Optical member
The optical member with a light guide holder and transparent covers effectively prevents visibility reduction by keeping the exit surface clean and redirecting unintended reflections, addressing the challenge of adhering water droplets and dust on the exit surface.
Patent Information
- Application Number
- JP2024027638
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-27
- Publication Date
- 2025-09-08
AI Technical Summary
Existing optical elements with a half-mirrorless structure are prone to visibility reduction due to water droplets or dust adhering to the exit surface, which scatter emitted light and are difficult to clean, especially at flat portions with adjacent prism portions.
An optical member with a light guide covered by a light guide holder and transparent covers at the entrance and exit surfaces, preventing water droplets and dust from adhering directly to the exit surface, and facilitating easy cleaning by using transparent covers that cover the entrance and exit surfaces.
Prevents visibility reduction by keeping the exit surface clean and reducing ghost images through angled transparent covers that redirect unintended reflections, maintaining clear visibility in blind spots.
Smart Images
Figure 2025130462000001_ABST
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to an optical member using a light guide that internally reflects a portion of light incident from an incident surface and emits the incident light and its reflected light to the outside from a surface different from the incident surface. [Background technology]
[0002] Conventionally, this type of optical member is, for example, attached to a light blocking body, and serves as a blind spot assistance device that allows external light from a blind spot area created by the light blocking body to enter the inside, reflect the external light inside, and emit the external light from a surface different from the surface through which the external light enters, thereby allowing the blind spot area to be viewed. An example of such an optical member is described in Patent Document 1.
[0003] The optical element described in Patent Document 1 is composed of a translucent light guide, and a portion of external light incident on the incident surface of the light guide is guided by total reflection inside and emitted to the outside from an emission section different from the incident surface, allowing a user standing on the emission surface side to see the outside scene in a blind spot. This results in a half-mirrorless structure that does not require a half-mirror made of a reflective material different from the light guide on the emission section side, reducing loss due to absorption of external light when guided inside the light guide and variation in brightness due to wavelength. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Japanese Patent Publication No. 2023-028532 Summary of the Invention [Problem to be solved by the invention]
[0005] When water droplets or dust adhere to the exit surface of the optical element described in Patent Document 1, the adhered water droplets or dust scatter part of the emitted light, reducing the visibility of the scene in the blind spot. Also, since this optical element has a structure in which the exit surface of the light guide is made up of flat portions that are flat surfaces and prism portions that are triangular prism-shaped protrusions arranged alternately, when water droplets or the like adhere to the exit surface, the flat portions are difficult to wipe due to the adjacent prism portions, and some may not be wiped clean.
[0006] In view of the above, an object of the present disclosure is to provide an optical element that uses a light guide with a half-mirrorless structure and can suppress a decrease in visibility caused by water droplets or the like adhering to the exit surface. [Means for solving the problem]
[0007] According to one aspect of the present disclosure, an optical member includes: a light guide (2) made of a translucent material, the light guide (2) having an incident surface (2a, 21a) that allows external scene light (L1) to enter the interior, an exit surface (2b) that is made up of a plurality of protruding prism portions (21) that emit a portion of the incident light (L2) that has entered from the incident surface to the outside and a plurality of flat portions (22) that reflect a portion of the incident light by total reflection, and a reflecting surface (2c) that reflects the light reflected by the flat portions toward the exit surface; a light guide holder (3) that holds the light guide, the light guide holder having a first opening (33) that exposes the incident surface of the light guide and a second opening (34) that exposes the exit surface of the light guide; a first transparent cover (4) made of a light-transmitting material, attached to the first opening, and covering the incident surface; and a second transparent cover (5) made of a light-transmitting material, attached to the second opening, and covering the exit surface.
[0008] This optical element has a light guide with a half-mirrorless structure held by a light guide holder, and the entrance surface is exposed from the light guide holder at a first opening and the exit surface at a second opening, with the entrance surface covered by a first transparent cover and the exit surface covered by a second transparent cover. This prevents water droplets and the like from adhering to the exit surface, and because water droplets and the like adhere to the transparent cover that covers the exit surface instead of the exit surface, the optical element has a structure that makes it easy to wipe, and it is possible to prevent a decrease in visibility caused by water droplets and the like adhering to the exit surface.
