Optical components

Abstract

It is attached to a member inclined with respect to the vertical direction, suppressing the occurrence of invisible areas in optical members made of translucent materials, and reducing visibility due to parallax between emitted light and actual ambient light. [Solution] The optical member comprises an incident section 2a consisting of a plurality of incident prism sections having an incident surface, an exit surface 2b that emits incident light to the outside, and a light guide body 2 having an upper surface 2f and a lower surface 2g connecting the incident section 2a and the exit surface 2b. With the direction along the extension direction of the incident prism section as the y-direction, the upper surface 2f and the lower surface 2g are inclined at ωu and ωd, respectively, with respect to the z-direction which is perpendicular to the y-direction. With respect to the inclination reference angle ω, the upper surface 2f and the lower surface 2g satisfy ωu≦ω and ωd≧ω. The inclination reference angle ω is sin -1 (sin(θx+α) / n cosψx For ωo calculated using ), the following conditions must be met: ωo-10°≦ω≦ωo+10°. ψx is the inclination angle of the incident plane, α is the incident angle of the ambient light L1, and θx is the inclination angle of the light guide 2 with respect to the vertical.

Description

Technical Field

[0001] The present disclosure relates to an optical member composed of a light-transmitting material.

Background Art

[0002] Conventionally, examples of this type of optical member include those described in Patent Document 1. The optical member described in Patent Document 1 has an incident surface for allowing external light to enter the interior, an exit surface composed of a plurality of triangular prism portions and flat portions facing the incident surface, and a reflection surface for reflecting internally reflected light at the exit surface to the exit surface side, and includes a light guide formed of a light-transmitting material. This optical member is used as a blind spot assisting device that allows a user to visually recognize the scene in a blind spot region by emitting a part of the incident light from the incident surface from one surface of the prism portion to the user side and reflecting the other part of the incident light by the flat portion and the reflection surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the above optical member is attached to a member inclined with respect to the vertical direction, such as the A pillar of an automobile, for example, the light incident on the incident surface refracts when entering the interior, resulting in a region where the incident light does not reach a part of the exit surface. In this case, the region of the exit surface where the incident light does not reach is recognized by the user as an invisible region where the scene cannot be visually recognized. Also, in this case, due to the refraction, the incident light travels downward inside the light guide, causing a parallax between the emitted light emitted from the exit surface and the actual scene light that directly reaches the user's eyes without passing through the optical member among the light reaching the user's eyes. When the parallax exceeds a predetermined value, the visibility deteriorates.

[0005] In view of the above, this disclosure aims to provide an optical component made of a translucent material that, when attached to a member inclined with respect to the vertical, reduces the invisible area and suppresses the decrease in visibility due to parallax between emitted light and actual ambient light. [Means for solving the problem]

[0006] According to one aspect of this disclosure, an optical member is attached to a mounting member (10) that is inclined with respect to the vertical direction, and guides ambient light from an area including a blind spot created by the mounting member, The incident section (2a) is composed of a plurality of incident prism sections (21) having an incident surface (21a) into which ambient light enters the interior, An emission surface (2b) having multiple emission prism sections (3) each having an emission section (3a) that emits a portion of the incident light from the incidence surface to the outside, Reflectors (4, 5) that reflect the other portion of the incident light and A reflective surface (2c) that reflects the reflected light from the reflective section towards the emitting surface, The terminal surface (2e) of the reflective surface connects the end opposite to the incident surface to the exit surface, The upper surface (2f) connecting the incident surface and the exit surface, The device comprises a light guide (2) made of a translucent material with refractive index n, which has a lower surface (2g) that connects the incident surface and the exit surface and is located on the opposite side from the upper surface, The vertical direction is defined as the Y-axis, the left-right direction perpendicular to the Y-axis and connecting the light guide and the mounting member is defined as the X-axis, the front-back direction perpendicular to the X-axis and Y-axis is defined as the Z-axis, the plane formed by the X-axis and Y-axis is defined as the XY plane, the plane formed by the Y-axis and Z-axis is defined as the YZ plane, and the plane formed by the X-axis and Z-axis is defined as the XZ plane, the edge formed by the end of the incident portion opposite to the reflective surface is defined as the incident end (2aa), and the edge formed by the end of the exit surface on the end surface side is defined as the end edge (2b1), The light guide is positioned with its incident end tilted at an angle of θx in the YZ plane and at an angle of θz in the XY plane, with respect to the Y axis. Let the line connecting a point (C) at the terminal edge and the user's viewpoint (EP) be a virtual line (VL1), let φx be the angle between the virtual line and the Z-axis direction in the YZ plane, let φy be the angle between the virtual line and the Z-axis direction in the XZ plane, let the z-direction be the direction in which the multiple emission prism sections are arranged and which is perpendicular to the extension direction of the emission prism sections, let α be the apparent angle of incidence between the ambient light incident on the incident section and the z-direction, let ψx be the angle between the incident surface and the normal direction to the reflecting surface, and let sinφx / sinφy=tanδ,

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[0007] This optical element suppresses the occurrence of invisible regions by setting the tilt reference angle ω to satisfy ωo-10°≦ω≦ωo+10° for the angle ωo calculated by equations (5) and (6), such that the upper surface satisfies ωu≦ω and the lower surface satisfies ωd≧ω. Furthermore, this optical element ensures that the parallax is below a predetermined level by satisfying equation (4) when Wd, which is the distance traveled by the maximum round-trip light from the incident end to the exit end in a direction perpendicular to the incident end, is equal to or below a predetermined level, thereby suppressing the reduction in visibility caused by parallax.

