Patent Application
20250172808
The present application is based on, and claims priority from JP Application Serial Number 2023-201297, filed on Nov. 29, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a virtual-image display device that makes it possible to observe a virtual image, and in particular, relates to a see-through type virtual-image display device that makes it possible to visually recognize the outside-world image.
A see-through type virtual-image display device that makes it possible to visually recognize the outside world is known (WO 2016/056298). The virtual-image display device includes: a liquid crystal panel including an image display region and a transparent display region formed so as to surround the image display region; and a light-guiding plate configured to guide backlight that enters an end portion from a light source. The light-guiding plate includes a light emission region configured to emit the backlight to the image display region of the liquid crystal panel, and also includes a light transmitting region that allows the ambient light to pass through. This virtual-image display device is configured such that the ambient light reaches the observer from the light transmitting region of the light-guiding plate and the transparent display region, and in a period in which the backlight is not emitted to the image display region, the ambient light passes through the light emission region of the light-guiding plate and the image display region of the liquid crystal panel, and reaches the observer. Such a configuration makes it possible to achieve see-through display in which the image light and the ambient light are superimposed on each other.
In the device described above, processing is performed in the light emission region of the light-guiding plate such that dots are formed or a scattering material is applied, and the ambient light that passes through the image display region of the liquid crystal panel passes through the processed light emission region. Thus, see-through transmittance deteriorates at or around the center of the visual field corresponding to the image display region. In order to achieve the see-through display at or around the center of the visual field with high see-through transmittance, it is necessary to additionally provide an optical system or the like having high see-through transmittance, which leads to an increase in the size of the device.
A virtual-image display device according to one aspect of the present disclosure includes, in an order from an outside world, a light-guiding member configured to cause illumination light from a light source to propagate, a ferroelectric liquid crystal plate included in the light-guiding member and configured to turn into a scattering state with respect to the illumination light and turn into a transparent state with respect to outside light, a transmissive-type liquid crystal panel configured to turn into a displaying state and a non-display state, a switching half-wave plate configured to switch a polarization direction of incident light into a first direction and a second direction depending on an alignment direction of liquid crystal to cause the light to pass through, the first direction and the second direction intersecting each other, and a polarizing lens having refractive power that causes polarized light having the first direction to be imaged as a virtual image and configured to cause polarized light having the second direction to pass through, in which when the transmissive-type liquid crystal panel is in the displaying state, the switching half-wave plate causes image light from the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the first direction, and when the transmissive-type liquid crystal panel is in the non-display state, the switching half-wave plate causes the outside light that passes through the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the second direction.
Below, a virtual-image display device according to a first embodiment will be described with reference to
The HMD 200 includes a first virtual-image display device 100A for a right eye, a second virtual-image display device 100B for a left eye, a pair of temples 100C that support 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 driving unit 102a disposed at an upper part, a first display optical system 103a that covers the front of the eye, and a light transmitting cover 104a that covers the first display optical system 103a at the outside-world side or the front side. The second virtual-image display device 100B includes a second display driving unit 102b disposed at an upper part, a second display optical system 103b that covers the front of the eye, and a light transmitting cover 104b that covers the second display optical system 103b at the outside-world side or the front side. The HMD 200 in which the first virtual-image display device 100A and the second virtual-image display device 100B are combined together is also a virtual-image display device in a broader sense. The pair of temples 100C function as a mounting member or a supporting unit 106 that is worn on the head of the wearer US, and support the upper end sides of the pair of display optical systems 103a and 103b and the upper end sides of the pair of light transmitting covers 104a and 104b via the display driving units 102a and 102b integrated in exterior. A combination of the pair of display driving units 102a and 102b is referred to as a driving device 102. A combination of the pair of light transmitting covers 104a and 104b is referred to as a shade 104.
The light source 10 includes an R light-emitting element 10r configured to generate light of red, a B light-emitting element 10b configured to generate light of blue, and a G light-emitting element 10g configured to generate light of green. The R light-emitting element 10r, the B light-emitting element 10b, and the G light-emitting element 10g are self light-emitting elements, and may be, for example, organic light emitting diodes (OLED) or light emitting diodes such as a micro light emitting diode (μLED) made of inorganic material. The R light-emitting element 10r, the B light-emitting element 10b, and the G light-emitting element 10g are not limited to an element embedded alone. In other words, the light source 10 is a combination of one or a plurality of R light-emitting elements 10r, one or a plurality of B light-emitting elements 10b, and one or a plurality of G light-emitting elements 10g. A multiplexer/demultiplexer including a beam splitter used to facilitate diffusion of illumination light can be incorporated between the light source 10 and the light-guiding member 21 of the composite display member 20.
