Virtual image display device and optical unit

Abstract

A virtual image display device and an optical unit. The imaging system of the virtual image display device is thinned. A virtual image display device (100A, 100B) or an optical unit (100) is provided with: a display (40) that emits video light (ML); and a polarization selection lens (50a) that is disposed so as to face the display (40) and that has a refractive power that selectively acts on polarized light that is image light (ML), the polarization selection lens (50a) having, in order from the display (40) side: a polarization diffraction lens (51) that has a positive refractive power with respect to the image light (ML) that is circularly polarized light and a negative refractive power with respect to external light (OL) that is circularly polarized light; and an auxiliary lens (52) having the same positive refractive power as the polarization diffraction lens (51).

Description

Technical Field

[0001] The present invention relates to a virtual image display device and an optical unit capable of observing a virtual image, and more particularly to a virtual image display device using a polarization diffraction lens. Background Art

[0002] A known polarization conversion system includes a geometric phase element and a delay element (see Patent Document 1). The geometric phase element has optical anisotropy with a local optical axis direction that varies nonlinearly in at least one dimension along its surface. The delay element is configured to receive light output from the geometric phase element.

[0003] Patent Document 1: Japanese Patent Application No. 2016-519327

[0004] The geometric phase element in the aforementioned polarization conversion system converges right-handed circularly polarized light and diverges left-handed circularly polarized light. Therefore, even if the system of Patent Document 1 were simply applied to a virtual image display device, it would be difficult to achieve both image observation and external light observation. In the case of a see-through virtual image display device, the geometric phase element would need to be positioned away from the see-through area, leading to a larger optical system. Summary of the Invention

[0005] A virtual image display device and an optical unit according to one aspect of the present invention include: a display that emits image light; and a polarization selection lens that is arranged opposite to the display and has a refractive power that selectively acts on polarized light serving as image light, the polarization selection lens including, in order from the display side: a polarization diffraction lens that has positive refractive power for image light serving as circularly polarized light and negative refractive power for external light serving as circularly polarized light; and an auxiliary lens that has the same positive refractive power as the polarization diffraction lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a front view illustrating the appearance of the virtual image display device according to the first embodiment when it is worn.

[0007] Figure 2 It is a schematic perspective view illustrating the structure of the virtual image display device.

[0008] Figure 3 It is a schematic side cross-sectional view illustrating the structure of the display optical system.

[0009] Figure 4 is a rear view illustrating the image display panel.

[0010] Figure 5 is a rear view illustrating a patterned polarizing element.

[0011] Figure 6 This is a diagram illustrating the function of a polarization diffraction lens.

[0012] Figure 7 A diagram illustrating the state of light in a display optical system.

[0013] Figure 8 It is a schematic side cross-sectional view for explaining the virtual image display device according to the second embodiment.

[0014] Figure 9 It is a schematic side cross-sectional view illustrating a virtual image display device according to a third embodiment.

[0015] Figure 10 It is a schematic side cross-sectional view for explaining a virtual image display device according to a fourth embodiment.

[0016] Figure 11 It is a schematic perspective view illustrating the structure of the virtual image display device according to the fifth embodiment.

[0017] Figure 12 It is an explanation Figure 11 A schematic side sectional view of the structure of the display optical system.

[0018] Figure 13 It is an explanation Figure 11 A diagram showing the state of light in an optical system.

[0019] Figure 14 It is an explanation Figure 11 FIG. 1 is a diagram illustrating the operation of the virtual image display device.

[0020] Figure 15 It is a schematic side cross-sectional view illustrating the structure of the display optical system and the state of light of the virtual image display device according to the sixth embodiment.

[0021] Figure 16 It is an explanation Figure 15 FIG. 1 is a diagram illustrating the operation of the virtual image display device.

[0022] Label Description

[0023] 23: 1 / 4 wavelength plate; 2a: imager; 10: light source; 11: light guide plate; 12: ferroelectric liquid crystal panel; 14: liquid crystal modulation component; 15, 16: polarizing plate; 20: composite display component; 21: light guide component; 22: transmissive liquid crystal panel; 25: image display panel; 25a: light emitting area; 25b: transmissive area; 26: patterned polarizing element; 26a: first polarizing element; 26b: second polarizing element; 27: polarizing plate; 28: time-division 1 / 2 wavelength plate; 28a, 28b: liquid crystal wavelength plate; 31: liquid crystal layer; 40: display; 50: imaging system; 50a: polarization selection lens; 51: polarization diffraction lens; 52: auxiliary lens; 52a: Refractive lens; 52b: diffraction lens; 60, 75: polarized light half-mirror; 80: control device; 81: drive circuit; 90: user terminal; 100: optical unit; 100A, 100B: virtual image display device; 100C: temple; 102a, 102b: display drive unit; 103a, 103b: display optical system; AX: optical axis; EY: eye; GP1, GP2: polarized diffraction lens; IL: illumination light; LCP: left circularly polarized light; RCP: right circularly polarized light; LL: backlight source; ML: image light; OL: external light; PX: pixel; PX(C): image light generating pixel; PX(T): external light transmitting pixel; US: wearer. DETAILED DESCRIPTION

[0024] First embodiment

[0025] Below, refer to Figures 1 to 7 , a virtual image display device according to a first embodiment of the present invention is described.

[0026] Figure 1 1 is a front view illustrating a wearing state of a head-mounted display, that is, a head-mounted display device 200. The head-mounted display device (hereinafter also referred to as HMD) 200 allows an observer or wearer US wearing the head-mounted display device 200 to recognize an 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 eyes EY of the observer or wearer US wearing the HMD 200 are aligned. The +Y direction corresponds to the upper direction of the wearer US perpendicular to the horizontal direction in which the eyes EY are aligned. The +Z direction corresponds to the front or forward direction of the wearer US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0027] 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 temples 100C supporting the virtual image display devices 100A and 100B, and a user terminal 90 serving as an information terminal. The first virtual image display device 100A comprises a first display driver 102a disposed at the top and a first display optical system 103a covering the front of the eye. The second virtual image display device 100B comprises a second display driver 102b disposed at the top and a second display optical system 103b covering the front of the eye. The HMD 200, which combines the first and second virtual image display devices 100A and 100B, is also a virtual image display device in a broad sense. The pair of temples 100C serve as a wearing component or support device 106 worn on the head of the wearer US. They support the upper ends of the pair of display optical systems 103a and 103b via the display driver 102a and 102b, which appear to be integrated. A combination of the pair of display driving units 102 a and 102 b is referred to as a driving device 102 .

[0028] Figure 2 It is a schematic perspective view for explaining the structure of the first display optical system 103a of the first virtual image display device 100A. Figure 3 This is a schematic side cross-sectional view illustrating the structure of the first display optical system 103a. The first display optical system 103a includes a plate-shaped display 40 that forms a two-dimensional image and emits image light ML corresponding thereto, and an imaging system 50 that functions as a lens for the image light ML emitted from the display 40 to form a virtual image.

[0029] The display 40 emits image light ML and transmits external light OL. The display 40 includes a composite display component 20 that forms and emits the image light ML. The composite display component 20 is a plate-shaped component extending along an XY plane perpendicular to the optical axis AX. The composite display component 20 includes, in order from the outside, an image display panel 25, a patterned polarizing element 26, and a quarter-wave plate 23. The composite display component 20 has a structure in which the image display panel 25, the patterned polarizing element 26, and the quarter-wave plate 23 are stacked and integrated within a frame (not shown). In this embodiment, the image display panel 25 and the patterned polarizing element 26 function as a polarized light separation component 41 that imparts different polarization components to the image light ML and the external light OL.

[0030] The display 40 is driven by the drive circuit 81 of the control device 80, which is incorporated into the first display drive unit 102a or the drive device 102. The composite display component 20 of the display 40 is positioned close to the eye EY, with the imaging system 50 interposed therebetween, enabling observation of a virtual image based on image light ML and perspective observation of the outside world. In the first display optical system 103a, the distance between the eye EY and the imaging system 50 in the direction of the optical axis AX is, for example, approximately 10 mm to 20 mm. Furthermore, the distance between the image display panel 25 of the display 40 and the imaging system 50 in the direction of the optical axis AX is, for example, approximately 5 mm to 25 mm.