[0009] 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]
[0010] [Figure 1] FIG. 1 is a perspective view showing an optical member according to a first embodiment. [Figure 2] 2 is a diagram corresponding to the cross-sectional view taken along line II-II in FIG. 1, and is an explanatory diagram of light guide by an optical member. FIG. [Figure 3] FIG. 2 is an exploded perspective view of the optical member according to the first embodiment. [Figure 4] FIG. 10 is a perspective view showing an optical member according to a second embodiment. [Figure 5] 5 is a diagram corresponding to the cross-sectional view taken along line VV in FIG. 4, and is an explanatory diagram illustrating the effect of the louver in suppressing the incidence of external light on the second transparent cover. [Figure 6] 10A and 10B are explanatory diagrams illustrating the inclination of the louvers in the optical member according to the second embodiment. [Figure 7] 10 is an explanatory diagram of the length of the louver in the optical member according to the second embodiment. FIG. [Figure 8] FIG. 3 is a cross-sectional view corresponding to FIG. 2 and showing an optical member according to a third embodiment. [Figure 9] FIG. 10 is a cross-sectional view corresponding to FIG. 2 and showing an optical member according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0011] 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.
[0012] (First embodiment) An optical member 1 according to a first embodiment will now be described. The optical member 1 according to this embodiment is attached to, for example, a member or obstacle that blocks a user's field of view and creates a blind spot, and is used as a blind spot assistance device that allows the user to view the scene in the blind spot. For example, as shown in FIG. 1 , in the case of an in-vehicle application, the optical member 1 is attached to a predetermined light blocking body or a cover body thereof, such as a pillar of the vehicle on which it is mounted, and guides external light from the blind spot area caused by the light blocking body to the user's side, allowing the user to view the scene in the blind spot area.
[0013] In Fig. 1, the outer casing of the light guide 2, which will be described later, is shown by a dashed line, and a light guide holder 3 that holds the light guide 2 and transparent covers 4 and 5 that cover part of the light guide 2 are shown by solid lines. In Fig. 3, the parts of the outer casing of the light guide 2 that are not directly visible from the angle shown in Fig. 3 are shown by dashed lines.
[0014] 1, the optical member 1 of this embodiment includes a light guide 2, a light guide holder 3, and transparent covers 4 and 5. For example, the optical member 1 has the light guide holder 3 that holds the light guide 2 attached to a pillar cover 10 or the like, and guides light from a blind spot caused by a light blocking body inside the light guide 2 and emits the light toward the user, allowing the user to view the scene in the blind spot.
[0015] As shown in FIGS. 2 and 3, the light guide 2 includes an incident surface 2a, an exit surface 2b, a reflecting surface 2c, a terminal surface 2d, an upper surface 2e, and a lower surface 2f. The light guide 2 is primarily made of a light-transmitting material, and has a half-mirrorless structure without a half-mirror made of a reflective material different from the light-transmitting material. Examples of light-transmitting materials include resin materials such as polyethylene terephthalate, polycarbonate, polyethylene, and acrylic, as well as inorganic materials such as glass. The light guide 2 is designed to guide light entering the interior through the incident surface 2a by total reflection at a portion of the exit surface 2b and the reflecting surface 2c, while emitting another portion of the incident light from a portion of the exit surface 2b. Because the light guide 2 has many features in common with the light guide 2 described in Patent Document 1, this specification will mainly describe its distinctive features.
[0016] 2, for convenience of explanation, external light incident on the incident surface 2a will be referred to as "external scene light L1," light that enters the light guide 2 from the incident surface 2a will be referred to as "incident light L2," and light of the incident light L2 that is emitted to the outside from the emission surface 2b will be referred to as "emitted light L3." Furthermore, the angle between the traveling direction of the external scene light L1 or the incident light L2 and the normal direction (hereinafter simply referred to as "normal direction") to the plane formed by the reflecting surface 2c or a flat portion 22 described below will sometimes be referred to as the "incident angle."
[0017] The incident surface 2a is a surface that allows external scene light L1 from a blind spot area caused by a light blocking body (not shown) to enter the light guide 2. The incident surface 2a is a flat surface that connects the exit surface 2b and the reflecting surface 2c, and is inclined at a predetermined acute angle with respect to the plane formed by the reflecting surface 2c so that the incident angle φ of the incident light L2 is larger than the incident angle of the external scene light L1. When the light guide 2 is held by the light guide holder 3, the incident surface 2a is located at a first opening 33 (described later) and is covered by a first transparent cover 4.