The composite display member 20 is a plate-shape member extending along the XY plane perpendicular to the optical axis AX, and includes the light-guiding member 21, a transmissive-type liquid crystal panel 22, and a switching half-wave plate 23, in the order from the outside world. The composite display member 20 is a plate-shape member as a whole in which the light-guiding member 21, the transmissive-type liquid crystal panel 22, and the switching half-wave plate 23 are stacked to each other, and has a structure integrated by a frame body (not illustrated). Here, the light-guiding member 21, the transmissive-type liquid crystal panel 22, and the switching half-wave plate 23 are fixed to each other in a state where they are disposed close to each other with a predetermined interval being provided between them. Note that the transmissive-type liquid crystal panel 22 includes a plurality of pixels PX (see
The polarizing lens 50 is disposed at the face side of the composite display member 20, that is, at the −Z side to cover the front of the eye. More specifically, the polarizing lens 50 is opposed to the switching half-wave plate 23 in the composite display member 20, and is disposed at an opposite side from the transmissive-type liquid crystal panel 22. The polarizing lens 50 is a plate-shaped member extending along the XY plane. The polarizing lens 50 operates differently according to the polarization direction of the incident light. The polarizing lens 50 functions as a lens for the image light ML outputted from the composite display member 20. That is, the polarizing lens 50 comprehensively causes a plurality of pixels that constitute the transmissive-type liquid crystal panel 22 to form an image. This enables the image formed on the transmissive-type liquid crystal panel 22 to be observed as a virtual image. In addition, the polarizing lens 50 functions as a parallel flat plate for the outside light OL that passed through the composite display member 20. Specifically, the polarizing lens 50 is a liquid crystal lens, and includes a plurality of circular-shaped ring zone sections RA having different refractive-index states. The group of ring zone sections RA is disposed coaxially so as to be symmetrical around the optical axis AX. In the group of the ring zone sections RA, a ring zone section RA at a periphery away from the optical axis AX has a width in the radial direction with the optical axis Ax being the center, and this width is narrower than that of a ring zone section RA at the center where the optical axis AX passes through. That is, the width of the ring zone section RA in the radial direction reduces toward the periphery.
The second display optical system 103b is optically the same as the first display optical system 103a, or is obtained by inverting the first display optical system 103a horizontally. Thus, detail description thereof will not be given.
With reference to
The light-guiding member 21 is obtained by fixing a ferroelectric liquid crystal plate 12 to the light-guiding plate 11. The illumination lights ILr, ILg, ILb from the light source 10 are combined into the light-guiding plate 11 from the upper end of the light-guiding plate 11. The light-guiding plate 11 propagates downward the illumination light ILr, ILg, ILb entering from the light source 10.
The light-guiding plate 11 includes a flat plate having optical transparency, and includes a pair of flat surfaces 11a and 11b. At the flat surface 11b on the rear side of the light-guiding plate 11, the ferroelectric liquid crystal plate 12 is bonded in a close contacting state, and is fixed to the light-guiding plate 11. The ferroelectric liquid crystal plate 12 is provided so as to be attached to the light-guiding plate 11. In other words, the ferroelectric liquid crystal plate 12 is included in the light-guiding member 21 including the light-guiding plate 11. The ferroelectric liquid crystal plate 12 is a unit configured to perform switching-type operation in accordance with a drive signal from the driving circuit 81, and is able to switch between a scattering state where the illumination light IL (ILr, ILg, ILb) is outputted to the outside of the light-guiding plate 11 and a transparent state where the outside light OL is caused to pass through and is allowed to pass through. The ferroelectric liquid crystal plate 12 includes a ferroelectric liquid crystal layer 12a interposed between a pair of base members 12b and 12c with a transparent electrode layer (not illustrated) being interposed between them. The ferroelectric liquid crystal layer 12a is, for example, a reverse-mode polymer-dispersed liquid crystal, and turns into a transmitting state when no electric field is applied whereas turning into a scattering state when an electric field is applied (see, for example, JP-A-6-308543 or the like). The ferroelectric liquid crystal plate 12 is able to switch between ON and OFF over the entire surface rather than on a pixel basis. When the ferroelectric liquid crystal plate 12 is in the OFF state, the ferroelectric liquid crystal plate 12 entirely turns into the transparent state to allow the illumination light IL to be guided within the light-guiding plate 11, and cause the outside light OL entering the ferroelectric liquid crystal plate 12 from the outside world through the light-guiding plate 11 to pass through to allow it to pass through. On the other hand, when the ferroelectric liquid crystal plate 12 is in the ON state, the ferroelectric liquid crystal plate 12 entirely turns into the scattering state to prevent the total reflection of the illumination light IL within the light-guiding plate 11, and outputs the illumination light IL to the outside of the light-guiding plate 11. In addition, the ferroelectric liquid crystal plate 12 restricts passage of the outside light OL passing through the light-guiding plate 11 from the outside world and entering the liquid crystal plate 12. Note that the ferroelectric liquid crystal layer 12a may be configured to turn into the transmitting state when an electric field is applied, and turn into the scattering state when no electric field is applied.