[0031] The image display panel 25 is a self-luminous image light generating device that emits red, green, and blue image light ML. The image display panel 25 is an imager 2a that forms a still image or a moving image on a two-dimensional display surface parallel to the XY plane. The image display panel 25 is driven by the drive circuit 81 to perform display operations.

[0032] The image display panel 25 is, for example, a transmissive organic light-emitting diode (OLED) display, but may also be a micro-LED (μLED) display formed of an inorganic material or another self-luminous display device having transmissive properties. Furthermore, a configuration in which image light ML is projected onto a transparent screen using a projection optical system may be employed in place of the image display panel 25.

[0033] Figure 4 This is a rear view illustrating the image display panel 25. The image display panel 25 comprises a light-emitting region 25a that forms image light ML and a transmissive region 25b that transmits ambient light OL on a light-transmitting flat plate 25p. The flat plate 25p comprises a plurality of light-emitting regions 25a and transmissive regions 25b arranged in a matrix along the XY plane. Each light-emitting region 25a corresponds to a pixel PX, and sub-pixels of the three colors RGB are arranged therein.

[0034] Furthermore, a polarizing plate (not shown) that limits the second polarized light P2, similar to the second polarizing element 26b of the patterned polarizing element 26, is preferably disposed on the external side of the image display panel 25. This prevents the external light OL from passing through the light-emitting region 25a of the image display panel 25 when the image display panel 25 is not emitting light. Furthermore, instead of the polarizing plate, a light-shielding member may be disposed on the external side of the image display panel 25 at a position corresponding to the light-emitting region 25a to prevent the external light OL from passing through the light-emitting region 25a of the image display panel 25.

[0035] Figure 5: This is a rear view illustrating the pattern polarizing element 26. The pattern polarizing element 26 has a pattern formed by compounding two types of polarizing elements, and limits the image light ML and the external light OL to a first polarization direction and a second polarization direction, respectively. The pattern polarizing element 26 causes the polarization direction of the image light ML to become different from the polarization direction of the external light OL. The pattern polarizing element 26 has a plurality of first polarizing elements 26a and second polarizing elements 26b arranged in a matrix along the XY plane on a light-transmitting flat plate 26p. The first polarizing element 26a is arranged at a position corresponding to the light-emitting area 25a of the image display panel 25. The second polarizing element 26b is arranged at a position corresponding to the transmissive area 25b of the image display panel 25. The first polarizing element 26a limits the image light ML to a first polarized light P1 in a first polarization direction, specifically, to longitudinal polarized light or vertical polarized light. The second polarizing element 26b limits the external light OL to a second polarized light P2 in a second polarization direction perpendicular to the first polarization direction, specifically, to transverse polarized light or horizontal polarized light. The first polarizing element 26 a and the second polarizing element 26 b are, for example, wire-grid polarizing elements, and have polarization characteristics corresponding to the pattern direction of a fine metal grid formed of aluminum or the like.

[0036] In addition, the patterned polarization element 26 can also be a unit composed of a polarizer (a polarizer based on a wire grid or an absorption-type TAC film, etc.) and a patterned wavelength plate, which replaces the flat plate 26p and only allows overall uniform polarized light to pass through, and the patterned wavelength plate is patterned in a manner having a fast axis with a different direction depending on the pixels of the image display panel 25.

[0037] Figure 2The quarter-wave plate 23 shown in the figure has a principal axis midway between the X and Y directions, for example, and converts the image light ML and the external light OL from linearly polarized light to circularly polarized light. Here, the image light ML being circularly polarized light means that, when focusing on the vibration of the electric field component or magnetic field component of the image light ML, its vibration direction rotates at the frequency of the image light ML within a plane perpendicular to the direction of travel of the light, and the amplitude is constant regardless of its direction. Right-handed circularly polarized light refers to polarized light in which the vibration direction of the electric field component rotates clockwise when viewed from the side of an observer standing in the direction of travel of the light, and left-handed circularly polarized light is polarized light that rotates counterclockwise. However, in this specification, if the image light ML mainly contains right-handed circularly polarized light, then such image light ML will be referred to as right-handed circularly polarized light RCP, even if, for example, it contains linear polarized light in a specific direction. Similarly, if the image light ML mainly contains left-handed circularly polarized light, then such image light ML will be referred to as left-handed circularly polarized light LCP. In this specification, right-handed circularly polarized light (RCP) is also referred to as right-handed circularly polarized light (RCP), and left-handed circularly polarized light (LCP) is also referred to as left-handed circularly polarized light (LCP). The quarter-wave plate 23 can be made by coating a transparent resin substrate with a photo-crosslinkable polymer liquid crystal material to form a thin film and fixing its orientation, or by processing a birefringent crystal material such as quartz into a thin plate.

[0038] The imaging system 50 is arranged on the face side, that is, the -Z side, with respect to the display 40 or the composite display unit 20 to cover the front of the eye. The imaging system 50 functions as a positive lens or a collimator having positive refractive power for the image light ML.

[0039] The imaging system 50 includes a polarization-selective lens 50a. The polarization-selective lens 50a is an optical element that acts differently depending on the polarization of light. The polarization-selective lens 50a has a refractive power that selectively acts on the polarized light serving as the image light ML. In other words, the polarization-selective lens 50a functions as a lens with respect to the image light ML emitted from the display 40. That is, the polarization-selective lens 50a images the plurality of pixels constituting the image display panel 25 collectively, and enables the image formed on the image display panel 25 to be observed as a virtual image. On the other hand, the polarization-selective lens 50a functions as a parallel flat plate with respect to the external light OL passing through the display 40. That is, the external light OL passes through the display 40 in a straight manner and is thus observed as a direct-view image.

[0040] The polarization-selective lens 50a includes, in order from the outside or display 40 side, a polarization diffraction lens 51 and an auxiliary lens 52. The polarization diffraction lens 51 is a plate-shaped component extending along the XY plane. The auxiliary lens 52 has the same refractive power as the polarization diffraction lens 51. Here, "same" means that the refractive power of the auxiliary lens 52 is the same or approximately the same as the absolute value of the refractive power of the polarization diffraction lens 51. The polarization diffraction lens 51 and the auxiliary lens 52 are arranged close together in a parallel state.

[0041] When a specified circularly polarized light is incident, the polarization diffraction lens 51 functions as a positive lens alone. When a circularly polarized light opposite to the above-specified circularly polarized light is incident, the polarization diffraction lens 51 functions as a negative lens alone. The polarization diffraction lens 51 includes a liquid crystal layer, and for this liquid crystal layer, the farther away from the optical axis AX, the more the rotation angle of the orientation axis of the liquid crystal molecules increases, and this is repeated periodically to form an initial geometric phase. The direction of increase of the rotation angle of the orientation axis of the liquid crystal molecules of the polarization diffraction lens 51 is polarization-dependent. The polarization diffraction lens 51 is also called a liquid crystal diffraction lens, a GP (geometric-phase) lens, an anisotropic diffractive optical element (two-dimensional anisotropic diffractive optical elements) or a geometric phase lens. As described above, the auxiliary lens 52 is a lens having the same refractive power as the polarization diffraction lens 51, that is, a positive refractive power. The auxiliary lens 52, combined with the polarization diffraction lens 51, whose refractive power varies depending on the polarization, assists the refractive power of the polarization selective lens 50a as a whole. As a result, the polarization selective lens 50a functions as a positive lens for image light ML, while canceling out the refractive powers of the polarization diffraction lens 51 and the auxiliary lens 52 for ambient light OL, thereby functioning like parallel plate glass.

[0042] The focal lengths of the polarizing diffraction lens 51 are ±f. The focal length of the auxiliary lens 52 is +f. By combining the polarizing diffraction lens 51 and the auxiliary lens 52, a lens can be realized that functions as a lens with a short focal length for light in one polarization direction while transmitting light in the other polarization direction.

[0043] In this embodiment, the auxiliary lens 52 is a refractive lens 52a. The refractive lens 52a is, for example, a convex lens or a Fresnel lens.