[0018] The exit surface 2b is the first area where the incident light L2 from the incident surface 2a reaches, and reflects a portion of the incident light L2 toward the reflecting surface 2c while emitting another portion of the incident light L2 to the outside. The exit surface 2b is made up of, for example, a plurality of protruding exit prism portions 21 and a plurality of flat portions 22, which are flat surfaces, arranged alternately and repeatedly.
[0019] The plurality of exit prism portions 21 each have an exit portion 21a, which is a surface that exits the incident light L2 to the outside, and an adjacent surface 21b adjacent to the exit portion 21a. The plurality of exit prism portions 21 are, for example, triangular prism-shaped, and are arranged parallel with the same extension direction. The exit portion 21a is, for example, a flat surface that is approximately parallel to the incident surface 2a. "Approximately parallel" does not only mean completely parallel, but also includes cases where the surfaces are not completely parallel due to unavoidable factors such as processing errors, but can be considered to be nearly parallel. The adjacent surface 21b is a non-optical surface that is not used to reflect or exit the incident light L2, and may have a light-shielding film (not shown) formed on it.
[0020] The flat portions 22 are, for example, flat surfaces located on the same plane and function as first reflecting surfaces that reflect the incident light L2 toward the reflecting surface 2c by total reflection. When the light guide 2 is held by the light guide holder 3, the exit surface 2b is located at a second opening 34 (described later) and is covered by the second transparent cover 5.
[0021] The light guide 2 is designed to satisfy the total reflection condition of the following equation (1) when the refractive index of the constituent material is n, the external medium is air (refractive index = 1), and the incident angle of the incident light L2 to the flat portion 22 and the reflecting surface 2c is φ, making it possible to guide light in a mirrorless structure.
[0022] sinφ≧1 / n (1) For ease of explanation, the direction perpendicular to the extension direction of the emission prism portions 21 and along the arrangement direction of the plurality of emission prism portions 21 will be referred to as the "first direction D1," and the direction along the normal direction will be referred to as the "second direction D2." The direction along the extension direction of the emission prism portions 21 will be referred to as the "third direction D3." The direction from the incident surface 2a toward the terminal surface 2d of the first direction D1 is the direction in which the incident light L2 is guided, and can also be referred to as the light guide direction. The second direction D2 corresponds to the thickness direction of the light guide body 2.
[0023] The reflecting surface 2c is a second reflecting surface that faces the exit surface 2b in the second direction D2 and reflects the light of the incident light L2 that is reflected by the flat portion 22 toward the exit surface 2b by total reflection. The reflecting surface 2c functions as a pair of mirrors together with the flat portion 22 of the exit surface 2b, and is, for example, a flat surface that is approximately parallel to the flat portion 22.
[0024] The terminal surface 2d is located, for example, on the opposite side of the incident surface 2a in the first direction D1, and is the surface where part of the incident light L2 finally reaches. The terminal surface 2d is a flat surface connecting the flat portion 22 and the reflecting surface 2c, as shown in Figures 2 and 3, for example, but is not limited to this. The terminal surface 2d may form a single plane together with the exit portion 21a of the exit prism portion 21, or may have any surface shape.
[0025] The upper surface 2e and the lower surface 2f are located at both ends of the light guide 2 in the third direction D3, and are non-optical surfaces that are not used for guiding, i.e., reflecting, the incident light L2 inside the light guide 2. The upper surface 2e and the lower surface 2f are, for example, single flat surfaces that connect the incident surface 2a, the exit surface 2b, the reflecting surface 2c, and the terminal surface 2d, and are arranged in parallel, but may have any shape as long as they do not interfere with the guiding of the incident light L2.
[0026] As shown in FIG. 3 , the light guide holder 3 includes a holder portion 31 for holding the light guide 2 and a rod-shaped body 32 attached to the holder portion 31. The light guide holder 3 can be fixed to the light shielding body by any method, such as by having a holding portion (not shown) on the holder portion 31 for attaching it to a pillar cover 10 or the like, or by being fixed to the light shielding body or its cover with a fastening member such as a screw. The light guide holder 3 is made of any material, such as a resin material, and at least the portion facing the light guide 2 is made of a light-blocking material such as black paint or a light-blocking material that absorbs visible light. This prevents unintended light from entering the light guide 2 and exiting from the exit surface 2b, thereby preventing ghost images. The light guide holder 3 may be entirely made of any light-blocking material.