[0008] Note that the reference numerals in brackets attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0009] [Figure 1] It is a figure which shows the optical member of 1st Embodiment, and its attachment example. [Figure 2] It is a perspective view of the light guide in 1st Embodiment. [Figure 3] It is a sectional view taken along line III-III of FIG. 2. [Figure 4] It is an explanatory view about the apparent incident angle of the external scene light incident on the light guide, the angle of the incident light, the inclination angle of the upper surface, and the inclination angle of the lower surface. [Figure 5] It is an explanatory view about the light guiding and the sectional light guiding distance in the light guide. [Figure 6] It is an explanatory view about the deviation amount between the emitted light from the light guide and the actual scene light. [Figure 7] It is an explanatory view about the inclination angle of the incident part in the XY plane. [Figure 8] It is an explanatory view about the inclination angle of the incident part in the YZ plane, and the angle of the emitted light reaching the viewpoint position. [Figure 9] It is an explanatory view about the invisible region generated in the light guide of the first comparative example in a rectangular plate shape. [Figure 10] It is a figure which shows a state seen from the viewpoint position of the user of the state of FIG. 9. [Figure 11] It is an explanatory view about the invisible region in the case where the light guide of the first comparative example of FIG. 9 is inclined and arranged. [Figure 12] It is a figure which shows a state seen from the viewpoint position of the user of the state of FIG. 11. [Figure 13] It is an explanatory view about the invisible region generated in the light guide of the second comparative example in a parallelogram plate shape. [Figure 14] It is an explanatory view about the angle in the XZ plane of the emitted light reaching the viewpoint position. [Figure 15] This diagram illustrates the apparent incident angle of ambient light, the angle of incident light, the inclination angle of the upper surface, and the inclination angle of the lower surface of the light guide according to the second embodiment. [Figure 16] This diagram illustrates the inclination angle of the incident portion in the YZ plane and the angle of the emitted light reaching the viewpoint position. [Figure 17] This is an explanatory diagram regarding the angle of the emitted light reaching the viewpoint position in the XZ plane. [Figure 18] This figure corresponds to Figure 5 and is an explanatory diagram of the light guide and cross-sectional light guide distance according to the third embodiment. [Figure 19] This figure corresponds to Figure 5 and is an explanatory diagram of the light guide and cross-sectional light guide distance according to the fourth embodiment. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0011] (First Embodiment) The optical member 1 of the first embodiment will now be described. The optical member 1 of this embodiment is used as a blind spot assisting device that is attached to, for example, a member or obstacle that obstructs the user's field of view and creates a blind spot, and allows the user to see the scenery in the blind spot area. As shown in Figure 1, for example, the optical member 1 is attached to a mounting member 10 of a light-shielding body which has a portion inclined with respect to the vertical direction, and guides ambient light from the area that becomes a blind spot due to the light-shielding body toward the user, allowing the user to see the scenery in the blind spot area. In the case of in-vehicle applications, the mounting member 10 is, for example, the A-pillar of the vehicle on which it is mounted, but is not limited thereto.

[0012] In this specification, the optical element 1 is described as a vehicle-mounted blind spot assist device, and the mounting member 10 is the A-pillar of the vehicle, as a representative example. For the sake of explanation, as shown in Figure 1, the direction along the vertical direction is referred to as the "Y-axis direction," the direction perpendicular to the Y-axis direction and connecting the light guide 2 (described later) and the mounting member 10 is referred to as the "X-axis direction," and the direction perpendicular to both the X-axis and Y-axis directions is referred to as the "Z-axis direction." In this case, the X-axis direction corresponds to the width direction of the vehicle body, i.e., the left-right direction, the Y-axis direction corresponds to the up-down direction of the vehicle body, and the Z-axis direction corresponds to the overall length direction of the vehicle body, i.e., the front-rear direction. Furthermore, the plane to which the X-axis and Y-axis directions belong is referred to as the "XY plane," the plane to which the X-axis and Z-axis directions belong is referred to as the "XZ plane," and the plane to which the Y-axis and Z-axis directions belong is referred to as the "YZ plane."

[0013] [Basic configuration] The optical member 1 of this embodiment includes, for example, a light guide 2 as shown in Figure 2, and a holding member (not shown) that holds the light guide 2 on the mounting member 10. The optical member 1 is used with the emitting surface 2b of the light guide 2, which will be described later, facing the user's viewpoint. The holding member (not shown) is, for example, separate from the light guide 2 and the mounting member 10, but may also be formed directly on the mounting member 10. The optical member 1 guides light from a blind spot area inside the light guide 2 and emits it towards the user, thereby allowing the user to see the scene in the blind spot area. The optical member 1 is mounted at an angle with respect to the vertical to match the inclination of the mounting member 10, and the angles of the upper surface 2f and lower surface 2g of the light guide 2, which will be described later, are adjusted so that the invisible area and parallax can be reduced. In Figure 2, to make it easier to understand the surface of the light guide 2 that is not directly visible from the angle shown, a part of the outer casing of the light guide 2 that is not visible is shown with a dashed line.

