Virtual image display device and optical unit

Abstract

To reduce the thickness of an image forming system of a virtual image display device.SOLUTION: A virtual image display device 100A (100B) or an optical unit 100 comprises: a display 40 that emits video light ML; and a polarization selection lens 50a that is arranged opposite to the display 40, and has a refractive power selectively acting on polarized light of the video light ML. The polarization selection lens 50a has, in order from the side of the display 40, a polarization diffraction lens 51 that has a positive refractive power to circularly polarized video light ML and has a negative refractive power to circularly polarized external light OL, and an auxiliary lens 52 that has a positive refractive power equivalent to that of the polarization diffraction lens 51.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable the observation of a virtual image, and more particularly to a virtual image display device that uses a polarized diffractive lens. [Background technology]

[0002] A polarization conversion system comprising a geometric phase element and a retarder element is known (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 retarder element is positioned to receive light output from the geometric phase element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-519327 Summary of the Invention [Problem to be solved by the invention]

[0004] The geometric phase element in the polarization conversion system has a focusing effect on right-handed circularly polarized light and a diverging effect on left-handed circularly polarized light. Therefore, simply applying the system of Patent Document 1 to a virtual image display device makes it difficult to achieve both video observation and ambient light observation. When creating a see-through virtual image display device, the geometric phase element must be positioned outside the see-through area, which creates the problem of an increased size of the optical system. [Means for solving the problem]

[0005] A virtual image display device and optical unit in one aspect of the present invention comprises a display that emits image light, and a polarization selection lens that is arranged opposite the display and has a refractive power that selectively acts on the polarization of the image light, and the polarization selection lens has, in order from the display side, a polarized diffractive lens that has a positive refractive power for circularly polarized image light and a negative refractive power for circularly polarized external light, and an auxiliary lens that has a positive refractive power equivalent to that of the polarized diffractive lens. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 2 is an external front view illustrating a wearing state of the virtual image display device of the first embodiment. [Figure 2] FIG. 1 is a conceptual perspective view illustrating a structure of a virtual image display device. [Figure 3] FIG. 2 is a conceptual side cross-sectional view illustrating the configuration of a display optical system. [Figure 4] FIG. 2 is a rear view illustrating the image display panel. [Figure 5] FIG. 2 is a rear view illustrating the patterned polarizing element. [Figure 6] 1A and 1B are diagrams illustrating the function of a polarized diffractive lens. [Figure 7] 3A and 3B are diagrams illustrating the state of light in a display optical system. [Figure 8] FIG. 10 is a conceptual side cross-sectional view illustrating a virtual image display device according to a second embodiment. [Figure 9] FIG. 10 is a conceptual side cross-sectional view illustrating a virtual image display device according to a third embodiment. [Figure 10] FIG. 10 is a conceptual side cross-sectional view illustrating a virtual image display device according to a fourth embodiment. [Figure 11] FIG. 10 is a conceptual perspective view illustrating the structure of a virtual image display device according to a fifth embodiment. [Figure 12] 12 is a conceptual side cross-sectional view illustrating the configuration of the display optical system in FIG. 11. FIG. [Figure 13] 12 is a diagram illustrating the state of light in the display optical system of FIG. 11. FIG. [Figure 14] 12 is a chart illustrating the operation of the virtual image display device of FIG. [Figure 15] FIG. 13 is a conceptual side cross-sectional view illustrating the configuration of a display optical system and the state of light in a virtual image display device according to a sixth embodiment. [Figure 16] 16 is a chart illustrating the operation of the virtual image display device of FIG. 15. DETAILED DESCRIPTION OF THE INVENTION

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

[0008] FIG. 1 is a front view illustrating a state in which a head-mounted display, i.e., a head-mounted display device 200, is worn. The head-mounted display device (hereinafter also referred to as HMD) 200 allows an observer or wearer US wearing it 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 direction or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a first virtual image display device 100A for the 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 includes a first display driver 102a disposed at the top and a first display optical system 103a covering the user's eyes. The second virtual image display device 100B includes a second display driver 102b disposed at the top and a second display optical system 103b covering the user's eyes. The HMD 200, which combines the first virtual image display device 100A and the second virtual image display device 100B, is also a virtual image display device in a broad sense. The pair of temples 100C are mounting members or support devices 106 worn on the head of the wearer US, and support the upper ends of the pair of display optical systems 103a and 103b via display drivers 102a and 102b, which are integrated in appearance. The pair of display drivers 102a and 102b is called a driver 102.

[0010] Fig. 2 is a conceptual perspective view illustrating the structure of the first display optical system 103a of the first virtual image display device 100A. Fig. 3 is a conceptual side cross-sectional view illustrating the configuration of the first display optical system 103a. The first display optical system 103a includes a plate-like display device 40 that forms a two-dimensional image and emits corresponding image light ML, and an imaging system 50 that functions as a lens for the image light ML emitted from the display device 40 to form a virtual image.

[0011] The display 40 emits image light ML and transmits external light OL. The display 40 includes a composite display member 20 that forms and emits image light ML. The composite display member 20 is a plate-like member extending along an XY plane perpendicular to the optical axis AX, and includes, in order from the external side, an image display panel 25, a patterned polarizing element 26, and a quarter-wave plate 23. The composite display member 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 by a frame (not shown). In this embodiment, the image display panel 25 and the patterned polarizing element 26 function as a polarization separation member 41 that gives different polarization components to the image light ML and the external light OL.

[0012] The display 40 is driven and operated by a drive circuit 81 of a control device 80 incorporated in the first display drive unit 102a or the drive device 102. The composite display member 20 of the display 40 is disposed close to the eye EY with the imaging system 50 sandwiched therebetween, enabling observation of a virtual image formed by the image light ML and a see-through view 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, about 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, about 5 mm to 25 mm.

[0013] 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 a drive circuit 81 to perform a display operation.

[0014] The image display panel 25 is, for example, a transmissive organic light-emitting diode (OLED) display, but may also be a micro light-emitting diode (μLED) display made of inorganic material or another self-luminous display device having transparency. Note that instead of the image display panel 25, a configuration may be adopted in which the image light ML is projected onto a transparent screen using a projection optical system.

[0015] 4 is a rear view illustrating the image display panel 25. The image display panel 25 has, on a light-transmitting flat plate 25p, light-emitting regions 25a that generate video light ML and transmissive regions 25b that transmit external light OL. On the flat plate 25p, a plurality of light-emitting regions 25a and transmissive regions 25b are arranged in a matrix along the XY plane. Each light-emitting region 25a corresponds to a pixel PX, and sub-pixels of three colors, RGB, are arranged therein.

[0016] It is desirable to arrange 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 on the external side of the image display panel 25. This prevents 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. It is also possible to arrange a light-blocking member, instead of a polarizing plate, on the external side of the image display panel 25 at a position corresponding to the light-emitting region 25a so that the external light OL does not pass through the light-emitting region 25a of the image display panel 25.

