Optical member

Abstract

To provide an optical member that suppresses a decrease in visibility of an exterior allowed to be visible to a user and can be thinned.SOLUTION: An optical member 1 has a mirror 2 for reflecting light, and a switching mirror 3 capable of switching a transmission state for transmitting light and a reflection state for reflecting light. The mirror 2 is disposed in parallel with the switching mirror 3. The switching mirror 3 reflects incidence light L2 at an incidence angle θ to the side of the mirror 2 at a reflection angle φ larger than θ, in a reflection state. The mirror 2 reflects the incidence light L2 to the side of the switching mirror 3 at a reflection angle θ while the incidence light L2 reflected by the switching mirror 3 enters at an incidence angle φ.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an optical member that includes members that function as a pair of mirrors and is capable of guiding and emitting incident light. [Background technology]

[0002] Conventionally, optical components have been known that are used, for example, as blind spot auxiliary devices, by forming a pair of mirrors that are arranged opposite each other, one of which is a mirror that primarily reflects light and the other a half mirror that reflects and transmits light. When external light enters between the pair of mirrors, the external light is reflected and emitted between the pair of mirrors. Half mirrors are made of, for example, evaporated metal films or dielectric multilayer films, but the former have a light absorption rate of 30% or more, reducing the amount of light, while the latter have a low light absorption rate and can reduce light loss, but their reflectance varies depending on the wavelength and incident angle of the light.

[0003] Therefore, a half-mirrorless optical element has been proposed that can suppress a decrease in the amount of light and a change in the brightness and color tone of the outside scene that is visually perceived by the user (for example, JP 2023-28532 A). This half-mirrorless optical element has an exit surface that emits light toward the user, and is composed of multiple flat portions that function as mirrors by total reflection and multiple prism portions that emit light, which can solve the above problem.

[0004] Furthermore, as a half-mirrorless optical member, an optical member using a switching mirror that can be switched between a transmitting state and a reflecting state has been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-22908 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for thinner optical components in this field. All of the optical components described above have a structure in which incident light is specularly reflected at the internal light-guiding portion, so that the angle of incidence and the angle of reflection are equal. Here, the distance between the portions functioning as a pair of mirrors, i.e., the thickness, is T, the angle of incidence and the angle of reflection of the incident light are θ, and the distance the light travels between the portions, i.e., the width, is W. In this case, the thickness T of an optical component is determined by the relationship T = W / 2 tan θ, making it difficult to further reduce its thickness.

[0007] On the other hand, optical elements with an exit surface composed of multiple flat portions and prism portions can be made thinner than other optical elements by tilting the entrance surface that allows external light to enter the interior and increasing the angle of incidence, but the light is emitted toward the user in a pattern due to the multiple prism portions, which can reduce the visibility of the external scene in blind spots.

[0008] In view of the above, an object of the present disclosure is to provide an optical member that can be made thinner while suppressing a decrease in visibility of the outside scene that is visually recognized by a user. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, an optical member includes: a mirror (2) having a first reflective layer (22) that reflects light; a switching mirror (3) having a second reflective layer (33) that can be switched between a transparent state that transmits light and a reflective state that reflects light, and that is arranged parallel to the mirror; The normal direction to the plane of the mirror or switching mirror is defined as the thickness direction (D1), the angle between the direction of propagation of incident light incident on the mirror or switching mirror and the thickness direction is defined as the incident angle, and the angle between the direction of propagation of reflected light reflected by the mirror or switching mirror and the thickness direction is defined as the reflection angle, the first reflective layer has a first inclined surface inclined with respect to a plane of the mirror, and an axis along a normal direction to the first inclined surface is a first tilt axis (ax1); the second reflective layer has a second inclined surface inclined with respect to a plane formed by the switching mirror, and an axis along a normal direction to the second inclined surface is a second tilt axis (ax2); The switching mirror reflects the incident light at an angle of reflection φ greater than the incident angle θ. The mirror reflects incident light at an incident angle φ at a reflection angle θ because the first tilt axis is parallel to the second tilt axis.

[0010] This optical element includes a mirror and a switching mirror arranged parallel to each other. The mirror has a first reflective layer that reflects light, and the switching mirror has a second reflective layer that can be switched between a transparent state that transmits light and a reflective state that reflects light. In addition, when the angle of incidence of incident light is θ, the switching mirror, in the reflective state, reflects the incident light at an angle φ greater than θ. The first tilt axis of the first reflective layer is parallel to the second tilt axis of the second reflective layer, so the mirror reflects incident light at an angle θ, even if the incident light has an angle φ. In this optical element, the switching mirror that emits light toward the user does not have protruding prisms, so that external scene light is not emitted in a pattern that follows the prism arrangement, thereby suppressing a decrease in the visibility of the external scene viewed by the user. In addition, because the angles of incident light and reflected light at the mirror and the switching mirror are different in this optical element, the distance traveled by light traveling back and forth between the mirror and the switching mirror is increased compared to when light is specularly reflected. Therefore, this optical member can be made thinner by shortening the distance between the mirror and the switching mirror in accordance with the increase in the distance traveled by light in one round trip between the mirror and the switching mirror.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing an optical member according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a region II of the mirror in FIG. [Figure 3]10A and 10B are diagrams illustrating an example of a partitioned area of ​​a switching mirror and a circuit board for controlling the partitioned area and the circuit board; [Figure 4] 2 is an enlarged cross-sectional view of a region IV in FIG. 1, showing the switching mirror in a reflective state. FIG. [Figure 5] FIG. 5 is a diagram corresponding to FIG. 4 and is an enlarged cross-sectional view of the switching mirror in a transparent state. [Figure 6] FIG. 10 is an explanatory diagram illustrating a case where a first region of the switching mirror is in a transparent state. [Figure 7] FIG. 10 is an explanatory diagram illustrating a case where a second region of the switching mirror is in a transparent state. [Figure 8] FIG. 10 is an explanatory diagram illustrating a case where the Nth region of the switching mirror is in a transparent state. [Figure 9] 4A and 4B are explanatory diagrams of the width of each region of the switching mirror and the direct incident region. [Figure 10] 10A and 10B are explanatory diagrams of light guide and thickness in an optical member of a comparative example. [Figure 11] 5A to 5C are diagrams illustrating the thinning effect of the optical member according to the first embodiment. [Figure 12] FIG. 6 is a cross-sectional view showing an optical member according to a second embodiment. [Figure 13] 10 is an explanatory diagram of light guiding when one region of the switching mirror is in a transparent state in the optical member of the second embodiment. FIG. [Figure 14] 10A and 10B are explanatory diagrams illustrating light guiding in a final region of an optical member according to a second embodiment. [Figure 15] FIG. 10 is a cross-sectional view showing an optical member according to a third embodiment. [Figure 16] 10A and 10B are explanatory diagrams of light guide in an optical member according to a third embodiment. [Figure 17] FIG. 17 is an enlarged cross-sectional view of an area XVII in FIG. 16, showing a modified example of the mirror. [Figure 18] 17 is an enlarged cross-sectional view of a region XVIII in FIG. 16, showing a modified example of the switching mirror. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0014] (First embodiment) An optical member 1 of a first embodiment will be described with reference to the drawings. The optical member 1 of this embodiment can be used as a blind spot auxiliary device that is attached to, for example, a member or obstacle that blocks a user's field of view and creates a blind spot, and allows the user to view the scene in the blind spot. For example, in the case of an in-vehicle application, the optical member 1 is attached to a pillar of the vehicle in which it is installed, and guides external light from the blind spot created by the pillar to the user's side, allowing the user to view the scene in the blind spot.