[0027] The holder 31 includes, for example, a substantially U-shaped frame 311 facing the end surface 2d, upper surface 2e, and lower surface 2f of the light guide 2, which are not used to reflect the incident light L2, and a ceiling 312 covering the reflecting surface 2c. For example, the thickness of the frame 311 is greater than the thickness of the light guide 2 in the second direction D2, and grooves (not shown) are formed on the surface of the frame 311 facing the light guide 2 to fit into the end surface 2d, upper surface 2e, and lower surface 2f. This allows the holder 31 to hold the light guide 2 by sliding the light guide 2 into the grooves (not shown) along the direction indicated by the white arrow in FIG. 3 and fitting the grooves. The ceiling 312 is positioned at a gap from the reflecting surface 2c of the light guide 2, for example, to create an air layer between the reflecting surface 2c of the light guide 2 and the ceiling 312, preventing interference with total reflection of the incident light L2. For example, the holder 31 has a tip 313, which is a tip of a portion of the frame 311 facing the upper surface 2 e and the lower surface 2 f on the side of the incident surface 2 a in the first direction D1, and the rod-shaped body 32 is attached to the tip 313. The light guide holder 3 has a structure having two openings formed by the holder 31 and the rod-shaped body 32, namely, a first opening 33 that exposes the incident surface 2 a of the light guide 2 and a second opening 34 that exposes the exit surface 2 b.
[0028] The rod-shaped body 32 is a member that is attached to the frame body 311 so as to connect the two tip ends 313 of the frame body 311 after the light guide 2 is inserted into and held in the holder 31, for example, and prevents the light guide 2 from coming off the holder 31. The rod-shaped body 32 is attached to the tip ends 313 by any fixing means, for example, a fastening member such as a screw (not shown), but from the viewpoint of maintenance, it is preferable that the rod-shaped body 32 be attached by a detachable fixing means. For example, one end of the transparent covers 4, 5 is attached to the rod-shaped body 32, and the rod-shaped body 32 also serves as a support for the transparent covers 4, 5.
[0029] The first transparent cover 4 is a plate-shaped light-transmitting member attached to the first opening 33 of the light guide holder 3 so as to cover the entire incident surface 2a. In other words, the first transparent cover 4 is a light-transmitting member that prevents foreign matter such as water droplets and dust from adhering to the incident surface 2a of the light guide 2 while not interfering with the incidence of external light L1. The first transparent cover 4 is attached to the tip 313 and the rod-shaped body 32 by any fastening means (not shown), such as a screw or nail structure (not shown). However, from the viewpoint of maintenance, it is preferable to attach it by a detachable fastening means. The first transparent cover 4 is made of, for example, a light-transmitting resin material or inorganic material, similar to the light guide 2. The first transparent cover 4 has, for example, a light transmittance of 60% or more in the visible light region with wavelengths of 450 nm to 750 nm.
[0030] The first transparent cover 4 has a predetermined rigidity and strength, and a thickness of 0.25 mm or more so that water droplets, dust, and the like adhering to the surface can be wiped off. As shown in FIG. 2, the first transparent cover 4 is flat and not parallel to the plane of the incident surface 2a. The first transparent cover 4 is attached so that the angle θ1 with respect to the plane satisfies θ1≧3°. This allows light from the outside scene L1 reflected from the incident surface 2a of the light guide 2 to be reflected from the surface of the first transparent cover 4 facing the incident surface 2a. Even if the light enters the interior through the incident surface 2a, the light is emitted in a direction different from the emitted light L3, thereby suppressing the occurrence of ghost images.
[0031] The second transparent cover 5 is attached to the light guide holder 3 so as to cover the second opening 34 and is a plate-shaped light-transmitting member that covers the entire area of the light-emitting surface 2b. Similar to the first transparent cover 4, the second transparent cover 5 is made of any light-transmitting material, has a visible light transmittance of 60% or more, and a thickness of 0.25 mm or more. The second transparent cover 5 is a light-transmitting member that transmits light L3 emitted from the light-emitting surface 2b while preventing foreign matter such as water droplets from adhering to the light-emitting surface 2b of the light guide 2. Similarly to the first transparent cover 4, the second transparent cover 5 is attached to the holder 31 and the rod-shaped body 32 by any detachable fastening means. As shown in FIG. 2, the second transparent cover 5 is flat and not parallel to the plane formed by the flat portions 22. The second transparent cover 5 is attached so that the angle θ2 formed with the plane satisfies θ2≧3°. As a result, the emitted light L3 is surface-reflected on the surface of the second transparent cover 5 on the side of the emission surface 2b, and even if the light is surface-reflected on the flat portion 22, it travels in a different direction from the emitted light L3, thereby suppressing the occurrence of ghost images.