[0017] FIG. 5 is a rear view illustrating the patterned polarizer 26. The patterned polarizer 26 has a pattern that combines two types of polarizing elements and restricts the image light ML and the external light OL to a first polarization direction and a second polarization direction, respectively. By passing through the patterned polarizer 26, the polarization direction of the image light ML differs from that of the external light OL. The patterned polarizer 26 has a light-transmitting flat plate 26p, and a plurality of first polarizing elements 26a and second polarizing elements 26b are arranged in a matrix along the XY plane on the flat plate 26p. The first polarizing element 26a is disposed at a position corresponding to the light-emitting region 25a of the image display panel 25. The second polarizing element 26b is disposed at a position corresponding to the transmission region 25b of the image display panel 25. The first polarizing element 26a restricts the image light ML to a first polarization P1 in a first polarization direction, specifically, vertical polarization or perpendicular polarization. The second polarizing element 26b limits the external light OL to second polarization P2 in a second polarization direction orthogonal to the first polarization direction, specifically, horizontal polarization. The first polarizing element 26a and the second polarizing element 26b are, for example, wire-grid polarizing elements, and have polarization characteristics according to the pattern direction of a fine metallic grid made of aluminum or the like.

[0018] In addition, the patterned polarizing element 26 may be a unit composed of a polarizer (a polarizer made of a wire grid or an absorption-type TAC film, etc.) that transmits only uniformly polarized light overall, instead of the flat plate 26p, and a patterned wave plate that is patterned to have fast axes in different directions depending on the pixels of the image display panel 25.

[0019] The quarter-wave plate 23 shown in FIG. 2 and elsewhere has a principal axis midway between the X and Y directions, converting the image light ML and the external light OL from linearly polarized light to circularly polarized light. Here, the term "circularly polarized image light ML" means that, when focusing on the vibration of the electric field component or magnetic field component of the image light ML, the vibration direction rotates at the frequency of the image light ML in a plane perpendicular to the light propagation direction, and the amplitude is constant regardless of the direction. Right-handed circularly polarized light is light in which the vibration direction of the electric field component rotates clockwise as seen by an observer standing facing the direction of travel of the light beam, and left-handed circularly polarized light is light in which the vibration direction of the electric field component rotates counterclockwise. However, in this specification, if the image light ML mainly contains right-handed circularly polarized light, even if it also contains linearly polarized light in a specific direction, then such image light ML is considered to be right-handed circularly polarized light RCP. Similarly, if the image light ML mainly contains left-handed circularly polarized light, then such image light ML is considered to be left-handed circularly polarized light LCP. In this specification, right-handed circularly polarized RCP is also referred to as right-handed circularly polarized RCP, and left-handed circularly polarized LCP is also referred to as left-handed circularly polarized LCP. The quarter-wave plate 23 may be fabricated by applying a photo-crosslinkable polymer liquid crystal material to a transparent resin substrate to form a thin film and fixing the orientation state, or may be fabricated by processing a birefringent crystal material such as quartz into a thin plate.

[0020] The imaging system 50 is disposed on the face side, i.e., on the -Z side, of the display 40 or the composite display member 20, and covers the area in front of the eyes. The imaging system 50 functions as a positive lens or collimator having positive power for the image light ML.

[0021] The imaging system 50 includes a polarization selective lens 50a. The polarization selective lens 50a is an optical element whose function varies depending on the polarization. The polarization selective lens 50a has a refractive power that selectively acts on the polarization of the image light ML. In other words, the polarization selective lens 50a functions as a lens for the image light ML emitted from the display 40. In other words, the polarization selective lens 50a comprehensively forms an image of the multiple pixels that make up the image display panel 25, making it possible to observe the image formed on the image display panel 25 as a virtual image. On the other hand, the polarization selective lens 50a functions as a parallel plate for the external light OL that passes through the display 40. In other words, the external light OL is observed as a direct-view image by passing through the display 40 in a straight line.

[0022] The polarization selective lens 50a comprises, in this order from the outside world or display device 40 side, a polarizing diffractive lens 51 and an auxiliary lens 52. The polarizing diffractive lens 51 is a plate-shaped member extending along the XY plane. The auxiliary lens 52 is a lens with refractive power equivalent to that of the polarizing diffractive lens 51. Here, "equivalent" means that the absolute values ​​of the refractive power of the auxiliary lens 52 and the refractive power of the polarizing diffractive lens 51 are the same or approximately the same. The polarizing diffractive lens 51 and the auxiliary lens 52 are arranged in close proximity and parallel to each other.

[0023] The polarized diffractive lens 51 functions alone as a positive lens when a predetermined circularly polarized light is incident. The polarized diffractive lens 51 functions alone as a negative lens when a circularly polarized light opposite to the predetermined circularly polarized light is incident. The polarized diffractive lens 51 includes a liquid crystal layer in which the rotation angle of the alignment axis of the liquid crystal molecules increases with increasing distance from the optical axis AX, and this pattern is repeated periodically, so that an initial geometric phase is formed. The direction of increase in the rotation angle of the alignment axis of the liquid crystal molecules in the polarized diffractive lens 51 is polarization-dependent. The polarized diffractive lens 51 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. As described above, the auxiliary lens 52 has a refractive power equivalent to that of the polarized diffractive lens 51, i.e., a positive refractive power. The auxiliary lens 52, combined with the polarized diffractive lens 51, whose refractive power varies positively and negatively depending on the polarization, supplements 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 the image light ML, and cancels out the powers of the polarizing diffractive lens 51 and the auxiliary lens 52 for the external light OL, thereby functioning like a parallel plate glass.

[0024] The focal length of polarized diffractive lens 51 is ±f. The focal length of auxiliary lens 52 is +f. By combining polarized diffractive lens 51 and auxiliary lens 52, it is possible to realize a lens that acts as a lens with a short focal length for light of one polarization direction, while transmitting light of the other polarization direction.

[0025] In this embodiment, the auxiliary lens 52 is a refractive lens 52a. The refractive lens 52a is, for example, a convex lens, a Fresnel lens, or the like.

[0026] FIG. 6 is a diagram illustrating the function of polarized diffractive lens 51. In FIG. 6, the first region AR1 shows a first operational example of the first-type polarized diffractive lens GP1, and the second region AR2 shows a second operational example of the first-type polarized diffractive lens GP1. In FIG. 6, the third region AR3 shows a first operational example of the second-type polarized diffractive lens GP2, and the fourth region AR4 shows a second operational example of the second-type polarized diffractive lens GP2. The polarized diffractive lens 51 shown in FIG. 2 etc. is the second-type polarized diffractive lens GP2.

[0027] When right-handed circularly polarized RCP (second circularly polarized light) such as the ray L1 shown by the solid line is incident from the left side of the drawing, the polarized diffractive lens GP1 converts the right-handed circularly polarized RCP into left-handed circularly polarized LCP (first circularly polarized light) and converges it to focus at the focal point FP. When collimated left-handed circularly polarized LCP (second circularly polarized light) such as the ray L1 shown by the solid line is incident from the left side of the drawing, the polarized diffractive lens GP1 converts the left-handed circularly polarized LCP into right-handed circularly polarized RCP and diverges it. When right-handed circularly polarized RCP (diverging from the focal point FP') such as the ray L2 shown by the dashed-dot line is incident on the polarized diffractive lens GP1, the polarized diffractive lens GP1 converts the right-handed circularly polarized RCP into left-handed circularly polarized LCP and collimates it. In other words, the polarized diffractive lens GP1 functions like a positive lens with a predetermined focal length for right-handed circularly polarized RCP, reversing the direction of polarization rotation. The polarized diffractive lens GP1 also functions like a negative lens with the same absolute focal length for left-handed circularly polarized LCP, reversing the direction of polarization rotation. In other words, the polarized diffractive lens GP1 is an optical element that has a positive power for right-handed circularly polarized light RCP and a negative power for left-handed circularly polarized light LCP.