[0015] Fig. 1 corresponds to a cross-sectional view taken along line II in Fig. 3. In Fig. 6 to Fig. 9, to make it easier to see whether the multiple regions R1 to RN of the switching mirror 3, which will be described later, are in a transparent state or a reflective state, regions in the reflective state are hatched and regions in the transparent state are shown as white. Also, Fig. 6 to Fig. 9 and Fig. 11 are cross-sectional views corresponding to Fig. 1.

[0016] As shown in FIG. 1 , the optical member 1 includes a mirror 2 that reflects light and a switchable mirror 3 that is arranged parallel to and opposite the mirror 2 and is switchable between a transparent state that transmits light and a reflective state that reflects light. The optical member 1 includes the mirror 2 and the switchable mirror 3 attached to a housing or holding member (not shown), and these two members are held parallel to each other. When light enters the switchable mirror 3 from the rear side of the mirror 2, part of the light is repeatedly reflected by the reflective portion of the switchable mirror 3 and the mirror 2, while part of the light is emitted from the transparent portion of the switchable mirror 3. Thus, the optical member 1 guides light that enters from a blind spot blocked by an obstacle (not shown) between the mirror 2 and the switchable mirror 3, and then emits the light to the outside over a wide area of ​​the switchable mirror 3, allowing the user to see the outside view of the blind spot.

[0017] For ease of explanation, the normal direction to the surface 2a of the mirror 2 and the opposing surface 3a of the switching mirror 3, which face each other, will be referred to as the "thickness direction D1" below, as shown by the arrows in FIG. 1 , i.e., the direction corresponding to the thickness direction of the optical member 1. The state of the optical member 1 or its components viewed from the thickness direction D1 will be referred to as the "top view." The direction along the plane formed by the opposing surface 3a of the switching mirror 3, from an end of the portion of the switching mirror 3 that protrudes from the mirror 2 (e.g., the incident end 3A described below) toward the end opposite the end, will be referred to as the "light guiding direction D2." The light guiding direction D2 can be said to be the direction along which light is guided by the mirror 2 and the switching mirror 3. The thickness direction D1 and the light guiding direction D2 indicated by arrows in FIG. 2 and subsequent figures correspond to the directions indicated by arrows in FIG. 1. For ease of explanation, the plane formed by the thickness direction D1 and the light guiding direction D2 shown in FIG. 1 and other figures will sometimes be referred to as the "light guiding plane."

[0018] As shown in FIG. 6, light incident on the optical element 1 from the outside is referred to as "external scene light L1," and light reflected by the switching mirror 3 is referred to as "incident light L2." Light emitted from the external scene light L1 via the optical element 1 toward the exit surface 3b of the switching mirror 3 is referred to as "exited light L3." In the light-guiding plane, the angle between the traveling direction of light incident on the mirror 2 and the thickness direction D1 and the angle between the traveling direction of light incident on the switching mirror 3 and the thickness direction D1 are referred to as the "incident angle." The light incident on the mirror 2 is light reflected by the switching mirror 3 in the reflective state. The light incident on the switching mirror 3 is the external scene light L1 and the incident light L2 reflected by the mirror 2. In the light-guiding plane, the angle between the traveling direction of light reflected by the mirror 2 and the thickness direction D1 and the angle between the traveling direction of light reflected by the switching mirror 3 and the thickness direction D1 are referred to as the "reflection angle." Furthermore, the angles of incidence and reflection at the switching mirror 3 may be referred to as the "first angle of incidence" and the "first angle of reflection," and those at the mirror 2 may be referred to as the "second angle of incidence" and the "second angle of reflection," respectively.

[0019] The mirror 2 is a reflective member that reflects visible light toward the switching mirror 3 at a reflectance equal to or greater than a predetermined value (for example, but not limited to, 80% or greater). The mirror 2 is paired with the switching mirror 3 and is designed to perform asymmetric reflection by reflecting the incident light L2 at a second reflection angle different from the second incident angle in order to reduce the thickness of the optical member 1. As shown in FIG. 2, the mirror 2 includes a transparent substrate 21, a first reflection layer 22, a light-shielding substrate 23 at least a portion of which is made of a light-shielding material, and an anti-reflection layer 24. The mirror 2 has a configuration in which the light-shielding substrate 23, the first reflection layer 22, the transparent substrate 21, and the anti-reflection layer 24 are stacked in this order, for example. The incident light L2 is incident on the mirror 2 from one surface 2a facing the switching mirror 3 at an incident angle φ, and the incident light L2 is reflected by the first reflection layer 22 at a reflection angle θ (<φ).

[0020] The transparent substrate 21 is made of any light-transmitting material such as glass or resin, and functions as a cover for the first reflective layer 22. The transparent substrate 21 has an anti-reflection layer 24 formed on one surface 2a on the switching mirror 3 side.