[0032] The transparent covers 4 and 5 are not limited to a flat plate shape as long as the outer surface opposite the light guide 2 is easily wiped clean, and may be partially or entirely curved in shape.
[0033] The above is the basic configuration of the optical member 1 of this embodiment.
[0034] According to this embodiment, the optical member 1 has a nearly sealed structure in which the light guide 2 having a half-mirrorless structure is covered by the light guide holder 3 and the transparent covers 4 and 5, and prevents foreign matter such as water droplets from directly adhering to the light guide 2. This optical member 1 has a structure in which foreign matter adheres to the transparent covers 4 and 5 that cover the entrance surface 2a and exit surface 2b of the light guide 2, instead of to the entrance surface 2a and exit surface 2b of the light guide 2, making it easy to wipe off foreign matter and preventing a decrease in visibility due to the adhesion of foreign matter. This optical member 1 also has the following effects.
[0035] (1) The optical member 1 is held by the light guide holder 3 with the first transparent cover 4 tilted at an angle of 3° or more with respect to the incident surface 2a of the light guide 2, and the second transparent cover 5 tilted at an angle of 3° or more with respect to the plane of the flat portion 22. As a result, even if light is reflected from the surface between the first transparent cover 4 and the incident surface 2a of the light guide 2, the unintended surface-reflected light is emitted in a direction different from the emitted light L3, compared to when the first transparent cover 4 and the incident surface 2a of the light guide 2 are parallel and the second transparent cover 5 and the flat portion 22 of the light guide 2 are parallel. This suppresses the generation of ghost images by the transparent covers 4 and 5.
[0036] (2) In the optical member 1, the transparent covers 4 and 5 have a transmittance of 60% or more for light in the visible light region with wavelengths of 450 nm to 750 nm and a thickness of 0.25 mm or more. This reduces the loss of visible light through the transparent covers 4 and 5, while ensuring the rigidity and strength of the transparent covers 4 and 5, making them easy to wipe clean.
[0037] (Second embodiment) An optical member 1 according to the second embodiment will be described.
[0038] 4, the optical member 1 of this embodiment differs from that of the first embodiment in that the light guide holder 3 has a louver 321. This difference will be mainly described in this embodiment.
[0039] The light guide holder 3 includes, for example, a rod-shaped body 32 having a louver 321. As shown in FIG. 5, the louver 321 is a member that prevents external light L4 from penetrating into a predetermined area of the outer surface 5a of the second transparent cover 5, which covers the exit surface 2b, including the end portion of the second transparent cover 5 on the side of the entrance surface 2a. The outer surface 5a is the surface of the second transparent cover 5 opposite the light guide 2. Without the louver 321, for example, as indicated by the dashed arrow in FIG. 5, the external light L4 would be surface-reflected by the outer surface 5a of the second transparent cover 5, and this surface-reflected light L5, together with the exit light L3, could reach the iris ELP, i.e., the user's eyes. In this case, the user would see a scene formed by the reflected light of the exit light L3 and the external light L4, reducing the visibility of the scene in the blind spot caused by the exit light L3. In this way, the louver 321 is a member that ensures visibility of the scene in the blind spot by suppressing surface reflection of external light L4 in a predetermined area on the outer surface 5a of the second transparent cover 5. The louver 321 is, for example, configured as part of the rod-shaped body 32 and has a flat plate shape. The louver 321 is, for example, configured from any material with light-blocking properties, and has a transmittance of 1% or less for visible light in the wavelength range of 450 nm to 750 nm.
[0040] The iris ELP is an elliptical eye range that statistically represents the eye position distribution of the driver of a vehicle equipped with the optical member 1, and is specified, for example, in the Japanese Industrial Standard JISD0021:1998. For example, the 95th percentile iris is used as the iris ELP, but the present invention is not limited to this, and a 90th percentile iris or a 99th percentile iris may also be used. In the two ellipses of the iris ELP shown in Figures 5 to 7, for example, the upper one corresponds to the right eye and the lower one corresponds to the left eye.