[0028] When right-handed circularly polarized light RCP, which is a collimated second circularly polarized light, such as the light ray L1 shown by the solid line from the left side of the drawing, is incident on the polarized diffractive lens GP2, it converts the right-handed circularly polarized light RCP into left-handed circularly polarized light LCP, which is a first circularly polarized light, and diverges the light. When collimated left-handed circularly polarized light LCP, such as the light ray L1 shown by the solid line from the left side of the drawing, the polarized diffractive lens GP2 converts the left-handed circularly polarized light LCP into right-handed circularly polarized light RCP and converges the light to focus at the focal point FP. In other words, the polarized diffractive lens GP2 functions like a positive lens with a predetermined focal length for left-handed circularly polarized light LCP, reversing the direction of polarization rotation. Furthermore, the polarized diffractive lens GP2 functions like a negative lens with the same absolute focal length for right-handed circularly polarized light RCP, reversing the direction of polarization rotation. In other words, the polarized diffractive lens GP2 is an optical element that has negative power for right-handed circularly polarized light RCP and positive power for left-handed circularly polarized light LCP.

[0029] The polarized diffractive lenses GP1 and GP2 have a refractive index anisotropy distribution, which is grasped in a plane by a number of annular zones centered on the optical axis AX, and function as a diffractive lens according to the refractive index anisotropy distribution and the polarization state of the incident light. Specifically, when the polarized diffractive lenses GP1 and GP2 have a refractive index anisotropy distribution in which 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 perpendicular to the central optical axis AX and perpendicular to each other, a geometric phase is formed in the specific circularly polarized light incident thereon, and the circularly polarized light is diffracted at a diffraction angle that reflects the periodic length of the rotation of the optical axis in each direction, and the polarization state is reversed. As a whole, the polarized diffractive lens causes diffraction corresponding to the power formed by the lens shape for specific circularly polarized light, 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.

[0030] Although not shown, the polarized diffractive lenses GP1 and GP2 are each formed by forming a thin liquid crystal-containing material layer on a transparent substrate, and are generally thin and plate-like. The liquid crystal-containing material layer contains a specific 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, so that an initial geometric phase is formed. The orientation axes gradually rotate within the XY plane as they move away from the optical axis AX, 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 is repeated 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. Note that the direction of increasing the rotation angle of the orientation axes of the liquid crystal molecules is reversed between the polarized diffractive lenses GP1 and GP2. The polarized diffractive lenses GP1 and GP2 can be manufactured, for example, by coating a substrate with a liquid crystal-containing material film, which is a mixture of a liquid crystal material and a UV-curable organic material layer, and then two-dimensionally scanning the liquid crystal-containing material film with UV laser light of a specific polarization state to adjust the alignment axis of the liquid crystal molecules and cure the organic material layer. This allows the alignment axis of the liquid crystal molecules in the liquid crystal-containing material layer to be controlled and fixed three-dimensionally, 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 polarized diffractive lenses GP1 themselves are known technology, such as polarization-dependent liquid crystal Fresnel lenses (see, for example, Kohei Noda, et al., Applied Optics, February 10, 2017, Vol. 56, No. 5: 1302).

[0031] The polarized diffractive lenses GP1 and GP2 can also be produced by the method for producing a liquid crystal optical element described in JP-A-2008-501147.

[0032] The polarized diffraction lens GP1 and the polarized diffraction lens GP2 do not need to be separate entities; simply rotating the polarized diffraction lens GP1 180° around the Y axis and flipping it over will result in the polarized diffraction lens GP2. In other words, by swapping the polarized diffraction lenses GP1 and GP2, they can function as both positive and negative lenses for the same circularly polarized light. This is because, in the polarized diffraction lenses GP1 and GP2, the alignment axes of the liquid crystal molecules are increased so that they rotate in a specific direction depending on the distance from the optical axis AX, as described above. Therefore, the rotation directions relative to the absolute values ​​of the distances in the ±X directions perpendicular to the optical axis AX, for example, are the same. When each of the polarized diffraction lenses GP1 and GP2 is viewed from the back, the rotation directions of the alignment axes are reversed.

[0033] The focal lengths of the polarized diffractive lenses GP1 and GP2 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 with increasing distance from the optical axis AX, the absolute value of the positive or negative power of the polarized diffractive lenses GP1 and GP2 can be increased by increasing the rate of increase in the rotation angle relative to the distance or radius from the optical axis AX, i.e., by reducing the rotation period of the alignment axis. When passing through the polarized diffractive lenses GP1 and GP2, the loss of circularly polarized light L1 is close to zero, and the polarized diffractive lenses GP1 and GP2 exhibit almost 100% transmittance.

[0034] When linearly polarized light is incident on the polarized diffractive lens GP1, the right-handed circularly polarized RCP and left-handed circularly polarized LCP components contained in the linearly polarized light behave differently. The right-handed circularly polarized RCP component is focused after passing through the polarized diffractive lens GP1, while the left-handed circularly polarized LCP component is diverged after passing through the polarized diffractive lens GP1, and the rotation direction of each polarization is reversed.

[0035] 6, and when the image light ML incident from the display 40 is left-handed circularly polarized light LCP, it functions as an optical element with positive power for the image light ML, reducing the divergence of the image light ML while reversing the direction of polarization rotation to convert it to right-handed circularly polarized light RCP. The image light ML that has passed through the polarized diffraction lens 51 enters the auxiliary lens 52 in the state of right-handed circularly polarized light RCP.

[0036] When the external light OL is right-handed circularly polarized light RCP, the polarized diffractive lens 51 functions as an optical element with negative power with respect to the external light OL, reducing the convergence of the external light OL while reversing the direction of polarization rotation to convert it to left-handed circularly polarized light LCP. The external light OL that has passed through the polarized diffractive lens 51 enters the auxiliary lens 52 in the state of left-handed circularly polarized light LCP.

[0037] The auxiliary lens 52 functions as an optical element with positive power for the image light ML, reducing the divergence while maintaining the direction of polarization rotation as right-handed circularly polarized light RCP. The absolute values ​​of the power of the polarizing diffractive lens 51 and the auxiliary lens 52 are set to be equal, and the composite focal length of the two lenses 51 and 52, i.e., the polarization selective lens 50a, is approximately equivalent to the composite focal length of two adjacent convex lenses. When the composite 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 display 40, the imaging system 50 functions as a collimator, collimating the image light ML and focusing it at the pupil position PP.

[0038] The auxiliary lens 52 functions as an optical element with positive power with respect to the external light OL, reducing the divergence while maintaining the direction of polarization rotation as left-handed circularly polarized light LCP. In this case, the two lenses 51 and 52 are positioned close to each other and are set so that the absolute values ​​of their powers are equal, and the composite focal length of the two lenses 51 and 52, i.e., the polarization selective lens 50a, is infinity. When the composite focal length of the polarization selective lens 50a is infinity, the imaging system 50 functions as an optical system equivalent to a parallel plate with nearly zero power, allowing the external light OL to travel in a nearly straight line without exerting any imaging effect such as focusing on the external light OL, thereby enabling the external light OL to be observed with the naked eye.