[0021] The first reflective layer 22 performs asymmetric reflection by reflecting the incident light L2 at a second reflection angle θ, which is different from the second incident angle φ and is the same as the first incident angle of the external light L1 incident on the switching mirror 3. The first reflective layer 22 has a periodic layer structure, as shown in FIG. 2, in which liquid crystal layers aligned so as to be tilted at a constant angle α with respect to the plane formed by the first surface 2a are repeatedly stacked. The first reflective layer 22 is made of, for example, cholesteric liquid crystal. For example, when the average refractive index of the transparent substrate 21 and the first reflective layer 22 is n (n>1), the second incident angle φ of the incident light L2 changes to φ0 (φ0<φ) due to internal refraction. The mirror 2 has a structure in which the first reflective layer 22 has a refractive index modulation of Δn in the periodic layer structure, and light with an incident angle φ0 is Bragg-reflected on an inclined surface inside the first reflective layer 22 at an inclination angle α. In this case, sinφ / n=sinφ0. Then, in the mirror 2, for example, the incident light L2 that has been Bragg-reflected by the first reflective layer 22 has an internal reflection angle θ=φ=2α at the mirror 2, and the angle at which it is emitted toward the switching mirror 3, i.e., the external reflection angle, returns to θ, the same as the angle of incidence of the external scene light L1 onto the switching mirror 3. At this time, n×sin(φ=2α)=n×sinθ=sinθ. In other words, the mirror 2 serves to return the angle of the incident light L2 that has been asymmetrically reflected by the switching mirror 3 to the angle before reflection by the switching mirror 3. As a result, when the incident light L2 reflected by the switching mirror 3 is finally emitted to the outside from the exit surface 3b of the optical element 1, it returns to θ, the same as the angle of incidence of the external scene light L1, and continuity is ensured between the scene that the user directly views and the scene that the user views through the optical element 1.

[0022] 2, for example, a virtual line passing through the center of incident light L2 and its reflected light on the inclined surface at an angle α is defined as the inclination axis ax1, and the angle between the inclination axis ax1 and the thickness direction D1, i.e., the inclination angle of the layer structure, is defined as α1. The inclination axis ax1 can also be considered as an axis along the normal direction to the inclined surface of the first reflective layer 22. In this case, the inclination angle α1 of the first reflective layer 22 is the same as the inclination angle α2 of the switchable mirror 3, which will be described later.

[0023] The light-shielding substrate 23 is made of, for example, any black material that absorbs visible light, and is configured so that external light L1 from the other surface 2b, which is the surface opposite to the one surface 2a, does not pass through the mirror 2. The light-shielding substrate 23 may be configured to block external light L1 from the other surface 2b, and may be configured such that a light-shielding film made of any black material or the like is formed on a transparent substrate such as glass or a resin material, or a separate light-shielding member is attached to a transparent substrate.

[0024] The antireflection layer 24 is formed on one surface 2a of the mirror 2 facing the switching mirror 3, i.e., on the surface of the transparent substrate 21, to prevent the incident light L2 from being reflected on the one surface 2a and to reduce noise caused by surface reflection. The antireflection layer 24 may be, for example, an antireflection film, or may have a moth-eye structure formed directly on the transparent substrate 21.

[0025] 3, the switching mirror 3 is a light-controlling member that has a plurality of partitioned regions R1 to RN (N: a natural number equal to or greater than 2), and can switch between a transparent state that transmits visible light and a reflective state that reflects visible light for each of the plurality of regions R1 to RN. The switching mirror 3 can also be called a "switching mirror." The plurality of regions R1 to RN can also be called partitioned regions, but the number of such regions can be changed as appropriate.

[0026] For ease of explanation, as shown in Fig. 3, in a top view, one of the two ends of the switching mirror 3 that extend beyond the mirror 2 will be referred to as the "incident end 3A," the other will be referred to as the "terminal end," and the side formed by the incident end 3A will be referred to as the "end side." Furthermore, assuming that the number of regions is N (N: a natural number greater than or equal to 2), the regions will be referred to in order from the incident end 3A toward the terminal end as the first region R1, the second region R2, the third region R3, the fourth region R4, ..., the (N-1)th region R(N-1), and the Nth region RN. Note that the dashed lines in Fig. 3 are for convenience in indicating the boundaries between the regions R1 to RN of the switching mirror 3 and are not actually visible to the user.

[0027] The switching mirror 3 is partitioned so that, for example, the multiple regions R1 to RN are arranged parallel to the edge. In Fig. 3, the switching mirror 3 is rectangular and the multiple regions R1 to RN are oblong in top view, but this is not limiting. For example, the switching mirror 3 and the multiple regions R1 to RN may be parallelograms, and the outlines thereof may be changed as appropriate.

[0028] The switching mirror 3 has wiring 4 such as an FPC connected to transparent electrodes 32 and 34 (described later) in the multiple regions R1 to RN, and is also connected to a circuit board 5 for drive control via the wiring 4. This allows the switching of the switching mirror 3 between a transparent state and a reflective state in each of the multiple regions R1 to RN. The circuit board 5 is, for example, an electronic control unit equipped with a CPU, ROM, RAM, I / O, and other components (not shown) on a board having circuit wiring (not shown). CPU, ROM, RAM, and I / O are abbreviations for Central Processing Unit, Read Only Memory, Random Access Memory, and Input / Output, respectively. The circuit board 5 is, for example, connected to a power source (not shown) and is disposed on the other surface 2b of the mirror 2. The circuit board 5 loads and executes a program for driving and controlling the switching mirror 3, which is stored in advance in a recording medium (not shown), to control the dimming of the switching mirror 3.

[0029] 4, the switching mirror 3 includes a first transparent substrate 31, a first transparent electrode 32, a second reflective layer 33, a second transparent electrode 34, a second transparent substrate 35, and an anti-reflection layer 36. The switching mirror 3 has, for example, the first transparent substrate 31, the first transparent electrode 32, the second reflective layer 33, the second transparent electrode 34, and the second transparent substrate 35 stacked in this order, and the anti-reflection layer 36 formed on an opposing surface 3a facing the mirror 2 and an exit surface 3b opposite thereto.

[0030] The first transparent substrate 31 and the second transparent substrate 35 are made of any light-transmitting material, such as glass or resin. The first transparent substrate 31 corresponds to a cover for the second reflective layer 33, and a first transparent electrode 32 is formed on the surface opposite to the opposing surface 3a that faces the mirror 2. The second transparent substrate 35 corresponds to a base substrate for the second reflective layer 33, and a second transparent electrode 34 is formed on the surface that faces the first transparent substrate 31. An antireflection layer 36 is formed on the opposing surface 3a of the first transparent substrate 31 and on the exit surface 3b of the second transparent substrate 35. The antireflection layer 36 may be, for example, an antireflection film, or may have a moth-eye structure formed directly on the transparent substrates 31 and 35. The antireflection layer 36 prevents reflection on the surfaces of the transparent substrates 31 and 35, thereby suppressing noise caused by surface-reflected light.

