Aerial image display system and input system

Abstract

The present invention provides a thin aerial image display system capable of displaying an aerial image, and an input device capable of a touch operation on an image displayed in the air without touching a screen. The aerial image display system includes a reflective polarizer and a half mirror, and the half mirror is any of semireflective and semitransmissive concave mirror, Fresnel mirror, and retroreflective member.

Description

[Technical Field]

[0001] The present invention relates to an aerial image display system and an input system using this aerial image display system. [Background technology]

[0002] In recent years, aerial image display devices that display images in the air without the need for a screen have been proposed, and they are expected to be used as promotional displays with a highly eye-catching effect, and as input devices that allow users to touch and operate images displayed in the air without having to touch a screen.

[0003] An input device that allows users to touch images displayed in the air is hygienic because it eliminates the need to touch the screen. Therefore, it is expected to be used as an input device that is touched by an unspecified number of people, in medical settings, etc. Furthermore, because aerial images are difficult to see from any direction other than the front, it is expected to be effective in preventing people from peering into an automated teller machine (ATM) when entering a PIN number, for example.

[0004] For example, Patent Document 1 describes an optical imaging device for forming a real image of an object to be projected, which includes a polarizer that transmits P-polarized light with a polarization axis parallel to a reference direction and reflects S-polarized light with a polarization axis perpendicular to the reference direction, a first phase difference element that converts S-polarized light into circularly polarized light or elliptically polarized light, a mirror that reflects light that has passed through the first phase difference element, a second phase difference element that converts P-polarized light that has been reflected by the mirror, passed through the first phase difference element, and transmitted through the polarizer into circularly polarized light or elliptically polarized light, and a retroreflector that retroreflects light that has passed through the second phase difference element.

[0005] The optical imaging device described in Patent Document 1 converts light from the object to be projected (light projection means) into S-polarized light and makes it incident on a polarizer, reflects the S-polarized light reflected by the polarizer using a mirror, converts the light into P-polarized light, transmits it through the polarizer, reflects it using a retroreflector, converts the light into S-polarized light, and reflects it to the visible side using the polarizer, thereby displaying an image of the object to be projected in the air. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-092135 Summary of the Invention [Problem to be solved by the invention]

[0007] In such an optical imaging device, the polarizer needs to be arranged non-parallel to the mirror and the retroreflector (see, for example, FIG. 2 of Patent Document 1), which poses a problem of increasing the size of the device.

[0008] An object of the present invention is to provide a thin aerial image display system capable of displaying aerial images, and an input device that allows touch operation of an image displayed in the air without touching the screen. [Means for solving the problem]

[0009] In order to solve this problem, the present invention has the following configuration. [1] A reflective polarizer; a half mirror; An aerial image display system, wherein the half mirror is one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member. [2] Further, the device is provided with an image display device, The aerial image display system according to [1], wherein the reflective polarizer and the half mirror are arranged on the viewing side of the image display device. [3] The aerial image display system according to [2], further comprising a polarization separation element having the function of separating incident light into polarized light beams perpendicular to each other. [4] The aerial image display system described in [3], wherein the polarization separation element has either an active retardation layer that can switch the direction of the slow axis or the magnitude of retardation, a patterned retardation layer having a plurality of two types of regions that differ in at least one of the direction of the slow axis and the magnitude of retardation, an active polarizer that can switch the direction of the transmission axis or the absorption axis, or a patterned polarizer that has a plurality of two types of regions that differ in the direction of the transmission axis or the absorption axis. [5] The reflective polarizer is a reflective linear polarizer, Further, the optical element has a retardation plate, The aerial image display system according to [3] or [4], wherein an image display device, a polarization separation element, a half mirror, a retardation plate, and a reflective polarizer are arranged in this order. [6] The reflective polarizer is a reflective circular polarizer; The aerial image display system according to [3] or [4], wherein an image display device, a polarization separation element, a half mirror, and a reflective polarizer are arranged in this order. [7] The reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [3] or [4], wherein an image display device, an absorptive linear polarizer, a retardation plate, a half mirror, a polarization separation element, and a reflective polarizer are arranged in this order. [8] The reflective polarizer is a reflective linear polarizer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [3] or [4], wherein an image display device, an absorptive linear polarizer, a reflective polarizer, a retardation plate, a half mirror, and a polarization separation element are arranged in this order. [9] The reflective polarizer is a reflective circular polarizer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [3] or [4], wherein an image display device, an absorptive linear polarizer, a retardation plate, a reflective polarizer, a half mirror, and a polarization separation element are arranged in this order.

[10] The reflective polarizer is a reflective linear polarizer, Further, the optical element has an absorptive linear polarizer, The aerial image display system according to [3] or [4], wherein an image display device, an absorptive linear polarizer, a reflective polarizer, a polarization separation element, and a half mirror are arranged in this order.

[11] The reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and two retardation plates, The aerial image display system according to [2], wherein an image display device, an absorptive linear polarizer, a retardation plate, a half mirror, a retardation plate, and a reflective polarizer are arranged in this order.

[12] The reflective polarizer is a reflective circular polarizer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [2], wherein an image display device, an absorptive linear polarizer, a retardation plate, a half mirror, and a reflective polarizer are arranged in this order.

[13] The reflective polarizer is a reflective linear polarizer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [2], wherein an image display device, an absorptive linear polarizer, a reflective polarizer, a retardation plate, and a half mirror are arranged in this order.

[14] The reflective polarizer is a reflective circular polarizer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, The aerial image display system according to [2], wherein an image display device, an absorptive linear polarizer, a retardation plate, a reflective polarizer, and a half mirror are arranged in this order.

[15] The aerial image display system according to any one of [5], [7] and

[11] , further comprising an absorptive linear polarizer on the viewing side of the reflective polarizer.

[16] The aerial image display system according to any one of [6],

[10] , and

[12] to

[14] , further comprising an absorptive circular polarizer on the viewing side.

[17] A half mirror has a support and a reflecting surface disposed on a surface of the support, A coating layer having the same refractive index as the support is disposed on the reflective surface; The aerial image display system according to any one of [1] to

[16] , wherein the surface of the support opposite to the reflecting surface and the surface of the covering layer opposite to the reflecting surface are flat surfaces parallel to each other.

[18] An aerial image display system according to any one of [1] to

[17] ; An input system having a non-contact touch sensor. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thin aerial image display system capable of displaying aerial images, and an input device that allows touch operation of an image displayed in the air without touching the screen. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram conceptually illustrating an example of an aerial image display system according to the present invention. [Figure 2] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 3] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 4] FIG. 1 is a diagram illustrating an example of a non-floating image displayed by the aerial image display system of the present invention. [Figure 5] 1 is a diagram illustrating an example of an aerial image displayed by the aerial image display system of the present invention. [Figure 6] 1A and 1B are diagrams conceptually illustrating examples of superimposed images displayed by the aerial image display system of the present invention. [Figure 7] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 8] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 9] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 10] FIG. 10 is a diagram conceptually illustrating another example of the aerial image display system of the present invention. [Figure 11]FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 12] FIG. 12 is a diagram showing a state in which the aerial image display system shown in FIG. 11 displays a non-floating image. [Figure 13] FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 14] FIG. 14 is a diagram showing a state in which the aerial image display system shown in FIG. 13 displays a non-floating image. [Figure 15] FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 16] FIG. 16 is a diagram showing a state in which the aerial image display system shown in FIG. 15 displays a non-floating image. [Figure 17] FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 18] FIG. 18 is a diagram showing a state in which the aerial image display system shown in FIG. 17 displays a non-floating image. [Figure 19] FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 20] FIG. 20 is a diagram showing a state in which the aerial image display system shown in FIG. 19 displays a non-floating image. [Figure 21] FIG. 10 is a conceptual diagram illustrating another example of the aerial image display system of the present invention, showing a state in which an aerial image is displayed. [Figure 22] FIG. 22 is a diagram showing a state in which the aerial image display system shown in FIG. 21 displays a non-floating image. [Figure 23] FIG. 1 is a diagram conceptually illustrating an input system having an aerial image display system of the present invention. [Figure 24] FIG. 1 is a conceptual diagram illustrating an example of a half mirror. [Figure 25] FIG. 10 is a diagram conceptually illustrating another example of a half mirror. [Figure 26]FIG. 1 is a plan view conceptually illustrating an example of a corner cube array. [Figure 27] FIG. 1 is a perspective view conceptually illustrating an example of a corner cube array. [Figure 28] FIG. 10 is a diagram conceptually illustrating another example of a half mirror. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, "perpendicular" and "parallel" angles refer to a range of ±10° of the exact angle, and "same" and "different" angles can be determined based on whether the difference is less than 5°.

[0013] In this specification, the term "slow axis" refers to the direction in which the refractive index is maximum in the plane. Visible light is electromagnetic radiation with wavelengths visible to the human eye, and refers to light in the wavelength range of 380 to 780 nm.

[0014] <Aerial image display system> The aerial image display system of the present invention comprises: a reflective polarizer; a half mirror; In the aerial image display system, the half mirror is one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member.

[0015] FIG. 1 is a conceptual diagram of an aerial image display system according to the present invention.

[0016] The aerial image display system 10a shown in FIG. 1 includes a half mirror 12 and a reflective polarizer 14.

[0017] The half mirror 12 is a semi-reflective, semi-transmissive half mirror that reflects part of the incident light and transmits the rest. In the present invention, the half mirror 12 is any of a concave mirror, a Fresnel mirror, and a retroreflective member. This half mirror 12 has the function of forming an image in the air using the reflected light.

[0018] The reflective polarizer 14 transmits light of one polarization state among incident light and reflects light polarized orthogonal to the polarization state. Here, the orthogonal polarizations are, for example, polarizations located on the back side of the Poincaré sphere, such as the north and south poles of the Poincaré sphere. Specifically, the orthogonal polarizations are, for example, right-handed and left-handed circularly polarized light in the case of circularly polarized light, and orthogonal linear polarizations in the case of linearly polarized light. The reflective polarizer 14 may be a reflective linear polarizer or a reflective circular polarizer.

[0019] The operation of such aerial image display system 10a will now be described. In the example shown in FIG. 1, the aerial image display system 10a is placed between an object O and a user U, with the half mirror 12 side facing the object O. When light is irradiated onto object O, the light is reflected from the surface of object O. At that time, as shown in FIG. 1, the light is emitted from each point on object O so as to spread in various directions. A portion of the reflected light is transmitted through half mirror 12. The light that has passed through half mirror 12 is incident on reflective polarizer 14. If reflective polarizer 14 is a reflective circular polarizer, the circularly polarized component of the incident light that is reflected by reflective polarizer 14 is reflected by reflective polarizer 14. Because reflection by reflective polarizer 14 is specular reflection, the light is reflected so as to spread further.

[0020] The circularly polarized light reflected by the reflective polarizer 14 is incident on the half mirror 12 again. A portion of the incident light is reflected by the half mirror 12. At this time, for example, if the half mirror 12 is a retroreflective member, the traveling direction of the light reflected by the half mirror 12 is a direction parallel to and opposite to the direction of travel from the reflective polarizer 14 to the half mirror 12. Therefore, the light reflected by the half mirror 12 is condensed. Furthermore, the circularly polarized light reflected by the half mirror 12 is converted into circularly polarized light with the opposite rotation direction. Therefore, the circularly polarized light reflected by the half mirror 12 passes through the reflective polarizer 14 and is condensed, forming an image in the air.

[0021] In this way, light from object O, which is located further back than the aerial image display system 10a as seen from the user U, is imaged by the aerial image display system 10a in the space in front of the aerial image display system 10a, thereby allowing an aerial image V1 of object O to be displayed in the space in front of the aerial image display system 10a. Note that the aerial image V1 is a real image formed in the air.

[0022] In the example shown in Figure 1, the aerial image display system 10a is configured so that the half mirror 12 is arranged on the object O side and the reflective polarizer 14 is arranged on the user U side, but this is not limited to this, and the configuration may also be such that the reflective polarizer 14 is arranged on the object O side and the half mirror 12 is arranged on the user U side. In this configuration, the half mirror 12 reflects the polarized component of the light from the object O that is transmitted by the reflective polarizer 14. At that time, the polarization state is converted into orthogonal polarization, and the polarized light reflected by the half mirror 12 is then reflected by the reflective polarizer 14. A portion of the light reflected by the reflective polarizer 14 is transmitted through the half mirror 12. In addition, since the light reflected by the half mirror 12 is condensed, the light can be focused in the space in front of the aerial image display system 10a, and an aerial image V1 of the object O can be displayed.

[0023] In the example shown in FIG. 1, the aerial image display system 10a displays an aerial image V1 of an object O placed behind the aerial image display system 10a, but the present invention is not limited to this.

[0024] FIG. 2 shows another example of the aerial image display system of the present invention. The aerial image display system 10b shown in FIG. 2 includes an image display device 16, a half mirror 12, and a reflective polarizer 14 in this order.

[0025] The image display device 16 is a known image display device (display). Examples of image display devices include a liquid crystal display device, an organic electroluminescence display device, an LED (Light Emitting Diode) display device, and a micro LED display device. In addition, if the aerial image may be a still image, the image display device may be a photograph with a backlight, a printed matter, or the like. In the following description, the organic electroluminescence display device is also referred to as an OLED. OLED is an abbreviation for "Organic Light Emitting Diode."

[0026] The half mirror 12 and the reflective polarizer 14 are disposed on the viewing side of the image display device 16. The half mirror 12 and the reflective polarizer 14 are as described above.