[0044] Figure 6 is a diagram illustrating the function of the polarization diffraction lens 51. Figure 6In FIG. 1 , the first region AR1 shows a first operation example of the first type polarization diffraction lens GP1, and the second region AR2 shows a second operation example of the first type polarization diffraction lens GP1. Figure 6 , the third area AR3 shows a first operation example of the second type polarization diffraction lens GP2 , and the fourth area AR4 shows a second operation example of the second type polarization diffraction lens GP2 . Figure 2 The polarization diffraction lens 51 shown in FIG. 1 is a second type of polarization diffraction lens GP2 .

[0045] The polarization diffraction lens GP1 has the following functions: when collimated second circularly polarized light, i.e., right circularly polarized light RCP, such as the solid line light ray L1, is incident from the left side of the figure, the polarization diffraction lens GP1 converts the right circularly polarized light RCP into the first circularly polarized light, i.e., left circularly polarized light LCP, and converges the light to focus at the focal point FP. When collimated left circularly polarized light LCP, such as the solid line light ray L1, is incident from the left side of the figure, the polarization diffraction lens GP1 converts the left circularly polarized light LCP into right circularly polarized light RCP and diverges the light. Furthermore, when right circularly polarized light RCP is incident, such as the double-dashed line light ray L2, which diverges from the focal point FP' on the left side of the figure, the polarization diffraction lens GP1 converts the right circularly polarized light RCP into left circularly polarized light LCP and collimates the light. In other words, the polarization diffraction lens GP1 functions like a positive lens with a predetermined focal length with respect to the right circularly polarized light RCP, and reverses the direction of rotation of the polarized light. Furthermore, the polarization diffraction lens GP1 functions as a negative lens with the same absolute value of focal length with respect to the left circularly polarized light LCP, and reverses the direction of rotation of the polarized light. In other words, the polarization diffraction lens GP1 is an optical element that has positive refractive power for the right circularly polarized light RCP and negative refractive power for the left circularly polarized light LCP.

[0046] The polarization diffraction lens GP2 has the following function: when collimated second circularly polarized light, i.e., right-handed circularly polarized light RCP, such as the light ray L1 shown as a solid line, is incident from the left side of the drawing, the polarization diffraction lens GP2 converts the right-handed circularly polarized light RCP into the first circularly polarized light, i.e., left-handed circularly polarized light LCP, and diverges it. The polarization diffraction lens GP2 has the following function: when collimated left-handed circularly polarized light LCP, such as the light ray L1 shown as a solid line, is incident from the left side of the drawing, the polarization diffraction lens GP2 converts the left-handed circularly polarized light LCP into right-handed circularly polarized light RCP, and converges the left-handed circularly polarized light LCP to focus at a focal point FP. In other words, the polarization diffraction lens GP2 functions like a positive lens of a predetermined focal length with respect to the left-handed circularly polarized light LCP, and reverses the direction of polarization rotation. Furthermore, the polarization diffraction lens GP2 functions like a negative lens of the same absolute focal length with respect to the right-handed circularly polarized light RCP, and reverses the direction of polarization rotation. In other words, the polarization diffraction lens GP2 is an optical element that has negative refractive power for right-handed circularly polarized light RCP and positive refractive power for left-handed circularly polarized light LCP.

[0047] Polarization diffraction lenses GP1 and GP2 have a refractive index anisotropy distribution within a plane, organized into multiple annular bands centered around the optical axis AX. Based on this refractive index anisotropy distribution and the polarization state of the incident light, they function as diffraction lenses. Specifically, if polarization diffraction lenses GP1 and GP2 have a refractive index anisotropy distribution such that the orientation of the optical axis rotates more with distance from the optical axis AX in two directions perpendicular to the central optical axis AX and mutually perpendicular to each other (actually repeating within a range of 0 to π), a geometric phase is formed on specific circularly polarized light incident thereon, causing diffraction of the circularly polarized light in each direction at a diffraction angle that reflects the period length of the rotation of the optical axis, thereby inverting the polarization state. As a whole, the polarization diffraction lens diffracts specific circularly polarized light in accordance with the refractive power formed by the lens shape, and the state of the circularly polarized light is inverted before and after passage, for example, from right-handed circularly polarized light to left-handed circularly polarized light.

[0048] Although not shown in the figure, polarizing diffraction lens GP1 and polarizing diffraction lens GP2 are lenses with a thin layer of liquid crystal material formed on a transparent substrate, and are generally thin plate-shaped. The liquid crystal material layer contains a predetermined liquid crystal material. The orientation axes of the liquid crystal molecules are aligned parallel to the X direction in the vicinity of the optical axis AX, for example. As they move away from the optical axis AX, they gradually rotate within the XY plane, based on the distance or radius centered on the optical axis AX, to form an initial geometric phase. In other words, the rotation angle of the orientation axis of the liquid crystal molecules increases with the distance from the optical axis AX, and this cycle repeats cyclically. In the liquid crystal compound layer, the orientation axes of the liquid crystal molecules remain uniformly aligned, for example, in the Z direction parallel to the optical axis AX. Furthermore, in polarizing diffraction lens GP1 and polarizing diffraction lens GP2, the direction in which the rotation angle of the orientation axis of the liquid crystal molecules increases is reversed. For example, the polarization diffraction lenses GP1 and GP2 are manufactured by applying a liquid crystal material film containing a mixture of a liquid crystal material and a UV-curable organic material layer onto a substrate. A UV laser with a predetermined polarization state is then two-dimensionally scanned across the liquid crystal material film, thereby adjusting the alignment axis of the liquid crystal molecules while curing the organic material layer. This allows the alignment axis of the liquid crystal molecules in the liquid crystal 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 with distance from the optical axis AX, as described above. Such a polarization diffraction lens GP1 itself, for example, as a polarization-dependent liquid crystal Fresnel lens, is well known (e.g., see Kohei Noda et al., Applied Optics, February 10, 2017, Vol. 56, No. 5:1302).

[0049] The polarization diffraction lenses GP1 and GP2 can also be produced by the method for producing a liquid crystal optical body described in Japanese Patent Application Publication No. 2008-501147.

[0050] Polarization diffraction lens GP1 and polarization diffraction lens GP2 do not need to be separate lenses. Polarization diffraction lens GP1 can be rotated 180° about the Y axis and reversed to form polarization diffraction lens GP2. That is, by reversing the positive and negative positions of polarization diffraction lenses GP1 and GP2, they can function as both positive and negative lenses for the same circularly polarized light. The reason for this is that, as described above, the alignment axes of the liquid crystal molecules in polarization diffraction lenses GP1 and GP2 rotate in a specific direction according to the distance centered on the optical axis AX. Therefore, the rotation direction relative to the absolute value of the distance, for example, in the ±X directions perpendicular to the optical axis AX, is consistent. When viewing each polarization diffraction lens GP1 or GP2 from the reverse side, the rotation direction of the alignment axis is reversed.

[0051] The focal lengths of polarizing diffraction lenses GP1 and GP2 can be adjusted based on the manufacturing method and liquid crystal material. For example, by increasing the rate of increase of the rotation angle relative to the distance from the optical axis AX or radius, i.e., by reducing the period of rotation of the alignment axis, the rotation angle of the liquid crystal molecules in the liquid crystal compound layer increases as the distance from the optical axis AX increases. This increases the absolute value of the positive or negative refractive power of polarizing diffraction lenses GP1 and GP2, allowing for focal length adjustment. When passing through polarizing diffraction lenses GP1 and GP2, the loss of circularly polarized light ray L1 is close to zero, and polarizing diffraction lenses GP1 and GP2 exhibit nearly 100% transmittance.

[0052] When linearly polarized light enters the polarization diffraction lens GP1, the right-handed circularly polarized light (RCP) and left-handed circularly polarized light (LCP) contained within the linearly polarized light behave differently. The right-handed circularly polarized light (RCP) component is focused by the polarization diffraction lens GP1, while the left-handed circularly polarized light (LCP) component is diverged by the polarization diffraction lens GP1, with the rotational directions of the polarized light reversed.