The transmissive-type liquid crystal panel 22 is opposed to the light-guiding plate 11 or the ferroelectric liquid crystal plate 12, and is disposed at the face side, that is, at the −Z side. The transmissive-type liquid crystal panel 22 includes a liquid-crystal modulation member 14, and a pair of polarizing plates 15 and 16 between which the liquid-crystal modulation member 14 is interposed. In this case, the transmissive-type liquid crystal panel 22 or the liquid-crystal modulation member 14 is a modulation element comprised, for example, of an in-plane switching (IPS) type liquid crystal, and operates pixel PX by pixel PX. The pixel PX does not includes a filter, and is colorless. The liquid-crystal modulation member 14 does not rotate the polarization direction of incident light when no electric field is applied, and 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 disposed in a direction intersecting the polarization direction, more specifically, in a direction in which the polarization direction is perpendicular. In other words, the image light ML or the outside light OL that has passed through the transmissive-type liquid crystal panel 22 and has been outputted from the polarizing plate 16 is first polarized light P1 of which polarization direction is vertical and is a first direction (see
Note that the transmissive-type liquid crystal panel 22 or the liquid-crystal modulation member 14 rotates the polarization direction of incident light when no electric field is applied, and does not rotate the polarization direction of incident light when an electric field is applied. In this case, the pair of polarizing plates 15 and 16 are disposed such that polarization directions are parallel to each other.
The switching half-wave plate 23 is opposed to the transmissive-type liquid crystal panel 22, and is disposed at an opposite side from the light-guiding plate 11. The switching half-wave plate 23 is a unit configured to perform switching-type operation in accordance with a drive signal from the driving circuit 81, and switches the polarization direction of incident light between the first direction and the second direction that intersect each other depending on an alignment direction of liquid crystal to cause the incident light to pass through. The switching half-wave plate 23 includes a liquid crystal layer 17a interposed between a pair of base members 17b and 17c with a transparent electrode layer (not illustrated) being interposed between them. The liquid crystal layer 17a is, for example, an in-plane switching (IPS) type liquid crystal or the like, and does not rotate the polarization direction of incident light when no electric field is applied whereas rotating the polarization direction of incident light when an electric field is applied. The switching half-wave plate 23 is able to switch between ON and OFF over the entire surface rather than on a pixel basis. When the switching half-wave plate 23 is in the OFF state, the switching half-wave plate 23 entirely functions as a transparent flat plate, and causes the image light ML (in other words, the first polarized light P1 of which polarization direction is vertical and is the first direction, that is, the ±Y direction) to pass through while its polarization direction is maintained (see a first region AR1 in
The polarizing lens 50 disposed at the face side of the switching half-wave plate 23 includes a liquid crystal layer 18a interposed between a pair of base members 18b and 18c with a transparent electrode layer (not illustrated) being interposed between them. As described above, the liquid crystal layer 18a includes a number of circular-shaped ring zone sections RA (see
Below, with reference to
In a first stage of the image observation period, of the light-emitting elements 10r, 10g, and 10b of the light source 10, the R light-emitting element 10r emits light to supply the light-guiding member 21 with illumination light ILr that is red light, for example. At this timing, when the ferroelectric liquid crystal plate 12 is switched into the ON state to turn into the scattering state, the illumination light ILr passes through the first polarizing plate 15 of the transmissive-type liquid crystal panel 22, and serves as the second polarized light P2 that is the lateral polarized light to illuminate the liquid-crystal modulation member 14. In other words, each of the colorless pixels PX that constitute the transmissive-type liquid crystal panel 22 is illuminated. The image light QL that has passed through the liquid-crystal modulation member 14 is light obtained by rotating the polarization surface of the illumination light ILr in accordance with a drive signal, and only the first polarized light P1 that has passed through the second polarizing plate 16 and is vertical polarized light is outputted as the image light ML(R). The image light ML(R) outputted from each of the pixels PX of the transmissive-type liquid crystal panel 22 enters the switching half-wave plate 23. At this time, the switching half-wave plate 23 is switched into the OFF state to function as a transparent flat plate, and causes the image light ML(R) of the first polarized light P1 to pass through while its polarization direction is maintained. The image light ML(R) of the first polarized light P1 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 functioning as a convex lens for the first polarized light P1 to form a virtual image.
In a second stage of the image observation period, while the ferroelectric liquid crystal plate 12 is maintained to be in the ON state, the G light-emitting element 10g of the light source 10 emits light instead of the R light-emitting element 10r to supply the light-guiding member 21 with the illumination light ILg that is green light, and the light is outputted toward the side direction from the light-guiding member 21. The image light QL passing through individual pixels PX that constitute the transmissive-type liquid crystal panel 22 or the liquid-crystal modulation member 14 illuminated with the illumination light ILg is light obtained by rotating the polarization surface of the illumination light ILg in accordance with a drive signal. Individual pixels PX of the transmissive-type liquid crystal panel 22 output image light ML(G) that is the first polarized light P1. The switching half-wave plate 23 is maintained to be in the OFF state. The image light ML(G) of the first polarized light P1 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 functioning as a convex lens for the first polarized light P1 to form a virtual image.
