Display device

Abstract

A display device according to the present disclosure comprises: a display panel that displays an image; a first optical system that projects the image as a real image; a second optical system that projects the image as a virtual image; and a control unit. The control unit controls the display of the image so that at least one from among the real image and the virtual image is projected.

Description

display device

[0001] The present disclosure relates to a display device.

[0002] 2. Description of the Related Art Conventionally, various display devices also called smart mirrors have been proposed (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-52916

[0004] The display device of the present disclosure comprises: a display panel that displays an image; a first optical system that projects the image displayed on the display panel as a real image; a second optical system that projects the image displayed on the display panel as a virtual image; and a control unit, wherein the control unit controls the display of the image so as to project at least one of the real image and the virtual image.

[0005] Objects, features, and advantages of the present disclosure will become clearer from the detailed description and drawings below.

[0023] Fig. 1 is a schematic diagram showing the configuration of a display device of the present disclosure.

[0024] Fig. 2 is a schematic diagram showing the configuration of a display device of a first embodiment.

[0025] Fig. 3 is a schematic diagram showing an example of an image displayed on a display panel.

[0026] Fig. 4 is a schematic diagram showing an example of an image displayed on a display panel.

[0027] Fig. 5 is a schematic diagram showing an example of an image displayed on a display panel.

[0028] Fig. 6 is a diagram for explaining the projection positions of a real image and a virtual image in the display device of the first embodiment.

[0029] Fig. 7 is a schematic diagram showing an example of the configuration of a display device of a second embodiment.

[0030] Fig. 8 is a diagram for explaining the projection positions of a real image and a virtual image in the display device of Fig. 5.

[0031] Fig. 9 is a schematic diagram showing an example of the configuration of a display device of a second embodiment.

[0032] Fig. 10 is a schematic diagram showing an example of the configuration of a display device of a second embodiment.

[0033] Fig. 11 is a schematic diagram showing the configuration of a smart mirror including a display device of the present disclosure.

[0006] Japanese Patent Application Laid-Open No. 2004-124222 discloses a display device that includes a display unit and an imaging unit, and displays an image generated on the display unit based on imaging data output by the imaging unit.

[0007] In conventional display devices, if a user's eyesight or eye accommodation function has deteriorated due to, for example, myopia, hyperopia, or presbyopia, it may be difficult for the user to view the image displayed on the display unit.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones. The drawings used in the following description show the main components of the display device of the present disclosure. The display device of the present disclosure may include well-known components not shown, such as a housing and holding members for each component. Furthermore, in some of the drawings, a Cartesian coordinate system XYZ is defined for convenience. The X-axis direction is also referred to as the width direction. The Y-axis direction is also referred to as the height direction. The Z-axis direction is also referred to as the depth direction or the emission direction.

[0009] FIG. 1 is a schematic diagram showing the configuration of a display device of the present disclosure. FIG. 2 is a schematic diagram showing the configuration of a display device of a first embodiment, FIGS. 3A, 3B, and 3C are schematic diagrams showing examples of images displayed on a display panel, and FIG. 4 is a diagram for explaining the projection positions of real and virtual images in the display device of the first embodiment. The arrows in FIG. 2 schematically show the optical paths of image light emitted from the display panel. For ease of illustration, FIG. 2 shows the optical paths of image light incident on the semi-transparent mirrors (first semi-transparent mirror, second semi-transparent mirror, and third semi-transparent mirror), the optical paths of image light transmitted through the semi-transparent mirrors, and the optical paths of image light reflected by the semi-transparent mirrors, shifted in the Y-axis direction. In the display device of this embodiment, the image light emitted from the display panel propagates substantially uniaxially. FIG. 4 shows a first optical system 3 and a second optical system 4, which have substantially the same schematic configuration.

[0010] As shown in FIG. 1, the display device 1 of this embodiment includes a display panel 2, a first optical system 3, a second optical system 4, and a control unit 15.

[0011] As shown in FIG. 2 , the display panel 2 has a display surface 2a and displays an image G on the display surface 2a. In other words, the display panel 2 emits image light of the image G from the display surface 2a. The display panel 2 may emit linearly polarized image light in the Z-axis direction (emission direction). The display panel 2 may emit linearly polarized image light having a polarization axis in a first direction. The linearly polarized light having a polarization axis in the first direction may be S-wave polarized light. The following describes a case where the display panel 2 emits S-wave polarized image light, but the present invention is not limited to this, and the display panel 2 may also emit P-wave polarized image light.

[0012] The display panel 2 may be a liquid crystal panel. The liquid crystal panel may be a known liquid crystal panel. The known liquid crystal panel may be, for example, an IPS (In-Plane Switching) type, an FFS (Fringe Field Switching) type, a VA (Vertical Alignment) type, an ECB (Electrically Controlled Birefringence) type, or the like.

[0013] The display device 1 may include an illuminator 7 that illuminates the display panel 2 in a planar manner. The illuminator 7 is also referred to as a backlight. The illuminator 7 may be an edge-lit backlight or a direct-lit backlight. An edge-lit backlight has one or more light sources arranged around the periphery of the display panel 2, and the light emitted from the light sources is guided by a light guide plate to the entire back surface of the display panel 2, where it is uniformly dispersed. A direct-lit backlight has multiple light sources arranged on the back side of the display panel 2, and irradiates the display panel 2 with light emitted from the multiple light sources. The light source of the illuminator 7 may be a cold cathode fluorescent lamp, a halogen lamp, a xenon lamp, or the like, or may be a light-emitting diode element, an organic light-emitting diode element, a semiconductor laser element, or the like. Note that the display panel 2 is not limited to a liquid crystal panel, and may be a self-luminous display panel including, for example, a light-emitting diode element, an organic light-emitting diode element, a semiconductor laser element, or the like. If the display panel 2 is a self-luminous display panel, the display device 1 does not need to include the illuminator 7.

[0014] The first optical system 3 projects the image G displayed on the display panel 2 as a real image R into the field of view of the user 17. As shown in Fig. 2 , the first optical system 3 includes a first semi-transmitting mirror 8, a second semi-transmitting mirror 9, a third semi-transmitting mirror 10, a first retardation plate 11, and a second retardation plate 12. The second semi-transmitting mirror 9, the first retardation plate 11, the first semi-transmitting mirror 8, the second retardation plate 12, and the third semi-transmitting mirror 10 are arranged in this order in the emission direction of the image light from the display panel 2.

[0015] The first semi-transmitting mirror 8 is located away from the display surface 2a of the display panel 2 in the emission direction of the image light. The first semi-transmitting mirror 8 may transmit a portion (approximately 50%) of the incident light and reflect the remaining portion (approximately 50%). The first semi-transmitting mirror 8 has a reflective surface 8a facing the first retardation film 11 and a reflective surface 8b facing the second retardation film 12. In this embodiment, the first semi-transmitting mirror 8 is a plane mirror (plane half mirror) whose reflective surfaces 8a and 8b are parallel or approximately parallel to the display surface 2a.

[0016] The first semi-transparent mirror 8 may be configured to include, for example, a substrate and a semi-transparent layer located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, inorganic glass, a resin material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The semi-transparent layer may be a metal thin film. The metal thin film may be configured from a metal material such as aluminum, chromium, or the like. The semi-transparent layer is not limited to a metal thin film and may be, for example, a dielectric multilayer film, or the like.

[0017] The first retardation plate 11 is located between the display panel 2 and the first semi-transmitting mirror 8. The second retardation plate 12 is located on the opposite side of the first semi-transmitting mirror 8 from the first retardation plate 11. The first retardation plate 11 and the second retardation plate 12 may be quarter-wave plates. The first retardation plate 11 and the second retardation plate 12 may be fixed to the first semi-transmitting mirror 8 by an optically clear adhesive such as an optically clear adhesive (OCA). The adhesive may be a material with small retardation (phase difference).