[0031] The first transparent electrode 32 and the second transparent electrode 34 are electrodes that are made of any conductive material with transparency, such as ITO (indium tin oxide), and transmit visible light. One or both of the first transparent electrode 32 and the second transparent electrode 34 have a predetermined pattern shape that is partitioned into a plurality of regions R1 to RN, and are configured to allow individual voltage application to the regions R1 to RN.

[0032] The second reflective layer 33, like the first reflective layer 22, is made of, for example, cholesteric liquid crystal and is transparent when a voltage is applied via the transparent electrodes 32 and 34, but is normally reflective. In the reflective state, the second reflective layer 33 reflects visible light at a predetermined reflectance or higher (e.g., 80% or higher, but is not limited thereto) and does not transmit light. As shown in FIG. 4, in the reflective state, the second reflective layer 33 is designed to perform asymmetric reflection by reflecting external light L1 or incident light L2 toward the mirror 2 at a first reflection angle φ (>θ), which is different from the first incident angle θ. Specifically, like the first reflective layer 22, the second reflective layer 33 has a periodic layer structure with a predetermined refractive index modulation, in which liquid crystal layers aligned so as to be tilted at a constant angle α with respect to the plane of the opposing surface 3a are repeatedly stacked. In the switching mirror 3, for example, when the average refractive index of the first transparent substrate 31 and the second reflective layer 33 is n, the incident angle θ of the incident light L2 changes to θ0 due to internal refraction, and the light at the incident angle θ0 is Bragg-reflected on an inclined surface with an inclination angle α inside the second reflective layer 33. At this time, sin θ / n = sin θ0 holds. Then, in the switching mirror 3, the incident light L2 Bragg-reflected by the second reflective layer 33 has an internal reflection angle φ0 = θ0 + 2α, and when it is emitted toward the mirror 2, the external reflection angle is a first reflection angle φ that is larger than the first incident angle θ. At this time, n × sin(θ0 + 2α) = n × sin φ0 = sin φ holds.

[0033] As shown in FIG. 4 , the tilt axis ax2 is a virtual line passing through the center of the incident light L2 and its reflected light on the inclined surface of the second reflective layer 33 having an angle of α. The angle between the tilt axis ax2 and the thickness direction D1, i.e., the tilt angle, is α2. The tilt axis ax2 can also be considered an axis along the normal direction to the inclined surface of the second reflective layer 33. In this case, the tilt angle α2 of the second reflective layer 33 is the same as the tilt angle α1, and the tilt axis ax2 is parallel to the tilt axis ax1. As a result, in the optical element 1, the first angle of incidence at the switching mirror 3 and the second angle of reflection at the mirror 2 are the same (θ), and the first angle of reflection at the switching mirror 3 and the first angle of incidence at the mirror 2 are the same (φ). Therefore, the optical element 1 has a structure in which the angle of incident light L2, which has been changed by reflection at the switching mirror 3, is returned to the original angle of incidence at the switching mirror 3 by asymmetric reflection at the mirror 2. This ensures continuity between the view in the blind spot perceived by the user and the view directly perceived by the user.

[0034] As shown in FIG. 5, in the transparent state, the second reflective layer 33 is controlled by applying a voltage such that the alignment of the liquid crystal material changes, the refractive index becomes uniform within the layer, and the inclined plane does not exist. "Uniform refractive index within the layer" means, for example, that the refractive index is uniform in the thickness direction D1, the light guide direction D2, and the direction perpendicular to the light guide plane formed by these directions. Therefore, in the transparent state, the second reflective layer 33 transmits incident external light L1 or incident light L2 reflected by the mirror 2. In the transparent region of the switching mirror 3, external light L1 or incident light L2 reflected by the mirror 2 at an incident angle θ is refracted internally and then transmitted through the second reflective layer 33. Upon exiting the exit surface 3b, it is refracted again and emitted as exit light L3 at an angle θ.

[0035] During dimming control, a voltage is applied to at least one of the regions R1 to RN of the switching mirror 3, and the region to which the voltage is applied becomes transparent and mainly transmits visible light. Then, the switching mirror 3 performs dimming control in which at least one of the first region R1 to the Nth region RN is made transparent and all the remaining regions are made reflective, and the transparent region is sequentially switched.

[0036] For example, as shown in FIG. 6, at a certain timing, the first region R1 of the switching mirror 3 becomes transparent when a voltage is applied, and the remaining regions become reflective. At this timing, external scene light L1 incident on the first region R1 passes through the first region R1 and is emitted as emitted light L3. Meanwhile, external scene light L1 incident on the other regions is reflected toward the mirror 2 and then repeatedly reflected by the mirror 2 and the switching mirror 3, resulting in being guided in a direction different from that of the external scene light L1 that reached the first region R1. For ease of viewing, in FIG. 6, the external scene light L1 incident on the transparent region of the switching mirror 3 is indicated by a solid line, and the external scene light L1 incident on the reflective region and its reflected light are indicated by a dashed line. This is also true for FIG. 7.

[0037] 7, at another timing, the second region R2 of the switching mirror 3 is switched from the reflective state to the transparent state by application of a voltage, and the remaining regions are in the reflective state. In other words, at the same time that the first region R1 is switched from the transparent state to the reflective state, the second region R2 is switched from the reflective state to the transparent state, and the other regions R3 to RN are maintained in the reflective state. At this time, the external scene light L1 that reaches the second region R2 in the transparent state is emitted from the second region R2 as emitted light L3, and the external scene light L1 that reaches the other regions in the reflective state is guided without being emitted from the switching mirror 3.

[0038] The switching mirror 3 is sequentially switched so that one region becomes transparent at a time. For example, as shown in FIG. 8, at other times, the Nth region RN becomes transparent upon voltage application, and the remaining regions become reflective. At this time, external light L1 is guided by the switching mirror 3 and mirror 2, and incident light L2 that reaches the transparent Nth region RN is directly emitted as emitted light L3, while light that does not reach the Nth region RN is guided in another direction. Note that, for ease of viewing, FIGS. 6 to 8 show simplified views that omit the refraction of external light L1 or incident light L2 inside mirror 2 or switching mirror 3. This also applies to the subsequent drawings.