In a third stage of the image observation period, while the ferroelectric liquid crystal plate 12 is maintained to be in the ON state, the B light-emitting element 10b of the light source 10 emits light instead of the G light-emitting element 10g to supply the light-guiding member 21 with the illumination light ILb that is blue light, and the light is outputted toward the side direction from the light-guiding member 21. The image light QL passing through individual pixels PX that constitute the transmissive-type liquid crystal panel 22 or the liquid-crystal modulation member 14 illuminated with the illumination light ILb is light obtained by rotating the polarization surface of the illumination light ILb in accordance with a drive signal. Individual pixels PX of the transmissive-type liquid crystal panel 22 output image light ML(B) that is the first polarized light P1. The switching half-wave plate 23 is maintained to be in the OFF state. The image light ML(B) of the first polarized light P1 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 functioning as a convex lens for the first polarized light P1 to form a virtual image.
During the image observation period, in other words, when the transmissive-type liquid crystal panel 22 is in the displaying state, the image lights ML(R), ML(G), and ML(B) of three colors are sequentially displayed. The switching half-wave plate 23 causes the first polarized light P1 that is the image light ML from the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50. The wearer US recognizes a color image.
In addition, in an outside-light observation period, the light source 10 is turned into a non-emitting state, that is, into a turning-off state to stop supplying the illumination light IL to the light-guiding member 21. At this timing, once the ferroelectric liquid crystal plate 12 is switched into the OFF state to turn into the transmitting state, the outside light OL travels straight so as to intersect the light-guiding member 21, and enters the transmissive-type liquid crystal panel 22. At this time, individual pixels PX of the transmissive-type liquid crystal panel 22 operate, for example, in a normally-off manner, and are brought into a maximum transmitting state in accordance with a drive signal. Of the outside light OL entering the pixels PX of the transmissive-type liquid crystal panel 22, the second polarized light P2 travels straight through the transmissive-type liquid crystal panel 22, that is, through the pixels PX to be converted into the first polarized light P1, and enters the switching half-wave plate 23. At this time, the switching half-wave plate 23 is switched into the ON state to function as a half wave plate, and causes the polarization direction of the outside light OL that is the first polarized light P1 to rotate by 90° to output it as the second polarized light P2. In other words, when the transmissive-type liquid crystal panel 22 is in the non-display state, the switching half-wave plate 23 causes the outside light OL that has passed through the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50 as the second polarized light P2. The outside light OL of the second polarized light P2 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 that functions as a parallel flat plate for the second polarized light P2, and enters the eye EY without receiving any image formation operation by the composite display member 20 or the polarizing lens 50.
In a red-color display section Δ1 corresponding to the first stage of the first sub-frame Z1 for observing an image, the driving circuit 81 turns the ferroelectric liquid crystal plate 12 into the ON state, turns on the R light-emitting element 10r, outputs the R drive signal SM1 for red display to each of the pixels PX of the transmissive-type liquid crystal panel 22, and turns the switching half-wave plate 23 into the OFF state. With this operation, the red image light ML(R) enters the eye EY. In addition, with the polarizing lens 50, it is possible to observe a virtual image corresponding to a red pattern formed on the transmissive-type liquid crystal panel 22. In a green-color display section Δ2 corresponding to the second stage of the first sub-frame Z1, the driving circuit 81 maintains the ferroelectric liquid crystal plate 12 to be in the ON state, turns on the G light-emitting element 10g, outputs the G drive signal SM2 for green display to each of the pixels PX of the transmissive-type liquid crystal panel 22, and maintains the switching half-wave plate 23 to be in the OFF state. With this operation, the green image light ML(G) enters the eye EY. In addition, with the polarizing lens 50, it is possible to observe a virtual image corresponding to a green pattern formed on the transmissive-type liquid crystal panel 22. In a blue-color display section Δ3 corresponding to the third stage of the first sub-frame Z1, the driving circuit 81 maintains the ferroelectric liquid crystal plate 12 to be in the ON state, turns on the B light-emitting element 10b, outputs the B drive signal SM3 for blue display to each of the pixels PX of the transmissive-type liquid crystal panel 22, and maintains the switching half-wave plate 23 to be in the OFF state. With this operation, the blue image light ML (B) enters the eye EY. In addition, with the polarizing lens 50, it is possible to observe a virtual image corresponding to a blue pattern formed on the transmissive-type liquid crystal panel 22.
In the first sub-frame Z1, that is, the image observation period described above, the image lights ML(R), ML(G), and ML(B) of three colors are sequentially displayed by the transmissive-type liquid crystal panel 22 that is in the displaying state or the transmitting state, whereby the wearer US recognizes a color image.
In the second sub-frame Z2 for observing the outside world, the driving circuit 81 turns the ferroelectric liquid crystal plate 12 into the OFF state to cause the outside light OL to pass through, turns off the light source 10, outputs, for example, a drive signal with the maximum transmissivity to each of the pixels PX of the transmissive-type liquid crystal panel 22, and turns the switching half-wave plate 23 into the ON state. At this time, the transmissive-type liquid crystal panel 22 is in the non-display state and also in the transmitting state. With this operation, the outside light OL that travels straight through the transmissive-type liquid crystal panel 22 and the polarizing lens 50 enters the eye EY, whereby it is possible to observe the outside-world image.