[0018] The second semi-transmitting mirror 9 is located between the display panel 2 and the first retardation film 11. The second semi-transmitting mirror 9 may transmit a portion of the incident light and reflect the remainder. The second semi-transmitting mirror 9 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIG. 2 , the second semi-transmitting mirror 9 may be a concave mirror having a concave reflecting surface 9a that faces the reflecting surface 8a of the first semi-transmitting mirror 8 across the first retardation film 11. At least a portion of the reflecting surface 9a of the second semi-transmitting mirror 9 may include a spherical, aspherical, or free-form surface shape.

[0019] The second semi-transparent mirror 9 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, a resin material, a glass material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The thin metal wires may be configured from a metal material, for example, aluminum, chromium, titanium oxide, or the like. The second semi-transparent mirror 9 can transmit polarized light oscillating in a direction perpendicular to the grid and can reflect polarized light oscillating in a direction parallel to the grid.

[0020] The third semi-transmitting mirror 10 is located on the opposite side of the second semi-transmitting mirror 9 across the first semi-transmitting mirror 8, the first retardation plate 11, and the second retardation plate 12. The third semi-transmitting mirror 10 may transmit a portion of the incident light and reflect the remainder. The third semi-transmitting mirror 10 may reflect polarized light having a polarization axis in a first direction (S-wave polarization) and transmit polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIG. 2 , the third semi-transmitting mirror 10 may be a concave mirror having a concave reflecting surface 10a facing the first semi-transmitting mirror 8 via the second retardation plate 12. At least a portion of the reflecting surface 10a of the third semi-transmitting mirror 10 may include a spherical, aspherical, or free-form surface shape.

[0021] Similar to the second semi-transparent mirror 9, the third semi-transparent mirror 10 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate.

[0022] The second optical system 4 projects the image G displayed on the display panel 2 as a virtual image V into the user's field of view. The second optical system 4 includes a first semi-transmitting mirror 8, a fourth semi-transmitting mirror 13, a fifth semi-transmitting mirror 14, a first retardation plate 11, and a second retardation plate 12. As shown in FIG. 2 , the fourth semi-transmitting mirror 13, the first retardation plate 11, the first semi-transmitting mirror 8, the second retardation plate 12, and the fifth semi-transmitting mirror 14 are arranged in this order in the direction of emission of the image light from the display panel 2. The first semi-transmitting mirror 8, the first retardation plate 11, and the second retardation plate 12 are the first semi-transmitting mirror 8, the first retardation plate 11, and the second retardation plate 12 of the first optical system 3, respectively, and therefore will not be described here.

[0023] The fourth semi-transmitting mirror 13 is located between the display panel 2 and the first retardation film 11. The fourth semi-transmitting mirror 13 may transmit a portion of the incident light and reflect the remainder. The fourth semi-transmitting mirror 13 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIG. 2 , the fourth semi-transmitting mirror 13 may be a concave mirror having a concave reflective surface 13a facing the first semi-transmitting mirror 8 across the first retardation film 11. At least a portion of the reflective surface 13a of the fourth semi-transmitting mirror 13 may include a spherical, aspherical, or free-form surface shape.

[0024] The fourth semi-transparent mirror 13 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate, similar to the second semi-transparent mirror 9 .

[0025] The fifth semi-transmitting mirror 14 is located on the opposite side of the first semi-transmitting mirror 8, the first retardation plate 11, and the second retardation plate 12 from the fourth semi-transmitting mirror 13. The fifth semi-transmitting mirror 14 may transmit a portion of the incident light and reflect the remainder. The fifth semi-transmitting mirror 14 may reflect polarized light having a polarization axis in a first direction (S-wave polarized light) and transmit polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarized light). As shown in FIG. 2 , the fifth semi-transmitting mirror 14 may be a concave mirror having a concave reflecting surface 14a facing the first semi-transmitting mirror 8 via the second retardation plate 12. At least a portion of the reflecting surface 14a of the fifth semi-transmitting mirror 14 may include a spherical, aspherical, or free-form surface shape.

[0026] The fifth semi-transparent mirror 14 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate, similar to the second semi-transparent mirror 9 .

[0027] The control unit 15 is connected to and controls each component of the display device 1. The components controlled by the control unit 15 include the display panel 2 and a drive unit 5 (see below) that controls the first optical system 3 and the second optical system 4. The control unit 15 can control the first optical system 3 and the second optical system 4 by controlling the drive unit 5. The control unit 15 may be configured to include one or more processors. The processor may include a general-purpose processor configured to load a specific program and execute a specific function, or a dedicated processor specialized for a specific process. The processor may include a programmable logic device (PLD). The control unit 15 may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together. The control unit 15 may include a memory unit that stores various information, programs for operating each component of the display device 1, and the like. The memory unit may be configured, for example, with a semiconductor memory. The memory unit may function as a work memory for the control unit 15.

[0028] The control unit 15 controls the display of the image G displayed on the display panel 2 so that at least one of a real image R and a virtual image V is projected. The image G displayed on the display panel 2 includes at least one of a first image G1 projected as a real image R into the field of view of the user 17 and a second image G2 projected as a virtual image V into the field of view of the user 17. The control unit 15 may display both the first image G1 and the second image G2 on the display panel 2 as shown in Fig. 3A, may display only the first image G1 as shown in Fig. 3B, or may display only the second image G2 as shown in Fig. 3C.

[0029] The display device 1 can project the image G displayed on the display panel 2 as at least one of a real image R and a virtual image V at a position different from the display surface 2a of the display panel 2. As a result, the user 17 can easily view the image G.

[0030] The control unit 15 may make the size of the first image G1 larger than the size of the second image G2. In the display device 1, the magnification ratio of the first image G1 by the first optical system 3 may be smaller than the magnification ratio of the second image G2 by the second optical system 4. By making the size of the first image G1 larger than the size of the second image G2, it is possible to make the size of the real image R projected into the field of view of the user 17 and the size of the virtual image V projected into the field of view of the user 17 approximately the same. The control unit 15 may invert the first image G1 or the second image G2 upside down or left to right.

[0031] The display device 1 may include a driver 5. The driver 5 controls the relative position of the display panel 2 and a focal point (object focal point) F on the display panel 2 side of the first optical system 3. The driver 5 controls at least one of the display panel 2 and the first optical system 3 so that the display panel 2 is positioned farther away from the object focal point F of the first optical system 3. In other words, the driver 5 controls at least one of the display panel 2 and the first optical system 3 so that the optical path length of the image light from the display panel 2 to the second semi-transmitting mirror 9 or the third semi-transmitting mirror 10 via the first semi-transmitting mirror 8 is longer than the focal lengths of the second semi-transmitting mirror 9 and the third semi-transmitting mirror 10. This enables the display device 1 to project a real image R into the field of view of the user 17 and to change the projection position of the real image R in the emission direction (Z-axis direction).

[0032] The driver 5 controls the relative position of the focal point F' (object focus) on the display panel 2 side of the second optical system 4 and the display panel 2. The driver 5 controls at least one of the display panel 2 and the second optical system 4 so that the display panel 2 is positioned closer than the object focus F' in the second optical system 4. In other words, the driver 5 controls at least one of the display panel 2 and the second optical system 4 so that the optical path length of the image light from the display panel 2 to the fourth semi-transmitting mirror 13 or the fifth semi-transmitting mirror 14 via the first semi-transmitting mirror 8 is shorter than the focal lengths of the fourth semi-transmitting mirror 13 and the fifth semi-transmitting mirror 14. This enables the display device 1 to project a virtual image V into the field of view of the user 17 and to change the projection position of the virtual image V in the emission direction (Z-axis direction).

[0033] The driving unit 5 may be configured, for example, by an electric slider, an electric cylinder, etc. The driving unit 5 may be configured so that the user 17 can manually control the relative positions of the object focal points F, F′ in the first optical system 3 and the second optical system 4 and the display panel 2.

[0034] When moving the display panel 2, the drive unit 5 may move the illuminator 7 together with the display panel 2 so that the distance between the display panel 2 and the illuminator 7 is maintained substantially constant. In this case, the amount of light irradiated onto the display panel 2 can be maintained substantially constant, thereby reducing fluctuations in the amount of image light emitted from the display panel 2. Therefore, changes in the luminance of the real image R and virtual image V viewed by the user 17 can be reduced.