[0039] In this way, the switching mirror 3 performs dimming control so that at least one of the multiple regions R1 to RN is transparent and all the other regions are reflective, and the transparent region is sequentially changed. As a result, outside light L1 incident between the mirror 2 and the switching mirror 3 is reflected with high reflectivity by the reflective region of the switching mirror 3 and emitted with high transmittance from the transparent region. Furthermore, because the transparent region of the switching mirror 3 is sequentially switched, the outside light L1 or incident light L2 is emitted as emitted light L3 over a wide range, allowing the user to view the outside scene in blind spots. The region of the switching mirror 3 onto which external scene light L1 directly enters, i.e., the region from the incident end 3A to a predetermined position onto which external scene light L1 enters, is referred to as the "direct incidence region." In this case, if the switching mirror 3 has multiple regions R1 and R2 in the direct incidence region as shown in FIG. 6, the optical element 1 may set the number of regions included in the direct incidence region to a transparent state and all remaining regions to a reflective state during light control. In this way, the optical element 1 may set the number of regions to a transparent state at a certain timing to one or more, depending on the number of regions of the switching mirror 3 included in the direct incidence region. 9, the width of the direct incident region in the light guide direction D2 is set to D L1 The width of each of the regions R1 to RN in the light guide direction D2 is P. The optical member 1 has a width P of, for example, D L1 In other words, the optical element 1 may have a width D of the direct incidence region. L1 The width P of each region of the switching mirror 3 and the number of regions may be determined depending on the above. L1 In the case of D = P, the optical element 1 can control the light intensity by sequentially switching the transparent regions among the plurality of regions R1 to RN, while keeping all the other regions in a reflective state. L1 In the case of >P, when the direct incident area contains k areas (k is an integer of 2 or more), the dimming control is L1By controlling the light intensity in this way, one or more areas located in the direct incident area can be simultaneously made transparent or reflective, thereby improving the efficiency of light guide at mirror 2 and switching mirror 3.

[0040] The above is the basic configuration of the optical member 1. Compared to a configuration in which a pair of mirrors guides part of the external light L1 and the incident light L2 by specular reflection (hereinafter referred to as the "comparative example"), the optical member 1 can have a shorter distance between the pair of mirrors, i.e., can be made thinner.

[0041] Specifically, as shown in FIG. 10 , the comparative example has a pair of mirrors 100, 110, in which a portion of external scene light L1 is specularly reflected by the half mirror 110, and this specularly reflected light is then specularly reflected by the mirror 100. In the comparative example, another portion of the external scene light L1 or the specularly reflected light is emitted to the outside from the half mirror 110. Here, the pair of mirrors 100, 110 are arranged parallel to each other, and the distance between them, i.e., the thickness of the optical member of the comparative example, is defined as T0, and the angle of incidence and angle of reflection of light on the pair of mirrors are defined as θ. In this case, if the width of light traveling along the plane of the mirrors 100 as it makes a round trip between the pair of mirrors 100, 110 is defined as W, then W is 2T0 tan θ. As shown in FIG. 10, the width of the direct incidence area from one end of the half mirror 110 in the light guide direction D2 is defined as a direct incidence width D L1 and the width of the half mirror 110 in the same direction is X. The direct incident width D L1 is the width that allows external scene light L1 to be taken into the optical member, and affects the average brightness of the light emitted from the half mirror 110. For example, in the comparative example, when the efficiency in reflection and transmission is 100%, the average brightness of the emitted light L3 is D L1 The actual scene ratio is the ratio of the brightness of the scene viewed with the emitted light L3 to the brightness of the scene viewed without passing through the optical element. L1When it coincides with the reciprocating width W, in the comparative example, since there is no loss of light rays, light can be guided most efficiently and the average brightness described above is obtained.

[0042] On the other hand, the optical member 1 is configured such that light incident on the switching mirror 3 at an incident angle θ is reflected at a reflection angle φ, and light incident on the mirror 2 at an incident angle φ is reflected at a reflection angle θ. Here, for example, as shown in FIG. 11, the distance that light travels along the light guiding direction D2 when light makes a round trip between the switching mirror 3 and the mirror 2, that is, the reciprocating width, is set to the same W as in the comparative example. Also, at this time, the distance in the thickness direction D1 between the first reflection layer 22 of the mirror 2 and the second reflection layer 33 of the switching mirror 3, that is, the thickness, is set to T. Also, the width of the direct incidence region from the incident end portion 3A of the switching mirror 3 is made the same D as in the comparative example L1 and the width of the switching mirror 3 in the light guiding direction D2 is made the same X as in the comparative example. At this time, W = T(tanθ + tanφ) = 2T0tanθ, but as described above, since φ > θ, (tanθ + tanφ) > 2tanθ, and T < T0 holds. That is, the optical member 1 has a structure that is thinner than the comparative example in which light is specularly reflected by the pair of mirrors 100 and 110 by having an asymmetric reflection configuration in the mirror 2 and the switching mirror 3. Also, the optical member 1 has a direct incidence width D in the switching mirror 3 L1 is the same as in the comparative example, so the average brightness of the emitted light L3 is maintained at the same level or higher than in the comparative example.

[0043] Next, preferable dimming control will be described. Let C (unit: Hz) be the temporal resolution of human vision, and the time required for the switching control to make each region from the first region R1 to the Nth region RN transparent once be the "full-surface switching time". At this time, for the switching mirror 3, with the full-surface switching time being S (unit: sec), in the dimming control, it is preferable to satisfy S < 1 / C.

[0044] The full-area switching time S refers to the total time for which all areas are transparent, with the time during which each of the areas R1 to RN is in a transparent state due to a single voltage application being defined as the "transparent time." In other words, it is preferable for the full-area switching time to be equal to or shorter than the time resolution of human vision (for example, 1 / 30 seconds or less). For example, the full-area switching time S of the switching mirror 3 is preferably 1 / 30 seconds or less, and more preferably 1 / 60 seconds or less. This allows the switching mirror 3 to be in a state where the user is not aware of the full-area switching between the transparent state and the reflective state of the multiple areas R1 to RN, i.e., does not feel uncomfortable due to the light control. Furthermore, the above-described light control by the switching mirror 3 allows the user to view the outside scenery through the transmitted light of each of the multiple areas R1 to RN, i.e., the transmitted light of the entire exit surface 3b.

[0045] The switching mirror 3 can individually control the transparent time of each region by changing the duration of voltage application in each of the multiple regions R1 to RN. For example, the transparent times of the first region R1, the second region R2, ..., the K-th region RK, ..., the (N-1)-th region R(N-1), and the N-th region RN can be set as t1, t2, ..., t K , t (N-1) , t N Then, the full screen switching time S is expressed by the following formula (1): where K is an integer from 1 to N, and the transparent times t1 to t N is approximately the same as the current application time in each region.