The structure of the first embodiment described above is given merely as an example. For example, the transmissive-type liquid crystal panel 22 does not need to operate in a normally-off manner, and may operate in a normally-on manner. In a case of operation in a normally-on manner, the drive signals SM1, SM2, and SM3 illustrated in
The switching half-wave plate 23 may be configured to rotate the polarization direction of the image light ML by 90° to output it as the second polarized light P2, and cause the outside light OL to pass through as the first polarized light P1 while maintaining the polarization direction thereof as it is. In this case, the polarizing lens 50 has refractive power that causes the image light ML of the second polarized light P2 to be imaged as a virtual image, and serves as the parallel flat plate to cause the outside light OL of the first polarized light P1 to pass through as it is. Note that the second polarized light P2 that receives an image formation operation by such a polarizing lens 50 can be called first polarized light, and the first polarized light P1 that does not receive any image formation operation by this polarizing lens 50 can be called second polarized light.
The light-guiding member 21 is not limited to a member in which the ferroelectric liquid crystal plate 12 is fixed to the eye EY side of the light-guiding plate 11, and may be a member in which the ferroelectric liquid crystal plate 12 is fixed to the outside-world side of the light-guiding plate 11.
The first sub-frame Z1 and the second sub-frame Z2 illustrated in
In the first sub-frame Z1, the pixels PX of the transmissive-type liquid crystal panel 22 do not need to be set in the maximum transmitting state. By adjusting the transmittance of the pixels PX, it is possible to adjust the intensity of the transmissivity for the outside light OL as with photochromic sunglasses. At this time, it is possible to adjust the transmittance at local areas of the transmissive-type liquid crystal panel 22, rather than at the entire area.
The virtual-image display device 100A, 100B according to the first embodiment described above includes, in the order from the outside world: the light-guiding member 21 configured to cause the illumination light IL from the light source 10 to propagate; the ferroelectric liquid crystal plate 12 included in the light-guiding member 21 and configured to turn into the scattering state with respect to the illumination light IL and turn into the transparent state with respect to the outside light OL; the transmissive-type liquid crystal panel 22 configured to turn into the displaying state and the non-display state; the switching half-wave plate 23 configured to switch a polarization direction of incident light into the first direction and the second direction depending on the alignment direction of liquid crystal to cause the light to pass through, the first direction and the second direction intersecting each other; and the polarizing lens 50 having refractive power that causes the first polarized light P1 having the first direction to be imaged as a virtual image and configured to cause the second polarized light P2 having the second direction to pass through, in which when the transmissive-type liquid crystal panel 22 is in the displaying state, the switching half-wave plate 23 causes the image light ML from the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50 as the first polarized light P1 having the first direction, and when the transmissive-type liquid crystal panel 22 is in the non-display state, the switching half-wave plate 23 causes the outside light OL that passes through the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50 as the second polarized light P2 having the second direction.
With the virtual-image display device described above, when the transmissive-type liquid crystal panel 22 is in the displaying state, the switching half-wave plate 23 causes the image light ML from the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50 as the first polarized light P1 having the first direction, and when the transmissive-type liquid crystal panel 22 is in the non-display state, the switching half-wave plate 23 causes the outside light OL that passes through the transmissive-type liquid crystal panel 22 to enter the polarizing lens 50 as the second polarized light P2 having the second direction. This makes it possible to switch the image light ML and the outside light OL to observe it in a parallel manner. In other words, by using the ferroelectric liquid crystal plate 12, it is possible to use the transmissive-type liquid crystal panel 22 for the purpose of observing the image and observing the outside world. Thus, it is possible to suppress a reduction in the see-through transmittance while maintaining the brightness of display.
In the virtual-image display device 100A, 100B according to the first embodiment, the light source 10 switches and generates illumination light of red, illumination light of green, and illumination light of blue, the transmissive-type liquid crystal panel 22 includes a colorless pixel PX, and performs modulation with the pixel PX in accordance with the color of the illumination light generated by the light source 10, and the transmissive-type liquid crystal panel 22 turns the pixel PX into the transmitting state when the light source 10 does not emit light. In this case, during the first sub-frame Z1 that is the sub-frame for observing an image, there are display sections Δ1, Δ2, and Δ3 for individual colors in which the image lights ML(R), ML(G), and ML(B) of red, green, and blue are displayed.
Below, a virtual-image display device or the like according to a second embodiment will be described. Note that the virtual-image display device according to the second embodiment is provided by partially modifying the virtual-image display device according to the first embodiment. Thus, explanation of portions common to the virtual-image display device according to the first embodiment will not be repeated.
In the first display optical system 103a or the first virtual-image display device 100A illustrated in
In the sub-pixel PXs (R) for red display, a red color filter 41r is disposed at or around the first polarizing plate 15. In the sub-pixel PXs(G) for green display, a green color filter 41g is disposed at or around the first polarizing plate 15. In the sub-pixel PXs(B) for blue display, a blue color filter 41b is disposed at or around the first polarizing plate 15.