[0035] The display device 1 may be configured to change the focal lengths of the second semi-transparent mirror 9, the third semi-transparent mirror 10, the fourth semi-transparent mirror 13, and the fifth semi-transparent mirror 14. The display device 1 may include, for example, a deformation unit that can deform the second semi-transparent mirror 9, the third semi-transparent mirror 10, the fourth semi-transparent mirror 13, and the fifth semi-transparent mirror 14 (changing the curvature, shape, etc. of the reflective surface 9 a). The deformation unit can change the focal lengths of the second semi-transparent mirror 9, the third semi-transparent mirror 10, the fourth semi-transparent mirror 13, and the fifth semi-transparent mirror 14 by deforming the second semi-transparent mirror 9, the third semi-transparent mirror 10, the fourth semi-transparent mirror 13, and the fifth semi-transparent mirror 14. The deformation unit may be configured, for example, by an electric slider, an electric cylinder, or the like. The deformation unit may constitute a part of the drive unit 5.

[0036] A description will be given of the traveling path of the image light incident on the first optical system 3. The image light incident on the first optical system 3 travels along a path P1 or a path P2, as shown in FIG.

[0037] The light traveling along path P1 will be described. The S-wave polarized image light (first linearly polarized light L1) emitted from the display panel 2 passes through the second semi-transparent mirror 9. The first linearly polarized light L1 passes through the first retardation plate 11 and is converted into first circularly polarized light C1. The first circularly polarized light C1 is incident on the first semi-transparent mirror 8. A portion (approximately 50%) of the first circularly polarized light C1 is reflected by the first semi-transparent mirror 8 and converted into second circularly polarized light C2. The second circularly polarized light C2 passes through the first retardation plate 11 and is converted into second linearly polarized light L2, the polarization axis of which is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The second linearly polarized light L2 is reflected by the second semi-transparent mirror 9 and is converted into third linearly polarized light L3, the polarization axis of which is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The third linearly polarized light L3 passes through the first retardation plate 11 and is converted into third circularly polarized light C3. The third circularly polarized light C3 is incident on the first semi-transparent mirror 8. A portion (approximately 50%) of the third circularly polarized light C3 passes through the first semi-transparent mirror 8. The third circularly polarized light C3 that passed through the first semi-transparent mirror 8 passes through the second retardation plate 12 and is converted into fourth linearly polarized light L4 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-polarized light). The fourth linearly polarized light L4 passes through the third semi-transparent mirror 10 and is emitted to the outside.

[0038] The light traveling along path P2 will now be described. The remainder (approximately 50%) of the light of the first circularly polarized light C1 incident on the first semi-transparent mirror 8 is transmitted through the first semi-transparent mirror 8. The light of the first circularly polarized light C1 transmitted through the first semi-transparent mirror 8 is transmitted through the second retardation plate 12 and converted into light of fifth linearly polarized light L5 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The light of the fifth linearly polarized light L5 is reflected by the third semi-transparent mirror 10 and converted into light of sixth linearly polarized light L6 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The light of the sixth linearly polarized light L6 is transmitted through the second retardation plate 12 and converted into light of fourth circularly polarized light C4. The light of the fourth circularly polarized light C4 is incident on the first semi-transparent mirror 8. A portion (approximately 50%) of the light of the fourth circularly polarized light C4 is reflected by the first semi-transparent mirror 8 and converted into light of fifth circularly polarized light C5. The fifth circularly polarized light C5 passes through the second retardation plate 12 and is converted into seventh linearly polarized light L7 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-polarized light). The seventh linearly polarized light L7 passes through the third semi-transparent mirror 10 and is emitted to the outside.

[0039] The image light incident on the first optical system 3 travels along path P1 or path P2 and is emitted to the outside. As a result, the amount of image light emitted via the first optical system 3 is approximately 50% of the amount of image light incident on the first optical system 3. Since the first optical system 3 has a relatively high light utilization efficiency, the display device 1 can improve the brightness of the real image R visually recognized by the user.

[0040] The driver 5 may control the first optical system 3 so that the focal length of the second semi-transmitting mirror 9 and the focal length of the third semi-transmitting mirror 10 are approximately equal. Furthermore, the driver 5 may control at least one of the display panel 2 and the first optical system 3 so that the distance between the first semi-transmitting mirror 8 and the second semi-transmitting mirror 9 and the distance between the first semi-transmitting mirror 8 and the third semi-transmitting mirror 10 are approximately equal, and the optical path length between the display panel 2 and the second semi-transmitting mirror 9 or the third semi-transmitting mirror 10 (i.e., the distance between the display panel 2 and the third semi-transmitting mirror 10) is longer than the focal lengths of the second semi-transmitting mirror 9 and the third semi-transmitting mirror 10. In this case, the real image formed by the image light traveling along path P1 and the real image formed by the image light traveling along path P2 coincide with each other, thereby improving the display quality of the real image R viewed by the user 17. The drive unit 5 may set the ratio of the focal length of the third semi-transparent mirror 10 to the focal length of the second semi-transparent mirror 9 to 0.9 to 1.1, or 0.95 to 1.05. The drive unit 5 may also set the ratio of the distance between the first semi-transparent mirror 8 and the third semi-transparent mirror 10 to the distance between the first semi-transparent mirror 8 and the second semi-transparent mirror 9 to 0.9 to 1.1, or 0.95 to 1.05.

[0041] 2, the image light incident on the second optical system 4 travels along paths similar to paths P1 and P2 of the image light incident on the first optical system 3, and therefore a description thereof will be omitted. The amount of image light emitted via the second optical system 4 is approximately 50% of the amount of image light incident on the second optical system 4. Since the second optical system 4 has a relatively high light utilization efficiency, the display device 1 can improve the brightness of the virtual image V viewed by the user 17.

[0042] The driver 5 may control the second optical system 4 so that the focal length of the fourth semi-transmitting mirror 13 and the focal length of the fifth semi-transmitting mirror 14 are approximately equal. Furthermore, the driver 5 may control at least one of the display panel 2 and the second optical system 4 so that the distance between the first semi-transmitting mirror 8 and the fourth semi-transmitting mirror 13 and the distance between the first semi-transmitting mirror 8 and the fifth semi-transmitting mirror 14 are approximately equal, and the optical path length between the display panel 2 and the fourth semi-transmitting mirror 13 or the fifth semi-transmitting mirror 14 (i.e., the distance between the display panel 2 and the fifth semi-transmitting mirror 14) is longer than the focal lengths of the fourth semi-transmitting mirror 13 and the fifth semi-transmitting mirror 14. In this case, the virtual image formed by the image light traveling along path P1 and the virtual image formed by the image light traveling along path P2 coincide with each other, thereby improving the display quality of the virtual image V viewed by the user 17. The drive unit 5 may set the ratio of the focal length of the fifth semi-transparent mirror 14 to the focal length of the fourth semi-transparent mirror 13 to 0.9 to 1.1, or 0.95 to 1.05. The drive unit 5 may set the ratio of the distance between the first semi-transparent mirror 8 and the fifth semi-transparent mirror 14 to the distance between the first semi-transparent mirror 8 and the fourth semi-transparent mirror 13 to 0.9 to 1.1, or 0.95 to 1.05.

[0043] 2 shows an example in which the first optical system 3 is positioned higher in the height direction (Y-axis direction) than the second optical system 4, but is not limited to this. The first optical system 3 may be positioned lower in the height direction (Y-axis direction) than the second optical system 4, or may overlap with the second optical system 4 when viewed in the width direction (X-axis direction).

[0044] The first optical system 3 and the second optical system 4 are uniaxial (on-axis) optical systems in which the optical axis of the incident light and the optical axis of the outgoing light are substantially aligned. Therefore, the display device 1 can reduce distortion, brightness unevenness, and the like of the real image R and the virtual image V viewed by the user 17. Furthermore, the design of the first optical system 3 and the second optical system 4 is simplified, and the focus, focal length, and the like of the first optical system 3 and the second optical system 4 are easily controlled.