[0039] The second display optical system 103b is optically identical to the first display optical system 103a, or is a left-right inversion of the first display optical system 103a, and a detailed description thereof will be omitted.

[0040] In the first virtual image display device 100A, the optical device excluding the control device 80 is called the optical unit 100. In the second virtual image display device 100B, the optical device excluding the control device 80 is called the optical unit 100.

[0041] 7 is a diagram illustrating the state of light in the first display optical system 103a. In Fig. 7, a first region BR1 shows the state of the video light ML, and a second region BR2 shows the state of the external light OL.

[0042] During image observation, image light ML is emitted from the light-emitting region 25a of the image display panel 25. The image light ML emitted from the image display panel 25 includes a first polarized light P1, which is vertically polarized light, and a second polarized light P2, which is horizontally polarized light. The image light ML emitted from the image display panel 25 is incident on the patterned polarizer 26. The image light ML passes through the first polarizer 26a of the patterned polarizer 26 and is limited to the first polarized light P1. The image light ML that has passed through the patterned polarizer 26 passes through the quarter-wave plate 23 and is converted from the first polarized light P1 to left-handed circularly polarized light LCP. The imaging system 50 has positive power with respect to the left-handed circularly polarized light LCP image light ML, making it possible to observe the image light ML.

[0043] On the other hand, during observation using external light, external light OL passes through the transmission region 25b of the image display panel 25 and enters the patterned polarizer 26. The external light OL passes through the second polarizer 26b of 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 passes through the quarter-wave plate 23 and is converted from the second polarized light P2 to right-handed circularly polarized light RCP. The imaging system 50 has substantially zero power with respect to the external light OL that is right-handed circularly polarized RCP, making it possible to observe the external light OL.

[0044] The virtual image display device 100A or the display optical system 103a that performs the above-described display enables a see-through display in which the image light ML and the external light OL are superimposed.

[0045] In the above description, a display 40 incorporating a transmissive liquid crystal panel 22 was used, but other types of imager 2a, such as an organic EL (organic electroluminescence) display, can also be used instead of the transmissive liquid crystal panel 22. However, it is desirable that the imager 2a of the organic EL display blocks external light OL while an image is being displayed and transmits external light OL while the image display is stopped. In this case, it is desirable to place a polarizing plate on the light emission side of the organic EL display serving as the imager 2a.

[0046] In the above description, the image display panel 25 has been described as having three color sub-pixels, but if the chromatic aberration of the imaging system 50 is large, the imager 2a or the image display panel 25 can be made up of only single-color pixels.

[0047] The virtual image display device 100A, 100B or optical unit 100 of the first embodiment described above comprises a display 40 that emits image light ML, and a polarization selection lens 50a that is arranged opposite the display 40 and has a refractive power that selectively acts on the polarization of the image light ML. The polarization selection lens 50a comprises, in order from the display 40 side, a polarizing diffractive lens 51 that has a positive refractive power for circularly polarized image light ML and a negative refractive power for circularly polarized external light OL, and an auxiliary lens 52 that has a positive refractive power equivalent to that of the polarizing diffractive lens 51.

[0048] In the virtual image display devices 100A and 100B, the polarized diffractive lens 51 has a positive refractive power for the circularly polarized image light ML from the display device 40, and the auxiliary lens 52 has a positive refractive power for the circularly polarized image light ML that has passed through the polarized diffractive lens 51. Therefore, even when the display device 40 is placed in front of the eye, an image formed on the display surface of the display device 40 can be observed by the imaging system 50, which is thin and has a short focal length. In other words, the virtual image display devices 100A and 100B, including the imaging system 50, can be made thinner. Furthermore, the polarized diffractive lens 51 has a negative refractive power for circularly polarized external light OL, and the auxiliary lens 52 has a positive refractive power for circularly polarized external light OL that has passed through the polarized diffractive lens 51 so as to cancel out the power of the polarized diffractive lens 51, so that the external light OL can be observed.

[0049] Second Embodiment The virtual image display device of the second embodiment will be described below. 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0050] 8, the polarization selective lens 50a has a polarizing diffractive lens 51 and an auxiliary lens 52. The polarizing diffractive lens 51 and the auxiliary lens 52 can be arranged in a bonded state. The polarization selective lens 50a has thin plate-like lenses 51 and 52 arranged side by side, which allows the imaging system 50 to be made thinner.

[0051] In this embodiment, the auxiliary lens 52 is a diffractive lens 52b. The diffractive lens 52b is a flat, kinoform phase modulation lens that is polarization-independent. The diffractive lens 52b is, for example, a Fresnel zone plate or a liquid crystal lens.

[0052] Third Embodiment The virtual image display device of the third embodiment will be described below. 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0053] 9, 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 adjacent to the incident side of the imaging system 50. In this embodiment, the polarizing half mirror 60 functions as a polarization separation member 41.

[0054] The polarizing half mirror 60 is disposed 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 light polarized in a predetermined direction, selectively reflecting the image light ML from the image display panel 25 and transmitting the external light OL. The polarizing half mirror 60 has a polarization separation film 61 provided on one surface 60s of a light-transmitting substrate 60a. The polarization separation film 61 reflects, for example, a first polarization P1 of the image light ML and transmits, for example, a second polarization P2 of the external light OL. The polarization separation film 61 is formed of a dielectric multilayer film. The polarization separation film 61 may be any film that selectively reflects the image light ML and the like according to the polarization direction, and may be formed, for example, of a wire-grid polarizer. The polarizing half mirror 60 may have an anti-reflection film formed on the other surface 60t of the substrate 60a. The polarizing half mirror 60 may have either a flat or curved surface.

[0055] The polarizing half mirror 60 is tilted with respect to the vertical direction, which is perpendicular to the direction in which the eyes EY are aligned, or the Y direction. The tilt angle of the polarizing half mirror 60 is, for example, 45°, but it does not have to be 45°.

[0056] The imaging system 50 is a polarization selective lens 50a, and includes a polarizing diffractive lens 51 and an auxiliary lens 52. The polarizing diffractive lens GP2 shown in Fig. 6 is used as the polarizing diffractive lens 51. The auxiliary lens 52 may be a refractive lens 52a shown in Fig. 9 or a diffractive lens 52b shown in Fig. 8.

[0057] In this embodiment, no patterned polarizing element 26 is provided, so that the image display panel 25 has a plurality of light-emitting regions 25a arranged in a matrix pattern overall.

[0058] [Fourth embodiment] The virtual image display device of the fourth embodiment will be described below. Note that the virtual image display device of the fourth embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of parts common to the virtual image display device of the first embodiment will be omitted.

[0059] 10 , the display 40 includes an image display panel 25, a light-guiding member 70, and a quarter-wave plate 23. The quarter-wave plate 23 is disposed adjacent to the incident side of the imaging system 50. In this embodiment, a polarizing half mirror 75 of the light-guiding member 70, which will be described later, functions as a polarization separation member 41.