[0027] The operation of such aerial image display system 10b will now be described. Image display device 16 emits light that forms an image. At this time, as shown in FIG. 2, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by image display device 16 is incident on half mirror 12, and a portion of the light is transmitted through half mirror 12. The light that has transmitted through half mirror 12 is incident on reflective polarizer 14. When reflective polarizer 14 is a reflective circular polarizer, the circularly polarized component of the incident light that is reflected by reflective polarizer 14 is reflected by reflective polarizer 14. Because reflection by reflective polarizer 14 is specular reflection, the light is reflected so as to spread further.

[0028] The circularly polarized light reflected by the reflective polarizer 14 is incident on the half mirror 12 again. A portion of the incident light is reflected by the half mirror 12. At this time, for example, if the half mirror 12 is a retroreflective member, the traveling direction of the light reflected by the half mirror 12 is a direction parallel to and opposite to the direction of travel from the reflective polarizer 14 to the half mirror 12. Therefore, the light reflected by the half mirror 12 is condensed. Furthermore, the circularly polarized light reflected by the half mirror 12 is converted into circularly polarized light with the opposite rotation direction. Therefore, the circularly polarized light reflected by the half mirror 12 passes through the reflective polarizer 14 and is condensed, forming an image in the air.

[0029] In this way, in the aerial image display system 10b, the light irradiated from the image display device 16 forms an image in the space on the reflective polarizer 14 side (downstream side) of the aerial image display system 10b, thereby enabling an aerial image V1 of the image displayed by the image display device 16 to be displayed in the space downstream of the aerial image display system 10b. In the present invention, the term "downstream" refers to the downstream in the optical path of the image displayed (illuminated) by the image display device 16.

[0030] 2, of the light that has passed through half mirror 12 and entered reflective polarizer 14, the circularly polarized component that is not reflected by reflective polarizer 14 passes through reflective polarizer 14 and is irradiated from aerial image display system 10b. The image formed by this light is visually recognized by user U as a real image that does not float in the air (hereinafter referred to as a "non-floating image").

[0031] That is, in the example shown in FIG. 2, the same image displayed by the image display device 16 is displayed as a non-floating image and an aerial image.

[0032] In the example shown in Figure 2, aerial image display system 10b is configured so that half mirror 12 and reflective polarizer 14 are arranged in this order from the image display device 16 side, but this is not limited to this, and the configuration may also be so that reflective polarizer 14 and half mirror 12 are arranged in this order from the image display device 16 side. In this configuration, half mirror 12 reflects the polarized component of the light from image display device 16 that is transmitted by reflective polarizer 14. At that time, the polarization state is converted into orthogonal polarization, and the polarized light reflected by half mirror 12 is then reflected by reflective polarizer 14. A portion of the light reflected by reflective polarizer 14 is transmitted through half mirror 12. In addition, since the light reflected by half mirror 12 is condensed, the light can be focused in the space downstream of aerial image display system 10b, and an aerial image V1 of the image displayed by image display device 16 can be displayed.

[0033] Here, the aerial image display system of the present invention may further include a polarization separation element having a function of separating incident light into polarized light beams that are orthogonal to each other. FIG. 3 is a diagram conceptually showing another example of the aerial image display system of the present invention. An aerial image display system 10c shown in FIG. 3 includes an image display device 16, a half mirror 12, a reflective polarizer 14, and a polarization separation element 18, in this order.

[0034] The polarization separation element 18 is an element that separates at least a portion of the incident light into polarized light that is orthogonal to each other. Here, the polarized light that is orthogonal to each other refers to polarized light that is located on the opposite side of the Poincaré sphere, such as the north and south poles of the Poincaré sphere. Specifically, polarized light with opposite properties refers to, for example, right-handed and left-handed circularly polarized light in the case of circular polarization, and to linearly polarized light that is orthogonal to each other in the case of linear polarization.

[0035] The half mirror 12, the reflective polarizer 14, and the polarization separation element 18 are disposed on the viewing side of the image display device 16. The half mirror 12 and the reflective polarizer 14 are as described above.

[0036] Such an aerial image display system 10c displays two types of images that are superimposed to form a multiplexed image. Of these two types of images, image R is not reflected by half mirror 12 or reflective polarizer 14, but passes through half mirror 12, reflective polarizer 14, and polarization separation element 18, and is observed by user U (see the dashed arrow in FIG. 3). In other words, image R is an image displayed by image display device 16 that is directly observed by user U. Hereinafter, for convenience, this image R will also be referred to as non-floating image R.

[0037] The other image V1 is image V1 that passes through the half mirror 12, is selectively reflected by the reflective polarizer 14, is reflected by the half mirror 12, passes through the reflective polarizer 14, and is observed by the user U. That is, image V1 has an optical path that travels back and forth between the half mirror 12 and the reflective polarizer 14 (see the solid arrows in FIG. 3). Hereinafter, for convenience, this image V1 will also be referred to as aerial image V1. The optical path of the aerial image V1 in this aerial image display system 10c is the same as the optical path of the aerial image V1 in the aerial image display system 10b shown in FIG. 2. As will be described later, the non-floating image R and the aerial image V1 have their optical paths separated by the polarization separation element 18 separating the polarized light.

[0038] 4 to 6 show examples of images displayed by the aerial image display system 10c. FIG. 4 shows an example of a non-floating image R displayed by the aerial image display system 10c. FIG. 5 shows an example of an aerial image V1 displayed by the aerial image display system 10c. FIG. 6 shows an example of a superimposed image V2 displayed by the aerial image display system 10c. As shown in FIG. 6, the aerial image display system 10c displays the non-floating image R and the aerial image V1 in a superimposed manner. When the user U observes such a superimposed image V2, the aerial image V1 appears to be positioned in front of the superimposed non-floating image R and aerial image V1. In other words, in the superimposed image V2 observed by the user U, the aerial image V1 appears to be floating above the non-floating image R.

[0039] As an example, such an aerial image display system of the present invention is used in a car navigation system, and a map image is displayed as a non-floating image R, and additional information such as location information, weather, and arrival time is displayed as an aerial image V1, as conceptually shown in Figures 4 to 6. In this case, a user U visually recognizes the additional information as floating in front of the map image. As a result, the user U can distinguish at a glance between the map image and the additional information in the superimposed image he or she is observing, and can accurately and quickly find the information he or she needs.

[0040] Here, in the aerial image display system 10c, the image display device 16 alternately displays the image that will become the non-floating image R and the image that will become the aerial image V1 in a time-division manner. Alternatively, the image display device 16 displays the image that will become the non-floating image R and the image that will become the aerial image V1 in an alternate arrangement by dividing the space into, for example, stripes. When the image display device 16 performs time-division display, the polarization separation element 18 performs polarization conversion or absorption on the incident light alternately over time, thereby separating the incident light into polarized lights that are orthogonal to each other. When the image display device 16 performs space-division display, the polarization separation element 18 performs polarization conversion or absorption on the incident light alternately over space, for example, in a striped pattern, thereby separating the incident light into polarized lights that are orthogonal to each other.

[0041] In the case of time-division display in aerial image display system 10c, when non-floating image R is displayed, polarization separation element 18 operates so that polarized light that has passed through half mirror 12 and reflective polarizer 14 without being reflected by them is ultimately emitted to the viewing side, and polarized light that has been reflected between half mirror 12 and reflective polarizer 14 and made one round trip is ultimately absorbed or reflected and does not exit to the viewing side. On the other hand, when aerial image V1 is displayed, polarization separation element 18 operates so that polarized light that has been reflected between half mirror 12 and reflective polarizer 14 and made one round trip is emitted to the viewing side, and polarized light that has been transmitted through half mirror 12 and reflective polarizer 14 without being reflected by them is absorbed or reflected and does not exit to the viewing side.

[0042] Furthermore, when aerial image display system 10c performs space-division display, at the position where non-floating image R is displayed, polarization separation element 18 operates so that polarized light that has transmitted through half mirror 12 and reflective polarizer 14 without being reflected by them finally exits toward the viewing side, and polarized light that has reflected between half mirror 12 and reflective polarizer 14 and made one round trip is finally absorbed or reflected and does not exit toward the viewing side. On the other hand, at the position where aerial image V1 is displayed, polarization separation element 18 operates so that polarized light that has reflected between half mirror 12 and reflective polarizer 14 and made one round trip exits toward the viewing side, and polarized light that has transmitted through half mirror 12 and reflective polarizer 14 without being reflected by them is absorbed or reflected and does not exit toward the viewing side.

[0043] As a result, the aerial image display system 10c can prevent an image that should be displayed as a non-floating image R from being displayed as an aerial image, and can also prevent an image that should be displayed as an aerial image V1 from being displayed as a non-floating image, and can display superimposed images that allow an image that will become a non-floating image R to be properly viewed as a non-floating image R, and an image that will become an aerial image V1 to be properly viewed as aerial image V1.

[0044] 3, the polarization separation element 18 is arranged closer to the viewer than the reflective polarizer 14, but this is not limiting. The polarization separation element 18 may be arranged between the image display device 16 and the half mirror 12. Alternatively, the polarization separation element 18 may be arranged between the half mirror 12 and the reflective polarizer 14.

[0045] In addition, in the example shown in Figure 3, the aerial image display system 10c is configured so that the half mirror 12 and the reflective polarizer 14 are arranged in this order from the image display device 16 side, but this is not limited to this, and the aerial image display system 10c may also be configured so that the reflective polarizer 14 and the half mirror 12 are arranged in this order from the image display device 16 side.

[0046] A specific configuration of the aerial image display system of the present invention will be described in more detail below. First, an aerial image display system for displaying an aerial image as shown in FIG. 2 will be described.

[0047] FIG. 7 is a diagram conceptually showing another example of the aerial image display system of the present invention. 7 includes an image display device 16, an absorptive linear polarizer 20, a retardation layer 22, a half mirror 12, a retardation layer 24, and a reflective linear polarizer 14a. In a preferred embodiment, the aerial image display system 10d also includes an absorptive linear polarizer 26 located closer to the viewing side than the reflective linear polarizer 14a. That is, the aerial image display system 10d has, as the reflective polarizer 14, a reflective linear polarizer 14a that transmits linearly polarized light oscillating in a certain direction and reflects linearly polarized light in a direction perpendicular to this direction.

[0048] The absorptive linear polarizer 20 and the absorptive linear polarizer 26 are known absorptive linear polarizers. The retardation layers 22 and 24 are known retardation layers. As will be described below, the retardation layers convert linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light, and are therefore essentially quarter-wave plates.

[0049] The operation of such aerial image display system 10d will now be described. The image display device 16 emits light that will become an image (aerial image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up-and-down direction in the figure. Next, this linearly polarized light passes through the retardation layer 22 and is converted into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up-and-down direction into right-handed circularly polarized light.

[0050] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 22 and is converted into linearly polarized light in a direction perpendicular to the up-down direction (direction perpendicular to the paper surface). This linearly polarized light is not transmitted through the absorbing linear polarizer 20, and is therefore absorbed by the absorbing linear polarizer 20. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and then passes through the retardation layer 24. At that time, it is converted into linearly polarized light by the retardation layer 24. In the illustrated example, as an example, the retardation layer 24 converts the right-handed circularly polarized light into linearly polarized light in the up and down direction.

[0051] The linearly polarized light that has passed through the retardation layer 24 is incident on the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a reflects vertically linearly polarized light, and therefore the linearly polarized light that has entered the reflective linear polarizer 14a is reflected and enters the retardation layer 24. The retardation layer 24 converts the incident vertically linearly polarized light into right-handed circularly polarized light.

[0052] This right-handed circularly polarized light is incident on the half mirror 12 and is partially reflected. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. Furthermore, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensing manner. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into linearly polarized light by the retardation layer 22, transmitted through the absorptive linear polarizer 20, and absorbed by the surface of the image display device 16, etc.

[0053] The left-handed circularly polarized light reflected by the half mirror 12 enters the retardation layer 24 and is converted into linearly polarized light in a direction perpendicular to the up-down direction (a direction perpendicular to the paper surface; for the sake of explanation, this is shown as a left-right arrow in the figure; in the following explanation, it is also referred to as left-right linearly polarized light). This linearly polarized light is linearly polarized in a direction perpendicular to the linearly polarized light reflected by the reflective linear polarizer 14a, and therefore passes through the reflective linear polarizer 14a. The linearly polarized light that has passed through the reflective linear polarizer 14a is incident on the absorbing linear polarizer 26. The absorbing linear polarizer 26 passes linearly polarized light in the same direction as the linearly polarized light passed through the reflective linear polarizer 14a. Therefore, in the illustrated example, the absorbing linear polarizer 26 passes linearly polarized light in the left-right direction in the figure.

[0054] In this way, the aerial image display system 10d irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0055] Furthermore, in a preferred embodiment, aerial image display system 10d includes an absorbing linear polarizer 26 on the viewing side of reflective linear polarizer 14a. The inclusion of absorbing linear polarizer 26 allows stray light, such as vertically linearly polarized light components that have not been completely reflected by reflective linear polarizer 14a, to be absorbed by absorbing linear polarizer 26, thereby more reliably preventing unwanted images from being perceived due to stray light. Furthermore, glare caused by external light being reflected on the surface of aerial image display system 10d can be prevented.

[0056] In a preferred embodiment of the aerial image display system 10d, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 26 are perpendicular to each other. The transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 26 are parallel to each other. Furthermore, the slow axis of the retardation layer 22 and the slow axis of the retardation layer 24 are perpendicular to each other. The above-described configuration is preferable because it can further reduce stray light, such as vertically linearly polarized light components that have not been reflected by the reflective linear polarizer 14 a. However, the configuration is not limited to the above, and there may be an embodiment in which, for example, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 26 are parallel to each other.