[0014] The light guide 2 is a member having, for example, an incident portion 2a, a reflective surface 2c adjacent to the incident portion 2a, an exit surface 2b facing the incident portion 2a and the reflective surface 2c, a side surface 2d connecting the incident portion 2a and the exit surface 2b, and an end surface 2e connecting the exit surface 2b and the reflective surface 2c. The light guide 2 has an upper surface 2f and a lower surface 2g that connect the incident portion 2a, the exit surface 2b, the reflective surface 2c, the side surface 2d, and the end surface 2e, and which face each other. The light guide 2 is, for example, a single transparent member made of a light-transmitting material. As the light-transmitting material, for example, resin materials such as polyethylene terephthalate, polycarbonate, polyethylene, and acrylic, or inorganic materials such as glass can be used. In this embodiment, the light guide 2 is a mirrorless structure without a mirror, made of a reflective material different from the light-transmitting material, and is designed to guide light by totally reflecting the incident light from the incident part 2a inside.

[0015] For the sake of explanation, as shown in Figure 5, the light directed from the incident section 2a towards the light guide 2 will be referred to as "external light L1," and the light from the incident section 2a that enters the interior of the external light L1 will be referred to as "incident light L2." Furthermore, the light from the incident light L2 that is emitted to the outside from the output prism section 3, which will be described later, will be referred to as "exit light L3."

[0016] The incident section 2a is formed by a plurality of incident prism sections 21, which are triangular projections in cross-sectional view, arranged repeatedly and continuously with their extension directions aligned. As shown in Figure 3, for example, one side of the outer surface of the plurality of incident prism sections 21, opposite to the reflective surface 2c adjacent to the incident section 2a, is the incident surface 21a that allows a portion of the ambient light L1 to enter the interior. The plurality of incident prism sections 21 are arranged such that the heights of the portions protruding from the reflective surface 2c are approximately the same, and their respective incident surfaces 21a are approximately parallel. Approximately the same includes not only cases where they are completely identical, but also cases where they are not completely identical due to unavoidable errors such as manufacturing errors, but are nearly identical. The side of the outer surface of the plurality of incident prism sections 21 facing the reflective surface 2c is the adjacent surface 21b. The inclination angle of the adjacent surface 21b is below a predetermined value so as not to obstruct the incidence of ambient light L1 onto the incident surface 21a of the other adjacent incident prism sections 21. The incident end 2aa is defined as the side of the incident portion 2a that is opposite to the reflective surface 2c, and the incident end 2aa is, for example, substantially parallel to the extending direction of the incident prism portion 21. "Substantially parallel" includes not only cases where they are perfectly parallel, but also cases where there are errors due to unavoidable factors such as manufacturing errors, but they can still be considered nearly parallel.

[0017] The emission surface 2b has, for example, a plurality of emission prism portions 3 which are triangular protrusions in cross-sectional view, and a plurality of flat portions 4 adjacent to them which are planes substantially parallel to the reflection surface 2c. The emission surface 2b is the surface to which the incident light L2 from the incident portion 2a first reaches. The emission surface 2b is composed of a first region 2ba in which the plurality of emission prism portions 3 and flat portions 4 are arranged alternately and repeatedly, and a second region 2bb in which only the plurality of emission prism portions 3 are arranged repeatedly, as shown in Figure 3 for example. The first region 2ba is located on the side of the incident portion 2a and faces the incident portion 2a. The first region 2ba is the region in which the incident light L2 is emitted to the outside and internally reflected. The second region 2bb is located on the side of the end surface 2e and faces the reflection surface 2c. The second region 2bb is the region in which the incident light L2 is not internally reflected and a portion of the incident light L2 is emitted to the outside as emitted light L3.

[0018] Each of the multiple emission prism sections 3 has an emission section 3a, which is the surface that emits the incident light L2 to the outside, and an adjacent other surface 3b, and is arranged in parallel, for example, with its extension direction aligned. The emission section 3a is, for example, substantially parallel to the incident surface 21a. The extension direction of the emission prism section 3 is aligned with that of the incident prism section 21.

[0019] The multiple flat sections 4 are, for example, flat surfaces located on the same plane, and are first reflective surfaces that reflect the incident light L2 toward the reflective surface 2c by total internal reflection. In other words, the flat sections 4 can also be called reflective sections, and are, for example, approximately parallel to the reflective surface 2c. Here, the angle between the direction normal to the plane formed by the flat sections 4 or the reflective surface 2c (hereinafter simply referred to as the "normal direction") and the direction of propagation of the incident light L2 is defined as the angle of incidence φ, and the refractive index of the constituent material is n (n>1). In this case, the light guide 2, with the external medium being air (refractive index = 1), satisfies the total internal reflection condition of the following equation (1), thereby enabling light guidance in a mirrorless structure.

[0020] (Mathematics 1) sinφ≧1 / n···(1) For the sake of explanation, the direction along the normal direction will be referred to as the "x direction," the direction along the extension direction of the incident prism section 21 or the exit prism section 3 will be referred to as the "y direction," and the direction perpendicular to the y direction along the plane formed by the flat section 4 will be referred to as the "z direction." When the three axes of the X, Y, and Z directions, which are independent of the orientation of the light guide 2, are considered global directions, the x, y, and z directions can be said to be local directions that change depending on the orientation of the light guide 2. The x direction corresponds to the thickness direction of the light guide 2, and the z direction is one of the directions in which the incident light L2 is guided.