[0046]

number

[0047] I1=T m ×t1 / S (2) I2=R m ×R f ×T m ·t2 / S···(3) I N =R m (N-1) ×R f (N-1) ×T m ×t N / S···(4) In other words, the transparent time t1~t N The length of the transparent time t1 to t2 is proportional to the brightness of the outside scene visually recognized by the user in each of the first region R1 to the Nth region RN. N By appropriately changing the light intensities I1 to I2 of the first region R1 to the Nth region RN, N For example, if it is desired to make the light amounts of the first region R1 and the second region R2 equal, it is sufficient to satisfy the following expressions (5) and (6).

[0048] I2=I1×R m ×R f ×t2 / t1 (5) t2=t1 / (R m ×R f )···(6) A similar relationship holds for the third region R3 and subsequent regions, so if you want to make the light intensity I3 in the third region R3 equal to the light intensity in the first region R1 and the second region R2, you just need to satisfy the following equations (7) and (8).

[0049] I3=I2×R m ×R f ×t3 / t2=I1×R m 2 ×R f 2 ×t3 / t1···(7) t3=t1 / (R m 2 ×R f 2 )···(8) Similarly, the light intensity I Nis desired to be equal to the light amount in each of the first region R1 to the (N-1)th region R(N-1), the following formulas (9) and (10) should be satisfied.

[0050] I N =I (N-1) ×R m ×R f ×t N / t (N-1) =I1×R m (N-1) ×R f (N-1) ×t N / t1···(9) t N =t1 / (R m (N-1) ×R f (N-1) )···(10) By performing dimming control that satisfies the formula (10), the switching mirror 3 equalizes the amount of emitted light in each of the regions R1 to RN, thereby making it possible to equalize the brightness of the outside scene that the user sees.

[0051] According to this embodiment, the optical member 1 includes a mirror 2 and a switching mirror 3 arranged in parallel. The switching mirror 3 can be switched between a transparent state in which light is transmitted and a reflective state in which light is reflected, resulting in an optical member 1 configured such that the mirror 2 and the switching mirror 3 reflect light asymmetrically. In the optical member 1, the switching mirror 3 emits a portion of the outside scene light L1 or incident light L2 at an incident angle θ from the exit surface 3b and reflects the other portion at a reflection angle φ (>θ). The mirror 2 reflects the incident light L2 at the incident angle φ at a reflection angle θ. In the optical member 1, the multiple regions R1 to RN of the switching mirror 3 are switched between the transparent state and the reflective state in a time-division manner. There is no region on the exit surface 3b that does not emit light, and patterned light is not emitted from the exit surface 3b, thereby suppressing a decrease in visibility of the outside scene viewed by the user. Furthermore, the optical element 1 is configured such that, because the angles of incident light and reflected light at the mirror 2 and the switching mirror 3 are different, the distance traveled by light when it travels back and forth between the mirror 2 and the switching mirror 3 increases compared to when light is specularly reflected. This allows the optical element 1 to shorten the distance between the mirror 2 and the switching mirror 3 in accordance with the increase in the distance traveled by light in one round trip between the mirror 2 and the switching mirror 3, thereby enabling a thinner optical element. Furthermore, the optical element 1 ensures that the angle of light transmitted through the switching mirror 3 is the same as the angle of incidence on the switching mirror 3, and that the reflected light that is asymmetrically reflected by the switching mirror 3 returns to its original angle of incidence due to asymmetric reflection on the mirror 2, thereby ensuring continuity between the view in the blind spot that is visible to the user and the outside scene.

[0052] (Second embodiment) An optical member 1 according to a second embodiment will now be described. Figures 12 and 13 are cross-sectional views corresponding to Figure 1.

[0053] 12, the optical member 1 of this embodiment differs from the first embodiment in that the area where the user can view the outside scene using the optical member 1 is defined as a viewing area RV, and the switching mirror 3 is not disposed in an end area RVN of the viewing area RV. This difference will be mainly described in this embodiment.

[0054] In this embodiment, as shown in FIG. 12, the switching mirror 3 is disposed so that one end in the light guiding direction D2 protrudes from the mirror 2, and this end serves as an incident end 3A. For example, in a top view, the switching mirror 3 has an end portion opposite the incident end 3A that is disposed inside the outer periphery of the mirror 2 and is not disposed in a region RVN (described below) in the viewing region RV that is located farthest from the incident end 3A. In this embodiment, the switching mirror 3 is partitioned into (N-1) regions R1 to R(N-1), which is one less than the number of regions in the viewing region RV. When the switching mirror 3 outputs the output light L3 to a region in the viewing region RV other than the region RVN, as shown in FIG. 13, for example, at least one of the regions R1 to R(N-1) is controlled to a transparent state. When the switching mirror 3 outputs the incident light L2 to the region RVN, as shown in FIG. 14, for example, no voltage is applied to the switching mirror 3, and all of the regions R1 to R(N-1) are in a reflective state. That is, in this embodiment, the switching mirror 3 performs the same dimming control as in the first embodiment for the regions R1 to R(N-1), which are one or more regions less than in the first embodiment, except that the switching mirror 3 is not energized when emitting light to, for example, the region RVN. As a result, the optical member 1 has a structure in which the dimming control is simpler than in the first embodiment, and is more compact in the light guiding direction D2.

[0055] The visible region RV is a region that allows the user to view the outside scene using the emitted light L3 that is emitted via the switching mirror 3 or the incident light L2 that is reflected by the mirror 2 and is emitted without passing through the switching mirror 3. The visible region RV is partitioned into N regions RV1 to RVN, for example, from the incident end 3A side, such as a first region RV1, a second region RV2, ..., an (N-1)th region RV(N-1), and an Nth region RVN. The multiple regions RV1 to RVN have, for example, approximately equal widths in the light guiding direction D2, and emit light that has made a different number of round trips between the mirror 2 and the switching mirror 3. Hereinafter, for ease of explanation, the number of round trips of light between the mirror 2 and the switching mirror 3 will be simply referred to as the "number of round trips."