[0057] Furthermore, in the aerial image display system 10d, it is preferable that the magnitude of the retardation of the retardation layer 22 and the magnitude of the retardation of the retardation layer 24 match. It is also preferable that the wavelength dispersion of the retardation layer 22 and the wavelength dispersion of the retardation layer 24 match, and it is more preferable that both have reverse dispersion. Here, reverse dispersion means that as the wavelength increases, the value of the retardation at that wavelength increases. The above-described configuration is preferable because it can further reduce stray light, such as vertically linearly polarized light components that have not been reflected by the reflective linear polarizer 14a.

[0058] Furthermore, in the aerial image display system 10d, it is preferable to bond the components together so that no air gaps exist between them. This is because the presence of air gaps can cause unwanted reflections at the air interfaces between the components or reflection of polarized light that should not be reflected in the reflective polarizer, resulting in stray light. For example, in the aerial image display system 10d, right-handed circularly polarized light that is incident on the half mirror 12 for the second time, passes through the half mirror 12, and travels toward the image display device 16 is converted to left-handed circularly polarized light when reflected by the surface of the retardation layer 22. The light then passes through the half mirror 12, the reflective linear polarizer 14a, and the absorptive linear polarizer 26, resulting in an unwanted image that is visually recognized by the user U. For the same reason, when an air layer exists between components in aerial image display system 10d, it is preferable to apply an anti-reflection treatment to the air-side surfaces of the components. Various known methods for anti-reflection treatment can be used, such as applying an AR film in which a thin film having a specific refractive index and film thickness is laminated, or applying a moth-eye film. As described above, the reduction of reflection between each member is similarly achieved in each of the embodiments shown in FIG. 8 and subsequent figures.

[0059] FIG. 8 is a diagram conceptually showing another example of the aerial image display system of the present invention. An aerial image display system 10e shown in FIG. 8 includes an image display device 16, an absorptive linear polarizer 20, a retardation layer 22, a half mirror 12, and a reflective circular polarizer 14b. That is, the aerial image display system 10e has, as the reflective polarizer 14, a reflective circular polarizer 14b that transmits circularly polarized light in one rotation direction and reflects circularly polarized light in the other rotation direction.

[0060] In addition, as a preferred embodiment, the aerial image display system 10e includes an absorptive circular polarizer 32 located closer to the viewing side than the reflective circular polarizer 14b. In the illustrated example, the absorptive circular polarizer 32 includes a retardation layer 24 and an absorptive linear polarizer 26.

[0061] The operation of such aerial image display system 10e will be described. The image display device 16 emits light that will become an image (aerial image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up-and-down direction in the figure. Next, this linearly polarized light passes through the retardation layer 22 and is converted into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up-and-down direction into right-handed circularly polarized light.

[0062] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 22 and is converted into linearly polarized light in a direction perpendicular to the up-down direction (direction perpendicular to the paper surface). This linearly polarized light is not transmitted through the absorbing linear polarizer 20, and is therefore absorbed by the absorbing linear polarizer 20. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and enters the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b reflects right-handed circularly polarized light, so the right-handed circularly polarized light that entered the reflective circular polarizer 14b is reflected and enters the half mirror 12.

[0063] A portion of the light incident on the half mirror 12 is reflected. At that time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into linearly polarized light by the retardation layer 22, transmitted through the absorptive linear polarizer 20, and absorbed by the surface of the image display device 16, etc.

[0064] The left-handed circularly polarized light reflected by the half mirror 12 enters the reflective circular polarizer 14b. The reflective circular polarizer 14b reflects right-handed circularly polarized light, and therefore transmits left-handed circularly polarized light. The left-handed circularly polarized light that has passed through the reflective circular polarizer 14b enters the absorbing circular polarizer 32. The absorbing circular polarizer 32 transmits circularly polarized light with the same rotation direction as the circularly polarized light that the reflective circular polarizer 14b transmits, converting it into linearly polarized light. Therefore, in the illustrated example, the absorbing circular polarizer 32 transmits left-handed circularly polarized light. Specifically, the left-handed circularly polarized light that has passed through the reflective circular polarizer 14b enters the retardation layer 24. The retardation layer 24 converts the incident left-handed circularly polarized light into left-handed linearly polarized light. The linearly polarized light that has passed through the retardation layer 24 enters the absorbing linear polarizer 26. The absorbing linear polarizer 26 transmits left-handed linearly polarized light. As a result, the absorptive circular polarizer 32 transmits circularly polarized light having the same rotation direction as the circularly polarized light transmitted by the reflective circular polarizer 14b while converting it into linearly polarized light.

[0065] In this way, the aerial image display system 10e irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0066] Furthermore, in a preferred embodiment, aerial image display system 10e includes an absorptive circular polarizer 32 located closer to the viewing side than reflective circular polarizer 14b. The inclusion of absorptive circular polarizer 32 allows stray light, such as right-handed circularly polarized light components that are not fully reflected by reflective circular polarizer 14b, to be absorbed by absorptive circular polarizer 32, thereby more reliably preventing unwanted images from being perceived due to stray light. Furthermore, glare caused by external light being reflected on the surface of aerial image display system 10e can be prevented.

[0067] In addition, in the aerial image display system 10e, the retardation layer 22 preferably has reverse dispersion. When the retardation layer 22 has reverse dispersion, the light incident on the reflective circular polarizer 14b becomes more ideal circularly polarized light, which is preferable because stray light can be further reduced. For the same reason, it is preferable that the retardation layer 24 also has reverse dispersion.

[0068] FIG. 9 is a diagram conceptually showing another example of the aerial image display system of the present invention. 9 includes an image display device 16, an absorptive linear polarizer 20, a reflective linear polarizer 14a, a retardation layer 22, and a half mirror 12. In a preferred embodiment, the aerial image display system 10f also includes an absorptive circular polarizer 32 located closer to the viewing side than the half mirror 12. That is, the aerial image display system 10f has, as the reflective polarizer 14, a reflective linear polarizer 14a that transmits linearly polarized light oscillating in a certain direction and reflects linearly polarized light oscillating in a direction perpendicular to this direction.

[0069] The operation of such aerial image display system 10f will be described. The image display device 16 emits light that forms an image (aerial image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 20 transmits linearly polarized light in the vertical direction in the figure, for example. This linearly polarized light then enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a transmits linearly polarized light in the vertical direction, so the linearly polarized light that enters the reflective linear polarizer 14a is transmitted without being reflected and enters the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light into circularly polarized light. In the illustrated example, the retardation layer 22 converts the vertically linearly polarized light into right-handed circularly polarized light, for example.

[0070] This right-handed circularly polarized light is incident on the half mirror 12, and a portion of it is transmitted therethrough. The right-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the absorptive circular polarizer 32. In the illustrated example, the absorptive circular polarizer 32 absorbs right-handed circularly polarized light, and therefore the right-handed circularly polarized light that has entered the absorptive circular polarizer 32 is absorbed. Specifically, the absorptive circular polarizer 32 has a retardation layer 24 and an absorptive linear polarizer 26, and the right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 24. The absorptive linear polarizer 26 absorbs vertically linearly polarized light, and therefore the vertically linearly polarized light is absorbed by the absorptive linear polarizer 26.

[0071] On the other hand, the remaining right-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner.

[0072] The left-handed circularly polarized light reflected by the half mirror 12 enters the retardation layer 22 and is converted into left-handed linearly polarized light. This linearly polarized light enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a reflects left-handed linearly polarized light, so the linearly polarized light that enters the reflective linear polarizer 14a is reflected. The linearly polarized light reflected by the reflective linear polarizer 14a enters the retardation layer 22 and is converted into left-handed circularly polarized light, which then enters the half mirror 12.

[0073] A portion of the left-handed circularly polarized light incident on the half mirror 12 is reflected and converted into right-handed circularly polarized light, which then enters the retardation layer 22 and is converted into vertically linearly polarized light. This linearly polarized light passes through the reflective linear polarizer 14a and the absorptive linear polarizer 20, and is absorbed by the surface of the image display device 16, etc.

[0074] On the other hand, some of the left-handed circularly polarized light that is incident on the half mirror 12 is transmitted through the half mirror 12. The left-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the absorbing circular polarizer 32. The absorbing circular polarizer 32 absorbs right-handed circularly polarized light, and therefore transmits the left-handed circularly polarized light. In the illustrated example, the absorbing circular polarizer 32 has a retardation layer 24 and an absorbing linear polarizer 26, and the left-handed circularly polarized light that has transmitted through the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 24. The absorbing linear polarizer 26 absorbs light that is linearly polarized in the up-down direction, and therefore the left-handed linearly polarized light is transmitted through the absorbing linear polarizer 26.

[0075] In this way, the aerial image display system 10f irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0076] Furthermore, in a preferred embodiment, aerial image display system 10f has an absorptive circular polarizer 32 on the viewing side of half mirror 12. By including absorptive circular polarizer 32, stray light such as right-handed circularly polarized light components that are not reflected by half mirror 12 can be absorbed by absorptive circular polarizer 32, thereby more reliably preventing unwanted images caused by stray light from being viewed. Furthermore, external light can be prevented from being reflected on the surface of aerial image display system 10e, causing so-called glare.

[0077] In a preferred embodiment of the aerial image display system 10f, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 26 are perpendicular to each other. The transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 20 are parallel to each other. Furthermore, the slow axis of the retardation layer 22 and the slow axis of the retardation layer 24 are perpendicular to each other. The retardation layers 22 and 24 preferably have the same retardation. They also preferably have the same wavelength dispersion, and more preferably both have reverse dispersion. The above-described configuration is preferable because it can further reduce stray light such as the right-handed circularly polarized light component that is not reflected by the half mirror 12.

[0078] FIG. 10 is a diagram conceptually showing another example of the aerial image display system of the present invention. 10 includes an image display device 16, an absorptive linear polarizer 20, a retardation layer 22, a reflective circular polarizer 14b, and a half mirror 12. In a preferred embodiment, the aerial image display system 10g also includes an absorptive circular polarizer 32 located closer to the viewing side than the half mirror 12. That is, the aerial image display system 10g has, as the reflective polarizer 14, a reflective circular polarizer 14b that transmits circularly polarized light in one rotation direction and reflects circularly polarized light in the other rotation direction.

[0079] The operation of such aerial image display system 10g will now be described. The image display device 16 emits light that will become an image (aerial image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up-and-down direction in the figure. Next, this linearly polarized light is incident on the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up-and-down direction into right-handed circularly polarized light.

[0080] This right-handed circularly polarized light is incident on the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b transmits right-handed polarized light, and therefore the right-handed polarized light incident on the reflective circular polarizer 14b is transmitted without being reflected and is incident on the half mirror 12.

[0081] This right-handed circularly polarized light is incident on the half mirror 12, and a portion of it is transmitted therethrough. The right-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the absorptive circular polarizer 32. In the illustrated example, the absorptive circular polarizer 32 absorbs right-handed circularly polarized light, and therefore the right-handed circularly polarized light that has entered the absorptive circular polarizer 32 is absorbed. Specifically, the absorptive circular polarizer 32 has a retardation layer 24 and an absorptive linear polarizer 26, and the right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 24. The absorptive linear polarizer 26 absorbs vertically linearly polarized light, and therefore the vertically linearly polarized light is absorbed by the absorptive linear polarizer 26.

[0082] On the other hand, the remaining right-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner.

[0083] The left-handed circularly polarized light reflected by the half mirror 12 is incident on the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b transmits right-handed circularly polarized light, so the left-handed circularly polarized light incident on the reflective circular polarizer 14b is reflected. The left-handed circularly polarized light reflected by the reflective circular polarizer 14b is incident on the half mirror 12.

[0084] A portion of the left-handed circularly polarized light incident on the half mirror 12 is reflected and converted into right-handed circularly polarized light, which then passes through the reflective circular polarizer 14b, enters the retardation layer 22, and is converted into vertically linearly polarized light. This linearly polarized light passes through the absorptive linear polarizer 20 and is absorbed by the surface of the image display device 16, etc.

[0085] On the other hand, the remaining left-handed circularly polarized light that is incident on the half mirror 12 is transmitted through the half mirror 12. The left-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the absorptive circular polarizer 32. The absorptive circular polarizer 32 absorbs right-handed circularly polarized light, and therefore transmits the left-handed circularly polarized light. In the illustrated example, the absorptive circular polarizer 32 has a retardation layer 24 and an absorptive linear polarizer 26, and the left-handed circularly polarized light that has transmitted through the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 24. The absorptive linear polarizer 26 absorbs light that is linearly polarized in the up-down direction, and therefore the left-handed linearly polarized light is transmitted through the absorptive linear polarizer 26.

[0086] In this way, the aerial image display system 10g irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0087] Furthermore, in a preferred embodiment, aerial image display system 10g includes an absorptive circular polarizer 32 on the viewing side of half mirror 12. The inclusion of absorptive circular polarizer 32 allows stray light, such as right-handed circularly polarized light components, that is not reflected by half mirror 12 to be absorbed by absorptive circular polarizer 32, thereby more reliably preventing unwanted images caused by stray light from being viewed. Additionally, glare caused by external light being reflected on the surface of aerial image display system 10g can be prevented.

[0088] In addition, in the aerial image display system 10g, it is preferable that the retardation layer 22 has reverse dispersion. When the retardation layer 22 has reverse dispersion, the light incident on the reflective circular polarizer 14b becomes more ideal circularly polarized light, which is preferable because it is possible to further reduce stray light. For the same reason, it is preferable that the retardation layer 24 also has reverse dispersion.

[0089] Next, a specific configuration of an aerial image display system that displays a superimposed image of a non-floating image and an aerial image as shown in FIG. 3 will be described.

[0090] 11 and 12 are diagrams conceptually showing another example of the aerial image display system of the present invention. 11 and 12 includes an image display device 16, a polarization separation element 18, a half mirror 12, a retardation layer 24, and a reflective linear polarizer 14a. In a preferred embodiment, the aerial image display system 10h also includes an absorptive linear polarizer 26 located closer to the viewer than the reflective linear polarizer 14a. That is, the aerial image display system 10h has, as the reflective polarizer 14, a reflective linear polarizer 14a that transmits linearly polarized light oscillating in a certain direction and reflects linearly polarized light oscillating in a direction perpendicular to this direction.