[0041] For ease of explanation, as shown in FIG. 6 , the plane of the flat portion 22 is referred to as the “reference plane P1,” and the normal direction to the reference plane P1 is referred to as the “reference normal direction D4.” The angle between the imaginary line VL1 at the center of the thickness of the louver 321 and the reference normal direction D4 is referred to as the “louver inclination angle θr1.” When the louver 321 has a flat plate shape, the imaginary line VL1 can also be considered as an imaginary line along the extension direction of the louver 321. Furthermore, when one of the exit prism portions 21 is disposed at the center of the exit surface 2b of the light guide 2 in the first direction D1, the center of the exit portion 21a of the exit prism portion 21 is referred to as the “exit center C1.” When the width of the exit surface 2b in the first direction D1 is Lw, the exit center C1 is located at a distance Lw / 2 from the end of the exit surface 2b. Furthermore, the center of the iris ELP of the vehicle to which the optical element 1 is attached is referred to as the "iris center C2," and the angle between the virtual line VL2 obtained by connecting the exit center C1 and the iris center C2 with a straight line and the reference normal direction D4 is referred to as the "angle θw."
[0042] Louver 321 is designed so that angle θw and louver inclination angle θr1 satisfy the following formula (2).
[0043] θr1-15°≦θw≦θr1+15°···(2) If the louver 321 is designed so that θr1-15°<θw, for example, when the optical element 1 is attached to an A-pillar of a vehicle, the louver 321 will overlap a portion of the windshield, creating a new blind spot due to the louver 321 itself. On the other hand, if the louver 321 is designed so that θw<θr1+15°, the louver 321 itself will block the light L3 emitted from a portion of the exit surface 2b on the entrance surface 2a side, preventing the user from seeing part of the scene in the blind spot. Therefore, by designing the louver 321 to satisfy the above formula (2), the optical element 1 has a structure that suppresses a decrease in visibility due to external light L4 entering the second transparent cover 5, while preventing the louver 321 itself from causing a decrease in visibility.
[0044] 7, the length of louver 321 from a plane along the outer surface 5a of flat second transparent cover 5 to the tip is defined as louver length Lr, and the angle between this plane and an imaginary line VL1 along the center of the thickness of louver 321 is defined as θr2. In this case, louver 321 is designed to satisfy, for example, the following formula (3).
[0045] Lr·sinθr2≧Lg·sinθx···(3) As shown in FIG. 7, Lg in equation (3) is the length of an imaginary line VL3 extending from the end 5aa of the second transparent cover 5 toward the louver 321, with the end 5aa being the end of the outer surface 5a of the second transparent cover 5 on the end surface 2d side. The imaginary line VL3 corresponds to an imaginary line VL4 obtained by connecting the end 5aa of the second transparent cover 5 to a point PL located at the left end of the iris ELP of the vehicle to which the optical member 1 is attached, and the imaginary line VL4 is assumed to be specularly reflected by the outer surface 5a. The angle θx is the angle between the imaginary line VL3 and the outer surface 5a, as shown in FIG. 7. When the louver 321 satisfies equation (3), the external light L4 that is specularly reflected by the second transparent cover 5 and reaches the iris ELP is completely blocked by the louver 321, thereby preventing the generation of ghost images due to the external light L4. In other words, the louver 321 is designed to have a length Lr that blocks all of the external light L4 that is specularly reflected by the second transparent cover 5 and reaches the iris ELP. In other words, the length Lr of the louver 321 is designed so that virtual light along a virtual straight line VL4 obtained by connecting the left end PL of the iris ELP and the terminal end 5aa of the second transparent cover 5 intersects with a virtual light ray specularly reflected by the outer surface 5a. Regarding the above equation (3), while the optical element 1 is attached to the right of the left and right A-pillars of a vehicle as a representative example, this is not limiting. For example, if the optical element 1 is attached to the left A-pillar of a vehicle, the louver length Lr of the louver 321 may be designed in the same manner as equation (3), assuming a virtual straight line connecting the right end and the terminal end 5aa of the iris ELP instead of the left end PL.
[0046] According to this embodiment, in addition to the same effects as those of the first embodiment, the optical member 1 has the louver 321, which also provides the effect of suppressing the generation of ghost images caused by external light L4 entering the second transparent cover 5. Furthermore, the optical member 1 also provides the following effects.
[0047] (1) The optical member 1 is designed so that the relationship between the louver tilt angle θr1 and the angle θw is θr1-15°≦θw≦θr1+15°. This has the effect of preventing the louver 321 from creating a new blind spot and preventing the louver 321 from blocking the emitted light L3.
[0048] (2) In the optical member 1, the length Lr of the louver 321 is equal to or greater than the length at which virtual light along the virtual straight line VL5 obtained by connecting the left end PL of the iris ELP and the terminal end 5aa of the second transparent cover 5 intersects with a virtual light ray specularly reflected by the outer surface 5a. As a result, the louver 321 blocks external light L4 that may reach the iris ELP if specularly reflected by the outer surface 5a of the second transparent cover 5, thereby suppressing the occurrence of ghost images caused by the external light L4.