[0021] The reflective surface 2c is a second reflective surface that reflects the reflected light from the flat portion 4 of the incident light L2 towards the exit surface 2b by total internal reflection. The reflective surface 2c is the back surface when the exit surface 2b facing the user is considered the front surface. The reflective surface 2c faces the mounting member 10 with a predetermined gap between them.

[0022] The side surface 2d has a surface inclination greater than or equal to the incident angle φ, such that the incident light L2 is not emitted outward from the side surface 2d. The side surface 2d is, for example, a flat surface, but it is sufficient that it does not obstruct the incident light L2 toward the exit surface 2b, and the surface shape can be changed as appropriate.

[0023] The terminal surface 2e is the surface to which a portion of the incident light L2 ultimately reaches. The terminal surface 2e is, for example, a flat surface connecting the emission portion 3a of the emission prism portion 3, which is located furthest from the side surface 2d, and the reflective surface 2c. However, it may have other surface shapes, or it may form a single plane together with the emission portion 3a, or it may have any shape.

[0024] The upper surface 2f and the lower surface 2g, like the side surface 2d, 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 2f and the lower surface 2g are, for example, a single flat surface connecting the incident section 2a, the exit surface 2b, the reflective surface 2c, the side surface 2d, and the end surface 2e, respectively. The upper surface 2f and the lower surface 2g are either parallel or inclined relative to each other such that the distance between them in the y-direction narrows from the side surface 2d towards the end surface 2e. The upper surface 2f is configured such that, as shown in Figure 4, for example, when viewed from the exit surface 2b side, the actual angle between the edge of the upper surface 2f and the z-direction is the first inclination angle ωu, and the inclination reference angle, described later, is ω, satisfying ωu≦ω. Note that in Figure 4, for ease of viewing, some components of the light guide 2, such as the exit prism section 3, are omitted, and only a part of the outer casing is shown. The lower surface 2g is configured such that, when viewed from the emission surface 2b side, the actual angle between the edge of the lower surface 2g and the z-direction is defined as the second inclination angle ωd, and ωd ≥ ω. As a result, the invisible region on the emission surface 2b of the optical element 1 is reduced. Details of the invisible region and ω, ωu, and ωd will be described later.

[0025] As shown in Figure 5, for example, the light guide 2 satisfies the following equation (2), with the cross-sectional light guide distance being Wd. The cross-sectional light guide distance Wd is the distance traveled in the direction along the plane formed by the reflective surface 2c or the flat surface 4, i.e., the light guide direction, in a cross section perpendicular to the incident end 2aa, from the incident part 2a to the exit part 3a. The maximum round-trip light is the incident light L2 emitted to the outside that has the maximum number of round trips between the flat surface 4 and the reflective surface 2c. For example, if the exit surface 2b is composed of two regions 2ba and 2bb, the maximum round-trip light is the incident light L2 that makes one and a half round trips within the light guide 2, with the first portion of the incident light L2 from the incident part 2a reaching the flat surface 4 being considered half a round trip.

[0026]

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[0027] Furthermore, in equation (2), θz is the angle (in degrees) between the Y-axis direction and the incident end 2aa of the light guide 2 in the XY plane, as shown in Figure 7, for example; that is, the inclination angle of the incident end 2aa in the XY plane. In equation (2), θx is the angle (in degrees) between the incident end 2aa of the light guide 2 and the Y-axis direction in the YZ plane, as shown in Figure 8, for example; that is, the inclination angle of the incident end 2aa in the YZ plane. In equation (2), φx is the angle (in degrees) between the virtual line VL1 connecting the user's viewpoint position EP, located behind the light guide 2 in the Z-axis direction, and a point C on the terminal edge 2b1, and the Z-axis direction in the YZ plane. In other words, φx corresponds to the angle of incidence of the emitted light L3 to the viewpoint position EP in the YZ plane, assuming that the emitted light L3, which is emitted from point C of the incident light L2 incident light L2 incident from the incident part 2a, reaches the viewpoint position EP. The virtual straight line VL1 can also be described as the direction along the emitted light L3, which is emitted from point C and reaches the viewpoint position EP. "Rearward" in the Z-axis direction refers to the direction behind the light guide 2, with the direction from the incident end 2aa to the terminal edge 2b1 along the Z-axis direction being defined as the rearward direction. Here, "rearward direction" means the direction pointed to by the arrow indicating the Z-axis direction as shown in Figure 8, etc., i.e., the positive side of the Z-axis. The terminal edge 2b1 is the edge located at the boundary between the emitted surface 2b and the terminal surface 2e. Point C is, for example, the center of the terminal edge 2b1. The viewpoint position EP is, for example, any point (usually the center point) within the region known as the eye range, or eye lips, which statistically represents the distribution of the driver's eye position when the optical element 1 is mounted on a vehicle. The eye lips is defined, for example, in the Japanese Industrial Standard JIS D0021:1998.

[0028] Here, if a driver of a car is looking 40m ahead, the driver's depth of field ranges from approximately 3m to infinity. The apparent angular difference between the light emitted L3 from the light guide 2 reaching the driver's viewpoint and the actual ambient light, i.e., parallax (unit:°), is denoted as ψ, and the distance to the actual scene seen by the driver, i.e., the viewing distance, is denoted as D (unit:m). In this case, the parallax ψ is expressed by the following formula (3).