[0060] The light-guiding member 70 is a parallel-plate-shaped member overall, 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 polarizing half mirror 75 in the light-guiding member 70. Like the polarizing half mirror 60 of the third embodiment, the polarizing half mirror 75 reflects polarized light in a predetermined direction, selectively reflecting the image light ML from the image display panel 25 and transmitting the external light OL. The image light ML emitted from the light-guiding member 70 is, for example, a first polarized light P1. The external light OL emitted from the light-guiding member 70 is, for example, a second polarized light P2.

[0061] The first prism 71 has a convex surface 70a as an incident surface for the image light ML on the surface facing the image display panel 25. The first prism 71 guides the image light ML incident from the image display panel 25. The first prism 71 has an inner surface 71b and an outer surface 71c parallel to the quarter-wave plate 23 arranged on the exit side. The image light ML incident on the first prism 71 is totally reflected by the outer surface 71c and the inner surface 71b, and the first polarized light P1 is reflected by the polarizing half mirror 75 and exits from the light-guiding member 70.

[0062] The second prism 72 is disposed below the first prism 71 with a polarization separation film 73 interposed therebetween. The second prism 72 transmits external light OL. The external light OL incident on the second prism 72 is transmitted by the polarizing half mirror 75 as second polarized light P2, and is then emitted from the light-guiding member 70.

[0063] 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-guiding member 70, it is possible to suppress polarization changes caused by birefringence within the light-guiding member 70. This makes it possible to prevent the lens action of the polarized diffractive lens 51 of the imaging system 50 from changing on the screen and causing unevenness.

[0064] The imaging system 50 is a polarization selective lens 50a, and includes a polarization diffractive lens 51 and an auxiliary lens 52. The polarization diffractive lens 51 is the polarization diffractive lens GP2 shown in Fig. 6. The auxiliary lens 52 may be a refractive lens 52a shown in Fig. 10 or a diffractive lens 52b shown in Fig. 8.

[0065] In this embodiment, no patterned polarizing element 26 is provided, so that the image display panel 25 has a plurality of light-emitting regions 25a arranged in a matrix pattern overall.

[0066] Fifth Embodiment Hereinafter, a virtual image display device etc. of the fifth embodiment 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 parts common to the virtual image display device of the first embodiment will be omitted.

[0067] Fig. 11 is a conceptual perspective view illustrating the structure of the first display optical system 103a of the first virtual image display device 100A. Fig. 12 is a conceptual side cross-sectional view illustrating the structure of the display 40.

[0068] The display 40 includes a light source 10 that generates three colors of light as illumination light in a time-division manner and a composite display member 20 that forms and emits image light ML. The light source 10 is also part of the first display driver 102a shown in FIG. 1 and is disposed above and near the upper edge of the light-guiding member 21 (described later) of the composite display member 20 so as to supply illumination light from the upper edge to the light-guiding member 21. The composite display member 20 of the display 40 is disposed close to the eye EY with the imaging system 50 sandwiched therebetween, enabling observation of a virtual image formed by the image light ML and see-through viewing of the outside world. In the first display optical system 103a, the distance between the eye EY and the imaging system 50 along the optical axis AX is, for example, approximately 10 mm to 20 mm. The distance between the transmissive liquid crystal panel 22 of the display 40 and the imaging system 50 along the optical axis AX is, for example, approximately 5 mm to 25 mm.

[0069] The light source 10 includes one or more R light-emitting elements 10r that emit red light, one or more B light-emitting elements 10b that emit blue light, and one or more G light-emitting elements 10g that emit green light. The R light-emitting elements 10r, B light-emitting elements 10b, and G light-emitting elements 10g are self-emitting elements, such as organic light-emitting diodes (OLEDs), but may also be light-emitting diodes such as micro light-emitting diodes (μLEDs) made of inorganic materials. A multiplexer / demultiplexer including a beam splitter can be incorporated between the light source 10 and the light-guiding member 21 of the composite display member 20 to help diffuse the illumination light.

[0070] The composite display member 20 is a plate-like member extending along the XY plane perpendicular to the optical axis AX, and includes, in order from the outside, a light-guiding member 21, a transmissive liquid crystal panel 22, and a quarter-wave plate 23. The composite display member 20 has a structure in which the light-guiding member 21, the transmissive liquid crystal panel 22, and the quarter-wave plate 23 are laminated together and integrated by a frame (not shown). The light-guiding member 21 and the transmissive liquid crystal panel 22 are disposed adjacent to each other with a predetermined distance or less between them. The transmissive liquid crystal panel 22 is an imager 2a that forms image light ML. The transmissive liquid crystal panel 22 includes a plurality of pixels PX (see FIG. 12) arranged in a matrix along the XY plane.

[0071] A polarizing plate 27 (see FIG. 12) that limits polarization of the outside light OL is provided on the outside side of the light guide member 21.

[0072] The light source 10 and the light-guiding member 21 function as a backlight LL. In this embodiment, the backlight LL and the transmissive liquid crystal panel 22 (including a patterned polarizer 26, which will be described later) function as a polarization separation member 41 that gives different polarization components to the image light ML and the external light OL.

[0073] The imaging system 50 is disposed on the face side, i.e., the -Z side, of the display 40 or the composite display member 20, and covers the front of the eyes. The imaging system 50 includes a polarization selective lens 50a. The polarization selective lens 50a includes, in this order from the outside world or display 40 side, a polarizing diffractive lens 51 and an auxiliary lens 52.

[0074] Referring to Figure 12, the light source 10 generates three colors of illumination light ILr, ILg, and ILb from light-emitting elements 10r, 10g, and 10b as illumination light IL, and supplies the three colors of illumination light ILr, ILg, and ILb to the light-guiding member 21 of the composite display member 20.

[0075] The light-guiding member 21 is a light-guiding plate 11 to which a ferroelectric liquid crystal plate 12 is fixed. Illumination light ILr, ILg, ILb from the light source 10 is coupled into the light-guiding plate 11 from the upper end of the light-guiding plate 11. The light-guiding plate 11 propagates the illumination light ILr, ILg, ILb incident from the light source 10 downward.

[0076] The ferroelectric liquid crystal panel 12 is a device that performs switching operations in response to a drive signal from a drive circuit 81. It can be switched between a scattering state (ON state) that allows illumination light IL (ILr, ILg, ILb) to exit the light guide plate 11 and a transparent state (OFF state) that transmits external light OL and allows it to pass through. 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 that 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 / OFF not in units of pixels PX but across the entire surface. The ferroelectric liquid crystal layer 12a may be in a transmissive state when an electric field is applied and in a scattering state when an electric field is not applied.

[0077] Instead of the ferroelectric liquid crystal plate 12, the light guide plate 11 may be provided with a scattering member that scatters the image light ML.

[0078] The transmissive liquid crystal panel 22 includes a liquid crystal modulation element 14 and a pair of polarizing plates 15 and 16 sandwiching the liquid crystal modulation element 14. In this case, the transmissive liquid crystal panel 22 is a modulation element made of, for example, an IPS (in-plane switching) type liquid crystal, and includes image light generating pixels PX(C) and ambient light transmitting pixels PX(T). The image light generating pixels PX(C) and ambient light transmitting pixels PX(T) are arranged alternately. The liquid crystal modulation element 14 does not rotate the polarization direction of incident light when no electric field is applied, but rotates the polarization direction of 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 is similar to the patterned polarizing element 26 shown in FIG. 5.