[0053] In the imaging system 50, the polarization diffraction lens 51 is Figure 6 The polarization diffraction lens GP2 shown in FIG. 2 functions as an optical element having positive refractive power for the image light ML incident from the display 40 when the image light ML is left-circularly polarized light LCP. This reduces the divergence of the image light ML and reverses the direction of polarization to convert it into right-circularly polarized light RCP. The image light ML, having passed through the polarization diffraction lens 51, enters the auxiliary lens 52 as right-circularly polarized light RCP.

[0054] When the external light OL is right-handed circularly polarized light (RCP), the polarization diffraction lens 51 functions as an optical element having negative refractive power for the external light OL, reducing the degree of convergence of the external light OL and reversing the direction of polarization to produce left-handed circularly polarized light (LCP). The external light OL that has passed through the polarization diffraction lens 51 enters the auxiliary lens 52 as left-handed circularly polarized light (LCP).

[0055] The auxiliary lens 52 functions as an optical element with positive refractive power for the image light ML, maintaining the polarization direction of the polarized light as right-handed circularly polarized light (RCP) and reducing divergence. At this point, the absolute values ​​of the refractive power of the polarization diffraction lens 51 and the auxiliary lens 52 are set equal. The combined focal length of the two lenses 51 and 52, i.e., the polarization-selective lens 50a, is approximately equivalent to the combined focal length of the two adjacent convex lenses. When the combined focal length of the polarization-selective lens 50a is equal to the distance from the midpoint between the two lenses 51 and 52 to the display surface of the monitor 40, the imaging system 50 functions as a collimator, collimating the image light ML and focusing it at the pupil position.

[0056] The auxiliary lens 52 functions as an optical element with positive refractive power for the external light OL, maintaining the polarization direction of the polarized light as left circularly polarized light LCP and reducing its divergence. At this point, the two lenses 51 and 52 are positioned close together, and their absolute refractive powers are set to be equal. This results in the combined focal length of the two lenses 51 and 52, i.e., the polarization-selective lens 50a, being infinite. When the combined focal length of the polarization-selective lens 50a is infinite, the imaging system 50 functions as an optical system with approximately zero refractive power, i.e., a parallel plate. This prevents the external light OL from being subjected to an imaging effect such as focusing, but instead allows it to travel approximately straight, enabling the naked eye to observe the external light OL.

[0057] The second display optical system 103b is optically identical to the first display optical system 103a, or is a system obtained by left-right inversion of the first display optical system 103a, and detailed description thereof is omitted.

[0058] In the first virtual image display apparatus 100A, the optical device other than the control device 80 is referred to as an optical unit 100 . In the second virtual image display apparatus 100B, the optical device other than the control device 80 is referred to as an optical unit 100 .

[0059] Figure 7 1 is a diagram illustrating the state of light in the first display optical system 103a. Figure 7 In FIG, the first region BR1 shows the state of the image light ML, and the second region BR2 shows the state of the external light OL.

[0060] During image observation, image light ML is emitted from the light-emitting area 25a of the image display panel 25. The image light ML emitted from the image display panel 25 includes the first polarized light P1 as longitudinal polarized light and the second polarized light P2 as transverse polarized light. The image light ML emitted from the image display panel 25 is incident on the pattern polarizing element 26. The image light ML passes through the first polarizing element 26a in the pattern polarizing element 26 and is limited to the first polarized light P1. The image light ML that has passed through the pattern polarizing element 26 is converted from the first polarized light P1 to left circularly polarized light LCP by the 1 / 4 wavelength plate 23. The imaging system 50 becomes in a state of having a positive refractive power for the image light ML of the left circularly polarized light LCP, and can observe the image light ML.

[0061] On the other hand, during external light observation, external light OL passes through the transmission area 25b of the image display panel 25 and is incident on the patterned polarizer 26. The external light OL passes through the second polarizer 26b in the patterned polarizer 26 and is limited to the second polarized light P2. The external light OL that has passed through the patterned polarizer 26 is converted from the second polarized light P2 to right-handed circularly polarized light RCP by the quarter-wave plate 23. The imaging system 50 is in a state where the refractive power of the external light OL, which is the right-handed circularly polarized light RCP, is substantially zero, enabling observation of the external light OL.

[0062] The virtual image display device 100A or the display optical system 103 a that performs the above-described display can perform a see-through display in which the image light ML and the external light OL are superimposed.

[0063] In the above description, a display 40 incorporating a transmissive liquid crystal panel 22 is used. However, other types of imagers 2a, such as organic EL (Organic Electro-Luminescence) displays, can also be used in place of the transmissive liquid crystal panel 22. However, it is preferred that the imager 2a of the organic EL display block external light OL while displaying an image and transmit external light OL while not displaying an image. In this case, a polarizing plate is preferably provided on the light-emitting side of the organic EL display serving as the imager 2a.

[0064] In the above description, the image display panel 25 has been described as having sub-pixels of three colors. However, when the color difference of the imaging system 50 is large, the imager 2 a or the image display panel 25 may be composed of only pixels of a single color.

[0065] The virtual image display device 100A, 100B or the optical unit 100 of the first embodiment described above includes: a display 40 that emits image light ML; and a polarization selection lens 50a that is arranged opposite to the display 40 and has a refractive power that selectively acts on the polarized light serving as the image light ML. The polarization selection lens 50a includes, from the display 40 side, a polarization diffraction lens 51 that has a positive refractive power for the image light ML serving as circularly polarized light and a negative refractive power for the external light OL serving as circularly polarized light; and an auxiliary lens 52 that has the same positive refractive power as the polarization diffraction lens 51.

[0066] In the virtual image display devices 100A and 100B described above, the polarizing diffraction lens 51 has positive refractive power for the circularly polarized image light ML from the display 40, and the auxiliary lens 52 has positive refractive power for the circularly polarized image light ML that has passed through the polarizing diffraction lens 51. Therefore, even when the display 40 is positioned in front of the eye, the image formed on the display surface of the display 40 can be observed using the thin imaging system 50 with a shortened focal length. In other words, the virtual image display devices 100A and 100B including the imaging system 50 can be made thinner. Furthermore, the polarizing diffraction lens 51 has negative refractive power for the circularly polarized external light OL, and the auxiliary lens 52 has positive refractive power for the circularly polarized external light OL that has passed through the polarizing diffraction lens 51, thereby canceling the refractive power of the polarizing diffraction lens 51. This allows the external light OL to be observed.

[0067] Second embodiment

[0068] Hereinafter, a virtual image display device according to a second embodiment will be described. The virtual image display device according to the second embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of the parts common to the virtual image display device according to the first embodiment will be omitted.

[0069] exist Figure 8 In the illustrated virtual image display device 100A or optical unit 100, the polarization selective lens 50a includes a polarization diffraction lens 51 and an auxiliary lens 52. The polarization diffraction lens 51 and the auxiliary lens 52 can be arranged in a bonded state. The polarization selective lens 50a comprises an array of thin plate-shaped lenses 51 and 52, thereby enabling the imaging system 50 to be thinned.

[0070] In this embodiment, the auxiliary lens 52 is a diffractive lens 52b. The diffractive lens 52b is a flat plate-shaped phase modulation lens that does not depend on the kinoform of polarized light. The diffractive lens 52b is, for example, a Fresnel zone plate or a liquid crystal lens.

[0071] Third embodiment

[0072] Hereinafter, a virtual image display device according to a third embodiment will be described. The virtual image display device according to the third embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of the parts common to the virtual image display device according to the first embodiment will be omitted.

[0073] exist Figure 9 In the illustrated virtual image display device 100A or optical unit 100, the display 40 includes an image display panel 25, a polarizing half mirror 60, and a quarter-wave plate 23. The quarter-wave plate 23 is disposed close to the incident side of the imaging system 50. In this embodiment, the polarizing half mirror 60 functions as the polarization separation element 41.