[0029] (Math 3) ψ = tan-1 (Lp / D)···(3) When the parallax ψ exceeds 1°, the image formed by the emitted light L3 and the actual light source in the human eye becomes distorted, causing a sense of unease in the perception of the scene. Furthermore, the unease caused by parallax ψ is greater as the viewing distance D decreases. In the driver example above, the unease caused by parallax ψ is greatest when the viewing distance D = 3m. Therefore, to reduce the unease caused by parallax ψ, the parallax ψ at a viewing distance D = 3m should be kept below 1°. According to equation (3), ψ = tan -1 (Lp / 3000)≦1 is satisfied when Lp≦52, so the displacement Lp should be 52 mm or less. For this reason, in the case of automotive applications, the optical component 1 is preferably designed to satisfy Lp≦52 in equation (2), that is, to satisfy the following equation (4), from the viewpoint of parallax suppression.

[0030]

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[0031] [Invisible areas and their reduction] Next, we will explain the invisible region that occurs in a light guide made of a translucent material with refractive index n (n>1). First, we will describe the occurrence of the invisible region in the light guide 100 of the first comparative example shown in Figure 9. In Figure 9, to make the structure of the light guide 100 easier to understand, the approximate range of the incident portion 100a, which will be described later and is located on the opposite side at the back of the paper, is shown by a dashed line.

[0032] The light guide 100 has an incident section 100a composed of a plurality of incident prism sections (not shown), an exit surface 100b composed of a plurality of exit prism sections and a flat section (not shown), and a reflective surface, side surfaces, and end surfaces (not shown). These configurations are the same as those of the light guide 2. The light guide 100 is similar to the light guide 2 in that it has an upper surface 100c and a lower surface 100d, as shown in Figure 9, for example. The light guide 100 differs from the light guide 2 in that the upper surface 100c and the lower surface 100d are flat surfaces perpendicular to and parallel to the extending direction of the incident prism sections (not shown), i.e., the prism extending direction.

[0033] Assume that the light guide 100 is attached to the mounting member 10 so that the prism extension direction coincides with the Y-axis direction. In this case, when ambient light L1 travels through the light guide 100 towards the user's viewpoint position EP, ambient light L1 enters only from a portion of the incident portion 100a, and does not enter the other portions of the incident portion 100a. As a result, an area is created on the exit surface 100b of the light guide 100 where incident light L2 does not reach, i.e., an area where exit light L3 is not emitted to the outside. This area is perceived by the user as an invisible area R where the scenery cannot be seen, as shown in Figures 9 and 10, for example. Figure 10 and Figure 12, which will be described later, show the view of the light guide 100 and the mounting member 10 from the viewpoint position EP on the driver's side when the mounting member 10 is an A-pillar.

[0034] In the mounting configuration shown in Figure 9, the prism extension direction of the light guide 100 is aligned with the Y-axis direction, so refraction that deviates from the Z-axis direction does not occur, or if it does, it is small. Also, in Figures 9 and 10, hatching is applied to the invisible region R, although this does not show a cross-section, in order to make the invisible region R easier to understand. The same applies to Figures 11 to 13, which will be discussed later.

[0035] Furthermore, an invisible region R is also generated when the light guide 100 is positioned with the prism extension direction inclined with respect to the Y-axis direction along the inclined portion of the mounting member 10, for example, as shown in Figure 11. In this case, the entire area of ​​the incident portion 100a of the light guide 100 extends beyond the mounting member 10, so ambient light L1 is incident on the entire area. At this time, in the YZ plane, the prism extension direction is inclined with respect to the Y-axis direction, and since the light guide 100 is made of a translucent material with refractive index n, the incident light L2 is refracted so as to deviate from the Z-axis direction. However, because the upper surface 100c and the lower surface 100d are inclined with respect to the Z-axis direction, a portion of the output surface 100b on the lower surface 100d side becomes a region that the incident light L2 does not reach due to the above refraction. Therefore, the emission surface 100b is perceived by the user as an invisible region R in which a portion of the area on the lower surface 100d side does not emit the emitted light L3, as shown in Figure 11 and Figure 12, which is a view of Figure 11 from a different angle. Thus, when viewed from the emission surface 100b, the rectangular light guide 100 has an invisible region R when it is attached to the mounting member 10.

[0036] Next, we will discuss the occurrence of an invisible region in the light guide 110 of the second comparative example shown in Figure 13.

[0037] The light guide 110 has an incident section 110a, an exit surface 110b, a reflective surface (not shown), side and end surfaces, an upper surface 110c, and a lower surface 110d, and is basically the same configuration as the light guide 100, which is made of a translucent material. The light guide 110 differs from the light guide 100 in that, when viewed from the exit surface 110b side, it is a parallelogram, and the direction of extension of the multiple incident prism sections (not shown) that constitute the incident section 110a is not perpendicular to the direction of the upper surface 110c and the lower surface 110d.