A state of light in the first display optical system 103a will be described with reference to
In the image observation period, by causing all the light-emitting elements 10r, 10g, and 10b that constitute the light source 10 to emit light, the white illumination light ILr, ILg, ILb is supplied to the light-guiding member 21. At this timing, when the ferroelectric liquid crystal plate 12 is switched into the ON state to turn into the scattering state, the second polarized light P2 of the illumination light ILr, ILg, ILb passes through the first polarizing plate 15 of the transmissive-type liquid crystal panel 22, and illuminates the sub-pixels PXs(R), PXs(G), and PXs(B) that constitute each of the pixels PX. Thus, the ML(R), the ML(G), and the ML(B) of the first polarized light P1 that have been modulated are outputted in parallel from the transmissive-type liquid crystal panel 22. The image light ML(R), ML(G), ML(B) outputted from each of the sub-pixels PXs(R), PXs(G), PXs(B) of the transmissive-type liquid crystal panel 22 enters the switching half-wave plate 23 that is in the OFF state. The switching half-wave plate 23 causes the image light ML(R), ML(G), ML(B) of the first polarized light P1 to pass through while its polarization direction is maintained as it is. The image light ML(R), ML(G), ML(B) of the first polarized light P1 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 functioning as a convex lens for the first polarized light P1 to form a virtual image.
On the other hand, in the outside-light observation period, by turning the light source 10 into the non-emitting state, that is, into the turning-off state, supplying of the illumination light IL to the light-guiding member 21 is stopped, and the ferroelectric liquid crystal plate 12 is switched into the OFF state to turn into the transmitting state. The outside light OL travels straight so as to intersect the light-guiding member 21, and enters the transmissive-type liquid crystal panel 22. At this time, the sub-pixels PXs(R), PXs(G), and PXs(B) that constitute each of the pixels PX of the transmissive-type liquid crystal panel 22 are, for example, in the maximum transmitting state. The second polarized light P2 of the outside light OL travels straight through the transmissive-type liquid crystal panel 22, that is, through the sub-pixels PXs(R), PXs(G), and PXs(B) to be converted into the first polarized light P1, and enters the switching half-wave plate 23. The switching half-wave plate 23 in the ON state rotates the polarization direction of the outside light OL of the first polarized light P1 by 90°, and outputs the light as the second polarized light P2. The outside light OL of the second polarized light P2 that has passed through the switching half-wave plate 23 passes through the polarizing lens 50 functioning as a parallel flat plate for the second polarized light P2, and enters the eye EY without receiving any image formation operation by the composite display member 20 and the polarizing lens 50.
operation by the first virtual-image display device 100A, and corresponds to the timing chart illustrated in
In the present embodiment, it may also possible to employ a configuration in which the switching half-wave plate 23 rotates the polarization direction of the image light ML by 90° to output the light as the second polarized light P2, and causes the outside light OL to pass through as the first polarized light P1 while its polarization direction is maintained as it is. In addition, the time width or the time ratio of the sub-frames Z1 and Z2 is adjustable, for example, by the control device 80 in accordance with the environments of the outside world.
In the second sub-frame Z2 that is the sub-frame for observing the outside light, each of the sub-pixels PXs(R), PXs(G), and PXs(B) that constitute the transmissive-type liquid crystal panel 22 does not need to be in the maximum transmitting state, and it is possible to individually adjust the transmittance of each of the sub-pixels PXs(R), PXs(G), and PXs(B).
In the virtual-image display device 100A, 100B according to the second embodiment, the light source 10 generates white illumination light ILr, ILg, ILb, and the transmissive-type liquid crystal panel 22 includes a red sub-pixel PXs(R), a green sub-pixel PXs(G), and a blue sub-pixel PXs(B) to perform modulation with the sub-pixels PXs(R), PXs(G), and PXs(B) for individual colors in accordance with the light emitted by the light source 10, and turns the sub-pixels PXs(R), PXs(G), and PXs(B) for individual colors into the transmitting state when the light source 10 does not emit light. In this case, in the first sub-frame Z1 that is the sub-frame for observing an image, it is possible to display the red image light ML, the green image light ML, and the blue image light ML at the same time.
Below, a virtual-image display device or the like according to a third embodiment will be described. Note that the virtual-image display device according to the third embodiment is provided by partially modifying the virtual-image display device according to the first embodiment. Thus, explanation of portions common to the virtual-image display device according to the first embodiment will not be repeated.
In the first display optical system 103a or the first virtual-image display device 100A illustrated in
For example, as illustrated in
In the image observation period illustrated in
On the other hand, in the outside-light observation period illustrated in
As illustrated in
In the virtual-image display device 100A, 100B according to the third embodiment, the light source 10 switches and generates illumination light ILr of red, illumination light ILg of green, and illumination light ILb of blue, and the transmissive-type liquid crystal panel 22 includes the colorless displaying pixel PX(D) and the colorless transmitting pixel PX(T) to perform modulation with the colorless displaying pixel PX(D) in accordance with the color of the illumination light ILr, ILg, ILb generated by the light source 10, and turns the colorless transmitting pixel PX(T) into the transmitting state when the light source 10 does not emit light. In this case, during the first sub-frame Z1 that is the sub-frame for observing an image, there are display sections Δ1, Δ2, and Δ3 for individual colors in which the image lights ML(R), ML(G), and ML(B) of red, green, and blue are displayed. In addition, in the second sub-frame 22 that is the sub-frame for observing the outside light, by operating at least the colorless transmitting pixel PX(T), it is possible to observe the color image and the see-through image in a time-division manner.