[0049] (3) In the optical member 1, the louver 321 has a transmittance of 1% or less for light in the visible light region with wavelengths of 450 nm to 750 nm. As a result, the louver 321 reliably blocks external light L4 from reaching a portion of the second transparent cover 5, and suppresses the occurrence of ghost images due to surface-reflected light on the outer surface 5a of the second transparent cover 5.
[0050] (Third embodiment) An optical member 1 according to the third embodiment will be described.
[0051] 8, the optical member 1 of this embodiment differs from the first embodiment in that the outer surface 5a of the second transparent cover 5 is a reflection suppressing portion 51 that suppresses reflection of light. This difference will be mainly described in this embodiment.
[0052] In this embodiment, the second transparent cover 5 has a reflection suppression section 51 on the side opposite to the light guide 2. The reflection suppression section 51 may be formed directly on the base material of the second transparent cover 5, or may be made of a film that is separate from the base material and attached to it. The reflection suppression section 51 has, for example, a known anti-reflection layer or a moth-eye structure, and is configured to scatter the surface-reflected light or superimpose light that is in the opposite phase to the surface-reflected light, thereby reducing the amount of surface-reflected light when external light L4 is incident on the second transparent cover 5.
[0053] According to this embodiment, in addition to the effects of the first embodiment, the optical member 1 can also obtain the effect of suppressing the occurrence of ghost images caused by the incidence of external light L4 on the second transparent cover 5 without having the louver 321.
[0054] (Fourth embodiment) An optical member 1 according to the fourth embodiment will be described.
[0055] 9, the optical member 1 of this embodiment differs from the first embodiment in that the shapes of the light guide 2, the light guide holder 3, and the first transparent cover 4 are changed. In this embodiment, this difference will be mainly described.
[0056] In this embodiment, the light guide 2 has an incident portion 2g adjacent to the reflecting surface 2c and facing the exit surface 2b, instead of the incident surface 2a, which allows external light L1 to enter the interior. The incident portion 2g is adjacent to the reflecting surface 2c and faces the exit surface 2b, and a side surface 2h connecting the incident portion 2g and the exit surface 2b. The light guide 2 has a plurality of incident prism portions 23, each of which is a triangular prism-shaped protrusion, arranged in a repeated manner. One surface 23a of each incident prism portion 23, which is substantially parallel to the exit portion 21a, corresponds to the incident surface 2a. In other words, the light guide 2 is configured such that the plurality of parallel surfaces 23a face the exit surface 2b in the second direction D2 and function as the incident surface 2a. The plurality of incident prism portions 23 extend along the third direction D3 and are arranged in a repeated manner along the first direction D1. The multiple entrance prism portions 23 protrude from the reflecting surface 2c, and the surface facing the reflecting surface 2c is one surface 23a that functions as the entrance surface, and the surface adjacent to the one surface 23a is the other surface 23b. The other surface 23b is, for example, a flat surface inclined at an angle that does not interfere with the incident light L2 entering from the adjacent one surface 23a, and may be covered with a light-shielding film (not shown) to prevent external light L1 from entering the interior. The side surface 2h is located in the opposite direction from the terminal surface 2d in the first direction D1, and is a non-optical surface that is not used to reflect the incident light L2.
[0057] In this embodiment, the light guide holder 3 has a side cover 35 instead of the rod-shaped body 32, and is composed of a holder part 31 and the side cover 35. In the light guide holder 3, for example, the gap between the holder part 31 and the side cover 35 forms a first opening 33 and a second opening 34, and the first opening 33 is provided so as to be approximately parallel to the second opening 34. In this embodiment, the first opening 33 exposes the incident part 2g from the light guide holder 3. The side cover 35 is, for example, in the shape of a plate that follows the side surface 2h of the light guide 2.
[0058] The first transparent cover 4 is, for example, in the shape of a shallow box having a frame portion 41 fixed to the light guide holder 3 and a flat ceiling portion 42 closing one end of the frame portion 41, and is shaped so as not to abut against the entrance prism portion 23 of the entrance portion 2g. The first transparent cover 4 is attached to the light guide holder 3, for example, so that the ceiling portion 42 is approximately parallel to the plane formed by the reflecting surface 2c, and the ceiling portion 42 is inclined by 3° or more with respect to the plane formed by the one surface 23a.