[0091] In the illustrated example, the polarization separation element 18 has an absorptive linear polarizer 28 and a retardation layer 30. As will be described in detail later, the polarization separation element 18 is either a combination in which the absorptive linear polarizer 28 is either an active polarizer capable of switching the direction of the transmission axis (absorption axis) or a patterned polarizer having a plurality of regions with different directions of the transmission axis (absorption axis), and the retardation layer 30 is a normal retardation layer, or a combination in which the retardation layer 30 is either an active retardation layer capable of switching the direction of the slow axis or the magnitude of retardation, or a patterned retardation layer having a plurality of regions with different directions of the slow axis or the magnitude of retardation, and the absorptive linear polarizer 28 is a normal absorptive linear polarizer.

[0092] When the polarization separation element 18 has an active polarizer or an active retardation layer, the polarization separation element 18 can switch between a state in which it transmits one polarized light of the incident light and absorbs the polarized light orthogonal to the transmitted light, and a state in which it transmits the polarized light orthogonal to the transmitted light and absorbs one polarized light. Hereinafter, such a polarization separation element 18 will also be referred to as a time-division polarization separation element 18.

[0093] When the polarization separation element 18 is a time-division polarization separation element 18, the image display device 16 alternately displays the non-floating image R and the aerial image V1 in a time-division manner in accordance with the switching operation of the polarization separation element 18.

[0094] In such an aerial image display system, when the image display device 16 displays the non-floating image R, the polarization separation element 18 operates to transmit only polarized light that passes through the optical path that results in the non-floating image R and not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and when the image display device 16 displays the aerial image V1, the polarization separation element 18 operates to transmit only polarized light that passes through the optical path that results in the aerial image V1 and not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10h alternately displays the non-floating image R and the aerial image V1, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0095] Furthermore, when the polarization separation element 18 has a patterned polarizer or a patterned retardation layer, the polarization separation element 18 has a plurality of regions that transmit one polarized light of the incident light and absorb the polarized light orthogonal to the first polarized light, and a plurality of regions that transmit the polarized light orthogonal to the first polarized light and absorb one polarized light. Hereinafter, such a polarization separation element 18 is also referred to as a spatially divided polarization separation element 18.

[0096] When the polarization separation element 18 is a spatially divided polarization separation element 18, the image display device 16 displays the non-floating image R and the aerial image V1 by spatially dividing them in accordance with the configuration of the area division of the polarization separation element 18. For example, when the polarization separation element 18 has areas that transmit one polarized light and areas that transmit the other polarized light alternately in a striped pattern, the image display device 16 displays the non-floating image R and the aerial image V1 by spatially dividing them in a striped pattern and arranging them alternately.

[0097] In such an aerial image display system, in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the non-floating image R and blocks the transmission of polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the aerial image V1 and blocks the transmission of polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10h displays the non-floating image R and the aerial image V1 in each region, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0098] The example shown in FIG. 11 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10h. The operation of aerial image display system 10h in this state will be described.

[0099] The image display device 16 emits light that will become an image (aerial image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 28 of the polarization separation element 18 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 28 transmits linearly polarized light in the up-down direction in the figure. Next, this linearly polarized light passes through the retardation layer 30 of the polarization separation element 18 and is converted into circularly polarized light. In the illustrated example, the retardation layer 30 converts the linearly polarized light in the up-down direction into right-handed circularly polarized light.

[0100] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 30 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorbing linear polarizer 28, and is therefore absorbed by the absorbing linear polarizer 28. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and then passes through the retardation layer 24. At that time, it is converted into linearly polarized light by the retardation layer 24. In the illustrated example, as an example, the retardation layer 24 converts the right-handed circularly polarized light into linearly polarized light in the up and down direction.

[0101] The linearly polarized light that has passed through the retardation layer 24 is incident on the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a reflects vertically linearly polarized light, and therefore the linearly polarized light that has entered the reflective linear polarizer 14a is reflected and enters the retardation layer 24. The retardation layer 24 converts the incident vertically linearly polarized light into right-handed circularly polarized light.

[0102] This right-handed circularly polarized light is incident on the half mirror 12 and is partially reflected. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. Furthermore, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensing manner. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into linearly polarized light by the retardation layer 30, transmitted through the absorptive linear polarizer 28, and absorbed by the surface of the image display device 16, etc.

[0103] The left-handed circularly polarized light reflected by the half mirror 12 is incident on the retardation layer 24 and converted into linearly polarized light in the left-right direction. This linearly polarized light is linearly polarized in a direction perpendicular to the linearly polarized light reflected by the reflective linear polarizer 14a, and therefore passes through the reflective linear polarizer 14a. The linearly polarized light that has passed through the reflective linear polarizer 14a is incident on the absorbing linear polarizer 26. The absorbing linear polarizer 26 passes linearly polarized light in the same direction as the linearly polarized light passed through the reflective linear polarizer 14a. Therefore, in the illustrated example, the absorbing linear polarizer 26 passes linearly polarized light in the left-right direction in the figure.

[0104] As described above, the aerial image display system 10h irradiates only the light of the optical path that forms the aerial image V1 toward the user U at the timing when the image display device 16 displays the aerial image V1 or in the area where the aerial image V1 is displayed, thereby preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This prevents the image displayed by the image display device 16 as the aerial image V1 from being displayed as a non-floating image, and allows the image to be displayed only as the aerial image V1.

[0105] Furthermore, in a preferred embodiment, aerial image display system 10h includes an absorptive linear polarizer 26 on the viewing side of reflective linear polarizer 14a. The inclusion of absorptive linear polarizer 26 allows stray light, such as vertically linearly polarized light components that have not been reflected by reflective linear polarizer 14a, to be absorbed by absorptive linear polarizer 26, thereby more reliably preventing unwanted images caused by stray light from being viewed. Furthermore, glare caused by external light being reflected on the surface of aerial image display system 10h can be prevented.

[0106] In a preferred embodiment of the aerial image display system 10h, the absorption axis of the absorbing linear polarizer 28 and the absorption axis of the absorbing linear polarizer 26 are perpendicular to each other. The transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 26 are parallel to each other. Furthermore, at the timing when the aerial image V1 is displayed or in the state of the area where the aerial image V1 is displayed, the slow axis of the retardation layer 30 and the slow axis of the retardation layer 24 are perpendicular to each other. Furthermore, the retardation layer 30 and the retardation layer 24 preferably have the same retardation. Furthermore, it is preferable that the wavelength dispersion characteristics thereof are the same, and it is more preferable that both have reverse dispersion characteristics. The above-described configuration is preferable because it can further reduce stray light such as linearly polarized light components that are not reflected by the reflective linear polarizer 14a.

[0107] On the other hand, the example shown in FIG. 12 shows the timing at which the non-floating image R is displayed or the state of the area where the non-floating image R is displayed in the aerial image display system 10h. The operation of aerial image display system 10h in this state will be described.

[0108] The image display device 16 emits light that forms an image (non-floating image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 28 of the polarization separation element 18 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 28 transmits linearly polarized light in the vertical direction in the figure. This linearly polarized light then passes through the retardation layer 30 of the polarization separation element 18 and is converted into circularly polarized light. In the illustrated example, the retardation layer 30 converts vertically linearly polarized light into left-handed circularly polarized light. That is, in FIGS. 11 and 12, the retardation layer 30 is an active retardation layer or a patterned retardation layer. In the state shown in FIG. 12, the retardation layer 30 has a slow axis oriented in a different direction from that shown in FIG. 11, and the vertically linearly polarized light that passes through the retardation layer 30 is converted into left-handed circularly polarized light, which is opposite to that in the state shown in FIG. 11.

[0109] When this left-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into right-handed circularly polarized light, which then enters the retardation layer 30 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorbing linear polarizer 28, and is therefore absorbed by the absorbing linear polarizer 28. On the other hand, the remaining left-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and then passes through the retardation layer 24. At that time, it is converted into linearly polarized light by the retardation layer 24. In the illustrated example, the retardation layer 24 converts right-handed circularly polarized light into vertically linearly polarized light, and therefore the left-handed circularly polarized light is converted into horizontally linearly polarized light.

[0110] The left-right linearly polarized light converted by retardation layer 24 enters reflective linear polarizer 14a, but is transmitted through reflective linear polarizer 14a because the linearly polarized light is orthogonal to the linearly polarized light reflected by reflective linear polarizer 14a. The linearly polarized light that has transmitted through reflective linear polarizer 14a is transmitted through absorbing linear polarizer 26 and emitted from aerial image display system 10h.

[0111] As described above, at the timing when the aerial image display system 10h displays the non-floating image R or in the area where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0112] In this way, in the aerial image display system 10h, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10h displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0113] 13 and 14 are diagrams conceptually showing another example of the aerial image display system of the present invention.

[0114] 13 and 14 includes an image display device 16, a polarization separation element 18, a half mirror 12, and a reflective circular polarizer 14b. In a preferred embodiment, the aerial image display system 10i also includes an absorptive circular polarizer 32 located closer to the viewing side than the reflective circular polarizer 14b.

[0115] The example shown in FIG. 13 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10i. The operation of the aerial image display system 10i in this state will be described.

[0116] The image display device 16 emits light that will become an image (aerial image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 28 of the polarization separation element 18 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 28 transmits linearly polarized light in the up-down direction in the figure. Next, this linearly polarized light passes through the retardation layer 30 of the polarization separation element 18 and is converted into circularly polarized light. In the illustrated example, the retardation layer 30 converts the linearly polarized light in the up-down direction into right-handed circularly polarized light.

[0117] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 30 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorbing linear polarizer 28, and is therefore absorbed by the absorbing linear polarizer 28. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and enters the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b reflects right-handed circularly polarized light, and therefore the right-handed circularly polarized light that entered the reflective circular polarizer 14b is reflected and enters the half mirror 12.

[0118] A portion of the light incident on the half mirror 12 is reflected. At that time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into linearly polarized light by the retardation layer 30, transmitted through the absorptive linear polarizer 28, and absorbed by the surface of the image display device 16, etc.

[0119] The left-handed circularly polarized light reflected by the half mirror 12 enters the reflective circular polarizer 14b. The reflective circular polarizer 14b reflects right-handed circularly polarized light, and therefore transmits left-handed circularly polarized light. The left-handed circularly polarized light that has passed through the reflective circular polarizer 14b enters the absorbing circular polarizer 32. The absorbing circular polarizer 32 transmits circularly polarized light with the same rotation direction as the circularly polarized light that the reflective circular polarizer 14b transmits, converting it into linearly polarized light. Therefore, in the illustrated example, the absorbing circular polarizer 32 transmits left-handed circularly polarized light. Specifically, the left-handed circularly polarized light that has passed through the reflective circular polarizer 14b enters the retardation layer 24. The retardation layer 24 converts the incident left-handed circularly polarized light into left-handed linearly polarized light. The linearly polarized light that has passed through the retardation layer 24 enters the absorbing linear polarizer 26. The absorbing linear polarizer 26 transmits left-handed linearly polarized light. As a result, the absorptive circular polarizer 32 transmits circularly polarized light having the same rotation direction as the circularly polarized light transmitted by the reflective circular polarizer 14b while converting it into linearly polarized light.

[0120] As described above, the aerial image display system 10i irradiates only the light of the optical path that becomes the aerial image V1 toward the user U at the timing when the image display device 16 displays the aerial image V1 or in the area where the aerial image V1 is displayed, thereby preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This prevents the image displayed by the image display device 16 as the aerial image V1 from being displayed as a non-floating image, and allows the image to be displayed only as the aerial image V1.

[0121] Furthermore, in a preferred embodiment, aerial image display system 10i includes an absorptive circular polarizer 32 on the viewing side of reflective circular polarizer 14b. By including absorptive circular polarizer 32, stray light such as right-handed circularly polarized light components that are not completely reflected by reflective circular polarizer 14b can be absorbed by absorptive circular polarizer 32, thereby more reliably preventing unwanted images caused by stray light from being viewed. Furthermore, glare caused by external light being reflected on the surface of aerial image display system 10i can be prevented.

[0122] In addition, in the aerial image display system 10i, the retardation layer 30 preferably has reverse dispersion. When the retardation layer 30 has reverse dispersion, the light incident on the reflective circular polarizer 14b becomes more ideally circularly polarized light, which is preferable because stray light can be further reduced. For the same reason, it is preferable that the retardation layer 24 also has reverse dispersion.

[0123] On the other hand, the example shown in FIG. 14 shows the timing at which the non-floating image R is displayed or the state of the area in which the non-floating image R is displayed in the aerial image display system 10i. The operation of the aerial image display system 10i in this state will be described.

[0124] The image display device 16 emits light that forms an image (non-floating image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 28 of the polarization separation element 18 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 28 transmits linearly polarized light in the vertical direction in the figure. This linearly polarized light then passes through the retardation layer 30 of the polarization separation element 18 and is converted into circularly polarized light. In the illustrated example, the retardation layer 30 converts vertically linearly polarized light into left-handed circularly polarized light. That is, in FIGS. 13 and 14 , the retardation layer 30 is an active retardation layer or a patterned retardation layer. In the state shown in FIG. 14 , the retardation layer 30 has a slow axis oriented in a different direction from that shown in FIG. 13 , and the vertically linearly polarized light that passes through the retardation layer 30 is converted into left-handed circularly polarized light, which is opposite to that in the state shown in FIG. 13 .