[0079] The transmissive liquid crystal panel 22 can switch on and off for each pixel PX in response to a drive signal from the drive circuit 81, and can partially transmit incident light at any intermediate gradation between on and off. For this reason, the liquid crystal modulation member 14 includes not only the liquid crystal layer 31, the common electrode 32, the pixel electrodes 33, and the black matrix 35, but also scanning lines, signal lines, switch elements, etc., which are not shown.

[0080] In addition, the transmissive liquid crystal panel 22 or the liquid crystal modulation member 14 may be configured to rotate the polarization direction of incident light when no electric field is applied, but not rotate the polarization direction of incident light when an electric field is applied.

[0081] Fig. 13 is a diagram illustrating the state of light in the display 40. In Fig. 13, a first region CR1 indicates a case where the first display optical system 103a is in an image observation period and the display 40 is in a display state. A second region CR2 indicates a case where the first display optical system 103a is in an ambient light observation period and the display 40 is in a non-display state.

[0082] When the display 40 is in the display state during the image observation period, the light-emitting elements 10r, 10g, and 10b of the light source 10 emit light, and illumination light ILr, ILg, and ILb are supplied to the light-guiding member 21. At this timing, when the ferroelectric liquid crystal plate 12 is switched to the first state (ON state) and enters the scattering state, the illumination light ILr, ILg, and ILb pass through the first polarizer 15 of the transmissive liquid crystal panel 22 and illuminate the liquid crystal modulation member 14 as second polarized light P2, which is horizontally polarized light. 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 modulation member 14 are illumination light ILr, ILg, and ILb whose polarization planes are rotated in response to the drive signal, and only the first polarized light P1, which is vertically polarized light, is emitted via the second polarizer 16. The image light ML(R), ML(G), and ML(B) emitted from the image light generating pixel PX(C) of the transmissive liquid crystal panel 22 passes through the quarter-wave plate 23 and is converted from the first polarized light P1 to left-handed circularly polarized light LCP.

[0083] On the other hand, when the display 40 is in a non-display state during the ambient light observation period, the light source 10 is set to a non-emitting state, i.e., an extinguished state, and the supply of the illumination light IL to the light-guiding member 21 is stopped. At this timing, when the ferroelectric liquid crystal plate 12 is switched to the second state, i.e., the off state, and becomes a transmissive state, the ambient light OL travels straight across the light-guiding member 21 and enters the transmissive liquid crystal panel 22. At this time, the ambient light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 operate, for example, in a normally-off mode and are set to a maximum transmittance state by a drive signal. The second polarized light P2 of the ambient light OL that has entered the ambient light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 travels straight through the transmissive liquid crystal panel 22, i.e., the ambient light-transmitting pixels PX(T), and is then emitted. The ambient light OL that has exited the ambient light-transmitting pixels PX(T) of the transmissive liquid crystal panel 22 passes through the quarter-wave plate 23 and is converted from the second polarized light P2 to right-handed circularly polarized light RCP.

[0084] During the image observation period, the imaging system 50 has a positive power, making it possible to observe the image light ML, and during the external light observation period, the imaging system 50 has a power of approximately zero, making it possible to observe the external light OL.

[0085] 14 is a timing chart illustrating the display operation of the display optical system 103a. The horizontal axis represents time, and from top to bottom, the chart shows a blinking signal SS1 for the R light-emitting element 10r, an R drive signal SM1 for red display that is supplied to the liquid crystal modulation member 14, a blinking signal SS2 for the G light-emitting element 10g, a G drive signal SM2 for green display that is supplied to the liquid crystal modulation member 14, a blinking signal SS3 for the B light-emitting element 10b, a B drive signal SM3 for blue display that is supplied to the liquid crystal modulation member 14, and an on / off signal SD for the ferroelectric liquid crystal plate (FLC) 12. The operation of the first virtual image display device 100A includes, in each frame, a first sub-frame Z1 that is a sub-frame for video observation and a second sub-frame Z2 that is a sub-frame for ambient light observation.

[0086] 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, three colors of image light ML(R), ML(G), and ML(B) are displayed in a time-division manner, and 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 is transmitted through the external light-transmitting pixel PX(T) of the transmissive liquid crystal panel 22.

[0087] Sixth Embodiment The virtual image display device of the sixth embodiment will be described below. Note that the virtual image display device of the sixth embodiment is a partial modification of the virtual image display devices of the first and fifth embodiments, and a description of parts common to the virtual image display devices of the first embodiment, etc. will be omitted.

[0088] Fig. 15 is a conceptual side cross-sectional view illustrating the structure and light state of the first display optical system 103a. In Fig. 15, a first region DR1 indicates a case where the first display optical system 103a is in an image observation period and the display 40 is in a display state. A second region DR2 indicates a case where the first display optical system 103a is in an ambient light observation period and the display 40 is in a non-display state.

[0089] The display 40 includes a light source 10 that generates three colors of light as illumination light in a time-division manner, and a composite display member 20 that forms and emits image light ML.

[0090] The composite display member 20 comprises, in order from the outside, a light-guiding member 21, a transmissive liquid crystal panel 22, and a quarter-wave plate 23. The composite display member 20 also comprises a time-division half-wave plate 28 in which the transmissive liquid crystal panel 22 is sandwiched between a pair of liquid crystal wave plates 28a and 28b. The transmissive liquid crystal panel 22 is an imager 2a that forms image light ML. The second polarizing plate 16 on the exit side that constitutes the transmissive liquid crystal panel 22 of this embodiment is not the patterned polarizing element 26 shown in FIG. 5, but rather limits the light that passes through to a specific polarization, for example, the first polarization P1.

[0091] In this embodiment, the pixels PX of the transmissive liquid crystal panel 22 are not limited to being configured in units of each color, but may be configured with sub-pixels of three colors, RGB, and a sub-pixel for transmitting external light OL. In this case, a color filter is provided for the sub-pixel for video light ML.

[0092] A polarizing plate 27 that limits the polarization of the outside light OL is provided on the outside side of the light guide member 21.

[0093] The light source 10 and the light-guiding 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 gives different polarization components to the image light ML and the external light OL.

[0094] The backlight LL may be a laser light source or the like.

[0095] The time-division half-wave plate 28 is a device that performs a switching operation in response to a drive signal from the drive circuit 81 shown in FIG. 1. The time-division half-wave plate 28 switches the polarization direction of incident light between a first polarization direction and a second polarization direction that intersect with each other depending on the orientation direction of the liquid crystal, and passes the light. The time-division half-wave plate 28 includes 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 entirely, rather than on a pixel-by-pixel basis. When the time-division half-wave plate 28 is in the first off state, the time-division half-wave plate 28 functions as a transparent flat plate as a whole, transmitting the image light ML while maintaining its polarization direction. On the other hand, when the time-division half-wave plate 28 is in the second on state, the time-division half-wave plate 28 functions as a half-wave plate with a major axis midway between the X and Y directions as a whole, and rotating the polarization direction of the external light OL by 90°.