[0045] The display device 1 may include an imaging unit 16. The imaging unit 16 is configured to capture an image of the face or head of a user 17 of the display device 1 and output the captured image data to the control unit 15. The user 17 may be located in front of the display device 1. In other words, the user 17 may be located away from the display device 1 in the Z-axis direction (the direction in which image light is emitted from the display panel 2).

[0046] The imaging unit 16 may be located within the housing of the display device 1. The position of the imaging unit 16 is arbitrary within the housing. The imaging unit 16 may be located between the first optical system 3 and the second optical system 4 in the height direction (Y-axis direction). The imaging unit 16 may be located above or below the first optical system 3 and the second optical system 4 in the height direction.

[0047] The imaging unit 16 may include a camera. The camera may include, for example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) imaging element. The camera may be a visible light camera. The camera may have both visible light and infrared camera functions. The camera may be a monocular camera or a stereo camera.

[0048] The imaging unit 16 may not include a camera, but may be connected to an external camera. The imaging unit 16 and the external camera may be connected via wired communication and / or wireless communication. The imaging unit 16 may include an input terminal that inputs an imaging signal (imaging data) from an external camera. The external camera may be directly connected to the input terminal. The external camera may be indirectly connected to the input terminal via a shared network. The imaging unit 16 may output the imaging data input to the input terminal to the control unit 15.

[0049] The control unit 15 may display the image G on the display surface 2a of the display panel 2 based on the imaging data acquired from the imaging unit 16. In this case, a smart mirror including the display device 1 can be realized.

[0050] The control unit 15 may perform local dimming control of the illuminator 7 in accordance with the image G displayed on the display panel 2. In this case, it becomes possible to project a clear real image R and virtual image V with improved contrast into the field of view of the user 17.

[0051] Next, the projection positions of the real image R and the virtual image V within the visual field of the user 17 of the display device 1 will be described.

[0052] A case where a real image R is projected into the visual field of the user 17 will be described. As shown in FIG. 4 , the distance between the eye of the user 17 and the third semi-transparent mirror 10 is A (mm), the distance between the first semi-transparent mirror 8 and the second semi-transparent mirror 9 and the distance between the first semi-transparent mirror 8 and the third semi-transparent mirror 10 are B (mm), and the distance between the display panel 2 and the second semi-transparent mirror 9 is C (mm). Furthermore, the focal lengths of the second semi-transparent mirror 9 and the third semi-transparent mirror 10 are f (mm). Table 1 shows an example of a combination of the distances A, B, and C and the focal length f when a real image R is projected into the visual field of the user 17. The display device 1 of this embodiment is not limited to the example shown in Table 1.

[0053]

[0054] The optical path length a (mm) between the display panel 2 and the reflecting surfaces 9a, 10a that reflect the image light emitted from the display panel 2 is expressed as a = 2 × B + C. In the example of Table 1, the optical path length a is 290 mm. Since the optical path length a (mm) is greater than the focal length f (mm), the user 17 can see the real image R. Let b be the distance between the second semi-transparent mirror 9 and the real image R. Ｒ (mm), the distance b Ｒ is expressed by the following formula (1): Ｒ =1 / (1 / f-1 / a)...(1)

[0055] In the example of Table 1, the distance between the eye of the user 17 and the second semi-transparent mirror 9 (i.e., A+2×B) is 680 mm, whereas the distance between the eye of the user 17 and the real image R (i.e., A+2×B−b Ｒ ) is 36 mm. Therefore, the user 17 visually perceives the real image R closer than the second semi-transparent mirror 9 and the third semi-transparent mirror 10. The magnification m of the real image R relative to the first image G1 is m=b ＲIn the example of Table 1, the magnification m is 2.2.

[0056]

[0057] A case where a virtual image V is projected into the field of view of a user 17 will be described. As shown in FIG. 4 , the distance between the eye of the user 17 and the fifth semi-transparent mirror 14 is A (mm), the distance between the first semi-transparent mirror 8 and the fourth semi-transparent mirror 13 and the distance between the first semi-transparent mirror 8 and the fifth semi-transparent mirror 14 is B (mm), and the distance between the display panel 2 and the fourth semi-transparent mirror 13 is C (mm). Furthermore, the focal length of the fourth semi-transparent mirror 13 and the fifth semi-transparent mirror 14 is f (mm). Table 2 shows an example of a combination of the distances A, B, C, and the focal length f when a virtual image V is projected into the field of view of the user 17. The display device 1 of this embodiment is not limited to the example shown in Table 2.

[0058] In the example of Table 2, the optical path length a (mm) is 153 mm. Since the optical path length a is smaller than the focal length f, the user 17 can see the virtual image V. Let b be the distance between the second semi-transparent mirror 9 and the virtual image V. Ｖ (mm), the distance b Ｖ is expressed by the following formula (2): Ｖ =1 / (1 / a-1 / f)...(2)

[0059] In the example of Table 2, the distance between the eye of the user 17 and the second semi-transparent mirror 9 (i.e., A+2×B) is 406 mm, whereas the distance between the eye of the user 17 and the virtual image V (i.e., A+2×B+b Ｖ ) is 1057 mm. Therefore, the user 17 visually recognizes the virtual image V at a distance farther than the second semi-transparent mirror 9. The magnification m of the virtual image V with respect to the second image G2 is m=b Ｖ In the example of Table 2, the magnification m is 4.3.

[0060] Next, a display device according to a second embodiment of the present disclosure will be described. FIG. 5 is a schematic diagram illustrating an example of the configuration of the display device according to the second embodiment. FIG. 6 is a diagram for explaining the projection positions of real and virtual images in the display device of FIG. 5. FIGS. 7 and 8 are schematic diagrams illustrating an example of the configuration of the display device according to the second embodiment. The arrows in FIGS. 5, 7, and 8 schematically indicate the optical paths of image light emitted from the display panel. In FIGS. 5, 7, and 8, for ease of illustration, the optical paths of the image light incident on the semi-transparent mirrors (first semi-transparent mirror, second semi-transparent mirror, and third semi-transparent mirror) and the optical paths of the image light reflected by the semi-transparent mirrors are shown shifted in the Y-axis direction. In the display device according to this embodiment, the image light emitted from the display panel propagates substantially on a single axis. The display device according to the second embodiment differs from the display device according to the first embodiment in the configurations of the first and second optical systems, but otherwise has the same configuration. Therefore, the same reference numerals as those in the display device according to the first embodiment are used for the similar components, and detailed descriptions thereof will be omitted.

[0061] As shown in FIG. 1, the display device 1A of this embodiment includes a display panel 2, a first optical system 18, a second optical system 19, and a control unit 15.

[0062] The first optical system 18 projects the image G displayed on the display panel 2 as a real image R into the field of view of the user 17. The first optical system 18 includes a first semi-transmitting mirror 20, a second semi-transmitting mirror 21, a first retardation plate 22, and a second retardation plate 23. As shown in Fig. 5 , the first retardation plate 22, the first semi-transmitting mirror 20, the second retardation plate 23, and the second semi-transmitting mirror 21 are arranged in this order in the Z-axis direction (the direction in which the image light is emitted from the display panel 2).

[0063] The first semi-transmitting mirror 20 is located away from the display surface 2a of the display panel 2 in the emission direction of the image light. The first semi-transmitting mirror 20 may transmit a portion (approximately 50%) of the incident light and reflect the remaining portion (approximately 50%). As shown in FIG. 5 , the first semi-transmitting mirror 20 may be a plane mirror having a reflective surface 20a facing the first retardation plate 22 and a reflective surface 20b facing the second retardation plate 23. The first semi-transmitting mirror 20 is also referred to as a plane half mirror. The reflective surfaces 20a and 20b may be parallel or approximately parallel to the display surface 2a.

[0064] The first semi-transparent mirror 20 may be configured to include, for example, a substrate and a semi-transparent layer located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, inorganic glass, a resin material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The semi-transparent layer may be a metal thin film. The metal thin film may be configured from a metal material such as aluminum, chromium, or the like. The semi-transparent layer is not limited to a metal thin film and may be, for example, a dielectric multilayer film, or the like.