[0059] The present embodiment also provides an optical element 1 that can achieve the same effects as the first embodiment. As described above, the shape of the light guide 2 having a half-mirrorless structure may be changed, and the shapes and configurations of the light guide holder 3 and transparent covers 4 and 5 that hold it may also be changed appropriately depending on the shape of the light guide 2. Note that, in the present embodiment, the optical element 1 corresponding to a modification of the first embodiment has been described as a representative example, but is not limited to this example and may be combined with the second or third embodiment.
[0060] (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.
[0061] 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. [Explanation of symbols]
[0062] 2...light guide, 2a...incident surface, 2b...exit surface, 2c...reflecting surface, 21...exit prism portion, 21a...exit portion, 22...flat portion, 23a...one surface of (incident prism portion), 3...light guide holder, 321...louver, 33...first opening, 34...second opening, 4...first transparent cover, 5...second transparent cover, 5a...outer surface, 51...reflection suppression portion, C1...exit center, C2...iris center, D1...light guide direction (first direction), D4...reference normal direction, ELP...iris, L1...external light, L2...incident light, Lr...louver length, P1...reference surface, PL...left end of iris
Claims
1. a light guide (2) made of a translucent material, the light guide (2) having an incident surface (2a, 23a) that allows external scene light (L1) to enter the interior, an exit surface (2b) that is made up of a plurality of protruding exit prism portions (21) that emit a portion of the incident light (L2) that has entered from the incident surface to the outside and a plurality of flat portions (22) that reflect a portion of the incident light by total reflection, and a reflection surface (2c) that reflects the light reflected by the flat portions toward the exit surface; a light guide holder (3) for holding the light guide, the light guide holder having a first opening (33) for exposing the incident surface of the light guide and a second opening (34) for exposing the exit surface of the light guide; a first transparent cover (4) made of a light-transmitting material, attached to the first opening, and covering the incident surface; and a second transparent cover (5) made of a light-transmitting material, attached to the second opening, and covering the exit surface.
2. the first transparent cover is held by the light guide holder in a state inclined at an angle of 3° or more with respect to the incident surface, The optical member according to claim 1 , wherein the second transparent cover is held by the light guide holder in a state inclined at an angle of 3° or more with respect to a plane defined by the flat portion.
3. The optical member according to claim 1 , wherein the first transparent cover and the second transparent cover have a transmittance of 60% or more for light in the visible light region with wavelengths of 450 nm to 750 nm and a thickness of 0.25 mm or more.
4. The optical element of claim 1, wherein the second transparent cover has an outer surface (5a) opposite the exit surface, and a reflection suppression portion (51) on the outer surface that suppresses reflection of light incident on the outer surface from the outside.
5. The optical element according to claim 1 , wherein the light guide holder has a louver (321) that prevents external light from entering a predetermined area of the second transparent cover, including an end portion on the side of the incident surface.
6. The exit prism portion has an exit portion (21a) that exits the incident light to the outside, The direction along the direction in which the plurality of exit prism portions and the flat portion are arranged is defined as the light guide direction (D1), the plane formed by the plurality of flat portions is defined as the reference plane (P1), the normal direction to the reference plane is defined as the reference normal direction (D4), the louver inclination angle which is the angle between the direction along the extension direction of the louver and the reference normal direction is defined as θr1, the center of the exit portion of the exit prism portion which is located at the center in the light guide direction among the plurality of exit prism portions is defined as the exit center (C1), and the angle between the reference normal direction and a virtual straight line (VL3) obtained by connecting the exit center and the center (C2) of the iris (ELP) of the vehicle to which the optical element is attached is defined as θw, 6. The optical member according to claim 5, wherein the louver satisfies θr1-15°≦θw≦θr1+15°.
7. The surface of the second transparent cover opposite to the light-emitting surface is defined as an outer surface (5a), and the length of the louver from the outer surface to the tip end is defined as a louver length (Lr), The optical element of claim 5, wherein the louver length is greater than or equal to the length at which virtual light obtained by connecting the left end (PL) of the iris (ELP) of the vehicle to which the optical element is attached and the terminal end (5aa) of the second transparent cover opposite the incident surface intersects with a virtual light ray when specularly reflected by the outer surface.
8. The optical element according to claim 5 , wherein the louver has a transmittance of 1% or less for light in the visible light region with wavelengths of 450 nm to 750 nm.
Citation Information
Patent Citations
Optical member
JP2023028532A