[0038] Even when the light guide 110 is positioned such that the prism extension direction of the incident portion 110a is tilted with respect to the Y-axis direction along the inclined portion of the mounting member 10, as shown in Figure 13, an invisible region R is still generated. In this case, the entire incident portion 100a of the light guide 110 extends beyond the mounting member 10, and ambient light L1 is incident on this entire area, while the upper surface 110c and lower surface 110d are aligned with the Z-axis direction. However, in this case, a portion of the exit surface 110b of the light guide 110 on the upper surface 110c side becomes a region where incident light L2 does not reach due to refraction. Therefore, the light guide 110 is perceived by the user as an invisible region R where a portion of the exit surface 110b on the upper surface 110c side does not emit emitted light L3.

[0039] As described above, when the comparative example light guides 100 and 110 are attached to a mounting member 10 having an inclined portion that is inclined with respect to the vertical direction, ambient light L1 does not enter a part of the incident portion, or an invisible region R is created due to refraction at the time of incidence.

[0040] In contrast, the light guide 2 according to this embodiment is configured such that, in order to reduce the invisible region R, the first inclination angle ωu of the upper surface 2f and the second inclination angle ωd of the lower surface 2g satisfy ωu≦ω and ωd≧ω with respect to the inclination reference angle ω, respectively. The inclination reference angle ω is the reference angle for the inclination angles of the upper surface 2f and the lower surface 2g, satisfying ωo-10°≦ω≦ωo+10° with respect to the ideal angle ωo (unit:°) calculated by the following formulas (5) and (6).

[0041]

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[0042]

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[0043] (Math 7) tanδ = sinφx / sinφy ···(7) The angle ωo corresponds to the tilt angle with respect to the z direction of incident light L2, which is refracted after ambient light L1, incident on the incident part 2a at an incident angle α, enters the inside of the light guide 2 with refractive index n. Here, the light guide 2 is attached to the mounting member 10 such that the upper surface 2f is on the upper side in the Y-axis direction and the lower surface 2g is on the lower side in the Y-axis direction. In this case, by adjusting the first tilt angle ωu so that the upper surface 2f is ωu ≤ ωo, the incident light L2 reaches the entire region on the upper surface 2f side of the emission surface 2b, and the generation of the invisible region R is suppressed. Also, by adjusting the second tilt angle ωd so that the lower surface 2g is ωd ≥ ωo, the incident light L2 reaches the entire region on the lower surface 2g side of the emission surface 2b, and the generation of the invisible region R is suppressed. Furthermore, by configuring the light guide 2 to satisfy ωu≦ω and ωd≧ω with respect to a tilt reference angle ω within ±10° of angle ωo, the occurrence of the invisible region R is minimized. This tolerance of ±10° takes into account the effects of processing errors in the light guide 2 and angular errors in mounting to the mounting member 10.

[0044] According to this embodiment, the upper surface 2f of the light guide 2 satisfies ωu≦ω, and the lower surface 2g satisfies ωd≧ω, resulting in an optical element 1 in which the generation of the invisible region R is suppressed. Furthermore, the optical element 1 satisfies equation (4) in terms of the cross-sectional light guide distance Wd, so that the parallax ψ at the viewing distance D=3m is 1° or less, thereby suppressing the reduction in visibility caused by parallax. The optical element 1 also has the following features.

[0045] (1) Point C, which is one end of the virtual straight line VL1, is the center of the terminal edge 2b1. As a result, the ideal angle ωo is at the center of the upper surface 2f and the lower surface 2g of the light guide 2, and the optical member 1 is such that the generation of the invisible region R on either the upper surface 2f side or the lower surface 2g side of the emission surface 2b is efficiently suppressed.

[0046] (Second Embodiment) The optical member 1 of the second embodiment will now be described. The optical member 1 of this embodiment differs from the first embodiment in that the design of the inclination angles ωu and ωd of the upper surface 2f and lower surface 2g has been changed. This embodiment will mainly describe this difference.

[0047] In this embodiment, the upper surface 2f is calculated by taking αa as the apparent incident angle of the ambient light L1 on the upper surface 2f side of the incident section 2a, as shown in Figure 15, for example. αa corresponds to the apparent incident angle between the ambient light L1, which becomes the emitted light L3 that eventually reaches the user's viewpoint position EP after passing through the first endpoint A (described later), and the z-direction. In this embodiment, the lower surface 2g is calculated by taking αb as the apparent incident angle of the ambient light L1 on the lower surface 2g side of the incident section 2a, for example. αb corresponds to the apparent incident angle between the ambient light L1, which becomes the emitted light L3 that eventually reaches the user's viewpoint position EP after passing through the second endpoint B (described later), and the z-direction. These incident angles αa and αb, as well as the upper and lower limits ωa and ωb, are calculated using the following formulas (8) to (11), respectively.

[0048]

number

[0049]

number

[0050]

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[0051]

number

[0052] (Math. 12) tanδa=sinφxa / sinφya (12) In equation (9), φxb is the angle (in degrees) in the YZ plane between the virtual line VL3, which connects the user's viewpoint position EP and the second endpoint B on the lower surface 2g side of the terminal edge 2b1, and the Z-axis direction, as shown in Figure 16, for example. In equation (9), φyb is the angle (in degrees) in the XZ plane between the virtual line VL3 and the Z-axis direction, as shown in Figure 17, for example. In equation (9), δb is the angle determined by the degree of inclination of the light guide 2 attached to the mounting member 10 in the YZ and XZ planes, and is calculated by the following equation (13). In this embodiment, if the virtual line VL2 is the first virtual line, then the virtual line VL3 is the second virtual line.