In the virtual-image display device 100A according to a modification example illustrated in
In the virtual-image display device 100A according to the modification example illustrated in
Below, a virtual-image display device or the like according to a fourth embodiment will be described. Note that the virtual-image display device according to the fourth embodiment is provided by partially modifying the virtual-image display device according to the second embodiment. Thus, explanation of portions common to the virtual-image display device according to the second embodiment will not be repeated.
In the first display optical system 103a or the first virtual-image display device 100A illustrated in
An array of sub-pixels PXs will be described with reference to
In the image observation period illustrated in
On the other hand, in the outside-light observation period illustrated in
As illustrated in
In the virtual-image display device 100A, 100B according to the fourth embodiment, the light source 10 generates white illumination light ILr, ILg, ILb, and the transmissive-type liquid crystal panel 22 includes the sub-pixel PXs(R) for red, the sub-pixel PXs(G) for green, the sub-pixel PXs(B) for blue, and the colorless sub-pixel PXs(T) to perform modulation with sub-pixels PXs(R), PXs(G), and PXs(B) for individual colors in accordance with the light emitted by the light source 10, and turns the colorless sub-pixel PXs(T) into the transmitting state when the light source 10 does not emit light. In this case, in the first sub-frame Z1 that is the sub-frame for observing an image, it is possible to display the red image light ML(R), the green image light ML(G), and the blue image light ML(B) at the same time. In addition, in the second sub-frame Z2 that is the sub-frame for observing the outside light, by operating at least the colorless sub-pixel PXs(T), it is possible to observe the color image and the see-through image in a time-division manner.
In the virtual-image display device 100A according to the modification example illustrated in
These are descriptions of the present disclosure with reference to the embodiments. However, the present disclosure is not limited to the embodiments described above. It is possible to implement the present disclosure in various modes without departing from the spirit of the disclosure. For example, the following modifications are possible.
The liquid crystal lens serving as the polarizing lens 50 is not limited to that including a ring zone section RA having a ring shape. For the polarizing lens 50, it may be possible to employ various types of structures having a lens function for certain polarized light.
In the description above, it is assumed that the HMD 200 is mounted on the head, and is used. However, the virtual-image display device 100A, 100B described above can be used as a hand-held display that is not worn on the head and is to be looked into like binoculars. In other words, in the present disclosure, the head-mounted display includes a hand-held display.
A virtual-image display device according to a specific aspect includes, in the order from the outside world: a light-guiding member configured to cause illumination light from a light source to propagate; a ferroelectric liquid crystal plate included in the light-guiding member and configured to turn into a scattering state with respect to the illumination light and turn into a transparent state with respect to outside light; a transmissive-type liquid crystal panel configured to turn into a displaying state and a non-display state; a switching half-wave plate configured to switch a polarization direction of incident light into a first direction and a second direction depending on an alignment direction of liquid crystal to cause the light to pass through, the first direction and the second direction intersecting each other; and a polarizing lens having refractive power that causes polarized light having the first direction to be imaged as a virtual image and configured to cause polarized light having the second direction to pass through, in which when the transmissive-type liquid crystal panel is in the displaying state, the switching half-wave plate causes image light from the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the first direction, and when the transmissive-type liquid crystal panel is in the non-display state, the switching half-wave plate causes the outside light that passes through the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the second direction.
In the virtual-image display device described above, when the transmissive-type liquid crystal panel is in the displaying state, the switching half-wave plate causes the image light from the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the first direction, and when the transmissive-type liquid crystal panel is in the non-display state, the switching half-wave plate causes the outside light that passes through the transmissive-type liquid crystal panel to enter the polarizing lens as the polarized light having the second direction. Thus, it is possible to switch the image light and the outside light and observe them in parallel. In other words, by utilizing the ferroelectric liquid crystal plate, it is possible to use the transmissive-type liquid crystal panel to observe the image as well as to observe the outside world, and it is possible to suppress a deterioration in the see-through transmittance while securing the brightness of display.
In the virtual-image display device according to the specific aspect, the light source switches and generates illumination light of red, illumination light of green, and illumination light of blue, the transmissive-type liquid crystal panel includes a colorless pixel, and performs modulation with the pixel in accordance with the color of the illumination light generated by the light source, and the transmissive-type liquid crystal panel turns the pixel into a transmitting state when the light source does not emit light. In this case, during the sub-frame for observing an image, there are display sections for individual colors in which image lights of red, green, and blue are displayed.