[0074] The polarizing half mirror 60 is arranged between the image display panel 25 and the imaging system 50 so as to reflect the image light ML from the image display panel 25 toward the imaging system 50. The polarizing half mirror 60 reflects polarized light in a predetermined direction, selectively reflecting the image light ML from the image display panel 25 while transmitting the external light OL. The polarizing half mirror 60 includes a polarization separation film 61 on one surface 60s of a light-transmitting substrate 60a. The polarization separation film 61 reflects, for example, the first polarized light P1 in the image light ML and transmits, for example, the second polarized light P2 in the external light OL. The polarization separation film 61 is formed of a dielectric multilayer film. The polarization separation film 61 only needs to selectively reflect the image light ML according to the polarization direction and can be formed, for example, from a wire-grid polarizer. The polarizing half mirror 60 can also form an anti-reflection film on the other surface 60t of the substrate 60a. The polarization half mirror 60 can be either a flat surface or a curved surface.

[0075] The polarizing half mirror 60 is tilted with respect to the vertical direction or the Y direction perpendicular to the arrangement direction of the eyes EY. The tilt angle of the polarizing half mirror 60 is, for example, 45°, but may not be 45°.

[0076] The imaging system 50 is a polarization selective lens 50a, which includes a polarization diffraction lens 51 and an auxiliary lens 52. As the polarization diffraction lens 51, a polarization diffraction lens 51 is used. Figure 6 The auxiliary lens 52 can be either Figure 9 The refractive lens 52a shown can also be Figure 8 The diffractive lens 52b is shown.

[0077] In this embodiment, the patterned polarizing element 26 is not provided. Therefore, in the image display panel 25, the plurality of light-emitting regions 25a are arranged in a matrix as a whole.

[0078] Fourth embodiment

[0079] Hereinafter, a virtual image display device according to a fourth embodiment will be described. The virtual image display device according to the fourth embodiment is a partially modified version of the virtual image display device according to the first embodiment, and description of the common parts with the virtual image display device according to the first embodiment will be omitted.

[0080] exist Figure 10 In the illustrated virtual image display device 100A or optical unit 100, the display 40 includes an image display panel 25, a light guide member 70, and a quarter-wave plate 23. The quarter-wave plate 23 is disposed close to the incident side of the imaging system 50. In this embodiment, a polarizing half mirror 75 of the light guide member 70, described later, functions as the polarization separation member 41.

[0081] The light guide member 70 is a member that is generally in the shape of a parallel flat plate and includes a first prism 71 and a second prism 72. The first prism 71 and the second prism 72 are joined at inclined surfaces 71a and 72a. A polarization separation film 73 is formed on the inclined surface 71a of the first prism 71, and functions as a polarization half-mirror 75 in the light guide member 70. Similar to the polarization half-mirror 60 of the third embodiment, the polarization half-mirror 75 reflects polarized light in a predetermined direction, selectively reflects the image light ML from the image display panel 25, and transmits the external light OL. The image light ML emitted from the light guide member 70 is, for example, the first polarized light P1. Furthermore, the external light OL emitted from the light guide member 70 is, for example, the second polarized light P2.

[0082] The first prism 71 has a convex surface 70a on the surface facing the image display panel 25, which serves as the incident surface for the image light ML. The first prism 71 guides the image light ML incident from the image display panel 25. The first prism 71 has an inner side surface 71b and an outer side surface 71c, which are parallel to the quarter-wave plate 23 disposed on the emission side. The image light ML incident on the first prism 71 is totally reflected by the outer side surface 71c and the inner side surface 71b, and then reflected by the polarizing half mirror 75 as the first polarized light P1, which is then emitted from the light guide member 70.

[0083] The second prism 72 is disposed below the first prism 71 via a polarization separation film 73. The second prism 72 transmits the external light OL. The external light OL incident on the second prism 72 is transmitted through the polarization half mirror 75 as second polarized light P2 and is emitted from the light guide member 70.

[0084] The first prism 71 and the second prism 72 are made of resin or glass, and are formed of a low-birefringence material. By reducing the birefringence of the light guide member 70, polarization variations caused by birefringence within the light guide member 70 can be suppressed. This prevents the lens action of the polarization diffraction lens 51 of the imaging system 50 from varying within the image plane and causing unevenness.

[0085] The imaging system 50 is a polarization selective lens 50a, which includes a polarization diffraction lens 51 and an auxiliary lens 52. As the polarization diffraction lens 51, a polarization diffraction lens 51 is used. Figure 6 The auxiliary lens 52 can be either Figure 10 The refractive lens 52a shown can also be Figure 8 The diffractive lens 52b is shown.

[0086] In this embodiment, the patterned polarizing element 26 is not provided. Therefore, in the image display panel 25, the plurality of light-emitting regions 25a are arranged in a matrix as a whole.

[0087] Fifth embodiment

[0088] Hereinafter, a fifth embodiment of the virtual image display device will be described. The fifth embodiment of the virtual image display device is a partially modified version of the first embodiment of the virtual image display device, and descriptions of portions common to the first embodiment of the virtual image display device will be omitted.

[0089] Figure 11 It is a schematic perspective view for explaining the structure of the first display optical system 103a of the first virtual image display device 100A. Figure 12 It is a schematic side cross-sectional view illustrating the structure of the display 40 .

[0090] The display 40 includes a light source 10 that generates three-color light as illumination light in a time-division manner, and a composite display component 20 that forms and emits image light ML. The light source 10 is also Figure 1 A portion of the first display drive unit 102a shown is positioned near the upper side of the light guide member 21, so as to supply illumination light from the upper edge to the light guide member 21 (described later) within the composite display member 20. The composite display member 20 of the display 40 is positioned close to the eye EY, with the imaging system 50 interposed therebetween, enabling observation of a virtual image based on image light ML and perspective observation of the outside world. In the first display optical system 103a, the distance between the eye EY and the imaging system 50 in the direction of the optical axis AX is, for example, approximately 10 mm to 20 mm. Furthermore, the distance between the transmissive liquid crystal panel 22 of the display 40 and the imaging system 50 in the direction of the optical axis AX is, for example, approximately 5 mm to 25 mm.

[0091] The light source 10 includes one or more R light-emitting elements 10r that generate red light, one or more B light-emitting elements 10b that generate blue light, and one or more G light-emitting elements 10g that generate green light. The R light-emitting elements 10r, B light-emitting elements 10b, and G light-emitting elements 10g are self-luminous elements, such as organic light-emitting diodes (OLEDs), but may also be light-emitting diodes such as micro-light-emitting diodes (μLEDs) formed from inorganic materials. A wavelength combiner / demultiplexer including a beam splitter to assist in the diffusion of illumination light can be incorporated between the light source 10 and the light guide component 21 of the composite display component 20.

[0092] The composite display component 20 is a plate-shaped component extending along the XY plane perpendicular to the optical axis AX, and comprises a light guide component 21, a transmissive liquid crystal panel 22 and a quarter wavelength plate 23 in order from the outside. The composite display component 20 has a structure in which the light guide component 21, the transmissive liquid crystal panel 22 and the quarter wavelength plate 23 are stacked together by a frame (not shown). Here, the light guide component 21 and the transmissive liquid crystal panel 22 are arranged close to each other with a prescribed interval or less. The transmissive liquid crystal panel 22 is an imager 2a that forms the image light ML. In addition, the transmissive liquid crystal panel 22 includes a plurality of pixels PX (refer to FIG. 1 ) arranged in a matrix along the XY plane. Figure 12 ).

[0093] Furthermore, a polarizing plate 27 (see FIG. 2 ) is provided on the external side of the light guide member 21 to limit polarized light as the external light OL. Figure 12 ).

[0094] The light source 10 and the light guide member 21 function as a backlight LL. In this embodiment, the backlight LL and the transmissive liquid crystal panel 22 (including the patterned polarizing element 26 described later) function as a polarization separation member 41 that imparts different polarization components to the image light ML and the external light OL.

[0095] The imaging system 50 is arranged on the face side, i.e., the -Z side, relative to the display 40 or the composite display unit 20, and covers the front of the eye. The imaging system 50 includes a polarization selective lens 50a. The polarization selective lens 50a includes a polarization diffraction lens 51 and an auxiliary lens 52 in this order from the outside or the display 40 side.