[0125] When this left-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into right-handed circularly polarized light, which then enters the retardation layer 30 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorbing linear polarizer 28, and is therefore absorbed by the absorbing linear polarizer 28. On the other hand, the remaining left-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and enters the reflective circular polarizer 14b. However, since the circularly polarized light has the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer 14b, it passes through the reflective circular polarizer 14b.

[0126] The left-handed circularly polarized light that has passed through the reflective circular polarizer 14b is incident on the absorptive circular polarizer 32. As described above, the absorptive circular polarizer 32 converts the incident left-handed circularly polarized light into linearly polarized light in the left-right direction and transmits it.

[0127] As described above, at the timing when the aerial image display system 10i displays the non-floating image R or in the area where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0128] In this way, in the aerial image display system 10i, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10i displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0129] In the example shown in FIGS. 11 to 14, the polarization separation element 18 is disposed between the image display device 16 and the half mirror 12. In the example shown in FIGS.

[0130] 15 and 16 are conceptual diagrams showing another example of an aerial image display system of the present invention. The aerial image display system 10j shown in Figures 15 and 16 has a polarization separation element 18b made of an active retardation layer or a patterned retardation layer.

[0131] 15 and 16 includes an image display device 16, an absorptive linear polarizer 20, a retardation layer 22, a half mirror 12, a polarization separation element 18b, and a reflective linear polarizer 14a. In a preferred embodiment, the aerial image display system 10j also includes an absorptive linear polarizer 26 located closer to the viewing side than the reflective linear polarizer 14a.

[0132] The example shown in FIG. 15 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10j. The operation of the aerial image display system 10j in this state will be described.

[0133] The image display device 16 emits light that will become an image (aerial image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up-and-down direction in the figure. Next, this linearly polarized light passes through the retardation layer 22 and is converted into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up-and-down direction into right-handed circularly polarized light.

[0134] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 22 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorptive linear polarizer 20, and is therefore absorbed by the absorptive linear polarizer 20. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and then passes through the polarization separation element 18b. The polarization separation element 18b is an active retardation layer or a patterned retardation layer. Therefore, the remaining right-handed circularly polarized light is converted into linearly polarized light by the polarization separation element 18b, which is a retardation layer. In the illustrated example, as an example, the polarization separation element 18b converts the right-handed circularly polarized light into vertically linearly polarized light.

[0135] The linearly polarized light that has passed through the polarization separation element 18b is incident on the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a reflects vertically linearly polarized light, and the linearly polarized light that has entered the reflective linear polarizer 14a is reflected and enters the polarization separation element 18b. The polarization separation element 18b converts the incident vertically linearly polarized light into right-handed circularly polarized light.

[0136] This right-handed circularly polarized light is incident on the half mirror 12 and is partially reflected. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. Furthermore, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensing manner. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into linearly polarized light by the retardation layer 22, transmitted through the absorptive linear polarizer 20, and absorbed by the surface of the image display device 16, etc.

[0137] The left-handed circularly polarized light reflected by the half mirror 12 is incident on the polarization separation element 18b and converted into linearly polarized light in the left-right direction. This linearly polarized light is linearly polarized in a direction perpendicular to the linearly polarized light reflected by the reflective linear polarizer 14a, and therefore passes through the reflective linear polarizer 14a. The linearly polarized light that has passed through the reflective linear polarizer 14a is incident on the absorbing linear polarizer 26. The absorbing linear polarizer 26 passes linearly polarized light in the same direction as the linearly polarized light passed through the reflective linear polarizer 14a. Therefore, in the illustrated example, the absorbing linear polarizer 26 passes linearly polarized light in the left-right direction in the figure.

[0138] As described above, the aerial image display system 10j irradiates only the light of the optical path that forms the aerial image V1 toward the user U at the timing when the image display device 16 displays the aerial image V1 or in the area where the aerial image V1 is displayed, thereby preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This prevents the image displayed by the image display device 16 as the aerial image V1 from being displayed as a non-floating image, and allows the image to be displayed only as the aerial image V1.

[0139] Furthermore, in a preferred embodiment, aerial image display system 10j includes an absorptive linear polarizer 26 located closer to the viewing side than reflective linear polarizer 14a. The inclusion of absorptive linear polarizer 26 allows stray light, such as vertically linearly polarized light components that have not been completely reflected by reflective linear polarizer 14a, to be absorbed by absorptive linear polarizer 26, thereby more reliably preventing unwanted images caused by stray light from being viewed. Furthermore, glare caused by external light being reflected on the surface of aerial image display system 10j can be prevented.

[0140] In a preferred embodiment of the aerial image display system 10j, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 26 are perpendicular to each other. The transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 26 are parallel to each other. Furthermore, at the timing when the aerial image V1 is displayed or in the state of the area where the aerial image V1 is displayed, the slow axis of the retardation layer 22 and the slow axis of the polarization separation element 18b are perpendicular to each other. Furthermore, the retardation layer 22 and the polarization separation element 18b preferably have the same retardation, and preferably have the same wavelength dispersion, and more preferably have reverse dispersion. The above-described configuration is preferable because it can further reduce stray light such as linearly polarized light components that are not completely reflected by the reflective linear polarizer 14a.

[0141] On the other hand, the example shown in FIG. 16 shows the timing at which the non-floating image R is displayed or the state of the area where the non-floating image R is displayed in the aerial image display system 10j. The operation of the aerial image display system 10j in this state will be described.

[0142] The image display device 16 emits light that will become an image (non-floating image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up and down direction in the figure. Next, this linearly polarized light passes through the retardation layer 22 and is converted into right-handed circularly polarized light.

[0143] When this right-handed circularly polarized light is incident on the half mirror 12, part of the light is reflected and converted into left-handed circularly polarized light, which then enters the retardation layer 22 and is converted into left-right linearly polarized light. This linearly polarized light is not transmitted through the absorptive linear polarizer 20, and is therefore absorbed by the absorptive linear polarizer 20. On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 passes through the half mirror 12 and then passes through the polarization separation element 18b. As described above, the polarization separation element 18b is an active retardation layer or a patterned retardation layer, and in the state shown in Fig. 16, the polarization separation element 18b has a slow axis whose direction is different from that in the state shown in Fig. 15, and the right-handed circularly polarized light that has passed through the polarization separation element 18b is converted into linearly polarized light in the left-right direction that is orthogonal to that in the state shown in Fig. 15.

[0144] The left-right linearly polarized light converted by polarization separation element 18b is incident on reflective linear polarizer 14a, but is transmitted through reflective linear polarizer 14a because the linearly polarized light is orthogonal to the linearly polarized light reflected by reflective linear polarizer 14a. The linearly polarized light that has transmitted through reflective linear polarizer 14a is transmitted through absorbing linear polarizer 26 and emitted from aerial image display system 10j.

[0145] As described above, at the timing when the aerial image display system 10j displays the non-floating image R or in the region where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0146] In this way, in the aerial image display system 10j, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18b transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18b transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10j displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0147] In the examples shown in FIGS. 11 to 16, the half mirror is disposed on the image display device side, and the reflective polarizer is disposed on the viewing side.

[0148] 17 and 18 are diagrams conceptually showing another example of the aerial image display system of the present invention.

[0149] The aerial image display system 10k shown in Figures 17 and 18 has an image display device 16, an absorptive linear polarizer 20, a reflective linear polarizer 14a, a retardation layer 22, a half mirror 12, and a polarization separation element 18.

[0150] The example shown in FIG. 17 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10k. The operation of the aerial image display system 10k in this state will be described.

[0151] The image display device 16 emits light that forms an image (aerial image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 20 transmits linearly polarized light in the vertical direction in the figure, for example. This linearly polarized light then enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a transmits linearly polarized light in the vertical direction, so the linearly polarized light that enters the reflective linear polarizer 14a is transmitted without being reflected and enters the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light into circularly polarized light. In the illustrated example, the retardation layer 22 converts the vertically linearly polarized light into right-handed circularly polarized light, for example.

[0152] This right-handed circularly polarized light is incident on the half mirror 12, and a portion of it is transmitted therethrough. The right-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the polarization separation element 18. In the illustrated example, the polarization separation element 18 transmits left-handed circularly polarized light and absorbs right-handed circularly polarized light, so the right-handed circularly polarized light that has entered the polarization separation element 18 is absorbed. Specifically, the polarization separation element 18 has a retardation layer 30 and an absorptive linear polarizer 28, and the right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 30. The absorptive linear polarizer 28 absorbs vertically linearly polarized light, so the vertically linearly polarized light is absorbed by the absorptive linear polarizer 28.

[0153] On the other hand, the remaining right-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner.

[0154] The left-handed circularly polarized light reflected by the half mirror 12 enters the retardation layer 22 and is converted into left-handed linearly polarized light. This linearly polarized light enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a reflects left-handed linearly polarized light, so the linearly polarized light that enters the reflective linear polarizer 14a is reflected. The linearly polarized light reflected by the reflective linear polarizer 14a enters the retardation layer 22 and is converted into left-handed circularly polarized light, which then enters the half mirror 12.

[0155] A portion of the left-handed circularly polarized light incident on the half mirror 12 is reflected and converted into right-handed circularly polarized light, which then enters the retardation layer 22 and is converted into vertically linearly polarized light. This linearly polarized light passes through the reflective linear polarizer 14a and the absorptive linear polarizer 20, and is absorbed by the surface of the image display device 16, etc.

[0156] On the other hand, the remaining left-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The left-handed circularly polarized light that transmitted through the half mirror 12 is incident on the polarization separation element 18. The polarization separation element 18 absorbs right-handed circularly polarized light, and therefore transmits the left-handed circularly polarized light. In the illustrated example, the polarization separation element 18 has a retardation layer 30 and an absorptive linear polarizer 28, and the left-handed circularly polarized light that transmitted through the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 30. The absorptive linear polarizer 28 absorbs vertically linearly polarized light, and therefore horizontally linearly polarized light is transmitted through the absorptive linear polarizer 28.

[0157] In this way, the aerial image display system 10k irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0158] In a preferred embodiment of the aerial image display system 10k, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 28 are perpendicular to each other. Furthermore, the transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 20 are parallel to each other. Furthermore, at the timing when the aerial image V1 is displayed or in the state of the region where the aerial image V1 is displayed, the slow axis of the retardation layer 22 and the slow axis of the retardation layer 30 are perpendicular to each other. Furthermore, the retardation layer 22 and the retardation layer 30 preferably have the same retardation. Furthermore, it is preferable that the wavelength dispersion characteristics thereof are the same, and it is more preferable that both have reverse dispersion characteristics. The above-described configuration is preferable because it can further reduce stray light such as the right-handed circularly polarized light component transmitted through the half mirror 12.

[0159] On the other hand, the example shown in FIG. 18 shows the timing at which the non-floating image R is displayed or the state of the area in which the non-floating image R is displayed in the aerial image display system 10k. The operation of the aerial image display system 10k in this state will be described.

[0160] The image display device 16 emits light that becomes an image (non-floating image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in the vertical direction in the figure. Next, this linearly polarized light is incident on the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a transmits linearly polarized light in the vertical direction, so the linearly polarized light that enters the reflective linear polarizer 14a is transmitted without being reflected and enters the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light in the vertical direction into right-handed circularly polarized light.

[0161] This right-handed circularly polarized light enters the half mirror 12, where a portion of it is transmitted. The right-handed circularly polarized light that has passed through the half mirror 12 enters the polarization separation element 18. Because the polarization separation element 18 transmits right-handed circularly polarized light, this right-handed circularly polarized light passes through the polarization separation element 18 and is emitted from the aerial image display system 10k. In the illustrated example, the right-handed circularly polarized light passes through the retardation layer 30 of the polarization separation element 18 and is converted into left-right linearly polarized light. That is, in FIGS. 17 and 18 , the retardation layer 30 is an active retardation layer or a patterned retardation layer. In the state shown in FIG. 18 , the retardation layer 30 has a slow axis whose direction is different from that in the state shown in FIG. 17 . Therefore, the right-handed circularly polarized light that has passed through the retardation layer 30 is converted into left-right linearly polarized light that is orthogonal to that in the state shown in FIG. 17 . The left-right linearly polarized light converted by the retardation layer 30 enters the absorbing linear polarizer 28. Since the absorptive linear polarizer absorbs light linearly polarized in the up-down direction, light linearly polarized in the left-right direction is transmitted through the absorptive linear polarizer .

[0162] On the other hand, some of the right-handed circularly polarized light reflected by the half mirror 12 is converted into left-handed circularly polarized light by the reflection. The left-handed circularly polarized light reflected by the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 22 and enters the reflective linear polarizer 14a. The reflective linear polarizer 14a reflects left-handed linearly polarized light, and therefore this linearly polarized light is reflected. The reflected left-handed linearly polarized light is converted into left-handed circularly polarized light by the retardation layer 22 and enters the half mirror 12.

[0163] A portion of the light incident on the half mirror 12 is transmitted through the half mirror 12. The transmitted left-handed circularly polarized light is incident on the polarization separation element 18. The polarization separation element 18 transmits right-handed circularly polarized light, and therefore absorbs the left-handed circularly polarized light. Specifically, the left-handed circularly polarized light is converted into vertically linearly polarized light as it passes through the retardation layer 30 of the polarization separation element 18, but since the absorbing linear polarizer 28 absorbs vertically linearly polarized light, this vertically linearly polarized light is absorbed by the absorbing linear polarizer 28.

[0164] On the other hand, the left-handed circularly polarized light reflected by the half mirror 12 is converted into linearly polarized light by the retardation layer 22, passes through the reflective linear polarizer 14a and the absorptive linear polarizer 20, and is absorbed by the surface of the image display device 16, etc.

[0165] As described above, at the timing when the aerial image display system 10k displays the non-floating image R or in the region where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0166] In this way, in the aerial image display system 10k, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10k displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0167] 19 and 20 are diagrams conceptually showing another example of the aerial image display system of the present invention.