[0096] The first liquid crystal wave plate 28a and the second liquid crystal wave plate 28b constituting the time-division half-wave plate 28 include a liquid crystal layer sandwiched between a pair of substrates with a transparent electrode layer interposed therebetween. The liquid crystal layer is, for example, an in-plane switching (IPS) type liquid crystal, and when an electric field is applied, the first and second liquid crystal wave plates 28a and 28b function as optical elements equivalent to half-wave plates with their major or fast axes set in a specific direction (for example, midway between the X and Y directions), and when no electric field is applied, the first and second liquid crystal wave plates 28a and 28b function as isotropic parallel plates.

[0097] During the image observation period, that is, at the timing when image light ML is incident, the time-division half-wave plate 28 is in a first state, that is, an off state, and the time-division half-wave plate 28 maintains the original polarization state. During the ambient light observation period, that is, at the timing when ambient light OL is incident, the time-division half-wave plate 28 is in a second state, that is, an on state, and the time-division half-wave plate 28 switches the polarization state.

[0098] 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, and illumination light ILr, ILg, and ILb are supplied to the light-guiding member 21. At this timing, when the ferroelectric liquid crystal plate 12 is switched to the ON state and enters the scattering state, the illumination light ILr, ILg, and ILb pass through the first liquid crystal wave plate 28a of the time-division half-wave plate 28, which is in the OFF state, in its original polarization state. Thereafter, 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 modulation member 14 as second polarized light P2, which is horizontally polarized or horizontally polarized light. The image lights ML(R), ML(G), and ML(B) that have passed through the liquid crystal modulation member 14 are the illumination lights ILr, ILg, and ILb whose polarization planes have been rotated in accordance with the drive signal, and only the first polarized light P1, which is vertically polarized or perpendicularly polarized light, is emitted through the second polarizer 16 and the second liquid crystal wave plate 28b of the time-division half-wave plate 28. The image lights ML(R), ML(G), and ML(B) that have been emitted from the pixels of the transmissive liquid crystal panel 22 are converted from the first polarized light P1 to left-handed circularly polarized light LCP through the quarter-wave plate 23.

[0099] On the other hand, when the display 40 is in a non-display state during the ambient light observation period, the light source 10 is set to a non-emitting state, i.e., an extinguished state, and the supply of the illumination light IL to the light-guiding member 21 is stopped. At this timing, the ferroelectric liquid crystal plate 12 is switched to the second state (off state) and becomes transmissive. The ambient light OL travels straight through the light-guiding member 21, intersecting the light, and enters the first liquid crystal wave plate 28a of the time-division half-wave plate 28. At this time, the ambient light OL is converted from the first polarization P1 to the second polarization P2 by the first liquid crystal wave plate 28a of the time-division half-wave plate 28 in the on state. The ambient light OL that has passed through the first liquid crystal wave plate 28a enters the transmissive liquid crystal panel 22. The polarization plane of the ambient light OL that has passed through the liquid crystal modulation member 14 is rotated, and only the first polarization P1, which is vertically polarized or perpendicularly polarized, is emitted through the second polarizer 16. Thereafter, the external light OL is converted from the first polarization P1 to the second polarization P2 by the second liquid crystal wave plate 28b of the on-state time-division half-wave plate 28. The external light OL emitted from the second liquid crystal wave plate 28b passes through the quarter-wave plate 23 and is converted from the second polarization P2 to right-handed circularly polarized light RCP.

[0100] During the image observation period, the imaging system 50 has a positive power, making it possible to observe the image light ML, and during the external light observation period, the imaging system 50 has a power of approximately zero, making it possible to observe the external light OL.

[0101] 16 is a timing chart illustrating the display operation of the display optical system 103a. The horizontal axis represents time, and from top to bottom, the diagram shows a blinking signal SS1 for the R light-emitting element 10r, an R drive signal SM1 for red display that is applied to the liquid crystal modulation element 14, a blinking signal SS2 for the G light-emitting element 10g, a G drive signal SM2 for green display that is applied to the liquid crystal modulation element 14, a blinking signal SS3 for the B light-emitting element 10b, a B drive signal SM3 for blue display that is applied to the liquid crystal modulation element 14, an on / off signal SD for the ferroelectric liquid crystal plate (FLC) 12, and an on / off signal SW for the time-division half-wave plate (1 / 2λ) 28. In the operation of the first virtual image display device 100A, each frame includes a first subframe Z1, which is a subframe for video observation, and a second subframe Z2, which is a subframe for ambient light observation.

[0102] 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, three colors of image light ML(R), ML(G), and ML(B) are displayed in a time-division manner, and 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, making it possible to observe the external image.

[0103] [Variations and Others] The present invention has been described above in accordance with the embodiments, but the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0104] The display device 40 and the composite display member 20 incorporated therein are not limited to those exemplified in FIG. 3 and the like, and various types of display panels can be used.

[0105] In the imaging system 50, the polarizing diffractive lens 51 may be the polarizing diffractive lens GP1 shown in FIG. 6. In this case, the display 40 is configured so that the image light ML and the external light OL incident on the quarter-wave plate 23 are the second polarization P2 and the first polarization P1, respectively. When the image light ML incident from the display 40 is right-handed circularly polarized light RCP, the polarizing diffractive lens GP1 functions as an optical element having positive power with respect to the image light ML, reducing the divergence of the image light ML and reversing the direction of polarization rotation to convert it to left-handed circularly polarized light LCP. When the external light OL is left-handed circularly polarized light LCP, the polarizing diffractive lens GP1 functions as an optical element having negative power with respect to the external light OL, reducing the convergence of the external light OL and reversing the direction of polarization rotation to convert it to right-handed circularly polarized light RCP.

[0106] In the above description, it is assumed that the HMD 200 is used by being worn on the head, but the virtual image display devices 100A and 100B can also be used as handheld displays that are not worn on the head but are peered into like binoculars. In other words, in the present invention, the head-mounted display also includes a handheld display.

[0107] In a specific embodiment, the virtual image display device comprises a display that emits image light, and a polarization selection lens that is arranged opposite the display and has a refractive power that selectively acts on the polarization of the image light.The polarization selection lens comprises, in order from the display side, a polarized diffractive lens that has a positive refractive power for circularly polarized image light and a negative refractive power for circularly polarized external light, and an auxiliary lens that has a positive refractive power equivalent to that of the polarized diffractive lens.

[0108] In the virtual image display device, the polarized diffractive lens has a positive refractive power for circularly polarized image light from the display device, and the auxiliary lens has a positive refractive power for circularly polarized image light that has passed through the polarized diffractive lens. Therefore, even if the display device is placed in front of the eye, an image formed on the display surface of the display device can be observed by an imaging system that is thin and has a short focal length. In other words, the virtual image display device including the imaging system can be made thinner. Furthermore, the polarized diffractive lens has a negative refractive power for circularly polarized external light, and the auxiliary lens has a positive refractive power for circularly polarized external light that has passed through the polarized diffractive lens so as to cancel out the power of the polarized diffractive lens, allowing the external light to be observed.

[0109] In a specific embodiment of the virtual image display device, the display device includes a polarization separation member that is disposed on the display device side of the polarization selection lens and that causes image light and external light to have different polarization components, and a quarter-wave plate that converts predetermined linearly polarized light into predetermined circularly polarized light. In this case, the image light emitted from the display device can be circularly polarized.

[0110] In a specific embodiment of the virtual image display device, the polarized diffractive lens has a refractive index anisotropy distribution formed in a plane, and generates a geometric phase corresponding to the lens shape for predetermined circularly polarized light.