[0065] The first retardation plate 22 is located between the display panel 2 and the first semi-transmitting mirror 20. The second retardation plate 23 is located on the opposite side of the first semi-transmitting mirror 20 from the first retardation plate 22. The first retardation plate 22 and the second retardation plate 23 may be quarter-wave plates. The first retardation plate 22 and the second retardation plate 23 may be fixed to the first semi-transmitting mirror 20 by an optically transparent adhesive such as an optically clear adhesive (OCA). The adhesive may be a material with small retardation (phase difference).

[0066] The second semi-transmitting mirror 21 is positioned away from the second retardation plate 23 in the Z-axis direction (the direction in which image light is emitted from the display panel 2). The second semi-transmitting mirror 21 may transmit a portion of the incident light and reflect the remainder. The second semi-transmitting mirror 21 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction perpendicular to the first direction (P-wave polarization). As shown in FIG. 5 , the second semi-transmitting mirror 21 may be a concave mirror having a concave reflecting surface 21a facing the reflecting surface 20b of the first semi-transmitting mirror 20 via the second retardation plate 23. At least a portion of the reflecting surface 21a of the second semi-transmitting mirror 21 may include a spherical, aspherical, or free-form surface shape.

[0067] The second semi-transparent mirror 21 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, a resin material, a glass material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The thin metal wires may be configured from a metal material, for example, aluminum, chromium, titanium oxide, or the like. The second semi-transparent mirror 21 can transmit polarized light oscillating in a direction perpendicular to the grid and can reflect polarized light oscillating in a direction parallel to the grid.

[0068] The second optical system 19 projects the image G displayed on the display panel 2 as a virtual image V into the field of view of the user 17. The second optical system 19 includes a first semi-transmitting mirror 20, a third semi-transmitting mirror 24, a first retardation plate 22, and a second retardation plate 23. As shown in FIG. 5 , the third semi-transmitting mirror 24, the first retardation plate 22, the first semi-transmitting mirror 20, and the second retardation plate 23 are arranged in this order in the Z-axis direction (the direction in which the image light is emitted from the display panel 2). The first semi-transmitting mirror 20, the first retardation plate 22, and the second retardation plate 23 are the first semi-transmitting mirror 20, the first retardation plate 22, and the second retardation plate 23 of the first optical system 18, respectively, and therefore will not be described here.

[0069] The third semi-transmitting mirror 24 is located between the display panel 2 and the first retardation film 22. The third semi-transmitting mirror 24 may transmit a portion of the incident light and reflect the remainder. The third semi-transmitting mirror 24 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIG. 5 , the third semi-transmitting mirror 24 may be a concave mirror having a concave reflecting surface 24a facing the reflecting surface 20a of the first semi-transmitting mirror 20 across the first retardation film 22. At least a portion of the reflecting surface 24a of the third semi-transmitting mirror 24 may include a spherical, aspherical, or free-form surface shape.

[0070] Similar to the second semi-transparent mirror 21, the third semi-transparent mirror 24 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate.

[0071] The control unit 15 controls the display of the image G displayed on the display panel 2 so as to project at least one of a real image R and a virtual image V. The display device 1 can project the image G displayed on the display panel 2 as at least one of a real image R and a virtual image V at a position different from the display surface 2a of the display panel 2. As a result, the user 17 can easily view the image G.

[0072] The travel path of the image light incident on the first optical system 18 will now be described. The display panel 2 emits S-wave polarized image light (first linearly polarized light L1). The first linearly polarized image light L1 emitted from the display panel 2 passes through the first retardation plate 22 and is converted into first circularly polarized light C1. A portion (approximately 50%) of the first circularly polarized light C1 transmitted through the first retardation plate 22 passes through the first semi-transparent mirror 20. The first circularly polarized light C1 transmitted through the first semi-transparent mirror 20 passes through the second retardation plate 23 and is converted into second linearly polarized light L2 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The second linearly polarized light L2 enters the second semi-transparent mirror 21. The second linearly polarized light L2 incident on the second semi-transparent mirror 21 is reflected by the second semi-transparent mirror 21 and converted into third linearly polarized light L3. The third linearly polarized light L3 passes through the second retardation plate 23 and is converted into the second circularly polarized light C2. A portion (approximately 50%) of the second circularly polarized light C2 that passed through the second retardation plate 23 is reflected by the first semi-transparent mirror 20 and converted into the third circularly polarized light C3. The third circularly polarized light C3 passes through the second retardation plate 23 and is converted into the fourth linearly polarized light L4 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The fourth linearly polarized light L4 passes through the second semi-transparent mirror 21 and is emitted to the outside. The amount of image light that passes through the first optical system 18 is approximately 25% of the amount of image light that entered the first optical system 18.

[0073] The travel path of the image light incident on the second optical system 19 will now be described. The S-wave polarized image light (first linearly polarized light L1) emitted from the display panel 2 passes through the third semi-transparent mirror 24. The first linearly polarized light L1 that passed through the third semi-transparent mirror 24 passes through the first retardation plate 22 and is converted into first circularly polarized light C1. A portion (approximately 50%) of the first circularly polarized light C1 that passed through the first retardation plate 22 passes through the first semi-transparent mirror 20, and the remaining portion (approximately 50%) of the first circularly polarized light C1 that passed through the first retardation plate 22 is reflected by the first semi-transparent mirror 20 and converted into fourth circularly polarized light C4. The fourth circularly polarized light C4 passes through the first retardation plate 22 and is converted into fifth linearly polarized light L5 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The fifth linearly polarized light L5 is incident on the third semi-transparent mirror 24. The light of the fifth linearly polarized light L5 incident on the third semi-transparent mirror 24 is reflected by the third semi-transparent mirror 24 and converted into light of the sixth linearly polarized light L6. A portion (approximately 50%) of the sixth linearly polarized light L6 is transmitted through the first retardation plate 22, the first semi-transparent mirror 20, and the second retardation plate 23, and is emitted to the outside. The amount of image light emitted via the second optical system 19 is approximately 25% of the amount of image light incident on the second optical system 19.

[0074] The display device 1A may be configured to be able to change the focal lengths of the second semi-transparent mirror 21 and the third semi-transparent mirror 24. The display device 1A may include, for example, a deformation unit that can deform the second semi-transparent mirror 21 and the third semi-transparent mirror 24 (changing the curvature, shape, etc. of the reflecting surfaces 21 a, 24 a). The deformation unit can change the focal lengths of the second semi-transparent mirror 21 and the third semi-transparent mirror 24 by deforming the second semi-transparent mirror 21 and the third semi-transparent mirror 24. The deformation unit may be configured, for example, by an electric slider, an electric cylinder, etc. The deformation unit may constitute a part of the drive unit 5.

[0075] The driver 5 controls the relative position of the display panel 2 and a focal point (object focal point) F on the display panel 2 side of the first optical system 18. The driver 5 controls at least one of the display panel 2 and the first optical system 18 so that the display panel 2 is positioned farther away from the object focal point F of the first optical system 18. In other words, the driver 5 controls at least one of the display panel 2 and the first optical system 18 so that the optical path length of the image light from the display panel 2 to the second semi-transmitting mirror 21 via the first semi-transmitting mirror 20 is longer than the focal length of the second semi-transmitting mirror 21. This enables the display device 1A to project a real image R into the field of view of the user 17 and to change the projection position of the real image R in the emission direction (Z-axis direction).

[0076] The driver 5 may control at least one of the display panel 2 and the first optical system 18 so that the distance between the display panel 2 and the second semi-transmitting mirror 21 is greater than the focal length of the first optical system 18 on the display panel 2 side. This makes it possible to make the optical path length of the image light from the display panel 2, via the first semi-transmitting mirror 20, to the second semi-transmitting mirror 21 greater than the focal length of the second semi-transmitting mirror 21.