[0168] An aerial image display system 10m shown in FIGS. 19 and 20 includes an image display device 16, an absorptive linear polarizer 20, a retardation layer 22, a reflective circular polarizer 14b, a half mirror 12, and a polarization separation element 18.

[0169] The example shown in FIG. 19 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10m. The operation of the aerial image display system 10m in this state will be described.

[0170] The image display device 16 emits light that will become an image (aerial image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up-and-down direction in the figure. Next, this linearly polarized light is incident on the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up-and-down direction into right-handed circularly polarized light.

[0171] This right-handed circularly polarized light is incident on the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b transmits right-handed circularly polarized light and reflects left-handed circularly polarized light, so the right-handed polarized light that is incident on the reflective circular polarizer 14b is transmitted without being reflected and then incident on the half mirror 12.

[0172] This right-handed circularly polarized light is incident on the half mirror 12, and a portion of it is transmitted therethrough. The right-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the polarization separation element 18. In the illustrated example, the polarization separation element 18 absorbs right-handed circularly polarized light, and therefore the right-handed circularly polarized light that has entered the polarization separation element 18 is absorbed. Specifically, the polarization separation element 18 has a retardation layer 30 and an absorptive linear polarizer 28, and the right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 30. The absorptive linear polarizer 28 absorbs vertically linearly polarized light, and therefore the vertically linearly polarized light is absorbed by the absorptive linear polarizer 28.

[0173] On the other hand, the remaining right-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner.

[0174] The left-handed circularly polarized light reflected by the half mirror 12 is incident on the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b reflects left-handed circularly polarized light, so the left-handed circularly polarized light incident on the reflective circular polarizer 14b is reflected. The left-handed circularly polarized light reflected by the reflective circular polarizer 14b is incident on the half mirror 12.

[0175] A portion of the left-handed circularly polarized light that is incident on the half mirror 12 is reflected and converted into right-handed circularly polarized light, and then enters the reflective circular polarizer 14b. This right-handed circularly polarized light passes through the reflective circular polarizer 14b, is converted into linearly polarized light by the retardation layer 22, passes through the absorptive linear polarizer 20, and is absorbed by the surface of the image display device 16, etc.

[0176] On the other hand, the remaining left-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The left-handed circularly polarized light that transmitted through the half mirror 12 is incident on the polarization separation element 18. The polarization separation element 18 absorbs right-handed circularly polarized light, and therefore transmits the left-handed circularly polarized light. In the illustrated example, the polarization separation element 18 has a retardation layer 30 and an absorptive linear polarizer 28, and the left-handed circularly polarized light that transmitted through the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 30. The absorptive linear polarizer 28 absorbs vertically linearly polarized light, and therefore horizontally linearly polarized light is transmitted through the absorptive linear polarizer 28.

[0177] In this way, aerial image display system 10m irradiates only the light of the optical path that forms aerial image V1 toward user U, preventing the image displayed by image display device 16 from being perceived as a non-floating image. This allows the image displayed by image display device 16 to be displayed as aerial image V1.

[0178] In the aerial image display system 10m, it is preferable that the retardation layer 22 has reverse dispersion. When the retardation layer 22 has reverse dispersion, the light incident on the reflective circular polarizer 14b becomes more ideally circularly polarized light, which is preferable because it is possible to further reduce stray light. For the same reason, it is also preferable that the retardation layer 30 has reverse dispersion.

[0179] On the other hand, the example shown in FIG. 20 shows the timing at which the non-floating image R is displayed or the state of the area where the non-floating image R is displayed in the aerial image display system 10m. The operation of the aerial image display system 10m in this state will be described.

[0180] The image display device 16 emits light that becomes an image (non-floating image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, as an example, the absorbing linear polarizer 20 transmits linearly polarized light in the up and down direction in the figure. Next, this linearly polarized light is incident on the retardation layer 22. The retardation layer 22 converts the incident linearly polarized light into circularly polarized light. In the illustrated example, as an example, the retardation layer 22 converts the linearly polarized light in the up and down direction into right-handed circularly polarized light.

[0181] This right-handed circularly polarized light is incident on the reflective circular polarizer 14b. In the illustrated example, the reflective circular polarizer 14b transmits right-handed circularly polarized light and reflects left-handed circularly polarized light, so the right-handed polarized light that is incident on the reflective circular polarizer 14b is transmitted without being reflected and then incident on the half mirror 12.

[0182] This right-handed circularly polarized light enters the half mirror 12, where a portion of it is transmitted. The right-handed circularly polarized light that has passed through the half mirror 12 enters the polarization separation element 18. In the illustrated example, the polarization separation element 18 transmits right-handed circularly polarized light, and so the right-handed circularly polarized light passes through the polarization separation element 18 and exits the aerial image display system 10m. In the illustrated example, the right-handed circularly polarized light passes through the retardation layer 30 of the polarization separation element 18 and is converted into left-right linearly polarized light. That is, in FIGS. 19 and 20 , the retardation layer 30 is an active retardation layer or a patterned retardation layer. In the state shown in FIG. 20 , the retardation layer 30 has a slow axis whose direction is different from that in the state shown in FIG. 19 , and the right-handed circularly polarized light that has passed through the retardation layer 30 is converted into left-right linearly polarized light that is orthogonal to that in the state shown in FIG. 19 . The left-right linearly polarized light converted by the retardation layer 30 enters the absorbing linear polarizer 28. Since the absorptive linear polarizer absorbs light linearly polarized in the up-down direction, light linearly polarized in the left-right direction is transmitted through the absorptive linear polarizer .

[0183] On the other hand, some of the right-handed circularly polarized light reflected by the half mirror 12 is converted into left-handed circularly polarized light by reflection. The left-handed circularly polarized light reflected by the half mirror 12 is incident on the reflective circular polarizer 14b. Since the reflective circular polarizer 14b transmits right-handed circularly polarized light and reflects left-handed circularly polarized light, this left-handed circularly polarized light is reflected. The reflected left-handed circularly polarized light is incident on the half mirror 12.

[0184] A portion of the light incident on the half mirror 12 is transmitted through the half mirror 12. The transmitted left-handed circularly polarized light is incident on the polarization separation element 18. The polarization separation element 18 transmits right-handed circularly polarized light, and therefore absorbs the left-handed circularly polarized light. Specifically, the left-handed circularly polarized light is converted into vertically linearly polarized light as it passes through the retardation layer 30 of the polarization separation element 18, but since the absorbing linear polarizer 28 absorbs vertically linearly polarized light, this vertically linearly polarized light is absorbed by the absorbing linear polarizer 28.

[0185] On the other hand, the left-handed circularly polarized light reflected by the half mirror 12 is converted into right-handed circularly polarized light by reflection, passes through the reflective circular polarizer 14b, is converted into linearly polarized light by the retardation layer 22, passes through the absorptive linear polarizer 20, and is absorbed by the surface of the image display device 16, etc.

[0186] As described above, at the timing when the aerial image display system 10m displays the non-floating image R or in the area where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0187] In this way, in the aerial image display system 10m, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10m displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0188] In the examples shown in FIGS. 17 to 20, the polarization separation element 18 is disposed closer to the viewer than the half mirror 12 and the reflective polarizer.

[0189] 21 and 22 are conceptual diagrams showing another example of an aerial image display system of the present invention. The aerial image display system 10n shown in Figures 21 and 22 has a polarization separation element 18b made of an active retardation layer or a patterned retardation layer.

[0190] 21 and 22 includes an image display device 16, an absorptive linear polarizer 20, a reflective linear polarizer 14a, a polarization separation element 18b, and a half mirror 12. In a preferred embodiment, the aerial image display system 10n also includes an absorptive circular polarizer 32 located closer to the viewing side than the half mirror 12.

[0191] The example shown in FIG. 21 shows the timing at which the aerial image V1 is displayed or the state of the area in which the aerial image V1 is displayed in the aerial image display system 10n. The operation of the aerial image display system 10n in this state will be described.

[0192] The image display device 16 emits light that will become an image (aerial image). As described above, the light is emitted from each point (each pixel) of the image display device so as to spread in various directions. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into linearly polarized light in a certain direction. In the illustrated example, the absorbing linear polarizer 20 transmits linearly polarized light in the vertical direction in the figure. This linearly polarized light then enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a transmits linearly polarized light in the vertical direction, so the linearly polarized light that enters the reflective linear polarizer 14a is transmitted without being reflected and enters the polarization separation element 18b.

[0193] The polarization separation element 18b is an active retardation layer or a patterned retardation layer. Therefore, linearly polarized light incident on the polarization separation element 18b is converted into circularly polarized light by the polarization separation element 18b, which is a retardation layer. In the illustrated example, the polarization separation element 18b converts vertically linearly polarized light into right-handed circularly polarized light.

[0194] This right-handed circularly polarized light is incident on the half mirror 12, and a portion of it is transmitted therethrough. The right-handed circularly polarized light that has transmitted through the half mirror 12 is incident on the absorptive circular polarizer 32. In the illustrated example, the absorptive circular polarizer 32 transmits left-handed circularly polarized light and absorbs right-handed circularly polarized light, so the right-handed circularly polarized light that has entered the absorptive circular polarizer 32 is absorbed. Specifically, the absorptive circular polarizer 32 has a retardation layer 24 and an absorptive linear polarizer 26, and the right-handed circularly polarized light that has transmitted through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 24. The absorptive linear polarizer 26 absorbs vertically linearly polarized light, so the vertically linearly polarized light is absorbed by the absorptive linear polarizer 26.

[0195] On the other hand, the remaining right-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. In addition, the half mirror 12 is either a concave mirror, a Fresnel mirror, or a retroreflective member, and therefore reflects the light in a condensed manner.

[0196] The left-handed circularly polarized light reflected by the half mirror 12 is incident on the polarization separation element 18b and converted into linearly polarized light in the left-right direction. The reflective linear polarizer 14a reflects left- and right-linearly polarized light, and the left- and right-linearly polarized light is reflected by the reflective linear polarizer 14a. The left- and right-linearly polarized light reflected by the reflective linear polarizer 14a enters the polarization separation element 18b, where it is converted into left-handed circularly polarized light and then enters the half mirror 12.

[0197] This left-handed circularly polarized light is incident on the half mirror 12 and is partially reflected. At this time, the left-handed circularly polarized light is converted into right-handed circularly polarized light by the reflection. The right-handed circularly polarized light reflected by the half mirror 12 is incident on the polarization separation element 18b and is converted into vertically linearly polarized light. Because this linearly polarized light is linearly polarized in a direction perpendicular to the linearly polarized light reflected by the reflective linear polarizer 14a, it passes through the reflective linear polarizer 14a and the absorptive linear polarizer 20 and is absorbed by the surface of the image display device 16, etc.

[0198] On the other hand, the remaining left-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The left-handed circularly polarized light that passed through the half mirror 12 is incident on the absorbing circular polarizer 32. In the illustrated example, the absorbing circular polarizer 32 transmits left-handed circularly polarized light and absorbs right-handed circularly polarized light, so the left-handed circularly polarized light that entered the absorbing circular polarizer 32 is transmitted and emitted from the aerial image display system 10n. Specifically, the absorbing circular polarizer 32 has a retardation layer 24 and an absorbing linear polarizer 26, and the left-handed circularly polarized light that passed through the half mirror 12 is converted into left-handed linearly polarized light by the retardation layer 24. The absorbing linear polarizer 26 absorbs vertically linearly polarized light, so horizontally linearly polarized light passes through the absorbing linear polarizer 26.

[0199] In this way, the aerial image display system 10n irradiates only the light of the optical path that forms the aerial image V1 toward the user U, preventing the image displayed by the image display device 16 from being perceived as a non-floating image. This allows the image displayed by the image display device 16 to be displayed as the aerial image V1.

[0200] In a preferred embodiment of the aerial image display system 10n, the absorption axis of the absorbing linear polarizer 20 and the absorption axis of the absorbing linear polarizer 26 are perpendicular to each other. The transmission axis of the reflective linear polarizer 14a and the transmission axis of the absorbing linear polarizer 20 are parallel to each other. Furthermore, at the timing when the aerial image V1 is displayed or in the state of the area where the aerial image V1 is displayed, the slow axis of the polarization separation element 18b and the slow axis of the retardation layer 24 are perpendicular to each other. Furthermore, it is preferable that the polarization separation element 18b and the retardation layer 24 have the same phase difference. It is also preferable that the wavelength dispersion characteristics thereof are the same, and it is more preferable that both have reverse dispersion characteristics. The above-described configuration is preferable because it can further reduce stray light such as the right-handed circularly polarized light component transmitted through the half mirror 12.

[0201] On the other hand, the example shown in FIG. 22 shows the timing at which the non-floating image R is displayed or the state of the area where the non-floating image R is displayed in the aerial image display system 10n. The operation of the aerial image display system 10n in this state will be described.

[0202] The image display device 16 emits light that becomes an image (non-floating image). At this time, as described above, the light is emitted so as to spread in various directions from each point (each pixel) of the image display device. The light emitted by the image display device 16 passes through the absorbing linear polarizer 20 and is converted into vertically linearly polarized light. This linearly polarized light then enters the reflective linear polarizer 14a. In the illustrated example, the reflective linear polarizer 14a transmits vertically linearly polarized light, so the linearly polarized light that enters the reflective linear polarizer 14a is transmitted without being reflected and enters the polarization separation element 18b.

[0203] As described above, the polarization separation element 18b is an active retardation layer or a patterned retardation layer, and in the state shown in FIG. 22, the polarization separation element 18b has a slow axis with a different orientation from that in the state shown in FIG. 21, and vertical linearly polarized light that passes through the polarization separation element 18b is converted into left-handed circularly polarized light with a rotation direction opposite to that in the state shown in FIG. 21.