[0096] Reference Figure 12 The light source 10 generates three-color illumination lights ILr, ILg, and ILb from the light emitting elements 10 r , 10 g , and 10 b as illumination light IL, and supplies the three-color illumination lights ILr, ILg, and ILb to the light guide member 21 of the composite display member 20 .

[0097] The light guide member 21 is a member in which the ferroelectric liquid crystal panel 12 is fixed to the light guide plate 11. The illumination lights ILr, ILg, and ILb from the light source 10 are coupled into the light guide plate 11 from the upper end thereof. The light guide plate 11 propagates the illumination lights ILr, ILg, and ILb incident from the light source 10 downward.

[0098] The ferroelectric liquid crystal panel 12 is a device that performs switching operations based on a drive signal from the drive circuit 81. It can switch between a scattering state (on state) in which the illumination light IL (ILr, ILg, ILb) is emitted out of the light guide plate 11, and a transparent state (off state) in which the external light OL is transmitted and allowed to pass. The ferroelectric liquid crystal panel 12 includes a ferroelectric liquid crystal layer 12a sandwiched between a pair of substrates 12b and 12c via a transparent electrode layer (not shown). The ferroelectric liquid crystal layer 12a is, for example, a reverse-mode polymer-dispersed liquid crystal, which is in a transmissive state when no electric field is applied and in a scattering state when an electric field is applied (see, for example, Japanese Patent Application Laid-Open No. 6-308543). The ferroelectric liquid crystal panel 12 can be switched on and off for the entire surface, not on a pixel PX basis. Furthermore, the ferroelectric liquid crystal layer 12a can also be in a transmissive state when an electric field is applied and in a scattering state when no electric field is applied.

[0099] Furthermore, a scattering member for scattering the image light ML may be provided on the light guide plate 11 instead of the ferroelectric liquid crystal panel 12 .

[0100] The transmissive liquid crystal panel 22 has a liquid crystal modulation component 14 and a pair of polarizing plates 15 and 16 sandwiching the liquid crystal modulation component 14. In this case, the transmissive liquid crystal panel 22 is, for example, a modulation element composed of IPS (in plane switching) type liquid crystal, and has image light generating pixels PX (C) and external light transmitting pixels PX (T). The image light generating pixels PX (C) and the external light transmitting pixels PX (T) are arranged alternately. The liquid crystal modulation component 14 does not rotate the polarization direction of the incident light when no electric field is applied, and rotates the polarization direction of the incident light when an electric field is applied. In this case, the pair of polarizing plates 15 and 16 are absorption-type polarizing elements. The polarizing plate 16 and Figure 5 The patterned polarizing elements 26 shown are identical.

[0101] The transmissive liquid crystal panel 22 can be switched on and off on a pixel-by-pixel basis based on a drive signal from the drive circuit 81, allowing incident light to partially pass through at any grayscale intermediate between on and off. Therefore, the liquid crystal modulation element 14 includes not only a liquid crystal layer 31, a common electrode 32, pixel electrodes 33, and a black matrix 35, but also scan lines, signal lines, switching elements, and the like (not shown).

[0102] Furthermore, the transmissive liquid crystal panel 22 or the liquid crystal modulation element 14 may rotate the polarization direction of the incident light when no electric field is applied, and may not rotate the polarization direction of the incident light when an electric field is applied.

[0103] Figure 13 40 is a diagram illustrating the state of light in the display 40. Figure 13 , the first region CR1 shows the case where the first display optical system 103a is in the image observation period and the display 40 is in the display state. The second region CR2 shows the case where the first display optical system 103a is in the ambient light observation period and the display 40 is in the non-display state.

[0104] During the image observation period, when the display 40 is in the display state, the light-emitting elements 10r, 10g, and 10b of the light source 10 emit light, supplying illumination light ILr, ILg, and ILb to the light guide member 21. At this timing, when the ferroelectric liquid crystal panel 12 is switched to the on state (the first state) and enters the scattering state, the illumination light ILr, ILg, and ILb passes through the first polarizer 15 of the transmissive liquid crystal panel 22 and illuminates the liquid crystal modulator 14 as transversely polarized light or horizontally polarized light, namely, second polarized light P2. In other words, the image light generating pixels PX(C) constituting the transmissive liquid crystal panel 22 are illuminated. The image light ML(R), ML(G), and ML(B) that pass through the liquid crystal modulator 14 have their polarization planes rotated according to the drive signal. After passing through the second polarizer 16, only the first polarized light P1, which is longitudinally polarized light or vertically polarized light, is emitted. The image lights ML(R), ML(G), and ML(B) emitted from the image light generating pixels PX(C) of the transmissive liquid crystal panel 22 are converted from the first polarized light P1 to the left circularly polarized light LCP through the quarter-wave plate 23 .

[0105] On the other hand, during the external light observation period, when the display 40 is in the non-display state, the light source 10 is turned off, and the supply of illumination light IL to the light guide member 21 is stopped. At this timing, when the ferroelectric liquid crystal panel 12 is switched to the off state (the second state), becoming a transmissive state, the external light OL travels straight across the light guide member 21, intersecting the light guide member 21 and entering the transmissive liquid crystal panel 22. At this time, the external light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 operate, for example, in the normally-off state and enter the maximum transmissive state in response to a drive signal. The second polarized light P2 of the external light OL incident on the external light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 travels straight through the external light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 and is emitted. The external light OL emitted from the external light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 passes through the quarter-wave plate 23, converting the second polarized light P2 into right circularly polarized light RCP.

[0106] During the image observation period, the imaging system 50 has a positive refractive power and can observe the image light ML. During the external light observation period, the imaging system 50 has a substantially zero refractive power and can observe the external light OL.

[0107] Figure 14 This is a timing chart illustrating the display operation of the display optical system 103a. The horizontal axis represents time, and, from the top, shows the scintillation signal SS1 for the R light-emitting element 10r, the R drive signal SM1 for red display supplied to the liquid crystal modulation element 14, the scintillation signal SS2 for the G light-emitting element 10g, the G drive signal SM2 for green display supplied to the liquid crystal modulation element 14, the scintillation signal SS3 for the B light-emitting element 10b, the B drive signal SM3 for blue display supplied to the liquid crystal modulation element 14, and the on / off signal SD for the ferroelectric liquid crystal panel (FLC) 12. The operation of the first virtual image display device 100A includes, in each frame, a first subframe Z1 for image observation and a second subframe Z2 for ambient light observation.

[0108] In this case, when the first virtual image display device 100A is in the image observation period and the transmissive liquid crystal panel 22 is in the display state, the three-color image light ML(R), ML(G), and ML(B) are displayed in a time-division manner. When the first virtual image display device 100A is in the external light observation period and the transmissive liquid crystal panel 22 is in the non-display state, the external light OL passes through the external light-transmitting pixel PX(T) of the transmissive liquid crystal panel 22.

[0109] Sixth embodiment

[0110] The following describes a sixth embodiment of a virtual image display device, etc. The sixth embodiment of the virtual image display device is a partially modified version of the first and fifth embodiments of the virtual image display device, and descriptions of portions common to the first embodiment of the virtual image display device, etc., are omitted.

[0111] Figure 15 1 is a schematic side cross-sectional view illustrating the structure of the first display optical system 103a and the state of light. Figure 15 , the first region DR1 shows the case where the first display optical system 103a is in the image observation period and the display 40 is in the display state. The second region DR2 shows the case where the first display optical system 103a is in the external light observation period and the display 40 is in the non-display state.

[0112] The display 40 includes a light source 10 that generates three-color light as illumination light in a time-division manner, and a composite display component 20 that forms and emits image light ML.

[0113] The composite display unit 20 includes a light guide unit 21, a transmissive liquid crystal panel 22, and a quarter-wave plate 23 in this order from the outside. Furthermore, the composite display unit 20 includes a time-division half-wave plate 28 formed by sandwiching the transmissive liquid crystal panel 22 with a pair of liquid crystal wavelength plates 28a and 28b. The transmissive liquid crystal panel 22 is an imager 2a that forms the image light ML. The second polarizing plate 16 on the emission side of the transmissive liquid crystal panel 22 of this embodiment is not Figure 5 The patterned polarizing element 26 shown is an element that limits the light passing therethrough to light of a specific polarization, for example, the first polarized light P1.