[0077] The driver 5 controls the relative position of the focal point (object focus) F' on the display panel 2 side of the second optical system 19 and the display panel 2. The driver 5 controls at least one of the display panel 2 and the second optical system 19 so that the display panel 2 is positioned closer than the object focus F' in the second optical system 19. In other words, the driver 5 controls at least one of the display panel 2 and the second optical system 19 so that the optical path length of the image light from the display panel 2, via the first semi-transparent mirror 20, to the third semi-transparent mirror 24 is shorter than the focal length of the third semi-transparent mirror 24. This allows the display device 1A to project a virtual image V into the field of view of the user 17 and also allows the projection position of the virtual image V to be changed in the emission direction (Z-axis direction).

[0078] The driver 5 may control at least one of the display panel 2 and the second optical system 19 so that the sum of twice the distance between the first semi-transparent mirror 20 and the third semi-transparent mirror 24 and the distance between the display panel 2 and the third semi-transparent mirror 24 is smaller than the focal length of the second optical system 19 on the display panel 2 side. This makes it possible to make the optical path length of the image light from the display panel 2, via the first semi-transparent mirror 20, to the third semi-transparent mirror 24 shorter than the focal length of the third semi-transparent mirror 24.

[0079] The first optical system 18 and the second optical system 19 are uniaxial (on-axis) optical systems in which the optical axis of the incident light and the optical axis of the outgoing light are substantially aligned. Therefore, the display device 1A can reduce distortion and brightness unevenness of the real image R and the virtual image V viewed by the user 17. Furthermore, the design of the first optical system 18 and the second optical system 19 is simplified, and the focus, focal length, and other aspects of the first optical system 18 and the second optical system 19 can be easily controlled.

[0080] Next, the projection positions of the real image R and the virtual image V within the field of view of the user 17 of the display device 1A will be described. As shown in FIG. 6 , the distance between the eye of the user 17 and the second semi-transparent mirror 21 is A (mm), the distance between the first semi-transparent mirror 20 and the second semi-transparent mirror 21 is B (mm), the distance between the first semi-transparent mirror 20 and the third semi-transparent mirror 24 is C (mm), and the distance between the display panel 2 and the third semi-transparent mirror 24 is D (mm). Furthermore, the focal length of the second semi-transparent mirror 21 and the third semi-transparent mirror 24 is f (mm). Table 3 shows an example of a combination of the distances A, B, C, and D and the focal length f. The display device 1A of this embodiment is not limited to the example shown in Table 3.

[0081]

[0082] The projection position of the real image R will now be described. The optical path length a (mm) between the display panel 2 and the reflecting surface 21a that reflects the image light emitted from the display panel 2 is expressed as a = B + C + D. In the example of Table 3, the optical path length a is 300 mm. Since the optical path length a (mm) is greater than the focal length f (mm), the user 17 can view the real image R. Let b be the distance between the second semi-transparent mirror 21 and the real image R. Ｒ (mm), the distance b Ｒis expressed by the above formula (1). In the example of Table 3, the distance b Ｒ becomes 600 mm.

[0083] In the example of Table 3, the distance A between the eye of the user 17 and the second semi-transparent mirror 21 is 400 mm, whereas the distance between the eye of the user 17 and the real image R (i.e., A+2×B−b Ｒ ) is 100 mm. Therefore, the user 17 visually perceives the real image R closer than the second semi-transparent mirror 21. The magnification m of the real image R relative to the first image G1 is m=b Ｒ In the example of Table 3, the magnification ratio m is 2.0.

[0084] The projection position of the virtual image V will now be described. The optical path length a (mm) between the display panel 2 and the reflecting surface 24a that reflects the image light emitted from the display panel 2 is expressed as a = 2 × C + D. In the example of Table 1, the optical path length a is 152 mm. Since the optical path length a is smaller than the focal length f, the user 17 can view the virtual image V. Let b be the distance between the third semi-transparent mirror 24 and the virtual image V. Ｖ (mm), the distance b Ｖ is expressed by the above formula (2).

[0085] In the example of Table 3, the distance between the eye of the user 17 and the third semi-transparent mirror 24 (i.e., A+B+C) is 552 mm, whereas the distance between the eye of the user 17 and the virtual image V (i.e., A+B+C+b Ｖ ) is 1185 mm. Therefore, the user 17 visually recognizes the virtual image V at a distance farther than the third semi-transparent mirror 24. The magnification m of the virtual image V with respect to the second image G2 is m=b Ｖ In the example of Table 3, the magnification m is 4.2.

[0086] The display device 1A of the present embodiment is not limited to the configuration shown in FIG. 5 , as long as the second semi-transmitting mirror 21 faces the first semi-transmitting mirror 20 via the first retardation plate 22 or the second retardation plate 23, and the third semi-transmitting mirror 24 faces the first semi-transmitting mirror 20 via the first retardation plate 22 or the second retardation plate 23. The display device 1A may also be configured as shown in FIG. 7 , in which the second semi-transmitting mirror 21 and the third semi-transmitting mirror 24 face the first semi-transmitting mirror 20 via the second retardation plate 23. The traveling path of the image light in the display device 1A of FIG. 7 is similar to the traveling path of the image light incident on the first optical system 18 of FIG. 5 , and therefore a description thereof will be omitted. Even with the configuration shown in FIG. 7 , the display device 1A can allow the user 17 to view the real image R and the virtual image V.

[0087] As shown in Fig. 8, the display device 1A may have a configuration in which the second semi-transparent mirror 21 and the third semi-transparent mirror 24 face the first semi-transparent mirror 20 via the first retardation plate 22. The traveling path of the image light in the display device 1A in Fig. 8 is similar to the traveling path of the image light incident on the second optical system 19 in Fig. 5, and therefore a description thereof will be omitted. Even with the configuration shown in Fig. 8, the display device 1A can allow the user 17 to view the real image R and the virtual image V.

[0088] 5 , when the second semi-transparent mirror 21 and the third semi-transparent mirror 24 are located on opposite sides of the first semi-transparent mirror 20, the display device 1A can reduce positional interference between a part of the drive unit 5 that controls the second semi-transparent mirror 21 and another part that controls the third semi-transparent mirror 24. As a result, it becomes easier to control the second semi-transparent mirror 21 and the third semi-transparent mirror 24, and it becomes possible for the user 17 to properly view the real image R and the virtual image V.

[0089] 5 and 7 , in the display device 1A, when the second semi-transmitting mirror 21 is spaced apart from the second retardation plate 23 in the emission direction (Z-axis direction), the adjustment range of the distance between the first semi-transmitting mirror 20 and the second semi-transmitting mirror 21 (distance B shown in FIG. 6 ) can be increased, and it becomes easy to make the optical path length a (the sum of distances B, C, and D shown in FIG. 6 ) between the display panel 2 and the reflecting surface 21 a of the second semi-transmitting mirror 21 longer than the focal length f of the second semi-transmitting mirror 21. As a result, the adjustment range of the projection position of the real image R can be increased.

[0090] The display panel 2 may display a mixed image including a left-eye image and a right-eye image having parallax with respect to each other, and may emit image light of the mixed image. The display device 1, 1A may include an optical element located in the optical path of the image light emitted from the display panel 2 and defining the respective ray directions of the image light for the left eye and the image light for the right eye. The optical element may be configured to cause at least a portion of the image light for the left eye to reach the left eye of the user 17, and to cause at least a portion of the image light for the right eye to reach the right eye of the user 17. In this case, the display device 1, 1A allows the user 17 to view a three-dimensional real image R and a three-dimensional virtual image V.

[0091] The optical element may be a parallax barrier or a lenticular lens. The parallax barrier may be formed of a liquid crystal panel. The optical element may be located before the first optical system 3, 18 and the second optical system 4, 19 in the emission direction of the image light from the display panel 2 (i.e., between the display panel 2 and the first optical system 3, 18 and the second optical system 4, 19), or may be located after the first optical system 3, 18 and the second optical system 4, 19.

[0092] A smart mirror including the display device of the present disclosure will be described below. Fig. 9 is a schematic diagram showing the configuration of a smart mirror including the display device of the present disclosure.