[0053] (Math 13) tanδb = sinφxb / sinφyb ···(13) When the first inclination angle ωu of the upper surface 2f of the light guide 2 is less than or equal to the upper limit value ωa, incident light L2 reaches the entire upper surface 2f side of the emission surface 2b, suppressing the generation of invisible region R. When the second inclination angle ωd of the lower surface 2g of the light guide 2 is greater than or equal to the lower limit value ωb, incident light L2 reaches the entire lower surface 2g side of the emission surface 2b, suppressing the generation of invisible region R. In this embodiment, the upper limit value ωa of the first inclination angle ωu of the upper surface 2f and the lower limit value ωb of the second inclination angle ωd of the lower surface 2g of the light guide 2 are designed individually, so that the generation of invisible region R is suppressed efficiently without waste.

[0054] Furthermore, considering the effects of processing errors in the light guide 2 and angular errors in mounting to the member 10, setting an allowable range of 10° for the upper limit ωa and the lower limit ωb minimizes the occurrence of the invisible region R. In other words, the light guide 2 minimizes the occurrence of the invisible region R by ensuring that the upper surface 2f satisfies ωa-10°≦ωu≦ωa and the lower surface 2g satisfies ωb≦ωd≦ωb+10°.

[0055] This embodiment also provides an optical element 1 that has the same effects as the first embodiment described above. Furthermore, since the center values ​​of the inclination angles ωu and ωd are individually designed for the upper surface 2f and lower surface 2g of the light guide 2, this optical element 1 has the effect of reducing the generation of the invisible region R more efficiently and without waste.

[0056] (Third embodiment) The optical member 1 of the third embodiment will now be described. The optical member 1 of this embodiment differs from the first embodiment in that the configuration of the emission surface 2b has been changed, as shown in Figure 18, for example. This embodiment will mainly describe this difference.

[0057] In this embodiment, the emission surface 2b has a configuration in which emission prism sections 3 and flat sections 4 are alternately and repeatedly arranged throughout its entire surface. The emission surface 2b has, for example, a constant pitch between adjacent emission prism sections 3, and has only one region that performs emission and internal reflection of incident light L2. In this embodiment, the maximum number of round trips of incident light L2 is k (k: an integer of 1 or more), and the distance between the flat section 4 and the reflective surface 2c in the x direction, i.e., the thickness of the light guide 2, is T (unit: mm). In this case, the cross-sectional light guide distance Wd is calculated as the distance traveled when the light guide 2 of thickness T makes (k+1 / 2) round trips.

[0058] This embodiment also provides an optical element 1 that has the same effects as the first embodiment described above.

[0059] (Fourth Embodiment) The optical member 1 of the fourth embodiment will now be described. The optical member 1 of this embodiment differs from the first embodiment in that the configuration of the emission surface 2b is changed, as shown in Figure 19, for example, and it further has a reflective portion 5 that is independent of the emission surface 2b. This embodiment will mainly describe these differences.

[0060] In this embodiment, the emission surface 2b has only multiple emission prism sections 3 throughout its entire surface, and the emission prism sections 3 are arranged in a repeating pattern. In other words, in this embodiment, the emission surface 2b is a region that emits only incident light L2.

[0061] The reflective section 5 is positioned between the incident section 2a and the reflective surface 2c and the exit surface 2b, and is arranged parallel to them. As shown in Figure 19, for example, the reflective section 5 is composed of a half-mirror that transmits a portion of the incident light L2 from the incident section 2a or the reflective surface 2c to the exit surface 2b, and reflects the other portion of the incident light L2 back to the reflective surface 2c. The reflective section 5 is made of a metal material, for example, and is formed by a vacuum deposition method such as vapor deposition or sputtering. The reflective section 5 is a translucent material that transmits a portion of the visible light and a reflective material that reflects the other portion of the visible light.

[0062] In this embodiment, the light guide 2 is obtained by forming the upper half, which is the upper half on the reflective surface 2c side of the reflective portion 5, and the lower half, which is the lower half on the emission surface 2b side of the reflective portion 5, with transparent resin material or the like, forming the reflective portion 5 on the upper or lower portion, and then integrating them. In this embodiment as well, the cross-sectional light guide distance Wd is defined according to the maximum number of round trips of the incident light L2, similar to the third embodiment described above.

[0063] This embodiment also provides an optical element 1 that has the same effects as the first embodiment described above.

[0064] (Other embodiments) This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms including one, more, or less of those elements, fall within the scope and concept of this disclosure.

[0065] It goes without saying that, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated to be particularly essential or unless it is clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc., of the components are mentioned, the embodiment is not limited to those shapes, positional relationships, etc., unless explicitly stated or unless it is clearly limited to a specific shape, positional relationship, etc., in principle. [Explanation of Symbols]

[0066] 2...light guide, 2a...incident part, 2aa...incident end, 2b...exit surface, 2b1...end edge, 2c...reflecting surface, 2e...end surface, 2f...top surface, 2g...bottom surface, 21...incident prism part, 21a...incident surface, 3...exit prism part, 3a...exit part, 4, 5...reflecting parts, 10...mounted member, A...first endpoint (of the end edge), B...second endpoint (of the end edge), C...a point on the end edge, EP...user's viewpoint position, VL1...virtual line connecting C and EP, VL2...virtual line connecting A and EP, VL3...virtual line connecting B and EP