[0204] This left-handed circularly polarized light enters the half mirror 12, and a portion of it is transmitted therethrough. The left-handed circularly polarized light that has passed through the half mirror 12 enters the absorbing circular polarizer 32. In the illustrated example, the absorbing circular polarizer 32 transmits left-handed circularly polarized light and absorbs right-handed circularly polarized light, so the left-handed circularly polarized light that has entered the absorbing circular polarizer 32 is transmitted and emitted from the aerial image display system 10n. Specifically, the absorbing circular polarizer 32 has a retardation layer 24 and an absorbing linear polarizer 26, and the left-handed circularly polarized light that has passed through the half mirror 12 is converted into horizontally linearly polarized light by the retardation layer 24. The absorbing linear polarizer 26 absorbs vertically linearly polarized light, so horizontally linearly polarized light passes through the absorbing linear polarizer 26.

[0205] On the other hand, the remaining left-handed circularly polarized light that is incident on the half mirror 12 is reflected by the half mirror 12. At this time, the left-handed circularly polarized light is converted into right-handed circularly polarized light by the reflection.

[0206] The right-handed circularly polarized light reflected by the half mirror 12 enters the polarization separation element 18b. Since the polarization separation element 18b converts the left-handed circularly polarized light into vertically linearly polarized light, the right-handed circularly polarized light is converted into horizontally linearly polarized light and enters the reflective linear polarizer 14a.

[0207] The reflective linear polarizer 14a reflects left-right linearly polarized light, and the linearly polarized light is reflected by the reflective linear polarizer 14a. The left-right linearly polarized light reflected by the reflective linear polarizer 14a enters the polarization separation element 18b, where it is converted into right-handed circularly polarized light, and then enters the half mirror 12.

[0208] This right-handed circularly polarized light is incident on the half mirror 12 and is partially reflected. At this time, the right-handed circularly polarized light is converted into left-handed circularly polarized light by the reflection. The left-handed circularly polarized light reflected by the half mirror 12 is incident on the polarization separation element 18b and converted into vertically linearly polarized light. Because this linearly polarized light is linearly polarized in a direction perpendicular to the linearly polarized light reflected by the reflective linear polarizer 14a, it passes through the reflective linear polarizer 14a and the absorptive linear polarizer 20 and is absorbed by the surface of the image display device 16, etc.

[0209] On the other hand, the remaining right-handed circularly polarized light that entered the half mirror 12 is transmitted through the half mirror 12. The right-handed circularly polarized light that passed through the half mirror 12 is incident on the absorptive circular polarizer 32. In the illustrated example, the absorptive circular polarizer 32 transmits left-handed circularly polarized light and absorbs right-handed circularly polarized light, so the right-handed circularly polarized light that entered the absorptive circular polarizer 32 is absorbed. Specifically, the absorptive circular polarizer 32 has a retardation layer 24 and an absorptive linear polarizer 26, and the right-handed circularly polarized light that passed through the half mirror 12 is converted into vertically linearly polarized light by the retardation layer 24. The absorptive linear polarizer 26 absorbs vertically linearly polarized light, so the vertically linearly polarized light is absorbed by the absorptive linear polarizer 26.

[0210] As described above, at the timing when the aerial image display system 10n displays the non-floating image R or in the region where the non-floating image R is displayed, only the light of the optical path that results in the non-floating image R is irradiated toward the user U, thereby preventing the image displayed by the image display device 16 from being viewed as an aerial image. This prevents the image displayed by the image display device 16 as the non-floating image R from being displayed as an aerial image, and makes it possible to display only the non-floating image R.

[0211] In this way, in the aerial image display system 10n, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18b transmits only polarized light that passes through the optical path that results in the non-floating image R and does not transmit polarized light that passes through the optical path that results in the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18b transmits only polarized light that passes through the optical path that results in the aerial image V1 and does not transmit polarized light that passes through the optical path that results in the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system 10n displays the non-floating image R and the aerial image V1 in a time-division or space-division manner, thereby displaying a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed.

[0212] In the examples shown in FIGS. 17 to 22, the reflective polarizer is disposed on the image display device side, and the half mirror is disposed on the viewing side.

[0213] The examples shown in FIGS. 15, 16, 21 and 22 are examples in which the polarization separation element 18 is disposed between the half mirror 12 and the reflective polarizer.

[0214] Next, the components of the aerial image display system will be described.

[0215] (half mirror) A half mirror is a concave mirror, a Fresnel mirror, or a retroreflective member that transmits approximately half of the incident light and reflects the remaining half. That is, a half mirror is a concave mirror, a Fresnel mirror, or a retroreflective member whose reflective surface is a semi-reflective and semi-transparent reflective surface. The transmittance of the half mirror is preferably 50±30%, more preferably 50±10%, and most preferably 50%.

[0216] FIG. 24 is a diagram showing a cross section of an example of a half mirror, which is a concave mirror. The half mirror 12a shown in Figure 24 has a transparent support 40 with a concave surface, a reflective surface 42 formed on the concave surface of the support 40, and a coating layer 44 laminated on the surface of the reflective surface 42 opposite to the support 40.

[0217] The support 40 is made of a transparent resin such as polyethylene terephthalate (PET), cycloolefin polymer (COP), or polymethyl methacrylate (PMMA), or glass, and one surface (concave surface) has a recess formed by cutting out a portion of a sphere or paraboloid. The material and forming method of the reflective surface 42 are the same as those of a typical half mirror. For example, the reflective surface 42 can be formed on the concave surface of the support 40 by vapor deposition of a metal such as silver or aluminum. The thickness is preferably 1 to 20 nm, more preferably 2 to 10 nm, and even more preferably 3 to 6 nm. The half mirror 12a semi-transmits and semi-reflects incident light, and has a function of converging the reflected light by forming the reflecting surface 42 in a concave shape.

[0218] In addition, as a preferred embodiment, the half mirror 12a shown in the figures has a coating layer 44 laminated on the surface of the reflective surface 42 opposite the support 40. The coating layer 44 is preferably transparent. It is also preferably made of a material having approximately the same refractive index as the support 40. Furthermore, it is preferable that the surface of the support 40 opposite the reflective surface 42 and the surface of the coating layer 44 opposite the reflective surface 42 are flat surfaces that are parallel to each other.

[0219] Without the coating layer 44, the light passing through the half mirror 12a is bent by the effect of the concave surface of the support 40. Therefore, the image of the light passing through the half mirror 12a is subjected to an enlargement or reduction action. In contrast, by having half mirror 12a have coating layer 44 with approximately the same refractive index as support 40 and making the surfaces of support 40 and coating layer 44 flat and parallel to each other, it is possible to prevent light passing through half mirror 12a from being bent by the effect of the concave surface of support 40, and to prevent the image of light passing through half mirror 12a from being enlarged or reduced. This makes it possible to prevent the non-floating image and / or the aerial image from being enlarged, reduced, or distorted in the aerial image display system of the present invention.

[0220] The refractive index of the support 40 and the refractive index of the coating layer 44 do not need to be exactly the same as long as the above-mentioned effect is obtained, and there may be a difference between them as long as the effect is achieved. The difference between the refractive index of the support 40 and the refractive index of the coating layer 44 is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less.

[0221] FIG. 25 is a diagram showing a cross section of an example of a half mirror of a retroreflective member. The half mirror 12b shown in Figure 25 has a transparent support 40 with a corner cube array formed on its surface, a reflective surface 42 formed on the corner cube array of the support 40, and a coating layer 44 laminated on the surface of the reflective surface 42 opposite to the support 40.

[0222] FIG. 26 shows a plan view of an example of a corner cube array, and FIG. 27 shows a perspective view of the example of a corner cube array. As shown in Figures 26 and 27, a corner cube array is a structure in which a large number of three-sided mirrors (also called corner cube prisms), each with three mirrors that intersect at right angles to each other, are arranged on a flat surface. From the perspective of improving the resolution of the aerial image, it is preferable that each side of the three-sided mirrors be smaller than 1 mm. Light incident on one of the three-sided mirrors of the corner cube array is reflected sequentially by each of the three mirror surfaces and emitted in the direction opposite to the incident direction. In other words, it is retroreflected.

[0223] The support 40 is made of a transparent resin such as polyethylene terephthalate (PET), cycloolefin polymer (COP), or polymethyl methacrylate (PMMA), or glass, and has a corner cube array known as a retroreflective member. The material and method of forming the reflective surface 42 are the same as those of a typical half mirror. For example, the reflective surface 42 can be formed by vapor deposition of a metal such as silver or aluminum on the surface of the support 40 on which the corner cube array is formed. The thickness is preferably 1 to 20 nm, more preferably 2 to 10 nm, and even more preferably 3 to 6 nm. The half mirror 12b semi-transmits and semi-reflects incident light, and has a function of retroreflecting reflected light by virtue of the reflecting surface 42 being formed on the corner cube array.

[0224] Furthermore, in a preferred embodiment, the half mirror 12b shown in the figures also has a coating layer 44 laminated on the surface of the reflective surface 42 opposite to the support 40. The coating layer is preferably transparent, and the difference in refractive index between the support 40 and the coating layer 44 is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less.

[0225] In the illustrated example, the half mirror 12b is a half mirror of a retroreflective member consisting of a corner cube array, but this is not limited to this, and it may also be a glass bead type retroreflective member whose reflective surface is a semi-transparent, semi-reflective reflective surface.

[0226] FIG. 28 is a cross-sectional view showing an example of a half mirror of a Fresnel mirror. The half mirror 12c shown in Figure 28 has a transparent support 40 in which Fresnel lens-shaped grooves are formed, a reflecting surface 42 formed on the surface of the support 40 where the Fresnel lens is formed, and a coating layer 44 laminated on the surface of the reflecting surface 42 opposite to the support 40.

[0227] The support 40 is made of a transparent resin such as polyethylene terephthalate (PET), cycloolefin polymer (COP), or polymethyl methacrylate (PMMA), or glass, and has a known Fresnel lens shape on one side. The material and forming method of the reflective surface 42 are the same as those of a typical half mirror. For example, the reflective surface 42 can be formed by vapor deposition of a metal such as silver or aluminum on the surface of the support 40 on which the Fresnel lens-shaped grooves are formed. The thickness is preferably 1 to 20 nm, more preferably 2 to 10 nm, and even more preferably 3 to 6 nm. The half mirror 12c semi-transmits and semi-reflects incident light, and has a function of converging reflected light in the same manner as a concave mirror, since the reflecting surface 42 is formed in the shape of a Fresnel mirror.

[0228] Furthermore, in a preferred embodiment, the half mirror 12c shown in the figures also has a coating layer 44 laminated on the surface of the reflective surface 42 opposite to the support 40. The coating layer is preferably transparent, and the difference in refractive index between the support 40 and the coating layer 44 is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less.

[0229] (reflective polarizer) There is no limitation on the reflective polarizer, and various known reflective polarizers can be used. Reflective polarizers are basically linear or circular reflective polarizers.

[0230] A reflective linear polarizer is a polarizer that transmits linearly polarized light in a certain direction and reflects linearly polarized light in a direction perpendicular to the transmitted linearly polarized light. Examples of reflective linear polarizers include a film obtained by stretching a dielectric multilayer film, as described in JP 2011-053705 A, and a wire-grid polarizer, as described in JP 2015-028656 A. Commercially available reflective linear polarizers can also be suitably used. Examples of commercially available reflective linear polarizers include a reflective polarizer (product name APF) manufactured by 3M and a wire-grid polarizer (product name WGF) manufactured by AGC.

[0231] A reflective circular polarizer is a polarizer that transmits right-handed or left-handed circularly polarized light and reflects circularly polarized light that has the opposite rotation direction to the transmitted circularly polarized light. An example of a reflective circular polarizer is a reflective circular polarizer having a cholesteric liquid crystal layer. The cholesteric liquid crystal layer is a liquid crystal phase formed by fixing a cholesterically oriented liquid crystal phase (cholesteric liquid crystal phase).

[0232] As is well known, a cholesteric liquid crystal layer has a helical structure in which liquid crystal compounds are spirally rotated and stacked, and the structure in which liquid crystal compounds are spirally rotated and stacked one turn (360° rotation) is defined as one helical pitch (helical pitch), and the helically rotated liquid crystal compounds are stacked at multiple pitches. A cholesteric liquid crystal layer reflects right-handed or left-handed circularly polarized light in a specific wavelength range and transmits other light, depending on the length of the helical pitch and the sense of rotation of the helix by the liquid crystal compound. Therefore, when the aerial image display system displays a color image, the reflective circular polarizer may have multiple cholesteric liquid crystal layers, such as a cholesteric liquid crystal layer having a central wavelength that selectively reflects red light, a cholesteric liquid crystal layer having a central wavelength that selectively reflects green light, and a cholesteric liquid crystal layer having a central wavelength that selectively reflects blue light.

[0233] (Polarization separation element) A polarization splitter has a function of splitting at least a part of incident light into mutually orthogonal polarized light, for example, into right-handed circularly polarized light and left-handed circularly polarized light, or into mutually orthogonal linearly polarized light. As described above, the polarization separation element preferably has any one of an active retardation layer, a patterned retardation layer, an active polarizer, and a patterned polarizer.

[0234] The active retardation layer is a retardation layer that can switch the direction of the slow axis or the magnitude of retardation. Various known active retardation layers for switching the direction of the slow axis can be used. One example is an active retardation layer that uses a liquid crystal cell acting as a quarter-wave plate and switches the direction of the slow axis (optical axis of a liquid crystal compound) to directions perpendicular to each other by switching the applied voltage, as in an active shutter type stereoscopic image display device. On the other hand, various known active retardation layers that switch the magnitude of retardation are also available. One example is an active retardation layer that uses a liquid crystal cell such as a VA (Vertical Alignment) system and switches between a state where the retardation is zero and a state where the retardation is 1 / 2 wavelength by switching the applied voltage.

