, by combining the first image light, the second image light, and the third image light, a high-brightness virtual image can be displayed.

[0088] In a specific embodiment of the virtual image display device, optical lenses are provided between the cross dichroic prism and the first, second, and third display panels, allowing the size and position of the exit pupil to be adjusted with higher precision.

[0089] In a specific embodiment, the optical unit includes a display panel that emits image light, a polarized diffractive lens that collimates the image light from the display panel and has a focal length that varies depending on the wavelength, and a plurality of light-guiding members that correspond to the wavelengths, each of which has a light-guiding plate that guides the image light, an input diffractive optical element that makes the image light incident on the light-guiding plate, and an output diffractive optical element that makes the image light emit from the light-guiding plate. [Explanation of symbols]

[0090] 10...image light generating device, 11a, 11r, 11g, 11b...display panel, 18...cross dichroic prism, 20...projection optical system, 21...polarized diffraction lens, 30...lens barrel, 50...light guiding device, 51, 52, 53, 151, 152...light guiding member, 51a, 52a, 53a...light guiding plate, 51b, 52b, 53b...incident diffraction layer, 51c, 52c, 53c...exit diffraction layer, 51e, 52e, 53e...pupil expansion grating layer, 60...cover member, 70...optical lens, 71 r, 71b, 71g...lens, 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-guiding optical system, AX...optical axis, DD...pupil expansion diffractive optical element, DI...input diffractive optical element, DO...output diffractive optical element, EY...eye, Lx...exit pupil, ML, MLr, MLg, MLb...image light, OX...exit optical axis, PP...pupil position, US...wearer

Claims

1. a display panel that emits image light; a polarized diffractive lens that collimates the image light from the display panel and has a different focal length for each wavelength; a plurality of light guide members corresponding to the wavelengths; Equipped with each of the plurality of light guide members includes a light guide plate that guides the image light, an input diffractive optical element that causes the image light to enter the light guide plate, and an output diffractive optical element that causes the image light to exit from the light guide plate; Virtual image display device.

2. an exit pupil of the polarized diffractive lens corresponding to the wavelength is set at a position of the input diffractive optical element corresponding to the wavelength; The virtual image display device according to claim 1 .

3. a size of the input diffractive optical element corresponding to the wavelength is set to match a size of an exit pupil of the polarized diffractive lens corresponding to the wavelength; The virtual image display device according to claim 1 .

4. the image light includes first image light, second image light, and third image light having different wavelength ranges; the first image light has a red wavelength range, the second image light has a green wavelength range, the third image light has a blue wavelength range, the polarized diffractive lens has focal lengths that become longer in the order of the first image light, the second image light, and the third image light; The virtual image display device according to claim 1 .

5. the image light includes first image light, second image light, and third image light having different wavelength ranges; the plurality of light guiding members include a first light guiding member that diffracts the first image light, a second light guiding member that diffracts the second image light, and a third light guiding member that diffracts the second image light; The virtual image display device according to claim 1 .

6. the image light includes first image light, second image light, and third image light having different wavelength ranges; the first image light has a red wavelength range, the second image light has a green wavelength range, the third image light has a blue wavelength range, the first light guiding member, the second light guiding member, and the third light guiding member are arranged in this order from the polarizing diffractive lens side; The virtual image display device according to claim 1 .

7. the image light includes first image light, second image light, and third image light having different wavelength ranges; a first display panel that is the display panel that emits the first image light; a second display panel that emits the second image light having a wavelength range different from that of the first image light; a third display panel that emits the third image light having a wavelength range different from that 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 .

8. an optical lens is provided between the cross dichroic prism and the first display panel, the second display panel, and the third display panel; 8. The virtual image display device according to claim 7.

9. a display panel that emits image light; a polarized diffractive lens that collimates the image light from the display panel and has a different focal length for each wavelength; a plurality of light guide members corresponding to the wavelengths; Equipped with each of the plurality of light guide members includes a light guide plate that guides the image light, an input diffractive optical element that causes the image light to enter the light guide plate, and an output diffractive optical element that causes the image light to exit from the light guide plate; Optical unit.

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