[0111] In a specific embodiment of the virtual image display device, the auxiliary lens has a refracting effect on the image light that has passed through the polarizing diffractive lens and changed from the first circularly polarized light to the second circularly polarized light.

[0112] In a specific embodiment of the virtual image display device, the polarized diffractive lens converts image light, which is left-handed circularly polarized light, into second circularly polarized light, which is right-handed circularly polarized light, and converts external light, which is right-handed circularly polarized light, into first circularly polarized light, which is left-handed circularly polarized light. In this case, the polarized diffractive lens converts the left-handed circularly polarized light of the incident image light into right-handed circularly polarized light and emits it in a relatively convergent state. In addition, the polarized diffractive lens converts the right-handed circularly polarized light of the incident external light into left-handed circularly polarized light and emits it in a relatively divergent state.

[0113] In a specific embodiment of the virtual image display device, the auxiliary lens is either a refractive lens or a diffractive lens.

[0114] In a specific embodiment of the virtual image display device, the refractive lens is either a convex lens or a Fresnel lens.

[0115] In a specific embodiment of the virtual image display device, the diffractive lens is either a Fresnel zone plate or a liquid crystal lens, in which case the polarization selection lens can be made thinner.

[0116] In a specific embodiment of the virtual image display device, the polarization separation member is a polarized half mirror that reflects a first polarization of the image light in a specific direction toward a polarization selection lens and transmits a second polarization of the external light that is perpendicular to the first polarization.

[0117] In a specific embodiment of the virtual image display device, the polarization separation member is an image display panel having a light-emitting region that forms image light and a transmissive region that transmits external light, and a patterned polarization element that is arranged between the image display panel and the polarization selection lens and that gives different polarization components to the light-emitting region and the transmissive region.

[0118] In a specific embodiment of the virtual image display device, the polarization separation member is a backlight, a liquid crystal panel having image light generating pixels and external light transmitting pixels, and a patterned polarization element that gives the image light generating pixels and the external light transmitting pixels different polarization components.

[0119] In a specific embodiment of a virtual image display device, the polarization separation member comprises a backlight, a liquid crystal panel, 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 exit side of the liquid crystal panel, and when image light is emitted by the backlight and the first liquid crystal wave plate and the second liquid crystal wave plate are in a first state, the polarization separation member emits a first polarized light in a specific direction, and when external light is emitted by turning off the backlight and the first liquid crystal wave plate and the second liquid crystal wave plate are in a second state, the polarization separation member emits a second polarized light that is perpendicular to the first polarized light.

[0120] In a specific embodiment, the optical unit comprises a display that emits image light, and a polarization selection lens that is arranged opposite the display and has a refractive power that selectively acts on the polarization of the image light.The polarization selection lens comprises, in order from the display side, a polarized diffractive lens that has a positive refractive power for circularly polarized image light and a negative refractive power for circularly polarized external light, and an auxiliary lens that has a positive refractive power equivalent to that of the polarized diffractive lens. [Explanation of symbols]

[0121] 23...quarter-wave plate, 2a...imager, 10...light source, 11...light guide plate, 12...ferroelectric liquid crystal plate, 14...liquid crystal modulation member, 15, 16...first polarizing plate, 20...composite display member, 21...light guide member, 22...transmissive liquid crystal panel, 25...image display panel, 25a...light-emitting region, 25b...transmissive region, 26...patterned polarizing element, 26a...first polarizing element, 26b...second polarizing element, 27...polarizing plate, 28...time-division half-wave plate, 28a, 28b...liquid crystal wave plates, 31...liquid crystal layer, 40...display, 50...imaging system, 50a...polarization selection lens, 51...polarized diffractive lens, 52...auxiliary lens, 52a...reflection Folded lens, 52b...diffractive lens, 60, 75...polarized 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 diffractive lens, IL...illumination light, LCP...left circularly polarized light, RCP...right circularly polarized light, LL...backlight, ML...image light, OL...external light, PP...pupil position, PX...pixel, PX(C)...image light generating pixel, PX(T)...external light transmitting pixel, US...wearer

Claims

1. a display that emits image light; a polarization selection lens disposed opposite the display and having a refractive power that selectively acts on the polarization of the image light; Equipped with The polarization selection lens includes, in order from the display device side, a polarized diffractive lens that has a positive refractive power for the circularly polarized image light and a negative refractive power for circularly polarized external light, and an auxiliary lens that has a positive refractive power equivalent to that of the polarized diffractive lens. Virtual image display device.

2. The display device includes a polarization separation member that is disposed on the display device side of the polarization selection lens and that causes the image light and the external light to have different polarization components, and a quarter-wave plate that converts predetermined linearly polarized light into predetermined circularly polarized light. The virtual image display device according to claim 1 .

3. The polarized diffractive lens has a refractive index anisotropy distribution formed in a plane, and generates a geometric phase corresponding to the lens shape for predetermined circularly polarized light. The virtual image display device according to claim 1 .

4. the auxiliary lens has a refracting effect on the image light that has passed through the polarized diffractive lens and changed from the first circularly polarized light to the second circularly polarized light; The virtual image display device according to claim 1 .

5. the polarized diffractive lens converts the image light from the first circularly polarized light, which is left circularly polarized light, to the second circularly polarized light, which is right circularly polarized light, and converts the external light from the second circularly polarized light, which is right circularly polarized light, to the first circularly polarized light, which is left circularly polarized light. The virtual image display device according to claim 4 .

6. The auxiliary lens is either a refractive lens or a diffractive lens. The virtual image display device according to claim 1 .

7. The refractive lens is either a convex lens or a Fresnel lens. The virtual image display device according to claim 6 .

8. The diffractive lens is either a Fresnel zone plate or a liquid crystal lens. The virtual image display device according to claim 6 .

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

10. the polarization separation member is an image display panel having a light-emitting region that forms the image light and a transmission region that transmits the external light, and a patterned polarization element that is disposed between the image display panel and the polarization selection lens and causes the light-emitting region and the transmission region to have different polarization components; The virtual image display device according to claim 2 .

11. the polarization separation member is a backlight, a liquid crystal panel having image light generating pixels and external light transmitting pixels, and a pattern polarization element that gives the image light generating pixels and the external light transmitting pixels different polarization components; The virtual image display device according to claim 2 .

12. the polarization separation member is a backlight, a liquid crystal panel, and a time-division half-wave plate; the time-division half-wave plate includes a first liquid crystal wave plate disposed on an incident side of the liquid crystal panel and a second liquid crystal wave plate disposed on an exit side of the liquid crystal panel, When the image light is emitted by the backlight, the time-division half-wave plate is in a first state and emits a first polarized light in a specific direction, and when the backlight is turned off and the outside light is emitted, the time-division half-wave plate is in a second state and emits a second polarized light that is orthogonal to the first polarized light. The virtual image display device according to claim 2 .

13. a display that emits image light; a polarization selection lens disposed opposite the display and having a refractive power that selectively acts on the polarization of the image light; Equipped with The polarization selection lens includes, in order from the display device side, a polarized diffractive lens that has a positive refractive power for the circularly polarized image light and a negative refractive power for circularly polarized external light, and an auxiliary lens that has a positive refractive power equivalent to that of the polarized diffractive lens. Optical unit.

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