[0235] In the present invention, the quarter-wave plate (quarter-wave retardation plate) is a retardation plate having a retardation of approximately a quarter wavelength at any wavelength of visible light. A preferred example of the quarter wave plate is one having a phase difference of 120 nm to 150 nm at a wavelength of 550 nm, and a more preferred example is one having a phase difference of 130 nm to 140 nm.

[0236] The patterned retardation layer has a plurality of regions with different slow axis directions and / or different retardation magnitudes. An example of a patterned retardation layer having different slow axis directions is a quarter-wave plate, which is divided into stripe-shaped regions and has adjacent regions with perpendicular slow axis directions.An example of a patterned retardation layer having different retardations is a patterned retardation layer which is similarly divided into stripe-shaped regions and has quarter-wave regions and three-quarter-wave regions alternately formed. Such a patterned retardation layer may be produced by a known method such as the method described in JP-A-2012-008170 and the method described in JP-A-2012-032661. In addition, commercially available patterned retardation layers may also be used.

[0237] In the above examples, an active retardation layer that switches the direction of the slow axis and a patterned retardation layer having multiple regions with different directions of the slow axis are described as representative examples, but similar effects can also be obtained with an active retardation layer that switches the magnitude of retardation and a patterned retardation layer having multiple regions with different magnitudes of retardation.

[0238] An active polarizer is a polarizer that can switch the direction of its transmission or absorption axis. For example, an active polarizer can switch the direction of its absorption axis (transmission axis) between two orthogonal directions. Various known active polarizers are also available for such an active polarizer. One example is an active polarizer described in JP 2019-70781 A, in which a guest-host liquid crystal layer having a dichroic dye is sandwiched between a pair of opposing electrode layers, and the alignment direction of the dichroic dye is changed by applying a voltage.

[0239] A patterned polarizer is a polarizer having a plurality of regions with different transmission axis or absorption axis directions. An example of a patterned polarizer is a patterned retardation layer in which the regions are divided into stripes and the transmission axis (absorption axis) directions of adjacent regions are orthogonal to each other. As the patterned polarizer, various known ones can be used, such as a patterned polarizer including two or more regions having different absorption axis directions, as described in JP-A-2009-193014.

[0240] In the patterned retardation layer and the patterned polarizer, the pattern of the regions is not limited to a striped shape. In addition to stripes, checkerboard patterns and the like can also be used for the patterned retardation layer.

[0241] As described above, in the aerial image display system of the present invention, when the polarization separation element has an active retardation layer or an active polarizer, the image display device alternately displays the non-floating image R (image of the non-floating image R) and the aerial image V1 (image of the aerial image V1) in a time-division manner. In other words, if the polarization separation element is an active retardation layer or an active polarizer, when the image display device displays the non-floating image R, the polarization separation element switches the direction of the slow axis or transmission axis (absorption axis) to form the optical path of the non-floating image R. Furthermore, when the image display device displays the aerial image V1, the polarization separation element switches the direction of the slow axis or transmission axis to form the optical path of the aerial image V1.

[0242] On the other hand, when the polarization separation element is a patterned retardation layer or a patterned polarizer, the image display device divides (spatially divides) the non-floating image R (image of the non-floating image R) and the aerial image V1 (image of the aerial image V1) according to the pattern of the polarization separation element, and arranges and displays the images. For example, if the polarization separation element has a striped pattern in which regions whose slow axes or transmission axes are orthogonal to each other are alternately arranged, the image display device divides (spatially divides) the image of the non-floating image R and the image of the aerial image V1 into stripes. Then, the image display device displays the divided non-floating image R in a region where the direction of the slow axis or transmission axis of the polarization separation element 18 is the optical path of the non-floating image R, and displays the divided aerial image V1 in a region where the direction of the slow axis or transmission axis of the polarization separation element 18 is the optical path of the aerial image V1.

[0243] Here, in Figures 7 to 10 and Figures 15 to 22, when the image display device 16 is a device having a linear polarizer, such as a liquid crystal display device or an OLED having an anti-reflection film including an absorptive linear polarizer, the absorptive linear polarizer 20 arranged adjacent to the image display device may be the linear polarizer that the image display device has.

[0244] Furthermore, in the examples shown in Figures 11 to 14 and Figures 17 to 20, the polarization separation element 18 has been described as having an absorptive linear polarizer 28 that is a normal linear polarizer and an active retardation layer or a patterned retardation layer as the retardation layer 30, but the retardation layer 30 may be a normal retardation layer and the absorptive linear polarizer 28 may be an active polarizer or a patterned polarizer.

[0245] Similarly, in this configuration, in the aerial image display system, at the timing or in the region where the image display device 16 displays the non-floating image R, the polarization separation element 18 transmits only polarized light that passes through the optical path that becomes the non-floating image R and blocks polarized light that passes through the optical path that becomes the aerial image V1, thereby displaying only the non-floating image R, and at the timing or in the region where the image display device 16 displays the aerial image V1, the polarization separation element 18 transmits only polarized light that passes through the optical path that becomes the aerial image V1 and blocks polarized light that passes through the optical path that becomes the non-floating image R, thereby displaying only the aerial image V1. The aerial image display system can display a superimposed image V2 in which the non-floating image R and the aerial image V1 are superimposed by displaying the non-floating image R and the aerial image V1 in a time-division or space-division manner.

[0246] In a liquid crystal display device, two linear polarizers are usually arranged in a crossed Nicol configuration, sandwiching a liquid crystal cell. Therefore, in a configuration in which a polarization separation element 18 is arranged between an image display device and a half mirror 12 as in the examples shown in Figures 11 to 14, when a liquid crystal display device is used as the image display device and an active polarizer or a patterned polarizer is used, it is necessary to change not only the polarizer on the output side but also the polarizer on the side where backlight is incident to an active polarizer or a patterned polarizer. Considering this point, the configuration using an active polarizer and the configuration using a patterned polarizer are more advantageous when using a display device other than a liquid crystal display device as the image display device, for example, when using an OLED as the image display device.

[0247] In the aerial image display system of the present invention, the position where the aerial image V1 is displayed, i.e., the floating distance of the aerial image V1, can be adjusted by changing the distance between the image display device and the half mirror, the image display device and the reflective polarizer, or the half mirror and the reflective polarizer. Specifically, the floating distance of the aerial image V1 can be increased by increasing any of the above distances.

[0248] Furthermore, as in the examples shown in Figures 15 to 20, when the polarization separation element and the image display device are separated by a half mirror, if a patterned retardation layer or patterned polarizer is used as the polarization separation element, image crosstalk is likely to occur and image quality is likely to deteriorate. Therefore, in a configuration in which the image display device and the polarization separation element are separated with a half mirror sandwiched therebetween, it is preferable to use an active retardation layer or an active polarizer as the polarization separation element 18.

[0249] [Input System] The aerial image display system of the present invention can be combined with a non-contact touch sensor to form an input system. 23 , an input system 50 includes an aerial image display system 10 and a non-contact touch sensor 52 disposed on the display surface side of the aerial image display system 10, and displays an aerial image V1 displayed by the aerial image display system 10 in a space where the non-contact touch sensor 52 determines an input. This allows the user to visually confirm the space where the input is determined by the aerial image V1 when performing a touch in the air using the non-contact touch sensor 52, thereby making the operation easier. For example, a user U can perform a touch operation using the non-contact touch sensor 52 by touching the space where the aerial image V1 is displayed with his / her finger.

[0250] When an aerial image display system is used in such an input system, it may be an aerial image display system that displays only the aerial image V1 and does not display the non-floating image R, as shown in Figures 7 to 10, or an aerial image display system that displays aerial image V1 and non-floating image R, which are separate images, superimposed on each other, as shown in Figures 11 to 22, or an aerial image display system that displays the same image as a non-floating image and an aerial image, as shown in the example of Figure 2.

[0251] Examples of non-contact touch sensors that can be used include infrared non-contact touch sensors that identify objects by emitting infrared light and detecting the reflected infrared light, capacitive non-contact touch sensors, TOF (Time of flight) sensors, LIDAR sensors, and non-contact touch sensors that photograph a finger or the like using one or more cameras to detect the touch position.

[0252] 23, the non-contact touch sensor 52 is configured to be arranged on the display surface side of the aerial image display system 10, but this is not limiting and the non-contact touch sensor 52 may be configured to be arranged on the periphery (bezel) of the aerial image display system 10 depending on the type of non-contact touch sensor 52. For example, when a capacitance type non-contact touch sensor or the like is used, it is preferable to arrange it on the display surface side of the aerial image display system 10. On the other hand, when a TOF sensor, LIDAR sensor, or the like is used, it is preferable to arrange it on the periphery (bezel) of the aerial image display system 10.

[0253] The above describes in detail the aerial image display system and input system of the present invention, but the present invention is not limited to the above examples, and various improvements and modifications may of course be made within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0254] The present invention can be suitably used in car navigation systems, input systems, and the like. [Explanation of symbols]

[0255] 10, 10a-10n Aerial image display system 12, 12a~12c Half mirror 14 Reflective polarizer 14a Reflective linear polarizer 14b Reflective circular polarizer 16 Image display devices 18, 18b Polarization separation element 20, 26 Absorptive linear polarizer 22, 24 Retardation plate 28 Absorptive Linear Polarizer 30 Retardation plate 32 Absorptive circular polarizer 40 Support 42 Reflective surface 44 Covering layer 52 Non-contact touch sensor R Non-floating image V1 aerial image V2 overlay image U user O object

Claims

1. a reflective polarizer; Half mirror and an image display device; a polarization separation element having a function of separating incident light into polarized light that is orthogonal to each other, The half mirror is any one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member, the reflective polarizer and the half mirror are disposed on the viewing side of the image display device, The polarization separation element has either an active retardation layer capable of switching the direction of the slow axis or the magnitude of retardation, a patterned retardation layer having a plurality of two types of regions in which at least one of the direction of the slow axis and the magnitude of retardation is different, an active polarizer capable of switching the direction of the transmission axis or the absorption axis, or a patterned polarizer having a plurality of two types of regions in which the direction of the transmission axis or the absorption axis is different.

2. the reflective polarizer is a reflective linear polarizer, Further, the optical element has a retardation plate, 2. The aerial image display system according to claim 1, wherein the image display device, the polarization separation element, the half mirror, the retardation plate, and the reflective polarizer are arranged in this order.

3. the reflective polarizer is a reflective circular polarizer, 2. The aerial image display system according to claim 1, wherein the image display device, the polarization separation element, the half mirror, and the reflective polarizer are arranged in this order.

4. the reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, 2. The aerial image display system according to claim 1, wherein the image display device, the absorptive linear polarizer, the retardation plate, the half mirror, the polarization separation element, and the reflective polarizer are arranged in this order.

5. the reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, 2. The aerial image display system according to claim 1, wherein the image display device, the absorptive linear polarizer, the reflective polarizer, the retardation plate, the half mirror, and the polarization separation element are arranged in this order.

6. the reflective polarizer is a reflective circular polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, 2. The aerial image display system according to claim 1, wherein the image display device, the absorptive linear polarizer, the retardation plate, the reflective polarizer, the half mirror, and the polarization separation element are arranged in this order.

7. the reflective polarizer is a reflective linear polarizer, Further, the optical element has an absorptive linear polarizer, 2. The aerial image display system according to claim 1, wherein the image display device, the absorptive linear polarizer, the reflective polarizer, the polarization separation element, and the half mirror are arranged in this order.

8. the reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and two retardation plates, 2. The aerial image display system according to claim 1, wherein the image display device, the absorptive linear polarizer, the retardation plate, the half mirror, the retardation plate, and the reflective polarizer are arranged in this order.

9. a reflective polarizer; Half mirror and an image display device; The half mirror is any one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member, the reflective polarizer and the half mirror are disposed on the viewing side of the image display device, the reflective polarizer is a reflective circular polarizer, the reflective circular polarizer has a cholesteric liquid crystal layer; Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, the image display device, the absorptive linear polarizer, the retardation plate, the half mirror, and the reflective polarizer are arranged in this order; The aerial image display system further includes an absorptive circular polarizer on the viewing side.

10. a reflective polarizer; Half mirror and an image display device; The half mirror is any one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member, the reflective polarizer and the half mirror are disposed on the viewing side of the image display device, the reflective polarizer is a reflective linear polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, an aerial image display system, in which the image display device, the absorptive linear polarizer, the reflective polarizer, the retardation plate, and the half mirror are arranged in this order;

11. a reflective polarizer; Half mirror and an image display device; The half mirror is any one of a semi-reflective semi-transmissive concave mirror, a Fresnel mirror, and a retroreflective member, the reflective polarizer and the half mirror are disposed on the viewing side of the image display device, the reflective polarizer is a reflective circular polarizer, Further, the optical fiber includes an absorptive linear polarizer and a retardation plate, an aerial image display system, in which the image display device, the absorptive linear polarizer, the retardation plate, the reflective polarizer, and the half mirror are arranged in this order;

12. 9. The aerial image display system according to claim 2, further comprising an absorptive linear polarizer located on the viewing side of the reflective polarizer.

13. 12. The aerial image display system according to claim 3, further comprising an absorptive circular polarizer on the viewing side.

14. the half mirror has a support and a reflective surface disposed on a surface of the support, a coating layer having the same refractive index as the support is disposed on the reflecting surface; An aerial image display system according to any one of claims 1 to 13, wherein the surface of the support opposite the reflecting surface and the surface of the coating layer opposite the reflecting surface are flat surfaces parallel to each other.

15. an aerial image display system according to any one of claims 1 to 14; An input system having a non-contact touch sensor.

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