[0114] In this embodiment, the pixels PX of the transmissive liquid crystal panel 22 are not limited to being composed of color units, but may be composed of sub-pixels of three colors, RGB, and a sub-pixel for transmitting external light OL. In this case, a color filter is provided in the sub-pixel for image light ML.

[0115] Furthermore, a polarizing plate 27 for limiting polarized light serving as external light OL is provided on the external side of the light guide member 21 .

[0116] The light source 10 and the light guide member 21 function as a backlight LL. In this embodiment, the backlight LL, the transmissive liquid crystal panel 22, and the time-division half-wave plate 28 function as a polarization separation member 41 that imparts different polarization components to the image light ML and the external light OL.

[0117] In addition, the backlight source LL may be a laser light source or the like.

[0118] The time division 1 / 2 wavelength plate 28 is based on Figure 1 The device shown in FIG. 1 is a device that switches the polarization direction of incident light between a first polarization direction and a second polarization direction that intersect each other, depending on the orientation of the liquid crystal. The time-division half-wave plate 28 comprises a first liquid crystal wave plate 28a and a second liquid crystal wave plate 28b. The first and second liquid crystal wave plates 28a and 28b can be switched on and off, not on a pixel-by-pixel basis, but across the entire surface. When the time-division half-wave plate 28 is in its first, off, state, it functions as a transparent plate, allowing image light ML to pass through while maintaining its polarization direction. On the other hand, when the time-division half-wave plate 28 is in its second, on, state, it functions as a half-wave plate with a principal axis midway between the X and Y directions, rotating the polarization direction of external light OL by 90°.

[0119] The first and second liquid crystal wave plates 28a, 28b that comprise the time-division half-wavelength plate 28 include liquid crystal layers sandwiched between a pair of substrates with transparent electrode layers interposed therebetween. The liquid crystal layers are, for example, IPS (in plane switching) liquid crystals. When an electric field is applied, the first and second liquid crystal wave plates 28a, 28b function as optical elements equivalent to half-wavelength plates with a major axis or fast axis defined in a specific direction (e.g., between the X and Y directions). When no electric field is applied, the first and second liquid crystal wave plates 28a, 28b function as isotropic parallel plates.

[0120] During image observation, i.e., when image light ML is incident, the half-wave plate 28 is in the off state (a first state), maintaining its original polarization state. During external light observation, i.e., when external light OL is incident, the half-wave plate 28 is in the on state (a second state), switching its polarization state.

[0121] During the image observation period, when the display 40 is in the display mode, the light-emitting elements 10r, 10g, and 10b of the light source 10 emit light, supplying illumination light ILr, ILg, and ILb to the light guide member 21. At this timing, when the ferroelectric liquid crystal panel 12 switches to the on state and enters the scattering state, the illumination light ILr, ILg, and ILb maintain their original polarization state while passing through the first liquid crystal wave plate 28a of the time-division half-wave plate 28, which is in the off state. The illumination light ILr, ILg, and ILb then passes through the first polarizing plate 15 of the transmissive liquid crystal panel 22 and illuminates the liquid crystal modulator 14 as transversely polarized light, or horizontally polarized light, or second polarized light P2. The image light ML(R), ML(G), and ML(B) that passes through the liquid crystal modulator 14 has its polarization plane rotated according to the drive signal. After passing through the second polarizing plate 16 and the second liquid crystal wave plate 28b of the time-division half-wave plate 28, only the first polarized light P1, which is longitudinally polarized light or vertically polarized light, is emitted. The image lights ML(R), ML(G), and ML(B) emitted from the pixels of the transmissive liquid crystal panel 22 pass through the quarter-wave plate 23 and are converted from the first polarized light P1 to the left circularly polarized light LCP.

[0122] On the other hand, during the external light observation period, when the display 40 is in the non-display state, the light source 10 is turned off, and the supply of illumination light IL to the light guide member 21 is stopped. At this timing, when the ferroelectric liquid crystal panel 12 switches to the second state (off), becoming a transmissive state, external light OL travels straight across the light guide member 21, intersecting the light guide member 21 and entering the first liquid crystal wave plate 28a of the time-division half-wave plate 28. At this time, the external light OL is converted from the first polarized light P1 to the second polarized light P2 by the first liquid crystal wave plate 28a of the time-division half-wave plate 28, which is in the on state. The external light OL that has passed through the first liquid crystal wave plate 28a enters the transmissive liquid crystal panel 22. The external light OL that has passed through the liquid crystal modulator 14 has its polarization plane rotated, and after passing through the second polarizing plate 16, only the first polarized light P1 is emitted as longitudinally polarized light or vertically polarized light. The external light OL is then converted from the first polarized light P1 to the second polarized light P2 by the second liquid crystal wave plate 28b of the time-division half-wave plate 28 in the on state. The external light OL emitted from the second liquid crystal wave plate 28b is converted from the second polarized light P2 to the right circularly polarized light RCP by the quarter-wave plate 23.

[0123] During the image observation period, the imaging system 50 has a positive refractive power and can observe the image light ML. During the external light observation period, the imaging system 50 has a substantially zero refractive power and can observe the external light OL.

[0124] Figure 16 This is a timing chart illustrating the display operation of the display optical system 103a. The horizontal axis represents time, and, from the top, shows, in order, the scintillation signal SS1 for the R light-emitting element 10r, the R drive signal SM1 for red display supplied to the liquid crystal modulation element 14, the scintillation signal SS2 for the G light-emitting element 10g, the G drive signal SM2 for green display supplied to the liquid crystal modulation element 14, the scintillation signal SS3 for the B light-emitting element 10b, the B drive signal SM3 for blue display supplied to the liquid crystal modulation element 14, the on / off signal SD for the ferroelectric liquid crystal panel (FLC) 12, and the on / off signal SW for the time-division half-wavelength plate (1 / 2λ) 28. The operation of the first virtual image display device 100A includes, in each frame, a first subframe Z1 for image observation and a second subframe Z2 for ambient light observation.

[0125] In this case, when the first virtual image display device 100A is in the image observation period and the transmissive liquid crystal panel 22 is in the display state, the three-color image light ML(R), ML(G), and ML(B) are displayed in a time-division manner. When the first virtual image display device 100A is in the external light observation period and the transmissive liquid crystal panel 22 is in the non-display state, the external light OL passes through the pixels of the transmissive liquid crystal panel 22, and the external image can be observed.

[0126] Modifications and others

[0127] While the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit and scope of the present invention. For example, the following modifications are also possible.

[0128] The display 40 and the composite display component 20 assembled therein are not limited to Figure 3 Various types of display panels can be used, such as the types shown as examples.

[0129] In the imaging system 50, the polarization diffraction lens 51 may also be Figure 6 The polarizing diffraction lens GP1 shown in FIG. In this case, the display 40 is configured such that the image light ML and the external light OL incident on the quarter-wave plate 23 become the second polarized light P2 and the first polarized light P1, respectively. When the image light ML incident from the display 40 is right-handed circularly polarized light RCP, the polarizing diffraction lens GP1 functions as an optical element having positive refractive power for the image light ML, reducing the divergence of the image light ML and reversing the rotation direction of the polarization to form left-handed circularly polarized light LCP. When the external light OL is left-handed circularly polarized light LCP, the polarizing diffraction lens GP1 functions as an optical element having negative refractive power for the external light OL, reducing the convergence of the external light OL and reversing the rotation direction of the polarization to form right-handed circularly polarized light RCP.

[0130] The above description assumes that the HMD 200 is worn on the head for use. However, the virtual image display devices 100A and 100B can also be used as handheld displays that are not worn on the head but viewed like binoculars. In other words, in the present invention, head-mounted displays also include handheld displays.

[0131] The virtual image display device in a specific embodiment includes: a display that emits image light; and a polarization selection lens that is arranged opposite to the display and has a refractive power that selectively acts on polarized light serving as image light. The polarization selection lens includes, starting from the display side: a polarization diffraction lens that has positive refractive power for image light serving as circularly polarized light and negative refractive power for external light serving as circularly polarized light; and an auxiliary lens that has the same positive refractive power as the polarization diffraction lens.