[0056] For example, in the first region RV1, outside scene light L1 that reaches the first region R1 of the switching mirror 3 in the transparent state, i.e., light that has made zero round trips, is emitted as output light L3, allowing the user to view the outside scene. For example, in the second region RV2, incident light L2 that reaches the second region R2 of the switching mirror 3 in the transparent state, i.e., light that has made one round trip, is emitted as output light L3, allowing the user to view the outside scene. For example, in the (N-1)th region RV(N-1), incident light L2 that reaches the (N-1)th region R(N-1) of the switching mirror 3 in the transparent state, i.e., light that has made (N-2) round trips, is emitted as output light L3, allowing the user to view the outside scene. And, in the Nth region RVN, as shown in FIG. 14, light that has made (N-1) round trips out of the incident light L2 passes through a region where the switching mirror 3 is not disposed and is emitted as output light L3, allowing the user to view the outside scene. In the above description, the widths of the regions R1 to R(N-1) of the switching mirror 3 in the light guide direction are the widths of each region in the visible region RV and the direct incident width D L1 (=round trip width W) has been described as a representative example. However, even if this is not the case, the optical member 1 may be configured such that the switching mirror 3 is not disposed in the area of ​​the visible region RV from which light is emitted for the number of round trips (N-1). For example, the optical member 1 may be configured such that the direct incident width D L1 Even if there are m regions R1 to Rm of the switching mirror 3 in the visible region RV, as long as the switching mirror 3 is not disposed in the region RVN at the end of the visible region RV, the effect of simplifying the dimming control can be obtained as described above.

[0057] According to this embodiment, in addition to the same effects as those of the first embodiment, the switching mirror 3 is not arranged in the Nth region RVN of the viewing region RV, which is the farthest from the incident end 3A, and therefore the optical element 1 has simpler dimming control than the first embodiment and also has the effect of being more compact.

[0058] (Third embodiment) An optical member 1 according to the third embodiment will be described below. Fig. 15 shows a cross section corresponding to Fig. 1, and also shows a simplified version of the mirror 2 and the switching mirror 3 for ease of viewing.

[0059] 15, the optical member 1 of this embodiment differs from the first embodiment in that it further includes a light guide body 6 to which a mirror 2 and a switching mirror 3 are attached. This difference will be mainly described in this embodiment.

[0060] The light guide 6 is made of any light-transmitting material, such as a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, or acrylic, or glass. In this embodiment, the light guide 6 is separate from the mirror 2 and the switching mirror 3, and the mirror 2 and the switching mirror 3 are attached to the light guide 6 using, for example, an optical adhesive such as OCA (not shown). As shown in FIG. 15 , the light guide 6 has a first surface 6a, which is a smooth surface, and a second surface 6b, which is a smooth surface parallel to the first surface 6a. For example, the light guide 6 has the mirror 2 bonded to a portion of the first surface 6a and the switching mirror 3 bonded to a portion of the second surface 6b. A predetermined region of the first surface 6a of the light guide 6 is exposed from one end of the mirror 2, and this exposed region serves as an incident portion 6aa through which external light L1 enters the interior. A predetermined area of ​​the second surface 6b of the light guide 6 from the end opposite to the incident portion 6aa is exposed from the switching mirror 3, and this exposed area serves as an emission portion 6ba that emits the incident light L2 to the outside without passing through the switching mirror 3. Note that the light guide 6 only needs to have the parallel first surface 6a and second surface 6b, and the shapes of other portions may be changed as appropriate within the range that does not interfere with the guiding of the incident light L2 inside.

[0061] As shown in FIG. 15, the width of the incident portion 6aa in the light guiding direction D2 is Di, and the distance in the thickness direction D1 between the first surface 6a and the second surface 6b of the light guide 6 is T, where Di = T(tan θ1 + tan φ1). In other words, the width Di of the incident portion 6aa corresponds to the round-trip width W in the first and second embodiments. As shown in FIG. 16, θ1 is the angle of incidence on the switching mirror 3 of incident light L2, which is obtained by refracting external light L1 incident on the incident portion 6aa at an incident angle θ inside the light guide 6, which has a refractive index of n. φ1 is the angle of reflection of the incident light L2, which is reflected by the switching mirror 3 in the reflective state, at the incident angle θ1, and is greater than θ1. For example, the first surface 6a has a width Di from one end as the incident portion 6aa, and the entire remaining area is covered by the mirror 2.

[0062] The emission section 6ba is a region that emits the incident light L2 that has made X round trips between the mirror 2 and the switching mirror 3 to the outside without passing through the switching mirror 3. For example, the width of the emission section 6ba in the light guide direction D2 is Do, where Do≦Di.

[0063] As in the second embodiment, the switching mirror 3 is divided into a plurality of regions R1 to R(N-1) corresponding to regions excluding the last region RVN among the regions RV1 to RVN that constitute the visible region RV of the optical member 1. As in the second embodiment, the optical member 1 is configured such that the switching mirror 3 is not arranged in the Nth region RVN, and the emission portion 6ba of the light guide 6 corresponds to the Nth region RVN.

[0064] In this embodiment, the mirror 2 and the switching mirror 3 have the same refractive index as the light guide 6. As a result, in the optical member 1, the incident light L2 that enters the light guide 6 is not reflected at the interface between the light guide 6 and the mirror 2 or the switching mirror 3, and noise caused by the reflected light at the interface is suppressed.

[0065] According to this embodiment, in addition to the same effects as those of the second embodiment, the mirror 2 and the switching mirror 3 are arranged on the parallel first surface 6a and second surface 6b of the light guide 6, respectively, so that the optical element 1 can also obtain the effect of stably ensuring the parallel state of this pair of mirrors.

[0066] Although the optical member 1 has been described above as having a structure in which the mirror 2 and the switching mirror 3 are attached to the light guide 6 with an optical adhesive (not shown), the present invention is not limited thereto. For example, as shown in FIG. 17 , the mirror 2 may be configured by using the light guide 6 as a support substrate for the first reflective layer 22 instead of the transparent substrate 21, and including the light guide 6, the first reflective layer 22, and the light-shielding substrate 23. As shown in FIG. 18 , the switching mirror 3 may be configured by using the light guide 6 as a support substrate for the second reflective layer 33 instead of the first transparent substrate 31, and including a first transparent electrode 32, a second reflective layer 33, a second transparent electrode 34, and a second transparent substrate 35 stacked on the light guide 6. In other words, the mirror 2 and the switching mirror 3 may be manufactured separately from the light guide 6 and attached to the light guide 6, or may be formed directly on the first surface 6 a and the second surface 6 b of the light guide 6. Furthermore, the optical member 1 may have an anti-reflection layer formed on the exit portion 6ba to prevent external light from the second surface 6b from being reflected on the second surface 6b and generating noise. Furthermore, although the above describes an example in which the switching mirror 3 is not disposed in the end region of the second surface 6b, the present invention is not limited to this, and the optical member 1 may have the switching mirror 3 disposed over the entire second surface 6b.