In the virtual-image display device according to the specific aspect, the light source switches and generates illumination light of red, illumination light of green, and illumination light of blue, the transmissive-type liquid crystal panel includes a colorless displaying pixel and a colorless transmitting pixel to perform modulation with the colorless displaying pixel in accordance with the color of the illumination light generated by the light source, and turns the colorless transmitting pixel into a transmitting state when the light source does not emit the light. In this case, during the sub-frame for observing an image, there are display sections for individual colors in which image lights of red, green, and blue are displayed. In addition, during the sub-frame for observing the outside light, by operating at least the colorless transmitting pixel, it is possible to observe the color image and the see-through image in a time-division manner.
In the virtual-image display device according to the specific aspect, an effective region of the ferroelectric liquid crystal plate is formed locally in a region that is opposed to the colorless displaying pixel of the transmissive-type liquid crystal panel. The colorless transmitting pixel does not need to scatter the outside light, and only by locally forming the effective region of the ferroelectric liquid crystal plate in a region that is opposed to the colorless displaying pixel, it is possible to cause the illumination light to selectively enter the colorless displaying pixel.
In the virtual-image display device according to the specific aspect, the transmissive-type liquid crystal panel turns the colorless displaying pixel into the transmitting state when the light source does not emit the light. In this case, during the sub-frame for observing the outside light, it is possible to utilize the displaying pixel, and it is possible to increase the brightness of the see-through image.
In the virtual-image display device according to the specific aspect, the light source generates white illumination light, the transmissive-type liquid crystal panel includes a sub-pixel for red, a sub-pixel for green, and a sub-pixel for blue, and performs modulation with the sub-pixel for each of the colors in accordance with the light emitted by the light source, and the transmissive-type liquid crystal panel turns the sub-pixel for each of the colors into a transmitting state when the light source does not emit light. In this case, during the sub-frame for observing an image, it is possible to display the red image light, the green image light, and the blue image light at the same time.
In the virtual-image display device according to the specific aspect, the light source generates white illumination light, the transmissive-type liquid crystal panel includes a sub-pixel for red, a sub-pixel for green, a sub-pixel for blue, and a colorless sub-pixel, and performs modulation with the sub-pixel for each of the colors in accordance with the light emitted by the light source, and the transmissive-type liquid crystal panel turns the colorless sub-pixel into a transmitting state when the light source does not emit light. In this case, during the sub-frame for observing an image, it is possible to display the red image light, the green image light, and the blue image light at the same time. In addition, during the sub-frame for observing the outside light, by operating at least the colorless sub-pixel, it is possible to observe the color image and the see-through image in a time-division manner.
In the virtual-image display device according to the specific aspect, an effective region of the ferroelectric liquid crystal plate is locally formed in a region that is opposed to the colorless sub-pixel of the transmissive-type liquid crystal panel. The colorless sub-pixel does not need to scatter the outside light, and only by locally forming the effective region of the ferroelectric liquid crystal plate in a region that is opposed to the sub-pixel for each of the colors, it is possible to cause the illumination light to enter the sub-pixel for each of the colors.
In the virtual-image display device according to the specific aspect, the transmissive-type liquid crystal panel turns the sub-pixel for each of the colors into a transmitting state when the light source does not emit light. In this case, during the sub-frame for observing the outside light, it is possible to utilize the sub-pixel for each of the color, and it is possible to increase the brightness of the see-through image.
In the virtual-image display device according to the specific aspect, in the scattering state, the ferroelectric liquid crystal plate causes the illumination light to be outputted to an outside of the light-guiding member, and in the transparent state, the ferroelectric liquid crystal plate transmits the outside light.
In the virtual-image display device according to the specific aspect, the colorless sub-pixel together with the sub-pixel for each of the colors is arrayed in a stripe pattern or a Bayer pattern to constitute a pixel.
In the virtual-image display device according to the specific aspect, in the scattering state, the ferroelectric liquid crystal plate causes the illumination light to be outputted to an outside of the light-guiding member, and in the transparent state, the ferroelectric liquid crystal plate transmits the outside light.
In the virtual-image display device according to the specific aspect, the ferroelectric liquid crystal plate is bonded to one of a pair of flat surfaces of a light-guiding plate provided at the light-guiding member, and is fixed to the light-guiding plate.
In the virtual-image display device according to the specific aspect, in the displaying state, the transmissive-type liquid crystal panel causes the illumination light that passes through the ferroelectric liquid crystal plate to enter to form image light, and in the non-display state, the transmissive-type liquid crystal panel transmits the outside light that passes through the ferroelectric liquid crystal plate.
In the virtual-image display device according to the specific aspect, the transmissive-type liquid crystal panel includes a liquid-crystal modulation member, and a pair of polarizing plates between which the liquid-crystal modulation member is interposed. The polarization directions of the pair of polarizing plates are set to intersect or set to be parallel, depending on a property of or a driving method of the liquid-crystal modulation member.
The virtual-image display device according to the specific aspect further includes a driving circuit configured to operate the light source, the ferroelectric liquid crystal plate, the transmissive-type liquid crystal panel, and the switching half-wave plate in a coordinated manner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-201297 | Nov 2023 | JP | national |