[0093] The display device 1, 1A may constitute a part of a smart mirror 50, as shown in Fig. 9. The smart mirror 50 may be used, for example, when a user 17 applies makeup or styles their hair.

[0094] The imaging unit 16 may capture an image of the user 17's face, and the display panel 2 may display an image G (see FIGS. 3A, 3B, and 3C) including an image of the user 17's face based on the imaging data output from the imaging unit 16. The first optical system 3, 18 may project a first image G1 as a real image R into the user 17's field of view, and the second optical system 4, 19 may project a second image G2 as a virtual image V into the user 17's field of view. The drive unit 5 may control the relative position of the object focal points F, F' and the display panel 2 to change the projection positions of the real image R and the virtual image V within the user 17's field of view in the depth direction (Z-axis direction). With the smart mirror 50 including the display device 1, 1A, the user 17 can properly view the real image R or virtual image V including the user 17's face without using vision correction devices such as glasses, even if their eyesight or eye accommodation function is impaired, making it easier to apply makeup, style their hair, and so on. This improves convenience for the user 17.

[0095] The smart mirror 50 may enlarge or reduce the real image R or the virtual image V in response to an instruction from the user 17. In this case, the user 17 can more easily apply makeup, style their hair, and so on, thereby improving convenience for the user 17. The smart mirror 50 may flip the real image R or the virtual image V left and right in response to an instruction from the user 17. In this case, the user 17 can more easily apply makeup, style their hair, and so on, and can more easily check their own appearance, thereby improving convenience for the user 17.

[0096] The smart mirror 50 may include an input interface 52 that accepts instructions from the user 17. The input interface 52 may be configured with, for example, buttons, a keyboard, etc. The input interface 52 may be a microphone that allows voice input, or a sensor that allows gesture input. The sensor may be, for example, an infrared sensor, an ultrasonic sensor, a millimeter wave sensor, etc.

[0097] The smart mirror 50 may store the eye condition of the user 17 (e.g., eyesight, eye accommodation function, etc.). The smart mirror 50 may identify the user 17 and control the projection of a real image R, a virtual image V, or both the real image R and the virtual image V into the user's field of view according to the eye condition of the user 17. The smart mirror 50 may identify the user 17 based on information input to the input interface 52. The smart mirror 50 may identify the user 17 by performing facial recognition based on the imaging data output from the imaging unit 16. The smart mirror 50 may control the projection of a real image R, a virtual image V, or both the real image R and the virtual image V according to the user 17 based on the identification information of the user 17. The identification information may include, for example, information on the user's 17's past display history.

[0098] The smart mirror 50 may be connected to an external server 53 via a network such as the Internet or a local area network (LAN). The smart mirror 50 may acquire makeup information corresponding to the user 17 via the server 53 and present the acquired makeup information to the user 17. The smart mirror 50 may include an audio output unit such as a speaker, and may present the makeup information to the user 17 by audio output from the audio output unit. The smart mirror 50 may present the makeup information to the user 17 by projecting a real image R or a virtual image V including the makeup information into the field of view of the user 17. The smart mirror 50 may present the makeup information to the user 17 using both the audio output from the audio output unit and the real image R or virtual image V projected into the field of view of the user 17.

[0099] The smart mirror 50 may generate a pseudo image of the user 17 wearing makeup specified by the makeup information, based on the image of the user 17 captured by the imaging unit 16 and the makeup information acquired from the server 53. As shown in Fig. 9 , the smart mirror 50 may be configured to allow the user 17 to view the generated pseudo image as a real image R or a virtual image V.

[0100] The smart mirror 50 may be configured to be able to communicate with the makeup advisor 54 via the server 53. The smart mirror 50 may generate a pseudo image of the user 17 by applying pseudo makeup remotely operated by the makeup advisor 54 to an image of the user 17 captured by the imaging unit 16. The smart mirror 50 may allow the user 17 to view the generated pseudo image as a real image R or a virtual image V, as shown in FIG. 9 . The smart mirror 50 may store image data of the pseudo image in the memory unit of the control unit 15. The smart mirror 50 may save image data of the pseudo image in the server 53. The smart mirror 50 may read image data of the pseudo image from the memory unit or the server 53, and allow the user 17 to view the read pseudo image as a real image R or a virtual image V. The smart mirror 50 may allow the user 17 to view a mixed image, in which the image of the user 17 captured by the imaging unit 16 and the pseudo image read from the server 53 are arranged in the width direction (X-axis direction) or height direction (Y-axis direction), as a real image R or a virtual image V. In this case, the user 17 can apply makeup while referring to the real image R or virtual image V of the mixed image, thereby improving the convenience of the user 17. The smart mirror 50 may transmit image data of the pseudo image to others via a network.

[0101] The smart mirror 50 may detect the position, orientation, movement, etc. of the makeup tool 51 held by the user 17 based on the imaging data output from the imaging unit 16. The makeup tool 51 may be, for example, a makeup brush, lipstick, or eyelash curler. The makeup brush may be, for example, a foundation brush, an eyeshadow brush, etc. The smart mirror 50 may generate a pseudo image showing the user 17 with pseudo makeup applied based on the position, orientation, movement, etc. of the makeup tool 51, and allow the user 17 to view the pseudo image as a real image or a virtual image. In this case, the user 17 can check their own face with makeup applied before actually applying the makeup, thereby improving convenience for the user 17.

[0102] The smart mirror 50 may acquire information about hairstyle from the server 53. Based on the image of the user 17 captured by the imaging unit 16 and the information about the hairstyle acquired from the server 53, the smart mirror 50 may generate a pseudo image in which the hairstyle of the user 17 has been changed to a hairstyle specified by the acquired information. As shown in FIG. 9 , the smart mirror 50 may allow the user 17 to view the generated pseudo image as a real image R or a virtual image V. In this case, the user 17 can check their face or head with the changed hairstyle before actually changing their hairstyle, thereby improving convenience for the user 17.

[0103] The smart mirror 50 may acquire information about the cosmetic product from the server 53 based on the name (product name) of the cosmetic product input by the user 17. The user 17 does not need to input the name of the cosmetic product. The name of the cosmetic product may be included in text data encoded in a QR code (registered trademark) and read by the imaging unit 16. The name of the cosmetic product may also be provided through a website. The smart mirror 50 may generate a pseudo image of the user 17 wearing makeup using the cosmetic product based on the acquired cosmetic product information, and allow the user 17 to view the generated pseudo image as a real image R or a virtual image V. In this case, the user 17 can check their own face with makeup using the cosmetic product before purchasing the cosmetic product, thereby improving convenience for the user 17.

[0104] The smart mirror 50 may be powered by power supplied from an outlet or by power supplied from an internal battery, which may be charged by power supplied from an outlet.

[0105] The smart mirror 50 may be used as a normal mirror when the display panel 2 and the illuminator 7 are OFF (non-operating state). The user 17 can see his or her own mirror image reflected in the third semi-transparent mirror 10 or the fifth semi-transparent mirror 14 of the display device 1, or the second semi-transparent mirror 21 or the first semi-transparent mirror 20 of the display device 1A.

[0106] The smart mirror 50 can assist the user 17 with makeup and hair styling, thereby improving convenience for the user 17.

[0107] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be variously changed, modified, or modified within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. For example, the functions contained in each component, etc. can be rearranged so as not to cause logical contradictions, and multiple components, etc. can be combined into one or divided. In other words, it should be noted that those skilled in the art can easily make various modifications or alterations based on the present disclosure. It should also be noted that these modifications, alterations, or alterations are included within the scope of the present disclosure.

[0108] According to the present disclosure, an image displayed on a display panel can be projected as at least one of a real image and a virtual image at a position different from the display panel, making it easier for a user to view the image.

[0109] The display device of the present disclosure can be implemented in the following aspects (1) to (11).

[0110] (1) A display device comprising: a display panel that displays an image; a first optical system that projects the image displayed on the display panel as a real image; a second optical system that projects the image displayed on the display panel as a virtual image; and a control unit, wherein the control unit controls the display of the image so as to project at least one of the real image and the virtual image.