[0067] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one, or less than one, are also within the scope and spirit of the present disclosure.

[0068] The control unit (e.g., circuit board 5) and methods described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and methods described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and methods described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0069] It goes without saying that in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of the components of the embodiments are mentioned, they are not limited to the specific numbers unless they are specifically stated as essential or are clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., unless they are specifically stated or are clearly limited to a specific shape, positional relationship, etc. in principle.

[0070] (Aspects of the present disclosure) The present disclosure described above can be understood from the following viewpoints, for example. [First viewpoint] An optical element, a mirror (2) having a first reflective layer (22) that reflects light; a switching mirror (3) having a second reflective layer (33) that can be switched between a transparent state that transmits light and a reflective state that reflects light, and that is arranged in parallel with the mirror; a thickness direction (D1) is a normal direction to a plane formed by the mirror or the switching mirror, an incident angle is an angle formed between the traveling direction of incident light incident on the mirror or the switching mirror and the thickness direction, and a reflection angle is an angle formed between the traveling direction of reflected light reflected by the mirror or the switching mirror and the thickness direction, the first reflective layer has a first inclined surface inclined with respect to a plane of the mirror, and an axis along a normal direction to the first inclined surface is a first tilt axis (ax1); the second reflective layer has a second inclined surface inclined with respect to a plane formed by the switching mirror, and an axis along a normal direction to the second inclined surface is a second inclination axis (ax2); The switching mirror reflects the reflected light at a reflection angle φ greater than θ when the incident angle of the incident light is θ, The mirror is an optical element in which the first tilt axis is parallel to the second tilt axis, thereby reflecting incident light having an incident angle φ at a reflection angle θ. [Second perspective] The optical member according to the first aspect, wherein the second reflective layer is made of a cholesteric liquid crystal. [Third Perspective] The optical member according to the first or second aspect, wherein the first reflective layer is made of a cholesteric liquid crystal. [Fourth viewpoint] The optical member according to any one of the first to third aspects, wherein the mirror has an anti-reflection layer (24) on one surface (2a) facing the switching mirror. [Fifth viewpoint] The optical member according to any one of the first to fourth aspects, wherein the switching mirror has an anti-reflection layer (36) on a surface (3a) facing the mirror. [Sixth viewpoint] The switching mirror is divided into a plurality of regions (R1 to RN), The optical element according to any one of the first to fifth aspects, wherein one of the plurality of regions of the second reflective layer is sequentially switched to a transparent state, and the remaining regions other than the one region that is switched to the transparent state are switched to a reflective state. [Seventh viewpoint] An area where the switching mirror or light passing through the mirror is emitted and allows a user to view an outside scene is defined as a visible area (RV), and an end of the switching mirror where outside scene light is incident is defined as an incident end (3A), The visible area is divided into N areas (RV1 to RVN), The optical member according to any one of the first to fifth aspects, wherein the switching mirror is not disposed in an Nth region (RVN) that is an Nth region counting from the incident end of the viewing region. [Eighth viewpoint] The optical fiber further includes a light guide (6) made of a light-transmitting material and having a first surface (6a) and a second surface (6b) parallel to the first surface, the mirror is disposed on the first surface; The optical member according to any one of the first to seventh aspects, wherein the switching mirror is disposed on the second surface. [Explanation of symbols]

[0071] 2...mirror, 2a...one surface, 22...first reflective layer, 24...anti-reflective layer, 3...switching mirror, 3a...opposite surface, 3A...incident end portion, 33...second reflective layer, 36...anti-reflective layer, 6...light guide, 6a...first surface, 6b...second surface, D1...thickness direction, R1 to RN...divided area (of switching mirror), RV...visible area, RV1 to RVN...divided area (of visible area)

Claims

1. An optical element, a mirror (2) having a first reflective layer (22) that reflects light; a switching mirror (3) having a second reflective layer (33) that can be switched between a transparent state that transmits light and a reflective state that reflects light, and that is arranged in parallel with the mirror; a thickness direction (D1) is a normal direction to a plane formed by the mirror or the switching mirror, an incident angle is an angle formed between the traveling direction of incident light incident on the mirror or the switching mirror and the thickness direction, and a reflection angle is an angle formed between the traveling direction of reflected light reflected by the mirror or the switching mirror and the thickness direction, the first reflective layer has a first inclined surface inclined with respect to a plane of the mirror, and an axis along a normal direction to the first inclined surface is a first tilt axis (ax1); the second reflective layer has a second inclined surface inclined with respect to a plane formed by the switching mirror, and an axis along a normal direction to the second inclined surface is a second tilt axis (ax2); The switching mirror reflects the reflected light at a reflection angle φ greater than θ when the incident angle of the incident light is θ, The mirror is an optical element in which the first tilt axis is parallel to the second tilt axis, thereby reflecting incident light having an incident angle φ at a reflection angle θ.

2. The optical member according to claim 1 , wherein the second reflective layer is made of a cholesteric liquid crystal.

3. The optical member according to claim 1 , wherein the first reflective layer is made of a cholesteric liquid crystal.

4. The optical element according to claim 2, wherein the mirror has an anti-reflection layer (24) on one surface (2a) facing the switching mirror.

5. The optical element according to claim 3, wherein the switching mirror has an anti-reflection layer (36) on a surface (3a) facing the mirror.

6. The switching mirror is divided into a plurality of regions (R1 to RN), The optical element according to claim 1 , wherein one of the plurality of regions of the second reflective layer is sequentially switched to a transparent state, and the remaining regions other than the one region that is switched to the transparent state are switched to a reflective state.

7. An area where the switching mirror or light passing through the mirror is emitted and allows a user to view an outside scene is defined as a visible area (RV), and an end of the switching mirror where outside scene light is incident is defined as an incident end (3A), The visual recognition area is divided into N areas (RV1 to RVN), The optical member according to claim 1 , wherein the switching mirror is not disposed in an Nth region (RVN) of the visual recognition region that is the Nth region farthest from the incident end.

8. The optical fiber further includes a light guide (6) made of a light-transmitting material and having a first surface (6a) and a second surface (6b) parallel to the first surface, the mirror is disposed on the first surface; The optical member according to claim 1 , wherein the switching mirror is disposed on the second surface.

Images