[0132] In the virtual image display device described above, the polarizing diffraction lens has positive refractive power for circularly polarized image light from the display, and the auxiliary lens has positive refractive power for the circularly polarized image light that has passed through the polarizing diffraction lens. Therefore, even if the display is positioned directly in front of the eye, the image formed on the display surface of the display can be observed using a thin imaging system with a shortened focal length. In other words, the virtual image display device including the imaging system can be made thinner. Furthermore, the polarizing diffraction lens has negative refractive power for circularly polarized external light, and the auxiliary lens has positive refractive power for circularly polarized external light that has passed through the polarizing diffraction lens, thereby canceling the refractive power of the polarizing diffraction lens, thereby enabling observation of the external light.

[0133] In a specific embodiment of a virtual image display device, the display includes a polarization separation element disposed on the display side of a polarization selective lens to impart different polarization components to image light and ambient light, and a quarter-wave plate to convert a predetermined linearly polarized light into a predetermined circularly polarized light. In this case, the image light emitted from the display can be circularly polarized.

[0134] In a specific embodiment of the virtual image display device, the polarization diffraction lens forms an anisotropic refractive index distribution within a plane, and generates a geometric phase corresponding to the lens shape with respect to predetermined circularly polarized light.

[0135] In a specific embodiment of the virtual image display device, the auxiliary lens has a refractive effect on the image light that has been converted from the first circularly polarized light to the second circularly polarized light by the polarization diffraction lens.

[0136] In a specific embodiment of a virtual image display device, a polarizing diffraction lens converts image light from left-circularly polarized light, which is the first circularly polarized light, to right-circularly polarized light, which is the second circularly polarized light, and converts external light from right-circularly polarized light, which is the second circularly polarized light, to left-circular polarized light, which is the first circularly polarized light. In this case, the polarizing diffraction lens converts the incident left-circularly polarized light, which is the image light, into right-circularly polarized light, and emits it in a relatively convergent state. Alternatively, the polarizing diffraction lens converts the incident right-circularly polarized light, which is the external light, into left-circular polarized light, and emits it in a relatively divergent state.

[0137] In a specific embodiment of the virtual image display device, the auxiliary lens is either a refractive lens or a diffractive lens.

[0138] In a specific embodiment of the virtual image display device, the refractive lens is either a convex lens or a Fresnel lens.

[0139] In a specific embodiment of the virtual image display device, the diffraction lens is either a Fresnel zone plate or a liquid crystal lens. In this case, the polarization selective lens can be made thinner.

[0140] In a specific embodiment of the virtual image display device, the polarization separation component is a polarization half mirror that reflects first polarization of a specific direction in the image light toward the polarization selective lens and transmits second polarization perpendicular to the first polarization in the external light.

[0141] In a specific embodiment of a virtual image display device, the polarized light separation components are an image display panel and a patterned polarization element. The image display panel has a luminous area for forming image light and a transmissive area for allowing external light to pass through. The patterned polarization element is arranged between the image display panel and the polarization selection lens, and has different polarization components in the luminous area and the transmissive area.

[0142] In a specific virtual image display device, the polarized light separation components are a backlight source, a liquid crystal panel, and a patterned polarization element. The liquid crystal panel has image light generating pixels and external light transmitting pixels. The patterned polarization element enables the image light generating pixels and the external light transmitting pixels to have different polarization components.

[0143] In a specific embodiment of a virtual image display device, the polarization separation component is a backlight source, a liquid crystal panel, a first liquid crystal wave plate, and a second liquid crystal wave plate. The first liquid crystal wave plate is arranged on the incident side of the liquid crystal panel, and the second liquid crystal wave plate is arranged on the emission side of the liquid crystal panel. When image light is emitted by the backlight source, the first polarized light in a specific direction is emitted when the first liquid crystal wave plate and the second liquid crystal wave plate are in a first state. When external light is emitted by the backlight source being extinguished, the second polarized light perpendicular to the first polarized light is emitted when the first liquid crystal wave plate and the second liquid crystal wave plate are in a second state.

[0144] The optical unit in the specific embodiment includes: a display that emits image light; and a polarization selection lens that is arranged opposite to the display and has a refractive power that selectively acts on polarized light serving as image light. The polarization selection lens includes, starting from the display side, a polarization diffraction lens that has positive refractive power for image light serving as circularly polarized light and negative refractive power for external light serving as circularly polarized light; and an auxiliary lens that has the same positive refractive power as the polarization diffraction lens.

Claims

1. A virtual image display device comprising: a display that emits image light; and a polarization selective lens disposed opposite to the display and having a refractive power that selectively acts on the polarized light serving as the image light; The polarization selection lens includes, in order from the display side: a polarization diffraction lens having positive refractive power for the image light as circularly polarized light and negative refractive power for external light as circularly polarized light; and an auxiliary lens having the same positive refractive power as the polarization diffraction lens.

2. The virtual image display device according to claim 1, wherein: The display has: a polarization separation component disposed on the display side of the polarization selective lens so that the image light and the external light have different polarization components; and A quarter-wave plate converts predetermined linearly polarized light into predetermined circularly polarized light.

3. The virtual image display device according to claim 1, wherein: The polarization diffraction lens forms an anisotropic refractive index distribution within a plane, and generates a geometric phase corresponding to the lens shape with respect to predetermined circularly polarized light.

4. The virtual image display device according to claim 1, wherein: The auxiliary lens has a refractive effect on the image light that has been converted from the first circularly polarized light to the second circularly polarized light after passing through the polarization diffraction lens.

5. The virtual image display device according to claim 4, wherein: The polarization diffraction lens changes the image light from left circularly polarized light as the first circularly polarized light to right circularly polarized light as the second circularly polarized light, and changes the external light from right circularly polarized light as the second circularly polarized light to left circularly polarized light as the first circularly polarized light.

6. The virtual image display device according to claim 1, wherein: The auxiliary lens is any one of a refractive lens and a diffractive lens.

7. The virtual image display device according to claim 6, wherein: The refractive lens is any one of a convex lens and a Fresnel lens.

8. The virtual image display device according to claim 6, wherein: The diffraction lens is any one of a Fresnel zone plate and a liquid crystal lens.

9. The virtual image display device according to claim 2, wherein: The polarization separation member is a polarization half mirror that reflects first polarized light of a specific direction in the image light toward the polarization selective lens and transmits second polarized light of the external light that is perpendicular to the first polarized light.

10. The virtual image display device according to claim 2, wherein: The polarized light separation component is an image display panel and a pattern polarization element. The image display panel has a luminous area that forms the image light and a transmissive area that allows the external light to pass through. The pattern polarization element is arranged between the image display panel and the polarization selection lens, and has different polarization components in the luminous area and the transmissive area.

11. The virtual image display device according to claim 2, wherein: The polarized light separation component is a backlight, a liquid crystal panel, and a patterned polarization element. The liquid crystal panel has image light generating pixels and external light transmitting pixels. The patterned polarization element enables the image light generating pixels and the external light transmitting pixels to have different polarization components.

12. The virtual image display device according to claim 2, wherein: The polarized light separation components are a backlight source, a liquid crystal panel, and a time-division 1 / 2 wavelength plate. The time division half-wave plate includes a first liquid crystal wave plate arranged on the incident side of the liquid crystal panel and a second liquid crystal wave plate arranged on the emission side of the liquid crystal panel. When the image light is emitted by the light of the backlight source, the first polarized light in a specific direction is emitted when the time-division 1 / 2 wavelength plate is in the first state; when the external light is emitted by the extinguishing of the backlight source, the second polarized light perpendicular to the first polarized light is emitted when the time-division 1 / 2 wavelength plate is in the second state.

13. An optical unit comprising: a display that emits image light; and a polarization selective lens disposed opposite to the display and having a refractive power that selectively acts on the polarized light serving as the image light; The polarization selection lens includes, in order from the display side: a polarization diffraction lens having positive refractive power for the image light as circularly polarized light and negative refractive power for external light as circularly polarized light; and an auxiliary lens having the same positive refractive power as the polarization diffraction lens.

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