[0111] (2) The display device described in (1) above includes a drive unit that controls the relative position between the display panel and the focal point on the display panel side in the first optical system, and the relative position between the display panel and the focal point on the display panel side in the second optical system, and the control unit controls the drive unit so that the display panel is located farther away from the focal point on the display panel side in the first optical system and closer to the focal point on the display panel side in the second optical system.

[0112] (3) The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror to the first retardation plate; a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction; and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror across the first semi-transparent mirror, the first retardation plate, and the second retardation plate, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction. the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction; and a fifth semi-transparent mirror located on the opposite side of the first semi-transparent mirror, the first retardation plate, and the second retardation plate from the fourth semi-transparent mirror, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction.

[0113] (4) The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror to the first retardation plate; a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction; and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror across the first semi-transparent mirror, the first retardation plate, and the second retardation plate, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction. the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction; and a fifth semi-transparent mirror located on the opposite side of the first semi-transparent mirror, the first retardation plate, and the second retardation plate from the fourth semi-transparent mirror, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction.

[0114] (5) The display device described in (4) above, wherein the control unit controls the drive unit so that: the distance between the first semi-transparent mirror and the second semi-transparent mirror is approximately equal to the distance between the first semi-transparent mirror and the third semi-transparent mirror; the distance between the first semi-transparent mirror and the fourth semi-transparent mirror is approximately equal to the distance between the first semi-transparent mirror and the fifth semi-transparent mirror; the distance between the display panel and the third semi-transparent mirror is greater than the focal length on the display panel side in the first optical system; and the distance between the display panel and the fifth semi-transparent mirror is smaller than the focal length on the display panel side in the second optical system.

[0115] (6) The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, and the second retardation plate. The display device described in (1) above, further comprising: a third semi-transparent mirror having a concave reflective surface facing the first semi-transparent mirror via the first retardation film or the second retardation film, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction.

[0116] (7) The display device described in (6) above, wherein the second semi-transparent mirror is located at a distance from the second retardation plate in the emission direction, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate; and the third semi-transparent mirror is located between the display panel and the first retardation plate, and the concave reflective surface of the third semi-transparent mirror faces the first semi-transparent mirror via the first retardation plate.

[0117] (8) The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflective surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, and a concave reflective surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate. The display device according to (2) above, further comprising: a third semi-transparent mirror having a reflective surface, transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction.

[0118] (9) The display device described in (8) above, wherein the control unit controls the drive unit so that the distance between the display panel and the second semi-transparent mirror is greater than the focal length on the display panel side in the first optical system, and the sum of twice the distance between the first semi-transparent mirror and the third semi-transparent mirror and the distance between the display panel and the third semi-transparent mirror is less than the focal length on the display panel side in the second optical system.

[0119] (10) A display device according to any one of (1) to (9) above, comprising an imaging unit that images the user, and the control unit controls the display panel to display an image including an image of the user generated based on imaging data output from the imaging unit.

[0120] (11) A display device described in any of (1) to (10) above, wherein the control unit controls the display panel to display a first image projected as the real image and a second image projected as the virtual image, and to make the size of the first image different from the size of the second image.

[0121] REFERENCE SIGNS LIST 1, 1A Display device 2 Display panel 2a Display surface 3 First optical system 4 Second optical system 5 Drive unit 7 Illuminator 8 First semi-transparent mirror 8a Reflecting surface 8b Reflecting surface 9 Second semi-transparent mirror 9a Reflecting surface 10 Third semi-transparent mirror 10a Reflecting surface 11 First retardation plate 12 Second retardation plate 13 Fourth semi-transparent mirror 13a Reflecting surface 14 Fifth semi-transparent mirror 14a Reflecting surface 15 Control unit 16 Imaging unit 17 User 18 First optical system 19 Second optical system 20 First semi-transparent mirror 20a Reflecting surface 20b Reflecting surface 21 Second semi-transparent mirror 21a Reflecting surface 22 First retardation plate 23 Second retardation plate 24 Third semi-transparent mirror 24a Reflecting surface 50 Smart mirror 51 Makeup tools 52 Input interface 53 Server 54 Makeup Advisor

Claims

1. A display device comprising: a display panel that displays an image; a first optical system that projects the image displayed on the display panel as a real image; a second optical system that projects the image displayed on the display panel as a virtual image; and a control unit, wherein the control unit controls the display of the image so as to project at least one of the real image and the virtual image.

2. A display device as described in claim 1, comprising a drive unit that controls the relative position between the display panel and the focal point on the display panel side in the first optical system, and the relative position between the display panel and the focal point on the display panel side in the second optical system, wherein the control unit controls the drive unit so that the display panel is located farther away from the focal point on the display panel side in the first optical system and closer to the focal point on the display panel side in the second optical system.

3. The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction; and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror between the first semi-transparent mirror, the first retardation plate, and the second retardation plate, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction, 2. The display device according to claim 1, wherein the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, a fourth semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction, and a fifth semi-transparent mirror located on the opposite side of the first semi-transparent mirror, the first retardation plate, and the second retardation plate from the fourth semi-transparent mirror, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction.

4. The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; a second semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction; and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror between the first semi-transparent mirror, the first retardation plate, and the second retardation plate, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction, 3. The display device according to claim 2, wherein the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, a fourth semi-transparent mirror located between the display panel and the first retardation plate, having a concave reflective surface facing the first retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction, and a fifth semi-transparent mirror located on the opposite side of the first semi-transparent mirror, the first retardation plate, and the second retardation plate from the fourth semi-transparent mirror, having a concave reflective surface facing the second retardation plate, and reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction.

5. The display device described in claim 4, wherein the control unit controls the drive unit so that: the distance between the first semi-transparent mirror and the second semi-transparent mirror is approximately equal to the distance between the first semi-transparent mirror and the third semi-transparent mirror; the distance between the first semi-transparent mirror and the fourth semi-transparent mirror is approximately equal to the distance between the first semi-transparent mirror and the fifth semi-transparent mirror; the distance between the display panel and the third semi-transparent mirror is greater than the focal length on the display panel side in the first optical system; and the distance between the display panel and the fifth semi-transparent mirror is smaller than the focal length on the display panel side in the second optical system.

6. The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, and 2. The display device according to claim 1, further comprising: a third semi-transparent mirror having a concave reflective surface facing the first semi-transparent mirror via the first retardation film or the second retardation film, the third semi-transparent mirror transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction.

7. The display device described in claim 6, wherein the second semi-transparent mirror is located at a distance from the second retardation plate in the emission direction, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate, and the third semi-transparent mirror is located between the display panel and the first retardation plate, and the concave reflective surface of the third semi-transparent mirror faces the first semi-transparent mirror via the first retardation plate.

8. The display panel emits linearly polarized image light having a polarization axis in a first direction, and the first optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, and transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction, and the first retardation plate and the second retardation plate are quarter-wave plates, and the second optical system includes: the first semi-transparent mirror, the first retardation plate, the second retardation plate, and 3. The display device according to claim 2, further comprising: a third semi-transparent mirror having a concave reflective surface facing the first semi-transparent mirror via the first retardation film or the second retardation film, the third semi-transparent mirror transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in the second direction.

9. The display device described in claim 8, wherein the control unit controls the drive unit so that the distance between the display panel and the second semi-transparent mirror is greater than the focal length on the display panel side in the first optical system, and the sum of twice the distance between the first semi-transparent mirror and the third semi-transparent mirror and the distance between the display panel and the third semi-transparent mirror is less than the focal length on the display panel side in the second optical system.

10. A display device according to any one of claims 1 to 9, further comprising an imaging unit that images the user, and wherein the control unit controls the display panel to display an image including an image of the user, the image being generated based on imaging data output from the imaging unit.

11. A display device according to any one of claims 1 to 10, wherein the control unit controls the display panel to display a first image projected as the real image and a second image projected as the virtual image, and to make the size of the first image and the size of the second image different.

Images