Claims

1. An optical member that is attached to a mounting member (10) that is inclined with respect to the vertical direction, and which guides ambient light from an area including a blind spot created by the mounting member, The incident section (2a) is composed of a plurality of incident prism sections (21) having an incident surface (21a) into which the external light enters the interior, An exit surface (2b) having a plurality of exit prism sections (3) each having an exit section (3a) that exits a portion of the incident light from the incident surface to the outside, Reflecting parts (4, 5) that reflect another portion of the incident light and A reflective surface (2c) that reflects the reflected light from the reflective portion toward the emission surface, The end surface (2e) of the reflective surface that connects the end opposite to the incident surface to the exit surface, The upper surface (2f) connecting the incident portion and the exit surface, The light guide (2) is made of a translucent material with refractive index n and has a lower surface (2g) that connects the incident portion and the exit surface and is located on the opposite side from the upper surface. The vertical direction is defined as the Y-axis direction, the left-right direction perpendicular to the Y-axis direction and connecting the light guide and the mounting member is defined as the X-axis direction, the front-back direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction, the plane formed by the X-axis direction and the Y-axis direction is defined as the XY plane, the plane formed by the Y-axis direction and the Z-axis direction is defined as the YZ plane, the plane formed by the X-axis direction and the Z-axis direction is defined as the XZ plane, the edge of the incident portion opposite to the reflective surface is defined as the incident end (2aa), and the edge of the exit surface on the side of the end surface is defined as the end edge (2b1), The light guide is positioned such that its incident end is inclined with respect to the Y-axis direction at an angle of θx in the YZ plane and at an angle of θz in the XY plane. Let the line connecting a point (C) on the terminal edge and the user's viewpoint (EP) be a virtual line (VL1), let φx be the angle between the virtual line and the Z-axis direction in the YZ plane, let φy be the angle between the virtual line and the Z-axis direction in the XZ plane, let the z-direction be the direction in which the plurality of emission prism sections are arranged and which is perpendicular to the extension direction of the emission prism sections, let α be the apparent angle of incidence between the ambient light incident on the incident section and the z-direction, let ψx be the angle between the incident surface and the normal direction to the reflecting surface, and let sinφx / sinφy = tanδ, [Math 5] [Math 6] Let ωo be the ideal angle between the upper or lower surface and the z-direction, calculated using formulas (5) and (6), and let the angle ω satisfying ωo - 10° ≤ ω ≤ ωo + 10° be the reference angle of inclination, let ωu be the actual angle between the upper surface and the z-direction, and let ωd be the actual angle between the lower surface and the z-direction. The aforementioned upper surface satisfies ωu ≤ ω, The aforementioned lower surface satisfies ωd≧ω, An optical member wherein, of the light emitted from the emission surface, the light with the largest number of round trips between the reflecting portion and the reflecting surface is defined as the maximum round trip light, and Wd is the distance the maximum round trip light travels from the incident portion to the emission portion in a direction perpendicular to the incident end within the plane formed by the reflecting surface, such that Wd satisfies formula (4). [Math 4]

2. The optical member according to claim 1, wherein the aforementioned point is the center of the terminal edge.

3. Let the endpoint of the end edge on the upper surface side be the first endpoint (A), and the endpoint of the end edge on the lower surface side be the second endpoint (B), and let the line connecting the first endpoint and the viewpoint position be the first virtual line (VL2), and let the line connecting the second endpoint and the viewpoint position be the second virtual line (VL3), and let the angle between the first virtual line and the Z-axis direction in the YZ plane be φxa, and let the angle between the first virtual line and the Z-axis direction in the XZ plane be φya, and the second virtual line and Let φxb be the angle that the Z-axis direction makes with the YZ plane, let φyb be the angle that the second virtual line and the Z-axis direction make with the XZ plane, let αa be the apparent angle of incidence between the ambient light and the z-direction at the upper end of the incident portion, let αb be the apparent angle of incidence between the ambient light and the z-direction at the lower end of the incident portion, let sinφxa / sinφya = tanδa, and let sinφxb / sinφyb = tanδb, [Number 8] [Number 9] [Number 10] [Math 11] Let ωa be the upper limit of the ideal angle between the upper surface and the z-direction, calculated using formulas (8) and (10); let ωb be the lower limit of the ideal angle between the lower surface and the z-direction, calculated using formulas (9) and (11); let ωu be the actual angle between the upper surface and the z-direction; and let ωd be the actual angle between the lower surface and the z-direction. The aforementioned upper surface satisfies ωa - 10° ≤ ωu ≤ ωa, The lower surface satisfies ωb ≤ ωd ≤ ωb + 10°, as described in claim 1.

4. The light guide has a plurality of reflective portions which are flat portions made of the light-transmitting material, The optical member according to any one of claims 1 to 3, wherein the reflective portion constitutes a plurality of the emission prism portions and the emission surface.

5. The optical member according to claim 4, wherein the emission surface has a configuration in which the emission prism portion and the flat portion are repeatedly arranged.

6. The emission surface is composed only of a plurality of emission prism sections. The optical member according to any one of claims 1 to 3, wherein the reflective portion is a half-mirror disposed between the incident portion and the reflective surface and the exit surface, and transmits a portion of the incident light to the side of the exit surface and reflects the other portion of the incident light to the reflective surface.

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